12  *	by all the watchdog timer drivers.
15  *	misc device: /dev/watchdog.
43 #include <linux/watchdog.h>	/* For watchdog specific items */
50  * struct watchdog_core_data - watchdog core internal data
51  * @dev:	The watchdog's internal device
52  * @cdev:	The watchdog's Character device.
53  * @wdd:	Pointer to watchdog device.
54  * @lock:	Lock for watchdog core.
55  * @status:	Watchdog core internal status bits.
73 /* the dev_t structure to store the dynamically allocated watchdog devices */
75 /* Reference to watchdog device behind /dev/watchdog */
105 	 * - Userspace activated the watchdog.  in watchdog_need_worker()
111 	 * Alternatively, if userspace has not opened the watchdog  in watchdog_need_worker()
112 	 * device, we take care of feeding the watchdog if it is  in watchdog_need_worker()
138 	 * To ensure that the watchdog times out wdd->timeout seconds  in watchdog_next_keepalive()
184 		err = wdd->ops->ping(wdd);  /* ping the watchdog */  in __watchdog_ping()
186 		err = wdd->ops->start(wdd); /* restart watchdog */  in __watchdog_ping()
194  *	watchdog_ping: ping the watchdog.
195  *	@wdd: the watchdog device to ping
199  *	If the watchdog has no own ping operation then it needs to be
202  *	We only ping when the watchdog device is running.
254  *	watchdog_start: wrapper to start the watchdog.
255  *	@wdd: the watchdog device to start
259  *	Start the watchdog if it is not active and mark it active.
294  *	watchdog_stop: wrapper to stop the watchdog.
295  *	@wdd: the watchdog device to stop
299  *	Stop the watchdog if it is still active and unmark it active.
302  *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
313 		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",  in watchdog_stop()
334  *	watchdog_get_status: wrapper to get the watchdog status
335  *	@wdd: the watchdog device to get the status from
339  *	Get the watchdog's status flags.
368  *	watchdog_set_timeout: set the watchdog timer timeout
369  *	@wdd: the watchdog device to set the timeout for
401  *	watchdog_set_pretimeout: set the watchdog timer pretimeout
402  *	@wdd: the watchdog device to set the timeout for
427  *	@wdd: the watchdog device to get the remaining time from
432  *	Get the time before a watchdog will reboot (if not pinged).
632  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
633  *	@wdd: the watchdog device to do the ioctl on
634  *	@cmd: watchdog command
650  *	watchdog_write: writes to the watchdog.
656  *	A write to a watchdog device is defined as a keepalive ping.
658  *	off the watchdog (if 'nowayout' is not set).
687 	/* someone wrote to us, so we send the watchdog a keepalive ping */  in watchdog_write()
703  *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
705  *	@cmd: watchdog command
708  *	The watchdog API defines a common set of functions for all watchdogs
774 		/* If the watchdog is active then we send a keepalive ping  in watchdog_ioctl()
775 		 * to make sure that the watchdog keep's running (and if  in watchdog_ioctl()
816  *	watchdog_open: open the /dev/watchdog* devices.
820  *	When the /dev/watchdog* device gets opened, we start the watchdog.
821  *	Watch out: the /dev/watchdog device is single open, so we make sure
832 	/* Get the corresponding watchdog device */  in watchdog_open()
839 	/* the watchdog is single open! */  in watchdog_open()
846 	 * If the /dev/watchdog device is open, we don't want the module  in watchdog_open()
867 	 * will take care of an always-running hardware watchdog in  in watchdog_open()
873 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */  in watchdog_open()
893  *	watchdog_release: release the watchdog device.
897  *	This is the code for when /dev/watchdog gets closed. We will only
898  *	stop the watchdog when we have received the magic char (and nowayout
899  *	was not set), else the watchdog will keep running.
916 	 * We only stop the watchdog if we received the magic character  in watchdog_release()
926 	/* If the watchdog was not stopped, send a keepalive ping */  in watchdog_release()
928 		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);  in watchdog_release()
934 	/* make sure that /dev/watchdog can be re-opened */  in watchdog_release()
941 	 * Allow the owner module to be unloaded again unless the watchdog  in watchdog_release()
942 	 * is still running. If the watchdog is still running, it can not  in watchdog_release()
963 	.name		= "watchdog",
968 	.name =		"watchdog",
974  *	watchdog_cdev_register: register watchdog character device
975  *	@wdd: watchdog device
977  *	Register a watchdog character device including handling the legacy
978  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
1007 	dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);  in watchdog_cdev_register()
1021 				pr_err("%s: a legacy watchdog module is probably present.\n",  in watchdog_cdev_register()
1035 		pr_err("watchdog%d unable to add device %d:%d\n",  in watchdog_cdev_register()
1052 	 * If the watchdog is running, prevent its driver from being unloaded,  in watchdog_cdev_register()
1062 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",  in watchdog_cdev_register()
1070  *	watchdog_cdev_unregister: unregister watchdog character device
1071  *	@watchdog: watchdog device
1073  *	Unregister watchdog character device and if needed the legacy
1074  *	/dev/watchdog device.
1104  *	watchdog_dev_register: register a watchdog device
1105  *	@wdd: watchdog device
1107  *	Register a watchdog device including handling the legacy
1108  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
1128  *	watchdog_dev_unregister: unregister a watchdog device
1129  *	@watchdog: watchdog device
1131  *	Unregister watchdog device and if needed the legacy
1132  *	/dev/watchdog device.
1142  *	watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog
1143  *	@wdd: watchdog device
1146  *	Adjusts the last known HW keepalive time for a watchdog timer.
1147  *	This is needed if the watchdog is already running when the probe
1149  *	function must be called immediately after watchdog registration,
1172  *	watchdog_dev_init: init dev part of watchdog core
1174  *	Allocate a range of chardev nodes to use for watchdog devices
1183 		pr_err("Failed to create watchdog kworker\n");  in watchdog_dev_init()
1194 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");  in watchdog_dev_init()
1196 		pr_err("watchdog: unable to allocate char dev region\n");  in watchdog_dev_init()
1210  *	watchdog_dev_exit: exit dev part of watchdog core
1212  *	Release the range of chardev nodes used for watchdog devices
1224 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1229 …"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (defaul…