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

/* Suche nach I2C-Adressen */
void scan_i2c_bus(int device)
  {
  int port, res;

  for (port = 0; port < 127; port++)
    {
    if (ioctl(device, I2C_SLAVE, port) < 0)
      perror("ioctl() I2C_SLAVE failed\n");
    else
      {
      res = i2c_smbus_read_byte(device);
      if (res >= 0)
        printf("i2c chip found at: %x, val = %d\n", port, res);
      }
    }
  }


int main(void)
  {
  int device;
  unsigned long funcs;

  printf("Opening device...");
  if ((device = open("/dev/i2c-1", O_RDWR)) < 0)
    {
    perror("open() failed");
    exit (1);
    }
  printf(" OK\n");

  if (ioctl(device,I2C_FUNCS,&funcs) < 0)
    {
    perror("ioctl() I2C_FUNCS failed");
    exit (1);
    }

  if (funcs & I2C_FUNC_I2C)
    printf("I2C\n");
  if (funcs & (I2C_FUNC_SMBUS_BYTE))
    printf("I2C_FUNC_SMBUS_BYTE\n");

  scan_i2c_bus(device);

  return 0;
  }