watchdog: ziirave_wdt: Don't bail out on unexpected timeout value

Reprogramming bootloader on watchdog MCU will result in reported
default timeout value of "0". That in turn will be unnecessarily
rejected by the driver as invalid device (-ENODEV). Simplify probe to
read stored timeout value, set it to a sane default if it is bogus,
and then program that value unconditionally.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Rick Ramstetter <rick@anteaterllc.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190812200906.31344-5-andrew.smirnov@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/ziirave_wdt.c

@@ -23,6 +23,7 @@
 
 #define ZIIRAVE_TIMEOUT_MIN	3
 #define ZIIRAVE_TIMEOUT_MAX	255
+#define ZIIRAVE_TIMEOUT_DEFAULT	30
 
 #define ZIIRAVE_PING_VALUE	0x0
 
@@ -673,22 +674,21 @@ static int ziirave_wdt_probe(struct i2c_client *client,
 			return val;
 		}
 
-		if (val < ZIIRAVE_TIMEOUT_MIN)
-			return -ENODEV;
+		if (val > ZIIRAVE_TIMEOUT_MAX ||
+		    val < ZIIRAVE_TIMEOUT_MIN)
+			val = ZIIRAVE_TIMEOUT_DEFAULT;
 
 		w_priv->wdd.timeout = val;
-	} else {
-		ret = ziirave_wdt_set_timeout(&w_priv->wdd,
-					      w_priv->wdd.timeout);
-		if (ret) {
-			dev_err(&client->dev, "Failed to set timeout\n");
-			return ret;
-		}
+	}
 
-		dev_info(&client->dev, "Timeout set to %ds\n",
-			 w_priv->wdd.timeout);
+	ret = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
+	if (ret) {
+		dev_err(&client->dev, "Failed to set timeout\n");
+		return ret;
 	}
 
+	dev_info(&client->dev, "Timeout set to %ds\n", w_priv->wdd.timeout);
+
 	watchdog_set_nowayout(&w_priv->wdd, nowayout);
 
 	i2c_set_clientdata(client, w_priv);