Documentation/spi/spidev_fdx.c

   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
  15 static int verbose;
  16
  17 static 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
  48 static 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
  79 static 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
 105 int 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 '?':
 130 usage:
 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 }