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.
12 //usage:#define watchdog_trivial_usage
13 //usage: "[-t N[ms]] [-T N[ms]] [-F] DEV"
14 //usage:#define watchdog_full_usage "\n\n"
15 //usage: "Periodically write to watchdog device DEV\n"
16 //usage: "\n -T N Reboot after N seconds if not reset (default 60)"
17 //usage: "\n -t N Reset every N seconds (default 30)"
18 //usage: "\n -F Run in foreground"
20 //usage: "\nUse 500ms to specify period in milliseconds"
23 #include "linux/types.h" /* for __u32 */
24 #include "linux/watchdog.h"
26 #define OPT_FOREGROUND (1 << 0)
27 #define OPT_STIMER (1 << 1)
28 #define OPT_HTIMER (1 << 2)
30 static void watchdog_shutdown(int sig UNUSED_PARAM
)
32 static const char V
= 'V';
34 remove_pidfile(CONFIG_PID_FILE_PATH
"/watchdog.pid");
35 write(3, &V
, 1); /* Magic, see watchdog-api.txt in kernel */
36 if (ENABLE_FEATURE_CLEAN_UP
)
41 int watchdog_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
42 int watchdog_main(int argc
, char **argv
)
44 static const struct suffix_mult suffixes
[] = {
51 unsigned stimer_duration
; /* how often to restart */
52 unsigned htimer_duration
= 60000; /* reboots after N ms if not restarted */
56 opt_complementary
= "=1"; /* must have exactly 1 argument */
57 opts
= getopt32(argv
, "Ft:T:", &st_arg
, &ht_arg
);
59 /* We need to daemonize *before* opening the watchdog as many drivers
60 * will only allow one process at a time to do so. Since daemonizing
61 * is not perfect (child may run before parent finishes exiting), we
62 * can't rely on parent exiting before us (let alone *cleanly* releasing
63 * the watchdog fd -- something else that may not even be allowed).
65 if (!(opts
& OPT_FOREGROUND
))
66 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT
, argv
);
68 if (opts
& OPT_HTIMER
)
69 htimer_duration
= xatou_sfx(ht_arg
, suffixes
);
70 stimer_duration
= htimer_duration
/ 2;
71 if (opts
& OPT_STIMER
)
72 stimer_duration
= xatou_sfx(st_arg
, suffixes
);
74 bb_signals(BB_FATAL_SIGS
, watchdog_shutdown
);
76 /* Use known fd # - avoid needing global 'int fd' */
77 xmove_fd(xopen(argv
[argc
- 1], O_WRONLY
), 3);
79 /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */
80 htimer_duration
= htimer_duration
/ 1000;
81 #ifndef WDIOC_SETTIMEOUT
82 # error WDIOC_SETTIMEOUT is not defined, cannot compile watchdog applet
84 # if defined WDIOC_SETOPTIONS && defined WDIOS_ENABLECARD
86 static const int enable
= WDIOS_ENABLECARD
;
87 ioctl_or_warn(3, WDIOC_SETOPTIONS
, (void*) &enable
);
90 ioctl_or_warn(3, WDIOC_SETTIMEOUT
, &htimer_duration
);
94 ioctl_or_warn(3, WDIOC_GETTIMEOUT
, &htimer_duration
);
95 printf("watchdog: SW timer is %dms, HW timer is %ds\n",
96 stimer_duration
, htimer_duration
* 1000);
99 write_pidfile(CONFIG_PID_FILE_PATH
"/watchdog.pid");
103 * Make sure we clear the counter before sleeping,
104 * as the counter value is undefined at this point -- PFM
106 write(3, "", 1); /* write zero byte */
107 usleep(stimer_duration
* 1000L);
109 return EXIT_SUCCESS
; /* - not reached, but gcc 4.2.1 is too dumb! */