lm-sensors/prog/dump/i2cset.c

/*
    i2cset.c - A user-space program to write an I2C register.
    Copyright (c) 2001  Frodo Looijaard <frodol@dds.nl>, and
    Mark D. Studebaker <mdsxyz123@yahoo.com>

    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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>

void help(void)
{
  FILE *fptr;
  char s[100];

  fprintf(stderr,"Syntax: i2cset I2CBUS CHIP-ADDRESS DATA-ADDRESS VALUE [MODE]\n");
  fprintf(stderr,"  MODE is 'b[yte]' or 'w[ord]' (default b)\n");
  fprintf(stderr,"  I2CBUS is an integer\n");
  if((fptr = fopen("/proc/bus/i2c", "r"))) {
    fprintf(stderr,"  Installed I2C busses:\n");
    while(fgets(s, 100, fptr))
      fprintf(stderr, "    %s", s);	
    fclose(fptr);
  }
  exit(1);
}

int main(int argc, char *argv[])
{
  char *end;
  int res,i2cbus,address,size,file;
  int value, daddress;
  int e1, e2, e3;
  char filename1[20];
  char filename2[20];
  char filename3[20];
  char *filename;
  long funcs;

  if (argc < 5)
    help();

  i2cbus = strtol(argv[1],&end,0);
  if (*end || (i2cbus < 0) || (i2cbus > 0x3f)) {
    fprintf(stderr,"Error: I2CBUS argument invalid!\n");
    help();
  }

  address = strtol(argv[2],&end,0);
  if (*end || (address < 0) || (address > 0x7f)) {
    fprintf(stderr,"Error: Chip address invalid!\n");
    help();
  }

  daddress = strtol(argv[3],&end,0);
  if (*end || (daddress < 0) || (daddress > 0xff)) {
    fprintf(stderr,"Error: Data address invalid!\n");
    help();
  }

  value = strtol(argv[4],&end,0);
  if (*end) {
    fprintf(stderr,"Error: Data value invalid!\n");
    help();
  }

  if (argc < 6) {
    fprintf(stderr,"Warning: no size specified (using byte-data access)\n");
    size = I2C_SMBUS_BYTE_DATA;
  } else if (!strcmp(argv[5],"b"))
    size = I2C_SMBUS_BYTE_DATA;
  else if (!strcmp(argv[5],"w"))
    size = I2C_SMBUS_WORD_DATA;
  else {
    fprintf(stderr,"Error: Invalid mode!\n");
    help();
  }

  if ((value < 0) || ((size == I2C_SMBUS_BYTE_DATA) && (value > 0xff))
		  || ((size == I2C_SMBUS_WORD_DATA) && (value > 0x0ffff))) {
    fprintf(stderr,"Error: Data value out of range!\n");
    help();
  }

/*
 * Try all three variants and give the correct error message
 * upon failure
 */

  sprintf(filename1,"/dev/i2c-%d",i2cbus);
  sprintf(filename2,"/dev/i2c%d",i2cbus);
  sprintf(filename3,"/dev/i2c/%d",i2cbus);
  if ((file = open(filename1,O_RDWR)) < 0) {
    e1 = errno;
    if ((file = open(filename2,O_RDWR)) < 0) {
      e2 = errno;
      if ((file = open(filename3,O_RDWR)) < 0) {
        e3 = errno;
        if(e1 == ENOENT && e2 == ENOENT && e3 == ENOENT) {
          fprintf(stderr,"Error: Could not open file `%s', `%s', or `%s': %s\n",
                     filename1,filename2,filename3,strerror(ENOENT));
        }
        if (e1 != ENOENT) {
          fprintf(stderr,"Error: Could not open file `%s' : %s\n",
                     filename1,strerror(e1));
          if(e1 == EACCES)
            fprintf(stderr,"Run as root?\n");
        }
        if (e2 != ENOENT) {
          fprintf(stderr,"Error: Could not open file `%s' : %s\n",
                     filename2,strerror(e2));
          if(e2 == EACCES)
            fprintf(stderr,"Run as root?\n");
        }
        if (e3 != ENOENT) {
          fprintf(stderr,"Error: Could not open file `%s' : %s\n",
                     filename3,strerror(e3));
          if(e3 == EACCES)
            fprintf(stderr,"Run as root?\n");
        }
        exit(1);
      } else {
         filename = filename3;
      }
    } else {
       filename = filename2;
    }
  } else {
    filename = filename1;
  }
  
