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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
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This document describes the implementation of the in-kernel
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Device Tree resolver, residing in drivers/of/resolver.c and is a
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companion document to Documentation/devicetree/dt-object-internal.txt[1]
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How the resolver works
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----------------------
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The resolver is given as an input an arbitrary tree compiled with the
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proper dtc option and having a /plugin/ tag. This generates the
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appropriate __fixups__ & __local_fixups__ nodes as described in [1].
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In sequence the resolver works by the following steps:
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1. Get the maximum device tree phandle value from the live tree + 1.
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2. Adjust all the local phandles of the tree to resolve by that amount.
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3. Using the __local__fixups__ node information adjust all local references
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by the same amount.
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4. For each property in the __fixups__ node locate the node it references
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in the live tree. This is the label used to tag the node.
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5. Retrieve the phandle of the target of the fixup.
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6. For each fixup in the property locate the node:property:offset location
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and replace it with the phandle value.
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