5da98448d8
JSON is a rather more free format than devicetree, so it is sometimes better to parse it into dtb format. This is widely used in U-Boot and we can use the ofnode interface to access it. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>
58 lines
2.0 KiB
C
58 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* JSON utilities
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*
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* Copyright (C) 2025 Canonical Ltd
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* Written by Simon Glass <simon.glass@canonical.com>
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*/
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#ifndef __JSON_H__
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#define __JSON_H__
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struct abuf;
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/**
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* json_print_pretty() - Print JSON with indentation
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*
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* This function takes a JSON string and prints it with proper indentation,
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* making it more human-readable. It handles nested objects and arrays.
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*
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* @json: JSON string to print (may be nul terminated before @len)
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* @len: Length of JSON string
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*/
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void json_print_pretty(const char *json, int len);
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/**
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* json_to_fdt() - Convert JSON to a Flattened Device Tree (DTB) blob
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*
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* Parse a JSON string and convert it to a dtb blob. JSON objects become nodes;
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* JSON properties become device tree properties. This is useful for converting
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* LUKS2 metadata to a format that can be queried using U-Boot's ofnode APIs.
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*
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* This function temporarily modifies the JSON string in-place, writing nul
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* terminators during parsing, then restores the original characters. The JSON
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* string is only modified during the function call and is restored before
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* returning.
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*
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* The resulting DTB contains copies of all data, so the JSON string can be
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* freed or modified after this function returns.
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*
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* Conversion rules:
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* - JSON objects → DT nodes
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* - JSON strings → string properties
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* - JSON numbers → u32 or u64 cell properties
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* - JSON arrays of numbers → cell array properties (max MAX_ARRAY_SIZE)
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* - JSON arrays of strings → stringlist properties (max MAX_ARRAY_SIZE)
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* - JSON booleans → u32 properties (0 or 1). This breaks the dtb convention of
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* simply using presence to indicate true, so that we can actually check
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* what was present in the JSON data
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* - JSON null → empty property
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*
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* @json: JSON string to parse (temporarily modified during call)
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* @buf: abuf to init and populate with the DTB (called must uninit)
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* Return: 0 on success, negative error code on failure
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*/
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int json_to_fdt(const char *json, struct abuf *buf);
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#endif /* __JSON_H__ */
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