// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2010, Lars-Peter Clausen <[email protected]>
* PWM beeper driver
*/
#include <linux/input.h>
#include <linux/regulator/consumer.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
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;
}
static void pwm_beeper_stop(struct pwm_beeper *beeper)
{
cancel_work_sync(&beeper->work);
pwm_beeper_off(beeper);
}
static void pwm_beeper_close(struct input_dev *input)
{
struct pwm_beeper *beeper = input_get_drvdata(input);
pwm_beeper_stop(beeper);
}
static int pwm_beeper_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct pwm_beeper *beeper;
struct pwm_state state;
u32 bell_frequency;
int error;
beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
if (!beeper)
return -ENOMEM;
beeper->pwm = devm_pwm_get(dev, NULL);
if (IS_ERR(beeper->pwm))
return dev_err_probe(dev, PTR_ERR(beeper->pwm), "Failed to request PWM device\n");
/* Sync up PWM state and ensure it is off. */
pwm_init_state(beeper->pwm, &state);
state.enabled = false;
error = pwm_apply_might_sleep(beeper->pwm, &state);
if (error) {
dev_err(dev, "failed to apply initial PWM state: %d\n",
error);
return error;
}
beeper->amplifier = devm_regulator_get(dev, "amp");
if (IS_ERR(beeper->amplifier))
return dev_err_probe(dev, PTR_ERR(beeper->amplifier),
"Failed to get 'amp' regulator\n");
INIT_WORK(&beeper->work, pwm_beeper_work);
error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
if (error) {
bell_frequency = 1000;
dev_dbg(dev,
"failed to parse 'beeper-hz' property, using default: %uHz\n",
bell_frequency);
}
beeper->bell_frequency = bell_frequency;
beeper->input = devm_input_allocate_device(dev);
if (!beeper->input) {
dev_err(dev, "Failed to allocate input device\n");
return -ENOMEM;
}
beeper->input->name = "pwm-beeper";
beeper->input->phys = "pwm/input0";
beeper->input->id.bustype = BUS_HOST;
beeper->input->id.vendor = 0x001f;
beeper->input->id.product = 0x0001;
beeper->input->id.version = 0x0100;
input_set_capability(beeper->input, EV_SND, SND_TONE);
input_set_capability(beeper->input, EV_SND, SND_BELL);
beeper->input->event = pwm_beeper_event;
beeper->input->close = pwm_beeper_close;
input_set_drvdata(beeper->input, beeper);
error = input_register_device(beeper->input);
if (error) {
dev_err(dev, "Failed to register input device: %d\n", error);
return error;
}
platform_set_drvdata(pdev, beeper);
return 0;
}
static int pwm_beeper_suspend(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
/*
* Spinlock is taken here is not to protect write to
* beeper->suspended, but to ensure that pwm_beeper_event
* does not re-submit work once flag is set.
*/
spin_lock_irq(&beeper->input->event_lock);
beeper->suspended = true;
spin_unlock_irq(&beeper->input->event_lock);
pwm_beeper_stop(beeper);
return 0;
}
static int pwm_beeper_resume(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
spin_lock_irq(&beeper->input->event_lock);
beeper->suspended = false;
spin_unlock_irq(&beeper->input->event_lock);
/* Let worker figure out if we should resume beeping */
schedule_work(&beeper->work);
return 0;
}
static DEFINE_SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
pwm_beeper_suspend, pwm_beeper_resume);
#ifdef CONFIG_OF
static const struct of_device_id pwm_beeper_match[] = {
{ .compatible = "pwm-beeper", },
{ },
};
MODULE_DEVICE_TABLE(of, pwm_beeper_match);
#endif
static struct platform_driver pwm_beeper_driver = {
.probe = pwm_beeper_probe,
.driver = {
.name = "pwm-beeper",
.pm = pm_sleep_ptr(&pwm_beeper_pm_ops),
.of_match_table = of_match_ptr(pwm_beeper_match),
},
};
module_platform_driver(pwm_beeper_driver);
MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
MODULE_DESCRIPTION("PWM beeper driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pwm-beeper");
Codebase Browser
linux