diff options
Diffstat (limited to 'Documentation')
36 files changed, 2643 insertions, 1341 deletions
diff --git a/Documentation/ABI/testing/devlink-resource-mlxsw b/Documentation/ABI/testing/devlink-resource-mlxsw new file mode 100644 index 0000000..259ed29 --- /dev/null +++ b/Documentation/ABI/testing/devlink-resource-mlxsw @@ -0,0 +1,33 @@ +What: /kvd/ +Date: 08-Jan-2018 +KernelVersion: v4.16 +Contact: mlxsw@mellanox.com +Description: The main database in the Spectrum device is a centralized + KVD database used for many of the tables used to configure + the chip including L2 FDB, L3 LPM, ECMP and more. The KVD + is divided into two sections, the first is hash-based table + and the second is a linear access table. The division + between the linear and hash-based sections is static and + require reload before the changes take effect. + +What: /kvd/linear +Date: 08-Jan-2018 +KernelVersion: v4.16 +Contact: mlxsw@mellanox.com +Description: The linear section of the KVD is managed by software as a + flat memory accessed using an index. + +What: /kvd/hash_single +Date: 08-Jan-2018 +KernelVersion: v4.16 +Contact: mlxsw@mellanox.com +Description: The hash based section of the KVD is managed by the switch + device. Used in case the key size is smaller or equal to + 64bit. + +What: /kvd/hash_double +Date: 08-Jan-2018 +KernelVersion: v4.16 +Contact: mlxsw@mellanox.com +Description: The hash based section of the KVD is managed by the switch + device. Used in case the key is larger than 64 bit. diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net index 6856da9..2f17881 100644 --- a/Documentation/ABI/testing/sysfs-class-net +++ b/Documentation/ABI/testing/sysfs-class-net @@ -259,3 +259,27 @@ Contact: netdev@vger.kernel.org Description: Symbolic link to the PHY device this network device is attached to. + +What: /sys/class/net/<iface>/carrier_changes +Date: Mar 2014 +KernelVersion: 3.15 +Contact: netdev@vger.kernel.org +Description: + 32-bit unsigned integer counting the number of times the link has + seen a change from UP to DOWN and vice versa + +What: /sys/class/net/<iface>/carrier_up_count +Date: Jan 2018 +KernelVersion: 4.16 +Contact: netdev@vger.kernel.org +Description: + 32-bit unsigned integer counting the number of times the link has + been up + +What: /sys/class/net/<iface>/carrier_down_count +Date: Jan 2018 +KernelVersion: 4.16 +Contact: netdev@vger.kernel.org +Description: + 32-bit unsigned integer counting the number of times the link has + been down diff --git a/Documentation/bpf/bpf_devel_QA.txt b/Documentation/bpf/bpf_devel_QA.txt new file mode 100644 index 0000000..cefef85 --- /dev/null +++ b/Documentation/bpf/bpf_devel_QA.txt @@ -0,0 +1,519 @@ +This document provides information for the BPF subsystem about various +workflows related to reporting bugs, submitting patches, and queueing +patches for stable kernels. + +For general information about submitting patches, please refer to +Documentation/process/. This document only describes additional specifics +related to BPF. + +Reporting bugs: +--------------- + +Q: How do I report bugs for BPF kernel code? + +A: Since all BPF kernel development as well as bpftool and iproute2 BPF + loader development happens through the netdev kernel mailing list, + please report any found issues around BPF to the following mailing + list: + + netdev@vger.kernel.org + + This may also include issues related to XDP, BPF tracing, etc. + + Given netdev has a high volume of traffic, please also add the BPF + maintainers to Cc (from kernel MAINTAINERS file): + + Alexei Starovoitov <ast@kernel.org> + Daniel Borkmann <daniel@iogearbox.net> + + In case a buggy commit has already been identified, make sure to keep + the actual commit authors in Cc as well for the report. They can + typically be identified through the kernel's git tree. + + Please do *not* report BPF issues to bugzilla.kernel.org since it + is a guarantee that the reported issue will be overlooked. + +Submitting patches: +------------------- + +Q: To which mailing list do I need to submit my BPF patches? + +A: Please submit your BPF patches to the netdev kernel mailing list: + + netdev@vger.kernel.org + + Historically, BPF came out of networking and has always been maintained + by the kernel networking community. Although these days BPF touches + many other subsystems as well, the patches are still routed mainly + through the networking community. + + In case your patch has changes in various different subsystems (e.g. + tracing, security, etc), make sure to Cc the related kernel mailing + lists and maintainers from there as well, so they are able to review + the changes and provide their Acked-by's to the patches. + +Q: Where can I find patches currently under discussion for BPF subsystem? + +A: All patches that are Cc'ed to netdev are queued for review under netdev + patchwork project: + + http://patchwork.ozlabs.org/project/netdev/list/ + + Those patches which target BPF, are assigned to a 'bpf' delegate for + further processing from BPF maintainers. The current queue with + patches under review can be found at: + + https://patchwork.ozlabs.org/project/netdev/list/?delegate=77147 + + Once the patches have been reviewed by the BPF community as a whole + and approved by the BPF maintainers, their status in patchwork will be + changed to 'Accepted' and the submitter will be notified by mail. This + means that the patches look good from a BPF perspective and have been + applied to one of the two BPF kernel trees. + + In case feedback from the community requires a respin of the patches, + their status in patchwork will be set to 'Changes Requested', and purged + from the current review queue. Likewise for cases where patches would + get rejected or are not applicable to the BPF trees (but assigned to + the 'bpf' delegate). + +Q: How do the changes make their way into Linux? + +A: There are two BPF kernel trees (git repositories). Once patches have + been accepted by the BPF maintainers, they will be applied to one + of the two BPF trees: + + https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/ + https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/ + + The bpf tree itself is for fixes only, whereas bpf-next for features, + cleanups or other kind of improvements ("next-like" content). This is + analogous to net and net-next trees for networking. Both bpf and + bpf-next will only have a master branch in order to simplify against + which branch patches should get rebased to. + + Accumulated BPF patches in the bpf tree will regularly get pulled + into the net kernel tree. Likewise, accumulated BPF patches accepted + into the bpf-next tree will make their way into net-next tree. net and + net-next are both run by David S. Miller. From there, they will go + into the kernel mainline tree run by Linus Torvalds. To read up on the + process of net and net-next being merged into the mainline tree, see + the netdev FAQ under: + + Documentation/networking/netdev-FAQ.txt + + Occasionally, to prevent merge conflicts, we might send pull requests + to other trees (e.g. tracing) with a small subset of the patches, but + net and net-next are always the main trees targeted for integration. + + The pull requests will contain a high-level summary of the accumulated + patches and can be searched on netdev kernel mailing list through the + following subject lines (yyyy-mm-dd is the date of the pull request): + + pull-request: bpf yyyy-mm-dd + pull-request: bpf-next yyyy-mm-dd + +Q: How do I indicate which tree (bpf vs. bpf-next) my patch should be + applied to? + +A: The process is the very same as described in the netdev FAQ, so + please read up on it. The subject line must indicate whether the + patch is a fix or rather "next-like" content in order to let the + maintainers know whether it is targeted at bpf or bpf-next. + + For fixes eventually landing in bpf -> net tree, the subject must + look like: + + git format-patch --subject-prefix='PATCH bpf' start..finish + + For features/improvements/etc that should eventually land in + bpf-next -> net-next, the subject must look like: + + git format-patch --subject-prefix='PATCH bpf-next' start..finish + + If unsure whether the patch or patch series should go into bpf + or net directly, or bpf-next or net-next directly, it is not a + problem either if the subject line says net or net-next as target. + It is eventually up to the maintainers to do the delegation of + the patches. + + If it is clear that patches should go into bpf or bpf-next tree, + please make sure to rebase the patches against those trees in + order to reduce potential conflicts. + + In case the patch or patch series has to be reworked and sent out + again in a second or later revision, it is also required to add a + version number (v2, v3, ...) into the subject prefix: + + git format-patch --subject-prefix='PATCH net-next v2' start..finish + + When changes have been requested to the patch series, always send the + whole patch series again with the feedback incorporated (never send + individual diffs on top of the old series). + +Q: What does it mean when a patch gets applied to bpf or bpf-next tree? + +A: It means that the patch looks good for mainline inclusion from + a BPF point of view. + + Be aware that this is not a final verdict that the patch will + automatically get accepted into net or net-next trees eventually: + + On the netdev kernel mailing list reviews can come in at any point + in time. If discussions around a patch conclude that they cannot + get included as-is, we will either apply a follow-up fix or drop + them from the trees entirely. Therefore, we also reserve to rebase + the trees when deemed necessary. After all, the purpose of the tree + is to i) accumulate and stage BPF patches for integration into trees + like net and net-next, and ii) run extensive BPF test suite and + workloads on the patches before they make their way any further. + + Once the BPF pull request was accepted by David S. Miller, then + the patches end up in net or net-next tree, respectively, and + make their way from there further into mainline. Again, see the + netdev FAQ for additional information e.g. on how often they are + merged to mainline. + +Q: How long do I need to wait for feedback on my BPF patches? + +A: We try to keep the latency low. The usual time to feedback will + be around 2 or 3 business days. It may vary depending on the + complexity of changes and current patch load. + +Q: How often do you send pull requests to major kernel trees like + net or net-next? + +A: Pull requests will be sent out rather often in order to not + accumulate too many patches in bpf or bpf-next. + + As a rule of thumb, expect pull requests for each tree regularly + at the end of the week. In some cases pull requests could additionally + come also in the middle of the week depending on the current patch + load or urgency. + +Q: Are patches applied to bpf-next when the merge window is open? + +A: For the time when the merge window is open, bpf-next will not be + processed. This is roughly analogous to net-next patch processing, + so feel free to read up on the netdev FAQ about further details. + + During those two weeks of merge window, we might ask you to resend + your patch series once bpf-next is open again. Once Linus released + a v*-rc1 after the merge window, we continue processing of bpf-next. + + For non-subscribers to kernel mailing lists, there is also a status + page run by David S. Miller on net-next that provides guidance: + + http://vger.kernel.org/~davem/net-next.html + +Q: I made a BPF verifier change, do I need to add test cases for + BPF kernel selftests? + +A: If the patch has changes to the behavior of the verifier, then yes, + it is absolutely necessary to add test cases to the BPF kernel + selftests suite. If they are not present and we think they are + needed, then we might ask for them before accepting any changes. + + In particular, test_verifier.c is tracking a high number of BPF test + cases, including a lot of corner cases that LLVM BPF back end may + generate out of the restricted C code. Thus, adding test cases is + absolutely crucial to make sure future changes do not accidentally + affect prior use-cases. Thus, treat those test cases as: verifier + behavior that is not tracked in test_verifier.c could potentially + be subject to change. + +Q: When should I add code to samples/bpf/ and when to BPF kernel + selftests? + +A: In general, we prefer additions to BPF kernel selftests rather than + samples/bpf/. The rationale is very simple: kernel selftests are + regularly run by various bots to test for kernel regressions. + + The more test cases we add to BPF selftests, the better the coverage + and the less likely it is that those could accidentally break. It is + not that BPF kernel selftests cannot demo how a specific feature can + be used. + + That said, samples/bpf/ may be a good place for people to get started, + so it might be advisable that simple demos of features could go into + samples/bpf/, but advanced functional and corner-case testing rather + into kernel selftests. + + If your sample looks like a test case, then go for BPF kernel selftests + instead! + +Q: When should I add code to the bpftool? + +A: The main purpose of bpftool (under tools/bpf/bpftool/) is to provide + a central user space tool for debugging and introspection of BPF programs + and maps that are active in the kernel. If UAPI changes related to BPF + enable for dumping additional information of programs or maps, then + bpftool should be extended as well to support dumping them. + +Q: When should I add code to iproute2's BPF loader? + +A: For UAPI changes related to the XDP or tc layer (e.g. cls_bpf), the + convention is that those control-path related changes are added to + iproute2's BPF loader as well from user space side. This is not only + useful to have UAPI changes properly designed to be usable, but also + to make those changes available to a wider user base of major + downstream distributions. + +Q: Do you accept patches as well for iproute2's BPF loader? + +A: Patches for the iproute2's BPF loader have to be sent to: + + netdev@vger.kernel.org + + While those patches are not processed by the BPF kernel maintainers, + please keep them in Cc as well, so they can be reviewed. + + The official git repository for iproute2 is run by Stephen Hemminger + and can be found at: + + https://git.kernel.org/pub/scm/linux/kernel/git/shemminger/iproute2.git/ + + The patches need to have a subject prefix of '[PATCH iproute2 master]' + or '[PATCH iproute2 net-next]'. 'master' or 'net-next' describes the + target branch where the patch should be applied to. Meaning, if kernel + changes went into the net-next kernel tree, then the related iproute2 + changes need to go into the iproute2 net-next branch, otherwise they + can be targeted at master branch. The iproute2 net-next branch will get + merged into the master branch after the current iproute2 version from + master has been released. + + Like BPF, the patches end up in patchwork under the netdev project and + are delegated to 'shemminger' for further processing: + + http://patchwork.ozlabs.org/project/netdev/list/?delegate=389 + +Q: What is the minimum requirement before I submit my BPF patches? + +A: When submitting patches, always take the time and properly test your + patches *prior* to submission. Never rush them! If maintainers find + that your patches have not been properly tested, it is a good way to + get them grumpy. Testing patch submissions is a hard requirement! + + Note, fixes that go to bpf tree *must* have a Fixes: tag included. The + same applies to fixes that target bpf-next, where the affected commit + is in net-next (or in some cases bpf-next). The Fixes: tag is crucial + in order to identify follow-up commits and tremendously helps for people + having to do backporting, so it is a must have! + + We also don't accept patches with an empty commit message. Take your + time and properly write up a high quality commit message, it is + essential! + + Think about it this way: other developers looking at your code a month + from now need to understand *why* a certain change has been done that + way, and whether there have been flaws in the analysis or assumptions + that the original author did. Thus providing a proper rationale and + describing the use-case for the changes is a must. + + Patch submissions with >1 patch must have a cover letter which includes + a high level description of the series. This high level summary will + then be placed into the merge commit by the BPF maintainers such that + it is also accessible from the git log for future reference. + +Q: What do I need to consider when adding a new instruction or feature + that would require BPF JIT and/or LLVM integration as well? + +A: We try hard to keep all BPF JITs up to date such that the same user + experience can be guaranteed when running BPF programs on different + architectures without having the program punt to the less efficient + interpreter in case the in-kernel BPF JIT is enabled. + + If you are unable to implement or test the required JIT changes for + certain architectures, please work together with the related BPF JIT + developers in order to get the feature implemented in a timely manner. + Please refer to the git log (arch/*/net/) to locate the necessary + people for helping out. + + Also always make sure to add BPF test cases (e.g. test_bpf.c and + test_verifier.c) for new instructions, so that they can receive + broad test coverage and help run-time testing the various BPF JITs. + + In case of new BPF instructions, once the changes have been accepted + into the Linux kernel, please implement support into LLVM's BPF back + end. See LLVM section below for further information. + +Stable submission: +------------------ + +Q: I need a specific BPF commit in stable kernels. What should I do? + +A: In case you need a specific fix in stable kernels, first check whether + the commit has already been applied in the related linux-*.y branches: + + https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/ + + If not the case, then drop an email to the BPF maintainers with the + netdev kernel mailing list in Cc and ask for the fix to be queued up: + + netdev@vger.kernel.org + + The process in general is the same as on netdev itself, see also the + netdev FAQ document. + +Q: Do you also backport to kernels not currently maintained as stable? + +A: No. If you need a specific BPF commit in kernels that are currently not + maintained by the stable maintainers, then you are on your own. + + The current stable and longterm stable kernels are all listed here: + + https://www.kernel.org/ + +Q: The BPF patch I am about to submit needs to go to stable as well. What + should I do? + +A: The same rules apply as with netdev patch submissions in general, see + netdev FAQ under: + + Documentation/networking/netdev-FAQ.txt + + Never add "Cc: stable@vger.kernel.org" to the patch description, but + ask the BPF maintainers to queue the patches instead. This can be done + with a note, for example, under the "---" part of the patch which does + not go into the git log. Alternatively, this can be done as a simple + request by mail instead. + +Q: Where do I find currently queued BPF patches that will be submitted + to stable? + +A: Once patches that fix critical bugs got applied into the bpf tree, they + are queued up for stable submission under: + + http://patchwork.ozlabs.org/bundle/bpf/stable/?state=* + + They will be on hold there at minimum until the related commit made its + way into the mainline kernel tree. + + After having been under broader exposure, the queued patches will be + submitted by the BPF maintainers to the stable maintainers. + +Testing patches: +---------------- + +Q: Which BPF kernel selftests version should I run my kernel against? + +A: If you run a kernel xyz, then always run the BPF kernel selftests from + that kernel xyz as well. Do not expect that the BPF selftest from the + latest mainline tree will pass all the time. + + In particular, test_bpf.c and test_verifier.c have a large number of + test cases and are constantly updated with new BPF test sequences, or + existing ones are adapted to verifier changes e.g. due to verifier + becoming smarter and being able to better track certain things. + +LLVM: +----- + +Q: Where do I find LLVM with BPF support? + +A: The BPF back end for LLVM is upstream in LLVM since version 3.7.1. + + All major distributions these days ship LLVM with BPF back end enabled, + so for the majority of use-cases it is not required to compile LLVM by + hand anymore, just install the distribution provided package. + + LLVM's static compiler lists the supported targets through 'llc --version', + make sure BPF targets are listed. Example: + + $ llc --version + LLVM (http://llvm.org/): + LLVM version 6.0.0svn + Optimized build. + Default target: x86_64-unknown-linux-gnu + Host CPU: skylake + + Registered Targets: + bpf - BPF (host endian) + bpfeb - BPF (big endian) + bpfel - BPF (little endian) + x86 - 32-bit X86: Pentium-Pro and above + x86-64 - 64-bit X86: EM64T and AMD64 + + For developers in order to utilize the latest features added to LLVM's + BPF back end, it is advisable to run the latest LLVM releases. Support + for new BPF kernel features such as additions to the BPF instruction + set are often developed together. + + All LLVM releases can be found at: http://releases.llvm.org/ + +Q: Got it, so how do I build LLVM manually anyway? + +A: You need cmake and gcc-c++ as build requisites for LLVM. Once you have + that set up, proceed with building the latest LLVM and clang version + from the git repositories: + + $ git clone http://llvm.org/git/llvm.git + $ cd llvm/tools + $ git clone --depth 1 http://llvm.org/git/clang.git + $ cd ..; mkdir build; cd build + $ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86" \ + -DBUILD_SHARED_LIBS=OFF \ + -DCMAKE_BUILD_TYPE=Release \ + -DLLVM_BUILD_RUNTIME=OFF + $ make -j $(getconf _NPROCESSORS_ONLN) + + The built binaries can then be found in the build/bin/ directory, where + you can point the PATH variable to. + +Q: Should I notify BPF kernel maintainers about issues in LLVM's BPF code + generation back end or about LLVM generated code that the verifier + refuses to accept? + +A: Yes, please do! LLVM's BPF back end is a key piece of the whole BPF + infrastructure and it ties deeply into verification of programs from the + kernel side. Therefore, any issues on either side need to be investigated + and fixed whenever necessary. + + Therefore, please make sure to bring them up at netdev kernel mailing + list and Cc BPF maintainers for LLVM and kernel bits: + + Yonghong Song <yhs@fb.com> + Alexei Starovoitov <ast@kernel.org> + Daniel Borkmann <daniel@iogearbox.net> + + LLVM also has an issue tracker where BPF related bugs can be found: + + https://bugs.llvm.org/buglist.cgi?quicksearch=bpf + + However, it is better to reach out through mailing lists with having + maintainers in Cc. + +Q: I have added a new BPF instruction to the kernel, how can I integrate + it into LLVM? + +A: LLVM has a -mcpu selector for the BPF back end in order to allow the + selection of BPF instruction set extensions. By default the 'generic' + processor target is used, which is the base instruction set (v1) of BPF. + + LLVM has an option to select -mcpu=probe where it will probe the host + kernel for supported BPF instruction set extensions and selects the + optimal set automatically. + + For cross-compilation, a specific version can be select manually as well. + + $ llc -march bpf -mcpu=help + Available CPUs for this target: + + generic - Select the generic processor. + probe - Select the probe processor. + v1 - Select the v1 processor. + v2 - Select the v2 processor. + [...] + + Newly added BPF instructions to the Linux kernel need to follow the same + scheme, bump the instruction set version and implement probing for the + extensions such that -mcpu=probe users can benefit from the optimization + transparently when upgrading their kernels. + + If you are unable to implement support for the newly added BPF instruction + please reach out to BPF developers for help. + + By the way, the BPF kernel selftests run with -mcpu=probe for better + test coverage. + +Happy BPF hacking! diff --git a/Documentation/devicetree/bindings/net/brcm,bcm7445-switch-v4.0.txt b/Documentation/devicetree/bindings/net/brcm,bcm7445-switch-v4.0.txt index 9a734d8..b7336b9 100644 --- a/Documentation/devicetree/bindings/net/brcm,bcm7445-switch-v4.0.txt +++ b/Documentation/devicetree/bindings/net/brcm,bcm7445-switch-v4.0.txt @@ -2,7 +2,10 @@ Required properties: -- compatible: should be "brcm,bcm7445-switch-v4.0" or "brcm,bcm7278-switch-v4.0" +- compatible: should be one of + "brcm,bcm7445-switch-v4.0" + "brcm,bcm7278-switch-v4.0" + "brcm,bcm7278-switch-v4.8" - reg: addresses and length of the register sets for the device, must be 6 pairs of register addresses and lengths - interrupts: interrupts for the devices, must be two interrupts diff --git a/Documentation/devicetree/bindings/net/can/can-transceiver.txt b/Documentation/devicetree/bindings/net/can/can-transceiver.txt new file mode 100644 index 0000000..0011f53 --- /dev/null +++ b/Documentation/devicetree/bindings/net/can/can-transceiver.txt @@ -0,0 +1,24 @@ +Generic CAN transceiver Device Tree binding +------------------------------ + +CAN transceiver typically limits the max speed in standard CAN and CAN FD +modes. Typically these limitations are static and the transceivers themselves +provide no way to detect this limitation at runtime. For this situation, +the "can-transceiver" node can be used. + +Required Properties: + max-bitrate: a positive non 0 value that determines the max + speed that CAN/CAN-FD can run. Any other value + will be ignored. + +Examples: + +Based on Texas Instrument's TCAN1042HGV CAN Transceiver + +m_can0 { + .... + can-transceiver { + max-bitrate = <5000000>; + }; + ... +}; diff --git a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt index 56d6cc3..bfc0c43 100644 --- a/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt +++ b/Documentation/devicetree/bindings/net/can/fsl-flexcan.txt @@ -18,6 +18,12 @@ Optional properties: - xceiver-supply: Regulator that powers the CAN transceiver +- big-endian: This means the registers of FlexCAN controller are big endian. + This is optional property.i.e. if this property is not present in + device tree node then controller is assumed to be little endian. + if this property is present then controller is assumed to be big + endian. + Example: can@1c000 { diff --git a/Documentation/devicetree/bindings/net/can/m_can.txt b/Documentation/devicetree/bindings/net/can/m_can.txt index 63e9042..ed61438 100644 --- a/Documentation/devicetree/bindings/net/can/m_can.txt +++ b/Documentation/devicetree/bindings/net/can/m_can.txt @@ -43,6 +43,11 @@ Required properties: Please refer to 2.4.1 Message RAM Configuration in Bosch M_CAN user manual for details. +Optional Subnode: +- can-transceiver : Can-transceiver subnode describing maximum speed + that can be used for CAN/CAN-FD modes. See + Documentation/devicetree/bindings/net/can/can-transceiver.txt + for details. Example: SoC dtsi: m_can1: can@20e8000 { @@ -63,4 +68,8 @@ Board dts: pinctrl-names = "default"; pinctrl-0 = <&pinctrl_m_can1>; status = "enabled"; + + can-transceiver { + max-bitrate = <5000000>; + }; }; diff --git a/Documentation/devicetree/bindings/net/can/rcar_can.txt b/Documentation/devicetree/bindings/net/can/rcar_can.txt index 06bb7cc..94a7f33 100644 --- a/Documentation/devicetree/bindings/net/can/rcar_can.txt +++ b/Documentation/devicetree/bindings/net/can/rcar_can.txt @@ -2,7 +2,9 @@ Renesas R-Car CAN controller Device Tree Bindings ------------------------------------------------- Required properties: -- compatible: "renesas,can-r8a7778" if CAN controller is a part of R8A7778 SoC. +- compatible: "renesas,can-r8a7743" if CAN controller is a part of R8A7743 SoC. + "renesas,can-r8a7745" if CAN controller is a part of R8A7745 SoC. + "renesas,can-r8a7778" if CAN controller is a part of R8A7778 SoC. "renesas,can-r8a7779" if CAN controller is a part of R8A7779 SoC. "renesas,can-r8a7790" if CAN controller is a part of R8A7790 SoC. "renesas,can-r8a7791" if CAN controller is a part of R8A7791 SoC. @@ -12,7 +14,8 @@ Required properties: "renesas,can-r8a7795" if CAN controller is a part of R8A7795 SoC. "renesas,can-r8a7796" if CAN controller is a part of R8A7796 SoC. "renesas,rcar-gen1-can" for a generic R-Car Gen1 compatible device. - "renesas,rcar-gen2-can" for a generic R-Car Gen2 compatible device. + "renesas,rcar-gen2-can" for a generic R-Car Gen2 or RZ/G1 + compatible device. "renesas,rcar-gen3-can" for a generic R-Car Gen3 compatible device. When compatible with the generic version, nodes must list the SoC-specific version corresponding to the platform first diff --git a/Documentation/devicetree/bindings/net/cortina,gemini-ethernet.txt b/Documentation/devicetree/bindings/net/cortina,gemini-ethernet.txt new file mode 100644 index 0000000..6c55998 --- /dev/null +++ b/Documentation/devicetree/bindings/net/cortina,gemini-ethernet.txt @@ -0,0 +1,92 @@ +Cortina Systems Gemini Ethernet Controller +========================================== + +This ethernet controller is found in the Gemini SoC family: +StorLink SL3512 and SL3516, also known as Cortina Systems +CS3512 and CS3516. + +Required properties: +- compatible: must be "cortina,gemini-ethernet" +- reg: must contain the global registers and the V-bit and A-bit + memory areas, in total three register sets. +- syscon: a phandle to the system controller +- #address-cells: must be specified, must be <1> +- #size-cells: must be specified, must be <1> +- ranges: should be state like this giving a 1:1 address translation + for the subnodes + +The subnodes represents the two ethernet ports in this device. +They are not independent of each other since they share resources +in the parent node, and are thus children. + +Required subnodes: +- port0: contains the resources for ethernet port 0 +- port1: contains the resources for ethernet port 1 + +Required subnode properties: +- compatible: must be "cortina,gemini-ethernet-port" +- reg: must contain two register areas: the DMA/TOE memory and + the GMAC memory area of the port +- interrupts: should contain the interrupt line of the port. + this is nominally a level interrupt active high. +- resets: this must provide an SoC-integrated reset line for + the port. +- clocks: this should contain a handle to the PCLK clock for + clocking the silicon in this port +- clock-names: must be "PCLK" + +Optional subnode properties: +- phy-mode: see ethernet.txt +- phy-handle: see ethernet.txt + +Example: + +mdio-bus { + (...) + phy0: ethernet-phy@1 { + reg = <1>; + device_type = "ethernet-phy"; + }; + phy1: ethernet-phy@3 { + reg = <3>; + device_type = "ethernet-phy"; + }; +}; + + +ethernet@60000000 { + compatible = "cortina,gemini-ethernet"; + reg = <0x60000000 0x4000>, /* Global registers, queue */ + <0x60004000 0x2000>, /* V-bit */ + <0x60006000 0x2000>; /* A-bit */ + syscon = <&syscon>; + #address-cells = <1>; + #size-cells = <1>; + ranges; + + gmac0: ethernet-port@0 { + compatible = "cortina,gemini-ethernet-port"; + reg = <0x60008000 0x2000>, /* Port 0 DMA/TOE */ + <0x6000a000 0x2000>; /* Port 0 GMAC */ + interrupt-parent = <&intcon>; + interrupts = <1 IRQ_TYPE_LEVEL_HIGH>; + resets = <&syscon GEMINI_RESET_GMAC0>; + clocks = <&syscon GEMINI_CLK_GATE_GMAC0>; + clock-names = "PCLK"; + phy-mode = "rgmii"; + phy-handle = <&phy0>; + }; + + gmac1: ethernet-port@1 { + compatible = "cortina,gemini-ethernet-port"; + reg = <0x6000c000 0x2000>, /* Port 1 DMA/TOE */ + <0x6000e000 0x2000>; /* Port 1 GMAC */ + interrupt-parent = <&intcon>; + interrupts = <2 IRQ_TYPE_LEVEL_HIGH>; + resets = <&syscon GEMINI_RESET_GMAC1>; + clocks = <&syscon GEMINI_CLK_GATE_GMAC1>; + clock-names = "PCLK"; + phy-mode = "rgmii"; + phy-handle = <&phy1>; + }; +}; diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt index f0dc944..2d41fb9 100644 --- a/Documentation/devicetree/bindings/net/fsl-fec.txt +++ b/Documentation/devicetree/bindings/net/fsl-fec.txt @@ -59,7 +59,7 @@ ethernet@83fec000 { reg = <0x83fec000 0x4000>; interrupts = <87>; phy-mode = "mii"; - phy-reset-gpios = <&gpio2 14 0>; /* GPIO2_14 */ + phy-reset-gpios = <&gpio2 14 GPIO_ACTIVE_LOW>; /* GPIO2_14 */ local-mac-address = [00 04 9F 01 1B B9]; phy-supply = <®_fec_supply>; }; @@ -71,7 +71,7 @@ ethernet@83fec000 { reg = <0x83fec000 0x4000>; interrupts = <87>; phy-mode = "mii"; - phy-reset-gpios = <&gpio2 14 0>; /* GPIO2_14 */ + phy-reset-gpios = <&gpio2 14 GPIO_ACTIVE_LOW>; /* GPIO2_14 */ local-mac-address = [00 04 9F 01 1B B9]; phy-supply = <®_fec_supply>; phy-handle = <ðphy>; diff --git a/Documentation/devicetree/bindings/net/ieee802154/adf7242.txt b/Documentation/devicetree/bindings/net/ieee802154/adf7242.txt index dea5124..d24172c 100644 --- a/Documentation/devicetree/bindings/net/ieee802154/adf7242.txt +++ b/Documentation/devicetree/bindings/net/ieee802154/adf7242.txt @@ -1,7 +1,7 @@ * ADF7242 IEEE 802.15.4 * Required properties: - - compatible: should be "adi,adf7242" + - compatible: should be "adi,adf7242", "adi,adf7241" - spi-max-frequency: maximal bus speed (12.5 MHz) - reg: the chipselect index - interrupts: the interrupt generated by the device via pin IRQ1. diff --git a/Documentation/devicetree/bindings/net/mediatek-net.txt b/Documentation/devicetree/bindings/net/mediatek-net.txt index 214eaa9..53c13ee 100644 --- a/Documentation/devicetree/bindings/net/mediatek-net.txt +++ b/Documentation/devicetree/bindings/net/mediatek-net.txt @@ -28,7 +28,7 @@ Required properties: - mediatek,sgmiisys: phandle to the syscon node that handles the SGMII setup which is required for those SoCs equipped with SGMII such as MT7622 SoC. - mediatek,pctl: phandle to the syscon node that handles the ports slew rate - and driver current + and driver current: only for MT2701 and MT7623 SoC Optional properties: - interrupt-parent: Should be the phandle for the interrupt controller diff --git a/Documentation/devicetree/bindings/net/phy.txt b/Documentation/devicetree/bindings/net/phy.txt index 77d0b2a..d2169a5 100644 --- a/Documentation/devicetree/bindings/net/phy.txt +++ b/Documentation/devicetree/bindings/net/phy.txt @@ -53,6 +53,14 @@ Optional Properties: to ensure the integrated PHY is used. The absence of this property indicates the muxers should be configured so that the external PHY is used. +- reset-gpios: The GPIO phandle and specifier for the PHY reset signal. + +- reset-assert-us: Delay after the reset was asserted in microseconds. + If this property is missing the delay will be skipped. + +- reset-deassert-us: Delay after the reset was deasserted in microseconds. + If this property is missing the delay will be skipped. + Example: ethernet-phy@0 { @@ -60,4 +68,8 @@ ethernet-phy@0 { interrupt-parent = <&PIC>; interrupts = <35 IRQ_TYPE_EDGE_RISING>; reg = <0>; + + reset-gpios = <&gpio1 4 GPIO_ACTIVE_LOW>; + reset-assert-us = <1000>; + reset-deassert-us = <2000>; }; diff --git a/Documentation/devicetree/bindings/net/sff,sfp.txt b/Documentation/devicetree/bindings/net/sff,sfp.txt index 60e970c..f1c441b 100644 --- a/Documentation/devicetree/bindings/net/sff,sfp.txt +++ b/Documentation/devicetree/bindings/net/sff,sfp.txt @@ -3,7 +3,9 @@ Transceiver Required properties: -- compatible : must be "sff,sfp" +- compatible : must be one of + "sff,sfp" for SFP modules + "sff,sff" for soldered down SFF modules Optional Properties: @@ -11,7 +13,8 @@ Optional Properties: interface - mod-def0-gpios : GPIO phandle and a specifier of the MOD-DEF0 (AKA Mod_ABS) - module presence input gpio signal, active (module absent) high + module presence input gpio signal, active (module absent) high. Must + not be present for SFF modules - los-gpios : GPIO phandle and a specifier of the Receiver Loss of Signal Indication input gpio signal, active (signal lost) high @@ -24,10 +27,11 @@ Optional Properties: - rate-select0-gpios : GPIO phandle and a specifier of the Rx Signaling Rate Select (AKA RS0) output gpio signal, low: low Rx rate, high: high Rx rate + Must not be present for SFF modules - rate-select1-gpios : GPIO phandle and a specifier of the Tx Signaling Rate Select (AKA RS1) output gpio signal (SFP+ only), low: low Tx rate, high: - high Tx rate + high Tx rate. Must not be present for SFF modules Example #1: Direct serdes to SFP connection diff --git a/Documentation/devicetree/bindings/net/socionext,uniphier-ave4.txt b/Documentation/devicetree/bindings/net/socionext,uniphier-ave4.txt new file mode 100644 index 0000000..270ea4e --- /dev/null +++ b/Documentation/devicetree/bindings/net/socionext,uniphier-ave4.txt @@ -0,0 +1,48 @@ +* Socionext AVE ethernet controller + +This describes the devicetree bindings for AVE ethernet controller +implemented on Socionext UniPhier SoCs. + +Required properties: + - compatible: Should be + - "socionext,uniphier-pro4-ave4" : for Pro4 SoC + - "socionext,uniphier-pxs2-ave4" : for PXs2 SoC + - "socionext,uniphier-ld11-ave4" : for LD11 SoC + - "socionext,uniphier-ld20-ave4" : for LD20 SoC + - reg: Address where registers are mapped and size of region. + - interrupts: Should contain the MAC interrupt. + - phy-mode: See ethernet.txt in the same directory. Allow to choose + "rgmii", "rmii", or "mii" according to the PHY. + - phy-handle: Should point to the external phy device. + See ethernet.txt file in the same directory. + - clocks: A phandle to the clock for the MAC. + +Optional properties: + - resets: A phandle to the reset control for the MAC. + - local-mac-address: See ethernet.txt in the same directory. + +Required subnode: + - mdio: A container for child nodes representing phy nodes. + See phy.txt in the same directory. + +Example: + + ether: ethernet@65000000 { + compatible = "socionext,uniphier-ld20-ave4"; + reg = <0x65000000 0x8500>; + interrupts = <0 66 4>; + phy-mode = "rgmii"; + phy-handle = <ðphy>; + clocks = <&sys_clk 6>; + resets = <&sys_rst 6>; + local-mac-address = [00 00 00 00 00 00]; + + mdio { + #address-cells = <1>; + #size-cells = <0>; + + ethphy: ethphy@1 { + reg = <1>; + }; + }; + }; diff --git a/Documentation/devicetree/bindings/net/socionext-netsec.txt b/Documentation/devicetree/bindings/net/socionext-netsec.txt new file mode 100644 index 0000000..0cff94f --- /dev/null +++ b/Documentation/devicetree/bindings/net/socionext-netsec.txt @@ -0,0 +1,53 @@ +* Socionext NetSec Ethernet Controller IP + +Required properties: +- compatible: Should be "socionext,synquacer-netsec" +- reg: Address and length of the control register area, followed by the + address and length of the EEPROM holding the MAC address and + microengine firmware +- interrupts: Should contain ethernet controller interrupt +- clocks: phandle to the PHY reference clock +- clock-names: Should be "phy_ref_clk" +- phy-mode: See ethernet.txt file in the same directory +- phy-handle: See ethernet.txt in the same directory. + +- mdio device tree subnode: When the Netsec has a phy connected to its local + mdio, there must be device tree subnode with the following + required properties: + + - #address-cells: Must be <1>. + - #size-cells: Must be <0>. + + For each phy on the mdio bus, there must be a node with the following + fields: + - compatible: Refer to phy.txt + - reg: phy id used to communicate to phy. + +Optional properties: (See ethernet.txt file in the same directory) +- dma-coherent: Boolean property, must only be present if memory + accesses performed by the device are cache coherent. +- local-mac-address: See ethernet.txt in the same directory. +- mac-address: See ethernet.txt in the same directory. +- max-speed: See ethernet.txt in the same directory. +- max-frame-size: See ethernet.txt in the same directory. + +Example: + eth0: ethernet@522d0000 { + compatible = "socionext,synquacer-netsec"; + reg = <0 0x522d0000 0x0 0x10000>, <0 0x10000000 0x0 0x10000>; + interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>; + clocks = <&clk_netsec>; + clock-names = "phy_ref_clk"; + phy-mode = "rgmii"; + max-speed = <1000>; + max-frame-size = <9000>; + phy-handle = <&phy1>; + + mdio { + #address-cells = <1>; + #size-cells = <0>; + phy1: ethernet-phy@1 { + compatible = "ethernet-phy-ieee802.3-c22"; + reg = <1>; + }; + }; diff --git a/Documentation/devicetree/bindings/net/ti,wilink-st.txt b/Documentation/devicetree/bindings/net/ti-bluetooth.txt index 1649c1f..6d03ff8 100644 --- a/Documentation/devicetree/bindings/net/ti,wilink-st.txt +++ b/Documentation/devicetree/bindings/net/ti-bluetooth.txt @@ -1,10 +1,18 @@ -TI WiLink 7/8 (wl12xx/wl18xx) Shared Transport BT/FM/GPS devices +Texas Instruments Bluetooth Chips +--------------------------------- + +This documents the binding structure and common properties for serial +attached TI Bluetooth devices. The following chips are included in this +binding: + +* TI CC256x Bluetooth devices +* TI WiLink 7/8 (wl12xx/wl18xx) Shared Transport BT/FM/GPS devices TI WiLink devices have a UART interface for providing Bluetooth, FM radio, and GPS over what's called "shared transport". The shared transport is standard BT HCI protocol with additional channels for the other functions. -These devices also have a separate WiFi interface as described in +TI WiLink devices also have a separate WiFi interface as described in wireless/ti,wlcore.txt. This bindings follows the UART slave device binding in @@ -12,6 +20,7 @@ This bindings follows the UART slave device binding in Required properties: - compatible: should be one of the following: + "ti,cc2560" "ti,wl1271-st" "ti,wl1273-st" "ti,wl1281-st" @@ -32,6 +41,9 @@ Optional properties: See ../clocks/clock-bindings.txt for details. - clock-names : Must include the following entry: "ext_clock" (External clock provided to the TI combo chip). + - nvmem-cells: phandle to nvmem data cell that contains a 6 byte BD address + with the most significant byte first (big-endian). + - nvmem-cell-names: "bd-address" (required when nvmem-cells is specified) Example: @@ -43,5 +55,7 @@ Example: enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>; clocks = <&clk32k_wl18xx>; clock-names = "ext_clock"; + nvmem-cells = <&bd_address>; + nvmem-cell-names = "bd-address"; }; }; diff --git a/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt b/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt new file mode 100644 index 0000000..0c17a0e --- /dev/null +++ b/Documentation/devicetree/bindings/net/wireless/mediatek,mt76.txt @@ -0,0 +1,32 @@ +* MediaTek mt76xx devices + +This node provides properties for configuring the MediaTek mt76xx wireless +device. The node is expected to be specified as a child node of the PCI +controller to which the wireless chip is connected. + +Optional properties: + +- mac-address: See ethernet.txt in the parent directory +- local-mac-address: See ethernet.txt in the parent directory +- ieee80211-freq-limit: See ieee80211.txt +- mediatek,mtd-eeprom: Specify a MTD partition + offset containing EEPROM data + +Optional nodes: +- led: Properties for a connected LED + Optional properties: + - led-sources: See Documentation/devicetree/bindings/leds/common.txt + +&pcie { + pcie0 { + wifi@0,0 { + compatible = "mediatek,mt76"; + reg = <0x0000 0 0 0 0>; + ieee80211-freq-limit = <5000000 6000000>; + mediatek,mtd-eeprom = <&factory 0x8000>; + + led { + led-sources = <2>; + }; + }; + }; +}; diff --git a/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt b/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt index 74d7f0a..3d2a031 100644 --- a/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt +++ b/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.txt @@ -41,6 +41,9 @@ Optional properties: - qcom,msi_addr: MSI interrupt address. - qcom,msi_base: Base value to add before writing MSI data into MSI address register. +- qcom,ath10k-calibration-variant: string to search for in the board-2.bin + variant list with the same bus and device + specific ids - qcom,ath10k-calibration-data : calibration data + board specific data as an array, the length can vary between hw versions. diff --git a/Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt b/Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt index 4ccb2cd..d096cf4 100644 --- a/Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt +++ b/Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt @@ -195,4 +195,4 @@ External interrupts: fsl,mpc5200-mscan nodes ----------------------- -See file can.txt in this directory. +See file Documentation/devicetree/bindings/powerpc/fsl/mpc5200.txt diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt index 918972b..f4a3246 100644 --- a/Documentation/fault-injection/fault-injection.txt +++ b/Documentation/fault-injection/fault-injection.txt @@ -30,6 +30,12 @@ o fail_mmc_request injects MMC data errors on devices permitted by setting debugfs entries under /sys/kernel/debug/mmc0/fail_mmc_request +o fail_function + + injects error return on specific functions, which are marked by + ALLOW_ERROR_INJECTION() macro, by setting debugfs entries + under /sys/kernel/debug/fail_function. No boot option supported. + Configure fault-injection capabilities behavior ----------------------------------------------- @@ -123,6 +129,29 @@ configuration of fault-injection capabilities. default is 'N', setting it to 'Y' will disable failure injections when dealing with private (address space) futexes. +- /sys/kernel/debug/fail_function/inject: + + Format: { 'function-name' | '!function-name' | '' } + specifies the target function of error injection by name. + If the function name leads '!' prefix, given function is + removed from injection list. If nothing specified ('') + injection list is cleared. + +- /sys/kernel/debug/fail_function/injectable: + + (read only) shows error injectable functions and what type of + error values can be specified. The error type will be one of + below; + - NULL: retval must be 0. + - ERRNO: retval must be -1 to -MAX_ERRNO (-4096). + - ERR_NULL: retval must be 0 or -1 to -MAX_ERRNO (-4096). + +- /sys/kernel/debug/fail_function/<functiuon-name>/retval: + + specifies the "error" return value to inject to the given + function for given function. This will be created when + user specifies new injection entry. + o Boot option In order to inject faults while debugfs is not available (early boot time), @@ -268,6 +297,45 @@ trap "echo 0 > /sys/kernel/debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT echo "Injecting errors into the module $module... (interrupt to stop)" sleep 1000000 +------------------------------------------------------------------------------ + +o Inject open_ctree error while btrfs mount + +#!