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>
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 9eabca1..917eeea 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -52,6 +52,7 @@
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 @@
* 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
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 5163c3e..2d61102 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -64,6 +64,7 @@
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 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 @@
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.
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index e2f4554..51732d6 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -65,6 +65,8 @@
* @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 @@
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;