1 /* vi: set sw=4 ts=4: */
3 * Mini watchdog implementation for busybox
5 * Copyright (C) 2003 Paul Mundt <lethal@linux-sh.org>
6 * Copyright (C) 2006 Bernhard Reutner-Fischer <busybox@busybox.net>
7 * Copyright (C) 2008 Darius Augulis <augulis.darius@gmail.com>
9 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 //config:config WATCHDOG
12 //config: bool "watchdog"
14 //config: select PLATFORM_LINUX
16 //config: The watchdog utility is used with hardware or software watchdog
17 //config: device drivers. It opens the specified watchdog device special file
18 //config: and periodically writes a magic character to the device. If the
19 //config: watchdog applet ever fails to write the magic character within a
20 //config: certain amount of time, the watchdog device assumes the system has
21 //config: hung, and will cause the hardware to reboot.
23 //applet:IF_WATCHDOG(APPLET(watchdog, BB_DIR_SBIN, BB_SUID_DROP))
25 //kbuild:lib-$(CONFIG_WATCHDOG) += watchdog.o
27 //usage:#define watchdog_trivial_usage
28 //usage: "[-t N[ms]] [-T N[ms]] [-F] DEV"
29 //usage:#define watchdog_full_usage "\n\n"
30 //usage: "Periodically write to watchdog device DEV\n"
31 //usage: "\n -T N Reboot after N seconds if not reset (default 60)"
32 //usage: "\n -t N Reset every N seconds (default 30)"
33 //usage: "\n -F Run in foreground"
35 //usage: "\nUse 500ms to specify period in milliseconds"
38 #include "linux/types.h" /* for __u32 */
39 #include "linux/watchdog.h"
41 #define OPT_FOREGROUND (1 << 0)
42 #define OPT_STIMER (1 << 1)
43 #define OPT_HTIMER (1 << 2)
45 static void watchdog_shutdown(int sig UNUSED_PARAM)
47 static const char V = 'V';
49 remove_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
50 write(3, &V, 1); /* Magic, see watchdog-api.txt in kernel */
51 if (ENABLE_FEATURE_CLEAN_UP)
56 int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
57 int watchdog_main(int argc, char **argv)
59 static const struct suffix_mult suffixes[] = {
66 unsigned stimer_duration; /* how often to restart */
67 unsigned htimer_duration = 60000; /* reboots after N ms if not restarted */
71 opt_complementary = "=1"; /* must have exactly 1 argument */
72 opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
74 /* We need to daemonize *before* opening the watchdog as many drivers
75 * will only allow one process at a time to do so. Since daemonizing
76 * is not perfect (child may run before parent finishes exiting), we
77 * can't rely on parent exiting before us (let alone *cleanly* releasing
78 * the watchdog fd -- something else that may not even be allowed).
80 if (!(opts & OPT_FOREGROUND))
81 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
83 if (opts & OPT_HTIMER)
84 htimer_duration = xatou_sfx(ht_arg, suffixes);
85 stimer_duration = htimer_duration / 2;
86 if (opts & OPT_STIMER)
87 stimer_duration = xatou_sfx(st_arg, suffixes);
89 bb_signals(BB_FATAL_SIGS, watchdog_shutdown);
91 /* Use known fd # - avoid needing global 'int fd' */
92 xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3);
94 /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
95 htimer_duration = htimer_duration / 1000;
96 #ifndef WDIOC_SETTIMEOUT
97 # error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
99 # if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD
101 static const int enable = WDIOS_ENABLECARD;
102 ioctl_or_warn(3, WDIOC_SETOPTIONS, (void*) &enable);
105 ioctl_or_warn(3, WDIOC_SETTIMEOUT, &htimer_duration);
109 ioctl_or_warn(3, WDIOC_GETTIMEOUT, &htimer_duration);
110 printf("watchdog: SW timer is %dms, HW timer is %ds\n",
111 stimer_duration, htimer_duration * 1000);
114 write_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
118 * Make sure we clear the counter before sleeping,
119 * as the counter value is undefined at this point -- PFM
121 write(3, "", 1); /* write zero byte */
122 usleep(stimer_duration * 1000L);
124 return EXIT_SUCCESS; /* - not reached, but gcc 4.2.1 is too dumb! */