/*
 * 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/init.h>
#include <linux/platform_device.h>
#include <linux/leds.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/gpio.h>

struct lt3593_led_data {
        struct led_classdev cdev;
        unsigned gpio;
        struct work_struct work;
        u8 new_level;
};

static void lt3593_led_work(struct work_struct *work)
{
        int pulses;
        struct lt3593_led_data *led_dat =
                container_of(work, struct lt3593_led_data, work);

        /*
         * 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 (led_dat->new_level == 0) {
                gpio_set_value_cansleep(led_dat->gpio, 0);
                return;
        }

        pulses = 32 - (led_dat->new_level * 32) / 255;

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

        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);
        }
}

static void 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);

        led_dat->new_level = value;
        schedule_work(&led_dat->work);
}

static int __devinit 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)) {
                printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
                                KBUILD_MODNAME, template->gpio, template->name);
                return 0;
        }

        ret = gpio_request(template->gpio, template->name);
        if (ret < 0)
                return ret;

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

        led_dat->cdev.brightness_set = 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 = gpio_direction_output(led_dat->gpio, state);
        if (ret < 0)
                goto err;

        INIT_WORK(&led_dat->work, lt3593_led_work);

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

        printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
                KBUILD_MODNAME, template->name, template->gpio);

        return 0;

err:
        gpio_free(led_dat->gpio);
        return ret;
}

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

        led_classdev_unregister(&led->cdev);
        cancel_work_sync(&led->work);
        gpio_free(led->gpio);
}

static int __devinit lt3593_led_probe(struct platform_device *pdev)
{
        struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
        struct lt3593_led_data *leds_data;
        int i, ret = 0;

        if (!pdata)
                return -EBUSY;

        leds_data = kzalloc(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]);

        kfree(leds_data);

        return ret;
}

static int __devexit lt3593_led_remove(struct platform_device *pdev)
{
        int i;
        struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
        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]);

        kfree(leds_data);

        return 0;
}

static struct platform_driver lt3593_led_driver = {
        .probe          = lt3593_led_probe,
        .remove         = __devexit_p(lt3593_led_remove),
        .driver         = {
                .name   = "leds-lt3593",
                .owner  = THIS_MODULE,
        },
};

MODULE_ALIAS("platform:leds-lt3593");

static int __init lt3593_led_init(void)
{
        return platform_driver_register(&lt3593_led_driver);
}

static void __exit lt3593_led_exit(void)
{
        platform_driver_unregister(&lt3593_led_driver);
}

module_init(lt3593_led_init);
module_exit(lt3593_led_exit);

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