/*
   * LEDs driver for LT3593 controllers
   *
   * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
   *
   * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
   *
   * Based on leds-gpio.c,
   *
   *   Copyright (C) 2007 8D Technologies inc.
   *   Raphael Assenat <raph@8d.com>
   *   Copyright (C) 2008 Freescale Semiconductor, Inc.
   *
   * 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/kernel.h>

  #include <linux/platform_device.h>
  #include <linux/leds.h>

  #include <linux/delay.h>
  #include <linux/gpio.h>

  #include <linux/slab.h>

  #include <linux/module.h>

  
  struct lt3593_led_data {
  	struct led_classdev cdev;
  	unsigned gpio;

  };

  static int lt3593_led_set(struct led_classdev *led_cdev,
  			   enum led_brightness value)

  {

  	struct lt3593_led_data *led_dat =

  		container_of(led_cdev, struct lt3593_led_data, cdev);
  	int pulses;

  
  	/*
  	 * The LT3593 resets its internal current level register to the maximum
  	 * level on the first falling edge on the control pin. Each following
  	 * falling edge decreases the current level by 625uA. Up to 32 pulses
  	 * can be sent, so the maximum power reduction is 20mA.
  	 * After a timeout of 128us, the value is taken from the register and
  	 * applied is to the output driver.
  	 */

  	if (value == 0) {

  		gpio_set_value_cansleep(led_dat->gpio, 0);

  		return 0;

  	}

  	pulses = 32 - (value * 32) / 255;

  
  	if (pulses == 0) {
  		gpio_set_value_cansleep(led_dat->gpio, 0);
  		mdelay(1);
  		gpio_set_value_cansleep(led_dat->gpio, 1);

  		return 0;

  	}
  
  	gpio_set_value_cansleep(led_dat->gpio, 1);
  
  	while (pulses--) {
  		gpio_set_value_cansleep(led_dat->gpio, 0);
  		udelay(1);
  		gpio_set_value_cansleep(led_dat->gpio, 1);
  		udelay(1);
  	}

  	return 0;

  }

  static int create_lt3593_led(const struct gpio_led *template,

  	struct lt3593_led_data *led_dat, struct device *parent)
  {
  	int ret, state;
  
  	/* skip leds on GPIOs that aren't available */
  	if (!gpio_is_valid(template->gpio)) {

  		dev_info(parent, "%s: skipping unavailable LT3593 LED at gpio %d (%s)
  ",

  				KBUILD_MODNAME, template->gpio, template->name);
  		return 0;
  	}

  	led_dat->cdev.name = template->name;
  	led_dat->cdev.default_trigger = template->default_trigger;
  	led_dat->gpio = template->gpio;

  	led_dat->cdev.brightness_set_blocking = lt3593_led_set;

  
  	state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
  	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
  
  	if (!template->retain_state_suspended)
  		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;

  	ret = devm_gpio_request_one(parent, template->gpio, state ?
  				    GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
  				    template->name);

  	if (ret < 0)

  		return ret;

  	ret = led_classdev_register(parent, &led_dat->cdev);
  	if (ret < 0)

  		return ret;

  	dev_info(parent, "%s: registered LT3593 LED '%s' at GPIO %d
  ",

  		KBUILD_MODNAME, template->name, template->gpio);
  
  	return 0;

  }
  
  static void delete_lt3593_led(struct lt3593_led_data *led)
  {
  	if (!gpio_is_valid(led->gpio))
  		return;
  
  	led_classdev_unregister(&led->cdev);

  }

  static int lt3593_led_probe(struct platform_device *pdev)

  {

  	struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);

  	struct lt3593_led_data *leds_data;
  	int i, ret = 0;
  
  	if (!pdata)
  		return -EBUSY;

  	leds_data = devm_kzalloc(&pdev->dev,
  			sizeof(struct lt3593_led_data) * pdata->num_leds,
  			GFP_KERNEL);

  	if (!leds_data)
  		return -ENOMEM;
  
  	for (i = 0; i < pdata->num_leds; i++) {
  		ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
  				      &pdev->dev);
  		if (ret < 0)
  			goto err;
  	}
  
  	platform_set_drvdata(pdev, leds_data);
  
  	return 0;
  
  err:
  	for (i = i - 1; i >= 0; i--)
  		delete_lt3593_led(&leds_data[i]);

  	return ret;
  }

  static int lt3593_led_remove(struct platform_device *pdev)

  {
  	int i;

  	struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);

  	struct lt3593_led_data *leds_data;
  
  	leds_data = platform_get_drvdata(pdev);
  
  	for (i = 0; i < pdata->num_leds; i++)
  		delete_lt3593_led(&leds_data[i]);

  	return 0;
  }
  
  static struct platform_driver lt3593_led_driver = {
  	.probe		= lt3593_led_probe,

  	.remove		= lt3593_led_remove,

  	.driver		= {
  		.name	= "leds-lt3593",

  	},
  };

  module_platform_driver(lt3593_led_driver);

  
  MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
  MODULE_DESCRIPTION("LED driver for LT3593 controllers");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:leds-lt3593");