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i2cset.c

/*
    i2cset.c - A user-space program to write an I2C register.
    Copyright (C) 2001-2003  Frodo Looijaard <frodol@dds.nl>, and
                             Mark D. Studebaker <mdsxyz123@yahoo.com>
    Copyright (C) 2004-2008  Jean Delvare <khali@linux-fr.org>

    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., 51 Franklin Street, Fifth Floor, Boston,
    MA 02110-1301 USA.
*/

#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/i2c-dev.h>
#include "i2cbusses.h"
#include "util.h"
#include "../version.h"

static void help(void) __attribute__ ((noreturn));

static void help(void)
{
      fprintf(stderr,
              "Usage: i2cset [-f] [-y] [-m MASK] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE [MODE]]\n"
            "  I2CBUS is an integer or an I2C bus name\n"
            "  ADDRESS is an integer (0x03 - 0x77)\n"
            "  MODE is one of:\n"
            "    b (byte, default)\n"
            "    w (word)\n"
            "    Append p for SMBus PEC\n");
      exit(1);
}

static int check_funcs(int file, int size, int pec)
{
      unsigned long funcs;

      /* check adapter functionality */
      if (ioctl(file, I2C_FUNCS, &funcs) < 0) {
            fprintf(stderr, "Error: Could not get the adapter "
                  "functionality matrix: %s\n", strerror(errno));
            return -1;
      }

      switch (size) {
      case I2C_SMBUS_BYTE:
            if (!(funcs & I2C_FUNC_SMBUS_WRITE_BYTE)) {
                  fprintf(stderr, MISSING_FUNC_FMT, "SMBus send byte");
                  return -1;
            }
            break;

      case I2C_SMBUS_BYTE_DATA:
            if (!(funcs & I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
                  fprintf(stderr, MISSING_FUNC_FMT, "SMBus write byte");
                  return -1;
            }
            break;

      case I2C_SMBUS_WORD_DATA:
            if (!(funcs & I2C_FUNC_SMBUS_WRITE_WORD_DATA)) {
                  fprintf(stderr, MISSING_FUNC_FMT, "SMBus write word");
                  return -1;
            }
            break;
      }

      if (pec
       && !(funcs & (I2C_FUNC_SMBUS_PEC | I2C_FUNC_I2C))) {
            fprintf(stderr, "Warning: Adapter does "
                  "not seem to support PEC\n");
      }

      return 0;
}

static int confirm(const char *filename, int address, int size, int daddress,
               int value, int vmask, int pec)
{
      int dont = 0;

      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\nmay render your "
                  "memory USELESS and make your system "
                  "UNBOOTABLE!\n");
            dont++;
      }

      fprintf(stderr, "I will write to device file %s, chip address "
            "0x%02x, data address\n0x%02x, ", filename, address, daddress);
      if (size == I2C_SMBUS_BYTE)
            fprintf(stderr, "no data.\n");
      else
            fprintf(stderr, "data 0x%02x%s, mode %s.\n", value,
                  vmask ? " (masked)" : "",
                  size == I2C_SMBUS_BYTE_DATA ? "byte" : "word");
      if (pec)
            fprintf(stderr, "PEC checking enabled.\n");

      fprintf(stderr, "Continue? [%s] ", dont ? "y/N" : "Y/n");
      fflush(stderr);
      if (!user_ack(!dont)) {
            fprintf(stderr, "Aborting on user request.\n");
            return 0;
      }

      return 1;
}

int main(int argc, char *argv[])
{
      char *end;
      const char *maskp = NULL;
      int res, i2cbus, address, size, file;
      int value, daddress, vmask = 0;
      char filename[20];
      int pec = 0;
      int flags = 0;
      int force = 0, yes = 0, version = 0, readback = 0;

      /* handle (optional) flags first */
      while (1+flags < argc && argv[1+flags][0] == '-') {
            switch (argv[1+flags][1]) {
            case 'V': version = 1; break;
            case 'f': force = 1; break;
            case 'y': yes = 1; break;
            case 'm':
                  if (2+flags < argc)
                        maskp = argv[2+flags];
                  flags++;
                  break;
            case 'r': readback = 1; break;
            default:
                  fprintf(stderr, "Error: Unsupported option "
                        "\"%s\"!\n", argv[1+flags]);
                  help();
                  exit(1);
            }
            flags++;
      }

      if (version) {
            fprintf(stderr, "i2cset version %s\n", VERSION);
            exit(0);
      }

      if (argc < flags + 4)
            help();

      i2cbus = lookup_i2c_bus(argv[flags+1]);
      if (i2cbus < 0)
            help();

      address = parse_i2c_address(argv[flags+2]);
      if (address < 0)
            help();

