1 // SPDX-License-Identifier: GPL-2.0+
5 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
8 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
11 * This source code is part of the generic code that can be used
12 * by all the watchdog timer drivers.
14 * This part of the generic code takes care of the following
15 * misc device: /dev/watchdog.
17 * Based on source code of the following authors:
18 * Matt Domsch <Matt_Domsch@dell.com>,
19 * Rob Radez <rob@osinvestor.com>,
20 * Rusty Lynch <rusty@linux.co.intel.com>
21 * Satyam Sharma <satyam@infradead.org>
22 * Randy Dunlap <randy.dunlap@oracle.com>
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/cdev.h> /* For character device */
32 #include <linux/errno.h> /* For the -ENODEV/... values */
33 #include <linux/fs.h> /* For file operations */
34 #include <linux/init.h> /* For __init/__exit/... */
35 #include <linux/hrtimer.h> /* For hrtimers */
36 #include <linux/kernel.h> /* For printk/panic/... */
37 #include <linux/kref.h> /* For data references */
38 #include <linux/kthread.h> /* For kthread_work */
39 #include <linux/miscdevice.h> /* For handling misc devices */
40 #include <linux/module.h> /* For module stuff/... */
41 #include <linux/mutex.h> /* For mutexes */
42 #include <linux/reboot.h> /* For reboot notifier */
43 #include <linux/slab.h> /* For memory functions */
44 #include <linux/types.h> /* For standard types (like size_t) */
45 #include <linux/watchdog.h> /* For watchdog specific items */
46 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
48 #include <uapi/linux/sched/types.h> /* For struct sched_param */
50 #include "watchdog_core.h"
51 #include "watchdog_pretimeout.h"
54 * struct watchdog_core_data - watchdog core internal data
55 * @kref: Reference count.
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 ktime_t last_keepalive
;
67 ktime_t last_hw_keepalive
;
68 ktime_t open_deadline
;
70 struct kthread_work work
;
71 unsigned long status
; /* Internal status bits */
72 #define _WDOG_DEV_OPEN 0 /* Opened ? */
73 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
74 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
77 /* the dev_t structure to store the dynamically allocated watchdog devices */
78 static dev_t watchdog_devt
;
79 /* Reference to watchdog device behind /dev/watchdog */
80 static struct watchdog_core_data
*old_wd_data
;
82 static struct kthread_worker
*watchdog_kworker
;
84 static bool handle_boot_enabled
=
85 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED
);
87 static unsigned open_timeout
= CONFIG_WATCHDOG_OPEN_TIMEOUT
;
89 static bool watchdog_past_open_deadline(struct watchdog_core_data
*data
)
91 return ktime_after(ktime_get(), data
->open_deadline
);
94 static void watchdog_set_open_deadline(struct watchdog_core_data
*data
)
96 data
->open_deadline
= open_timeout
?
97 ktime_get() + ktime_set(open_timeout
, 0) : KTIME_MAX
;
100 static inline bool watchdog_need_worker(struct watchdog_device
*wdd
)
102 /* All variables in milli-seconds */
103 unsigned int hm
= wdd
->max_hw_heartbeat_ms
;
104 unsigned int t
= wdd
->timeout
* 1000;
107 * A worker to generate heartbeat requests is needed if all of the
108 * following conditions are true.
109 * - Userspace activated the watchdog.
110 * - The driver provided a value for the maximum hardware timeout, and
111 * thus is aware that the framework supports generating heartbeat
113 * - Userspace requests a longer timeout than the hardware can handle.
