linux/Documentation/ABI/testing/sysfs-firmware-ofw

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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.