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Commit 15013ad8 authored by Guenter Roeck's avatar Guenter Roeck Committed by Wim Van Sebroeck
Browse files

watchdog: Add support for minimum time between heartbeats 



Some watchdogs require a minimum time between heartbeats.
Examples are the watchdogs in DA9062 and AT91SAM9x.

Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
parent d0684c8a

Documentation/watchdog/watchdog-kernel-api.txt

+3 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct watchdog_device { 
	unsigned int timeout;

	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;
@@ -81,6 +82,8 @@ It contains following fields: 
* max_timeout: the watchdog timer's maximum timeout value (in seconds),

  as seen from userspace. If set, the maximum configurable value for

  'timeout'. Not used if max_hw_heartbeat_ms is non-zero.

* min_hw_heartbeat_ms: Minimum time between heartbeats sent to the chip,

  in milli-seconds.

* max_hw_heartbeat_ms: Maximum hardware heartbeat, in milli-seconds.

  If set, the infrastructure will send heartbeats to the watchdog driver

  if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE

drivers/watchdog/watchdog_dev.c

+15 −0
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ struct watchdog_core_data { 
	struct watchdog_device *wdd;

	struct mutex lock;

	unsigned long last_keepalive;

	unsigned long last_hw_keepalive;

	struct delayed_work work;

	unsigned long status;		/* Internal status bits */

#define _WDOG_DEV_OPEN		0	/* Opened ? */
@@ -137,8 +138,19 @@ static inline void watchdog_update_worker(struct watchdog_device *wdd) 


static int __watchdog_ping(struct watchdog_device *wdd)

{

	struct watchdog_core_data *wd_data = wdd->wd_data;

	unsigned long earliest_keepalive = wd_data->last_hw_keepalive +

				msecs_to_jiffies(wdd->min_hw_heartbeat_ms);

	int err;



	if (time_is_after_jiffies(earliest_keepalive)) {

		mod_delayed_work(watchdog_wq, &wd_data->work,

				 earliest_keepalive - jiffies);

		return 0;

	}



	wd_data->last_hw_keepalive = jiffies;



	if (wdd->ops->ping)

		err = wdd->ops->ping(wdd);  /* ping the watchdog */

	else
@@ -819,6 +831,9 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno) 
		return err;

	}



	/* Record time of most recent heartbeat as 'just before now'. */

	wd_data->last_hw_keepalive = jiffies - 1;



	/*

	 * If the watchdog is running, prevent its driver from being unloaded,

	 * and schedule an immediate ping.

include/linux/watchdog.h

+3 −0
Original line number Diff line number Diff line
@@ -65,6 +65,8 @@ struct watchdog_ops { 
 * @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:

 *		Minimum time between heartbeats, in milli-seconds.

 * @max_hw_heartbeat_ms:

 *		Hardware limit for maximum timeout, in milli-seconds.

 *		Replaces max_timeout if specified.
@@ -95,6 +97,7 @@ struct watchdog_device { 
	unsigned int timeout;

	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;