NetBSD Raspberry Pi I2C IOCTL Sample

gpio_test.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#include <stdint.h>

/* POSIX headers */
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <dev/i2c/i2c_io.h>

int write_eeprom(int fd, uint16_t addr, uint8_t val);
int read_eeprom_rand(int fd, uint16_t addr, uint8_t * val);

int main()
{
   int i2cfd, i;
   uint8_t byte_read, byte_written = 0xAA;
   unsigned char read_val;
   i2c_ioctl_exec_t iie;
   
   
   i2cfd = open("/dev/iic1", O_RDWR);
   if(i2cfd == -1)
   {
      printf("File open for I2C bus failed! (%s)\n", strerror(errno));
      return EXIT_FAILURE;
   }


   for(i = 0; i < 512; i++)
   {
      /* For a fresh EEPROM, 0xFF should be the default value.
        Let's rewrite it! */
      if(write_eeprom(i2cfd, i, (uint8_t) 0xFF))
      {
         printf("I2C write failed! (%s) \n", strerror(errno));
         close(i2cfd);
         return EXIT_FAILURE;
      }

      usleep(50000); /* 10 times the maximum time for internal writes to
                      register according to AT24HC04B datasheet (5ms) */
   }


   for(i = 0; i < 512; i++)
   {
      if(read_eeprom_rand(i2cfd, i, &byte_read))
      {
         printf("I2C read failed! (%s) \n", strerror(errno));
         close(i2cfd);
         return EXIT_FAILURE;
      }
      else
      {
         printf("%d\t", byte_read);
      }
   }


   close(i2cfd);
   return EXIT_SUCCESS;
}

int write_eeprom(int fd, uint16_t addr, uint8_t val)
{

   i2c_ioctl_exec_t iie;
   uint8_t page, byte_no;

   page = ((addr & 0x0100) >> 8);
   byte_no = (addr & 0x00FF);

   printf("w: page: %X, byte_no: %X, value: %X\n", page, byte_no, val);

   iie.iie_op = I2C_OP_WRITE_WITH_STOP;
   iie.iie_addr = 0x50 | page; /* Default for ATMEL EEPROMs,
               A0 is used for addr of 256b page .*/

   iie.iie_cmd = &byte_no; /* Send the write byte address first. */
   iie.iie_cmdlen = 1;
   iie.iie_buf = &val;
   iie.iie_buflen = 1;


   return ioctl(fd, I2C_IOCTL_EXEC, &iie);

}

int read_eeprom_rand(int fd, uint16_t addr, uint8_t * val)
{

   i2c_ioctl_exec_t iie;
   uint8_t page, byte_no;

   page = ((addr & 0x0100) >> 8);
   byte_no = (addr & 0x00FF);
   //printf("r: page: %X, byte_no: %X\n", page, byte_no);

   iie.iie_op = I2C_OP_READ_WITH_STOP;
   iie.iie_addr = 0x50 | page; /* Default for ATMEL EEPROMs,
               A0 is used for addr of 256b page .*/
   iie.iie_cmd = &byte_no; /* To do a random read, we need to send the
               byte address first. */
   iie.iie_cmdlen = 1;
   iie.iie_buf = val;
   iie.iie_buflen = 1;


   return ioctl(fd, I2C_IOCTL_EXEC, &iie);

}

Makefile

CFLAGS=
CPPFLAGS=
LDFLAGS=
LIBS=
LIBPATH=
RM=rm
RMFLAGS=-f
INSTALL=install


gpio_test: gpio_test.c
#       $(CC) $(LDFLAGS) $(LIBPATH) -o $@ $(GPIOBJS) $(LIBS)

.c:
        $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(LIBPATH) -o $@ $< $(LIBS)

.c.o:
        $(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<

clean:
        $(RM) $(RMFLAGS) *.o gpio_test