watchdog.c

   1 /*
   2  * Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
   3  * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/watchdog.h>
  16
  17 #include <sys/ioctl.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <fcntl.h>
  21
  22 #include <unistd.h>
  23
  24 #include <libubox/uloop.h>
  25
  26 #include "procd.h"
  27 #include "watchdog.h"
  28
  29 #define WDT_PATH        "/dev/watchdog"
  30
  31 static struct uloop_timeout wdt_timeout;
  32 static int wdt_fd = -1;
  33 static int wdt_frequency = 5;
  34
  35 static void watchdog_timeout_cb(struct uloop_timeout *t)
  36 {
  37         DEBUG(2, "Ping\n");
  38         if (write(wdt_fd, "X", 1) < 0)
  39                 ERROR("WDT failed to write: %s\n", strerror(errno));
  40         uloop_timeout_set(t, wdt_frequency * 1000);
  41 }
  42
  43 int watchdog_timeout(int timeout)
  44 {
  45         if (wdt_fd < 0)
  46                 return 0;
  47
  48         if (timeout) {
  49                 DEBUG(2, "Set watchdog timeout: %ds\n", timeout);
  50                 ioctl(wdt_fd, WDIOC_SETTIMEOUT, &timeout);
  51         }
  52         ioctl(wdt_fd, WDIOC_GETTIMEOUT, &timeout);
  53
  54         return timeout;
  55 }
  56
  57 int watchdog_frequency(int frequency)
  58 {
  59         if (wdt_fd < 0)
  60                 return 0;
  61
  62         if (frequency) {
  63                 DEBUG(2, "Set watchdog frequency: %ds\n", frequency);
  64                 wdt_frequency = frequency;
  65         }
  66
  67         return wdt_frequency;
  68 }
  69
  70 char* watchdog_fd(void)
  71 {
  72         static char fd_buf[3];
  73
  74         if (wdt_fd < 0)
  75                 return NULL;
  76         snprintf(fd_buf, sizeof(fd_buf), "%d", wdt_fd);
  77
  78         return fd_buf;
  79 }
  80
  81 void watchdog_init(void)
  82 {
  83         char *env = getenv("WDTFD");
  84
  85         wdt_timeout.cb = watchdog_timeout_cb;
  86         if (env) {
  87                 LOG("- watchdog -\n");
  88                 DEBUG(1, "Watchdog handover: fd=%s\n", env);
  89                 wdt_fd = atoi(env);
  90                 fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
  91                 unsetenv("WDTFD");
  92         } else {
  93                 wdt_fd = open("/dev/watchdog", O_WRONLY);
  94                 if (getpid() != 1)
  95                         fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
  96         }
  97         if (wdt_fd < 0)
  98                 return;
  99         watchdog_timeout(30);
 100         watchdog_timeout_cb(&wdt_timeout);
 101
 102         DEBUG(2, "Opened watchdog with timeout %ds\n", watchdog_timeout(0));
 103 }