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: David Lechner <david@lechnology.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index 069d594..ad9b231 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -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;
- if (period) {
- pwm_config(beeper->pwm, period / 2, period);
- pwm_enable(beeper->pwm);
- } else
- pwm_disable(beeper->pwm);
+ 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;
+ }
+
+ 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 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 @@
*/
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);