diff options
author | Pantelis Antoniou <pantelis.antoniou@konsulko.com> | 2014-07-04 19:59:20 +0300 |
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committer | Mark Brown <broonie@kernel.org> | 2015-02-20 23:41:16 +0900 |
commit | cf77cbddf4794311ca069c5e67428434a86a8021 (patch) | |
tree | e7a854931350928af7eee157e1e239a724d266b4 /Documentation | |
parent | 33ef56d1b95d9b628f9ed78c34d40b746668855e (diff) |
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>
(cherry picked from commit 7941b27b16e3282f6ec8817e36492f1deec753a7)
Signed-off-by: Mark Brown <broonie@kernel.org>
Conflicts:
drivers/of/Kconfig
drivers/of/Makefile
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/devicetree/dynamic-resolution-notes.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/devicetree/dynamic-resolution-notes.txt b/Documentation/devicetree/dynamic-resolution-notes.txt new file mode 100644 index 000000000000..083d23262abe --- /dev/null +++ b/Documentation/devicetree/dynamic-resolution-notes.txt @@ -0,0 +1,25 @@ +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. |