4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
10 * This source code is part of the generic code that can be used
11 * by all the watchdog timer drivers.
13 * This part of the generic code takes care of the following
14 * misc device: /dev/watchdog.
16 * Based on source code of the following authors:
17 * Matt Domsch <Matt_Domsch@dell.com>,
18 * Rob Radez <rob@osinvestor.com>,
19 * Rusty Lynch <rusty@linux.co.intel.com>
20 * Satyam Sharma <satyam@infradead.org>
21 * Randy Dunlap <randy.dunlap@oracle.com>
23 * This program is free software; you can redistribute it and/or
24 * modify it under the terms of the GNU General Public License
25 * as published by the Free Software Foundation; either version
26 * 2 of the License, or (at your option) any later version.
28 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
29 * admit liability nor provide warranty for any of this software.
30 * This material is provided "AS-IS" and at no charge.
33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35 #include <linux/cdev.h> /* For character device */
36 #include <linux/errno.h> /* For the -ENODEV/... values */
37 #include <linux/fs.h> /* For file operations */
38 #include <linux/init.h> /* For __init/__exit/... */
39 #include <linux/jiffies.h> /* For timeout functions */
40 #include <linux/kernel.h> /* For printk/panic/... */
41 #include <linux/miscdevice.h> /* For handling misc devices */
42 #include <linux/module.h> /* For module stuff/... */
43 #include <linux/mutex.h> /* For mutexes */
44 #include <linux/slab.h> /* For memory functions */
45 #include <linux/types.h> /* For standard types (like size_t) */
46 #include <linux/watchdog.h> /* For watchdog specific items */
47 #include <linux/workqueue.h> /* For workqueue */
48 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
50 #include "watchdog_core.h"
51 #include "watchdog_pretimeout.h"
54 * struct watchdog_core_data - watchdog core internal data
55 * @dev: The watchdog's internal device
56 * @cdev: The watchdog's Character device.
57 * @wdd: Pointer to watchdog device.
58 * @lock: Lock for watchdog core.
59 * @status: Watchdog core internal status bits.
61 struct watchdog_core_data
{
64 struct watchdog_device
*wdd
;
66 unsigned long last_keepalive
;
67 unsigned long last_hw_keepalive
;
68 struct delayed_work work
;
69 unsigned long status
; /* Internal status bits */
70 #define _WDOG_DEV_OPEN 0 /* Opened ? */
71 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
72 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
75 /* the dev_t structure to store the dynamically allocated watchdog devices */
76 static dev_t watchdog_devt
;
77 /* Reference to watchdog device behind /dev/watchdog */
78 static struct watchdog_core_data
*old_wd_data
;
80 static struct workqueue_struct
*watchdog_wq
;
82 static bool handle_boot_enabled
=
83 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED
);
85 static inline bool watchdog_need_worker(struct watchdog_device
*wdd
)
87 /* All variables in milli-seconds */
88 unsigned int hm
= wdd
->max_hw_heartbeat_ms
;
89 unsigned int t
= wdd
->timeout
* 1000;
92 * A worker to generate heartbeat requests is needed if all of the
93 * following conditions are true.
94 * - Userspace activated the watchdog.
95 * - The driver provided a value for the maximum hardware timeout, and
96 * thus is aware that the framework supports generating heartbeat
98 * - Userspace requests a longer timeout than the hardware can handle.
100 * Alternatively, if userspace has not opened the watchdog
101 * device, we take care of feeding the watchdog if it is
104 return (hm
&& watchdog_active(wdd
) && t
> hm
) ||
105 (t
&& !watchdog_active(wdd
) && watchdog_hw_running(wdd
));
108 static long watchdog_next_keepalive(struct watchdog_device
*wdd
)
110 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
111 unsigned int timeout_ms
= wdd
->timeout
* 1000;
112 unsigned long keepalive_interval
;
113 unsigned long last_heartbeat
;
114 unsigned long virt_timeout
;
115 unsigned int hw_heartbeat_ms
;
117 virt_timeout
= wd_data
->last_keepalive
+ msecs_to_jiffies(timeout_ms
);
118 hw_heartbeat_ms
= min_not_zero(timeout_ms
, wdd
->max_hw_heartbeat_ms
);
119 keepalive_interval
= msecs_to_jiffies(hw_heartbeat_ms
/ 2);
121 if (!watchdog_active(wdd
))
122 return keepalive_interval
;
125 * To ensure that the watchdog times out wdd->timeout seconds
126 * after the most recent ping from userspace, the last
127 * worker ping has to come in hw_heartbeat_ms before this timeout.
