13  *	by all the watchdog timer drivers.
16  *	misc device: /dev/watchdog.
44 #include <linux/watchdog.h>	/* For watchdog specific items */
50 /* the dev_t structure to store the dynamically allocated watchdog devices */
52 /* Reference to watchdog device behind /dev/watchdog */
82 	 * - Userspace activated the watchdog.  in watchdog_need_worker()
88 	 * Alternatively, if userspace has not opened the watchdog  in watchdog_need_worker()
89 	 * device, we take care of feeding the watchdog if it is  in watchdog_need_worker()
115 	 * To ensure that the watchdog times out wdd->timeout seconds  in watchdog_next_keepalive()
161 		err = wdd->ops->ping(wdd);  /* ping the watchdog */  in __watchdog_ping()
163 		err = wdd->ops->start(wdd); /* restart watchdog */  in __watchdog_ping()
174  *	watchdog_ping: ping the watchdog.
175  *	@wdd: the watchdog device to ping
179  *	If the watchdog has no own ping operation then it needs to be
182  *	We only ping when the watchdog device is running.
234  *	watchdog_start: wrapper to start the watchdog.
235  *	@wdd: the watchdog device to start
239  *	Start the watchdog if it is not active and mark it active.
277  *	watchdog_stop: wrapper to stop the watchdog.
278  *	@wdd: the watchdog device to stop
282  *	Stop the watchdog if it is still active and unmark it active.
285  *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
296 		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",  in watchdog_stop()
318  *	watchdog_get_status: wrapper to get the watchdog status
319  *	@wdd: the watchdog device to get the status from
323  *	Get the watchdog's status flags.
355  *	watchdog_set_timeout: set the watchdog timer timeout
356  *	@wdd: the watchdog device to set the timeout for
388  *	watchdog_set_pretimeout: set the watchdog timer pretimeout
389  *	@wdd: the watchdog device to set the timeout for
414  *	@wdd: the watchdog device to get the remaining time from
419  *	Get the time before a watchdog will reboot (if not pinged).
638  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
639  *	@wdd: the watchdog device to do the ioctl on
640  *	@cmd: watchdog command
656  *	watchdog_write: writes to the watchdog.
662  *	A write to a watchdog device is defined as a keepalive ping.
664  *	off the watchdog (if 'nowayout' is not set).
693 	/* someone wrote to us, so we send the watchdog a keepalive ping */  in watchdog_write()
709  *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
711  *	@cmd: watchdog command
714  *	The watchdog API defines a common set of functions for all watchdogs
780 		/* If the watchdog is active then we send a keepalive ping  in watchdog_ioctl()
781 		 * to make sure that the watchdog keep's running (and if  in watchdog_ioctl()
822  *	watchdog_open: open the /dev/watchdog* devices.
826  *	When the /dev/watchdog* device gets opened, we start the watchdog.
827  *	Watch out: the /dev/watchdog device is single open, so we make sure
838 	/* Get the corresponding watchdog device */  in watchdog_open()
845 	/* the watchdog is single open! */  in watchdog_open()
852 	 * If the /dev/watchdog device is open, we don't want the module  in watchdog_open()
873 	 * will take care of an always-running hardware watchdog in  in watchdog_open()
879 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */  in watchdog_open()
899  *	watchdog_release: release the watchdog device.
903  *	This is the code for when /dev/watchdog gets closed. We will only
904  *	stop the watchdog when we have received the magic char (and nowayout
905  *	was not set), else the watchdog will keep running.
922 	 * We only stop the watchdog if we received the magic character  in watchdog_release()
932 	/* If the watchdog was not stopped, send a keepalive ping */  in watchdog_release()
934 		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);  in watchdog_release()
940 	/* make sure that /dev/watchdog can be re-opened */  in watchdog_release()
947 	 * Allow the owner module to be unloaded again unless the watchdog  in watchdog_release()
948 	 * is still running. If the watchdog is still running, it can not  in watchdog_release()
969 	.name		= "watchdog",
974 	.name =		"watchdog",
980  *	watchdog_cdev_register: register watchdog character device
981  *	@wdd: watchdog device
983  *	Register a watchdog character device including handling the legacy
984  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
1013 	dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);  in watchdog_cdev_register()
1028 				pr_err("%s: a legacy watchdog module is probably present.\n",  in watchdog_cdev_register()
1042 		pr_err("watchdog%d unable to add device %d:%d\n",  in watchdog_cdev_register()
1059 	 * If the watchdog is running, prevent its driver from being unloaded,  in watchdog_cdev_register()
1069 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",  in watchdog_cdev_register()
1077  *	watchdog_cdev_unregister: unregister watchdog character device
1078  *	@watchdog: watchdog device
1080  *	Unregister watchdog character device and if needed the legacy
1081  *	/dev/watchdog device.
1113  *	watchdog_dev_register: register a watchdog device
1114  *	@wdd: watchdog device
1116  *	Register a watchdog device including handling the legacy
1117  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
1137  *	watchdog_dev_unregister: unregister a watchdog device
1138  *	@watchdog: watchdog device
1140  *	Unregister watchdog device and if needed the legacy
1141  *	/dev/watchdog device.
1151  *	watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog
1152  *	@wdd: watchdog device
1155  *	Adjusts the last known HW keepalive time for a watchdog timer.
1156  *	This is needed if the watchdog is already running when the probe
1158  *	function must be called immediately after watchdog registration,
1184  *	watchdog_dev_init: init dev part of watchdog core
1186  *	Allocate a range of chardev nodes to use for watchdog devices
1195 		pr_err("Failed to create watchdog kworker\n");  in watchdog_dev_init()
1206 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");  in watchdog_dev_init()
1208 		pr_err("watchdog: unable to allocate char dev region\n");  in watchdog_dev_init()
1222  *	watchdog_dev_exit: exit dev part of watchdog core
1224  *	Release the range of chardev nodes used for watchdog devices
1252 	 * make sure that watchdog worker will not kick in when the wdog is  in watchdog_dev_suspend()
1283 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1288 …"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (defaul…