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39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
40
41#include <linux/module.h>
42#include <linux/moduleparam.h>
43#include <linux/types.h>
44#include <linux/timer.h>
45#include <linux/miscdevice.h>
46#include <linux/watchdog.h>
47#include <linux/notifier.h>
48#include <linux/reboot.h>
49#include <linux/init.h>
50#include <linux/jiffies.h>
51#include <linux/kernel.h>
52
53#define TIMER_MARGIN 60
54static unsigned int soft_margin = TIMER_MARGIN;
55module_param(soft_margin, uint, 0);
56MODULE_PARM_DESC(soft_margin,
57 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
58 __MODULE_STRING(TIMER_MARGIN) ")");
59
60static bool nowayout = WATCHDOG_NOWAYOUT;
61module_param(nowayout, bool, 0);
62MODULE_PARM_DESC(nowayout,
63 "Watchdog cannot be stopped once started (default="
64 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
65
66static int soft_noboot = 0;
67module_param(soft_noboot, int, 0);
68MODULE_PARM_DESC(soft_noboot,
69 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
70
71static int soft_panic;
72module_param(soft_panic, int, 0);
73MODULE_PARM_DESC(soft_panic,
74 "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
75
76
77
78
79
80static void watchdog_fire(unsigned long);
81
82static struct timer_list watchdog_ticktock =
83 TIMER_INITIALIZER(watchdog_fire, 0, 0);
84
85
86
87
88
89static void watchdog_fire(unsigned long data)
90{
91 if (soft_noboot)
92 pr_crit("Triggered - Reboot ignored\n");
93 else if (soft_panic) {
94 pr_crit("Initiating panic\n");
95 panic("Software Watchdog Timer expired");
96 } else {
97 pr_crit("Initiating system reboot\n");
98 emergency_restart();
99 pr_crit("Reboot didn't ?????\n");
100 }
101}
102
103
104
105
106
107static int softdog_ping(struct watchdog_device *w)
108{
109 mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
110 return 0;
111}
112
113static int softdog_stop(struct watchdog_device *w)
114{
115 del_timer(&watchdog_ticktock);
116 return 0;
117}
118
119static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
120{
121 w->timeout = t;
122 return 0;
123}
124
125
126
127
128
129static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
130 void *unused)
131{
132 if (code == SYS_DOWN || code == SYS_HALT)
133
134 softdog_stop(NULL);
135 return NOTIFY_DONE;
136}
137
138
139
140
141
142static struct notifier_block softdog_notifier = {
143 .notifier_call = softdog_notify_sys,
144};
145
146static struct watchdog_info softdog_info = {
147 .identity = "Software Watchdog",
148 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
149};
150
151static struct watchdog_ops softdog_ops = {
152 .owner = THIS_MODULE,
153 .start = softdog_ping,
154 .stop = softdog_stop,
155 .set_timeout = softdog_set_timeout,
156};
157
158static struct watchdog_device softdog_dev = {
159 .info = &softdog_info,
160 .ops = &softdog_ops,
161 .min_timeout = 1,
162 .max_timeout = 0xFFFF
163};
164
165static int __init watchdog_init(void)
166{
167 int ret;
168
169
170
171 if (soft_margin < 1 || soft_margin > 65535) {
172 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
173 TIMER_MARGIN);
174 return -EINVAL;
175 }
176 softdog_dev.timeout = soft_margin;
177
178 watchdog_set_nowayout(&softdog_dev, nowayout);
179
180 ret = register_reboot_notifier(&softdog_notifier);
181 if (ret) {
182 pr_err("cannot register reboot notifier (err=%d)\n", ret);
183 return ret;
184 }
185
186 ret = watchdog_register_device(&softdog_dev);
187 if (ret) {
188 unregister_reboot_notifier(&softdog_notifier);
189 return ret;
190 }
191
192 pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
193 soft_noboot, soft_margin, soft_panic, nowayout);
194
195 return 0;
196}
197
198static void __exit watchdog_exit(void)
199{
200 watchdog_unregister_device(&softdog_dev);
201 unregister_reboot_notifier(&softdog_notifier);
202}
203
204module_init(watchdog_init);
205module_exit(watchdog_exit);
206
207MODULE_AUTHOR("Alan Cox");
208MODULE_DESCRIPTION("Software Watchdog Device Driver");
209MODULE_LICENSE("GPL");
210MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
211