LXR linux/Documentation/spi/spidev

   1#include <stdio.h>
   2#include <unistd.h>
   3#include <stdlib.h>
   4#include <fcntl.h>
   5#include <string.h>
   6
   7#include <sys/ioctl.h>
   8#include <sys/types.h>
   9#include <sys/stat.h>
  10
  11#include <linux/types.h>
  12#include <linux/spi/spidev.h>
  13
  14
  15static int verbose;
  16
  17static void do_read(int fd, int len)
  18{
  19        unsigned char   buf[32], *bp;
  20        int             status;
  21
  22        /* read at least 2 bytes, no more than 32 */
  23        if (len < 2)
  24                len = 2;
  25        else if (len > sizeof(buf))
  26                len = sizeof(buf);
  27        memset(buf, 0, sizeof buf);
  28
  29        status = read(fd, buf, len);
  30        if (status < 0) {
  31                perror("read");
  32                return;
  33        }
  34        if (status != len) {
  35                fprintf(stderr, "short read\n");
  36                return;
  37        }
  38
  39        printf("read(%2d, %2d): %02x %02x,", len, status,
  40                buf[0], buf[1]);
  41        status -= 2;
  42        bp = buf + 2;
  43        while (status-- > 0)
  44                printf(" %02x", *bp++);
  45        printf("\n");
  46}
  47
  48static void do_msg(int fd, int len)
  49{
  50        struct spi_ioc_transfer xfer[2];
  51        unsigned char           buf[32], *bp;
  52        int                     status;
  53
  54        memset(xfer, 0, sizeof xfer);
  55        memset(buf, 0, sizeof buf);
  56
  57        if (len > sizeof buf)
  58                len = sizeof buf;
  59
  60        buf[0] = 0xaa;
  61        xfer[0].tx_buf = (__u64) buf;
  62        xfer[0].len = 1;
  63
  64        xfer[1].rx_buf = (__u64) buf;
  65        xfer[1].len = len;
  66
  67        status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer);
  68        if (status < 0) {
  69                perror("SPI_IOC_MESSAGE");
  70                return;
  71        }
  72
  73        printf("response(%2d, %2d): ", len, status);
  74        for (bp = buf; len; len--)
  75                printf(" %02x", *bp++);
  76        printf("\n");
  77}
  78
  79static void dumpstat(const char *name, int fd)
  80{
  81        __u8    mode, lsb, bits;
  82        __u32   speed;
  83
  84        if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) {
  85                perror("SPI rd_mode");
  86                return;
  87        }
  88        if (ioctl(fd, SPI_IOC_RD_LSB_FIRST, &lsb) < 0) {
  89                perror("SPI rd_lsb_fist");
  90                return;
  91        }
  92        if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) < 0) {
  93                perror("SPI bits_per_word");
  94                return;
  95        }
  96        if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) < 0) {
  97                perror("SPI max_speed_hz");
  98                return;
  99        }
 100
 101        printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n",
 102                name, mode, bits, lsb ? "(lsb first) " : "", speed);
 103}
 104
 105int main(int argc, char **argv)
 106{
 107        int             c;
 108        int             readcount = 0;
 109        int             msglen = 0;
 110        int             fd;
 111        const char      *name;
 112
 113        while ((c = getopt(argc, argv, "hm:r:v")) != EOF) {
 114                switch (c) {
 115                case 'm':
 116                        msglen = atoi(optarg);
 117                        if (msglen < 0)
 118                                goto usage;
 119                        continue;
 120                case 'r':
 121                        readcount = atoi(optarg);
 122                        if (readcount < 0)
 123                                goto usage;
 124                        continue;
 125                case 'v':
 126                        verbose++;
 127                        continue;
 128                case 'h':
 129                case '?':
 130usage:
 131                        fprintf(stderr,
 132                                "usage: %s [-h] [-m N] [-r N] /dev/spidevB.D\n",
 133                                argv[0]);
 134                        return 1;
 135                }
 136        }
 137
 138        if ((optind + 1) != argc)
 139                goto usage;
 140        name = argv[optind];
 141
 142        fd = open(name, O_RDWR);
 143        if (fd < 0) {
 144                perror("open");
 145                return 1;
 146        }
 147
 148        dumpstat(name, fd);
 149
 150        if (msglen)
 151                do_msg(fd, msglen);
 152
 153        if (readcount)
 154                do_read(fd, readcount);
 155
 156        close(fd);
 157        return 0;
 158}
 159