[v4,2/4] leds: Add managed API to get a LED from a device driver

Submitted by Jean-Jacques Hiblot on July 17, 2019, 2:15 p.m.

Details

Message ID 20190717141514.21171-3-jjhiblot@ti.com
State New
Headers show
Series "Add a generic driver for LED-based backlight" ( rev: 4 ) in DRI devel

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Commit Message

Jean-Jacques Hiblot July 17, 2019, 2:15 p.m.
If the LED is acquired by a consumer device with devm_led_get(), it is
automatically released when the device is detached.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
---
 drivers/leds/led-class.c | 42 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  2 ++
 2 files changed, 44 insertions(+)

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diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 9f48798a713d..714b55f1da0f 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -263,6 +263,48 @@  void led_put(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_put);
 
+static void devm_led_release(struct device *dev, void *res)
+{
+	struct led_classdev **p = res;
+
+	led_put(*p);
+}
+
+/**
+ * devm_led_get - Resource-managed request of a LED device
+ * @dev:	LED consumer
+ * @idx:	index of the LED to obtain in the consumer
+ *
+ * The device node of the device is parse to find the request LED device.
+ * The LED device returned from this function is automatically released
+ * on driver detach.
+ *
+ * @return a pointer to a LED device or ERR_PTR(errno) on failure.
+ */
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index)
+{
+	struct led_classdev *led;
+	struct led_classdev **dr;
+
+	led = of_led_get(dev->of_node, index);
+	if (IS_ERR(led))
+		return led;
+
+	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
+			  GFP_KERNEL);
+	if (!dr) {
+		led_put(led);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	*dr = led;
+	devres_add(dev, dr);
+
+	return led;
+}
+EXPORT_SYMBOL_GPL(devm_led_get);
+
 static int match_name(struct device *dev, const void *data)
 {
 	if (!dev_name(dev))
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 0a71c7cdd191..7fcec566d774 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -148,6 +148,8 @@  extern void led_classdev_resume(struct led_classdev *led_cdev);
 
 extern struct led_classdev *of_led_get(struct device_node *np, int index);
 extern void led_put(struct led_classdev *led_cdev);
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index);
 
 /**
  * led_blink_set - set blinking with software fallback

Comments

On 17/07/2019 17:15, Jean-Jacques Hiblot wrote:

> +struct led_classdev *__must_check devm_led_get(struct device *dev,
> +					       int index)
> +{
> +	struct led_classdev *led;
> +	struct led_classdev **dr;
> +

Should you check here if dev->of_node == NULL? Or should of_led_get() 
check it.

> +	led = of_led_get(dev->of_node, index);
> +	if (IS_ERR(led))
> +		return led;
> +
> +	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
> +			  GFP_KERNEL);
> +	if (!dr) {
> +		led_put(led);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	*dr = led;
> +	devres_add(dev, dr);
> +
> +	return led;
> +}

  Tomi