| Message ID | 1483670635-25060-4-git-send-email-david@lechnology.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jan 6, 2017 at 4:43 AM, David Lechner <david@lechnology.com> wrote: > This adds an optional enable gpio to the pwm-beeper device. This gpio is > used in cases where the beeper needs to be switched on before using it. Isn't it a property of pin muxing? > For > example, there may be an amplifier that is not always powered on. This looks like GPIO based fixed voltage regulator. > > Tested on LEGO MINDSTORMS EV3, which has a speaker connected to PWM through > an amplifier. The amplifier has an enable pin that is connected to a gpio.
On 01/06/2017 11:28 AM, Andy Shevchenko wrote: > On Fri, Jan 6, 2017 at 4:43 AM, David Lechner <david@lechnology.com> wrote: >> This adds an optional enable gpio to the pwm-beeper device. This gpio is >> used in cases where the beeper needs to be switched on before using it. > > Isn't it a property of pin muxing? You may want to turn if off when not making a sound to save power. > >> For >> example, there may be an amplifier that is not always powered on. > > This looks like GPIO based fixed voltage regulator. Yes, I think a regulator could work here just as well. > >> >> Tested on LEGO MINDSTORMS EV3, which has a speaker connected to PWM through >> an amplifier. The amplifier has an enable pin that is connected to a gpio. > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c index e76b710..4379ceb 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/gpio/consumer.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/of.h> @@ -25,6 +26,7 @@ struct pwm_beeper { struct input_dev *input; struct pwm_device *pwm; + struct gpio_desc *enable_gpio; struct work_struct work; unsigned long period; }; @@ -38,8 +40,13 @@ 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->enable_gpio) + gpiod_direction_output(beeper->enable_gpio, 1); + } else { + if (beeper->enable_gpio) + gpiod_direction_output(beeper->enable_gpio, 0); pwm_disable(beeper->pwm); + } } static void pwm_beeper_work(struct work_struct *work) @@ -82,6 +89,8 @@ static void pwm_beeper_stop(struct pwm_beeper *beeper) { cancel_work_sync(&beeper->work); + if (beeper->enable_gpio) + gpiod_direction_output(beeper->enable_gpio, 0); if (beeper->period) pwm_disable(beeper->pwm); } @@ -116,6 +125,15 @@ static int pwm_beeper_probe(struct platform_device *pdev) goto err_free; } + beeper->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", + GPIOD_OUT_LOW); + error = PTR_ERR_OR_ZERO(beeper->enable_gpio); + if (error) { + if (error != -EPROBE_DEFER) + dev_err(&pdev->dev, "Failed to get enable gpio\n"); + goto err_pwm_free; + } + /* * FIXME: pwm_apply_args() should be removed when switching to * the atomic PWM API.
This adds an optional enable gpio to the pwm-beeper device. This gpio is used in cases where the beeper needs to be switched on before using it. For example, there may be an amplifier that is not always powered on. Tested on LEGO MINDSTORMS EV3, which has a speaker connected to PWM through an amplifier. The amplifier has an enable pin that is connected to a gpio. Signed-off-by: David Lechner <david@lechnology.com> --- drivers/input/misc/pwm-beeper.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)