[PATCH v5 3/8] watchdog: Make set_timeout function optional

[Guenter Roeck <linux@roeck-us.net>]

For some watchdogs, the hardware timeout is fixed, and the
watchdog driver depends on the watchdog core to handle the
actual timeout. In this situation, the watchdog driver might
only set the 'timeout' variable but do nothing else.
This can as well be handled by the infrastructure, so make
the set_timeout callback optional. If WDIOF_SETTIMEOUT is
configured but the .set_timeout callback is not available,
update the timeout variable in the infrastructure code.

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v5: Rebased to v4.4-rc1
v4: No changes
v3: No changes
v2: No changes
---
 Documentation/watchdog/watchdog-kernel-api.txt | 5 +++++
 drivers/watchdog/watchdog_dev.c                | 9 ++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index 3f0963b2c33e..f480a9355b43 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -184,6 +184,11 @@ they are supported. These optional routines/operations are:
   (if it is larger than hw_max_timeout_ms), or to the achieved timeout value.
   (Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
   watchdog's info structure).
+  If the watchdog driver does not have to perform any action but setting the
+  watchdog_device.timeout, this callback can be omitted.
+  If set_timeout is not provided but, WDIOF_SETTIMEOUT is set, the watchdog
+  infrastructure updates the timeout value of the watchdog_device internally
+  to the requested value.
 * get_timeleft: this routines returns the time that's left before a reset.
 * ref: the operation that calls kref_get on the kref of a dynamically
   allocated watchdog_device struct.
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index bb3bd16ffaf6..e73407b42df5 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -282,9 +282,9 @@ out_status:
 static int watchdog_set_timeout(struct watchdog_device *wdd,
 							unsigned int timeout)
 {
-	int err;
+	int err = 0;
 
-	if (!wdd->ops->set_timeout || !(wdd->info->options & WDIOF_SETTIMEOUT))
+	if (!(wdd->info->options & WDIOF_SETTIMEOUT))
 		return -EOPNOTSUPP;
 
 	if (watchdog_timeout_invalid(wdd, timeout))
@@ -297,7 +297,10 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
 		goto out_timeout;
 	}
 
-	err = wdd->ops->set_timeout(wdd, timeout);
+	if (wdd->ops->set_timeout)
+		err = wdd->ops->set_timeout(wdd, timeout);
+	else
+		wdd->timeout = timeout;
 
 	watchdog_update_worker(wdd, true);
 
-- 
2.1.4