129 last_heartbeat
= virt_timeout
- msecs_to_jiffies(hw_heartbeat_ms
);
130 return min_t(long, last_heartbeat
- jiffies
, keepalive_interval
);
133 static inline void watchdog_update_worker(struct watchdog_device
*wdd
)
135 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
137 if (watchdog_need_worker(wdd
)) {
138 long t
= watchdog_next_keepalive(wdd
);
141 mod_delayed_work(watchdog_wq
, &wd_data
->work
, t
);
143 cancel_delayed_work(&wd_data
->work
);
147 static int __watchdog_ping(struct watchdog_device
*wdd
)
149 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
150 unsigned long earliest_keepalive
= wd_data
->last_hw_keepalive
+
151 msecs_to_jiffies(wdd
->min_hw_heartbeat_ms
);
154 if (time_is_after_jiffies(earliest_keepalive
)) {
155 mod_delayed_work(watchdog_wq
, &wd_data
->work
,
156 earliest_keepalive
- jiffies
);
160 wd_data
->last_hw_keepalive
= jiffies
;
163 err
= wdd
->ops
->ping(wdd
); /* ping the watchdog */
165 err
= wdd
->ops
->start(wdd
); /* restart watchdog */
167 watchdog_update_worker(wdd
);
173 * watchdog_ping: ping the watchdog.
174 * @wdd: the watchdog device to ping
176 * The caller must hold wd_data->lock.
178 * If the watchdog has no own ping operation then it needs to be
179 * restarted via the start operation. This wrapper function does
181 * We only ping when the watchdog device is running.
184 static int watchdog_ping(struct watchdog_device
*wdd
)
186 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
188 if (!watchdog_active(wdd
) && !watchdog_hw_running(wdd
))
191 set_bit(_WDOG_KEEPALIVE
, &wd_data
->status
);
193 wd_data
->last_keepalive
= jiffies
;
194 return __watchdog_ping(wdd
);
197 static bool watchdog_worker_should_ping(struct watchdog_core_data
*wd_data
)
199 struct watchdog_device
*wdd
= wd_data
->wdd
;
201 return wdd
&& (watchdog_active(wdd
) || watchdog_hw_running(wdd
));
204 static void watchdog_ping_work(struct work_struct
*work
)
206 struct watchdog_core_data
*wd_data
;
208 wd_data
= container_of(to_delayed_work(work
), struct watchdog_core_data
,
211 mutex_lock(&wd_data
->lock
);
212 if (watchdog_worker_should_ping(wd_data
))
213 __watchdog_ping(wd_data
->wdd
);
214 mutex_unlock(&wd_data
->lock
);
218 * watchdog_start: wrapper to start the watchdog.
219 * @wdd: the watchdog device to start
221 * The caller must hold wd_data->lock.
223 * Start the watchdog if it is not active and mark it active.
224 * This function returns zero on success or a negative errno code for
228 static int watchdog_start(struct watchdog_device
*wdd
)
230 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
231 unsigned long started_at
;
234 if (watchdog_active(wdd
))
237 set_bit(_WDOG_KEEPALIVE
, &wd_data
->status
);
239 started_at
= jiffies
;
240 if (watchdog_hw_running(wdd
) && wdd
->ops
->ping
)
241 err
= wdd
->ops
->ping(wdd
);
243 err
= wdd
->ops
->start(wdd
);
245 set_bit(WDOG_ACTIVE
, &wdd
->status
);
246 wd_data
->last_keepalive
= started_at
;
247 watchdog_update_worker(wdd
);
254 * watchdog_stop: wrapper to stop the watchdog.
255 * @wdd: the watchdog device to stop
257 * The caller must hold wd_data->lock.
259 * Stop the watchdog if it is still active and unmark it active.
