Not all hardware watchdogs can be stopped. The driver for
such watchdogs would typically only set the WATCHDOG_HW_RUNNING
flag in its stop function. Make the stop function optional and set
WATCHDOG_HW_RUNNING in the watchdog core if it is not provided.
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
v8: Split functionality from patch introducing WATCHDOG_HW_RUNNING
---
Documentation/watchdog/watchdog-kernel-api.txt | 20 ++++++++++++--------
drivers/watchdog/watchdog_core.c | 2 +-
drivers/watchdog/watchdog_dev.c | 6 +++++-
3 files changed, 18 insertions(+), 10 deletions(-)
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 954134a5c4a4..9eabca1d9355 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -85,7 +85,8 @@ It contains following fields:
If set, the infrastructure will send heartbeats to the watchdog driver
if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE
is set and userspace failed to send a heartbeat for at least 'timeout'
- seconds.
+ seconds. max_hw_heartbeat_ms must be set if a driver does not implement
+ the stop function.
* reboot_nb: notifier block that is registered for reboot notifications, for
internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
will stop the watchdog on such notifications.
@@ -134,17 +135,20 @@ are:
device.
The routine needs a pointer to the watchdog timer device structure as a
parameter. It returns zero on success or a negative errno code for failure.
-* stop: with this routine the watchdog timer device is being stopped.
- The routine needs a pointer to the watchdog timer device structure as a
- parameter. It returns zero on success or a negative errno code for failure.
- Some watchdog timer hardware can only be started and not be stopped.
- If a watchdog can not be stopped, the watchdog driver must set the
- WDOG_HW_RUNNING flag in its stop function to inform the watchdog core that
- the watchdog is still running.
Not all watchdog timer hardware supports the same functionality. That's why
all other routines/operations are optional. They only need to be provided if
they are supported. These optional routines/operations are:
+* stop: with this routine the watchdog timer device is being stopped.
+ The routine needs a pointer to the watchdog timer device structure as a
+ parameter. It returns zero on success or a negative errno code for failure.
+ Some watchdog timer hardware can only be started and not be stopped. A
+ driver supporting such hardware does not have to implement the stop routine.
+ If a driver has no stop function, the watchdog core will set WDOG_HW_RUNNING
+ and start calling the driver's keepalive pings function after the watchdog
+ device is closed.
+ If a watchdog driver does not implement the stop function, it must set
+ max_hw_heartbeat_ms.
* ping: this is the routine that sends a keepalive ping to the watchdog timer
hardware.
The routine needs a pointer to the watchdog timer device structure as a
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index e600fd93b7de..45aabbd52b02 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -199,7 +199,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
return -EINVAL;
/* Mandatory operations need to be supported */
- if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
+ if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
return -EINVAL;
watchdog_check_min_max_timeout(wdd);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 5d3a9fa4856e..5163c3eb3428 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -246,7 +246,11 @@ static int watchdog_stop(struct watchdog_device *wdd)
return -EBUSY;
}
- err = wdd->ops->stop(wdd);
+ if (wdd->ops->stop)
+ err = wdd->ops->stop(wdd);
+ else
+ set_bit(WDOG_HW_RUNNING, &wdd->status);
+
if (err == 0) {
clear_bit(WDOG_ACTIVE, &wdd->status);
watchdog_update_worker(wdd);
--
2.5.0
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