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

      if (argc > flags + 4) {
            size = I2C_SMBUS_BYTE_DATA;
            value = strtol(argv[flags+4], &end, 0);
            if (*end || value < 0) {
                  fprintf(stderr, "Error: Data value invalid!\n");
                  help();
            }
      } else {
            size = I2C_SMBUS_BYTE;
            value = -1;
      }

      if (argc > flags + 5) {
            switch (argv[flags+5][0]) {
            case 'b': size = I2C_SMBUS_BYTE_DATA; break;
            case 'w': size = I2C_SMBUS_WORD_DATA; break;
            default:
                  fprintf(stderr, "Error: Invalid mode!\n");
                  help();
            }
            pec = argv[flags+5][1] == 'p';
      }

      /* Old method to provide the value mask, deprecated and no longer
         documented but still supported for compatibility */
      if (argc > flags + 6) {
            if (maskp) {
                  fprintf(stderr, "Error: Data value mask provided twice!\n");
                  help();
            }
            fprintf(stderr, "Warning: Using deprecated way to set the data value mask!\n");
            fprintf(stderr, "         Please switch to using -m.\n");
            maskp = argv[flags+6];
      }

      if (maskp) {
            vmask = strtol(maskp, &end, 0);
            if (*end || vmask == 0) {
                  fprintf(stderr, "Error: Data value mask invalid!\n");
                  help();
            }
      }

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

      file = open_i2c_dev(i2cbus, filename, 0);
      if (file < 0
       || check_funcs(file, size, pec)
       || set_slave_addr(file, address, force))
            exit(1);

      if (!yes && !confirm(filename, address, size, daddress,
                       value, vmask, pec))
            exit(0);

      if (vmask) {
            int oldvalue;

            switch (size) {
            case I2C_SMBUS_BYTE:
                  oldvalue = i2c_smbus_read_byte(file);
                  break;
            case I2C_SMBUS_WORD_DATA:
                  oldvalue = i2c_smbus_read_word_data(file, daddress);
                  break;
            default:
                  oldvalue = i2c_smbus_read_byte_data(file, daddress);
            }

            if (oldvalue < 0) {
                  fprintf(stderr, "Error: Failed to read old value\n");
                  exit(1);
            }

            value = (value & vmask) | (oldvalue & ~vmask);

            if (!yes) {
                  fprintf(stderr, "Old value 0x%0*x, write mask "
                        "0x%0*x: Will write 0x%0*x to register "
                        "0x%02x\n",
                        size == I2C_SMBUS_WORD_DATA ? 4 : 2, oldvalue,
                        size == I2C_SMBUS_WORD_DATA ? 4 : 2, vmask,
                        size == I2C_SMBUS_WORD_DATA ? 4 : 2, value,
                        daddress);

                  fprintf(stderr, "Continue? [Y/n] ");
                  fflush(stderr);
                  if (!user_ack(1)) {
                        fprintf(stderr, "Aborting on user request.\n");
                        exit(0);
                  }
            }
      }

      if (pec && ioctl(file, I2C_PEC, 1) < 0) {
            fprintf(stderr, "Error: Could not set PEC: %s\n",
                  strerror(errno));
            close(file);
            exit(1);
      }

      switch (size) {
      case I2C_SMBUS_BYTE:
            res = i2c_smbus_write_byte(file, daddress);
            break;
      case I2C_SMBUS_WORD_DATA:
            res = i2c_smbus_write_word_data(file, daddress, value);
            break;
      default: /* I2C_SMBUS_BYTE_DATA */
            res = i2c_smbus_write_byte_data(file, daddress, value);
      }
      if (res < 0) {
            fprintf(stderr, "Error: Write failed\n");
            close(file);
            exit(1);
      }

      if (pec) {
            if (ioctl(file, I2C_PEC, 0) < 0) {
                  fprintf(stderr, "Error: Could not clear PEC: %s\n",
                        strerror(errno));
                  close(file);
                  exit(1);
            }
      }

      if (!readback) { /* We're done */
            close(file);
            exit(0);
      }

      switch (size) {
      case I2C_SMBUS_BYTE:
            res = i2c_smbus_read_byte(file);
            value = daddress;
            break;
      case I2C_SMBUS_WORD_DATA:
            res = i2c_smbus_read_word_data(file, daddress);
            break;
      default: /* I2C_SMBUS_BYTE_DATA */
            res = i2c_smbus_read_byte_data(file, daddress);
      }
      close(file);

      if (res < 0) {
            printf("Warning - readback failed\n");
      } else
      if (res != value) {
            printf("Warning - data mismatch - wrote "
                   "0x%0*x, read back 0x%0*x\n",
                   size == I2C_SMBUS_WORD_DATA ? 4 : 2, value,
                   size == I2C_SMBUS_WORD_DATA ? 4 : 2, res);
      } else {
            printf("Value 0x%0*x written, readback matched\n",
                   size == I2C_SMBUS_WORD_DATA ? 4 : 2, value);
      }

      exit(0);
}

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