4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
9 * This source code is part of the generic code that can be used
10 * by all the watchdog timer drivers.
12 * Based on source code of the following authors:
13 * Matt Domsch <Matt_Domsch@dell.com>,
14 * Rob Radez <rob@osinvestor.com>,
15 * Rusty Lynch <rusty@linux.co.intel.com>
16 * Satyam Sharma <satyam@infradead.org>
17 * Randy Dunlap <randy.dunlap@oracle.com>
19 * This program is free software; you can redistribute it and/or
20 * modify it under the terms of the GNU General Public License
21 * as published by the Free Software Foundation; either version
22 * 2 of the License, or (at your option) any later version.
24 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
25 * admit liability nor provide warranty for any of this software.
26 * This material is provided "AS-IS" and at no charge.
29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31 #include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */
32 #include <linux/types.h> /* For standard types */
33 #include <linux/errno.h> /* For the -ENODEV/... values */
34 #include <linux/kernel.h> /* For printk/panic/... */
35 #include <linux/reboot.h> /* For restart handler */
36 #include <linux/watchdog.h> /* For watchdog specific items */
37 #include <linux/init.h> /* For __init/__exit/... */
38 #include <linux/idr.h> /* For ida_* macros */
39 #include <linux/err.h> /* For IS_ERR macros */
40 #include <linux/of.h> /* For of_get_timeout_sec */
42 #include "watchdog_core.h" /* For watchdog_dev_register/... */
44 static DEFINE_IDA(watchdog_ida
);
47 * Deferred Registration infrastructure.
49 * Sometimes watchdog drivers needs to be loaded as soon as possible,
50 * for example when it's impossible to disable it. To do so,
51 * raising the initcall level of the watchdog driver is a solution.
52 * But in such case, the miscdev is maybe not ready (subsys_initcall), and
53 * watchdog_core need miscdev to register the watchdog as a char device.
55 * The deferred registration infrastructure offer a way for the watchdog
56 * subsystem to register a watchdog properly, even before miscdev is ready.
59 static DEFINE_MUTEX(wtd_deferred_reg_mutex
);
60 static LIST_HEAD(wtd_deferred_reg_list
);
61 static bool wtd_deferred_reg_done
;
63 static int watchdog_deferred_registration_add(struct watchdog_device
*wdd
)
65 list_add_tail(&wdd
->deferred
,
66 &wtd_deferred_reg_list
);
70 static void watchdog_deferred_registration_del(struct watchdog_device
*wdd
)
72 struct list_head
*p
, *n
;
73 struct watchdog_device
*wdd_tmp
;
75 list_for_each_safe(p
, n
, &wtd_deferred_reg_list
) {
76 wdd_tmp
= list_entry(p
, struct watchdog_device
,
79 list_del(&wdd_tmp
->deferred
);
85 static void watchdog_check_min_max_timeout(struct watchdog_device
*wdd
)
88 * Check that we have valid min and max timeout values, if
89 * not reset them both to 0 (=not used or unknown)
91 if (!wdd
->max_hw_heartbeat_ms
&& wdd
->min_timeout
> wdd
->max_timeout
) {
92 pr_info("Invalid min and max timeout values, resetting to 0!\n");
99 * watchdog_init_timeout() - initialize the timeout field
100 * @wdd: watchdog device
101 * @timeout_parm: timeout module parameter
102 * @dev: Device that stores the timeout-sec property
104 * Initialize the timeout field of the watchdog_device struct with either the
105 * timeout module parameter (if it is valid value) or the timeout-sec property
106 * (only if it is a valid value and the timeout_parm is out of bounds).
107 * If none of them are valid then we keep the old value (which should normally
108 * be the default timeout value).
110 * A zero is returned on success and -EINVAL for failure.
112 int watchdog_init_timeout(struct watchdog_device
*wdd
,
113 unsigned int timeout_parm
, struct device
*dev
)
118 watchdog_check_min_max_timeout(wdd
);
120 /* try to get the timeout module parameter first */
121 if (!watchdog_timeout_invalid(wdd
, timeout_parm
) && timeout_parm
) {
122 wdd
->timeout
= timeout_parm
;
128 /* try to get the timeout_sec property */
129 if (dev
== NULL
|| dev
->of_node
== NULL
)
131 of_property_read_u32(dev
->of_node
, "timeout-sec", &t
);
132 if (!watchdog_timeout_invalid(wdd
, t
) && t
)
139 EXPORT_SYMBOL_GPL(watchdog_init_timeout
);
141 static int watchdog_restart_notifier(struct notifier_block
*nb
,
142 unsigned long action
, void *data
)
144 struct watchdog_device
*wdd
= container_of(nb
, struct watchdog_device
,
149 ret
= wdd
->ops
->restart(wdd
, action
, data
);
157 * watchdog_set_restart_priority - Change priority of restart handler
158 * @wdd: watchdog device
159 * @priority: priority of the restart handler, should follow these guidelines:
160 * 0: use watchdog's restart function as last resort, has limited restart
162 * 128: default restart handler, use if no other handler is expected to be
163 * available and/or if restart is sufficient to restart the entire system
164 * 255: preempt all other handlers
166 * If a wdd->ops->restart function is provided when watchdog_register_device is
167 * called, it will be registered as a restart handler with the priority given
170 void watchdog_set_restart_priority(struct watchdog_device
*wdd
, int priority
)
172 wdd
->restart_nb
.priority
= priority
;
174 EXPORT_SYMBOL_GPL(watchdog_set_restart_priority
);
176 static int __watchdog_register_device(struct watchdog_device
*wdd
)
180 if (wdd
== NULL
|| wdd
->info
== NULL
|| wdd
->ops
== NULL
)
183 /* Mandatory operations need to be supported */
184 if (!wdd
->ops
->start
|| (!wdd
->ops
->stop
&& !wdd
->max_hw_heartbeat_ms
))
187 watchdog_check_min_max_timeout(wdd
);
190 * Note: now that all watchdog_device data has been verified, we
191 * will not check this anymore in other functions. If data gets
192 * corrupted in a later stage then we expect a kernel panic!
