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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: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Guenter Roeck 2016-02-28 13:12:18 -08:00 committed by Wim Van Sebroeck
parent d0684c8a93
commit 15013ad813
3 changed files with 21 additions and 0 deletions
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3
Documentation/watchdog/watchdog-kernel-api.txt
View File

@ -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

15
drivers/watchdog/watchdog_dev.c
View File

@ -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.

3
include/linux/watchdog.h
View File

@ -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;