text: /*
   * 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 =
  			dev_get_platdata(&pdev->dev);
  	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");
  