260 * This function returns zero on success or a negative errno code for
262 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
265 static int watchdog_stop(struct watchdog_device
*wdd
)
269 if (!watchdog_active(wdd
))
272 if (test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
)) {
273 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
278 if (wdd
->ops
->stop
) {
279 clear_bit(WDOG_HW_RUNNING
, &wdd
->status
);
280 err
= wdd
->ops
->stop(wdd
);
282 set_bit(WDOG_HW_RUNNING
, &wdd
->status
);
286 clear_bit(WDOG_ACTIVE
, &wdd
->status
);
287 watchdog_update_worker(wdd
);
294 * watchdog_get_status: wrapper to get the watchdog status
295 * @wdd: the watchdog device to get the status from
297 * The caller must hold wd_data->lock.
299 * Get the watchdog's status flags.
302 static unsigned int watchdog_get_status(struct watchdog_device
*wdd
)
304 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
307 if (wdd
->ops
->status
)
308 status
= wdd
->ops
->status(wdd
);
310 status
= wdd
->bootstatus
& (WDIOF_CARDRESET
|
318 if (test_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
))
319 status
|= WDIOF_MAGICCLOSE
;
321 if (test_and_clear_bit(_WDOG_KEEPALIVE
, &wd_data
->status
))
322 status
|= WDIOF_KEEPALIVEPING
;
328 * watchdog_set_timeout: set the watchdog timer timeout
329 * @wdd: the watchdog device to set the timeout for
330 * @timeout: timeout to set in seconds
332 * The caller must hold wd_data->lock.
335 static int watchdog_set_timeout(struct watchdog_device
*wdd
,
336 unsigned int timeout
)
340 if (!(wdd
->info
->options
& WDIOF_SETTIMEOUT
))
343 if (watchdog_timeout_invalid(wdd
, timeout
))
346 if (wdd
->ops
->set_timeout
) {
347 err
= wdd
->ops
->set_timeout(wdd
, timeout
);
349 wdd
->timeout
= timeout
;
350 /* Disable pretimeout if it doesn't fit the new timeout */
351 if (wdd
->pretimeout
>= wdd
->timeout
)
355 watchdog_update_worker(wdd
);
361 * watchdog_set_pretimeout: set the watchdog timer pretimeout
362 * @wdd: the watchdog device to set the timeout for
363 * @timeout: pretimeout to set in seconds
366 static int watchdog_set_pretimeout(struct watchdog_device
*wdd
,
367 unsigned int timeout
)
371 if (!(wdd
->info
->options
& WDIOF_PRETIMEOUT
))
374 if (watchdog_pretimeout_invalid(wdd
, timeout
))
377 if (wdd
->ops
->set_pretimeout
)
378 err
= wdd
->ops
->set_pretimeout(wdd
, timeout
);
380 wdd
->pretimeout
= timeout
;
386 * watchdog_get_timeleft: wrapper to get the time left before a reboot
387 * @wdd: the watchdog device to get the remaining time from
388 * @timeleft: the time that's left
390 * The caller must hold wd_data->lock.
392 * Get the time before a watchdog will reboot (if not pinged).
395 static int watchdog_get_timeleft(struct watchdog_device
*wdd
,
396 unsigned int *timeleft
)
400 if (!wdd
->ops
->get_timeleft
)
403 *timeleft
= wdd
->ops
->get_timeleft(wdd
);
408 #ifdef CONFIG_WATCHDOG_SYSFS
409 static ssize_t
nowayout_show(struct device
*dev
, struct device_attribute
*attr
,
412 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
414 return sprintf(buf
, "%d\n", !!test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
));
416 static DEVICE_ATTR_RO(nowayout
);
418 static ssize_t
status_show(struct device
*dev
, struct device_attribute
*attr
,
421 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
422 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
425 mutex_lock(&wd_data
->lock
);
426 status
= watchdog_get_status(wdd
);
427 mutex_unlock(&wd_data
->lock
);
429 return sprintf(buf
, "0x%x\n", status
);
431 static DEVICE_ATTR_RO(status
);
433 static ssize_t
bootstatus_show(struct device
*dev
,
434 struct device_attribute
*attr
, char *buf
)
436 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
438 return sprintf(buf
, "%u\n", wdd
->bootstatus
);
440 static DEVICE_ATTR_RO(bootstatus
);
442 static ssize_t
timeleft_show(struct device
*dev
, struct device_attribute
*attr
,
445 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