115 * Alternatively, if userspace has not opened the watchdog
116 * device, we take care of feeding the watchdog if it is
119 return (hm
&& watchdog_active(wdd
) && t
> hm
) ||
120 (t
&& !watchdog_active(wdd
) && watchdog_hw_running(wdd
));
123 static ktime_t
watchdog_next_keepalive(struct watchdog_device
*wdd
)
125 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
126 unsigned int timeout_ms
= wdd
->timeout
* 1000;
127 ktime_t keepalive_interval
;
128 ktime_t last_heartbeat
, latest_heartbeat
;
129 ktime_t virt_timeout
;
130 unsigned int hw_heartbeat_ms
;
132 if (watchdog_active(wdd
))
133 virt_timeout
= ktime_add(wd_data
->last_keepalive
,
134 ms_to_ktime(timeout_ms
));
136 virt_timeout
= wd_data
->open_deadline
;
138 hw_heartbeat_ms
= min_not_zero(timeout_ms
, wdd
->max_hw_heartbeat_ms
);
139 keepalive_interval
= ms_to_ktime(hw_heartbeat_ms
/ 2);
142 * To ensure that the watchdog times out wdd->timeout seconds
143 * after the most recent ping from userspace, the last
144 * worker ping has to come in hw_heartbeat_ms before this timeout.
146 last_heartbeat
= ktime_sub(virt_timeout
, ms_to_ktime(hw_heartbeat_ms
));
147 latest_heartbeat
= ktime_sub(last_heartbeat
, ktime_get());
148 if (ktime_before(latest_heartbeat
, keepalive_interval
))
149 return latest_heartbeat
;
150 return keepalive_interval
;
153 static inline void watchdog_update_worker(struct watchdog_device
*wdd
)
155 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
157 if (watchdog_need_worker(wdd
)) {
158 ktime_t t
= watchdog_next_keepalive(wdd
);
161 hrtimer_start(&wd_data
->timer
, t
, HRTIMER_MODE_REL
);
163 hrtimer_cancel(&wd_data
->timer
);
167 static int __watchdog_ping(struct watchdog_device
*wdd
)
169 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
170 ktime_t earliest_keepalive
, now
;
173 earliest_keepalive
= ktime_add(wd_data
->last_hw_keepalive
,
174 ms_to_ktime(wdd
->min_hw_heartbeat_ms
));
177 if (ktime_after(earliest_keepalive
, now
)) {
178 hrtimer_start(&wd_data
->timer
,
179 ktime_sub(earliest_keepalive
, now
),
184 wd_data
->last_hw_keepalive
= now
;
187 err
= wdd
->ops
->ping(wdd
); /* ping the watchdog */
189 err
= wdd
->ops
->start(wdd
); /* restart watchdog */
191 watchdog_update_worker(wdd
);
197 * watchdog_ping: ping the watchdog.
198 * @wdd: the watchdog device to ping
200 * The caller must hold wd_data->lock.
202 * If the watchdog has no own ping operation then it needs to be
203 * restarted via the start operation. This wrapper function does
205 * We only ping when the watchdog device is running.
208 static int watchdog_ping(struct watchdog_device
*wdd
)
210 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
212 if (!watchdog_active(wdd
) && !watchdog_hw_running(wdd
))
215 set_bit(_WDOG_KEEPALIVE
, &wd_data
->status
);
217 wd_data
->last_keepalive
= ktime_get();
218 return __watchdog_ping(wdd
);
221 static bool watchdog_worker_should_ping(struct watchdog_core_data
*wd_data
)
223 struct watchdog_device
*wdd
= wd_data
->wdd
;
228 if (watchdog_active(wdd
))
231 return watchdog_hw_running(wdd
) && !watchdog_past_open_deadline(wd_data
);
234 static void watchdog_ping_work(struct kthread_work
*work
)
236 struct watchdog_core_data
*wd_data
;
238 wd_data
= container_of(work
, struct watchdog_core_data
, work
);
240 mutex_lock(&wd_data
->lock
);
241 if (watchdog_worker_should_ping(wd_data
))
242 __watchdog_ping(wd_data
->wdd
);
243 mutex_unlock(&wd_data
->lock
);
246 static enum hrtimer_restart
watchdog_timer_expired(struct hrtimer
*timer
)
248 struct watchdog_core_data
*wd_data
;
250 wd_data
= container_of(timer
, struct watchdog_core_data
, timer
);
252 kthread_queue_work(watchdog_kworker
, &wd_data
->work
);
253 return HRTIMER_NORESTART
;
257 * watchdog_start: wrapper to start the watchdog.
258 * @wdd: the watchdog device to start
260 * The caller must hold wd_data->lock.
262 * Start the watchdog if it is not active and mark it active.
