spidev_fdx.c

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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <linux/types.h>
#include <linux/spi/spidev.h>


static int verbose;

static void do_read(int fd, int len)
{
    unsigned char   buf[32], *bp;
    int     status;

    /* read at least 2 bytes, no more than 32 */
    if (len < 2)
        len = 2;
    else if (len > sizeof(buf))
        len = sizeof(buf);
    memset(buf, 0, sizeof buf);

    status = read(fd, buf, len);
    if (status < 0) {
        perror("read");
        return;
    }
    if (status != len) {
        fprintf(stderr, "short read\n");
        return;
    }

    printf("read(%2d, %2d): %02x %02x,", len, status,
        buf[0], buf[1]);
    status -= 2;
    bp = buf + 2;
    while (status-- > 0)
        printf(" %02x", *bp++);
    printf("\n");
}

static void do_msg(int fd, int len)
{
    struct spi_ioc_transfer xfer[2];
    unsigned char       buf[32], *bp;
    int         status;

    memset(xfer, 0, sizeof xfer);
    memset(buf, 0, sizeof buf);

    if (len > sizeof buf)
        len = sizeof buf;

    buf[0] = 0xaa;
    xfer[0].tx_buf = (unsigned long)buf;
    xfer[0].len = 1;

    xfer[1].rx_buf = (unsigned long) buf;
    xfer[1].len = len;

    status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer);
    if (status < 0) {
        perror("SPI_IOC_MESSAGE");
        return;
    }

    printf("response(%2d, %2d): ", len, status);
    for (bp = buf; len; len--)
        printf(" %02x", *bp++);
    printf("\n");
}

static void dumpstat(const char *name, int fd)
{
    __u8    mode, lsb, bits;
    __u32   speed;

    if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) {
        perror("SPI rd_mode");
        return;
    }
    if (ioctl(fd, SPI_IOC_RD_LSB_FIRST, &lsb) < 0) {
        perror("SPI rd_lsb_fist");
        return;
    }
    if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) < 0) {
        perror("SPI bits_per_word");
        return;
    }
    if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) < 0) {
        perror("SPI max_speed_hz");
        return;
    }

    printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n",
        name, mode, bits, lsb ? "(lsb first) " : "", speed);
}

int main(int argc, char **argv)
{
    int     c;
    int     readcount = 0;
    int     msglen = 0;
    int     fd;
    const char  *name;

    while ((c = getopt(argc, argv, "hm:r:v")) != EOF) {
        switch (c) {
        case 'm':
            msglen = atoi(optarg);
            if (msglen < 0)
                goto usage;
            continue;
        case 'r':
            readcount = atoi(optarg);
            if (readcount < 0)
                goto usage;
            continue;
        case 'v':
            verbose++;
            continue;
        case 'h':
        case '?':
usage:
            fprintf(stderr,
                "usage: %s [-h] [-m N] [-r N] /dev/spidevB.D\n",
                argv[0]);
            return 1;
        }
    }

    if ((optind + 1) != argc)
        goto usage;
    name = argv[optind];

    fd = open(name, O_RDWR);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    dumpstat(name, fd);

    if (msglen)
        do_msg(fd, msglen);

    if (readcount)
        do_read(fd, readcount);

    close(fd);
    return 0;
}