i2cscan.c

/*
 * i2cscan  FreeBSD version of i2cdetect
 *          Compile with:
 *              cc i2cscan.c -o i2cscan
 *
 * Winston Smith <[email protected]>
 */

#include <sys/cdefs.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <unistd.h>
#include <dev/iicbus/iic.h>


/*
 * Scan for the specified slave by trying to read a byte
 */
int scan(int fd, int slave)
{
    uint8_t              buf[2] = { 0, 0 };
    uint16_t             offset = 0;
    struct iic_msg       msg[2];
    struct iic_rdwr_data rdwr;


    msg[0].slave = slave;
    msg[0].flags = !IIC_M_RD;
    msg[0].len = sizeof(offset);
    msg[0].buf = (uint8_t*)&offset;

    msg[1].slave = slave;
    msg[1].flags = IIC_M_RD;
    msg[1].len = sizeof(buf);
    msg[1].buf = buf;


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

    if (ioctl(fd, I2CRDWR, &rdwr) < 0) {
        switch (errno) {
        case ENXIO:
            // Doesn't exist
            return 1;
        case EBUSY:
            // Currently in use
            return 2;
        default:
            perror("ioctl(I2CRDWR) failed");
            return -1;
        }
    }

    return 0;
}

int main(int argc, char **argv)
{
    int c, r, fd;
    char* dev = "/dev/iic0";

    if (argc > 1) {
        dev = argv[1];
    }

    if ((fd = open(dev, O_RDWR)) < 0 )  {
        perror("open failed");
        exit(-1);
    }

    printf("Checking device: %s\n", dev);
    printf("     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f\n");

    for (r = 0; r < 8; r++) {
        printf("%02X:", r*16);
        for (c = 0; c < 16; c++) {

            int addr = (r * 16) + c;

            switch (scan(fd, addr)) {
            case 0:
                printf(" %02X", addr);
                break;
            case 1:
                printf(" --");
                break;
            case 2:
                printf(" UU");
                break;
            default:
                break;
            }
        }
        printf("\n");
    }

    close(fd);
    exit(0);
}