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Commit 9e549244 authored by David Lechner's avatar David Lechner Committed by Dmitry Torokhov
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Input: pwm-beeper - add optional amplifier regulator 



This adds an optional regulator to the pwm-beeper device. This regulator
acts as an amplifier. The amplifier is only enabled while beeping in order
to reduce power consumption.

Tested on LEGO MINDSTORMS EV3, which has a speaker connected to PWM through
an amplifier.

Signed-off-by: default avatarDavid Lechner <david@lechnology.com>
Acked-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 62481881

Documentation/devicetree/bindings/input/pwm-beeper.txt

+16 −0
Original line number Diff line number Diff line
@@ -5,3 +5,19 @@ Registers a PWM device as beeper. 
Required properties:

- compatible: should be "pwm-beeper"

- pwms: phandle to the physical PWM device



Optional properties:

- amp-supply: phandle to a regulator that acts as an amplifier for the beeper



Example:



beeper_amp: amplifier {

	compatible = "fixed-regulator";

	gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;

};



beeper {

	compatible = "pwm-beeper";

	pwms = <&pwm0>;

	amp-supply = <&beeper_amp>;

};

drivers/input/misc/pwm-beeper.c

+50 −13
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
 */



#include <linux/input.h>

#include <linux/regulator/consumer.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/of.h>
@@ -25,30 +26,59 @@ 
struct pwm_beeper {

	struct input_dev *input;

	struct pwm_device *pwm;

	struct regulator *amplifier;

	struct work_struct work;

	unsigned long period;

	bool suspended;

	bool amplifier_on;

};



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



static void __pwm_beeper_set(struct pwm_beeper *beeper)

static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)

{

	unsigned long period = beeper->period;

	int error;



	error = pwm_config(beeper->pwm, period / 2, period);

	if (error)

		return error;



	error = pwm_enable(beeper->pwm);

	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;

	}



	if (period) {

		pwm_config(beeper->pwm, period / 2, period);

		pwm_enable(beeper->pwm);

	} else

	pwm_disable(beeper->pwm);

}



static void pwm_beeper_work(struct work_struct *work)

{

	struct pwm_beeper *beeper =

		container_of(work, struct pwm_beeper, work);

	struct pwm_beeper *beeper = container_of(work, struct pwm_beeper, work);

	unsigned long period = READ_ONCE(beeper->period);



	__pwm_beeper_set(beeper);

	if (period)

		pwm_beeper_on(beeper, period);

	else

		pwm_beeper_off(beeper);

}



static int pwm_beeper_event(struct input_dev *input,
@@ -83,9 +113,7 @@ static int pwm_beeper_event(struct input_dev *input, 
static void pwm_beeper_stop(struct pwm_beeper *beeper)

{

	cancel_work_sync(&beeper->work);



	if (beeper->period)

		pwm_disable(beeper->pwm);

	pwm_beeper_off(beeper);

}



static void pwm_beeper_close(struct input_dev *input)
@@ -120,6 +148,15 @@ static int pwm_beeper_probe(struct platform_device *pdev) 
	 */

	pwm_apply_args(beeper->pwm);



	beeper->amplifier = devm_regulator_get(dev, "amp");

	if (IS_ERR(beeper->amplifier)) {

		error = PTR_ERR(beeper->amplifier);

		if (error != -EPROBE_DEFER)

			dev_err(dev, "Failed to get 'amp' regulator: %d\n",

				error);

		return error;

	}



	INIT_WORK(&beeper->work, pwm_beeper_work);



	beeper->input = devm_input_allocate_device(dev);