watchdog: ziirave_wdt: Be verbose about errors in probe()

The driver is quite silent in case of probe failure, which makes it
more difficult to diagnose problem from the kernel log. Add logging to
all of the silent error paths ziirave_wdt_probe() to improve that.

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/20190812200906.31344-3-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

@@ -658,8 +658,10 @@ static int ziirave_wdt_probe(struct i2c_client *client,
 	 */
 	if (w_priv->wdd.timeout == 0) {
 		val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);
-		if (val < 0)
+		if (val < 0) {
+			dev_err(&client->dev, "Failed to read timeout\n");
 			return val;
+		}
 
 		if (val < ZIIRAVE_TIMEOUT_MIN)
 			return -ENODEV;
@@ -668,8 +670,10 @@ static int ziirave_wdt_probe(struct i2c_client *client,
 	} else {
 		ret = ziirave_wdt_set_timeout(&w_priv->wdd,
 					      w_priv->wdd.timeout);
-		if (ret)
+		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);
@@ -681,34 +685,46 @@ static int ziirave_wdt_probe(struct i2c_client *client,
 
 	/* If in unconfigured state, set to stopped */
 	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);
-	if (val < 0)
+	if (val < 0) {
+		dev_err(&client->dev, "Failed to read state\n");
 		return val;
+	}
 
 	if (val == ZIIRAVE_STATE_INITIAL)
 		ziirave_wdt_stop(&w_priv->wdd);
 
 	ret = ziirave_wdt_init_duration(client);
-	if (ret)
+	if (ret) {
+		dev_err(&client->dev, "Failed to init duration\n");
 		return ret;
+	}
 
 	ret = ziirave_wdt_revision(client, &w_priv->firmware_rev,
 				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
-	if (ret)
+	if (ret) {
+		dev_err(&client->dev, "Failed to read firmware version\n");
 		return ret;
+	}
 
 	ret = ziirave_wdt_revision(client, &w_priv->bootloader_rev,
 				   ZIIRAVE_WDT_BOOT_VER_MAJOR);
-	if (ret)
+	if (ret) {
+		dev_err(&client->dev, "Failed to read bootloader version\n");
 		return ret;
+	}
 
 	w_priv->reset_reason = i2c_smbus_read_byte_data(client,
 						ZIIRAVE_WDT_RESET_REASON);
-	if (w_priv->reset_reason < 0)
+	if (w_priv->reset_reason < 0) {
+		dev_err(&client->dev, "Failed to read reset reason\n");
 		return w_priv->reset_reason;
+	}
 
 	if (w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons) ||
-	    !ziirave_reasons[w_priv->reset_reason])
+	    !ziirave_reasons[w_priv->reset_reason]) {
+		dev_err(&client->dev, "Invalid reset reason\n");
 		return -ENODEV;
+	}
 
 	ret = watchdog_register_device(&w_priv->wdd);