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authorLinus Torvalds <torvalds@linux-foundation.org>2016-12-13 12:11:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-13 12:11:01 -0800
commitb78b499a67c3f77aeb6cd0b54724bc38b141255d (patch)
tree8ebdb5303bb1552577182d9fe4086910b8648d22 /Documentation/trace
parent098c30557a9a19827240aaadc137e4668157dc6b (diff)
parent190cc65e912de7e8f7ebddcecfbf55a610281a8c (diff)
downloadop-kernel-dev-b78b499a67c3f77aeb6cd0b54724bc38b141255d.zip
op-kernel-dev-b78b499a67c3f77aeb6cd0b54724bc38b141255d.tar.gz
Merge tag 'char-misc-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH: "Here's the big char/misc driver patches for 4.10-rc1. Lots of tiny changes over lots of "minor" driver subsystems, the largest being some new FPGA drivers. Other than that, a few other new drivers, but no new driver subsystems added for this kernel cycle, a nice change. All of these have been in linux-next with no reported issues" * tag 'char-misc-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (107 commits) uio-hv-generic: store physical addresses instead of virtual Tools: hv: kvp: configurable external scripts path uio-hv-generic: new userspace i/o driver for VMBus vmbus: add support for dynamic device id's hv: change clockevents unbind tactics hv: acquire vmbus_connection.channel_mutex in vmbus_free_channels() hyperv: Fix spelling of HV_UNKOWN mei: bus: enable non-blocking RX mei: fix the back to back interrupt handling mei: synchronize irq before initiating a reset. VME: Remove shutdown entry from vme_driver auxdisplay: ht16k33: select framebuffer helper modules MAINTAINERS: add git url for fpga fpga: Clarify how write_init works streaming modes fpga zynq: Fix incorrect ISR state on bootup fpga zynq: Remove priv->dev fpga zynq: Add missing \n to messages fpga: Add COMPILE_TEST to all drivers uio: pruss: add clk_disable() char/pcmcia: add some error checking in scr24x_read() ...
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/intel_th.txt22
-rw-r--r--Documentation/trace/stm.txt37
2 files changed, 56 insertions, 3 deletions
diff --git a/Documentation/trace/intel_th.txt b/Documentation/trace/intel_th.txt
index f7fc5ba..f92070e 100644
--- a/Documentation/trace/intel_th.txt
+++ b/Documentation/trace/intel_th.txt
@@ -97,3 +97,25 @@ $ echo 0 > /sys/bus/intel_th/devices/0-msc0/active
# and now you can collect the trace from the device node:
$ cat /dev/intel_th0/msc0 > my_stp_trace
+
+Host Debugger Mode
+==================
+
+It is possible to configure the Trace Hub and control its trace
+capture from a remote debug host, which should be connected via one of
+the hardware debugging interfaces, which will then be used to both
+control Intel Trace Hub and transfer its trace data to the debug host.
+
+The driver needs to be told that such an arrangement is taking place
+so that it does not touch any capture/port configuration and avoids
+conflicting with the debug host's configuration accesses. The only
+activity that the driver will perform in this mode is collecting
+software traces to the Software Trace Hub (an stm class device). The
+user is still responsible for setting up adequate master/channel
+mappings that the decoder on the receiving end would recognize.
+
+In order to enable the host mode, set the 'host_mode' parameter of the
+'intel_th' kernel module to 'y'. None of the virtual output devices
+will show up on the intel_th bus. Also, trace configuration and
+capture controlling attribute groups of the 'gth' device will not be
+exposed. The 'sth' device will operate as usual.
diff --git a/Documentation/trace/stm.txt b/Documentation/trace/stm.txt
index ea035f9..11cff47 100644
--- a/Documentation/trace/stm.txt
+++ b/Documentation/trace/stm.txt
@@ -69,12 +69,43 @@ stm device's channel mmio region is 64 bytes and hardware page size is
width==64, you should be able to mmap() one page on this file
descriptor and obtain direct access to an mmio region for 64 channels.
+Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM
+[2].
+
+stm_source
+==========
+
For kernel-based trace sources, there is "stm_source" device
class. Devices of this class can be connected and disconnected to/from
-stm devices at runtime via a sysfs attribute.
+stm devices at runtime via a sysfs attribute called "stm_source_link"
+by writing the name of the desired stm device there, for example:
-Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM
-[2].
+$ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link
+
+For examples on how to use stm_source interface in the kernel, refer
+to stm_console or stm_heartbeat drivers.
+
+Each stm_source device will need to assume a master and a range of
+channels, depending on how many channels it requires. These are
+allocated for the device according to the policy configuration. If
+there's a node in the root of the policy directory that matches the
+stm_source device's name (for example, "console"), this node will be
+used to allocate master and channel numbers. If there's no such policy
+node, the stm core will pick the first contiguous chunk of channels
+within the first available master. Note that the node must exist
+before the stm_source device is connected to its stm device.
+
+stm_console
+===========
+
+One implementation of this interface also used in the example above is
+the "stm_console" driver, which basically provides a one-way console
+for kernel messages over an stm device.
+
+To configure the master/channel pair that will be assigned to this
+console in the STP stream, create a "console" policy entry (see the
+beginning of this text on how to do that). When initialized, it will
+consume one channel.
[1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf
[2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html
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