/*
 * leds-regulator.c - LED class driver for regulator driven LEDs.
 *
 * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
 *
 * Inspired by leds-wm8350 driver.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/leds.h>
#include <linux/leds-regulator.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

#define to_regulator_led(led_cdev) \
        container_of(led_cdev, struct regulator_led, cdev)

struct regulator_led {
        struct led_classdev cdev;
        enum led_brightness value;
        int enabled;
        struct mutex mutex;
        struct work_struct work;

        struct regulator *vcc;
};

static inline int led_regulator_get_max_brightness(struct regulator *supply)
{
        int ret;
        int voltage = regulator_list_voltage(supply, 0);

        if (voltage <= 0)
                return 1;

        /* even if regulator can't change voltages,
         * we still assume it can change status
         * and the LED can be turned on and off.
         */
        ret = regulator_set_voltage(supply, voltage, voltage);
        if (ret < 0)
                return 1;

        return regulator_count_voltages(supply);
}

static int led_regulator_get_voltage(struct regulator *supply,
                enum led_brightness brightness)
{
        if (brightness == 0)
                return -EINVAL;

        return regulator_list_voltage(supply, brightness - 1);
}


static void regulator_led_enable(struct regulator_led *led)
{
        int ret;

        if (led->enabled)
                return;

        ret = regulator_enable(led->vcc);
        if (ret != 0) {
                dev_err(led->cdev.dev, "Failed to enable vcc: %d\n", ret);
                return;
        }

        led->enabled = 1;
}

static void regulator_led_disable(struct regulator_led *led)
{
        int ret;

        if (!led->enabled)
                return;

        ret = regulator_disable(led->vcc);
        if (ret != 0) {
                dev_err(led->cdev.dev, "Failed to disable vcc: %d\n", ret);
                return;
        }

        led->enabled = 0;
}

static void regulator_led_set_value(struct regulator_led *led)
{
        int voltage;
        int ret;

        mutex_lock(&led->mutex);

        if (led->value == LED_OFF) {
                regulator_led_disable(led);
                goto out;
        }

        if (led->cdev.max_brightness > 1) {
                voltage = led_regulator_get_voltage(led->vcc, led->value);
                dev_dbg(led->cdev.dev, "brightness: %d voltage: %d\n",
                                led->value, voltage);

                ret = regulator_set_voltage(led->vcc, voltage, voltage);
                if (ret != 0)
                        dev_err(led->cdev.dev, "Failed to set voltage %d: %d\n",
                                voltage, ret);
        }

        regulator_led_enable(led);

out:
        mutex_unlock(&led->mutex);
}

static void led_work(struct work_struct *work)
{
        struct regulator_led *led;

        led = container_of(work, struct regulator_led, work);
        regulator_led_set_value(led);
}

static void regulator_led_brightness_set(struct led_classdev *led_cdev,
                           enum led_brightness value)
{
        struct regulator_led *led = to_regulator_led(led_cdev);

        led->value = value;
        schedule_work(&led->work);
}

static int regulator_led_probe(struct platform_device *pdev)
{
        struct led_regulator_platform_data *pdata = pdev->dev.platform_data;
        struct regulator_led *led;
        struct regulator *vcc;
        int ret = 0;

        if (pdata == NULL) {
                dev_err(&pdev->dev, "no platform data\n");
                return -ENODEV;
        }

        vcc = regulator_get_exclusive(&pdev->dev, "vled");
        if (IS_ERR(vcc)) {
                dev_err(&pdev->dev, "Cannot get vcc for %s\n", pdata->name);
                return PTR_ERR(vcc);
        }

        led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
        if (led == NULL) {
                ret = -ENOMEM;
                goto err_vcc;
        }

        led->cdev.max_brightness = led_regulator_get_max_brightness(vcc);
        if (pdata->brightness > led->cdev.max_brightness) {
                dev_err(&pdev->dev, "Invalid default brightness %d\n",
                                pdata->brightness);
                ret = -EINVAL;
                goto err_vcc;
        }
        led->value = pdata->brightness;

        led->cdev.brightness_set = regulator_led_brightness_set;
        led->cdev.name = pdata->name;
        led->cdev.flags |= LED_CORE_SUSPENDRESUME;
        led->vcc = vcc;

        /* to handle correctly an already enabled regulator */
        if (regulator_is_enabled(led->vcc))
                led->enabled = 1;

        mutex_init(&led->mutex);
        INIT_WORK(&led->work, led_work);

        platform_set_drvdata(pdev, led);

        ret = led_classdev_register(&pdev->dev, &led->cdev);
        if (ret < 0) {
                cancel_work_sync(&led->work);
                goto err_vcc;
        }

        /* to expose the default value to userspace */
        led->cdev.brightness = led->value;

        /* Set the default led status */
        regulator_led_set_value(led);

        return 0;

err_vcc:
        regulator_put(vcc);
        return ret;
}

static int regulator_led_remove(struct platform_device *pdev)
{
        struct regulator_led *led = platform_get_drvdata(pdev);

        led_classdev_unregister(&led->cdev);
        cancel_work_sync(&led->work);
        regulator_led_disable(led);
        regulator_put(led->vcc);
        return 0;
}

static struct platform_driver regulator_led_driver = {
        .driver = {
                   .name  = "leds-regulator",
                   .owner = THIS_MODULE,
                   },
        .probe  = regulator_led_probe,
        .remove = regulator_led_remove,
};

module_platform_driver(regulator_led_driver);

MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
MODULE_DESCRIPTION("Regulator driven LED driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-regulator");