mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 01:34:14 +08:00
7941b27b16
Introduce support for dynamic device tree resolution. Using it, it is possible to prepare a device tree that's been loaded on runtime to be modified and inserted at the kernel live tree. Export of of_resolve and bug fix of double free by Guenter Roeck <groeck@juniper.net> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com> [grant.likely: Don't need to select CONFIG_OF_DYNAMIC and CONFIG_OF_DEVICE] [grant.likely: Don't need to depend on OF or !SPARC] [grant.likely: Factor out duplicate code blocks into single function] Signed-off-by: Grant Likely <grant.likely@linaro.org>
26 lines
1.1 KiB
Plaintext
26 lines
1.1 KiB
Plaintext
Device Tree Dynamic Resolver Notes
|
|
----------------------------------
|
|
|
|
This document describes the implementation of the in-kernel
|
|
Device Tree resolver, residing in drivers/of/resolver.c and is a
|
|
companion document to Documentation/devicetree/dt-object-internal.txt[1]
|
|
|
|
How the resolver works
|
|
----------------------
|
|
|
|
The resolver is given as an input an arbitrary tree compiled with the
|
|
proper dtc option and having a /plugin/ tag. This generates the
|
|
appropriate __fixups__ & __local_fixups__ nodes as described in [1].
|
|
|
|
In sequence the resolver works by the following steps:
|
|
|
|
1. Get the maximum device tree phandle value from the live tree + 1.
|
|
2. Adjust all the local phandles of the tree to resolve by that amount.
|
|
3. Using the __local__fixups__ node information adjust all local references
|
|
by the same amount.
|
|
4. For each property in the __fixups__ node locate the node it references
|
|
in the live tree. This is the label used to tag the node.
|
|
5. Retrieve the phandle of the target of the fixup.
|
|
6. For each fixup in the property locate the node:property:offset location
|
|
and replace it with the phandle value.
|