/bin/bash + +rm -f testfile.img +dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1 +DEVICE=$(losetup --show -f testfile.img) +mkfs.btrfs -f $DEVICE +mkdir -p tmpmnt + +FAILTYPE=fail_function +FAILFUNC=open_ctree +echo $FAILFUNC > /sys/kernel/debug/$FAILTYPE/inject +echo -12 > /sys/kernel/debug/$FAILTYPE/$FAILFUNC/retval +echo N > /sys/kernel/debug/$FAILTYPE/task-filter +echo 100 > /sys/kernel/debug/$FAILTYPE/probability +echo 0 > /sys/kernel/debug/$FAILTYPE/interval +echo -1 > /sys/kernel/debug/$FAILTYPE/times +echo 0 > /sys/kernel/debug/$FAILTYPE/space +echo 1 > /sys/kernel/debug/$FAILTYPE/verbose + +mount -t btrfs $DEVICE tmpmnt +if [ $? -ne 0 ] +then + echo "SUCCESS!" +else + echo "FAILED!" + umount tmpmnt +fi + +echo > /sys/kernel/debug/$FAILTYPE/inject + +rmdir tmpmnt +losetup -d $DEVICE +rm testfile.img + + Tool to run command with failslab or fail_page_alloc ---------------------------------------------------- In order to make it easier to accomplish the tasks mentioned above, we can use diff --git a/Documentation/networking/00-INDEX b/Documentation/networking/00-INDEX index 7a79b35..2b89d91 100644 --- a/Documentation/networking/00-INDEX +++ b/Documentation/networking/00-INDEX @@ -36,8 +36,6 @@ bonding.txt - Linux Ethernet Bonding Driver HOWTO: link aggregation in Linux. bridge.txt - where to get user space programs for ethernet bridging with Linux. -can.txt - - documentation on CAN protocol family. cdc_mbim.txt - 3G/LTE USB modem (Mobile Broadband Interface Model) checksum-offloads.txt @@ -228,6 +226,8 @@ x25.txt - general info on X.25 development. x25-iface.txt - description of the X.25 Packet Layer to LAPB device interface. +xfrm_device.txt + - description of XFRM offload API xfrm_proc.txt - description of the statistics package for XFRM. xfrm_sync.txt diff --git a/Documentation/networking/batman-adv.rst b/Documentation/networking/batman-adv.rst index a342b2c..245fb6c 100644 --- a/Documentation/networking/batman-adv.rst +++ b/Documentation/networking/batman-adv.rst @@ -1,3 +1,5 @@ +.. SPDX-License-Identifier: GPL-2.0 + ========== batman-adv ========== diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst new file mode 100644 index 0000000..d23c51a --- /dev/null +++ b/Documentation/networking/can.rst @@ -0,0 +1,1437 @@ +=================================== +SocketCAN - Controller Area Network +=================================== + +Overview / What is SocketCAN +============================ + +The socketcan package is an implementation of CAN protocols +(Controller Area Network) for Linux. CAN is a networking technology +which has widespread use in automation, embedded devices, and +automotive fields. While there have been other CAN implementations +for Linux based on character devices, SocketCAN uses the Berkeley +socket API, the Linux network stack and implements the CAN device +drivers as network interfaces. The CAN socket API has been designed +as similar as possible to the TCP/IP protocols to allow programmers, +familiar with network programming, to easily learn how to use CAN +sockets. + + +.. _socketcan-motivation: + +Motivation / Why Using the Socket API +===================================== + +There have been CAN implementations for Linux before SocketCAN so the +question arises, why we have started another project. Most existing +implementations come as a device driver for some CAN hardware, they +are based on character devices and provide comparatively little +functionality. Usually, there is only a hardware-specific device +driver which provides a character device interface to send and +receive raw CAN frames, directly to/from the controller hardware. +Queueing of frames and higher-level transport protocols like ISO-TP +have to be implemented in user space applications. Also, most +character-device implementations support only one single process to +open the device at a time, similar to a serial interface. Exchanging +the CAN controller requires employment of another device driver and +often the need for adaption of large parts of the application to the +new driver's API. + +SocketCAN was designed to overcome all of these limitations. A new +protocol family has been implemented which provides a socket interface +to user space applications and which builds upon the Linux network +layer, enabling use all of the provided queueing functionality. A device +driver for CAN controller hardware registers itself with the Linux +network layer as a network device, so that CAN frames from the +controller can be passed up to the network layer and on to the CAN +protocol family module and also vice-versa. Also, the protocol family +module provides an API for transport protocol modules to register, so +that any number of transport protocols can be loaded or unloaded +dynamically. In fact, the can core module alone does not provide any +protocol and cannot be used without loading at least one additional +protocol module. Multiple sockets can be opened at the same time, +on different or the same protocol module and they can listen/send +frames on different or the same CAN IDs. Several sockets listening on +the same interface for frames with the same CAN ID are all passed the +same received matching CAN frames. An application wishing to +communicate using a specific transport protocol, e.g. ISO-TP, just +selects that protocol when opening the socket, and then can read and +write application data byte streams, without having to deal with +CAN-IDs, frames, etc. + +Similar functionality visible from user-space could be provided by a +character device, too, but this would lead to a technically inelegant +solution for a couple of reasons: + +* **Intricate usage:** Instead of passing a protocol argument to + socket(2) and using bind(2) to select a CAN interface and CAN ID, an + application would have to do all these operations using ioctl(2)s. + +* **Code duplication:** A character device cannot make use of the Linux + network queueing code, so all that code would have to be duplicated + for CAN networking. + +* **Abstraction:** In most existing character-device implementations, the + hardware-specific device driver for a CAN controller directly + provides the character device for the application to work with. + This is at least very unusual in Unix systems for both, char and + block devices. For example you don't have a character device for a + certain UART of a serial interface, a certain sound chip in your + computer, a SCSI or IDE controller providing access to your hard + disk or tape streamer device. Instead, you have abstraction layers + which provide a unified character or block device interface to the + application on the one hand, and a interface for hardware-specific + device drivers on the other hand. These abstractions are provided + by subsystems like the tty layer, the audio subsystem or the SCSI + and IDE subsystems for the devices mentioned above. + + The easiest way to implement a CAN device driver is as a character + device without such a (complete) abstraction layer, as is done by most + existing drivers. The right way, however, would be to add such a + layer with all the functionality like registering for certain CAN + IDs, supporting several open file descriptors and (de)multiplexing + CAN frames between them, (sophisticated) queueing of CAN frames, and + providing an API for device drivers to register with. However, then + it would be no more difficult, or may be even easier, to use the + networking framework provided by the Linux kernel, and this is what + SocketCAN does. + +The use of the networking framework of the Linux kernel is just the +natural and most appropriate way to implement CAN for Linux. + + +.. _socketcan-concept: + +SocketCAN Concept +================= + +As described in :ref:`socketcan-motivation` the main goal of SocketCAN is to +provide a socket interface to user space applications which builds +upon the Linux network layer. In contrast to the commonly known +TCP/IP and ethernet networking, the CAN bus is a broadcast-only(!) +medium that has no MAC-layer addressing like ethernet. The CAN-identifier +(can_id) is used for arbitration on the CAN-bus. Therefore the CAN-IDs +have to be chosen uniquely on the bus. When designing a CAN-ECU +network the CAN-IDs are mapped to be sent by a specific ECU. +For this reason a CAN-ID can be treated best as a kind of source address. + + +.. _socketcan-receive-lists: + +Receive Lists +------------- + +The network transparent access of multiple applications leads to the +problem that different applications may be interested in the same +CAN-IDs from the same CAN network interface. The SocketCAN core +module - which implements the protocol family CAN - provides several +high efficient receive lists for this reason. If e.g. a user space +application opens a CAN RAW socket, the raw protocol module itself +requests the (range of) CAN-IDs from the SocketCAN core that are +requested by the user. The subscription and unsubscription of +CAN-IDs can be done for specific CAN interfaces or for all(!) known +CAN interfaces with the can_rx_(un)register() functions provided to +CAN protocol modules by the SocketCAN core (see :ref:`socketcan-core-module`). +To optimize the CPU usage at runtime the receive lists are split up +into several specific lists per device that match the requested +filter complexity for a given use-case. + + +.. _socketcan-local-loopback1: + +Local Loopback of Sent Frames +----------------------------- + +As known from other networking concepts the data exchanging +applications may run on the same or different nodes without any +change (except for the according addressing information): + +.. code:: + + ___ ___ ___ _______ ___ + | _ | | _ | | _ | | _ _ | | _ | + ||A|| ||B|| ||C|| ||A| |B|| ||C|| + |___| |___| |___| |_______| |___| + | | | | | + -----------------(1)- CAN bus -(2)--------------- + +To ensure that application A receives the same information in the +example (2) as it would receive in example (1) there is need for +some kind of local loopback of the sent CAN frames on the appropriate +node. + +The Linux network devices (by default) just can handle the +transmission and reception of media dependent frames. Due to the +arbitration on the CAN bus the transmission of a low prio CAN-ID +may be delayed by the reception of a high prio CAN frame. To +reflect the correct [*]_ traffic on the node the loopback of the sent +data has to be performed right after a successful transmission. If +the CAN network interface is not capable of performing the loopback for +some reason the SocketCAN core can do this task as a fallback solution. +See :ref:`socketcan-local-loopback1` for details (recommended). + +The loopback functionality is enabled by default to reflect standard +networking behaviour for CAN applications. Due to some requests from +the RT-SocketCAN group the loopback optionally may be disabled for each +separate socket. See sockopts from the CAN RAW sockets in :ref:`socketcan-raw-sockets`. + +.. [*] you really like to have this when you're running analyser + tools like 'candump' or 'cansniffer' on the (same) node. + + +.. _socketcan-network-problem-notifications: + +Network Problem Notifications +----------------------------- + +The use of the CAN bus may lead to several problems on the physical +and media access control layer. Detecting and logging of these lower +layer problems is a vital requirement for CAN users to identify +hardware issues on the physical transceiver layer as well as +arbitration problems and error frames caused by the different +ECUs. The occurrence of detected errors are important for diagnosis +and have to be logged together with the exact timestamp. For this +reason the CAN interface driver can generate so called Error Message +Frames that can optionally be passed to the user application in the +same way as other CAN frames. Whenever an error on the physical layer +or the MAC layer is detected (e.g. by the CAN controller) the driver +creates an appropriate error message frame. Error messages frames can +be requested by the user application using the common CAN filter +mechanisms. Inside this filter definition the (interested) type of +errors may be selected. The reception of error messages is disabled +by default. The format of the CAN error message frame is briefly +described in the Linux header file "include/uapi/linux/can/error.h". + + +How to use SocketCAN +==================== + +Like TCP/IP, you first need to open a socket for communicating over a +CAN network. Since SocketCAN implements a new protocol family, you +need to pass PF_CAN as the first argument to the socket(2) system +call. Currently, there are two CAN protocols to choose from, the raw +socket protocol and the broadcast manager (BCM). So to open a socket, +you would write:: + + s = socket(PF_CAN, SOCK_RAW, CAN_RAW); + +and:: + + s = socket(PF_CAN, SOCK_DGRAM, CAN_BCM); + +respectively. After the successful creation of the socket, you would +normally use the bind(2) system call to bind the socket to a CAN +interface (which is different from TCP/IP due to different addressing +- see :ref:`socketcan-concept`). After binding (CAN_RAW) or connecting (CAN_BCM) +the socket, you can read(2) and write(2) from/to the socket or use +send(2), sendto(2), sendmsg(2) and the recv* counterpart operations +on the socket as usual. There are also CAN specific socket options +described below. + +The basic CAN frame structure and the sockaddr structure are defined +in include/linux/can.h: + +.. code-block:: C + + struct can_frame { + canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */ + __u8 can_dlc; /* frame payload length in byte (0 .. 8) */ + __u8 __pad; /* padding */ + __u8 __res0; /* reserved / padding */ + __u8 __res1; /* reserved / padding */ + __u8 data[8] __attribute__((aligned(8))); + }; + +The alignment of the (linear) payload data[] to a 64bit boundary +allows the user to define their own structs and unions to easily access +the CAN payload. There is no given byteorder on the CAN bus by +default. A read(2) system call on a CAN_RAW socket transfers a +struct can_frame to the user space. + +The sockaddr_can structure has an interface index like the +PF_PACKET socket, that also binds to a specific interface: + +.. code-block:: C + + struct sockaddr_can { + sa_family_t can_family; + int can_ifindex; + union { + /* transport protocol class address info (e.g. ISOTP) */ + struct { canid_t rx_id, tx_id; } tp; + + /* reserved for future CAN protocols address information */ + } can_addr; + }; + +To determine the interface index an appropriate ioctl() has to +be used (example for CAN_RAW sockets without error checking): + +.. code-block:: C + + int s; + struct sockaddr_can addr; + struct ifreq ifr; + + s = socket(PF_CAN, SOCK_RAW, CAN_RAW); + + strcpy(ifr.ifr_name, "can0" ); + ioctl(s, SIOCGIFINDEX, &ifr); + + addr.can_family = AF_CAN; + addr.can_ifindex = ifr.ifr_ifindex; + + bind(s, (struct sockaddr *)&addr, sizeof(addr)); + + (..) + +To bind a socket to all(!) CAN interfaces the interface index must +be 0 (zero). In this case the socket receives CAN frames from every +enabled CAN interface. To determine the originating CAN interface +the system call recvfrom(2) may be used instead of read(2). To send +on a socket that is bound to 'any' interface sendto(2) is needed to +specify the outgoing interface. + +Reading CAN frames from a bound CAN_RAW socket (see above) consists +of reading a struct can_frame: + +.. code-block:: C + + struct can_frame frame; + + nbytes = read(s, &frame, sizeof(struct can_frame)); + + if (nbytes < 0) { + perror("can raw socket read"); + return 1; + } + + /* paranoid check ... */ + if (nbytes < sizeof(struct can_frame)) { + fprintf(stderr, "read: incomplete CAN frame\n"); + return 1; + } + + /* do something with the received CAN frame */ + +Writing CAN frames can be done similarly, with the write(2) system call:: + + nbytes = write(s, &frame, sizeof(struct can_frame)); + +When the CAN interface is bound to 'any' existing CAN interface +(addr.can_ifindex = 0) it is recommended to use recvfrom(2) if the +information about the originating CAN interface is needed: + +.. code-block:: C + + struct sockaddr_can addr; + struct ifreq ifr; + socklen_t len = sizeof(addr); + struct can_frame frame; + + nbytes = recvfrom(s, &frame, sizeof(struct can_frame), + 0, (struct sockaddr*)&addr, &len); + + /* get interface name of the received CAN frame */ + ifr.ifr_ifindex = addr.can_ifindex; + ioctl(s, SIOCGIFNAME, &ifr); + printf("Received a CAN frame from interface %s", ifr.ifr_name); + +To write CAN frames on sockets bound to 'any' CAN interface the +outgoing interface has to be defined certainly: + +.. code-block:: C + + strcpy(ifr.ifr_name, "can0"); + ioctl(s, SIOCGIFINDEX, &ifr); + addr.can_ifindex = ifr.ifr_ifindex; + addr.can_family = AF_CAN; + + nbytes = sendto(s, &frame, sizeof(struct can_frame), + 0, (struct sockaddr*)&addr, sizeof(addr)); + +An accurate timestamp can be obtained with an ioctl(2) call after reading +a message from the socket: + +.. code-block:: C + + struct timeval tv; + ioctl(s, SIOCGSTAMP, &tv); + +The timestamp has a resolution of one microsecond and is set automatically +at the reception of a CAN frame. + +Remark about CAN FD (flexible data rate) support: + +Generally the handling of CAN FD is very similar to the formerly described +examples. The new CAN FD capable CAN controllers support two different +bitrates for the arbitration phase and the payload phase of the CAN FD frame +and up to 64 bytes of payload. This extended payload length breaks all the +kernel interfaces (ABI) which heavily rely on the CAN frame with fixed eight +bytes of payload (struct can_frame) like the CAN_RAW socket. Therefore e.g. +the CAN_RAW socket supports a new socket option CAN_RAW_FD_FRAMES that +switches the socket into a mode that allows the handling of CAN FD frames +and (legacy) CAN frames simultaneously (see :ref:`socketcan-rawfd`). + +The struct canfd_frame is defined in include/linux/can.h: + +.. code-block:: C + + struct canfd_frame { + canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */ + __u8 len; /* frame payload length in byte (0 .. 64) */ + __u8 flags; /* additional flags for CAN FD */ + __u8 __res0; /* reserved / padding */ + __u8 __res1; /* reserved / padding */ + __u8 data[64] __attribute__((aligned(8))); + }; + +The struct canfd_frame and the existing struct can_frame have the can_id, +the payload length and the payload data at the same offset inside their +structures. This allows to handle the different structures very similar. +When the content of a struct can_frame is copied into a struct canfd_frame +all structure elements can be used as-is - only the data[] becomes extended. + +When introducing the struct canfd_frame it turned out that the data length +code (DLC) of the struct can_frame was used as a length information as the +length and the DLC has a 1:1 mapping in the range of 0 .. 8. To preserve +the easy handling of the length information the canfd_frame.len element +contains a plain length value from 0 .. 