Merge tag 'leds_for_4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds

Pull LED updates from Jacek Anaszewski:
 "New features and improvements:

   - add new optional brightness_hw_changed attribute for the LEDs that
     may have their brightness level changed autonomously (outside of
     kernel control) by hardware / firmware. The attribute supports
     userspace notifications through POLLPRI events

   - add led_brightness_hw_mon tool that demonstrates how to use the
     aforementioned feature

   - add LED_ON enum for LEDs that can be only turned on/off, and don't
     allow setting other brightness levels

   - allow for adjusting heartbeat trigger blink brightness level

  Fixes and cleanups:

   - avoid harmless maybe-uninitialized warning in leds-ktd2692.c

   - add context to the existing example entries in common LED bindings
     to make the documentation more clear"

* tag 'leds_for_4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
  leds: ledtrig-heartbeat: Make top brightness adjustable
  tools/leds: Add led_hw_brightness_mon program
  leds: class: Add new optional brightness_hw_changed attribute
  leds: ktd2692: avoid harmless maybe-uninitialized warning
  leds: add LED_ON brightness as boolean value
  DT: leds: Improve examples by adding some context

4 files changed, 100 insertions, 8 deletions

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index c621cbbb5768..275f467956ee 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -29,6 +29,15 @@ config LEDS_CLASS_FLASH
 	  for the flash related features of a LED device. It can be built
 	  as a module.
 
+config LEDS_BRIGHTNESS_HW_CHANGED
+	bool "LED Class brightness_hw_changed attribute support"
+	depends on LEDS_CLASS
+	help
+	  This option enables support for the brightness_hw_changed attribute
+	  for led sysfs class devices under /sys/class/leds.
+
+	  See Documentation/ABI/testing/sysfs-class-led for details.
+
 comment "LED drivers"
 
 config LEDS_88PM860X
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 326ee6e925a2..f2b0a80a62b4 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -103,6 +103,68 @@ static const struct attribute_group *led_groups[] = {
 	NULL,
 };
 
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+static ssize_t brightness_hw_changed_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+
+	if (led_cdev->brightness_hw_changed == -1)
+		return -ENODATA;
+
+	return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
+}
+
+static DEVICE_ATTR_RO(brightness_hw_changed);
+
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+	struct device *dev = led_cdev->dev;
+	int ret;
+
+	ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
+	if (ret) {
+		dev_err(dev, "Error creating brightness_hw_changed\n");
+		return ret;
+	}
+
+	led_cdev->brightness_hw_changed_kn =
+		sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
+	if (!led_cdev->brightness_hw_changed_kn) {
+		dev_err(dev, "Error getting brightness_hw_changed kn\n");
+		device_remove_file(dev, &dev_attr_brightness_hw_changed);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+	sysfs_put(led_cdev->brightness_hw_changed_kn);
+	device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
+}
+
+void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev,
+					       enum led_brightness brightness)
+{
+	if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
+		return;
+
+	led_cdev->brightness_hw_changed = brightness;
+	sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
+}
+EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
+#else
+static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+	return 0;
+}
+static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
+{
+}
+#endif
+
 /**
  * led_classdev_suspend - suspend an led_classdev.
  * @led_cdev: the led_classdev to suspend.
@@ -204,10 +266,21 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 		dev_warn(parent, "Led %s renamed to %s due to name collision",
 				led_cdev->name, dev_name(led_cdev->dev));
 
+	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
+		ret = led_add_brightness_hw_changed(led_cdev);
+		if (ret) {
+			device_unregister(led_cdev->dev);
+			return ret;
+		}
+	}
+
 	led_cdev->work_flags = 0;
 #ifdef CONFIG_LEDS_TRIGGERS
 	init_rwsem(&led_cdev->trigger_lock);
 #endif
+#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
+	led_cdev->brightness_hw_changed = -1;
+#endif
 	mutex_init(&led_cdev->led_access);
 	/* add to the list of leds */
 	down_write(&leds_list_lock);
@@ -256,6 +329,9 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 
 	flush_work(&led_cdev->set_brightness_work);
 
