blob: 1464ce6ffa31b232d6f27e291e3754d0b61dda4f [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
* Generic watchdog defines. Derived from..
* Berkshire PC Watchdog Defines
* by Ken Hollis <>
#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 module *owner;
/* mandatory operations */
int (*start)(struct watchdog_device *);
/* optional operations */
int (*stop)(struct watchdog_device *);
int (*ping)(struct watchdog_device *);
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
int (*set_pretimeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
int (*restart)(struct watchdog_device *, unsigned long, void *);
long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
/** 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 {
int id;
struct device *parent;
const struct attribute_group **groups;
const struct watchdog_info *info;
const struct watchdog_ops *ops;
const struct watchdog_governor *gov;
unsigned int bootstatus;
unsigned int timeout;
unsigned int pretimeout;
unsigned int min_timeout;
unsigned int max_timeout;
unsigned int min_hw_heartbeat_ms;
unsigned int max_hw_heartbeat_ms;
struct notifier_block reboot_nb;
struct notifier_block restart_nb;
void *driver_data;
struct watchdog_core_data *wd_data;
unsigned long status;
/* Bit numbers for status flags */
#define WDOG_ACTIVE 0 /* Is the watchdog running/active */
#define WDOG_NO_WAY_OUT 1 /* Is 'nowayout' feature set ? */
#define WDOG_STOP_ON_REBOOT 2 /* Should be stopped on reboot */
#define WDOG_HW_RUNNING 3 /* True if HW watchdog running */
#define WDOG_STOP_ON_UNREGISTER 4 /* Should be stopped on unregister */
struct list_head deferred;
/* Use the following function to check whether or not the watchdog is active */
static inline bool watchdog_active(struct watchdog_device *wdd)
return test_bit(WDOG_ACTIVE, &wdd->status);
* Use the following function to check whether or not the hardware watchdog
* is running
static inline bool watchdog_hw_running(struct watchdog_device *wdd)
return test_bit(WDOG_HW_RUNNING, &wdd->status);
/* Use the following function to set the nowayout feature */
static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
if (nowayout)
set_bit(WDOG_NO_WAY_OUT, &wdd->status);
/* Use the following function to stop the watchdog on reboot */
static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
/* Use the following function to stop the watchdog when unregistering it */
static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
set_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status);
/* 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)
* The timeout is invalid if
* - the requested value is larger than UINT_MAX / 1000
* (since internal calculations are done in milli-seconds),
* or
* - the requested value is smaller than the configured minimum timeout,
* or
* - a maximum hardware timeout is not configured, a maximum timeout
* is configured, and the requested value is larger than the
* configured maximum timeout.
return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
(!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
t > wdd->max_timeout);
/* 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)
return t && wdd->timeout && t >= wdd->timeout;
/* Use the following functions to manipulate watchdog driver specific data */
static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
wdd->driver_data = data;
static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
return wdd->driver_data;
/* Use the following functions to report watchdog pretimeout event */
void watchdog_notify_pretimeout(struct watchdog_device *wdd);
static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
pr_alert("watchdog%d: pretimeout event\n", wdd->id);
/* 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 *);
/* devres register variant */
int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);
#endif /* ifndef _LINUX_WATCHDOG_H */