linux/include/linux/watchdog.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 *	Generic watchdog defines. Derived from..
 *
 * Berkshire PC Watchdog Defines
 * by Ken Hollis <[email protected]>
 *
 */
#ifndef _LINUX_WATCHDOG_H
#define _LINUX_WATCHDOG_H


#include <linux/bitops.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/notifier.h>
#include <uapi/linux/watchdog.h>

struct watchdog_ops;
struct watchdog_device;
struct watchdog_core_data;
struct watchdog_governor;

/** struct watchdog_ops - The watchdog-devices operations
 *
 * @owner:	The module owner.
 * @start:	The routine for starting the watchdog device.
 * @stop:	The routine for stopping the watchdog device.
 * @ping:	The routine that sends a keepalive ping to the watchdog device.
 * @status:	The routine that shows the status of the watchdog device.
 * @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
 * @set_pretimeout:The routine for setting the watchdog devices pretimeout.
 * @get_timeleft:The routine that gets the time left before a reset (in seconds).
 * @restart:	The routine for restarting the machine.
 * @ioctl:	The routines that handles extra ioctl calls.
 *
 * The watchdog_ops structure contains a list of low-level operations
 * that control a watchdog device. It also contains the module that owns
 * these operations. The start function is mandatory, all other
 * functions are optional.
 */
struct watchdog_ops { … };

/** struct watchdog_device - The structure that defines a watchdog device
 *
 * @id:		The watchdog's ID. (Allocated by watchdog_register_device)
 * @parent:	The parent bus device
 * @groups:	List of sysfs attribute groups to create when creating the
 *		watchdog device.
 * @info:	Pointer to a watchdog_info structure.
 * @ops:	Pointer to the list of watchdog operations.
 * @gov:	Pointer to watchdog pretimeout governor.
 * @bootstatus:	Status of the watchdog device at boot.
 * @timeout:	The watchdog devices timeout value (in seconds).
 * @pretimeout: The watchdog devices pre_timeout value.
 * @min_timeout:The watchdog devices minimum timeout value (in seconds).
 * @max_timeout:The watchdog devices maximum timeout value (in seconds)
 *		as configurable from user space. Only relevant if
 *		max_hw_heartbeat_ms is not provided.
 * @min_hw_heartbeat_ms:
 *		Hardware limit for minimum time between heartbeats,
 *		in milli-seconds.
 * @max_hw_heartbeat_ms:
 *		Hardware limit for maximum timeout, in milli-seconds.
 *		Replaces max_timeout if specified.
 * @reboot_nb:	The notifier block to stop watchdog on reboot.
 * @restart_nb:	The notifier block to register a restart function.
 * @driver_data:Pointer to the drivers private data.
 * @wd_data:	Pointer to watchdog core internal data.
 * @status:	Field that contains the devices internal status bits.
 * @deferred:	Entry in wtd_deferred_reg_list which is used to
 *		register early initialized watchdogs.
 *
 * The watchdog_device structure contains all information about a
 * watchdog timer device.
 *
 * The driver-data field may not be accessed directly. It must be accessed
 * via the watchdog_set_drvdata and watchdog_get_drvdata helpers.
 */
struct watchdog_device { … };

#define WATCHDOG_NOWAYOUT …
#define WATCHDOG_NOWAYOUT_INIT_STATUS …

/* Use the following function to check whether or not the watchdog is active */
static inline bool watchdog_active(struct watchdog_device *wdd)
{ … }

/*
 * Use the following function to check whether or not the hardware watchdog
 * is running
 */
static inline bool watchdog_hw_running(struct watchdog_device *wdd)
{ … }

/* Use the following function to set the nowayout feature */
static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
{ … }

/* Use the following function to stop the watchdog on reboot */
static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
{ … }

/* Use the following function to stop the watchdog when unregistering it */
static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
{ … }

/* Use the following function to stop the wdog ping worker when suspending */
static inline void watchdog_stop_ping_on_suspend(struct watchdog_device *wdd)
{ … }

/* Use the following function to check if a timeout value is invalid */
static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
{ … }

/* Use the following function to check if a pretimeout value is invalid */
static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
					       unsigned int t)
{ … }

/* Use the following functions to manipulate watchdog driver specific data */
static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
{ … }

static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
{ … }

/* Use the following functions to report watchdog pretimeout event */
#if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
void watchdog_notify_pretimeout(struct watchdog_device *wdd);
#else
static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
{
	pr_alert("watchdog%d: pretimeout event\n", wdd->id);
}
#endif

/* drivers/watchdog/watchdog_core.c */
void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
extern int watchdog_init_timeout(struct watchdog_device *wdd,
				  unsigned int timeout_parm, struct device *dev);
extern int watchdog_register_device(struct watchdog_device *);
extern void watchdog_unregister_device(struct watchdog_device *);
int watchdog_dev_suspend(struct watchdog_device *wdd);
int watchdog_dev_resume(struct watchdog_device *wdd);

int watchdog_set_last_hw_keepalive(struct watchdog_device *, unsigned int);

/* devres register variant */
int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);

#endif  /* ifndef _LINUX_WATCHDOG_H */