On Wed, Jan 11, 2017 at 02:02:01PM -0600, David Lechner wrote:
> 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@xxxxxxxxxxxxxx>
> ---
> drivers/input/misc/pwm-beeper.c | 29 ++++++++++++++++++++++++++++-
> 1 file changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
> index 30ac227..708e88e 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>
> @@ -25,8 +26,10 @@
> struct pwm_beeper {
> struct input_dev *input;
> struct pwm_device *pwm;
> + struct regulator *reg;
> struct work_struct work;
> unsigned long period;
> + bool reg_enabled;
> };
>
> #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
> @@ -38,8 +41,20 @@ static void __pwm_beeper_set(struct pwm_beeper *beeper)
> if (period) {
> pwm_config(beeper->pwm, period / 2, period);
> pwm_enable(beeper->pwm);
> - } else
> + if (beeper->reg) {
> + int error;
> +
> + error = regulator_enable(beeper->reg);
> + if (!error)
> + beeper->reg_enabled = true;
> + }
> + } else {
> + if (beeper->reg_enabled) {
> + regulator_disable(beeper->reg);
> + beeper->reg_enabled = false;
> + }
> pwm_disable(beeper->pwm);
> + }
> }
>
> static void pwm_beeper_work(struct work_struct *work)
> @@ -82,6 +97,10 @@ static void pwm_beeper_stop(struct pwm_beeper *beeper)
> {
> cancel_work_sync(&beeper->work);
>
> + if (beeper->reg_enabled) {
> + regulator_disable(beeper->reg);
> + beeper->reg_enabled = false;
> + }
> if (beeper->period)
> pwm_disable(beeper->pwm);
> }
> @@ -111,6 +130,14 @@ static int pwm_beeper_probe(struct platform_device *pdev)
> return error;
> }
>
> + beeper->reg = devm_regulator_get_optional(&pdev->dev, "amp");
If you do not use optional regulator then you will not have to check if
you have it or not everywhere: regulator core will give you a dummy that
you can toggle to your heart's content.
> + error = PTR_ERR_OR_ZERO(beeper->reg);
> + if (error) {
> + if (error != -EPROBE_DEFER)
> + dev_err(dev, "Failed to get amp regulator\n");
> + return error;
> + }
> +
> /*
> * FIXME: pwm_apply_args() should be removed when switching to
> * the atomic PWM API.
> --
> 2.7.4
>
Thanks.
--
Dmitry
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