+	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
+		led_remove_brightness_hw_changed(led_cdev);
+
 	device_unregister(led_cdev->dev);
 
 	down_write(&leds_list_lock);
diff --git a/drivers/leds/leds-ktd2692.c b/drivers/leds/leds-ktd2692.c
index bf23ba191ad0..45296aaca9da 100644
--- a/drivers/leds/leds-ktd2692.c
+++ b/drivers/leds/leds-ktd2692.c
@@ -270,15 +270,15 @@ static int ktd2692_parse_dt(struct ktd2692_context *led, struct device *dev,
 		return -ENXIO;
 
 	led->ctrl_gpio = devm_gpiod_get(dev, "ctrl", GPIOD_ASIS);
-	if (IS_ERR(led->ctrl_gpio)) {
-		ret = PTR_ERR(led->ctrl_gpio);
+	ret = PTR_ERR_OR_ZERO(led->ctrl_gpio);
+	if (ret) {
 		dev_err(dev, "cannot get ctrl-gpios %d\n", ret);
 		return ret;
 	}
 
 	led->aux_gpio = devm_gpiod_get(dev, "aux", GPIOD_ASIS);
-	if (IS_ERR(led->aux_gpio)) {
-		ret = PTR_ERR(led->aux_gpio);
+	ret = PTR_ERR_OR_ZERO(led->aux_gpio);
+	if (ret) {
 		dev_err(dev, "cannot get aux-gpios %d\n", ret);
 		return ret;
 	}
diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
index c9f386213e9e..e6f2f8b9f09a 100644
--- a/drivers/leds/trigger/ledtrig-heartbeat.c
+++ b/drivers/leds/trigger/ledtrig-heartbeat.c
@@ -43,6 +43,9 @@ static void led_heartbeat_function(unsigned long data)
 		return;
 	}
 
+	if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
+		led_cdev->blink_brightness = led_cdev->new_blink_brightness;
+
 	/* acts like an actual heart beat -- ie thump-thump-pause... */
 	switch (heartbeat_data->phase) {
 	case 0:
@@ -59,26 +62,26 @@ static void led_heartbeat_function(unsigned long data)
 		delay = msecs_to_jiffies(70);
 		heartbeat_data->phase++;
 		if (!heartbeat_data->invert)
-			brightness = led_cdev->max_brightness;
+			brightness = led_cdev->blink_brightness;
 		break;
 	case 1:
 		delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
 		heartbeat_data->phase++;
 		if (heartbeat_data->invert)
-			brightness = led_cdev->max_brightness;
+			brightness = led_cdev->blink_brightness;
 		break;
 	case 2:
 		delay = msecs_to_jiffies(70);
 		heartbeat_data->phase++;
 		if (!heartbeat_data->invert)
-			brightness = led_cdev->max_brightness;
+			brightness = led_cdev->blink_brightness;
 		break;
 	default:
 		delay = heartbeat_data->period - heartbeat_data->period / 4 -
 			msecs_to_jiffies(70);
 		heartbeat_data->phase = 0;
 		if (heartbeat_data->invert)
-			brightness = led_cdev->max_brightness;
+			brightness = led_cdev->blink_brightness;
 		break;
 	}
 
@@ -133,7 +136,10 @@ static void heartbeat_trig_activate(struct led_classdev *led_cdev)
 	setup_timer(&heartbeat_data->timer,
 		    led_heartbeat_function, (unsigned long) led_cdev);
 	heartbeat_data->phase = 0;
+	if (!led_cdev->blink_brightness)
+		led_cdev->blink_brightness = led_cdev->max_brightness;
 	led_heartbeat_function(heartbeat_data->timer.data);
+	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 	led_cdev->activated = true;
 }
 
@@ -145,6 +151,7 @@ static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 		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;
 	}
 }