64. So both canfd_frame.len and +can_frame.can_dlc are equal and contain a length information and no DLC. +For details about the distinction of CAN and CAN FD capable devices and +the mapping to the bus-relevant data length code (DLC), see :ref:`socketcan-can-fd-driver`. + +The length of the two CAN(FD) frame structures define the maximum transfer +unit (MTU) of the CAN(FD) network interface and skbuff data length. Two +definitions are specified for CAN specific MTUs in include/linux/can.h: + +.. code-block:: C + + #define CAN_MTU (sizeof(struct can_frame)) == 16 => 'legacy' CAN frame + #define CANFD_MTU (sizeof(struct canfd_frame)) == 72 => CAN FD frame + + +.. _socketcan-raw-sockets: + +RAW Protocol Sockets with can_filters (SOCK_RAW) +------------------------------------------------ + +Using CAN_RAW sockets is extensively comparable to the commonly +known access to CAN character devices. To meet the new possibilities +provided by the multi user SocketCAN approach, some reasonable +defaults are set at RAW socket binding time: + +- The filters are set to exactly one filter receiving everything +- The socket only receives valid data frames (=> no error message frames) +- The loopback of sent CAN frames is enabled (see :ref:`socketcan-local-loopback2`) +- The socket does not receive its own sent frames (in loopback mode) + +These default settings may be changed before or after binding the socket. +To use the referenced definitions of the socket options for CAN_RAW +sockets, include <linux/can/raw.h>. + + +.. _socketcan-rawfilter: + +RAW socket option CAN_RAW_FILTER +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The reception of CAN frames using CAN_RAW sockets can be controlled +by defining 0 .. n filters with the CAN_RAW_FILTER socket option. + +The CAN filter structure is defined in include/linux/can.h: + +.. code-block:: C + + struct can_filter { + canid_t can_id; + canid_t can_mask; + }; + +A filter matches, when: + +.. code-block:: C + + <received_can_id> & mask == can_id & mask + +which is analogous to known CAN controllers hardware filter semantics. +The filter can be inverted in this semantic, when the CAN_INV_FILTER +bit is set in can_id element of the can_filter structure. In +contrast to CAN controller hardware filters the user may set 0 .. n +receive filters for each open socket separately: + +.. code-block:: C + + struct can_filter rfilter[2]; + + rfilter[0].can_id = 0x123; + rfilter[0].can_mask = CAN_SFF_MASK; + rfilter[1].can_id = 0x200; + rfilter[1].can_mask = 0x700; + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter)); + +To disable the reception of CAN frames on the selected CAN_RAW socket: + +.. code-block:: C + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0); + +To set the filters to zero filters is quite obsolete as to not read +data causes the raw socket to discard the received CAN frames. But +having this 'send only' use-case we may remove the receive list in the +Kernel to save a little (really a very little!) CPU usage. + +CAN Filter Usage Optimisation +............................. + +The CAN filters are processed in per-device filter lists at CAN frame +reception time. To reduce the number of checks that need to be performed +while walking through the filter lists the CAN core provides an optimized +filter handling when the filter subscription focusses on a single CAN ID. + +For the possible 2048 SFF CAN identifiers the identifier is used as an index +to access the corresponding subscription list without any further checks. +For the 2^29 possible EFF CAN identifiers a 10 bit XOR folding is used as +hash function to retrieve the EFF table index. + +To benefit from the optimized filters for single CAN identifiers the +CAN_SFF_MASK or CAN_EFF_MASK have to be set into can_filter.mask together +with set CAN_EFF_FLAG and CAN_RTR_FLAG bits. A set CAN_EFF_FLAG bit in the +can_filter.mask makes clear that it matters whether a SFF or EFF CAN ID is +subscribed. E.g. in the example from above: + +.. code-block:: C + + rfilter[0].can_id = 0x123; + rfilter[0].can_mask = CAN_SFF_MASK; + +both SFF frames with CAN ID 0x123 and EFF frames with 0xXXXXX123 can pass. + +To filter for only 0x123 (SFF) and 0x12345678 (EFF) CAN identifiers the +filter has to be defined in this way to benefit from the optimized filters: + +.. code-block:: C + + struct can_filter rfilter[2]; + + rfilter[0].can_id = 0x123; + rfilter[0].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_SFF_MASK); + rfilter[1].can_id = 0x12345678 | CAN_EFF_FLAG; + rfilter[1].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_EFF_MASK); + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter)); + + +RAW Socket Option CAN_RAW_ERR_FILTER +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +As described in :ref:`socketcan-network-problem-notifications` the CAN interface driver can generate so +called Error Message Frames that can optionally be passed to the user +application in the same way as other CAN frames. The possible +errors are divided into different error classes that may be filtered +using the appropriate error mask. To register for every possible +error condition CAN_ERR_MASK can be used as value for the error mask. +The values for the error mask are defined in linux/can/error.h: + +.. code-block:: C + + can_err_mask_t err_mask = ( CAN_ERR_TX_TIMEOUT | CAN_ERR_BUSOFF ); + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER, + &err_mask, sizeof(err_mask)); + + +RAW Socket Option CAN_RAW_LOOPBACK +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To meet multi user needs the local loopback is enabled by default +(see :ref:`socketcan-local-loopback1` for details). But in some embedded use-cases +(e.g. when only one application uses the CAN bus) this loopback +functionality can be disabled (separately for each socket): + +.. code-block:: C + + int loopback = 0; /* 0 = disabled, 1 = enabled (default) */ + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_LOOPBACK, &loopback, sizeof(loopback)); + + +RAW socket option CAN_RAW_RECV_OWN_MSGS +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When the local loopback is enabled, all the sent CAN frames are +looped back to the open CAN sockets that registered for the CAN +frames' CAN-ID on this given interface to meet the multi user +needs. The reception of the CAN frames on the same socket that was +sending the CAN frame is assumed to be unwanted and therefore +disabled by default. This default behaviour may be changed on +demand: + +.. code-block:: C + + int recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */ + + setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS, + &recv_own_msgs, sizeof(recv_own_msgs)); + + +.. _socketcan-rawfd: + +RAW Socket Option CAN_RAW_FD_FRAMES +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +CAN FD support in CAN_RAW sockets can be enabled with a new socket option +CAN_RAW_FD_FRAMES which is off by default. When the new socket option is +not supported by the CAN_RAW socket (e.g. on older kernels), switching the +CAN_RAW_FD_FRAMES option returns the error -ENOPROTOOPT. + +Once CAN_RAW_FD_FRAMES is enabled the application can send both CAN frames +and CAN FD frames. OTOH the application has to handle CAN and CAN FD frames +when reading from the socket: + +.. code-block:: C + + CAN_RAW_FD_FRAMES enabled: CAN_MTU and CANFD_MTU are allowed + CAN_RAW_FD_FRAMES disabled: only CAN_MTU is allowed (default) + +Example: + +.. code-block:: C + + [ remember: CANFD_MTU == sizeof(struct canfd_frame) ] + + struct canfd_frame cfd; + + nbytes = read(s, &cfd, CANFD_MTU); + + if (nbytes == CANFD_MTU) { + printf("got CAN FD frame with length %d\n", cfd.len); + /* cfd.flags contains valid data */ + } else if (nbytes == CAN_MTU) { + printf("got legacy CAN frame with length %d\n", cfd.len); + /* cfd.flags is undefined */ + } else { + fprintf(stderr, "read: invalid CAN(FD) frame\n"); + return 1; + } + + /* the content can be handled independently from the received MTU size */ + + printf("can_id: %X data length: %d data: ", cfd.can_id, cfd.len); + for (i = 0; i < cfd.len; i++) + printf("%02X ", cfd.data[i]); + +When reading with size CANFD_MTU only returns CAN_MTU bytes that have +been received from the socket a legacy CAN frame has been read into the +provided CAN FD structure. Note that the canfd_frame.flags data field is +not specified in the struct can_frame and therefore it is only valid in +CANFD_MTU sized CAN FD frames. + +Implementation hint for new CAN applications: + +To build a CAN FD aware application use struct canfd_frame as basic CAN +data structure for CAN_RAW based applications. When the application is +executed on an older Linux kernel and switching the CAN_RAW_FD_FRAMES +socket option returns an error: No problem. You'll get legacy CAN frames +or CAN FD frames and can process them the same way. + +When sending to CAN devices make sure that the device is capable to handle +CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU. +The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. + + +RAW socket option CAN_RAW_JOIN_FILTERS +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The CAN_RAW socket can set multiple CAN identifier specific filters that +lead to multiple filters in the af_can.c filter processing. These filters +are indenpendent from each other which leads to logical OR'ed filters when +applied (see :ref:`socketcan-rawfilter`). + +This socket option joines the given CAN filters in the way that only CAN +frames are passed to user space that matched *all* given CAN filters. The +semantic for the applied filters is therefore changed to a logical AND. + +This is useful especially when the filterset is a combination of filters +where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or +CAN ID ranges from the incoming traffic. + + +RAW Socket Returned Message Flags +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When using recvmsg() call, the msg->msg_flags may contain following flags: + +MSG_DONTROUTE: + set when the received frame was created on the local host. + +MSG_CONFIRM: + set when the frame was sent via the socket it is received on. + This flag can be interpreted as a 'transmission confirmation' when the + CAN driver supports the echo of frames on driver level, see + :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`. + In order to receive such messages, CAN_RAW_RECV_OWN_MSGS must be set. + + +Broadcast Manager Protocol Sockets (SOCK_DGRAM) +----------------------------------------------- + +The Broadcast Manager protocol provides a command based configuration +interface to filter and send (e.g. cyclic) CAN messages in kernel space. + +Receive filters can be used to down sample frequent messages; detect events +such as message contents changes, packet length changes, and do time-out +monitoring of received messages. + +Periodic transmission tasks of CAN frames or a sequence of CAN frames can be +created and modified at runtime; both the message content and the two +possible transmit intervals can be altered. + +A BCM socket is not intended for sending individual CAN frames using the +struct can_frame as known from the CAN_RAW socket. Instead a special BCM +configuration message is defined. The basic BCM configuration message used +to communicate with the broadcast manager and the available operations are +defined in the linux/can/bcm.h include. The BCM message consists of a +message header with a command ('opcode') followed by zero or more CAN frames. +The broadcast manager sends responses to user space in the same form: + +.. code-block:: C + + struct bcm_msg_head { + __u32 opcode; /* command */ + __u32 flags; /* special flags */ + __u32 count; /* run 'count' times with ival1 */ + struct timeval ival1, ival2; /* count and subsequent interval */ + canid_t can_id; /* unique can_id for task */ + __u32 nframes; /* number of can_frames following */ + struct can_frame frames[0]; + }; + +The aligned payload 'frames' uses the same basic CAN frame structure defined +at the beginning of :ref:`socketcan-rawfd` and in the include/linux/can.h include. All +messages to the broadcast manager from user space have this structure. + +Note a CAN_BCM socket must be connected instead of bound after socket +creation (example without error checking): + +.. code-block:: C + + int s; + struct sockaddr_can addr; + struct ifreq ifr; + + s = socket(PF_CAN, SOCK_DGRAM, CAN_BCM); + + strcpy(ifr.ifr_name, "can0"); + ioctl(s, SIOCGIFINDEX, &ifr); + + addr.can_family = AF_CAN; + addr.can_ifindex = ifr.ifr_ifindex; + + connect(s, (struct sockaddr *)&addr, sizeof(addr)); + + (..) + +The broadcast manager socket is able to handle any number of in flight +transmissions or receive filters concurrently. The different RX/TX jobs are +distinguished by the unique can_id in each BCM message. However additional +CAN_BCM sockets are recommended to communicate on multiple CAN interfaces. +When the broadcast manager socket is bound to 'any' CAN interface (=> the +interface index is set to zero) the configured receive filters apply to any +CAN interface unless the sendto() syscall is used to overrule the 'any' CAN +interface index. When using recvfrom() instead of read() to retrieve BCM +socket messages the originating CAN interface is provided in can_ifindex. + + +Broadcast Manager Operations +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The opcode defines the operation for the broadcast manager to carry out, +or details the broadcast managers response to several events, including +user requests. + +Transmit Operations (user space to broadcast manager): + +TX_SETUP: + Create (cyclic) transmission task. + +TX_DELETE: + Remove (cyclic) transmission task, requires only can_id. + +TX_READ: + Read properties of (cyclic) transmission task for can_id. + +TX_SEND: + Send one CAN frame. + +Transmit Responses (broadcast manager to user space): + +TX_STATUS: + Reply to TX_READ request (transmission task configuration). + +TX_EXPIRED: + Notification when counter finishes sending at initial interval + 'ival1'. Requires the TX_COUNTEVT flag to be set at TX_SETUP. + +Receive Operations (user space to broadcast manager): + +RX_SETUP: + Create RX content filter subscription. + +RX_DELETE: + Remove RX content filter subscription, requires only can_id. + +RX_READ: + Read properties of RX content filter subscription for can_id. + +Receive Responses (broadcast manager to user space): + +RX_STATUS: + Reply to RX_READ request (filter task configuration). + +RX_TIMEOUT: + Cyclic message is detected to be absent (timer ival1 expired). + +RX_CHANGED: + BCM message with updated CAN frame (detected content change). + Sent on first message received or on receipt of revised CAN messages. + + +Broadcast Manager Message Flags +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When sending a message to the broadcast manager the 'flags' element may +contain the following flag definitions which influence the behaviour: + +SETTIMER: + Set the values of ival1, ival2 and count + +STARTTIMER: + Start the timer with the actual values of ival1, ival2 + and count. Starting the timer leads simultaneously to emit a CAN frame. + +TX_COUNTEVT: + Create the message TX_EXPIRED when count expires + +TX_ANNOUNCE: + A change of data by the process is emitted immediately. + +TX_CP_CAN_ID: + Copies the can_id from the message header to each + subsequent frame in frames. This is intended as usage simplification. For + TX tasks the unique can_id from the message header may differ from the + can_id(s) stored for transmission in the subsequent struct can_frame(s). + +RX_FILTER_ID: + Filter by can_id alone, no frames required (nframes=0). + +RX_CHECK_DLC: + A change of the DLC leads to an RX_CHANGED. + +RX_NO_AUTOTIMER: + Prevent automatically starting the timeout monitor. + +RX_ANNOUNCE_RESUME: + If passed at RX_SETUP and a receive timeout occurred, a + RX_CHANGED message will be generated when the (cyclic) receive restarts. + +TX_RESET_MULTI_IDX: + Reset the index for the multiple frame transmission. + +RX_RTR_FRAME: + Send reply for RTR-request (placed in op->frames[0]). + + +Broadcast Manager Transmission Timers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Periodic transmission configurations may use up to two interval timers. +In this case the BCM sends a number of messages ('count') at an interval +'ival1', then continuing to send at another given interval 'ival2'. When +only one timer is needed 'count' is set to zero and only 'ival2' is used. +When SET_TIMER and START_TIMER flag were set the timers are activated. +The timer values can be altered at runtime when only SET_TIMER is set. + + +Broadcast Manager message sequence transmission +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Up to 256 CAN frames can be transmitted in a sequence in the case of a cyclic +TX task configuration. The number of CAN frames is provided in the 'nframes' +element of the BCM message head. The defined number of CAN frames are added +as array to the TX_SETUP BCM configuration message: + +.. code-block:: C + + /* create a struct to set up a sequence of four CAN frames */ + struct { + struct bcm_msg_head msg_head; + struct can_frame frame[4]; + } mytxmsg; + + (..) + mytxmsg.msg_head.nframes = 4; + (..) + + write(s, &mytxmsg, sizeof(mytxmsg)); + +With every transmission the index in the array of CAN frames is increased +and set to zero at index overflow. + + +Broadcast Manager Receive Filter Timers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The timer values ival1 or ival2 may be set to non-zero values at RX_SETUP. +When the SET_TIMER flag is set the timers are enabled: + +ival1: + Send RX_TIMEOUT when a received message is not received again within + the given time. When START_TIMER is set at RX_SETUP the timeout detection + is activated directly - even without a former CAN frame reception. + +ival2: + Throttle the received message rate down to the value of ival2. This + is useful to reduce messages for the application when the signal inside the + CAN frame is stateless as state changes within the ival2 periode may get + lost. + +Broadcast Manager Multiplex Message Receive Filter +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To filter for content changes in multiplex message sequences an array of more +than one CAN frames can be passed in a RX_SETUP configuration message. The +data bytes of the first CAN frame contain the mask of relevant bits that +have to match in the subsequent CAN frames with the received CAN frame. +If one of the subsequent CAN frames is matching the bits in that frame data +mark the relevant content to be compared with the previous received content. +Up to 257 CAN frames (multiplex filter bit mask CAN frame plus 256 CAN +filters) can be added as array to the TX_SETUP BCM configuration message: + +.. code-block:: C + + /* usually used to clear CAN frame data[] - beware of endian problems! */ + #define U64_DATA(p) (*(unsigned long long*)(p)->data) + + struct { + struct bcm_msg_head msg_head; + struct can_frame frame[5]; + } msg; + + msg.msg_head.opcode = RX_SETUP; + msg.msg_head.can_id = 0x42; + msg.msg_head.flags = 0; + msg.msg_head.nframes = 5; + U64_DATA(&msg.frame[0]) = 0xFF00000000000000ULL; /* MUX mask */ + U64_DATA(&msg.frame[1]) = 0x01000000000000FFULL; /* data mask (MUX 0x01) */ + U64_DATA(&msg.frame[2]) = 0x0200FFFF000000FFULL; /* data mask (MUX 0x02) */ + U64_DATA(&msg.frame[3]) = 0x330000FFFFFF0003ULL; /* data mask (MUX 0x33) */ + U64_DATA(&msg.frame[4]) = 0x4F07FC0FF0000000ULL; /* data mask (MUX 0x4F) */ + + write(s, &msg, sizeof(msg)); + + +Broadcast Manager CAN FD Support +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The programming API of the CAN_BCM depends on struct can_frame which is +given as array directly behind the bcm_msg_head structure. To follow this +schema for the CAN FD frames a new flag 'CAN_FD_FRAME' in the bcm_msg_head +flags indicates that the concatenated CAN frame structures behind the +bcm_msg_head are defined as struct canfd_frame: + +.. code-block:: C + + struct { + struct bcm_msg_head msg_head; + struct canfd_frame frame[5]; + } msg; + + msg.msg_head.opcode = RX_SETUP; + msg.msg_head.can_id = 0x42; + msg.msg_head.flags = CAN_FD_FRAME; + msg.msg_head.nframes = 5; + (..) + +When using CAN FD frames for multiplex filtering the MUX mask is still +expected in the first 64 bit of the struct canfd_frame data section. + + +Connected Transport Protocols (SOCK_SEQPACKET) +---------------------------------------------- + +(to be written) + + +Unconnected Transport Protocols (SOCK_DGRAM) +-------------------------------------------- + +(to be written) + + +.. _socketcan-core-module: + +SocketCAN Core Module +===================== + +The SocketCAN core module implements the protocol family +PF_CAN. CAN protocol modules are loaded by the core module at +runtime. The core module provides an interface for CAN protocol +modules to subscribe needed CAN IDs (see :ref:`socketcan-receive-lists`). + + +can.ko Module Params +-------------------- + +- **stats_timer**: + To calculate the SocketCAN core statistics + (e.g. current/maximum frames per second) this 1 second timer is + invoked at can.ko module start time by default. This timer can be + disabled by using stattimer=0 on the module commandline. + +- **debug**: + (removed since SocketCAN SVN r546) + + +procfs content +-------------- + +As described in :ref:`socketcan-receive-lists` the SocketCAN core uses several filter +lists to deliver received CAN frames to CAN protocol modules. These +receive lists, their filters and the count of filter matches can be +checked in the appropriate receive list. All entries contain the +device and a protocol module identifier:: + + foo@bar:~$ cat /proc/net/can/rcvlist_all + + receive list 'rx_all': + (vcan3: no entry) + (vcan2: no entry) + (vcan1: no entry) + device can_id can_mask function userdata matches ident + vcan0 000 00000000 f88e6370 f6c6f400 0 raw + (any: no entry) + +In this example an application requests any CAN traffic from vcan0:: + + rcvlist_all - list for unfiltered entries (no filter operations) + rcvlist_eff - list for single extended frame (EFF) entries + rcvlist_err - list for error message frames masks + rcvlist_fil - list for mask/value filters + rcvlist_inv - list for mask/value