195 /* Use alias for watchdog id if possible */
197 ret
= of_alias_get_id(wdd
->parent
->of_node
, "watchdog");
199 id
= ida_simple_get(&watchdog_ida
, ret
,
200 ret
+ 1, GFP_KERNEL
);
204 id
= ida_simple_get(&watchdog_ida
, 0, MAX_DOGS
, GFP_KERNEL
);
210 ret
= watchdog_dev_register(wdd
);
212 ida_simple_remove(&watchdog_ida
, id
);
213 if (!(id
== 0 && ret
== -EBUSY
))
216 /* Retry in case a legacy watchdog module exists */
217 id
= ida_simple_get(&watchdog_ida
, 1, MAX_DOGS
, GFP_KERNEL
);
222 ret
= watchdog_dev_register(wdd
);
224 ida_simple_remove(&watchdog_ida
, id
);
229 if (wdd
->ops
->restart
) {
230 wdd
->restart_nb
.notifier_call
= watchdog_restart_notifier
;
232 ret
= register_restart_handler(&wdd
->restart_nb
);
234 pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
242 * watchdog_register_device() - register a watchdog device
243 * @wdd: watchdog device
245 * Register a watchdog device with the kernel so that the
246 * watchdog timer can be accessed from userspace.
248 * A zero is returned on success and a negative errno code for
252 int watchdog_register_device(struct watchdog_device
*wdd
)
256 mutex_lock(&wtd_deferred_reg_mutex
);
257 if (wtd_deferred_reg_done
)
258 ret
= __watchdog_register_device(wdd
);
260 ret
= watchdog_deferred_registration_add(wdd
);
261 mutex_unlock(&wtd_deferred_reg_mutex
);
264 EXPORT_SYMBOL_GPL(watchdog_register_device
);
266 static void __watchdog_unregister_device(struct watchdog_device
*wdd
)
271 if (wdd
->ops
->restart
)
272 unregister_restart_handler(&wdd
->restart_nb
);
274 watchdog_dev_unregister(wdd
);
275 ida_simple_remove(&watchdog_ida
, wdd
->id
);
279 * watchdog_unregister_device() - unregister a watchdog device
280 * @wdd: watchdog device to unregister
282 * Unregister a watchdog device that was previously successfully
283 * registered with watchdog_register_device().
286 void watchdog_unregister_device(struct watchdog_device
*wdd
)
288 mutex_lock(&wtd_deferred_reg_mutex
);
289 if (wtd_deferred_reg_done
)
290 __watchdog_unregister_device(wdd
);
292 watchdog_deferred_registration_del(wdd
);
293 mutex_unlock(&wtd_deferred_reg_mutex
);
296 EXPORT_SYMBOL_GPL(watchdog_unregister_device
);
298 static void devm_watchdog_unregister_device(struct device
*dev
, void *res
)
300 watchdog_unregister_device(*(struct watchdog_device
**)res
);
304 * devm_watchdog_register_device() - resource managed watchdog_register_device()
305 * @dev: device that is registering this watchdog device
306 * @wdd: watchdog device
308 * Managed watchdog_register_device(). For watchdog device registered by this
309 * function, watchdog_unregister_device() is automatically called on driver
310 * detach. See watchdog_register_device() for more information.
312 int devm_watchdog_register_device(struct device
*dev
,
313 struct watchdog_device
*wdd
)
315 struct watchdog_device
**rcwdd
;
318 rcwdd
= devres_alloc(devm_watchdog_unregister_device
, sizeof(*rcwdd
),
323 ret
= watchdog_register_device(wdd
);
326 devres_add(dev
, rcwdd
);
333 EXPORT_SYMBOL_GPL(devm_watchdog_register_device
);
335 static int __init
watchdog_deferred_registration(void)
337 mutex_lock(&wtd_deferred_reg_mutex
);
338 wtd_deferred_reg_done
= true;
339 while (!list_empty(&wtd_deferred_reg_list
)) {
340 struct watchdog_device
*wdd
;
342 wdd
= list_first_entry(&wtd_deferred_reg_list
,
343 struct watchdog_device
, deferred
);
344 list_del(&wdd
->deferred
);
345 __watchdog_register_device(wdd
);
347 mutex_unlock(&wtd_deferred_reg_mutex
);
351 static int __init
watchdog_init(void)
355 err
= watchdog_dev_init();
359 watchdog_deferred_registration();
363 static void __exit
watchdog_exit(void)
366 ida_destroy(&watchdog_ida
);
369 subsys_initcall_sync(watchdog_init
);
370 module_exit(watchdog_exit
);
372 MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
373 MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
374 MODULE_DESCRIPTION("WatchDog Timer Driver Core");
375 MODULE_LICENSE("GPL");