leds: heartbeat trigger: simplifications from core changes

The trigger core learned error handling for the activate callback and
can handle device attributes now. This allows simplifying the driver
considerably. Note that .deactivate() is only called when .activate()
succeeded, so the check for .activated can go away in .deactivate().

Also make use of module_led_trigger() and the accessor function to get
and set trigger_data.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

drivers/leds/trigger/ledtrig-heartbeat.c

@@ -96,8 +96,8 @@ static void led_heartbeat_function(struct timer_list *t)
 static ssize_t led_invert_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
-	struct led_classdev *led_cdev = dev_get_drvdata(dev);
-	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
+	struct heartbeat_trig_data *heartbeat_data =
+		led_trigger_get_drvdata(dev);
 
 	return sprintf(buf, "%u\n", heartbeat_data->invert);
 }
@@ -105,8 +105,8 @@ static ssize_t led_invert_show(struct device *dev,
 static ssize_t led_invert_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t size)
 {
-	struct led_classdev *led_cdev = dev_get_drvdata(dev);
-	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
+	struct heartbeat_trig_data *heartbeat_data =
+		led_trigger_get_drvdata(dev);
 	unsigned long state;
 	int ret;
 
@@ -121,22 +121,22 @@ static ssize_t led_invert_store(struct device *dev,
 
 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
 
+static struct attribute *heartbeat_trig_attrs[] = {
+	&dev_attr_invert.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(heartbeat_trig);
+
 static int heartbeat_trig_activate(struct led_classdev *led_cdev)
 {
 	struct heartbeat_trig_data *heartbeat_data;
-	int rc;
 
 	heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 	if (!heartbeat_data)
-		return 0;
+		return -ENOMEM;
 
-	led_cdev->trigger_data = heartbeat_data;
+	led_set_trigger_data(led_cdev, heartbeat_data);
 	heartbeat_data->led_cdev = led_cdev;
-	rc = device_create_file(led_cdev->dev, &dev_attr_invert);
-	if (rc) {
-		kfree(led_cdev->trigger_data);
-		return 0;
-	}
 
 	timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
 	heartbeat_data->phase = 0;
@@ -144,28 +144,25 @@ static int heartbeat_trig_activate(struct led_classdev *led_cdev)
 		led_cdev->blink_brightness = led_cdev->max_brightness;
 	led_heartbeat_function(&heartbeat_data->timer);
 	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
-	led_cdev->activated = true;
 
 	return 0;
 }
 
 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 {
-	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
-
-	if (led_cdev->activated) {
-		del_timer_sync(&heartbeat_data->timer);
-		device_remove_file(led_cdev->dev, &dev_attr_invert);
-		kfree(heartbeat_data);
-		clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
-		led_cdev->activated = false;
-	}
+	struct heartbeat_trig_data *heartbeat_data =
+		led_get_trigger_data(led_cdev);
+
+	del_timer_sync(&heartbeat_data->timer);
+	kfree(heartbeat_data);
+	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 }
 
 static struct led_trigger heartbeat_led_trigger = {
 	.name     = "heartbeat",
 	.activate = heartbeat_trig_activate,
 	.deactivate = heartbeat_trig_deactivate,
+	.groups = heartbeat_trig_groups,
 };
 
 static int heartbeat_reboot_notifier(struct notifier_block *nb,