summaryrefslogtreecommitdiff
path: root/Documentation/ABI/testing/sysfs-firmware-ofw
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/ABI/testing/sysfs-firmware-ofw')
-rw-r--r--Documentation/ABI/testing/sysfs-firmware-ofw28
1 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-ofw b/Documentation/ABI/testing/sysfs-firmware-ofw
new file mode 100644
index 000000000..f562b188e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-ofw
@@ -0,0 +1,28 @@
+What: /sys/firmware/devicetree/*
+Date: November 2013
+Contact: Grant Likely <grant.likely@linaro.org>
+Description:
+ When using OpenFirmware or a Flattened Device Tree to enumerate
+ hardware, the device tree structure will be exposed in this
+ directory.
+
+ It is possible for multiple device-tree directories to exist.
+ Some device drivers use a separate detached device tree which
+ have no attachment to the system tree and will appear in a
+ different subdirectory under /sys/firmware/devicetree.
+
+ Userspace must not use the /sys/firmware/devicetree/base
+ path directly, but instead should follow /proc/device-tree
+ symlink. It is possible that the absolute path will change
+ in the future, but the symlink is the stable ABI.
+
+ The /proc/device-tree symlink replaces the devicetree /proc
+ filesystem support, and has largely the same semantics and
+ should be compatible with existing userspace.
+
+ The contents of /sys/firmware/devicetree/ is a
+ hierarchy of directories, one per device tree node. The
+ directory name is the resolved path component name (node
+ name plus address). Properties are represented as files
+ in the directory. The contents of each file is the exact
+ binary data from the device tree.