263 * This function returns zero on success or a negative errno code for
267 static int watchdog_start(struct watchdog_device
*wdd
)
269 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
273 if (watchdog_active(wdd
))
276 set_bit(_WDOG_KEEPALIVE
, &wd_data
->status
);
278 started_at
= ktime_get();
279 if (watchdog_hw_running(wdd
) && wdd
->ops
->ping
)
280 err
= wdd
->ops
->ping(wdd
);
282 err
= wdd
->ops
->start(wdd
);
284 set_bit(WDOG_ACTIVE
, &wdd
->status
);
285 wd_data
->last_keepalive
= started_at
;
286 watchdog_update_worker(wdd
);
293 * watchdog_stop: wrapper to stop the watchdog.
294 * @wdd: the watchdog device to stop
296 * The caller must hold wd_data->lock.
298 * Stop the watchdog if it is still active and unmark it active.
299 * This function returns zero on success or a negative errno code for
301 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
304 static int watchdog_stop(struct watchdog_device
*wdd
)
308 if (!watchdog_active(wdd
))
311 if (test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
)) {
312 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
317 if (wdd
->ops
->stop
) {
318 clear_bit(WDOG_HW_RUNNING
, &wdd
->status
);
319 err
= wdd
->ops
->stop(wdd
);
321 set_bit(WDOG_HW_RUNNING
, &wdd
->status
);
325 clear_bit(WDOG_ACTIVE
, &wdd
->status
);
326 watchdog_update_worker(wdd
);
333 * watchdog_get_status: wrapper to get the watchdog status
334 * @wdd: the watchdog device to get the status from
336 * The caller must hold wd_data->lock.
338 * Get the watchdog's status flags.
341 static unsigned int watchdog_get_status(struct watchdog_device
*wdd
)
343 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
346 if (wdd
->ops
->status
)
347 status
= wdd
->ops
->status(wdd
);
349 status
= wdd
->bootstatus
& (WDIOF_CARDRESET
|
357 if (test_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
))
358 status
|= WDIOF_MAGICCLOSE
;
360 if (test_and_clear_bit(_WDOG_KEEPALIVE
, &wd_data
->status
))
361 status
|= WDIOF_KEEPALIVEPING
;
367 * watchdog_set_timeout: set the watchdog timer timeout
368 * @wdd: the watchdog device to set the timeout for
369 * @timeout: timeout to set in seconds
371 * The caller must hold wd_data->lock.
374 static int watchdog_set_timeout(struct watchdog_device
*wdd
,
375 unsigned int timeout
)
379 if (!(wdd
->info
->options
& WDIOF_SETTIMEOUT
))
382 if (watchdog_timeout_invalid(wdd
, timeout
))
385 if (wdd
->ops
->set_timeout
) {
386 err
= wdd
->ops
->set_timeout(wdd
, timeout
);
388 wdd
->timeout
= timeout
;
389 /* Disable pretimeout if it doesn't fit the new timeout */
390 if (wdd
->pretimeout
>= wdd
->timeout
)
394 watchdog_update_worker(wdd
);
400 * watchdog_set_pretimeout: set the watchdog timer pretimeout
401 * @wdd: the watchdog device to set the timeout for
402 * @timeout: pretimeout to set in seconds
405 static int watchdog_set_pretimeout(struct watchdog_device
*wdd
,
406 unsigned int timeout
)
410 if (!(wdd
->info
->options
& WDIOF_PRETIMEOUT
))
413 if (watchdog_pretimeout_invalid(wdd
, timeout
))
416 if (wdd
->ops
->set_pretimeout
)
417 err
= wdd
->ops
->set_pretimeout(wdd
, timeout
);
419 wdd
->pretimeout
= timeout
;
425 * watchdog_get_timeleft: wrapper to get the time left before a reboot
426 * @wdd: the watchdog device to get the remaining time from
427 * @timeleft: the time that's left
429 * The caller must hold wd_data->lock.
431 * Get the time before a watchdog will reboot (if not pinged).