filters (inverse semantic) + rcvlist_sff - list for single standard frame (SFF) entries + +Additional procfs files in /proc/net/can:: + + stats - SocketCAN core statistics (rx/tx frames, match ratios, ...) + reset_stats - manual statistic reset + version - prints the SocketCAN core version and the ABI version + + +Writing Own CAN Protocol Modules +-------------------------------- + +To implement a new protocol in the protocol family PF_CAN a new +protocol has to be defined in include/linux/can.h . +The prototypes and definitions to use the SocketCAN core can be +accessed by including include/linux/can/core.h . +In addition to functions that register the CAN protocol and the +CAN device notifier chain there are functions to subscribe CAN +frames received by CAN interfaces and to send CAN frames:: + + can_rx_register - subscribe CAN frames from a specific interface + can_rx_unregister - unsubscribe CAN frames from a specific interface + can_send - transmit a CAN frame (optional with local loopback) + +For details see the kerneldoc documentation in net/can/af_can.c or +the source code of net/can/raw.c or net/can/bcm.c . + + +CAN Network Drivers +=================== + +Writing a CAN network device driver is much easier than writing a +CAN character device driver. Similar to other known network device +drivers you mainly have to deal with: + +- TX: Put the CAN frame from the socket buffer to the CAN controller. +- RX: Put the CAN frame from the CAN controller to the socket buffer. + +See e.g. at Documentation/networking/netdevices.txt . The differences +for writing CAN network device driver are described below: + + +General Settings +---------------- + +.. code-block:: C + + dev->type = ARPHRD_CAN; /* the netdevice hardware type */ + dev->flags = IFF_NOARP; /* CAN has no arp */ + + dev->mtu = CAN_MTU; /* sizeof(struct can_frame) -> legacy CAN interface */ + + or alternative, when the controller supports CAN with flexible data rate: + dev->mtu = CANFD_MTU; /* sizeof(struct canfd_frame) -> CAN FD interface */ + +The struct can_frame or struct canfd_frame is the payload of each socket +buffer (skbuff) in the protocol family PF_CAN. + + +.. _socketcan-local-loopback2: + +Local Loopback of Sent Frames +----------------------------- + +As described in :ref:`socketcan-local-loopback1` the CAN network device driver should +support a local loopback functionality similar to the local echo +e.g. of tty devices. In this case the driver flag IFF_ECHO has to be +set to prevent the PF_CAN core from locally echoing sent frames +(aka loopback) as fallback solution:: + + dev->flags = (IFF_NOARP | IFF_ECHO); + + +CAN Controller Hardware Filters +------------------------------- + +To reduce the interrupt load on deep embedded systems some CAN +controllers support the filtering of CAN IDs or ranges of CAN IDs. +These hardware filter capabilities vary from controller to +controller and have to be identified as not feasible in a multi-user +networking approach. The use of the very controller specific +hardware filters could make sense in a very dedicated use-case, as a +filter on driver level would affect all users in the multi-user +system. The high efficient filter sets inside the PF_CAN core allow +to set different multiple filters for each socket separately. +Therefore the use of hardware filters goes to the category 'handmade +tuning on deep embedded systems'. The author is running a MPC603e +@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus +load without any problems ... + + +The Virtual CAN Driver (vcan) +----------------------------- + +Similar to the network loopback devices, vcan offers a virtual local +CAN interface. A full qualified address on CAN consists of + +- a unique CAN Identifier (CAN ID) +- the CAN bus this CAN ID is transmitted on (e.g. can0) + +so in common use cases more than one virtual CAN interface is needed. + +The virtual CAN interfaces allow the transmission and reception of CAN +frames without real CAN controller hardware. Virtual CAN network +devices are usually named 'vcanX', like vcan0 vcan1 vcan2 ... +When compiled as a module the virtual CAN driver module is called vcan.ko + +Since Linux Kernel version 2.6.24 the vcan driver supports the Kernel +netlink interface to create vcan network devices. The creation and +removal of vcan network devices can be managed with the ip(8) tool:: + + - Create a virtual CAN network interface: + $ ip link add type vcan + + - Create a virtual CAN network interface with a specific name 'vcan42': + $ ip link add dev vcan42 type vcan + + - Remove a (virtual CAN) network interface 'vcan42': + $ ip link del vcan42 + + +The CAN Network Device Driver Interface +--------------------------------------- + +The CAN network device driver interface provides a generic interface +to setup, configure and monitor CAN network devices. The user can then +configure the CAN device, like setting the bit-timing parameters, via +the netlink interface using the program "ip" from the "IPROUTE2" +utility suite. The following chapter describes briefly how to use it. +Furthermore, the interface uses a common data structure and exports a +set of common functions, which all real CAN network device drivers +should use. Please have a look to the SJA1000 or MSCAN driver to +understand how to use them. The name of the module is can-dev.ko. + + +Netlink interface to set/get devices properties +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The CAN device must be configured via netlink interface. The supported +netlink message types are defined and briefly described in +"include/linux/can/netlink.h". CAN link support for the program "ip" +of the IPROUTE2 utility suite is available and it can be used as shown +below: + +Setting CAN device properties:: + + $ ip link set can0 type can help + Usage: ip link set DEVICE type can + [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] | + [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1 + phase-seg2 PHASE-SEG2 [ sjw SJW ] ] + + [ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] | + [ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1 + dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ] + + [ loopback { on | off } ] + [ listen-only { on | off } ] + [ triple-sampling { on | off } ] + [ one-shot { on | off } ] + [ berr-reporting { on | off } ] + [ fd { on | off } ] + [ fd-non-iso { on | off } ] + [ presume-ack { on | off } ] + + [ restart-ms TIME-MS ] + [ restart ] + + Where: BITRATE := { 1..1000000 } + SAMPLE-POINT := { 0.000..0.999 } + TQ := { NUMBER } + PROP-SEG := { 1..8 } + PHASE-SEG1 := { 1..8 } + PHASE-SEG2 := { 1..8 } + SJW := { 1..4 } + RESTART-MS := { 0 | NUMBER } + +Display CAN device details and statistics:: + + $ ip -details -statistics link show can0 + 2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP qlen 10 + link/can + can <TRIPLE-SAMPLING> state ERROR-ACTIVE restart-ms 100 + bitrate 125000 sample_point 0.875 + tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1 + sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 + clock 8000000 + re-started bus-errors arbit-lost error-warn error-pass bus-off + 41 17457 0 41 42 41 + RX: bytes packets errors dropped overrun mcast + 140859 17608 17457 0 0 0 + TX: bytes packets errors dropped carrier collsns + 861 112 0 41 0 0 + +More info to the above output: + +"<TRIPLE-SAMPLING>" + Shows the list of selected CAN controller modes: LOOPBACK, + LISTEN-ONLY, or TRIPLE-SAMPLING. + +"state ERROR-ACTIVE" + The current state of the CAN controller: "ERROR-ACTIVE", + "ERROR-WARNING", "ERROR-PASSIVE", "BUS-OFF" or "STOPPED" + +"restart-ms 100" + Automatic restart delay time. If set to a non-zero value, a + restart of the CAN controller will be triggered automatically + in case of a bus-off condition after the specified delay time + in milliseconds. By default it's off. + +"bitrate 125000 sample-point 0.875" + Shows the real bit-rate in bits/sec and the sample-point in the + range 0.000..0.999. If the calculation of bit-timing parameters + is enabled in the kernel (CONFIG_CAN_CALC_BITTIMING=y), the + bit-timing can be defined by setting the "bitrate" argument. + Optionally the "sample-point" can be specified. By default it's + 0.000 assuming CIA-recommended sample-points. + +"tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1" + Shows the time quanta in ns, propagation segment, phase buffer + segment 1 and 2 and the synchronisation jump width in units of + tq. They allow to define the CAN bit-timing in a hardware + independent format as proposed by the Bosch CAN 2.0 spec (see + chapter 8 of http://www.semiconductors.bosch.de/pdf/can2spec.pdf). + +"sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 clock 8000000" + Shows the bit-timing constants of the CAN controller, here the + "sja1000". The minimum and maximum values of the time segment 1 + and 2, the synchronisation jump width in units of tq, the + bitrate pre-scaler and the CAN system clock frequency in Hz. + These constants could be used for user-defined (non-standard) + bit-timing calculation algorithms in user-space. + +"re-started bus-errors arbit-lost error-warn error-pass bus-off" + Shows the number of restarts, bus and arbitration lost errors, + and the state changes to the error-warning, error-passive and + bus-off state. RX overrun errors are listed in the "overrun" + field of the standard network statistics. + +Setting the CAN Bit-Timing +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The CAN bit-timing parameters can always be defined in a hardware +independent format as proposed in the Bosch CAN 2.0 specification +specifying the arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" +and "sjw":: + + $ ip link set canX type can tq 125 prop-seg 6 \ + phase-seg1 7 phase-seg2 2 sjw 1 + +If the kernel option CONFIG_CAN_CALC_BITTIMING is enabled, CIA +recommended CAN bit-timing parameters will be calculated if the bit- +rate is specified with the argument "bitrate":: + + $ ip link set canX type can bitrate 125000 + +Note that this works fine for the most common CAN controllers with +standard bit-rates but may *fail* for exotic bit-rates or CAN system +clock frequencies. Disabling CONFIG_CAN_CALC_BITTIMING saves some +space and allows user-space tools to solely determine and set the +bit-timing parameters. The CAN controller specific bit-timing +constants can be used for that purpose. They are listed by the +following command:: + + $ ip -details link show can0 + ... + sja1000: clock 8000000 tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 + + +Starting and Stopping the CAN Network Device +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +A CAN network device is started or stopped as usual with the command +"ifconfig canX up/down" or "ip link set canX up/down". Be aware that +you *must* define proper bit-timing parameters for real CAN devices +before you can start it to avoid error-prone default settings:: + + $ ip link set canX up type can bitrate 125000 + +A device may enter the "bus-off" state if too many errors occurred on +the CAN bus. Then no more messages are received or sent. An automatic +bus-off recovery can be enabled by setting the "restart-ms" to a +non-zero value, e.g.:: + + $ ip link set canX type can restart-ms 100 + +Alternatively, the application may realize the "bus-off" condition +by monitoring CAN error message frames and do a restart when +appropriate with the command:: + + $ ip link set canX type can restart + +Note that a restart will also create a CAN error message frame (see +also :ref:`socketcan-network-problem-notifications`). + + +.. _socketcan-can-fd-driver: + +CAN FD (Flexible Data Rate) Driver Support +------------------------------------------ + +CAN FD capable CAN controllers support two different bitrates for the +arbitration phase and the payload phase of the CAN FD frame. Therefore a +second bit timing has to be specified in order to enable the CAN FD bitrate. + +Additionally CAN FD capable CAN controllers support up to 64 bytes of +payload. The representation of this length in can_frame.can_dlc and +canfd_frame.len for userspace applications and inside the Linux network +layer is a plain value from 0 .. 64 instead of the CAN 'data length code'. +The data length code was a 1:1 mapping to the payload length in the legacy +CAN frames anyway. The payload length to the bus-relevant DLC mapping is +only performed inside the CAN drivers, preferably with the helper +functions can_dlc2len() and can_len2dlc(). + +The CAN netdevice driver capabilities can be distinguished by the network +devices maximum transfer unit (MTU):: + + MTU = 16 (CAN_MTU) => sizeof(struct can_frame) => 'legacy' CAN device + MTU = 72 (CANFD_MTU) => sizeof(struct canfd_frame) => CAN FD capable device + +The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. +N.B. CAN FD capable devices can also handle and send legacy CAN frames. + +When configuring CAN FD capable CAN controllers an additional 'data' bitrate +has to be set. This bitrate for the data phase of the CAN FD frame has to be +at least the bitrate which was configured for the arbitration phase. This +second bitrate is specified analogue to the first bitrate but the bitrate +setting keywords for the 'data' bitrate start with 'd' e.g. dbitrate, +dsample-point, dsjw or dtq and similar settings. When a data bitrate is set +within the configuration process the controller option "fd on" can be +specified to enable the CAN FD mode in the CAN controller. This controller +option also switches the device MTU to 72 (CANFD_MTU). + +The first CAN FD specification presented as whitepaper at the International +CAN Conference 2012 needed to be improved for data integrity reasons. +Therefore two CAN FD implementations have to be distinguished today: + +- ISO compliant: The ISO 11898-1:2015 CAN FD implementation (default) +- non-ISO compliant: The CAN FD implementation following the 2012 whitepaper + +Finally there are three types of CAN FD controllers: + +1. ISO compliant (fixed) +2. non-ISO compliant (fixed, like the M_CAN IP core v3.0.1 in m_can.c) +3. ISO/non-ISO CAN FD controllers (switchable, like the PEAK PCAN-USB FD) + +The current ISO/non-ISO mode is announced by the CAN controller driver via +netlink and displayed by the 'ip' tool (controller option FD-NON-ISO). +The ISO/non-ISO-mode can be altered by setting 'fd-non-iso {on|off}' for +switchable CAN FD controllers only. + +Example configuring 500 kbit/s arbitration bitrate and 4 Mbit/s data bitrate:: + + $ ip link set can0 up type can bitrate 500000 sample-point 0.75 \ + dbitrate 4000000 dsample-point 0.8 fd on + $ ip -details link show can0 + 5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UNKNOWN \ + mode DEFAULT group default qlen 10 + link/can promiscuity 0 + can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 + bitrate 500000 sample-point 0.750 + tq 50 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1 + pcan_usb_pro_fd: tseg1 1..64 tseg2 1..16 sjw 1..16 brp 1..1024 \ + brp-inc 1 + dbitrate 4000000 dsample-point 0.800 + dtq 12 dprop-seg 7 dphase-seg1 8 dphase-seg2 4 dsjw 1 + pcan_usb_pro_fd: dtseg1 1..16 dtseg2 1..8 dsjw 1..4 dbrp 1..1024 \ + dbrp-inc 1 + clock 80000000 + +Example when 'fd-non-iso on' is added on this switchable CAN FD adapter:: + + can <FD,FD-NON-ISO> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 + + +Supported CAN Hardware +---------------------- + +Please check the "Kconfig" file in "drivers/net/can" to get an actual +list of the support CAN hardware. On the SocketCAN project website +(see :ref:`socketcan-resources`) there might be further drivers available, also for +older kernel versions. + + +.. _socketcan-resources: + +SocketCAN Resources +=================== + +The Linux CAN / SocketCAN project resources (project site / mailing list) +are referenced in the MAINTAINERS file in the Linux source tree. +Search for CAN NETWORK [LAYERS|DRIVERS]. + +Credits +======= + +- Oliver Hartkopp (PF_CAN core, filters, drivers, bcm, SJA1000 driver) +- Urs Thuermann (PF_CAN core, kernel integration, socket interfaces, raw, vcan) +- Jan Kizka (RT-SocketCAN core, Socket-API reconciliation) +- Wolfgang Grandegger (RT-SocketCAN core & drivers, Raw Socket-API reviews, CAN device driver interface, MSCAN driver) +- Robert Schwebel (design reviews, PTXdist integration) +- Marc Kleine-Budde (design reviews, Kernel 2.6 cleanups, drivers) +- Benedikt Spranger (reviews) +- Thomas Gleixner (LKML reviews, coding style, posting hints) +- Andrey Volkov (kernel subtree structure, ioctls, MSCAN driver) +- Matthias Brukner (first SJA1000 CAN netdevice implementation Q2/2003) +- Klaus Hitschler (PEAK driver integration) +- Uwe Koppe (CAN netdevices with PF_PACKET approach) +- Michael Schulze (driver layer loopback requirement, RT CAN drivers review) +- Pavel Pisa (Bit-timing calculation) +- Sascha Hauer (SJA1000 platform driver) +- Sebastian Haas (SJA1000 EMS PCI driver) +- Markus Plessing (SJA1000 EMS PCI driver) +- Per Dalen (SJA1000 Kvaser PCI driver) +- Sam Ravnborg (reviews, coding style, kbuild help) diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt deleted file mode 100644 index aa15b9e..0000000 --- a/Documentation/networking/can.txt +++ /dev/null @@ -1,1308 +0,0 @@ -============================================================================ - -can.txt - -Readme file for the Controller Area Network Protocol Family (aka SocketCAN) - -This file contains - - 1 Overview / What is SocketCAN - - 2 Motivation / Why using the socket API - - 3 SocketCAN concept - 3.1 receive lists - 3.2 local loopback of sent frames - 3.3 network problem notifications - - 4 How to use SocketCAN - 4.1 RAW protocol sockets with can_filters (SOCK_RAW) - 4.1.1 RAW socket option CAN_RAW_FILTER - 4.1.2 RAW socket option CAN_RAW_ERR_FILTER - 4.1.3 RAW socket option CAN_RAW_LOOPBACK - 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS - 4.1.5 RAW socket option CAN_RAW_FD_FRAMES - 4.1.6 RAW socket option CAN_RAW_JOIN_FILTERS - 4.1.7 RAW socket returned message flags - 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM) - 4.2.1 Broadcast Manager operations - 4.2.2 Broadcast Manager message flags - 4.2.3 Broadcast Manager transmission timers - 4.2.4 Broadcast Manager message sequence transmission - 4.2.5 Broadcast Manager receive filter timers - 4.2.6 Broadcast Manager multiplex message receive filter - 4.2.7 Broadcast Manager CAN FD support - 4.3 connected transport protocols (SOCK_SEQPACKET) - 4.4 unconnected transport protocols (SOCK_DGRAM) - - 5 SocketCAN core module - 5.1 can.ko module params - 5.2 procfs content - 5.3 writing own CAN protocol modules - - 6 CAN network drivers - 6.1 general settings - 6.2 local loopback of sent frames - 6.3 CAN controller hardware filters - 6.4 The virtual CAN driver (vcan) - 6.5 The CAN network device driver interface - 6.5.1 Netlink interface to set/get devices properties - 6.5.2 Setting the CAN bit-timing - 6.5.3 Starting and stopping the CAN network device - 6.6 CAN FD (flexible data rate) driver support - 6.7 supported CAN hardware - - 7 SocketCAN resources - - 8 Credits - -============================================================================ - -1. Overview / What is SocketCAN --------------------------------- - -The socketcan package is an implementation of CAN protocols -(Controller Area Network) for Linux. CAN is a networking technology -which has widespread use in automation, embedded devices, and -automotive fields. While there have been other CAN implementations -for Linux based on character devices, SocketCAN uses the Berkeley -socket API, the Linux network stack and implements the CAN device -drivers as network interfaces. The CAN socket API has been designed -as similar as possible to the TCP/IP protocols to allow programmers, -familiar with network programming, to easily learn how to use CAN -sockets. - -2. Motivation / Why using the socket API ----------------------------------------- - -There have been CAN implementations for Linux before SocketCAN so the -question arises, why we have started another project. Most existing -implementations come as a device driver for some CAN hardware, they -are based on character devices and provide comparatively little -functionality. Usually, there is only a hardware-specific device -driver which provides a character device interface to send and -receive raw CAN frames, directly to/from the controller hardware. -Queueing of frames and higher-level transport protocols like ISO-TP -have to be implemented in user space applications. Also, most -character-device implementations support only one single process to -open the device at a time, similar to a serial interface. Exchanging -the CAN controller requires employment of another device driver and -often the need for adaption of large parts of the application to the -new driver's API. - -SocketCAN was designed to overcome all of these limitations. A new -protocol family has been implemented which provides a socket interface -to user space applications and which builds upon the Linux network -layer, enabling use all of the provided queueing functionality. A device -driver for CAN controller hardware registers itself with the Linux -network layer as a network device, so that CAN frames from the -controller can be passed up to the network layer and on to the CAN -protocol family module and also vice-versa. Also, the protocol family -module provides an API for transport protocol modules to register, so -that any number of transport protocols can be loaded or unloaded -dynamically. In fact, the can core module alone does not provide any -protocol and cannot be used without loading at least one additional -protocol module. Multiple sockets can be opened at the same time, -on different or the same protocol module and they can listen/send -frames on different or the same CAN IDs. Several sockets listening on -the same interface for frames with the same CAN ID are all passed the -same received matching CAN frames. An application wishing to -communicate using a specific transport