Program derived from AR5k posted some time ago to overwrite regional domain code set in Atheros adapters, and repurposed to modify EEPROM addresses. Found at dagarlas.org. Thanks, Mr. Davide!

idchanger.c

/*
* This program is derived from code bearing the following Copyright(s)

/*                                                        -*- linux-c -*-
*   _  _ ____ __ _ ___ ____ ____ __ _ _ _ _ |
* .  \/  |--| | \|  |  |--< [__] | \| | _X_ | s e c u r e  s y s t e m s
*
* .vt|ar5k - PCI/CardBus 802.11a WirelessLAN driver for Atheros AR5k chipsets
*
* Copyright (c) 2002, .vantronix | secure systems
*                     and Reyk Floeter <reyk@va...>
*
* This program is free software ; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation ; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY ; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program ; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*
* Modified by Garlaschini Davide to allow changing ids
*
* --
* Salvaged from Wayback Machine-preserved blog
* "Workaround for HP notebooks with bios minipci lock" at dagarlas.org
*
* Donate to the Wayback Machine if you can! :)
* --
*/

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

#define AR5K_PCICFG 0x4010
#define AR5K_PCICFG_EEAE 0x00000001
#define AR5K_PCICFG_CLKRUNEN 0x00000004
#define AR5K_PCICFG_LED_PEND 0x00000020
#define AR5K_PCICFG_LED_ACT 0x00000040
#define AR5K_PCICFG_SL_INTEN 0x00000800
#define AR5K_PCICFG_BCTL 0x00001000
#define AR5K_PCICFG_SPWR_DN 0x00010000

/* EEPROM Registers in the MAC */
#define AR5211_EEPROM_ADDR 0x6000
#define AR5211_EEPROM_DATA 0x6004
#define AR5211_EEPROM_COMD 0x6008
#define AR5211_EEPROM_COMD_READ 0x0001
#define AR5211_EEPROM_COMD_WRITE 0x0002
#define AR5211_EEPROM_COMD_RESET 0x0003
#define AR5211_EEPROM_STATUS 0x600C
#define AR5211_EEPROM_STAT_RDERR 0x0001
#define AR5211_EEPROM_STAT_RDDONE 0x0002
#define AR5211_EEPROM_STAT_WRERR 0x0003
#define AR5211_EEPROM_STAT_WRDONE 0x0004
#define AR5211_EEPROM_CONF 0x6010

#define VT_WLAN_IN32(a) (*((volatile unsigned long int *)(mem + (a))))
#define VT_WLAN_OUT32(v, a) (*((volatile unsigned long int *)(mem + (a))) = (v))

#define ATHEROS_PCI_MEM_SIZE 0x10000

int vt_ar5211_eeprom_read(unsigned char *mem, unsigned long int offset,
                          unsigned short int *data) {
  int timeout = 10000;
  unsigned long int status;

  VT_WLAN_OUT32(0, AR5211_EEPROM_CONF), usleep(5);

  /** enable eeprom read access */
  VT_WLAN_OUT32(VT_WLAN_IN32(AR5211_EEPROM_COMD) | AR5211_EEPROM_COMD_RESET,
                AR5211_EEPROM_COMD);
  usleep(5);

  /** set address */
  VT_WLAN_OUT32((unsigned char)offset, AR5211_EEPROM_ADDR);
  usleep(5);

  VT_WLAN_OUT32(VT_WLAN_IN32(AR5211_EEPROM_COMD) | AR5211_EEPROM_COMD_READ,
                AR5211_EEPROM_COMD);

  while (timeout > 0) {
    usleep(1);
    status = VT_WLAN_IN32(AR5211_EEPROM_STATUS);
    if (status & AR5211_EEPROM_STAT_RDDONE) {
      if (status & AR5211_EEPROM_STAT_RDERR) {
        (void)fputs("eeprom read access failed!\n", stderr);
        return 1;
      }
      status = VT_WLAN_IN32(AR5211_EEPROM_DATA);
      *data = status & 0x0000ffff;
      return 0;
    }
    timeout--;
  }

