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There's a variety of ways 'Devicetree' has been written. This is most evident in the documentation build contents where we have 'Device Tree', 'DeviceTree', etc. The DT spec has somewhat standardized on 'Devicetree', so let's use that. Cc: Frank Rowand <frowand.list@gmail.com> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Signed-off-by: Rob Herring <robh@kernel.org> Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/20210325164713.1296407-5-robh@kernel.org
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27 lines
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.. SPDX-License-Identifier: GPL-2.0
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=================================
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Devicetree Dynamic Resolver Notes
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=================================
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This document describes the implementation of the in-kernel
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DeviceTree resolver, residing in drivers/of/resolver.c
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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.
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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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