leds-regulator.c

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/*
 * leds-regulator.c - LED class driver for regulator driven LEDs.
 *
 * Copyright (C) 2009 Antonio Ospite <[email protected]>
 *
 * 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 __devinit 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 __devexit 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 = __devexit_p(regulator_led_remove),
};

module_platform_driver(regulator_led_driver);

MODULE_AUTHOR("Antonio Ospite <[email protected]>");
MODULE_DESCRIPTION("Regulator driven LED driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-regulator");