  (void)fputs("eeprom read timeout!\n", stderr);

  return 1;
}

int vt_ar5211_eeprom_write(unsigned char *mem, unsigned int offset,
                           unsigned short int new_data) {
  int timeout = 10000;
  unsigned long int status;
  unsigned long int pcicfg;
  int i;
  unsigned short int sdata;

  /** enable eeprom access */
  pcicfg = VT_WLAN_IN32(AR5K_PCICFG);
  VT_WLAN_OUT32((pcicfg & ~AR5K_PCICFG_SPWR_DN), AR5K_PCICFG);
  usleep(500);
  VT_WLAN_OUT32(pcicfg | AR5K_PCICFG_EEAE /* | 0x2 */, AR5K_PCICFG);
  usleep(50);

  VT_WLAN_OUT32(0, AR5211_EEPROM_STATUS);
  usleep(50);

  /* VT_WLAN_OUT32( 0x1, AR5211_EEPROM_CONF ) ; */
  VT_WLAN_OUT32(0x0, AR5211_EEPROM_CONF);
  usleep(50);

  i = 100;
retry:
  /** enable eeprom write access */
  VT_WLAN_OUT32(AR5211_EEPROM_COMD_RESET, AR5211_EEPROM_COMD);
  usleep(500);

  /* Write data */
  VT_WLAN_OUT32(new_data, AR5211_EEPROM_DATA);
  usleep(5);

  /** set address */
  VT_WLAN_OUT32(offset, AR5211_EEPROM_ADDR);
  usleep(5);

  VT_WLAN_OUT32(AR5211_EEPROM_COMD_WRITE, AR5211_EEPROM_COMD);
  usleep(5);

  for (timeout = 10000; timeout > 0; --timeout) {
    status = VT_WLAN_IN32(AR5211_EEPROM_STATUS);
    if (status & 0xC) {
      if (status & AR5211_EEPROM_STAT_WRERR) {
        fprintf(stderr, "eeprom write access failed!\n");
        return 1;
      }
      VT_WLAN_OUT32(0, AR5211_EEPROM_STATUS);
      usleep(10);
      break;
    }
    usleep(10);
    timeout--;
  }
  (void)vt_ar5211_eeprom_read(mem, offset, &sdata);
  if ((sdata != new_data) && i) {
    --i;
    fprintf(stderr, "Retrying eeprom write!\n");
    goto retry;
  }

  return !i;
}

static void Usage() {
  (void)fprintf(
      stderr, "Usage: idchanger {-r|-w} physical_address_base [new_VendorID "
              "new_DevID new_Subs1 new_Subs2]\nphysical_address_base is a 32 "
              "bit hex value: 0xXXXXXXXX\nids are 16 bit hex values: 0xXXXX\n");
  return;
}

int main(int argc, char **argv) {
  unsigned long int base_addr;
  int fd;
  void *membase;
  unsigned short int sdata;
  unsigned short int new_id[4];

  if (argc < 2) {
    Usage();
    return -1;
  }

  if (strcmp(argv[1], "-r") == 0) {

    if (argc < 3) {
      printf("Using read command you have to specify adapter's "
             "physical_address_base\n");
      Usage();
      return -1;
    }

    base_addr = strtoul(argv[2], NULL, 0);
    fd = open("/dev/mem", O_RDWR);
    if (fd < 0) {
      fprintf(stderr, "Open of /dev/mem failed!\n");
      return -2;
    }
    membase = mmap(0, ATHEROS_PCI_MEM_SIZE, PROT_READ | PROT_WRITE,
                   MAP_SHARED | MAP_FILE, fd, base_addr);
    if (membase == (void *)-1) {
      fprintf(stderr, "Mmap of device at 0x%08X for 0x%X bytes failed!\n",
              base_addr, ATHEROS_PCI_MEM_SIZE);
      return -3;
    }

    printf("Accessing adapter at 0x%08X\n", base_addr);

