/*
 *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
 *  PWM beeper driver
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under  the terms of the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the License, or (at your
 *  option) any later version.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#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_state(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)) {
                error = PTR_ERR(beeper->pwm);
                if (error != -EPROBE_DEFER)
                        dev_err(dev, "Failed to request PWM device: %d\n",
                                error);
                return error;
        }

        /* Sync up PWM state and ensure it is off. */
        pwm_init_state(beeper->pwm, &state);
        state.enabled = false;
        error = pwm_apply_state(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)) {
                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);

        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 __maybe_unused 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 __maybe_unused 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 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     = &pwm_beeper_pm_ops,
                .of_match_table = of_match_ptr(pwm_beeper_match),
        },
};
module_platform_driver(pwm_beeper_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("PWM beeper driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pwm-beeper");