2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2013 David Chisnall
7 * This software was developed by SRI International and the University of
8 * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
9 * ("CTSRD"), as part of the DARPA CRASH research programme.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 #include "input_buffer.hh"
48 * The dtb namespace contains code related to the generation of device tree
49 * blobs, the binary representation of flattened device trees. The abstract
50 * tree representation calls into this code to generate the output.
54 /** The token types in the DTB, as defined by ยง7.4.1 of the ePAPR
55 * specification. All of these values are written in big-endian format in the
61 * Marker indicating the start of a node in the tree. This is followed
62 * by the nul-terminated name. If a unit address is specified, then
63 * the name also contains the address, with an @ symbol between the end
64 * of the name and the start of the address.
66 * The name is then padded such that the next token begins on a 4-byte
67 * boundary. The node may contain properties, other nodes, both, or be
70 FDT_BEGIN_NODE = 0x00000001,
72 * Marker indicating the end of a node.
74 FDT_END_NODE = 0x00000002,
76 * The start of a property. This is followed by two 32-bit big-endian
77 * values. The first indicates the length of the property value, the
78 * second its index in the strings table. It is then followed by the
79 * property value, if the value is of non-zero length.
81 FDT_PROP = 0x00000003,
83 * Ignored token. May be used for padding inside DTB nodes.
87 * Marker indicating the end of the tree.
93 * Returns the token as a string. This is used for debugging and for printing
94 * human-friendly error messages about malformed DTB input.
96 inline const char *token_type_name(token_type t)
101 return "FDT_BEGIN_NODE";
103 return "FDT_END_NODE";
115 * Abstract class for writing a section of the output. We create one
116 * of these for each section that needs to be written. It is intended to build
117 * a temporary buffer of the output in memory and then write it to a file
118 * stream. The size can be returned after all of the data has been written
119 * into the internal buffer, so the sizes of the three tables can be calculated
120 * before storing them in the buffer.
125 * Writes a label into the output stream. This is only applicable for
126 * assembly output, where the labels become symbols that can be
127 * resolved at link time.
129 virtual void write_label(const std::string &name) = 0;
131 * Writes a comment into the output stream. Useful only when debugging
134 virtual void write_comment(const std::string &name) = 0;
136 * Writes a string. A nul terminator is implicitly added.
138 virtual void write_string(const std::string &name) = 0;
140 * Writes a single 8-bit value.
142 virtual void write_data(uint8_t) = 0;
144 * Writes a single 32-bit value. The value is written in big-endian
145 * format, but should be passed in the host's native endian.
147 virtual void write_data(uint32_t) = 0;
149 * Writes a single 64-bit value. The value is written in big-endian
150 * format, but should be passed in the host's native endian.
152 virtual void write_data(uint64_t) = 0;
154 * Writes the collected output to the specified file descriptor.
156 virtual void write_to_file(int fd) = 0;
158 * Returns the number of bytes.
160 virtual uint32_t size() = 0;
162 * Helper for writing tokens to the output stream. This writes a
163 * comment above the token describing its value, for easier debugging
166 inline void write_token(token_type t)
168 write_comment(token_type_name(t));
169 write_data((uint32_t)t);
172 * Helper function that writes a byte buffer to the output, one byte at
175 void write_data(byte_buffer b);
179 * Binary file writer. This class is responsible for writing the DTB output
180 * directly in blob format.
182 class binary_writer : public output_writer
185 * The internal buffer used to store the blob while it is being
191 * The binary format does not support labels, so this method
194 void write_label(const std::string &) override {}
196 * Comments are ignored by the binary writer.
198 void write_comment(const std::string&) override {}
199 void write_string(const std::string &name) override;
200 void write_data(uint8_t v) override;
201 void write_data(uint32_t v) override;
202 void write_data(uint64_t v) override;
203 void write_to_file(int fd) override;
204 uint32_t size() override;
207 * Assembly writer. This class is responsible for writing the output in an
208 * assembly format that is suitable for linking into a kernel, loader, and so
211 class asm_writer : public output_writer
214 * The internal buffer for temporary values. Note that this actually
215 * contains ASCII text, but it is a byte buffer so that we can just
216 * copy strings across as-is.
220 * The number of bytes written to the current line. This is used to
221 * allow line wrapping, where we aim to write four .byte directives to
222 * make the alignment clearer.
226 * The current number of bytes written. This is the number in binary
227 * format, not the number of bytes in the buffer.
229 uint32_t bytes_written;
232 * Writes a string directly to the output as-is. This is the function that
233 * performs the real output.
235 void write_string(const char *c);
237 * Write a string to the output.
239 void write_string(const std::string &c) override;
241 * Writes the string, starting on a new line.
243 void write_line(const char *c);
245 * Writes a byte in binary format. This will emit a single .byte
246 * directive, with up to four per line.
248 void write_byte(uint8_t b);
250 asm_writer() : byte_count(0), bytes_written(0) {}
251 void write_label(const std::string &name) override;
252 void write_comment(const std::string &name) override;
253 void write_data(uint8_t v) override;
254 void write_data(uint32_t v) override;
255 void write_data(uint64_t v) override;
256 void write_to_file(int fd) override;
257 uint32_t size() override;
261 * Class encapsulating the device tree blob header. This class stores all of
262 * the values found in the header and is responsible for writing them to the
268 * Magic value, used to validate that this really is a device tree
269 * blob. Should always be set to 0xd00dfeed.
273 * The total size of the blob, including header, reservations, strings
274 * table, and padding.
278 * The offset from the start of the blob of the struct table (i.e. the
279 * part of the blob containing the entire device tree).
281 uint32_t off_dt_struct;
283 * The offset from the start of the blob of the strings table.
285 uint32_t off_dt_strings;
287 * The offset of the reservation map from the start of the blob.
289 uint32_t off_mem_rsvmap;
291 * The version of the blob. This should always be 17.
295 * The earliest version of the DTB specification with which this blob
296 * is backwards compatible. This should always be 16.
298 uint32_t last_comp_version;
300 * The ID of the CPU where this boots.
302 uint32_t boot_cpuid_phys;
304 * The size of the strings table.
306 uint32_t size_dt_strings;
308 * The size of the struct table.
310 uint32_t size_dt_struct;
312 * Writes the entire header to the specified output buffer.
314 void write(output_writer &out);
316 * Reads the header from bits binary representation in a blob.
318 bool read_dtb(input_buffer &input);
320 * Default constructor. Initialises the values that have sensible
321 * defaults, leaves the others blank.
323 header() : magic(0xd00dfeed), version(17), last_comp_version(16),
324 boot_cpuid_phys(0) {}
328 * Class encapsulating the string table. FDT strings are stored in a string
329 * section. This maintains a map from strings to their offsets in the strings
332 * Note: We don't currently do suffix matching, which may save a small amount
337 * Map from strings to their offset.
339 std::map<std::string, uint32_t> string_offsets;
341 * The strings, in the order in which they should be written to the
342 * output. The order must be stable - adding another string must not
343 * change the offset of any that we have already referenced - and so we
344 * simply write the strings in the order that they are passed.
346 std::vector<std::string> strings;
348 * The current size of the strings section.
353 * Default constructor, creates an empty strings table.
355 string_table() : size(0) {}
357 * Adds a string to the table, returning the offset from the start
358 * where it will be written. If the string is already present, this
359 * will return its existing offset, otherwise it will return a new
362 uint32_t add_string(const std::string &str);
364 * Writes the strings table to the specified output.
366 void write(dtb::output_writer &writer);