documentation: move spidev_fdx example to its own source file

Move sample source code to its own source file so that it can be used
easier and build-tested/check/maintained by anyone.

(Makefile changes are in a separate patch for all of Documentation/.)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 158 insertions, 0 deletions

diff --git a/Documentation/spi/spidev_fdx.c b/Documentation/spi/spidev_fdx.c
new file mode 100644
index 000000000000..fc354f760384
--- /dev/null
+++ b/Documentation/spi/spidev_fdx.c
@@ -0,0 +1,158 @@
+#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 = (__u64) buf;
+        xfer[0].len = 1;
+
+        xfer[1].rx_buf = (__u64) 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;
+}