434 static int watchdog_get_timeleft(struct watchdog_device
*wdd
,
435 unsigned int *timeleft
)
439 if (!wdd
->ops
->get_timeleft
)
442 *timeleft
= wdd
->ops
->get_timeleft(wdd
);
447 #ifdef CONFIG_WATCHDOG_SYSFS
448 static ssize_t
nowayout_show(struct device
*dev
, struct device_attribute
*attr
,
451 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
453 return sprintf(buf
, "%d\n", !!test_bit(WDOG_NO_WAY_OUT
, &wdd
->status
));
455 static DEVICE_ATTR_RO(nowayout
);
457 static ssize_t
status_show(struct device
*dev
, struct device_attribute
*attr
,
460 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
461 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
464 mutex_lock(&wd_data
->lock
);
465 status
= watchdog_get_status(wdd
);
466 mutex_unlock(&wd_data
->lock
);
468 return sprintf(buf
, "0x%x\n", status
);
470 static DEVICE_ATTR_RO(status
);
472 static ssize_t
bootstatus_show(struct device
*dev
,
473 struct device_attribute
*attr
, char *buf
)
475 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
477 return sprintf(buf
, "%u\n", wdd
->bootstatus
);
479 static DEVICE_ATTR_RO(bootstatus
);
481 static ssize_t
timeleft_show(struct device
*dev
, struct device_attribute
*attr
,
484 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
485 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
489 mutex_lock(&wd_data
->lock
);
490 status
= watchdog_get_timeleft(wdd
, &val
);
491 mutex_unlock(&wd_data
->lock
);
493 status
= sprintf(buf
, "%u\n", val
);
497 static DEVICE_ATTR_RO(timeleft
);
499 static ssize_t
timeout_show(struct device
*dev
, struct device_attribute
*attr
,
502 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
504 return sprintf(buf
, "%u\n", wdd
->timeout
);
506 static DEVICE_ATTR_RO(timeout
);
508 static ssize_t
pretimeout_show(struct device
*dev
,
509 struct device_attribute
*attr
, char *buf
)
511 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
513 return sprintf(buf
, "%u\n", wdd
->pretimeout
);
515 static DEVICE_ATTR_RO(pretimeout
);
517 static ssize_t
identity_show(struct device
*dev
, struct device_attribute
*attr
,
520 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
522 return sprintf(buf
, "%s\n", wdd
->info
->identity
);
524 static DEVICE_ATTR_RO(identity
);
526 static ssize_t
state_show(struct device
*dev
, struct device_attribute
*attr
,
529 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
531 if (watchdog_active(wdd
))
532 return sprintf(buf
, "active\n");
534 return sprintf(buf
, "inactive\n");
536 static DEVICE_ATTR_RO(state
);
538 static ssize_t
pretimeout_available_governors_show(struct device
*dev
,
539 struct device_attribute
*attr
, char *buf
)
541 return watchdog_pretimeout_available_governors_get(buf
);
543 static DEVICE_ATTR_RO(pretimeout_available_governors
);
545 static ssize_t
pretimeout_governor_show(struct device
*dev
,
546 struct device_attribute
*attr
,
549 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
551 return watchdog_pretimeout_governor_get(wdd
, buf
);
554 static ssize_t
pretimeout_governor_store(struct device
*dev
,
555 struct device_attribute
*attr
,
556 const char *buf
, size_t count
)
558 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
559 int ret
= watchdog_pretimeout_governor_set(wdd
, buf
);
566 static DEVICE_ATTR_RW(pretimeout_governor
);
568 static umode_t
wdt_is_visible(struct kobject
*kobj
, struct attribute
*attr
,
571 struct device
*dev
= container_of(kobj
, struct device
, kobj
);
572 struct watchdog_device
*wdd
= dev_get_drvdata(dev
);
573 umode_t mode
= attr
->mode
;
575 if (attr
== &dev_attr_timeleft
.attr
&& !wdd
->ops
->get_timeleft
)
577 else if (attr
== &dev_attr_pretimeout
.attr
&&
578 !(wdd
->info
->options
& WDIOF_PRETIMEOUT
))
580 else if ((attr
== &dev_attr_pretimeout_governor
.attr
||
581 attr
== &dev_attr_pretimeout_available_governors
.attr
) &&
582 (!(wdd
->info
->options
& WDIOF_PRETIMEOUT
) ||
583 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV
)))
588 static struct attribute
*wdt_attrs
[] = {
589 &dev_attr_state
.attr
,
590 &dev_attr_identity
.attr
,
591 &dev_attr_timeout
.attr
,
592 &dev_attr_pretimeout
.attr
,
593 &dev_attr_timeleft
.attr
,
594 &dev_attr_bootstatus
.attr
,
595 &dev_attr_status
.attr
,
596 &dev_attr_nowayout
.attr
,
597 &dev_attr_pretimeout_governor
.attr
,
598 &dev_attr_pretimeout_available_governors
.attr
,
602 static const struct attribute_group wdt_group
= {
604 .is_visible
= wdt_is_visible
,
606 __ATTRIBUTE_GROUPS(wdt
);
608 #define wdt_groups NULL
612 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
613 * @wdd: the watchdog device to do the ioctl on
614 * @cmd: watchdog command
615 * @arg: argument pointer
617 * The caller must hold wd_data->lock.
