drivers/input/misc/pwm-beeper.c

Source file repositories/reference/linux-study-clean/drivers/input/misc/pwm-beeper.c

File Facts

System
Linux kernel
Corpus path
drivers/input/misc/pwm-beeper.c
Extension
.c
Size
5816 bytes
Lines
254
Domain
Driver Families
Bucket
drivers/input
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 pwm_beeper {
	struct input_dev *input;
	struct pwm_device *pwm;
	struct regulator *amplifier;
	struct work_struct work;
	unsigned long period;
	unsigned int bell_frequency;
	bool suspended;
	bool amplifier_on;
};

#define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))

static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
{
	struct pwm_state state;
	int error;

	pwm_get_state(beeper->pwm, &state);

	state.enabled = true;
	state.period = period;
	pwm_set_relative_duty_cycle(&state, 50, 100);

	error = pwm_apply_might_sleep(beeper->pwm, &state);
	if (error)
		return error;

	if (!beeper->amplifier_on) {
		error = regulator_enable(beeper->amplifier);
		if (error) {
			pwm_disable(beeper->pwm);
			return error;
		}

		beeper->amplifier_on = true;
	}

	return 0;
}

static void pwm_beeper_off(struct pwm_beeper *beeper)
{
	if (beeper->amplifier_on) {
		regulator_disable(beeper->amplifier);
		beeper->amplifier_on = false;
	}

	pwm_disable(beeper->pwm);
}

static void pwm_beeper_work(struct work_struct *work)
{
	struct pwm_beeper *beeper = container_of(work, struct pwm_beeper, work);
	unsigned long period = READ_ONCE(beeper->period);

	if (period)
		pwm_beeper_on(beeper, period);
	else
		pwm_beeper_off(beeper);
}

static int pwm_beeper_event(struct input_dev *input,
			    unsigned int type, unsigned int code, int value)
{
	struct pwm_beeper *beeper = input_get_drvdata(input);

	if (type != EV_SND || value < 0)
		return -EINVAL;

	switch (code) {
	case SND_BELL:
		value = value ? beeper->bell_frequency : 0;
		break;
	case SND_TONE:
		break;
	default:
		return -EINVAL;
	}

	if (value == 0)
		beeper->period = 0;
	else
		beeper->period = HZ_TO_NANOSECONDS(value);

	if (!beeper->suspended)
		schedule_work(&beeper->work);

	return 0;
}

Annotation

Implementation Notes