[PATCH 01/16] watchdog: refactor watchdog_init_timeout

[Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>]

The function is not easy to read and has two problems: a) -EINVAL is
returned when the module parameter is invalid but the DT parameter is
OK, and b) for the module parameter, zero is a valid value but for DT it
is invalid.

Refactor the code to have a the same pattern of checks for the module
parameter and DT. Further ones can be easily added in the future if the
need arises. The above mentioned problems are fixed, too.

Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
 drivers/watchdog/watchdog_core.c | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index eb8fa25f8eb2..85c136acc0e9 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -104,10 +104,11 @@ static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
  * Initialize the timeout field of the watchdog_device struct with either the
  * timeout module parameter (if it is valid value) or the timeout-sec property
  * (only if it is a valid value and the timeout_parm is out of bounds).
- * If none of them are valid then we keep the old value (which should normally
- * be the default timeout value).
+ * If none of them are valid or all of them are zero ("don't care") then we keep
+ * the old value (which should normally be the default timeout value).
  *
- * A zero is returned on success and -EINVAL for failure.
+ * A zero is returned on success or -EINVAL if all provided values are out of
+ * bounds.
  */
 int watchdog_init_timeout(struct watchdog_device *wdd,
 				unsigned int timeout_parm, struct device *dev)
@@ -117,22 +118,24 @@ int watchdog_init_timeout(struct watchdog_device *wdd,
 
 	watchdog_check_min_max_timeout(wdd);
 
-	/* try to get the timeout module parameter first */
-	if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
-		wdd->timeout = timeout_parm;
-		return ret;
-	}
-	if (timeout_parm)
+	/* check the driver supplied value (likely a module parameter) first */
+	if (timeout_parm) {
+		if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
+			wdd->timeout = timeout_parm;
+			return 0;
+		}
 		ret = -EINVAL;
+	}
 
 	/* try to get the timeout_sec property */
-	if (dev == NULL || dev->of_node == NULL)
-		return ret;
-	of_property_read_u32(dev->of_node, "timeout-sec", &t);
-	if (!watchdog_timeout_invalid(wdd, t) && t)
-		wdd->timeout = t;
-	else
+	if (dev && dev->of_node &&
+	    of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0 && t) {
+		if (!watchdog_timeout_invalid(wdd, t)) {
+			wdd->timeout = t;
+			return 0;
+		}
 		ret = -EINVAL;
+	}
 
 	return ret;
 }
-- 
2.11.0