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https://github.com/RGBCube/serenity
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613cfb31b1
Using the walk_device_tree helper, we can walk the device tree from the beginning looking for a specific property node. It's still missing the ability to get property lists, string lists, and property-specific data.
71 lines
3.4 KiB
C++
71 lines
3.4 KiB
C++
/*
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* Copyright (c) 2021-2023, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Endian.h>
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#include <AK/Error.h>
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#include <AK/Function.h>
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#include <AK/IterationDecision.h>
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#include <AK/StringView.h>
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#include <AK/Types.h>
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namespace DeviceTree {
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html
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struct FlattenedDeviceTreeHeader {
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BigEndian<u32> magic; // 0xDOODFEED (BE)
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BigEndian<u32> totalsize; // Total size of entire blob including padding b/w and after fields
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BigEndian<u32> off_dt_struct; // Offset of StructureBlock from beginning of header
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#sect-fdt-structure-block
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BigEndian<u32> off_dt_strings; // Offset of StringsBlock from beginning of header
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#sect-fdt-strings-block
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BigEndian<u32> off_mem_rsvmap; // Offset of MemoryReservationBlock from beginning of header
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BigEndian<u32> version; // 0.3 spec defines version 17
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BigEndian<u32> last_comp_version; // 0.3 spec back-compatible with version 16, mandated to be 16
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BigEndian<u32> boot_cpuid_phys; // Physical ID given in `reg` property of CPU node of boot cpu
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BigEndian<u32> size_dt_strings; // Length in bytes of StringsBlock
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BigEndian<u32> size_dt_struct; // Length in bytes of StructureBlock
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};
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static_assert(sizeof(FlattenedDeviceTreeHeader) == 40, "FDT Header size must match specification");
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#format
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struct FlattenedDeviceTreeReserveEntry {
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BigEndian<u64> address;
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BigEndian<u64> size;
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bool operator==(FlattenedDeviceTreeReserveEntry const& other) const { return other.address == address && other.size == size; }
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};
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static_assert(sizeof(FlattenedDeviceTreeReserveEntry) == 16, "FDT Memory Reservation entry size must match specification");
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// https://devicetree-specification.readthedocs.io/en/v0.3/flattened-format.html#lexical-structure
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enum FlattenedDeviceTreeTokenType : u32 {
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BeginNode = 1,
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EndNode = 2,
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Property = 3,
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NoOp = 4,
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End = 9
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};
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struct DeviceTreeCallbacks {
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Function<ErrorOr<IterationDecision>(StringView)> on_node_begin;
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Function<ErrorOr<IterationDecision>(StringView)> on_node_end;
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Function<ErrorOr<IterationDecision>(StringView, ReadonlyBytes)> on_property;
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Function<ErrorOr<IterationDecision>()> on_noop;
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Function<ErrorOr<void>()> on_end;
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};
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ErrorOr<void> walk_device_tree(FlattenedDeviceTreeHeader const&, ReadonlyBytes raw_device_tree, DeviceTreeCallbacks);
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template<typename T>
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ErrorOr<T> slow_get_property(StringView name, FlattenedDeviceTreeHeader const&, ReadonlyBytes raw_device_tree);
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extern template ErrorOr<void> slow_get_property(StringView name, FlattenedDeviceTreeHeader const& header, ReadonlyBytes raw_device_tree);
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extern template ErrorOr<u32> slow_get_property(StringView name, FlattenedDeviceTreeHeader const& header, ReadonlyBytes raw_device_tree);
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extern template ErrorOr<u64> slow_get_property(StringView name, FlattenedDeviceTreeHeader const& header, ReadonlyBytes raw_device_tree);
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extern template ErrorOr<StringView> slow_get_property(StringView name, FlattenedDeviceTreeHeader const& header, ReadonlyBytes raw_device_tree);
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} // namespace DeviceTree
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