620 static int watchdog_ioctl_op(struct watchdog_device
*wdd
, unsigned int cmd
,
623 if (!wdd
->ops
->ioctl
)
626 return wdd
->ops
->ioctl(wdd
, cmd
, arg
);
630 * watchdog_write: writes to the watchdog.
631 * @file: file from VFS
632 * @data: user address of data
633 * @len: length of data
634 * @ppos: pointer to the file offset
636 * A write to a watchdog device is defined as a keepalive ping.
637 * Writing the magic 'V' sequence allows the next close to turn
638 * off the watchdog (if 'nowayout' is not set).
641 static ssize_t
watchdog_write(struct file
*file
, const char __user
*data
,
642 size_t len
, loff_t
*ppos
)
644 struct watchdog_core_data
*wd_data
= file
->private_data
;
645 struct watchdog_device
*wdd
;
654 * Note: just in case someone wrote the magic character
657 clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
659 /* scan to see whether or not we got the magic character */
660 for (i
= 0; i
!= len
; i
++) {
661 if (get_user(c
, data
+ i
))
664 set_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
);
667 /* someone wrote to us, so we send the watchdog a keepalive ping */
670 mutex_lock(&wd_data
->lock
);
673 err
= watchdog_ping(wdd
);
674 mutex_unlock(&wd_data
->lock
);
683 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
684 * @file: file handle to the device
685 * @cmd: watchdog command
686 * @arg: argument pointer
688 * The watchdog API defines a common set of functions for all watchdogs
689 * according to their available features.
692 static long watchdog_ioctl(struct file
*file
, unsigned int cmd
,
695 struct watchdog_core_data
*wd_data
= file
->private_data
;
696 void __user
*argp
= (void __user
*)arg
;
697 struct watchdog_device
*wdd
;
698 int __user
*p
= argp
;
702 mutex_lock(&wd_data
->lock
);
710 err
= watchdog_ioctl_op(wdd
, cmd
, arg
);
711 if (err
!= -ENOIOCTLCMD
)
715 case WDIOC_GETSUPPORT
:
716 err
= copy_to_user(argp
, wdd
->info
,
717 sizeof(struct watchdog_info
)) ? -EFAULT
: 0;
719 case WDIOC_GETSTATUS
:
720 val
= watchdog_get_status(wdd
);
721 err
= put_user(val
, p
);
723 case WDIOC_GETBOOTSTATUS
:
724 err
= put_user(wdd
->bootstatus
, p
);
726 case WDIOC_SETOPTIONS
:
727 if (get_user(val
, p
)) {
731 if (val
& WDIOS_DISABLECARD
) {
732 err
= watchdog_stop(wdd
);
736 if (val
& WDIOS_ENABLECARD
)
737 err
= watchdog_start(wdd
);
739 case WDIOC_KEEPALIVE
:
740 if (!(wdd
->info
->options
& WDIOF_KEEPALIVEPING
)) {
744 err
= watchdog_ping(wdd
);
746 case WDIOC_SETTIMEOUT
:
747 if (get_user(val
, p
)) {
751 err
= watchdog_set_timeout(wdd
, val
);
754 /* If the watchdog is active then we send a keepalive ping
755 * to make sure that the watchdog keep's running (and if
756 * possible that it takes the new timeout) */
757 err
= watchdog_ping(wdd
);
761 case WDIOC_GETTIMEOUT
:
762 /* timeout == 0 means that we don't know the timeout */
763 if (wdd
->timeout
== 0) {
767 err
= put_user(wdd
->timeout
, p
);
769 case WDIOC_GETTIMELEFT
:
770 err
= watchdog_get_timeleft(wdd
, &val
);
773 err
= put_user(val
, p
);
775 case WDIOC_SETPRETIMEOUT
:
776 if (get_user(val
, p
)) {
780 err
= watchdog_set_pretimeout(wdd
, val
);
782 case WDIOC_GETPRETIMEOUT
:
783 err
= put_user(wdd
->pretimeout
, p
);
791 mutex_unlock(&wd_data
->lock
);
796 * watchdog_open: open the /dev/watchdog* devices.