446 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
450 mutex_lock(&wd_data
->lock
);
451 status
= watchdog_get_timeleft(wdd
, &val
);
452 mutex_unlock(&wd_data
->lock
);
454 status
= sprintf(buf
, "%u\n", val
);
458 static DEVICE_ATTR_RO(timeleft
);
460 static ssize_t
timeout_show(struct device
*dev
, struct device_attribute
*attr
,
463 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
465 return sprintf(buf
, "%u\n", wdd
->timeout
);
467 static DEVICE_ATTR_RO(timeout
);
469 static ssize_t
pretimeout_show(struct device
*dev
,
470 struct device_attribute
*attr
, char *buf
)
472 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
474 return sprintf(buf
, "%u\n", wdd
->pretimeout
);
476 static DEVICE_ATTR_RO(pretimeout
);
478 static ssize_t
identity_show(struct device
*dev
, struct device_attribute
*attr
,
481 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
483 return sprintf(buf
, "%s\n", wdd
->info
->identity
);
485 static DEVICE_ATTR_RO(identity
);
487 static ssize_t
state_show(struct device
*dev
, struct device_attribute
*attr
,
490 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
492 if (watchdog_active(wdd
))
493 return sprintf(buf
, "active\n");
495 return sprintf(buf
, "inactive\n");
497 static DEVICE_ATTR_RO(state
);
499 static ssize_t
pretimeout_available_governors_show(struct device
*dev
,
500 struct device_attribute
*attr
, char *buf
)
502 return watchdog_pretimeout_available_governors_get(buf
);
504 static DEVICE_ATTR_RO(pretimeout_available_governors
);
506 static ssize_t
pretimeout_governor_show(struct device
*dev
,
507 struct device_attribute
*attr
,
510 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
512 return watchdog_pretimeout_governor_get(wdd
, buf
);
515 static ssize_t
pretimeout_governor_store(struct device
*dev
,
516 struct device_attribute
*attr
,
517 const char *buf
, size_t count
)
519 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
520 int ret
= watchdog_pretimeout_governor_set(wdd
, buf
);
527 static DEVICE_ATTR_RW(pretimeout_governor
);
529 static umode_t
wdt_is_visible(struct kobject
*kobj
, struct attribute
*attr
,
532 struct device
*dev
= container_of(kobj
, struct device
, kobj
);
533 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
534 umode_t mode
= attr
->mode
;
536 if (attr
== &dev_attr_timeleft
.attr
&& !wdd
->ops
->get_timeleft
)
538 else if (attr
== &dev_attr_pretimeout
.attr
&&
539 !(wdd
->info
->options
& WDIOF_PRETIMEOUT
))
541 else if ((attr
== &dev_attr_pretimeout_governor
.attr
||
542 attr
== &dev_attr_pretimeout_available_governors
.attr
) &&
543 (!(wdd
->info
->options
& WDIOF_PRETIMEOUT
) ||
544 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV
)))
549 static struct attribute
*wdt_attrs
[] = {
550 &dev_attr_state
.attr
,
551 &dev_attr_identity
.attr
,
552 &dev_attr_timeout
.attr
,
553 &dev_attr_pretimeout
.attr
,
554 &dev_attr_timeleft
.attr
,
555 &dev_attr_bootstatus
.attr
,
556 &dev_attr_status
.attr
,
557 &dev_attr_nowayout
.attr
,
558 &dev_attr_pretimeout_governor
.attr
,
559 &dev_attr_pretimeout_available_governors
.attr
,
563 static const struct attribute_group wdt_group
= {
565 .is_visible
= wdt_is_visible
,
567 __ATTRIBUTE_GROUPS(wdt
);
569 #define wdt_groups NULL
573 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
574 * @wdd: the watchdog device to do the ioctl on
575 * @cmd: watchdog command
576 * @arg: argument pointer
578 * The caller must hold wd_data->lock.
581 static int watchdog_ioctl_op(struct watchdog_device
*wdd
, unsigned int cmd
,
584 if (!wdd
->ops
->ioctl
)
587 return wdd
->ops
->ioctl(wdd
, cmd
, arg
);
591 * watchdog_write: writes to the watchdog.
592 * @file: file from VFS
593 * @data: user address of data
594 * @len: length of data
595 * @ppos: pointer to the file offset
597 * A write to a watchdog device is defined as a keepalive ping.
598 * Writing the magic 'V' sequence allows the next close to turn
599 * off the watchdog (if 'nowayout' is not set).