protocol, e.g. ISO-TP, just -selects that protocol when opening the socket, and then can read and -write application data byte streams, without having to deal with -CAN-IDs, frames, etc. - -Similar functionality visible from user-space could be provided by a -character device, too, but this would lead to a technically inelegant -solution for a couple of reasons: - -* Intricate usage. Instead of passing a protocol argument to - socket(2) and using bind(2) to select a CAN interface and CAN ID, an - application would have to do all these operations using ioctl(2)s. - -* Code duplication. A character device cannot make use of the Linux - network queueing code, so all that code would have to be duplicated - for CAN networking. - -* Abstraction. In most existing character-device implementations, the - hardware-specific device driver for a CAN controller directly - provides the character device for the application to work with. - This is at least very unusual in Unix systems for both, char and - block devices. For example you don't have a character device for a - certain UART of a serial interface, a certain sound chip in your - computer, a SCSI or IDE controller providing access to your hard - disk or tape streamer device. Instead, you have abstraction layers - which provide a unified character or block device interface to the - application on the one hand, and a interface for hardware-specific - device drivers on the other hand. These abstractions are provided - by subsystems like the tty layer, the audio subsystem or the SCSI - and IDE subsystems for the devices mentioned above. - - The easiest way to implement a CAN device driver is as a character - device without such a (complete) abstraction layer, as is done by most - existing drivers. The right way, however, would be to add such a - layer with all the functionality like registering for certain CAN - IDs, supporting several open file descriptors and (de)multiplexing - CAN frames between them, (sophisticated) queueing of CAN frames, and - providing an API for device drivers to register with. However, then - it would be no more difficult, or may be even easier, to use the - networking framework provided by the Linux kernel, and this is what - SocketCAN does. - - The use of the networking framework of the Linux kernel is just the - natural and most appropriate way to implement CAN for Linux. - -3. SocketCAN concept ---------------------- - - As described in chapter 2 it is the main goal of SocketCAN to - provide a socket interface to user space applications which builds - upon the Linux network layer. In contrast to the commonly known - TCP/IP and ethernet networking, the CAN bus is a broadcast-only(!) - medium that has no MAC-layer addressing like ethernet. The CAN-identifier - (can_id) is used for arbitration on the CAN-bus. Therefore the CAN-IDs - have to be chosen uniquely on the bus. When designing a CAN-ECU - network the CAN-IDs are mapped to be sent by a specific ECU. - For this reason a CAN-ID can be treated best as a kind of source address. - - 3.1 receive lists - - The network transparent access of multiple applications leads to the - problem that different applications may be interested in the same - CAN-IDs from the same CAN network interface. The SocketCAN core - module - which implements the protocol family CAN - provides several - high efficient receive lists for this reason. If e.g. a user space - application opens a CAN RAW socket, the raw protocol module itself - requests the (range of) CAN-IDs from the SocketCAN core that are - requested by the user. The subscription and unsubscription of - CAN-IDs can be done for specific CAN interfaces or for all(!) known - CAN interfaces with the can_rx_(un)register() functions provided to - CAN protocol modules by the SocketCAN core (see chapter 5). - To optimize the CPU usage at runtime the receive lists are split up - into several specific lists per device that match the requested - filter complexity for a given use-case. - - 3.2 local loopback of sent frames - - As known from other networking concepts the data exchanging - applications may run on the same or different nodes without any - change (except for the according addressing information): - - ___ ___ ___ _______ ___ - | _ | | _ | | _ | | _ _ | | _ | - ||A|| ||B|| ||C|| ||A| |B|| ||C|| - |___| |___| |___| |_______| |___| - | | | | | - -----------------(1)- CAN bus -(2)--------------- - - To ensure that application A receives the same information in the - example (2) as it would receive in example (1) there is need for - some kind of local loopback of the sent CAN frames on the appropriate - node. - - The Linux network devices (by default) just can handle the - transmission and reception of media dependent frames. Due to the - arbitration on the CAN bus the transmission of a low prio CAN-ID - may be delayed by the reception of a high prio CAN frame. To - reflect the correct* traffic on the node the loopback of the sent - data has to be performed right after a successful transmission. If - the CAN network interface is not capable of performing the loopback for - some reason the SocketCAN core can do this task as a fallback solution. - See chapter 6.2 for details (recommended). - - The loopback functionality is enabled by default to reflect standard - networking behaviour for CAN applications. Due to some requests from - the RT-SocketCAN group the loopback optionally may be disabled for each - separate socket. See sockopts from the CAN RAW sockets in chapter 4.1. - - * = you really like to have this when you're running analyser tools - like 'candump' or 'cansniffer' on the (same) node. - - 3.3 network problem notifications - - The use of the CAN bus may lead to several problems on the physical - and media access control layer. Detecting and logging of these lower - layer problems is a vital requirement for CAN users to identify - hardware issues on the physical transceiver layer as well as - arbitration problems and error frames caused by the different - ECUs. The occurrence of detected errors are important for diagnosis - and have to be logged together with the exact timestamp. For this - reason the CAN interface driver can generate so called Error Message - Frames that can optionally be passed to the user application in the - same way as other CAN frames. Whenever an error on the physical layer - or the MAC layer is detected (e.g. by the CAN controller) the driver - creates an appropriate error message frame. Error messages frames can - be requested by the user application using the common CAN filter - mechanisms. Inside this filter definition the (interested) type of - errors may be selected. The reception of error messages is disabled - by default. The format of the CAN error message frame is briefly - described in the Linux header file "include/uapi/linux/can/error.h". - -4. How to use SocketCAN ------------------------- - - Like TCP/IP, you first need to open a socket for communicating over a - CAN network. Since SocketCAN implements a new protocol family, you - need to pass PF_CAN as the first argument to the socket(2) system - call. Currently, there are two CAN protocols to choose from, the raw - socket protocol and the broadcast manager (BCM). So to open a socket, - you would write - - s = socket(PF_CAN, SOCK_RAW, CAN_RAW); - - and - - s = socket(PF_CAN, SOCK_DGRAM, CAN_BCM); - - respectively. After the successful creation of the socket, you would - normally use the bind(2) system call to bind the socket to a CAN - interface (which is different from TCP/IP due to different addressing - - see chapter 3). After binding (CAN_RAW) or connecting (CAN_BCM) - the socket, you can read(2) and write(2) from/to the socket or use - send(2), sendto(2), sendmsg(2) and the recv* counterpart operations - on the socket as usual. There are also CAN specific socket options - described below. - - The basic CAN frame structure and the sockaddr structure are defined - in include/linux/can.h: - - struct can_frame { - canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */ - __u8 can_dlc; /* frame payload length in byte (0 .. 8) */ - __u8 __pad; /* padding */ - __u8 __res0; /* reserved / padding */ - __u8 __res1; /* reserved / padding */ - __u8 data[8] __attribute__((aligned(8))); - }; - - The alignment of the (linear) payload data[] to a 64bit boundary - allows the user to define their own structs and unions to easily access - the CAN payload. There is no given byteorder on the CAN bus by - default. A read(2) system call on a CAN_RAW socket transfers a - struct can_frame to the user space. - - The sockaddr_can structure has an interface index like the - PF_PACKET socket, that also binds to a specific interface: - - struct sockaddr_can { - sa_family_t can_family; - int can_ifindex; - union { - /* transport protocol class address info (e.g. ISOTP) */ - struct { canid_t rx_id, tx_id; } tp; - - /* reserved for future CAN protocols address information */ - } can_addr; - }; - - To determine the interface index an appropriate ioctl() has to - be used (example for CAN_RAW sockets without error checking): - - int s; - struct sockaddr_can addr; - struct ifreq ifr; - - s = socket(PF_CAN, SOCK_RAW, CAN_RAW); - - strcpy(ifr.ifr_name, "can0" ); - ioctl(s, SIOCGIFINDEX, &ifr); - - addr.can_family = AF_CAN; - addr.can_ifindex = ifr.ifr_ifindex; - - bind(s, (struct sockaddr *)&addr, sizeof(addr)); - - (..) - - To bind a socket to all(!) CAN interfaces the interface index must - be 0 (zero). In this case the socket receives CAN frames from every - enabled CAN interface. To determine the originating CAN interface - the system call recvfrom(2) may be used instead of read(2). To send - on a socket that is bound to 'any' interface sendto(2) is needed to - specify the outgoing interface. - - Reading CAN frames from a bound CAN_RAW socket (see above) consists - of reading a struct can_frame: - - struct can_frame frame; - - nbytes = read(s, &frame, sizeof(struct can_frame)); - - if (nbytes < 0) { - perror("can raw socket read"); - return 1; - } - - /* paranoid check ... */ - if (nbytes < sizeof(struct can_frame)) { - fprintf(stderr, "read: incomplete CAN frame\n"); - return 1; - } - - /* do something with the received CAN frame */ - - Writing CAN frames can be done similarly, with the write(2) system call: - - nbytes = write(s, &frame, sizeof(struct can_frame)); - - When the CAN interface is bound to 'any' existing CAN interface - (addr.can_ifindex = 0) it is recommended to use recvfrom(2) if the - information about the originating CAN interface is needed: - - struct sockaddr_can addr; - struct ifreq ifr; - socklen_t len = sizeof(addr); - struct can_frame frame; - - nbytes = recvfrom(s, &frame, sizeof(struct can_frame), - 0, (struct sockaddr*)&addr, &len); - - /* get interface name of the received CAN frame */ - ifr.ifr_ifindex = addr.can_ifindex; - ioctl(s, SIOCGIFNAME, &ifr); - printf("Received a CAN frame from interface %s", ifr.ifr_name); - - To write CAN frames on sockets bound to 'any' CAN interface the - outgoing interface has to be defined certainly. - - strcpy(ifr.ifr_name, "can0"); - ioctl(s, SIOCGIFINDEX, &ifr); - addr.can_ifindex = ifr.ifr_ifindex; - addr.can_family = AF_CAN; - - nbytes = sendto(s, &frame, sizeof(struct can_frame), - 0, (struct sockaddr*)&addr, sizeof(addr)); - - An accurate timestamp can be obtained with an ioctl(2) call after reading - a message from the socket: - - struct timeval tv; - ioctl(s, SIOCGSTAMP, &tv); - - The timestamp has a resolution of one microsecond and is set automatically - at the reception of a CAN frame. - - Remark about CAN FD (flexible data rate) support: - - Generally the handling of CAN FD is very similar to the formerly described - examples. The new CAN FD capable CAN controllers support two different - bitrates for the arbitration phase and the payload phase of the CAN FD frame - and up to 64 bytes of payload. This extended payload length breaks all the - kernel interfaces (ABI) which heavily rely on the CAN frame with fixed eight - bytes of payload (struct can_frame) like the CAN_RAW socket. Therefore e.g. - the CAN_RAW socket supports a new socket option CAN_RAW_FD_FRAMES that - switches the socket into a mode that allows the handling of CAN FD frames - and (legacy) CAN frames simultaneously (see section 4.1.5). - - The struct canfd_frame is defined in include/linux/can.h: - - struct canfd_frame { - canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */ - __u8 len; /* frame payload length in byte (0 .. 64) */ - __u8 flags; /* additional flags for CAN FD */ - __u8 __res0; /* reserved / padding */ - __u8 __res1; /* reserved / padding */ - __u8 data[64] __attribute__((aligned(8))); - }; - - The struct canfd_frame and the existing struct can_frame have the can_id, - the payload length and the payload data at the same offset inside their - structures. This allows to handle the different structures very similar. - When the content of a struct can_frame is copied into a struct canfd_frame - all structure elements can be used as-is - only the data[] becomes extended. - - When introducing the struct canfd_frame it turned out that the data length - code (DLC) of the struct can_frame was used as a length information as the - length and the DLC has a 1:1 mapping in the range of 0 .. 8. To preserve - the easy handling of the length information the canfd_frame.len element - contains a plain length value from 0 .. 64. So both canfd_frame.len and - can_frame.can_dlc are equal and contain a length information and no DLC. - For details about the distinction of CAN and CAN FD capable devices and - the mapping to the bus-relevant data length code (DLC), see chapter 6.6. - - The length of the two CAN(FD) frame structures define the maximum transfer - unit (MTU) of the CAN(FD) network interface and skbuff data length. Two - definitions are specified for CAN specific MTUs in include/linux/can.h : - - #define CAN_MTU (sizeof(struct can_frame)) == 16 => 'legacy' CAN frame - #define CANFD_MTU (sizeof(struct canfd_frame)) == 72 => CAN FD frame - - 4.1 RAW protocol sockets with can_filters (SOCK_RAW) - - Using CAN_RAW sockets is extensively comparable to the commonly - known access to CAN character devices. To meet the new possibilities - provided by the multi user SocketCAN approach, some reasonable - defaults are set at RAW socket binding time: - - - The filters are set to exactly one filter receiving everything - - The socket only receives valid data frames (=> no error message frames) - - The loopback of sent CAN frames is enabled (see chapter 3.2) - - The socket does not receive its own sent frames (in loopback mode) - - These default settings may be changed before or after binding the socket. - To use the referenced definitions of the socket options for CAN_RAW - sockets, include <linux/can/raw.h>. - - 4.1.1 RAW socket option CAN_RAW_FILTER - - The reception of CAN frames using CAN_RAW sockets can be controlled - by defining 0 .. n filters with the CAN_RAW_FILTER socket option. - - The CAN filter structure is defined in include/linux/can.h: - - struct can_filter { - canid_t can_id; - canid_t can_mask; - }; - - A filter matches, when - - <received_can_id> & mask == can_id & mask - - which is analogous to known CAN controllers hardware filter semantics. - The filter can be inverted in this semantic, when the CAN_INV_FILTER - bit is set in can_id element of the can_filter structure. In - contrast to CAN controller hardware filters the user may set 0 .. n - receive filters for each open socket separately: - - struct can_filter rfilter[2]; - - rfilter[0].can_id = 0x123; - rfilter[0].can_mask = CAN_SFF_MASK; - rfilter[1].can_id = 0x200; - rfilter[1].can_mask = 0x700; - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter)); - - To disable the reception of CAN frames on the selected CAN_RAW socket: - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0); - - To set the filters to zero filters is quite obsolete as to not read - data causes the raw socket to discard the received CAN frames. But - having this 'send only' use-case we may remove the receive list in the - Kernel to save a little (really a very little!) CPU usage. - - 4.1.1.1 CAN filter usage optimisation - - The CAN filters are processed in per-device filter lists at CAN frame - reception time. To reduce the number of checks that need to be performed - while walking through the filter lists the CAN core provides an optimized - filter handling when the filter subscription focusses on a single CAN ID. - - For the possible 2048 SFF CAN identifiers the identifier is used as an index - to access the corresponding subscription list without any further checks. - For the 2^29 possible EFF CAN identifiers a 10 bit XOR folding is used as - hash function to retrieve the EFF table index. - - To benefit from the optimized filters for single CAN identifiers the - CAN_SFF_MASK or CAN_EFF_MASK have to be set into can_filter.mask together - with set CAN_EFF_FLAG and CAN_RTR_FLAG bits. A set CAN_EFF_FLAG bit in the - can_filter.mask makes clear that it matters whether a SFF or EFF CAN ID is - subscribed. E.g. in the example from above - - rfilter[0].can_id = 0x123; - rfilter[0].can_mask = CAN_SFF_MASK; - - both SFF frames with CAN ID 0x123 and EFF frames with 0xXXXXX123 can pass. - - To filter for only 0x123 (SFF) and 0x12345678 (EFF) CAN identifiers the - filter has to be defined in this way to benefit from the optimized filters: - - struct can_filter rfilter[2]; - - rfilter[0].can_id = 0x123; - rfilter[0].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_SFF_MASK); - rfilter[1].can_id = 0x12345678 | CAN_EFF_FLAG; - rfilter[1].can_mask = (CAN_EFF_FLAG | CAN_RTR_FLAG | CAN_EFF_MASK); - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter)); - - 4.1.2 RAW socket option CAN_RAW_ERR_FILTER - - As described in chapter 3.3 the CAN interface driver can generate so - called Error Message Frames that can optionally be passed to the user - application in the same way as other CAN frames. The possible - errors are divided into different error classes that may be filtered - using the appropriate error mask. To register for every possible - error condition CAN_ERR_MASK can be used as value for the error mask. - The values for the error mask are defined in linux/can/error.h . - - can_err_mask_t err_mask = ( CAN_ERR_TX_TIMEOUT | CAN_ERR_BUSOFF ); - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER, - &err_mask, sizeof(err_mask)); - - 4.1.3 RAW socket option CAN_RAW_LOOPBACK - - To meet multi user needs the local loopback is enabled by default - (see chapter 3.2 for details). But in some embedded use-cases - (e.g. when only one application uses the CAN bus) this loopback - functionality can be disabled (separately for each socket): - - int loopback = 0; /* 0 = disabled, 1 = enabled (default) */ - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_LOOPBACK, &loopback, sizeof(loopback)); - - 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS - - When the local loopback is enabled, all the sent CAN frames are - looped back to the open CAN sockets that registered for the CAN - frames' CAN-ID on this given interface to meet the multi user - needs. The reception of the CAN frames on the same socket that was - sending the CAN frame is assumed to be unwanted and therefore - disabled by default. This default behaviour may be changed on - demand: - - int recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */ - - setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS, - &recv_own_msgs, sizeof(recv_own_msgs)); - - 4.1.5 RAW socket option CAN_RAW_FD_FRAMES - - CAN FD support in CAN_RAW sockets can be enabled with a new socket option - CAN_RAW_FD_FRAMES which is off by default. When the new socket option is - not supported by the CAN_RAW socket (e.g. on older kernels), switching the - CAN_RAW_FD_FRAMES option returns the error -ENOPROTOOPT. - - Once CAN_RAW_FD_FRAMES is enabled the application can send both CAN frames - and CAN FD frames. OTOH the application has to handle CAN and CAN FD frames - when reading from the socket. - - CAN_RAW_FD_FRAMES enabled: CAN_MTU and CANFD_MTU are allowed - CAN_RAW_FD_FRAMES disabled: only CAN_MTU is allowed (default) - - Example: - [ remember: CANFD_MTU == sizeof(struct canfd_frame) ] - - struct canfd_frame cfd; - - nbytes = read(s, &cfd, CANFD_MTU); - - if (nbytes == CANFD_MTU) { - printf("got CAN FD frame with length %d\n", cfd.len); - /* cfd.flags contains valid data */ - } else if (nbytes == CAN_MTU) { - printf("got legacy CAN frame with length %d\n", cfd.len); - /* cfd.flags is undefined */ - } else { - fprintf(stderr, "read: invalid CAN(FD) frame\n"); - return 1; - } - - /* the content can be handled independently from the received MTU size */ - - printf("can_id: %X data length: %d data: ", cfd.can_id, cfd.len); - for (i = 0; i < cfd.len; i++) - printf("%02X ", cfd.data[i]); - - When reading with size CANFD_MTU only returns CAN_MTU bytes that have - been received from the socket a legacy CAN frame has been read into the - provided CAN FD structure. Note that the canfd_frame.flags data field is - not specified in the struct can_frame and therefore it is only valid in - CANFD_MTU sized CAN FD frames. - - Implementation hint for new CAN applications: - - To build a CAN FD aware application use struct canfd_frame as basic CAN - data structure for CAN_RAW based applications. When the application is - executed on an older Linux kernel and switching the CAN_RAW_FD_FRAMES - socket option returns an error: No problem. You'll get legacy CAN frames - or CAN FD frames and can process them the same way. - - When sending to CAN devices make sure that the device is capable to handle - CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU. - The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. - - 4.1.6 RAW socket option CAN_RAW_JOIN_FILTERS - - The CAN_RAW socket can set multiple CAN identifier specific filters that - lead to multiple filters in the af_can.c filter processing. These filters - are indenpendent from each