797 * @inode: inode of device
798 * @file: file handle to device
800 * When the /dev/watchdog* device gets opened, we start the watchdog.
801 * Watch out: the /dev/watchdog device is single open, so we make sure
802 * it can only be opened once.
805 static int watchdog_open(struct inode
*inode
, struct file
*file
)
807 struct watchdog_core_data
*wd_data
;
808 struct watchdog_device
*wdd
;
812 /* Get the corresponding watchdog device */
813 if (imajor(inode
) == MISC_MAJOR
)
814 wd_data
= old_wd_data
;
816 wd_data
= container_of(inode
->i_cdev
, struct watchdog_core_data
,
819 /* the watchdog is single open! */
820 if (test_and_set_bit(_WDOG_DEV_OPEN
, &wd_data
->status
))
826 * If the /dev/watchdog device is open, we don't want the module
829 hw_running
= watchdog_hw_running(wdd
);
830 if (!hw_running
&& !try_module_get(wdd
->ops
->owner
)) {
835 err
= watchdog_start(wdd
);
839 file
->private_data
= wd_data
;
842 kref_get(&wd_data
->kref
);
845 * open_timeout only applies for the first open from
846 * userspace. Set open_deadline to infinity so that the kernel
847 * will take care of an always-running hardware watchdog in
848 * case the device gets magic-closed or WDIOS_DISABLECARD is
851 wd_data
->open_deadline
= KTIME_MAX
;
853 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
854 return stream_open(inode
, file
);
857 module_put(wd_data
->wdd
->ops
->owner
);
859 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
863 static void watchdog_core_data_release(struct kref
*kref
)
865 struct watchdog_core_data
*wd_data
;
867 wd_data
= container_of(kref
, struct watchdog_core_data
, kref
);
873 * watchdog_release: release the watchdog device.
874 * @inode: inode of device
875 * @file: file handle to device
877 * This is the code for when /dev/watchdog gets closed. We will only
878 * stop the watchdog when we have received the magic char (and nowayout
879 * was not set), else the watchdog will keep running.
882 static int watchdog_release(struct inode
*inode
, struct file
*file
)
884 struct watchdog_core_data
*wd_data
= file
->private_data
;
885 struct watchdog_device
*wdd
;
889 mutex_lock(&wd_data
->lock
);
896 * We only stop the watchdog if we received the magic character
897 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
898 * watchdog_stop will fail.
900 if (!test_bit(WDOG_ACTIVE
, &wdd
->status
))
902 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE
, &wd_data
->status
) ||
903 !(wdd
->info
->options
& WDIOF_MAGICCLOSE
))
904 err
= watchdog_stop(wdd
);
906 /* If the watchdog was not stopped, send a keepalive ping */
908 pr_crit("watchdog%d: watchdog did not stop!\n", wdd
->id
);
912 watchdog_update_worker(wdd
);
914 /* make sure that /dev/watchdog can be re-opened */
915 clear_bit(_WDOG_DEV_OPEN
, &wd_data
->status
);
918 running
= wdd
&& watchdog_hw_running(wdd
);
919 mutex_unlock(&wd_data
->lock
);
921 * Allow the owner module to be unloaded again unless the watchdog
922 * is still running. If the watchdog is still running, it can not
923 * be stopped, and its driver must not be unloaded.
