drivers/leds/trigger/ledtrig-gpio.c

Source file repositories/reference/linux-study-clean/drivers/leds/trigger/ledtrig-gpio.c

File Facts

System
Linux kernel
Corpus path
drivers/leds/trigger/ledtrig-gpio.c
Extension
.c
Size
3615 bytes
Lines
143
Domain
Driver Families
Bucket
drivers/leds
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 gpio_trig_data {
	struct led_classdev *led;
	unsigned desired_brightness;	/* desired brightness when led is on */
	struct gpio_desc *gpiod;	/* gpio that triggers the led */
};

static irqreturn_t gpio_trig_irq(int irq, void *_led)
{
	struct led_classdev *led = _led;
	struct gpio_trig_data *gpio_data = led_get_trigger_data(led);
	int tmp;

	tmp = gpiod_get_value_cansleep(gpio_data->gpiod);
	if (tmp) {
		if (gpio_data->desired_brightness)
			led_set_brightness_nosleep(gpio_data->led,
					   gpio_data->desired_brightness);
		else
			led_set_brightness_nosleep(gpio_data->led, LED_FULL);
	} else {
		led_set_brightness_nosleep(gpio_data->led, LED_OFF);
	}

	return IRQ_HANDLED;
}

static ssize_t desired_brightness_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);

	return sysfs_emit(buf, "%u\n", gpio_data->desired_brightness);
}

static ssize_t desired_brightness_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t n)
{
	struct gpio_trig_data *gpio_data = led_trigger_get_drvdata(dev);
	u8 desired_brightness;
	int ret;

	ret = kstrtou8(buf, 10, &desired_brightness);
	if (ret)
		return ret;

	gpio_data->desired_brightness = desired_brightness;

	return n;
}
static DEVICE_ATTR_RW(desired_brightness);

static struct attribute *gpio_trig_attrs[] = {
	&dev_attr_desired_brightness.attr,
	NULL
};
ATTRIBUTE_GROUPS(gpio_trig);

static int gpio_trig_activate(struct led_classdev *led)
{
	struct gpio_trig_data *gpio_data;
	struct device *dev = led->dev;
	int ret;

	gpio_data = kzalloc_obj(*gpio_data);
	if (!gpio_data)
		return -ENOMEM;

	/*
	 * The generic property "trigger-sources" is followed,
	 * and we hope that this is a GPIO.
	 */
	gpio_data->gpiod = gpiod_get_optional(dev, "trigger-sources",
					      GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
	if (IS_ERR(gpio_data->gpiod)) {
		ret = PTR_ERR(gpio_data->gpiod);
		kfree(gpio_data);
		return ret;
	}
	if (!gpio_data->gpiod) {
		dev_err(dev, "no valid GPIO for the trigger\n");
		kfree(gpio_data);
		return -EINVAL;
	}

	gpiod_set_consumer_name(gpio_data->gpiod, "led-trigger");

	gpio_data->led = led;
	led_set_trigger_data(led, gpio_data);

	ret = request_threaded_irq(gpiod_to_irq(gpio_data->gpiod), NULL, gpio_trig_irq,

Annotation

Implementation Notes