drivers/video/backlight/led_bl.c

Source file repositories/reference/linux-study-clean/drivers/video/backlight/led_bl.c

File Facts

System
Linux kernel
Corpus path
drivers/video/backlight/led_bl.c
Extension
.c
Size
6460 bytes
Lines
274
Domain
Driver Families
Bucket
drivers/video
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct led_bl_data {
	struct device		*dev;
	struct backlight_device	*bl_dev;
	struct led_classdev	**leds;
	bool			enabled;
	int			nb_leds;
	unsigned int		*levels;
	unsigned int		default_brightness;
	unsigned int		max_brightness;
};

static void led_bl_set_brightness(struct led_bl_data *priv, int level)
{
	int i;
	int bkl_brightness;

	if (priv->levels)
		bkl_brightness = priv->levels[level];
	else
		bkl_brightness = level;

	for (i = 0; i < priv->nb_leds; i++)
		led_set_brightness(priv->leds[i], bkl_brightness);

	priv->enabled = true;
}

static void led_bl_power_off(struct led_bl_data *priv)
{
	int i;

	if (!priv->enabled)
		return;

	for (i = 0; i < priv->nb_leds; i++)
		led_set_brightness(priv->leds[i], LED_OFF);

	priv->enabled = false;
}

static int led_bl_update_status(struct backlight_device *bl)
{
	struct led_bl_data *priv = bl_get_data(bl);
	int brightness = backlight_get_brightness(bl);

	if (brightness > 0)
		led_bl_set_brightness(priv, brightness);
	else
		led_bl_power_off(priv);

	return 0;
}

static const struct backlight_ops led_bl_ops = {
	.update_status	= led_bl_update_status,
};

static int led_bl_get_leds(struct device *dev,
			   struct led_bl_data *priv)
{
	int i, nb_leds, ret;
	struct device_node *node = dev->of_node;
	struct led_classdev **leds;
	unsigned int max_brightness;
	unsigned int default_brightness;

	ret = of_count_phandle_with_args(node, "leds", NULL);
	if (ret < 0) {
		dev_err(dev, "Unable to get led count\n");
		return -EINVAL;
	}

	nb_leds = ret;
	if (nb_leds < 1) {
		dev_err(dev, "At least one LED must be specified!\n");
		return -EINVAL;
	}

	leds = devm_kcalloc(dev, nb_leds, sizeof(struct led_classdev *),
			    GFP_KERNEL);
	if (!leds)
		return -ENOMEM;

	for (i = 0; i < nb_leds; i++) {
		leds[i] = devm_of_led_get(dev, i);
		if (IS_ERR(leds[i]))
			return PTR_ERR(leds[i]);
	}

	/* check that the LEDs all have the same brightness range */

Annotation

Implementation Notes