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 void watchdog_set_stopped(bool val)
  44 {
  45         if (val)
  46                 uloop_timeout_cancel(&wdt_timeout);
  47         else
  48                 watchdog_timeout_cb(&wdt_timeout);
  49 }
  50
  51 bool watchdog_get_stopped(void)
  52 {
  53         return !wdt_timeout.pending;
  54 }
  55
  56 int watchdog_timeout(int timeout)
  57 {
  58         if (wdt_fd < 0)
  59                 return 0;
  60
  61         if (timeout) {
  62                 DEBUG(2, "Set watchdog timeout: %ds\n", timeout);
  63                 ioctl(wdt_fd, WDIOC_SETTIMEOUT, &timeout);
  64         }
  65         ioctl(wdt_fd, WDIOC_GETTIMEOUT, &timeout);
  66
  67         return timeout;
  68 }
  69
  70 int watchdog_frequency(int frequency)
  71 {
  72         if (wdt_fd < 0)
  73                 return 0;
  74
  75         if (frequency) {
  76                 DEBUG(2, "Set watchdog frequency: %ds\n", frequency);
  77                 wdt_frequency = frequency;
  78         }
  79
  80         return wdt_frequency;
  81 }
  82
  83 char* watchdog_fd(void)
  84 {
  85         static char fd_buf[3];
  86
  87         if (wdt_fd < 0)
  88                 return NULL;
  89         snprintf(fd_buf, sizeof(fd_buf), "%d", wdt_fd);
  90
  91         return fd_buf;
  92 }
  93
  94 void watchdog_init(void)
  95 {
  96         char *env = getenv("WDTFD");
  97
  98         wdt_timeout.cb = watchdog_timeout_cb;
  99         if (env) {
 100                 LOG("- watchdog -\n");
 101                 DEBUG(1, "Watchdog handover: fd=%s\n", env);
 102                 wdt_fd = atoi(env);
 103                 fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
 104                 unsetenv("WDTFD");
 105         } else {
 106                 wdt_fd = open("/dev/watchdog", O_WRONLY);
 107                 if (getpid() != 1)
 108                         fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);
 109         }
 110         if (wdt_fd < 0)
 111                 return;
 112         watchdog_timeout(30);
 113         watchdog_timeout_cb(&wdt_timeout);
 114
 115         DEBUG(2, "Opened watchdog with timeout %ds\n", watchdog_timeout(0));
 116 }