926 module_put(wd_data
->cdev
.owner
);
927 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
932 static const struct file_operations watchdog_fops
= {
933 .owner
= THIS_MODULE
,
934 .write
= watchdog_write
,
935 .unlocked_ioctl
= watchdog_ioctl
,
936 .open
= watchdog_open
,
937 .release
= watchdog_release
,
940 static struct miscdevice watchdog_miscdev
= {
941 .minor
= WATCHDOG_MINOR
,
943 .fops
= &watchdog_fops
,
947 * watchdog_cdev_register: register watchdog character device
948 * @wdd: watchdog device
949 * @devno: character device number
951 * Register a watchdog character device including handling the legacy
952 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
953 * thus we set it up like that.
956 static int watchdog_cdev_register(struct watchdog_device
*wdd
, dev_t devno
)
958 struct watchdog_core_data
*wd_data
;
961 wd_data
= kzalloc(sizeof(struct watchdog_core_data
), GFP_KERNEL
);
964 kref_init(&wd_data
->kref
);
965 mutex_init(&wd_data
->lock
);
968 wdd
->wd_data
= wd_data
;
970 if (IS_ERR_OR_NULL(watchdog_kworker
))
973 kthread_init_work(&wd_data
->work
, watchdog_ping_work
);
974 hrtimer_init(&wd_data
->timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
975 wd_data
->timer
.function
= watchdog_timer_expired
;
978 old_wd_data
= wd_data
;
979 watchdog_miscdev
.parent
= wdd
->parent
;
980 err
= misc_register(&watchdog_miscdev
);
982 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
983 wdd
->info
->identity
, WATCHDOG_MINOR
, err
);
985 pr_err("%s: a legacy watchdog module is probably present.\n",
986 wdd
->info
->identity
);
993 /* Fill in the data structures */
994 cdev_init(&wd_data
->cdev
, &watchdog_fops
);
995 wd_data
->cdev
.owner
= wdd
->ops
->owner
;
998 err
= cdev_add(&wd_data
->cdev
, devno
, 1);
1000 pr_err("watchdog%d unable to add device %d:%d\n",
1001 wdd
->id
, MAJOR(watchdog_devt
), wdd
->id
);
1003 misc_deregister(&watchdog_miscdev
);
1005 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
1010 /* Record time of most recent heartbeat as 'just before now'. */
1011 wd_data
->last_hw_keepalive
= ktime_sub(ktime_get(), 1);
1012 watchdog_set_open_deadline(wd_data
);
1015 * If the watchdog is running, prevent its driver from being unloaded,
1016 * and schedule an immediate ping.
1018 if (watchdog_hw_running(wdd
)) {
1019 __module_get(wdd
->ops
->owner
);
1020 kref_get(&wd_data
->kref
);
1021 if (handle_boot_enabled
)
1022 hrtimer_start(&wd_data
->timer
, 0, HRTIMER_MODE_REL
);
1024 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1032 * watchdog_cdev_unregister: unregister watchdog character device
1033 * @watchdog: watchdog device
1035 * Unregister watchdog character device and if needed the legacy
1036 * /dev/watchdog device.
1039 static void watchdog_cdev_unregister(struct watchdog_device
*wdd
)
1041 struct watchdog_core_data
*wd_data
= wdd
->wd_data
;
1043 cdev_del(&wd_data
->cdev
);
1045 misc_deregister(&watchdog_miscdev
);
1049 if (watchdog_active(wdd
) &&
1050 test_bit(WDOG_STOP_ON_UNREGISTER
, &wdd
->status
)) {
1054 mutex_lock(&wd_data
->lock
);
1055 wd_data
->wdd
= NULL
;
1056 wdd
->wd_data
= NULL
;
1057 mutex_unlock(&wd_data
->lock
);
1059 hrtimer_cancel(&wd_data
->timer
);
1060 kthread_cancel_work_sync(&wd_data
->work
);
1062 kref_put(&wd_data
->kref
, watchdog_core_data_release
);
1065 static struct class watchdog_class
= {
1067 .owner
= THIS_MODULE
,
1068 .dev_groups
= wdt_groups
,
1071 static int watchdog_reboot_notifier(struct notifier_block
*nb
,
1072 unsigned long code
, void *data
)
1074 struct watchdog_device
*wdd
;
1076 wdd
= container_of(nb
, struct watchdog_device
, reboot_nb
);
1077 if (code
== SYS_DOWN
|| code
== SYS_HALT
) {
1078 if (watchdog_active(wdd
)) {
1081 ret
= wdd
->ops
->stop(wdd
);
1091 * watchdog_dev_register: register a watchdog device
1092 * @wdd: watchdog device
1094 * Register a watchdog device including handling the legacy
1095 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1096 * thus we set it up like that.
