mirror of
https://github.com/raspberrypi/rpi-eeprom.git
synced 2026-01-20 21:13:36 +08:00
96 lines
3.3 KiB
Python
Executable File
96 lines
3.3 KiB
Python
Executable File
#!/usr/bin/python
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# rpi-eeprom-config
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# Utility for reading and writing the configuration file in the
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# Raspberry Pi4 bootloader EEPROM image.
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import argparse
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import struct
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import sys
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IMAGE_SIZE = 512 * 1024
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# Each section starts with a magic number followed by a 32 bit offset to the
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# next section (big-endian).
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# The number, order and size of the sections depends on the bootloader version
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# but the following mask can be used to test for section headers and skip
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# unknown data.
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MAGIC = 0x55aaf00f
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MAGIC_MASK = 0xfffff00f
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FILE_MAGIC = 0x55aaf11f # id for modifiable file, currently only bootconf.txt
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FILE_HDR_LEN = 20
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FILENAME_LEN = 12
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class BootloaderImage(object):
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def __init__(self, filename, output):
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self._filename = filename
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self._bytes = bytearray(open(filename, 'rb').read())
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self._out = None
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if output is not None:
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self._out = open(output, 'wb')
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if len(self._bytes) != IMAGE_SIZE:
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raise Exception("%s: Expected size %d bytes actual size %d bytes" %
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(filename, IMAGE_SIZE, len(self._bytes)))
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def find_config(self):
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offset = 0
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magic = 0
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while offset < IMAGE_SIZE:
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magic, length = struct.unpack_from('>LL', self._bytes, offset)
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if (magic & MAGIC_MASK) != MAGIC:
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raise Exception('EEPROM is corrupted')
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if magic == FILE_MAGIC: # Found a file
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name = self._bytes[offset + 8: offset + FILE_HDR_LEN]
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if name.decode('utf-8') == 'bootconf.txt':
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return (offset, length)
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offset += 4 + length
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offset += 8 - (offset % 8) # Pad
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raise Exception('Bootloader config not found')
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def write(self, new_config):
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hdr_offset, length = self.find_config()
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new_config_bytes = open(new_config, 'rb').read()
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new_len = len(new_config_bytes) + FILENAME_LEN + 4
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if new_len > length and new_len > 1024:
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raise Exception('Config is too large')
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if hdr_offset + len(new_config_bytes) + FILE_HDR_LEN > IMAGE_SIZE:
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raise Exception('EEPROM image size exceeded')
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struct.pack_into('>L', self._bytes, hdr_offset + 4, new_len)
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struct.pack_into(("%ds" % len(new_config_bytes)), self._bytes, hdr_offset + 4 + FILE_HDR_LEN, new_config_bytes)
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if self._out is not None:
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self._out.write(self._bytes)
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self._out.close()
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else:
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sys.stdout.write(self._bytes)
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def read(self):
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hdr_offset, length = self.find_config()
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offset = hdr_offset + 4 + FILE_HDR_LEN
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config_bytes = self._bytes[offset:offset+length-FILENAME_LEN-4]
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if self._out is not None:
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self._out.write(config_bytes)
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self._out.close()
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else:
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sys.stdout.write(config_bytes)
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def main():
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parser = argparse.ArgumentParser('RPI EEPROM config tool')
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parser.add_argument('--config', help='Filename of new bootloader config')
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parser.add_argument('--out', help='Filename for the EEPROM image with updated config')
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parser.add_argument('eeprom', help='EEPROM filename (pieeprom.bin)')
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args = parser.parse_args()
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image = BootloaderImage(args.eeprom, args.out)
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if args.config is not None:
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image.write(args.config)
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else:
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image.read()
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if __name__ == '__main__':
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main()
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