// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
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* PWM beeper driver
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*/
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#include <linux/input.h>
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#include <linux/regulator/consumer.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/pwm.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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struct pwm_beeper {
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struct input_dev *input;
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struct pwm_device *pwm;
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struct regulator *amplifier;
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struct work_struct work;
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unsigned long period;
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unsigned int bell_frequency;
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bool suspended;
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bool amplifier_on;
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};
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#define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
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static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
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{
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struct pwm_state state;
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int error;
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pwm_get_state(beeper->pwm, &state);
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state.enabled = true;
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state.period = period;
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pwm_set_relative_duty_cycle(&state, 50, 100);
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error = pwm_apply_state(beeper->pwm, &state);
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if (error)
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return error;
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if (!beeper->amplifier_on) {
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error = regulator_enable(beeper->amplifier);
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if (error) {
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pwm_disable(beeper->pwm);
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return error;
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}
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beeper->amplifier_on = true;
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}
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return 0;
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}
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static void pwm_beeper_off(struct pwm_beeper *beeper)
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{
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if (beeper->amplifier_on) {
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regulator_disable(beeper->amplifier);
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beeper->amplifier_on = false;
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}
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pwm_disable(beeper->pwm);
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}
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static void pwm_beeper_work(struct work_struct *work)
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{
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struct pwm_beeper *beeper = container_of(work, struct pwm_beeper, work);
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unsigned long period = READ_ONCE(beeper->period);
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if (period)
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pwm_beeper_on(beeper, period);
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else
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pwm_beeper_off(beeper);
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}
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static int pwm_beeper_event(struct input_dev *input,
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unsigned int type, unsigned int code, int value)
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{
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struct pwm_beeper *beeper = input_get_drvdata(input);
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if (type != EV_SND || value < 0)
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return -EINVAL;
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switch (code) {
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case SND_BELL:
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value = value ? beeper->bell_frequency : 0;
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break;
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case SND_TONE:
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break;
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default:
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return -EINVAL;
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}
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if (value == 0)
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beeper->period = 0;
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else
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beeper->period = HZ_TO_NANOSECONDS(value);
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if (!beeper->suspended)
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schedule_work(&beeper->work);
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return 0;
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}
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static void pwm_beeper_stop(struct pwm_beeper *beeper)
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{
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cancel_work_sync(&beeper->work);
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pwm_beeper_off(beeper);
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}
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static void pwm_beeper_close(struct input_dev *input)
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{
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struct pwm_beeper *beeper = input_get_drvdata(input);
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pwm_beeper_stop(beeper);
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}
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static int pwm_beeper_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct pwm_beeper *beeper;
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struct pwm_state state;
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u32 bell_frequency;
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int error;
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beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
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if (!beeper)
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return -ENOMEM;
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beeper->pwm = devm_pwm_get(dev, NULL);
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if (IS_ERR(beeper->pwm)) {
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error = PTR_ERR(beeper->pwm);
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if (error != -EPROBE_DEFER)
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dev_err(dev, "Failed to request PWM device: %d\n",
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error);
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return error;
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}
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/* Sync up PWM state and ensure it is off. */
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pwm_init_state(beeper->pwm, &state);
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state.enabled = false;
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error = pwm_apply_state(beeper->pwm, &state);
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if (error) {
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dev_err(dev, "failed to apply initial PWM state: %d\n",
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error);
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return error;
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}
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beeper->amplifier = devm_regulator_get(dev, "amp");
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if (IS_ERR(beeper->amplifier)) {
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error = PTR_ERR(beeper->amplifier);
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if (error != -EPROBE_DEFER)
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dev_err(dev, "Failed to get 'amp' regulator: %d\n",
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error);
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return error;
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}
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INIT_WORK(&beeper->work, pwm_beeper_work);
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error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
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if (error) {
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bell_frequency = 1000;
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dev_dbg(dev,
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"failed to parse 'beeper-hz' property, using default: %uHz\n",
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bell_frequency);
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}
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beeper->bell_frequency = bell_frequency;
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beeper->input = devm_input_allocate_device(dev);
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if (!beeper->input) {
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dev_err(dev, "Failed to allocate input device\n");
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return -ENOMEM;
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}
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beeper->input->name = "pwm-beeper";
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beeper->input->phys = "pwm/input0";
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beeper->input->id.bustype = BUS_HOST;
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beeper->input->id.vendor = 0x001f;
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beeper->input->id.product = 0x0001;
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beeper->input->id.version = 0x0100;
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input_set_capability(beeper->input, EV_SND, SND_TONE);
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input_set_capability(beeper->input, EV_SND, SND_BELL);
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beeper->input->event = pwm_beeper_event;
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beeper->input->close = pwm_beeper_close;
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input_set_drvdata(beeper->input, beeper);
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error = input_register_device(beeper->input);
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if (error) {
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dev_err(dev, "Failed to register input device: %d\n", error);
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return error;
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}
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platform_set_drvdata(pdev, beeper);
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return 0;
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}
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static int __maybe_unused pwm_beeper_suspend(struct device *dev)
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{
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struct pwm_beeper *beeper = dev_get_drvdata(dev);
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/*
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* Spinlock is taken here is not to protect write to
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* beeper->suspended, but to ensure that pwm_beeper_event
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* does not re-submit work once flag is set.
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*/
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spin_lock_irq(&beeper->input->event_lock);
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beeper->suspended = true;
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spin_unlock_irq(&beeper->input->event_lock);
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pwm_beeper_stop(beeper);
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return 0;
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}
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static int __maybe_unused pwm_beeper_resume(struct device *dev)
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{
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struct pwm_beeper *beeper = dev_get_drvdata(dev);
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spin_lock_irq(&beeper->input->event_lock);
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beeper->suspended = false;
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spin_unlock_irq(&beeper->input->event_lock);
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/* Let worker figure out if we should resume beeping */
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schedule_work(&beeper->work);
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return 0;
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}
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static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
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pwm_beeper_suspend, pwm_beeper_resume);
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#ifdef CONFIG_OF
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static const struct of_device_id pwm_beeper_match[] = {
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{ .compatible = "pwm-beeper", },
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{ },
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};
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MODULE_DEVICE_TABLE(of, pwm_beeper_match);
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#endif
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static struct platform_driver pwm_beeper_driver = {
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.probe = pwm_beeper_probe,
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.driver = {
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.name = "pwm-beeper",
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.pm = &pwm_beeper_pm_ops,
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.of_match_table = of_match_ptr(pwm_beeper_match),
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},
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};
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module_platform_driver(pwm_beeper_driver);
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MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
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MODULE_DESCRIPTION("PWM beeper driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:pwm-beeper");
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