602 static ssize_t
watchdog_write(struct file
*file
, const char __user
*data
,
603 size_t len
, loff_t
*ppos
)
605 struct watchdog_core_data
*wd_data
= file
->private_data
;
606 struct watchdog_device
*wdd
;
615 * Note: just in case someone wrote the magic character
618 clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
620 /* scan to see whether or not we got the magic character */
621 for (i
= 0; i
!= len
; i
++) {
622 if (get_user(c
, data
+ i
))
625 set_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
628 /* someone wrote to us, so we send the watchdog a keepalive ping */
631 mutex_lock(&wd_data
->lock
);
634 err
= watchdog_ping(wdd
);
635 mutex_unlock(&wd_data
->lock
);
644 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
645 * @file: file handle to the device
646 * @cmd: watchdog command
647 * @arg: argument pointer
649 * The watchdog API defines a common set of functions for all watchdogs
650 * according to their available features.
653 static long watchdog_ioctl(struct file
*file
, unsigned int cmd
,
656 struct watchdog_core_data
*wd_data
= file
->private_data
;
657 void __user
*argp
= (void __user
*)arg
;
658 struct watchdog_device
*wdd
;
659 int __user
*p
= argp
;
663 mutex_lock(&wd_data
->lock
);
671 err
= watchdog_ioctl_op(wdd
, cmd
, arg
);
672 if (err
!= -ENOIOCTLCMD
)
676 case WDIOC_GETSUPPORT
:
677 err
= copy_to_user(argp
, wdd
->info
,
678 sizeof(struct watchdog_info
)) ? -EFAULT
: 0;
680 case WDIOC_GETSTATUS
:
681 val
= watchdog_get_status(wdd
);
682 err
= put_user(val
, p
);
684 case WDIOC_GETBOOTSTATUS
:
685 err
= put_user(wdd
->bootstatus
, p
);
687 case WDIOC_SETOPTIONS
:
688 if (get_user(val
, p
)) {
692 if (val
& WDIOS_DISABLECARD
) {
693 err
= watchdog_stop(wdd
);
697 if (val
& WDIOS_ENABLECARD
)
698 err
= watchdog_start(wdd
);
700 case WDIOC_KEEPALIVE
:
701 if (!(wdd
->info
->options
& WDIOF_KEEPALIVEPING
)) {
705 err
= watchdog_ping(wdd
);
707 case WDIOC_SETTIMEOUT
:
708 if (get_user(val
, p
)) {
712 err
= watchdog_set_timeout(wdd
, val
);
715 /* If the watchdog is active then we send a keepalive ping
716 * to make sure that the watchdog keep's running (and if
717 * possible that it takes the new timeout) */
718 err
= watchdog_ping(wdd
);
722 case WDIOC_GETTIMEOUT
:
723 /* timeout == 0 means that we don't know the timeout */
724 if (wdd
->timeout
== 0) {
728 err
= put_user(wdd
->timeout
, p
);
730 case WDIOC_GETTIMELEFT
:
731 err
= watchdog_get_timeleft(wdd
, &val
);
734 err
= put_user(val
, p
);
736 case WDIOC_SETPRETIMEOUT
:
737 if (get_user(val
, p
)) {
741 err
= watchdog_set_pretimeout(wdd
, val
);
743 case WDIOC_GETPRETIMEOUT
:
744 err
= put_user(wdd
->pretimeout
, p
);
752 mutex_unlock(&wd_data
->lock
);
757 * watchdog_open: open the /dev/watchdog* devices.
758 * @inode: inode of device
759 * @file: file handle to device
761 * When the /dev/watchdog* device gets opened, we start the watchdog.
762 * Watch out: the /dev/watchdog device is single open, so we make sure
763 * it can only be opened once.
