pi_i2c.c

Go to the documentation of this file.

#include "config.h"

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

#include "pihwm.h"
#include "pi_i2c.h"

int
i2c_init()
{
    int rev;

    if ( check_kernel_module("i2c_dev") < 0 )
    {
        debug("[%s] Kernel module \"i2c_dev\" not loaded.\n", __func__);
        return -1;
    }

    if ( check_kernel_module("i2c_bcm2708") < 0 )
    {
        debug("[%s] Kernel module \"i2c_bcm2708\" not loaded.\n", __func__);
        return -1;
    }

    rev = board_rev();

    if ( rev == REV_1 )
    {
        return i2c_init_name("/dev/i2c-0");
    }
    else if ( rev == REV_2 )
    {
        return i2c_init_name("/dev/i2c-1");
    }
    else
    {
        return -1;
    }

}

int
i2c_init_name (char *devname)
{
    int fd = open (devname, O_RDWR);

    if ( fd < 0 )
    {
        debug("[%s] Can't open %s : %s\n", __func__, devname, strerror (errno));
        return -1;
    }
    else
    {
        return fd;
    }
}

int
i2c_select_device (unsigned int fd, unsigned int addr)
{
    if ( ioctl (fd, I2C_SLAVE, addr) < 0 )
    {
        debug("[%s] Can't select device %s: %s\n", __func__, addr, strerror (errno));
        return -1;
    }
    else
    {
        return 1;
    }
}

int
i2c_write (unsigned int fd, unsigned int addr, unsigned char *data, unsigned int len)
{

    if ( i2c_select_device (fd, addr) )
    {
        if ( write (fd, data, len) != len )
        {
            debug("[%s] I2C write (address: 0x%X) failed: %s\n", __func__, addr, strerror (errno));
            return -1;
        }
    }
    else
    {
        printf ("[%s] Can't select I2C device at address: 0x%X, write failed\n", __func__, addr);
        return -1;
    }

    return 1;
}

int
i2c_read (unsigned int fd, unsigned int addr, unsigned char *data,  unsigned int len)
{
    char buf[len];

    if ( i2c_select_device (fd, addr) )
    {
        if ( read (fd, buf, len) != len )
        {
            debug("[%s]: I2C read (address: 0x%X) failed: %s\n", __func__, addr, strerror (errno));
            return -1;
        }
        else
        {
            memcpy(data, buf, len);
            return 1;
        }
    }
    else
    {
        debug("[%s] Can't select I2C device at address: 0x%X, write failed\n", __func__, addr);
        return -1;
    }
}


/*
* FIXME: Test this.
int
i2c_read_write (unsigned int fd, unsigned int addr, unsigned char *write, unsigned char *read)
{

    struct i2c_msg  msgs[2]; 
    struct i2c_rdwr_ioctl_data  rdwr; 
    int rc; 

    msgs[0].addr  = ADDR; 
    msgs[0].flags = 0; 
    msgs[0].buf   = write_buf;
    msgs[0].len   = count(write_buf);

    msgs[1].addr  = ADDR; 
    msgs[1].flags = I2C_M_RD; 
    msgs[1].buf   = read_buf; 
    msgs[1].len   = count(read_buf); 

    rdwr.msgs  = msgs; 
    rdwr.nmsgs = 2; 

    if ( i2c_select_device (fd, addr) ){
        // FIXME: add error checking here
        ioctl( fd , I2C_RDWR , &rdwr );
    } else {
        debug ("[%s] Can't select I2C device at address: 0x%X, read failed\n", __func__, addr);
        return -1;
    }

    return 1;
}
*/