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MelvinTo/watchdog_sample.c

Created April 2, 2017 15:30
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  1. MelvinTo created this gist Apr 2, 2017.
    160 changes: 160 additions & 0 deletions watchdog_sample.c
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    Original file line number Diff line number Diff line change
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    cat a.c
    /*
    * Linux watchdog demo for LPC313x
    *
    * This program is free software; you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation; either version 2 of the License, or
    * (at your option) any later version.
    *
    * This program is distributed in the hope that it will be useful,
    * but WITHOUT ANY WARRANTY; without even the implied warranty of
    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    * GNU General Public License for more details.
    *
    * You should have received a copy of the GNU General Public License
    * along with this program; if not, write to the Free Software
    * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    *
    */
    #include <stdio.h>
    #include <stdlib.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <getopt.h>
    #include <string.h>
    #include <errno.h>

    #include <linux/watchdog.h>

    #define WATCHDOGDEV "/dev/watchdog"
    static const char *const short_options = "hd:i:";
    static const struct option long_options[] = {
    {"help", 0, NULL, 'h'},
    {"dev", 1, NULL, 'd'},
    {"interval", 1, NULL, 'i'},
    {NULL, 0, NULL, 0},
    };

    static void print_usage(FILE * stream, char *app_name, int exit_code)
    {
    fprintf(stream, "Usage: %s [options]\n", app_name);
    fprintf(stream,
    " -h --help Display this usage information.\n"
    " -d --dev <device_file> Use <device_file> as watchdog device file.\n"
    " The default device file is '/dev/watchdog'\n"
    " -i --interval <interval> Change the watchdog interval time\n");

    exit(exit_code);
    }

    int main(int argc, char **argv)
    {
    int fd; /* File handler for watchdog */
    int interval; /* Watchdog timeout interval (in secs) */
    int bootstatus; /* Wathdog last boot status */
    char *dev; /* Watchdog default device file */

    int next_option; /* getopt iteration var */
    char kick_watchdog; /* kick_watchdog options */

    /* Init variables */
    dev = WATCHDOGDEV;
    interval = 0;
    kick_watchdog = 0;

    /* Parse options if any */
    do {
    next_option = getopt_long(argc, argv, short_options,
    long_options, NULL);
    switch (next_option) {
    case 'h':
    print_usage(stdout, argv[0], EXIT_SUCCESS);
    case 'd':
    dev = optarg;
    break;
    case 'i':
    interval = atoi(optarg);
    break;
    case '?': /* Invalid options */
    print_usage(stderr, argv[0], EXIT_FAILURE);
    case -1: /* Done with options */
    break;
    default: /* Unexpected stuffs */
    abort();
    }
    } while (next_option != -1);

    /* Once the watchdog device file is open, the watchdog will be activated by
    the driver */
    fd = open(dev, O_RDWR);
    if (-1 == fd) {
    fprintf(stderr, "Error: %s\n", strerror(errno));
    exit(EXIT_FAILURE);
    }

    /* If user wants to change the watchdog interval */
    if (interval != 0) {
    fprintf(stdout, "Set watchdog interval to %d\n", interval);
    if (ioctl(fd, WDIOC_SETTIMEOUT, &interval) != 0) {
    fprintf(stderr,
    "Error: Set watchdog interval failed\n");
    exit(EXIT_FAILURE);
    }
    }

    /* Display current watchdog interval */
    if (ioctl(fd, WDIOC_GETTIMEOUT, &interval) == 0) {
    fprintf(stdout, "Current watchdog interval is %d\n", interval);
    } else {
    fprintf(stderr, "Error: Cannot read watchdog interval\n");
    exit(EXIT_FAILURE);
    }

    /* Check if last boot is caused by watchdog */
    if (ioctl(fd, WDIOC_GETBOOTSTATUS, &bootstatus) == 0) {
    fprintf(stdout, "Last boot is caused by : %s\n",
    (bootstatus != 0) ? "Watchdog" : "Power-On-Reset");
    } else {
    fprintf(stderr, "Error: Cannot read watchdog status\n");
    exit(EXIT_FAILURE);
    }

    /* There are two ways to kick the watchdog:
    - by writing any dummy value into watchdog device file, or
    - by using IOCTL WDIOC_KEEPALIVE
    */
    fprintf(stdout,
    "Use:\n"
    " <w> to kick through writing over device file\n"
    " <i> to kick through IOCTL\n" " <x> to exit the program\n");
    do {
    kick_watchdog = getchar();
    switch (kick_watchdog) {
    case 'w':
    write(fd, "w", 1);
    fprintf(stdout,
    "Kick watchdog through writing over device file\n");
    break;
    case 'i':
    ioctl(fd, WDIOC_KEEPALIVE, NULL);
    fprintf(stdout, "Kick watchdog through IOCTL\n");
    break;
    case 'x':
    fprintf(stdout, "Goodbye !\n");
    break;
    default:
    fprintf(stdout, "Unknown command\n");
    break;
    }
    } while (kick_watchdog != 'x');

    /* The 'V' value needs to be written into watchdog device file to indicate
    that we intend to close/stop the watchdog. Otherwise, debug message
    'Watchdog timer closed unexpectedly' will be printed
    */
    write(fd, "V", 1);
    /* Closing the watchdog device will deactivate the watchdog. */
    close(fd);
    }