    // Print HEX Dump
    int i;
    for (i = 0x00; i <= 0xFF; i++) {
      printf("Reading %x ", i);

      if (vt_ar5211_eeprom_read((unsigned char *)membase, i, &sdata))
        fprintf(stderr, "EEPROM read failed\n");

      printf("current value 0x%04X\n", sdata);
    }

  } else if (strcmp(argv[1], "-w") == 0) {

    if (argc < 7) {
      printf("Using write command you have to specify the 4 new ids\n");
      Usage();
      return -1;
    }

    int v;
    for (v = 3; v <= 6; v++) {
      if (strtoul(argv[v], NULL, 0) > 0xFFFF) {
        (void)fputs("Error: New ID must be 16 bit or less\n", stderr);
        Usage(argv[0]);
        return -2;
      } else {
        new_id[v - 3] = (unsigned short int)strtoul(argv[v], NULL, 0);
      }
    }

    base_addr = strtoul(argv[2], NULL, 0);
    fd = open("/dev/mem", O_RDWR);
    if (fd < 0) {
      fprintf(stderr, "Open of /dev/mem failed!\n");
      return -2;
    }
    membase = mmap(0, ATHEROS_PCI_MEM_SIZE, PROT_READ | PROT_WRITE,
                   MAP_SHARED | MAP_FILE, fd, base_addr);
    if (membase == (void *)-1) {
      fprintf(stderr, "Mmap of device at 0x%08X for 0x%X bytes failed!\n",
              base_addr, ATHEROS_PCI_MEM_SIZE);
      return -3;
    }

    printf("Accessing adapter at 0x%08X\n", base_addr);

#if 0
			(void) vt_ar5211_eeprom_write( (unsigned char *) membase, AR5K_EEPROM_PROTECT_OFFSET, 0 ) ;
#endif /* #if 0 */

    // Modify DEVID

    if (vt_ar5211_eeprom_read((unsigned char *)membase, 0x00, &sdata))
      fprintf(stderr, "EEPROM read failed\n");

    printf("Current value 0x%04X will change to 0x%04X\n", sdata, new_id[0]);

    if (vt_ar5211_eeprom_write((unsigned char *)membase, 0x00, new_id[0]))
      fprintf(stderr, "EEPROM write failed\n");

    // Modify VENDOR_ID

    if (vt_ar5211_eeprom_read((unsigned char *)membase, 0x01, &sdata))
      fprintf(stderr, "EEPROM read failed\n");

    printf("Current value 0x%04X will change to 0x%04X\n", sdata, new_id[1]);

    if (vt_ar5211_eeprom_write((unsigned char *)membase, 0x01, new_id[1]))
      fprintf(stderr, "EEPROM write failed\n");

    // Modify SubsystemID 0x07

    if (vt_ar5211_eeprom_read((unsigned char *)membase, 0x07, &sdata))
      fprintf(stderr, "EEPROM read failed\n");

    printf("Current value 0x%04X will change to 0x%04X\n", sdata, new_id[2]);

    if (vt_ar5211_eeprom_write((unsigned char *)membase, 0x07, new_id[2]))
      fprintf(stderr, "EEPROM write failed\n");

    // Modify SubsystemID 0x08

    if (vt_ar5211_eeprom_read((unsigned char *)membase, 0x08, &sdata))
      fprintf(stderr, "EEPROM read failed\n");

    printf("Current value 0x%04X will change to 0x%04X\n", sdata, new_id[3]);

    if (vt_ar5211_eeprom_write((unsigned char *)membase, 0x08, new_id[3]))
      fprintf(stderr, "EEPROM write failed\n");

  } else {
    Usage(argv[0]);
    return -1;
  }

  return 0;
}