1099 int watchdog_dev_register(struct watchdog_device
*wdd
)
1105 devno
= MKDEV(MAJOR(watchdog_devt
), wdd
->id
);
1107 ret
= watchdog_cdev_register(wdd
, devno
);
1111 dev
= device_create_with_groups(&watchdog_class
, wdd
->parent
,
1112 devno
, wdd
, wdd
->groups
,
1113 "watchdog%d", wdd
->id
);
1115 watchdog_cdev_unregister(wdd
);
1116 return PTR_ERR(dev
);
1119 ret
= watchdog_register_pretimeout(wdd
);
1121 device_destroy(&watchdog_class
, devno
);
1122 watchdog_cdev_unregister(wdd
);
1126 if (test_bit(WDOG_STOP_ON_REBOOT
, &wdd
->status
)) {
1127 wdd
->reboot_nb
.notifier_call
= watchdog_reboot_notifier
;
1129 ret
= devm_register_reboot_notifier(dev
, &wdd
->reboot_nb
);
1131 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
1133 watchdog_dev_unregister(wdd
);
1141 * watchdog_dev_unregister: unregister a watchdog device
1142 * @watchdog: watchdog device
1144 * Unregister watchdog device and if needed the legacy
1145 * /dev/watchdog device.
1148 void watchdog_dev_unregister(struct watchdog_device
*wdd
)
1150 watchdog_unregister_pretimeout(wdd
);
1151 device_destroy(&watchdog_class
, wdd
->wd_data
->cdev
.dev
);
1152 watchdog_cdev_unregister(wdd
);
1156 * watchdog_dev_init: init dev part of watchdog core
1158 * Allocate a range of chardev nodes to use for watchdog devices
1161 int __init
watchdog_dev_init(void)
1164 struct sched_param param
= {.sched_priority
= MAX_RT_PRIO
- 1,};
1166 watchdog_kworker
= kthread_create_worker(0, "watchdogd");
1167 if (IS_ERR(watchdog_kworker
)) {
1168 pr_err("Failed to create watchdog kworker\n");
1169 return PTR_ERR(watchdog_kworker
);
1171 sched_setscheduler(watchdog_kworker
->task
, SCHED_FIFO
, ¶m
);
1173 err
= class_register(&watchdog_class
);
1175 pr_err("couldn't register class\n");
1179 err
= alloc_chrdev_region(&watchdog_devt
, 0, MAX_DOGS
, "watchdog");
1181 pr_err("watchdog: unable to allocate char dev region\n");
1188 class_unregister(&watchdog_class
);
1190 kthread_destroy_worker(watchdog_kworker
);
1195 * watchdog_dev_exit: exit dev part of watchdog core
1197 * Release the range of chardev nodes used for watchdog devices
1200 void __exit
watchdog_dev_exit(void)
1202 unregister_chrdev_region(watchdog_devt
, MAX_DOGS
);
1203 class_unregister(&watchdog_class
);
1204 kthread_destroy_worker(watchdog_kworker
);
1207 module_param(handle_boot_enabled
, bool, 0444);
1208 MODULE_PARM_DESC(handle_boot_enabled
,
1209 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1210 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED
)) ")");
1212 module_param(open_timeout
, uint
, 0644);
1213 MODULE_PARM_DESC(open_timeout
,
1214 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1215 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT
) ")");