watchdog: Make stop function optional
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@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
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@ -85,7 +85,8 @@ It contains following fields:
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If set, the infrastructure will send heartbeats to the watchdog driver
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If set, the infrastructure will send heartbeats to the watchdog driver
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if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE
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if 'timeout' is larger than max_hw_heartbeat_ms, unless WDOG_ACTIVE
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is set and userspace failed to send a heartbeat for at least 'timeout'
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is set and userspace failed to send a heartbeat for at least 'timeout'
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seconds.
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seconds. max_hw_heartbeat_ms must be set if a driver does not implement
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the stop function.
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* reboot_nb: notifier block that is registered for reboot notifications, for
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* reboot_nb: notifier block that is registered for reboot notifications, for
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internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
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internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
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will stop the watchdog on such notifications.
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will stop the watchdog on such notifications.
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@ -134,17 +135,20 @@ are:
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device.
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device.
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The routine needs a pointer to the watchdog timer device structure as a
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The routine needs a pointer to the watchdog timer device structure as a
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parameter. It returns zero on success or a negative errno code for failure.
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parameter. It returns zero on success or a negative errno code for failure.
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* stop: with this routine the watchdog timer device is being stopped.
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The routine needs a pointer to the watchdog timer device structure as a
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parameter. It returns zero on success or a negative errno code for failure.
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Some watchdog timer hardware can only be started and not be stopped.
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If a watchdog can not be stopped, the watchdog driver must set the
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WDOG_HW_RUNNING flag in its stop function to inform the watchdog core that
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the watchdog is still running.
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Not all watchdog timer hardware supports the same functionality. That's why
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Not all watchdog timer hardware supports the same functionality. That's why
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all other routines/operations are optional. They only need to be provided if
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all other routines/operations are optional. They only need to be provided if
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they are supported. These optional routines/operations are:
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they are supported. These optional routines/operations are:
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* stop: with this routine the watchdog timer device is being stopped.
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The routine needs a pointer to the watchdog timer device structure as a
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parameter. It returns zero on success or a negative errno code for failure.
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Some watchdog timer hardware can only be started and not be stopped. A
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driver supporting such hardware does not have to implement the stop routine.
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If a driver has no stop function, the watchdog core will set WDOG_HW_RUNNING
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and start calling the driver's keepalive pings function after the watchdog
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device is closed.
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If a watchdog driver does not implement the stop function, it must set
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max_hw_heartbeat_ms.
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* ping: this is the routine that sends a keepalive ping to the watchdog timer
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* ping: this is the routine that sends a keepalive ping to the watchdog timer
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hardware.
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hardware.
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The routine needs a pointer to the watchdog timer device structure as a
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The routine needs a pointer to the watchdog timer device structure as a
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@ -199,7 +199,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
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return -EINVAL;
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return -EINVAL;
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/* Mandatory operations need to be supported */
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/* Mandatory operations need to be supported */
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if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
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if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
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return -EINVAL;
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return -EINVAL;
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watchdog_check_min_max_timeout(wdd);
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watchdog_check_min_max_timeout(wdd);
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@ -246,7 +246,11 @@ static int watchdog_stop(struct watchdog_device *wdd)
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return -EBUSY;
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return -EBUSY;
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}
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}
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err = wdd->ops->stop(wdd);
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if (wdd->ops->stop)
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err = wdd->ops->stop(wdd);
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else
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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if (err == 0) {
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if (err == 0) {
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clear_bit(WDOG_ACTIVE, &wdd->status);
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clear_bit(WDOG_ACTIVE, &wdd->status);
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watchdog_update_worker(wdd);
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watchdog_update_worker(wdd);
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