other which leads to logical OR'ed filters when - applied (see 4.1.1). - - This socket option joines the given CAN filters in the way that only CAN - frames are passed to user space that matched *all* given CAN filters. The - semantic for the applied filters is therefore changed to a logical AND. - - This is useful especially when the filterset is a combination of filters - where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or - CAN ID ranges from the incoming traffic. - - 4.1.7 RAW socket returned message flags - - When using recvmsg() call, the msg->msg_flags may contain following flags: - - MSG_DONTROUTE: set when the received frame was created on the local host. - - MSG_CONFIRM: set when the frame was sent via the socket it is received on. - This flag can be interpreted as a 'transmission confirmation' when the - CAN driver supports the echo of frames on driver level, see 3.2 and 6.2. - In order to receive such messages, CAN_RAW_RECV_OWN_MSGS must be set. - - 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM) - - The Broadcast Manager protocol provides a command based configuration - interface to filter and send (e.g. cyclic) CAN messages in kernel space. - - Receive filters can be used to down sample frequent messages; detect events - such as message contents changes, packet length changes, and do time-out - monitoring of received messages. - - Periodic transmission tasks of CAN frames or a sequence of CAN frames can be - created and modified at runtime; both the message content and the two - possible transmit intervals can be altered. - - A BCM socket is not intended for sending individual CAN frames using the - struct can_frame as known from the CAN_RAW socket. Instead a special BCM - configuration message is defined. The basic BCM configuration message used - to communicate with the broadcast manager and the available operations are - defined in the linux/can/bcm.h include. The BCM message consists of a - message header with a command ('opcode') followed by zero or more CAN frames. - The broadcast manager sends responses to user space in the same form: - - struct bcm_msg_head { - __u32 opcode; /* command */ - __u32 flags; /* special flags */ - __u32 count; /* run 'count' times with ival1 */ - struct timeval ival1, ival2; /* count and subsequent interval */ - canid_t can_id; /* unique can_id for task */ - __u32 nframes; /* number of can_frames following */ - struct can_frame frames[0]; - }; - - The aligned payload 'frames' uses the same basic CAN frame structure defined - at the beginning of section 4 and in the include/linux/can.h include. All - messages to the broadcast manager from user space have this structure. - - Note a CAN_BCM socket must be connected instead of bound after socket - creation (example without error checking): - - int s; - struct sockaddr_can addr; - struct ifreq ifr; - - s = socket(PF_CAN, SOCK_DGRAM, CAN_BCM); - - strcpy(ifr.ifr_name, "can0"); - ioctl(s, SIOCGIFINDEX, &ifr); - - addr.can_family = AF_CAN; - addr.can_ifindex = ifr.ifr_ifindex; - - connect(s, (struct sockaddr *)&addr, sizeof(addr)); - - (..) - - The broadcast manager socket is able to handle any number of in flight - transmissions or receive filters concurrently. The different RX/TX jobs are - distinguished by the unique can_id in each BCM message. However additional - CAN_BCM sockets are recommended to communicate on multiple CAN interfaces. - When the broadcast manager socket is bound to 'any' CAN interface (=> the - interface index is set to zero) the configured receive filters apply to any - CAN interface unless the sendto() syscall is used to overrule the 'any' CAN - interface index. When using recvfrom() instead of read() to retrieve BCM - socket messages the originating CAN interface is provided in can_ifindex. - - 4.2.1 Broadcast Manager operations - - The opcode defines the operation for the broadcast manager to carry out, - or details the broadcast managers response to several events, including - user requests. - - Transmit Operations (user space to broadcast manager): - - TX_SETUP: Create (cyclic) transmission task. - - TX_DELETE: Remove (cyclic) transmission task, requires only can_id. - - TX_READ: Read properties of (cyclic) transmission task for can_id. - - TX_SEND: Send one CAN frame. - - Transmit Responses (broadcast manager to user space): - - TX_STATUS: Reply to TX_READ request (transmission task configuration). - - TX_EXPIRED: Notification when counter finishes sending at initial interval - 'ival1'. Requires the TX_COUNTEVT flag to be set at TX_SETUP. - - Receive Operations (user space to broadcast manager): - - RX_SETUP: Create RX content filter subscription. - - RX_DELETE: Remove RX content filter subscription, requires only can_id. - - RX_READ: Read properties of RX content filter subscription for can_id. - - Receive Responses (broadcast manager to user space): - - RX_STATUS: Reply to RX_READ request (filter task configuration). - - RX_TIMEOUT: Cyclic message is detected to be absent (timer ival1 expired). - - RX_CHANGED: BCM message with updated CAN frame (detected content change). - Sent on first message received or on receipt of revised CAN messages. - - 4.2.2 Broadcast Manager message flags - - When sending a message to the broadcast manager the 'flags' element may - contain the following flag definitions which influence the behaviour: - - SETTIMER: Set the values of ival1, ival2 and count - - STARTTIMER: Start the timer with the actual values of ival1, ival2 - and count. Starting the timer leads simultaneously to emit a CAN frame. - - TX_COUNTEVT: Create the message TX_EXPIRED when count expires - - TX_ANNOUNCE: A change of data by the process is emitted immediately. - - TX_CP_CAN_ID: Copies the can_id from the message header to each - subsequent frame in frames. This is intended as usage simplification. For - TX tasks the unique can_id from the message header may differ from the - can_id(s) stored for transmission in the subsequent struct can_frame(s). - - RX_FILTER_ID: Filter by can_id alone, no frames required (nframes=0). - - RX_CHECK_DLC: A change of the DLC leads to an RX_CHANGED. - - RX_NO_AUTOTIMER: Prevent automatically starting the timeout monitor. - - RX_ANNOUNCE_RESUME: If passed at RX_SETUP and a receive timeout occurred, a - RX_CHANGED message will be generated when the (cyclic) receive restarts. - - TX_RESET_MULTI_IDX: Reset the index for the multiple frame transmission. - - RX_RTR_FRAME: Send reply for RTR-request (placed in op->frames[0]). - - 4.2.3 Broadcast Manager transmission timers - - Periodic transmission configurations may use up to two interval timers. - In this case the BCM sends a number of messages ('count') at an interval - 'ival1', then continuing to send at another given interval 'ival2'. When - only one timer is needed 'count' is set to zero and only 'ival2' is used. - When SET_TIMER and START_TIMER flag were set the timers are activated. - The timer values can be altered at runtime when only SET_TIMER is set. - - 4.2.4 Broadcast Manager message sequence transmission - - Up to 256 CAN frames can be transmitted in a sequence in the case of a cyclic - TX task configuration. The number of CAN frames is provided in the 'nframes' - element of the BCM message head. The defined number of CAN frames are added - as array to the TX_SETUP BCM configuration message. - - /* create a struct to set up a sequence of four CAN frames */ - struct { - struct bcm_msg_head msg_head; - struct can_frame frame[4]; - } mytxmsg; - - (..) - mytxmsg.msg_head.nframes = 4; - (..) - - write(s, &mytxmsg, sizeof(mytxmsg)); - - With every transmission the index in the array of CAN frames is increased - and set to zero at index overflow. - - 4.2.5 Broadcast Manager receive filter timers - - The timer values ival1 or ival2 may be set to non-zero values at RX_SETUP. - When the SET_TIMER flag is set the timers are enabled: - - ival1: Send RX_TIMEOUT when a received message is not received again within - the given time. When START_TIMER is set at RX_SETUP the timeout detection - is activated directly - even without a former CAN frame reception. - - ival2: Throttle the received message rate down to the value of ival2. This - is useful to reduce messages for the application when the signal inside the - CAN frame is stateless as state changes within the ival2 periode may get - lost. - - 4.2.6 Broadcast Manager multiplex message receive filter - - To filter for content changes in multiplex message sequences an array of more - than one CAN frames can be passed in a RX_SETUP configuration message. The - data bytes of the first CAN frame contain the mask of relevant bits that - have to match in the subsequent CAN frames with the received CAN frame. - If one of the subsequent CAN frames is matching the bits in that frame data - mark the relevant content to be compared with the previous received content. - Up to 257 CAN frames (multiplex filter bit mask CAN frame plus 256 CAN - filters) can be added as array to the TX_SETUP BCM configuration message. - - /* usually used to clear CAN frame data[] - beware of endian problems! */ - #define U64_DATA(p) (*(unsigned long long*)(p)->data) - - struct { - struct bcm_msg_head msg_head; - struct can_frame frame[5]; - } msg; - - msg.msg_head.opcode = RX_SETUP; - msg.msg_head.can_id = 0x42; - msg.msg_head.flags = 0; - msg.msg_head.nframes = 5; - U64_DATA(&msg.frame[0]) = 0xFF00000000000000ULL; /* MUX mask */ - U64_DATA(&msg.frame[1]) = 0x01000000000000FFULL; /* data mask (MUX 0x01) */ - U64_DATA(&msg.frame[2]) = 0x0200FFFF000000FFULL; /* data mask (MUX 0x02) */ - U64_DATA(&msg.frame[3]) = 0x330000FFFFFF0003ULL; /* data mask (MUX 0x33) */ - U64_DATA(&msg.frame[4]) = 0x4F07FC0FF0000000ULL; /* data mask (MUX 0x4F) */ - - write(s, &msg, sizeof(msg)); - - 4.2.7 Broadcast Manager CAN FD support - - The programming API of the CAN_BCM depends on struct can_frame which is - given as array directly behind the bcm_msg_head structure. To follow this - schema for the CAN FD frames a new flag 'CAN_FD_FRAME' in the bcm_msg_head - flags indicates that the concatenated CAN frame structures behind the - bcm_msg_head are defined as struct canfd_frame. - - struct { - struct bcm_msg_head msg_head; - struct canfd_frame frame[5]; - } msg; - - msg.msg_head.opcode = RX_SETUP; - msg.msg_head.can_id = 0x42; - msg.msg_head.flags = CAN_FD_FRAME; - msg.msg_head.nframes = 5; - (..) - - When using CAN FD frames for multiplex filtering the MUX mask is still - expected in the first 64 bit of the struct canfd_frame data section. - - 4.3 connected transport protocols (SOCK_SEQPACKET) - 4.4 unconnected transport protocols (SOCK_DGRAM) - - -5. SocketCAN core module -------------------------- - - The SocketCAN core module implements the protocol family - PF_CAN. CAN protocol modules are loaded by the core module at - runtime. The core module provides an interface for CAN protocol - modules to subscribe needed CAN IDs (see chapter 3.1). - - 5.1 can.ko module params - - - stats_timer: To calculate the SocketCAN core statistics - (e.g. current/maximum frames per second) this 1 second timer is - invoked at can.ko module start time by default. This timer can be - disabled by using stattimer=0 on the module commandline. - - - debug: (removed since SocketCAN SVN r546) - - 5.2 procfs content - - As described in chapter 3.1 the SocketCAN core uses several filter - lists to deliver received CAN frames to CAN protocol modules. These - receive lists, their filters and the count of filter matches can be - checked in the appropriate receive list. All entries contain the - device and a protocol module identifier: - - foo@bar:~$ cat /proc/net/can/rcvlist_all - - receive list 'rx_all': - (vcan3: no entry) - (vcan2: no entry) - (vcan1: no entry) - device can_id can_mask function userdata matches ident - vcan0 000 00000000 f88e6370 f6c6f400 0 raw - (any: no entry) - - In this example an application requests any CAN traffic from vcan0. - - rcvlist_all - list for unfiltered entries (no filter operations) - rcvlist_eff - list for single extended frame (EFF) entries - rcvlist_err - list for error message frames masks - rcvlist_fil - list for mask/value filters - rcvlist_inv - list for mask/value filters (inverse semantic) - rcvlist_sff - list for single standard frame (SFF) entries - - Additional procfs files in /proc/net/can - - stats - SocketCAN core statistics (rx/tx frames, match ratios, ...) - reset_stats - manual statistic reset - version - prints the SocketCAN core version and the ABI version - - 5.3 writing own CAN protocol modules - - To implement a new protocol in the protocol family PF_CAN a new - protocol has to be defined in include/linux/can.h . - The prototypes and definitions to use the SocketCAN core can be - accessed by including include/linux/can/core.h . - In addition to functions that register the CAN protocol and the - CAN device notifier chain there are functions to subscribe CAN - frames received by CAN interfaces and to send CAN frames: - - can_rx_register - subscribe CAN frames from a specific interface - can_rx_unregister - unsubscribe CAN frames from a specific interface - can_send - transmit a CAN frame (optional with local loopback) - - For details see the kerneldoc documentation in net/can/af_can.c or - the source code of net/can/raw.c or net/can/bcm.c . - -6. CAN network drivers ----------------------- - - Writing a CAN network device driver is much easier than writing a - CAN character device driver. Similar to other known network device - drivers you mainly have to deal with: - - - TX: Put the CAN frame from the socket buffer to the CAN controller. - - RX: Put the CAN frame from the CAN controller to the socket buffer. - - See e.g. at Documentation/networking/netdevices.txt . The differences - for writing CAN network device driver are described below: - - 6.1 general settings - - dev->type = ARPHRD_CAN; /* the netdevice hardware type */ - dev->flags = IFF_NOARP; /* CAN has no arp */ - - dev->mtu = CAN_MTU; /* sizeof(struct can_frame) -> legacy CAN interface */ - - or alternative, when the controller supports CAN with flexible data rate: - dev->mtu = CANFD_MTU; /* sizeof(struct canfd_frame) -> CAN FD interface */ - - The struct can_frame or struct canfd_frame is the payload of each socket - buffer (skbuff) in the protocol family PF_CAN. - - 6.2 local loopback of sent frames - - As described in chapter 3.2 the CAN network device driver should - support a local loopback functionality similar to the local echo - e.g. of tty devices. In this case the driver flag IFF_ECHO has to be - set to prevent the PF_CAN core from locally echoing sent frames - (aka loopback) as fallback solution: - - dev->flags = (IFF_NOARP | IFF_ECHO); - - 6.3 CAN controller hardware filters - - To reduce the interrupt load on deep embedded systems some CAN - controllers support the filtering of CAN IDs or ranges of CAN IDs. - These hardware filter capabilities vary from controller to - controller and have to be identified as not feasible in a multi-user - networking approach. The use of the very controller specific - hardware filters could make sense in a very dedicated use-case, as a - filter on driver level would affect all users in the multi-user - system. The high efficient filter sets inside the PF_CAN core allow - to set different multiple filters for each socket separately. - Therefore the use of hardware filters goes to the category 'handmade - tuning on deep embedded systems'. The author is running a MPC603e - @133MHz with four SJA1000 CAN controllers from 2002 under heavy bus - load without any problems ... - - 6.4 The virtual CAN driver (vcan) - - Similar to the network loopback devices, vcan offers a virtual local - CAN interface. A full qualified address on CAN consists of - - - a unique CAN Identifier (CAN ID) - - the CAN bus this CAN ID is transmitted on (e.g. can0) - - so in common use cases more than one virtual CAN interface is needed. - - The virtual CAN interfaces allow the transmission and reception of CAN - frames without real CAN controller hardware. Virtual CAN network - devices are usually named 'vcanX', like vcan0 vcan1 vcan2 ... - When compiled as a module the virtual CAN driver module is called vcan.ko - - Since Linux Kernel version 2.6.24 the vcan driver supports the Kernel - netlink interface to create vcan network devices. The creation and - removal of vcan network devices can be managed with the ip(8) tool: - - - Create a virtual CAN network interface: - $ ip link add type vcan - - - Create a virtual CAN network interface with a specific name 'vcan42': - $ ip link add dev vcan42 type vcan - - - Remove a (virtual CAN) network interface 'vcan42': - $ ip link del vcan42 - - 6.5 The CAN network device driver interface - - The CAN network device driver interface provides a generic interface - to setup, configure and monitor CAN network devices. The user can then - configure the CAN device, like setting the bit-timing parameters, via - the netlink interface using the program "ip" from the "IPROUTE2" - utility suite. The following chapter describes briefly how to use it. - Furthermore, the interface uses a common data structure and exports a - set of common functions, which all real CAN network device drivers - should use. Please have a look to the SJA1000 or MSCAN driver to - understand how to use them. The name of the module is can-dev.ko. - - 6.5.1 Netlink interface to set/get devices properties - - The CAN device must be configured via netlink interface. The supported - netlink message types are defined and briefly described in - "include/linux/can/netlink.h". CAN link support for the program "ip" - of the IPROUTE2 utility suite is available and it can be used as shown - below: - - - Setting CAN device properties: - - $ ip link set can0 type can help - Usage: ip link set DEVICE type can - [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] | - [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1 - phase-seg2 PHASE-SEG2 [ sjw SJW ] ] - - [ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] | - [ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1 - dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ] - - [ loopback { on | off } ] - [ listen-only { on | off } ] - [ triple-sampling { on | off } ] - [ one-shot { on | off } ] - [ berr-reporting { on | off } ] - [ fd { on | off } ] - [ fd-non-iso { on | off } ] - [ presume-ack { on | off } ] - - [ restart-ms TIME-MS ] - [ restart ] - - Where: BITRATE := { 1..1000000 } - SAMPLE-POINT := { 0.000..0.999 } - TQ := { NUMBER } - PROP-SEG := { 1..8 } - PHASE-SEG1 := { 1..8 } - PHASE-SEG2 := { 1..8 } - SJW := { 1..4 } - RESTART-MS := { 0 | NUMBER } - - - Display CAN device details and statistics: - - $ ip -details -statistics link show can0 - 2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP qlen 10 - link/can - can <TRIPLE-SAMPLING> state ERROR-ACTIVE restart-ms 100 - bitrate 125000 sample_point 0.875 - tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1 - sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 - clock 8000000 - re-started bus-errors arbit-lost error-warn error-pass bus-off - 41 17457 0 41 42 41 - RX: bytes packets errors dropped overrun mcast - 140859 17608 17457 0 0 0 - TX: bytes packets errors dropped carrier collsns - 861 112 0 41 0 0 - - More info to the above output: - - "<TRIPLE-SAMPLING>" - Shows the list of selected CAN controller modes: LOOPBACK, - LISTEN-ONLY, or TRIPLE-SAMPLING. - - "state ERROR-ACTIVE" - The current state of the CAN controller: "ERROR-ACTIVE", - "ERROR-WARNING", "ERROR-PASSIVE", "BUS-OFF" or "STOPPED" - - "restart-ms 100" - Automatic restart delay time. If set to a non-zero value, a - restart of the CAN controller will be triggered automatically - in case of a bus-off condition after the specified delay time - in milliseconds. By default it's off. - - "bitrate 125000 sample-point 0.875" - Shows the real bit-rate in bits/sec and the sample-point in the - range 0.000..0.999. If the calculation of bit-timing parameters - is enabled in the kernel (CONFIG_CAN_CALC_BITTIMING=y), the - bit-timing can be defined by setting the "bitrate" argument. - Optionally the "sample-point" can be specified. By default it's - 0.000 assuming CIA-recommended sample-points. - - "tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1" - Shows the time quanta in ns, propagation segment, phase buffer - segment 1 and 2 and the synchronisation jump width in units of - tq. They allow to define the CAN bit-timing in a hardware - independent format as proposed by the Bosch CAN 2.0 spec (see - chapter 8 of http://www.semiconductors.bosch.de/pdf/can2spec.pdf). - - "sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 - clock 8000000" - Shows the bit-timing constants of the CAN controller, here the - "sja1000". The minimum and maximum values of the time segment 1 - and 2, the synchronisation jump width in units of tq, the - bitrate pre-scaler and the CAN system clock frequency in Hz. - These constants could be used for user-defined (non-standard) - bit-timing calculation algorithms in user-space. - - "re-started bus-errors arbit-lost error-warn error-pass bus-off" - Shows the number of restarts, bus and arbitration lost errors, - and the state changes to the error-warning, error-passive and - bus-off state. RX overrun errors are listed in the "overrun" - field of the standard network statistics. - - 6.5.2 Setting the CAN bit-timing - - The CAN bit-timing parameters can always be defined in a hardware - independent format as proposed in the Bosch CAN 2.0 specification - specifying the arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" - and "sjw": - - $ ip link set canX type can tq 125 prop-seg 6 \ - phase-seg1 7 phase-seg2 2 sjw 1 - - If the kernel option CONFIG_CAN_CALC_BITTIMING is enabled, CIA - recommended CAN bit-timing parameters will be calculated if the bit- - rate is specified with the argument "bitrate": - - $ ip link set canX type can bitrate 125000 - - Note that this works fine for the most common CAN controllers with - standard bit-rates but may *fail* for exotic bit-rates or CAN system - clock frequencies. Disabling CONFIG_CAN_CALC_BITTIMING saves some - space and allows user-space tools to solely determine and set the - bit-timing parameters. The CAN controller specific bit-timing - constants can be used for that purpose. They are listed by the - following command: - - $ ip -details link show can0 - ... - sja1000: clock 8000000 tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 - - 6.5.3 Starting and stopping the CAN network device - - A CAN network device is started or stopped as usual with the command - "ifconfig canX up/down" or "ip link set canX up/down". Be aware that - you *must* define proper bit-timing parameters for real CAN devices - before you can start it to avoid error-prone default settings: - - $ ip link set canX up type can bitrate 125000 - - A device may enter the "bus-off" state if too many errors occurred on - the CAN bus. Then no more messages are received or sent. An automatic - bus-off recovery can be enabled by setting the "restart-ms" to a - non-zero value, e.g.: - - $ ip link set canX type can restart-ms 100 - - Alternatively, the application may realize the "bus-off" condition - by monitoring CAN error message frames and do a restart when - appropriate with the command: - - $ ip link set canX type can restart - - Note that a restart will also create a CAN error message frame (see - also chapter 3.3). - - 6.6 CAN FD (flexible data rate) driver support - - CAN FD capable CAN controllers support two different bitrates for the - arbitration phase and the payload phase of the CAN FD frame. Therefore a - second bit timing has to be specified in order to enable the CAN FD bitrate. - - Additionally CAN FD capable CAN controllers support up to 64 bytes of - payload. The representation of this length in can_frame.can_dlc and - canfd_frame.len for userspace applications and inside the Linux network - layer is a plain value from 0 .. 