diff options
| -rw-r--r-- | Documentation/devicetree/of_selftest.txt | 211 | ||||
| -rw-r--r-- | drivers/of/base.c | 16 | ||||
| -rw-r--r-- | drivers/of/dynamic.c | 3 | ||||
| -rw-r--r-- | drivers/of/fdt.c | 14 |
4 files changed, 237 insertions, 7 deletions
diff --git a/Documentation/devicetree/of_selftest.txt b/Documentation/devicetree/of_selftest.txt new file mode 100644 index 0000000..3a2f54d --- /dev/null +++ b/Documentation/devicetree/of_selftest.txt @@ -0,0 +1,211 @@ +Open Firmware Device Tree Selftest +---------------------------------- + +Author: Gaurav Minocha <gaurav.minocha.os@gmail.com> + +1. Introduction + +This document explains how the test data required for executing OF selftest +is attached to the live tree dynamically, independent of the machine's +architecture. + +It is recommended to read the following documents before moving ahead. + +[1] Documentation/devicetree/usage-model.txt +[2] http://www.devicetree.org/Device_Tree_Usage + +OF Selftest has been designed to test the interface (include/linux/of.h) +provided to device driver developers to fetch the device information..etc. +from the unflattened device tree data structure. This interface is used by +most of the device drivers in various use cases. + + +2. Test-data + +The Device Tree Source file (drivers/of/testcase-data/testcases.dts) contains +the test data required for executing the unit tests automated in +drivers/of/selftests.c. Currently, following Device Tree Source Include files +(.dtsi) are included in testcase.dts: + +drivers/of/testcase-data/tests-interrupts.dtsi +drivers/of/testcase-data/tests-platform.dtsi +drivers/of/testcase-data/tests-phandle.dtsi +drivers/of/testcase-data/tests-match.dtsi + +When the kernel is build with OF_SELFTEST enabled, then the following make rule + +$(obj)/%.dtb: $(src)/%.dts FORCE + $(call if_changed_dep, dtc) + +is used to compile the DT source file (testcase.dts) into a binary blob +(testcase.dtb), also referred as flattened DT. + +After that, using the following rule the binary blob above is wrapped as an +assembly file (testcase.dtb.S). + +$(obj)/%.dtb.S: $(obj)/%.dtb + $(call cmd, dt_S_dtb) + +The assembly file is compiled into an object file (testcase.dtb.o), and is +linked into the kernel image. + + +2.1. Adding the test data + +Un-flattened device tree structure: + +Un-flattened device tree consists of connected device_node(s) in form of a tree +structure described below. + +// following struct members are used to construct the tree +struct device_node { + ... + struct device_node *parent; + struct device_node *child; + struct device_node *sibling; + struct device_node *allnext; /* next in list of all nodes */ + ... + }; + +Figure 1, describes a generic structure of machine’s un-flattened device tree +considering only child and sibling pointers. There exists another pointer, +*parent, that is used to traverse the tree in the reverse direction. So, at +a particular level the child node and all the sibling nodes will have a parent +pointer pointing to a common node (e.g. child1, sibling2, sibling3, sibling4’s +parent points to root node) + +root (‘/’) + | +child1 -> sibling2 -> sibling3 -> sibling4 -> null + | | | | + | | | null + | | | + | | child31 -> sibling32 -> null + | | | | + | | null null + | | + | child21 -> sibling22 -> sibling23 -> null + | | | | + | null null null + | +child11 -> sibling12 -> sibling13 -> sibling14 -> null + | | | | + | | | null + | | | + null null child131 -> null + | + null + +Figure 1: Generic structure of un-flattened device tree + + +*allnext: it is used to link all the nodes of DT into a list. So, for the + above tree the list would be as follows: + +root->child1->child11->sibling12->sibling13->child131->sibling14->sibling2-> +child21->sibling22->sibling23->sibling3->child31->sibling32->sibling4->null + +Before executing OF selftest, it is required to attach the test data to +machine's device tree (if present). So, when selftest_data_add() is called, +at first it reads the flattened device tree data linked into the kernel image +via the following kernel symbols: + +__dtb_testcases_begin - address marking the start of test data blob +__dtb_testcases_end - address marking the end of test data blob + +Secondly, it calls of_fdt_unflatten_device_tree() to unflatten the flattened +blob. And finally, if the machine’s device tree (i.e live tree) is present, +then it attaches the unflattened test data tree to the live tree, else it +attaches itself as a live device tree. + +attach_node_and_children() uses of_attach_node() to attach the nodes into the +live tree as explained below. To explain the same, the test data tree described + in Figure 2 is attached to the live tree described in Figure 1. + +root (‘/’) + | + testcase-data + | + test-child0 -> test-sibling1 -> test-sibling2 -> test-sibling3 -> null + | | | | + test-child01 null null null + + +allnext list: + +root->testcase-data->test-child0->test-child01->test-sibling1->test-sibling2 +->test-sibling3->null + +Figure 2: Example test data tree to be attached to live tree. + +According to the scenario above, the live tree is already present so it isn’t +required to attach the root(‘/’) node. All other nodes are attached by calling +of_attach_node() on each node. + +In the function of_attach_node(), the new node is attached as the child of the +given parent in live tree. But, if parent already has a child then the new node +replaces