  /* check adapter functionality */
  if (ioctl(file,I2C_FUNCS,&funcs) < 0) {
    fprintf(stderr,
            "Error: Could not get the adapter functionality matrix: %s\n",
            strerror(errno));
    exit(1);
  }

  switch(size) {
     case I2C_SMBUS_BYTE_DATA:
	if (! (funcs &
	    (I2C_FUNC_SMBUS_WRITE_BYTE_DATA | I2C_FUNC_SMBUS_READ_BYTE_DATA))) {
	   fprintf(stderr, "Error: Adapter for i2c bus %d", i2cbus);
	   fprintf(stderr, " does not have byte write capability\n");
	   exit(1);
	}       
	break;

     case I2C_SMBUS_WORD_DATA:
	if (! (funcs &
	    (I2C_FUNC_SMBUS_WRITE_WORD_DATA | I2C_FUNC_SMBUS_READ_WORD_DATA))) {
	   fprintf(stderr, "Error: Adapter for i2c bus %d", i2cbus);
	   fprintf(stderr, " does not have word write capability\n");
	   exit(1);
	}       
	break;

  }
  /* use FORCE so that we can write registers even when
     a driver is also running */
  if (ioctl(file,I2C_SLAVE_FORCE,address) < 0) {
    fprintf(stderr,"Error: Could not set address to %d: %s\n",address,
            strerror(errno));
    exit(1);
  }
 
  fprintf(stderr,"  WARNING! This program can confuse your I2C bus, "
          "cause data loss and worse!\n");
  if(address >= 0x50 && address <= 0x57) {
	fprintf(stderr, "DANGEROUS!! Writing to a serial EEPROM on a memory DIMM\n");
	fprintf(stderr, "may render your memory USELESS and make your system UNBOOTABLE!!!\n");
	fprintf(stderr, "Are you SURE that you want to write to the chip at address 0x%.2x? (n) ", address);
	res = getchar();
	if(res != 'y' && res != 'Y')
		exit(1);
  }	
  fprintf(stderr,"  I will write device file %s, chip address 0x%.2x, data address 0x%.2x, data 0x%x, mode %s\n",
          filename, address, daddress, value,
                           size == I2C_SMBUS_BYTE_DATA ? "byte" : "word");
  fprintf(stderr,"  You have five seconds to reconsider and press CTRL-C!\n\n");
  sleep(5);

  e1 = 0;
  if (size == I2C_SMBUS_WORD_DATA) {
	res = i2c_smbus_write_word_data(file, daddress, value);
  } else {
	res = i2c_smbus_write_byte_data(file, daddress, value);
  }
  if(res < 0) {
	fprintf(stderr, "Warning - write failed\n");
	e1++;
  }
  if (size == I2C_SMBUS_WORD_DATA) {
	res = i2c_smbus_read_word_data(file, daddress);
  } else {
	res = i2c_smbus_read_byte_data(file, daddress);
  }
  if(res < 0) {
	fprintf(stderr, "Warning - readback failed\n");
	e1++;
  } else {
	if(res != value) {
		e1++;
		if (size == I2C_SMBUS_WORD_DATA)
			fprintf(stderr, "Warning - data mismatch - wrote 0x%.4x, read back 0x%.4x\n", value, res);
		else
			fprintf(stderr, "Warning - data mismatch - wrote 0x%.2x, read back 0x%.2x\n", value, res);
	} else {
		fprintf(stderr, "Value 0x%x written, readback matched\n", value);
	}
  }     
  exit(e1);
}