64 instead of the CAN 'data length code'. - The data length code was a 1:1 mapping to the payload length in the legacy - CAN frames anyway. The payload length to the bus-relevant DLC mapping is - only performed inside the CAN drivers, preferably with the helper - functions can_dlc2len() and can_len2dlc(). - - The CAN netdevice driver capabilities can be distinguished by the network - devices maximum transfer unit (MTU): - - MTU = 16 (CAN_MTU) => sizeof(struct can_frame) => 'legacy' CAN device - MTU = 72 (CANFD_MTU) => sizeof(struct canfd_frame) => CAN FD capable device - - The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. - N.B. CAN FD capable devices can also handle and send legacy CAN frames. - - When configuring CAN FD capable CAN controllers an additional 'data' bitrate - has to be set. This bitrate for the data phase of the CAN FD frame has to be - at least the bitrate which was configured for the arbitration phase. This - second bitrate is specified analogue to the first bitrate but the bitrate - setting keywords for the 'data' bitrate start with 'd' e.g. dbitrate, - dsample-point, dsjw or dtq and similar settings. When a data bitrate is set - within the configuration process the controller option "fd on" can be - specified to enable the CAN FD mode in the CAN controller. This controller - option also switches the device MTU to 72 (CANFD_MTU). - - The first CAN FD specification presented as whitepaper at the International - CAN Conference 2012 needed to be improved for data integrity reasons. - Therefore two CAN FD implementations have to be distinguished today: - - - ISO compliant: The ISO 11898-1:2015 CAN FD implementation (default) - - non-ISO compliant: The CAN FD implementation following the 2012 whitepaper - - Finally there are three types of CAN FD controllers: - - 1. ISO compliant (fixed) - 2. non-ISO compliant (fixed, like the M_CAN IP core v3.0.1 in m_can.c) - 3. ISO/non-ISO CAN FD controllers (switchable, like the PEAK PCAN-USB FD) - - The current ISO/non-ISO mode is announced by the CAN controller driver via - netlink and displayed by the 'ip' tool (controller option FD-NON-ISO). - The ISO/non-ISO-mode can be altered by setting 'fd-non-iso {on|off}' for - switchable CAN FD controllers only. - - Example configuring 500 kbit/s arbitration bitrate and 4 Mbit/s data bitrate: - - $ ip link set can0 up type can bitrate 500000 sample-point 0.75 \ - dbitrate 4000000 dsample-point 0.8 fd on - $ ip -details link show can0 - 5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UNKNOWN \ - mode DEFAULT group default qlen 10 - link/can promiscuity 0 - can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 - bitrate 500000 sample-point 0.750 - tq 50 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1 - pcan_usb_pro_fd: tseg1 1..64 tseg2 1..16 sjw 1..16 brp 1..1024 \ - brp-inc 1 - dbitrate 4000000 dsample-point 0.800 - dtq 12 dprop-seg 7 dphase-seg1 8 dphase-seg2 4 dsjw 1 - pcan_usb_pro_fd: dtseg1 1..16 dtseg2 1..8 dsjw 1..4 dbrp 1..1024 \ - dbrp-inc 1 - clock 80000000 - - Example when 'fd-non-iso on' is added on this switchable CAN FD adapter: - can <FD,FD-NON-ISO> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 - - 6.7 Supported CAN hardware - - Please check the "Kconfig" file in "drivers/net/can" to get an actual - list of the support CAN hardware. On the SocketCAN project website - (see chapter 7) there might be further drivers available, also for - older kernel versions. - -7. SocketCAN resources ------------------------ - - The Linux CAN / SocketCAN project resources (project site / mailing list) - are referenced in the MAINTAINERS file in the Linux source tree. - Search for CAN NETWORK [LAYERS|DRIVERS]. - -8. Credits ----------- - - Oliver Hartkopp (PF_CAN core, filters, drivers, bcm, SJA1000 driver) - Urs Thuermann (PF_CAN core, kernel integration, socket interfaces, raw, vcan) - Jan Kizka (RT-SocketCAN core, Socket-API reconciliation) - Wolfgang Grandegger (RT-SocketCAN core & drivers, Raw Socket-API reviews, - CAN device driver interface, MSCAN driver) - Robert Schwebel (design reviews, PTXdist integration) - Marc Kleine-Budde (design reviews, Kernel 2.6 cleanups, drivers) - Benedikt Spranger (reviews) - Thomas Gleixner (LKML reviews, coding style, posting hints) - Andrey Volkov (kernel subtree structure, ioctls, MSCAN driver) - Matthias Brukner (first SJA1000 CAN netdevice implementation Q2/2003) - Klaus Hitschler (PEAK driver integration) - Uwe Koppe (CAN netdevices with PF_PACKET approach) - Michael Schulze (driver layer loopback requirement, RT CAN drivers review) - Pavel Pisa (Bit-timing calculation) - Sascha Hauer (SJA1000 platform driver) - Sebastian Haas (SJA1000 EMS PCI driver) - Markus Plessing (SJA1000 EMS PCI driver) - Per Dalen (SJA1000 Kvaser PCI driver) - Sam Ravnborg (reviews, coding style, kbuild help) diff --git a/Documentation/networking/dsa/dsa.txt b/Documentation/networking/dsa/dsa.txt index b8b4075..25170ad 100644 --- a/Documentation/networking/dsa/dsa.txt +++ b/Documentation/networking/dsa/dsa.txt @@ -385,11 +385,6 @@ Switch configuration avoid relying on what a previous software agent such as a bootloader/firmware may have previously configured. -- set_addr: Some switches require the programming of the management interface's - Ethernet MAC address, switch drivers can also disable ageing of MAC addresses - on the management interface and "hardcode"/"force" this MAC address for the - CPU/management interface as an optimization - PHY devices and link management ------------------------------- diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt index 8781485..a4508ec 100644 --- a/Documentation/networking/filter.txt +++ b/Documentation/networking/filter.txt @@ -1134,7 +1134,7 @@ The verifier's knowledge about the variable offset consists of: mask and value; no bit should ever be 1 in both. For example, if a byte is read into a register from memory, the register's top 56 bits are known zero, while the low 8 are unknown - which is represented as the tnum (0x0; 0xff). If we -then OR this with 0x40, we get (0x40; 0xcf), then if we add 1 we get (0x0; +then OR this with 0x40, we get (0x40; 0xbf), then if we add 1 we get (0x0; 0x1ff), because of potential carries. Besides arithmetic, the register state can also be updated by conditional branches. For instance, if a SCALAR_VALUE is compared > 8, in the 'true' branch diff --git a/Documentation/networking/ieee802154.txt b/Documentation/networking/ieee802154.txt index 057e9fd..e74d8e1 100644 --- a/Documentation/networking/ieee802154.txt +++ b/Documentation/networking/ieee802154.txt @@ -97,6 +97,46 @@ The include/net/mac802154.h defines following functions: - void ieee802154_unregister_hw(struct ieee802154_hw *hw): freeing registered PHY + - void ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb, + u8 lqi): + telling 802.15.4 module there is a new received frame in the skb with + the RF Link Quality Indicator (LQI) from the hardware device + + - void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb, + bool ifs_handling): + telling 802.15.4 module the frame in the skb is or going to be + transmitted through the hardware device + +The device driver must implement the following callbacks in the IEEE 802.15.4 +operations structure at least: +struct ieee802154_ops { + ... + int (*start)(struct ieee802154_hw *hw); + void (*stop)(struct ieee802154_hw *hw); + ... + int (*xmit_async)(struct ieee802154_hw *hw, struct sk_buff *skb); + int (*ed)(struct ieee802154_hw *hw, u8 *level); + int (*set_channel)(struct ieee802154_hw *hw, u8 page, u8 channel); + ... +}; + + - int start(struct ieee802154_hw *hw): + handler that 802.15.4 module calls for the hardware device initialization. + + - void stop(struct ieee802154_hw *hw): + handler that 802.15.4 module calls for the hardware device cleanup. + + - int xmit_async(struct ieee802154_hw *hw, struct sk_buff *skb): + handler that 802.15.4 module calls for each frame in the skb going to be + transmitted through the hardware device. + + - int ed(struct ieee802154_hw *hw, u8 *level): + handler that 802.15.4 module calls for Energy Detection from the hardware + device. + + - int set_channel(struct ieee802154_hw *hw, u8 page, u8 channel): + set radio for listening on specific channel of the hardware device. + Moreover IEEE 802.15.4 device operations structure should be filled. Fake drivers diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index 7d4b159..90966c2 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -7,6 +7,7 @@ Contents: :maxdepth: 2 batman-adv + can kapi z8530book msg_zerocopy diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 46c7e10..3f2c40d 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -606,6 +606,7 @@ tcp_fastopen_blackhole_timeout_sec - INTEGER This time period will grow exponentially when more blackhole issues get detected right after Fastopen is re-enabled and will reset to initial value when the blackhole issue goes away. + 0 to disable the blackhole detection. By default, it is set to 1hr. tcp_syn_retries - INTEGER diff --git a/Documentation/networking/kapi.rst b/Documentation/networking/kapi.rst index 580289f..f03ae64 100644 --- a/Documentation/networking/kapi.rst +++ b/Documentation/networking/kapi.rst @@ -145,3 +145,27 @@ PHY Support .. kernel-doc:: drivers/net/phy/mdio_bus.c :internal: + +PHYLINK +------- + + PHYLINK interfaces traditional network drivers with PHYLIB, fixed-links, + and SFF modules (eg, hot-pluggable SFP) that may contain PHYs. PHYLINK + provides management of the link state and link modes. + +.. kernel-doc:: include/linux/phylink.h + :internal: + +.. kernel-doc:: drivers/net/phy/phylink.c + +SFP support +----------- + +.. kernel-doc:: drivers/net/phy/sfp-bus.c + :internal: + +.. kernel-doc:: include/linux/sfp.h + :internal: + +.. kernel-doc:: drivers/net/phy/sfp-bus.c + :export: diff --git a/Documentation/networking/netdev-features.txt b/Documentation/networking/netdev-features.txt index 7413eb0..c77f9d5 100644 --- a/Documentation/networking/netdev-features.txt +++ b/Documentation/networking/netdev-features.txt @@ -163,3 +163,12 @@ This requests that the NIC receive all possible frames, including errored frames (such as bad FCS, etc). This can be helpful when sniffing a link with bad packets on it. Some NICs may receive more packets if also put into normal PROMISC mode. + +* rx-gro-hw + +This requests that the NIC enables Hardware GRO (generic receive offload). +Hardware GRO is basically the exact reverse of TSO, and is generally +stricter than Hardware LRO. A packet stream merged by Hardware GRO must +be re-segmentable by GSO or TSO back to the exact original packet stream. +Hardware GRO is dependent on RXCSUM since every packet successfully merged +by hardware must also have the checksum verified by hardware. diff --git a/Documentation/networking/pktgen.txt b/Documentation/networking/pktgen.txt index 2c4e335..d2fd78f 100644 --- a/Documentation/networking/pktgen.txt +++ b/Documentation/networking/pktgen.txt @@ -12,8 +12,8 @@ suitable sample script and configure that. On a dual CPU: ps aux | grep pkt -root 129 0.3 0.0 0 0 ? SW 2003 523:20 [pktgen/0] -root 130 0.3 0.0 0 0 ? SW 2003 509:50 [pktgen/1] +root 129 0.3 0.0 0 0 ? SW 2003 523:20 [kpktgend_0] +root 130 0.3 0.0 0 0 ? SW 2003 509:50 [kpktgend_1] For monitoring and control pktgen creates: @@ -113,9 +113,16 @@ Configuring devices =================== This is done via the /proc interface, and most easily done via pgset as defined in the sample scripts. +You need to specify PGDEV environment variable to use functions from sample +scripts, i.e.: +export PGDEV=/proc/net/pktgen/eth4@0 +source samples/pktgen/functions.sh Examples: + pg_ctrl start starts injection. + pg_ctrl stop aborts injection. Also, ^C aborts generator. + pgset "clone_skb 1" sets the number of copies of the same packet pgset "clone_skb 0" use single SKB for all transmits pgset "burst 8" uses xmit_more API to queue 8 copies of the same @@ -165,8 +172,12 @@ Examples: IPSEC # IPsec encapsulation (needs CONFIG_XFRM) NODE_ALLOC # node specific memory allocation NO_TIMESTAMP # disable timestamping + pgset 'flag ![name]' Clear a flag to determine behaviour. + Note that you might need to use single quote in + interactive mode, so that your shell wouldn't expand + the specified flag as a history command. - pgset spi SPI_VALUE Set specific SA used to transform packet. + pgset "spi [SPI_VALUE]" Set specific SA used to transform packet. pgset "udp_src_min 9" set UDP source port min, If < udp_src_max, then cycle through the port range. @@ -207,8 +218,6 @@ Examples: pgset "tos XX" set former IPv4 TOS field (e.g. "tos 28" for AF11 no ECN, default 00) pgset "traffic_class XX" set former IPv6 TRAFFIC CLASS (e.g. "traffic_class B8" for EF no ECN, default 00) - pgset stop aborts injection. Also, ^C aborts generator. - pgset "rate 300M" set rate to 300 Mb/s pgset "ratep 1000000" set rate to 1Mpps diff --git a/Documentation/networking/xfrm_device.txt b/Documentation/networking/xfrm_device.txt new file mode 100644 index 0000000..50c34ca --- /dev/null +++ b/Documentation/networking/xfrm_device.txt @@ -0,0 +1,135 @@ + +=============================================== +XFRM device - offloading the IPsec computations +=============================================== +Shannon Nelson <shannon.nelson@oracle.com> + + +Overview +======== + +IPsec is a useful feature for securing network traffic, but the +computational cost is high: a 10Gbps link can easily be brought down +to under 1Gbps, depending on the traffic and link configuration. +Luckily, there are NICs that offer a hardware based IPsec offload which +can radically increase throughput and decrease CPU utilization. The XFRM +Device interface allows NIC drivers to offer to the stack access to the +hardware offload. + +Userland access to the offload is typically through a system such as +libreswan or KAME/raccoon, but the iproute2 'ip xfrm' command set can +be handy when experimenting. An example command might look something +like this: + + ip x s add proto esp dst 14.0.0.70 src 14.0.0.52 spi 0x07 mode transport \ + reqid 0x07 replay-window 32 \ + aead 'rfc4106(gcm(aes))' 0x44434241343332312423222114131211f4f3f2f1 128 \ + sel src 14.0.0.52/24 dst 14.0.0.70/24 proto tcp \ + offload dev eth4 dir in + +Yes, that's ugly, but that's what shell scripts and/or libreswan are for. + + + +Callbacks to implement +====================== + +/* from include/linux/netdevice.h */ +struct xfrmdev_ops { + int (*xdo_dev_state_add) (struct xfrm_state *x); + void (*xdo_dev_state_delete) (struct xfrm_state *x); + void (*xdo_dev_state_free) (struct xfrm_state *x); + bool (*xdo_dev_offload_ok) (struct sk_buff *skb, + struct xfrm_state *x); + void (*xdo_dev_state_advance_esn) (struct xfrm_state *x); +}; + +The NIC driver offering ipsec offload will need to implement these +callbacks to make the offload available to the network stack's +XFRM subsytem. Additionally, the feature bits NETIF_F_HW_ESP and +NETIF_F_HW_ESP_TX_CSUM will signal the availability of the offload. + + + +Flow +==== + +At probe time and before the call to register_netdev(), the driver should +set up local data structures and XFRM callbacks, and set the feature bits. +The XFRM code's listener will finish the setup on NETDEV_REGISTER. + + adapter->netdev->xfrmdev_ops = &ixgbe_xfrmdev_ops; + adapter->netdev->features |= NETIF_F_HW_ESP; + adapter->netdev->hw_enc_features |= NETIF_F_HW_ESP; + +When new SAs are set up with a request for "offload" feature, the +driver's xdo_dev_state_add() will be given the new SA to be offloaded +and an indication of whether it is for Rx or Tx. The driver should + - verify the algorithm is supported for offloads + - store the SA information (key, salt, target-ip, protocol, etc) + - enable the HW offload of the SA + +The driver can also set an offload_handle in the SA, an opaque void pointer +that can be used to convey context into the fast-path offload requests. + + xs->xso.offload_handle = context; + + +When the network stack is preparing an IPsec packet for an SA that has +been setup for offload, it first calls into xdo_dev_offload_ok() with +the skb and the intended offload state to ask the driver if the offload +will serviceable. This can check the packet information to be sure the +offload can be supported (e.g. IPv4 or IPv6, no IPv4 options, etc) and +return true of false to signify its support. + +When ready to send, the driver needs to inspect the Tx packet for the +offload information, including the opaque context, and set up the packet +send accordingly. + + xs = xfrm_input_state(skb); + context = xs->xso.offload_handle; + set up HW for send + +The stack has already inserted the appropriate IPsec headers in the +packet data, the offload just needs to do the encryption and fix up the +header values. + + +When a packet is received and the HW has indicated that it offloaded a +decryption, the driver needs to add a reference to the decoded SA into +the packet's skb. At this point the data should be decrypted but the +IPsec headers are still in the packet data; they are removed later up +the stack in xfrm_input(). + + find and hold the SA that was used to the Rx skb + get spi, protocol, and destination IP from packet headers + xs = find xs from (spi, protocol, dest_IP) + xfrm_state_hold(xs); + + store the state information into the skb + skb->sp = secpath_dup(skb->sp); + skb->sp->xvec[skb->sp->len++] = xs; + skb->sp->olen++; + + indicate the success and/or error status of the offload + xo = xfrm_offload(skb); + xo->flags = CRYPTO_DONE; + xo->status = crypto_status; + + hand the packet to napi_gro_receive() as usual + +In ESN mode, xdo_dev_state_advance_esn() is called from xfrm_replay_advance_esn(). +Driver will check packet seq number and update HW ESN state machine if needed. + +When the SA is removed by the user, the driver's xdo_dev_state_delete() +is asked to disable the offload. Later, xdo_dev_state_free() is called +from a garbage collection routine after all reference counts to the state +have been removed and any remaining resources can be cleared for the +offload state. How these are used by the driver will depend on specific +hardware needs. + +As a netdev is set to DOWN the XFRM stack's netdev listener will call +xdo_dev_state_delete() and xdo_dev_state_free() on any remaining offloaded +states. + + diff --git a/Documentation/networking/xfrm_proc.txt b/Documentation/networking/xfrm_proc.txt index d0d8baf..2eae619 100644 --- a/Documentation/networking/xfrm_proc.txt +++ b/Documentation/networking/xfrm_proc.txt @@ -5,13 +5,15 @@ Masahide NAKAMURA <nakam@linux-ipv6.org> Transformation Statistics ------------------------- -xfrm_proc is a statistics shown factor dropped by transformation -for developer. -It is a counter designed from current transformation source code -and defined like linux private MIB. -Inbound statistics -~~~~~~~~~~~~~~~~~~ +The xfrm_proc code is a set of statistics showing numbers of packets +dropped by the transformation code and why. These counters are defined +as part of the linux private MIB. These counters can be viewed in +/proc/net/xfrm_stat. + + +Inbound errors +~~~~~~~~~~~~~~ XfrmInError: All errors which is not matched others XfrmInBufferError: @@ -46,6 +48,10 @@ XfrmInPolBlock: Policy discards XfrmInPolError: Policy error +XfrmAcquireError: + State hasn't been fully acquired before use +XfrmFwdHdrError: + Forward routing of a packet is not allowed Outbound errors ~~~~~~~~~~~~~~~ @@ -72,3 +78,5 @@ XfrmOutPolDead: Policy is dead XfrmOutPolError: Policy error +XfrmOutStateInvalid: + State is invalid, perhaps expired diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt index b67044a..35c62f5 100644 --- a/Documentation/sysctl/net.txt +++ b/Documentation/sysctl/net.txt @@ -95,7 +95,9 @@ dev_weight -------------- The maximum number of packets that kernel can handle on a NAPI interrupt, -it's a Per-CPU variable. +it's a Per-CPU variable. For drivers that support LRO or GRO_HW, a hardware +aggregated packet is counted as one packet in this context. + Default: 64 dev_weight_rx_bias |