766 static int watchdog_open(struct inode
*inode
, struct file
*file
)
768 struct watchdog_core_data
*wd_data
;
769 struct watchdog_device
*wdd
;
773 /* Get the corresponding watchdog device */
774 if (imajor(inode
) == MISC_MAJOR
)
775 wd_data
= old_wd_data
;
777 wd_data
= container_of(inode
->i_cdev
, struct watchdog_core_data
,
780 /* the watchdog is single open! */
781 if (test_and_set_bit(_WDOG_DEV_OPEN
, &wd_data
->status
))
787 * If the /dev/watchdog device is open, we don't want the module
790 hw_running
= watchdog_hw_running(wdd
);
791 if (!hw_running
&& !try_module_get(wdd
->ops
->owner
)) {
796 err
= watchdog_start(wdd
);
800 file
->private_data
= wd_data
;
803 get_device(&wd_data
->dev
);
805 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
806 return nonseekable_open(inode
, file
);
809 module_put(wd_data
->wdd
->ops
->owner
);
811 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
815 static void watchdog_core_data_release(struct device
*dev
)
817 struct watchdog_core_data
*wd_data
;
819 wd_data
= container_of(dev
, struct watchdog_core_data
, dev
);
825 * watchdog_release: release the watchdog device.
826 * @inode: inode of device
827 * @file: file handle to device
829 * This is the code for when /dev/watchdog gets closed. We will only
830 * stop the watchdog when we have received the magic char (and nowayout
831 * was not set), else the watchdog will keep running.
834 static int watchdog_release(struct inode
*inode
, struct file
*file
)
836 struct watchdog_core_data
*wd_data
= file
->private_data
;
837 struct watchdog_device
*wdd
;
841 mutex_lock(&wd_data
->lock
);
848 * We only stop the watchdog if we received the magic character
849 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
850 * watchdog_stop will fail.
852 if (!test_bit(WDOG_ACTIVE
, &wdd
->status
))
854 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
) ||
855 !(wdd
->info
->options
& WDIOF_MAGICCLOSE
))
856 err
= watchdog_stop(wdd
);
858 /* If the watchdog was not stopped, send a keepalive ping */
860 pr_crit("watchdog%d: watchdog did not stop!\n", wdd
->id
);
864 watchdog_update_worker(wdd
);
866 /* make sure that /dev/watchdog can be re-opened */
867 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
870 running
= wdd
&& watchdog_hw_running(wdd
);
871 mutex_unlock(&wd_data
->lock
);
873 * Allow the owner module to be unloaded again unless the watchdog
874 * is still running. If the watchdog is still running, it can not
875 * be stopped, and its driver must not be unloaded.
878 module_put(wd_data
->cdev
.owner
);
879 put_device(&wd_data
->dev
);
884 static const struct file_operations watchdog_fops
= {
885 .owner
= THIS_MODULE
,
886 .write
= watchdog_write
,
887 .unlocked_ioctl
= watchdog_ioctl
,
888 .open
= watchdog_open
,
889 .release
= watchdog_release
,
892 static struct miscdevice watchdog_miscdev
= {
893 .minor
= WATCHDOG_MINOR
,
895 .fops
= &watchdog_fops
,
898 static struct class watchdog_class
= {
900 .owner
= THIS_MODULE
,
901 .dev_groups
= wdt_groups
,
905 * watchdog_cdev_register: register watchdog character device
906 * @wdd: watchdog device
908 * Register a watchdog character device including handling the legacy
909 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
910 * thus we set it up like that.
913 static int watchdog_cdev_register(struct watchdog_device
*wdd
)
915 struct watchdog_core_data
*wd_data
;
918 wd_data
= kzalloc(sizeof(struct watchdog_core_data
), GFP_KERNEL
);
921 mutex_init(&wd_data
->lock
);
924 wdd
->wd_data
= wd_data
;
929 INIT_DELAYED_WORK(&wd_data
->work
, watchdog_ping_work
);
932 old_wd_data
= wd_data
;
933 watchdog_miscdev
.parent
= wdd
->parent
;
934 err
= misc_register(&watchdog_miscdev
);
936 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
937 wdd
->info
->identity
, WATCHDOG_MINOR
, err
);
939 pr_err("%s: a legacy watchdog module is probably present.\n",
940 wdd
->info
->identity
);
947 device_initialize(&wd_data
->dev
);
948 wd_data
->dev
.devt
= MKDEV(MAJOR(watchdog_devt
), wdd
->id
);
949 wd_data
->dev
.class = &watchdog_class
;
950 wd_data
->dev
.parent
= wdd
->parent
;
951 wd_data
->dev
.groups
= wdd
->groups
;
952 wd_data
->dev
.release
= watchdog_core_data_release
;
953 dev_set_drvdata(&wd_data
->dev
, wdd
);
954 dev_set_name(&wd_data
->dev
, "watchdog%d", wdd
->id
);
956 /* Fill in the data structures */
957 cdev_init(&wd_data
->cdev
, &watchdog_fops
);
960 err
= cdev_device_add(&wd_data
->cdev
, &wd_data
->dev
);
962 pr_err("watchdog%d unable to add device %d:%d\n",
963 wdd
->id
, MAJOR(watchdog_devt
), wdd
->id
);
965 misc_deregister(&watchdog_miscdev
);
967 put_device(&wd_data
->dev
);
972 wd_data
->cdev
.owner
= wdd
->ops
->owner
;
974 /* Record time of most recent heartbeat as 'just before now'. */
975 wd_data
->last_hw_keepalive
= jiffies
- 1;
978 * If the watchdog is running, prevent its driver from being unloaded,
979 * and schedule an immediate ping.
