Some watchdogs require a minimum time between heartbeats.
Examples are the watchdogs in DA9062 and AT91SAM9x.
Signed-off-by: Guenter Roeck <li...@roeck-us.net>
---
v6: Rebased to v4.4-rc2
v5: Rebased to v4.4-rc1
Fixed typo in documentation.
v4: Added patch
---
Documentation/watchdog/watchdog-kernel-api.txt | 4 ++++
drivers/watchdog/watchdog_dev.c | 12 ++++++++++++
include/linux/watchdog.h | 6 ++++++
3 files changed, 22 insertions(+)
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt
b/Documentation/watchdog/watchdog-kernel-api.txt
index f2ee8226d320..b417fdb6caac 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,11 +53,13 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int min_hw_heartbeat_ms;
unsigned int max_hw_timeout_ms;
void *driver_data;
unsigned long status;
struct mutex lock;
unsigned long last_keepalive;
+ unsigned long last_hw_keepalive;
struct delayed_work work;
struct list_head deferred;
};
@@ -83,6 +85,8 @@ 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_timeout_ms is non-zero.
+* min_hw_heartbeat_ms: Minimum time between heartbeats sent to the chip,
+ in milli-seconds.
* max_hw_timeout_ms: Maximum hardware timeout, in milli-seconds.
If set, the infrastructure will send heartbeats to the watchdog driver
if 'timeout' is larger than max_hw_timeout, unless WDOG_ACTIVE
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 5dd7319c0169..82706d43e0c8 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -111,6 +111,8 @@ static inline void watchdog_update_worker(struct
watchdog_device *wdd,
static int _watchdog_ping(struct watchdog_device *wdd)
{
+ unsigned long earliest_keepalive = wdd->last_hw_keepalive +
+ msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
int err;
if (test_bit(WDOG_UNREGISTERED, &wdd->status))
@@ -119,6 +121,13 @@ static int _watchdog_ping(struct watchdog_device *wdd)
if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
return 0;
+ if (time_is_after_jiffies(earliest_keepalive)) {
+ mod_delayed_work(watchdog_wq, &wdd->work,
+ earliest_keepalive - jiffies);
+ return 0;
+ }
+
+ wdd->last_hw_keepalive = jiffies;
if (wdd->ops->ping)
err = wdd->ops->ping(wdd); /* ping the watchdog */
else
@@ -667,6 +676,9 @@ int watchdog_dev_register(struct watchdog_device *wdd)
return err;
}
+ /* Record time of most recent heartbeat as 'just before now'. */
+ wdd->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 98f79db93600..606dfd55927f 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -66,6 +66,8 @@ struct watchdog_ops {
* @max_timeout:The watchdog devices maximum timeout value (in seconds)
* as configurable from user space. Only relevant if
* max_hw_timeout_ms is not provided.
+ * @min_hw_heartbeat_ms:
+ * Minimum time between heartbeats, in milli-seconds.
* @max_hw_timeout_ms:
* Hardware limit for maximum timeout, in milli-seconds.
* Replaces max_timeout if specified.
@@ -75,6 +77,8 @@ struct watchdog_ops {
* @last_keepalive:
* Time of most recent keepalive triggered from user space,
* in jiffies (watchdog core internal).
+ * @last_hw_keepalive:
+ * Time of most recent keepalive sent to the driver, in jiffies.
* @work: Data structure for worker function (watchdog core internal).
* @deferred: entry in wtd_deferred_reg_list which is used to
* register early initialized watchdogs.
@@ -99,6 +103,7 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int min_hw_heartbeat_ms;
unsigned int max_hw_timeout_ms;
void *driver_data;
unsigned long status;
@@ -112,6 +117,7 @@ struct watchdog_device {
/* the following variables are for internal use only */
struct mutex lock;
unsigned long last_keepalive;
+ unsigned long last_hw_keepalive;
struct delayed_work work;
struct list_head deferred;
};
--
2.1.4
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