Script for https://github.com/espressif/qemu/issues/76

gen_efuse.py

import argparse
import binascii
import sys


def main():
    parser = argparse.ArgumentParser(description="Generate efuse binary")
    parser.add_argument(
        "--mac", type=str, default="11:22:33:44:55:66", help="MAC address to use"
    )
    parser.add_argument("output_file", type=argparse.FileType("wb"), help="Output file")
    args = parser.parse_args()

    mac_addr_str = args.mac
    mac_addr = binascii.unhexlify(mac_addr_str.replace(":", ""))
    mac_addr_crc = calc_mac_addr_crc(mac_addr)

    efuse_data = bytearray(124)

    # MAC address
    efuse_data[4:10] = mac_addr[::-1]
    efuse_data[10] = mac_addr_crc

    # Chip revision bits
    efuse_data[13] = 0x80
    efuse_data[22] = 0x10

    args.output_file.write(efuse_data)


def calc_mac_addr_crc(mac_addr):
    i = 0
    j = 0
    crc = 0
    length = len(mac_addr)

    while length > 0:
        length -= 1
        crc = crc ^ mac_addr[j]
        j += 1

        for i in range(8):
            if (crc) & 0x01:
                crc = ((crc >> 1) ^ (0x8C)) & 0xFF
            else:
                crc = (crc >> 1) & 0xFF

    return crc


if __name__ == "__main__":
    sys.exit(main())