981 if (watchdog_hw_running(wdd
)) {
982 __module_get(wdd
->ops
->owner
);
983 get_device(&wd_data
->dev
);
984 if (handle_boot_enabled
)
985 queue_delayed_work(watchdog_wq
, &wd_data
->work
, 0);
987 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
995 * watchdog_cdev_unregister: unregister watchdog character device
996 * @watchdog: watchdog device
998 * Unregister watchdog character device and if needed the legacy
999 * /dev/watchdog device.
1002 static void watchdog_cdev_unregister(struct watchdog_device
*wdd
)
1004 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
1006 cdev_device_del(&wd_data
->cdev
, &wd_data
->dev
);
1008 misc_deregister(&watchdog_miscdev
);
1012 if (watchdog_active(wdd
) &&
1013 test_bit(WDOG_STOP_ON_UNREGISTER
, &wdd
->status
)) {
1017 mutex_lock(&wd_data
->lock
);
1018 wd_data
->wdd
= NULL
;
1019 wdd
->wd_data
= NULL
;
1020 mutex_unlock(&wd_data
->lock
);
1022 cancel_delayed_work_sync(&wd_data
->work
);
1024 put_device(&wd_data
->dev
);
1028 * watchdog_dev_register: register a watchdog device
1029 * @wdd: watchdog device
1031 * Register a watchdog device including handling the legacy
1032 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1033 * thus we set it up like that.
1036 int watchdog_dev_register(struct watchdog_device
*wdd
)
1040 ret
= watchdog_cdev_register(wdd
);
1044 ret
= watchdog_register_pretimeout(wdd
);
1046 watchdog_cdev_unregister(wdd
);
1052 * watchdog_dev_unregister: unregister a watchdog device
1053 * @watchdog: watchdog device
1055 * Unregister watchdog device and if needed the legacy
1056 * /dev/watchdog device.
1059 void watchdog_dev_unregister(struct watchdog_device
*wdd
)
1061 watchdog_unregister_pretimeout(wdd
);
1062 watchdog_cdev_unregister(wdd
);
1066 * watchdog_dev_init: init dev part of watchdog core
1068 * Allocate a range of chardev nodes to use for watchdog devices
1071 int __init
watchdog_dev_init(void)
1075 watchdog_wq
= alloc_workqueue("watchdogd",
1076 WQ_HIGHPRI
| WQ_MEM_RECLAIM
, 0);
1078 pr_err("Failed to create watchdog workqueue\n");
1082 err
= class_register(&watchdog_class
);
1084 pr_err("couldn't register class\n");
1088 err
= alloc_chrdev_region(&watchdog_devt
, 0, MAX_DOGS
, "watchdog");
1090 pr_err("watchdog: unable to allocate char dev region\n");
1097 class_unregister(&watchdog_class
);
1099 destroy_workqueue(watchdog_wq
);
1104 * watchdog_dev_exit: exit dev part of watchdog core
1106 * Release the range of chardev nodes used for watchdog devices
1109 void __exit
watchdog_dev_exit(void)
1111 unregister_chrdev_region(watchdog_devt
, MAX_DOGS
);
1112 class_unregister(&watchdog_class
);
1113 destroy_workqueue(watchdog_wq
);
1116 module_param(handle_boot_enabled
, bool, 0444);
1117 MODULE_PARM_DESC(handle_boot_enabled
,
1118 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1119 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED
)) ")");