counter: 104-quad-8: Return error when invalid mode during ceiling_write

[ Upstream commit 728246e ]

The 104-QUAD-8 only has two count modes where a ceiling value makes
sense: Range Limit and Modulo-N. Outside of these two modes, setting a
ceiling value is an invalid operation -- so let's report it as such by
returning -EINVAL.

Fixes: fc06926 ("counter: 104-quad-8: Add lock guards - generic interface")
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/a2147f022829b66839a1db5530a7fada47856847.1627990337.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/counter/104-quad-8.c

@@ -1224,12 +1224,13 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
 	case 1:
 	case 3:
 		quad8_preset_register_set(priv, count->id, ceiling);
-		break;
+		mutex_unlock(&priv->lock);
+		return len;
 	}
 
 	mutex_unlock(&priv->lock);
 
-	return len;
+	return -EINVAL;
 }
 
 static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,