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 void watchdog_ping(void)
  36 {
  37         DEBUG(4, "Ping\n");
  38         if (wdt_fd >= 0 && write(wdt_fd, "X", 1) < 0)
  39                 ERROR("WDT failed to write: %s\n", strerror(errno));
  40 }
  41
  42 static void watchdog_timeout_cb(struct uloop_timeout *t)
  43 {
  44         watchdog_ping();
  45         uloop_timeout_set(t, wdt_frequency * 1000);
  46 }
  47
  48 void watchdog_set_stopped(bool val)
  49 {
  50         if (val)
  51                 uloop_timeout_cancel(&wdt_timeout);
  52         else
  53                 watchdog_timeout_cb(&wdt_timeout);
  54 }
  55
  56 bool watchdog_get_stopped(void)
  57 {
  58         return !wdt_timeout.pending;
  59 }
  60
  61 int watchdog_timeout(int timeout)
  62 {
  63         if (wdt_fd < 0)
  64                 return 0;
  65
  66         if (timeout) {
  67                 DEBUG(4, "Set watchdog timeout: %ds\n", timeout);
  68                 ioctl(wdt_fd, WDIOC_SETTIMEOUT, &timeout);
  69         }
  70         ioctl(wdt_fd, WDIOC_GETTIMEOUT, &timeout);
  71
  72         return timeout;
  73 }
  74
  75 int watchdog_frequency(int frequency)
  76 {
  77         if (wdt_fd < 0)
  78                 return 0;
  79
  80         if (frequency) {
  81                 DEBUG(4, "Set watchdog frequency: %ds\n", frequency);
  82                 wdt_frequency = frequency;
  83         }
  84
  85         return wdt_frequency;
  86 }
  87
  88 char* watchdog_fd(void)
  89 {
  90         static char fd_buf[3];
  91
  92         if (wdt_fd < 0)
  93                 return NULL;
  94         snprintf(fd_buf, sizeof(fd_buf), "%d", wdt_fd);
  95
  96         return fd_buf;
  97 }
  98
  99 void watchdog_init(int preinit)
 100 {
 101         char *env = getenv("WDTFD");
 102
 103         if (wdt_fd >= 0)
 104                 return;
 105
 106         wdt_timeout.cb = watchdog_timeout_cb;
 107         if (env) {
 108                 DEBUG(2, "Watchdog handover: fd=%s\n", env);
 109                 wdt_fd = atoi(env);
 110                 unsetenv("WDTFD");
 111         } else {
 112                 wdt_fd = open("/dev/watchdog", O_WRONLY);
 113         }
 114
 115         if (wdt_fd < 0)
 116                 return;
 117
 118         if (!preinit)
 119                 fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
 120
 121         LOG("- watchdog -\n");
 122         watchdog_timeout(30);
 123         watchdog_timeout_cb(&wdt_timeout);
 124
 125         DEBUG(4, "Opened watchdog with timeout %ds\n", watchdog_timeout(0));
 126 }
 127
 128
 129 void watchdog_no_cloexec(void)
 130 {
 131         if (wdt_fd < 0)
 132                 return;
 133
 134         fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) & ~FD_CLOEXEC);
 135 }