the current child and turns it into its sibling. So, when the testcase +data node is attached to the live tree above (Figure 1), the final structure is + as shown in Figure 3. + +root (‘/’) + | +testcase-data -> child1 -> sibling2 -> sibling3 -> sibling4 -> null + | | | | | + (...) | | | null + | | child31 -> sibling32 -> null + | | | | + | | null null + | | + | child21 -> sibling22 -> sibling23 -> null + | | | | + | null null null + | + child11 -> sibling12 -> sibling13 -> sibling14 -> null + | | | | + null null | null + | + child131 -> null + | + null +----------------------------------------------------------------------- + +root (‘/’) + | +testcase-data -> child1 -> sibling2 -> sibling3 -> sibling4 -> null + | | | | | + | (...) (...) (...) null + | +test-sibling3 -> test-sibling2 -> test-sibling1 -> test-child0 -> null + | | | | + null null null test-child01 + + +Figure 3: Live device tree structure after attaching the testcase-data. + + +Astute readers would have noticed that test-child0 node becomes the last +sibling compared to the earlier structure (Figure 2). After attaching first +test-child0 the test-sibling1 is attached that pushes the child node +(i.e. test-child0) to become a sibling and makes itself a child node, + as mentioned above. + +If a duplicate node is found (i.e. if a node with same full_name property is +already present in the live tree), then the node isn’t attached rather its +properties are updated to the live tree’s node by calling the function +update_node_properties(). + + +2.2. Removing the test data + +Once the test case execution is complete, selftest_data_remove is called in +order to remove the device nodes attached initially (first the leaf nodes are +detached and then moving up the parent nodes are removed, and eventually the +whole tree). selftest_data_remove() calls detach_node_and_children() that uses +of_detach_node() to detach the nodes from the live device tree. + +To detach a node, of_detach_node() first updates all_next linked list, by +attaching the previous node’s allnext to current node’s allnext pointer. And +then, it either updates the child pointer of given node’s parent to its +sibling or attaches the previous sibling to the given node’s sibling, as +appropriate. That is it :) diff --git a/drivers/of/base.c b/drivers/of/base.c index d8574ad..293ed4b 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -138,6 +138,9 @@ int __of_add_property_sysfs(struct device_node *np, struct property *pp) /* Important: Don't leak passwords */ bool secure = strncmp(pp->name, "security-", 9) == 0; + if (!IS_ENABLED(CONFIG_SYSFS)) + return 0; + if (!of_kset || !of_node_is_attached(np)) return 0; @@ -158,6 +161,9 @@ int __of_attach_node_sysfs(struct device_node *np) struct property *pp; int rc; + if (!IS_ENABLED(CONFIG_SYSFS)) + return 0; + if (!of_kset) return 0; @@ -1713,6 +1719,9 @@ int __of_remove_property(struct device_node *np, struct property *prop) void __of_remove_property_sysfs(struct device_node *np, struct property *prop) { + if (!IS_ENABLED(CONFIG_SYSFS)) + return; + /* at early boot, bail here and defer setup to of_init() */ if (of_kset && of_node_is_attached(np)) sysfs_remove_bin_file(&np->kobj, &prop->attr); @@ -1777,6 +1786,9 @@ int __of_update_property(struct device_node *np, struct property *newprop, void __of_update_property_sysfs(struct device_node *np, struct property *newprop, struct property *oldprop) { + if (!IS_ENABLED(CONFIG_SYSFS)) + return; + /* At early boot, bail out and defer setup to of_init() */ if (!of_kset) return; @@ -1847,6 +1859,7 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align)) { struct property *pp; + of_aliases = of_find_node_by_path("/aliases"); of_chosen = of_find_node_by_path("/chosen"); if (of_chosen == NULL) of_chosen = of_find_node_by_path("/chosen@0"); @@ -1862,7 +1875,6 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align)) of_stdout = of_find_node_by_path(name); } - of_aliases = of_find_node_by_path("/aliases"); if (!of_aliases) return; @@ -1986,7 +1998,7 @@ bool of_console_check(struct device_node *dn, char *name, int index) { if (!dn || dn != of_stdout || console_set_on_cmdline) return false; - return add_preferred_console(name, index, NULL); + return !add_preferred_console(name, index, NULL); } EXPORT_SYMBOL_GPL(of_console_check); diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 54fecc4..f297891 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -45,6 +45,9 @@ void __of_detach_node_sysfs(struct device_node *np) { struct property *pp; + if (!IS_ENABLED(CONFIG_SYSFS)) + return; + BUG_ON(!of_node_is_initialized(np)); if (!of_kset) return; diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 79cb831..d1ffca8 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size) { const u64 phys_offset = __pa(PAGE_OFFSET); - base &= PAGE_MASK; + + if (!PAGE_ALIGNED(base)) { + size -= PAGE_SIZE - (base & ~PAGE_MASK); + base = PAGE_ALIGN(base); + } size &= PAGE_MASK; if (base > MAX_PHYS_ADDR) { @@ -937,10 +941,10 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size) return; } - if (base + size > MAX_PHYS_ADDR) { - pr_warning("Ignoring memory range 0x%lx - 0x%llx\n", - ULONG_MAX, base + size); - size = MAX_PHYS_ADDR - base; + if (base + size - 1 > MAX_PHYS_ADDR) { + pr_warning("Ignoring memory range 0x%llx - 0x%llx\n", + ((u64)MAX_PHYS_ADDR) + 1, base + size); + size = MAX_PHYS_ADDR - base + 1; } if (base + size < phys_offset) { |
