24c256 backup and restore

24c256br.c

/*

Utility to dump and restore a 24c256 eeprom.
(Changing the defines it will work with other eeproms too.)

Remember that 24c256 has 16 bit addressing.
Smaller ones have 8 bit addressing.

By Zibri.

Usage:  24c256br /dev/i2c-X >eep_dump.bin to dump.
        24c256br /dev/i2c-X <eep_dump.bin to restore.

*/

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>

#define READ_SIZE     (256)
#define NB_PAGES      (128)

#define WRITE_SIZE    (64)
#define WRITE_PAGES   (512)

int main(int argc, char *argv[])
{

  if ((isatty(0) && isatty(1)) || argc != 2) {
    dprintf(2, "Usage:\t%s /dev/i2c-X >eep_dump.bin to dump.\n\t%s /dev/i2c-X <eep_dump.bin to restore.\n", argv[0], argv[0]);
    return 1;
  }

  const int device_address = 0x50;

  int file = open(argv[1], O_RDWR);
  if (file < 0) {
    printf("Failed opening %s\n", argv[1]);
    return 1;
  }

  if (ioctl(file, I2C_SLAVE, device_address) < 0) {
    printf("Failed addressing device at %02X\n", device_address);
    close(file);
    return 1;
  }

  if (!isatty(1)) {             // if stdout is redirected then DUMP

    int i = 0;

    char buf[32768] = { 0 };

    write(file, buf, 2);        // set address to 0

    usleep(5000);

    for (i = 0; i < NB_PAGES; i++) {

      if (read(file, buf, READ_SIZE) != READ_SIZE) {
        dprintf(2, "Failed reading\n");
        close(file);
        return 1;
      }

      write(1, buf, READ_SIZE);

    }

  } else {                      // stdout is not redirected but stdin is so WRITE

    int i = 0;

    for (i = 0; i < WRITE_PAGES; i++) {
      char buf[WRITE_SIZE + 2] = { 0 };
      int isw = i * WRITE_SIZE;

      buf[0] = (isw >> 8) & 0xff;       // HI ADDR
      buf[1] = isw & 0xff;              // LO ADDR

      if (read(0, buf + 2, WRITE_SIZE) != WRITE_SIZE) {
        dprintf(2, "Failed reading\n");
        return 1;
      }

      write(file, buf, WRITE_SIZE + 2);

      int rdy = 0;

      do {                      // Acknowledge Polling :D
        rdy = write(file, buf, 2);
      } while (rdy != 2);

    }

  }

  close(file);

  return 0;

}