linux-hardened/Documentation/devicetree/dynamic-resolution-notes.txt
Pantelis Antoniou 7941b27b16 of: Introduce Device Tree resolve support.
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>
2014-10-04 21:24:26 +01:00

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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.