/*

 * Copyright (C) 2008 Atmel Corporation

 *

 * Backlight driver using Atmel PWM peripheral.

 *

 * 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/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/fb.h>

#include <linux/clk.h>

#include <linux/gpio.h>

#include <linux/backlight.h>

#include <linux/atmel_pwm.h>

#include <linux/atmel-pwm-bl.h>

struct atmel_pwm_bl {

	const struct atmel_pwm_bl_platform_data	*pdata;

	struct backlight_device			*bldev;

	struct platform_device			*pdev;

	struct pwm_channel			pwmc;

	int					gpio_on;

};

static int atmel_pwm_bl_set_intensity(struct backlight_device *bd)

{

	struct atmel_pwm_bl *pwmbl = bl_get_data(bd);

	int intensity = bd->props.brightness;

	int pwm_duty;

	if (bd->props.power != FB_BLANK_UNBLANK)

		intensity = 0;

	if (bd->props.fb_blank != FB_BLANK_UNBLANK)

		intensity = 0;

	if (pwmbl->pdata->pwm_active_low)

		pwm_duty = pwmbl->pdata->pwm_duty_min + intensity;

	else

		pwm_duty = pwmbl->pdata->pwm_duty_max - intensity;

	if (pwm_duty > pwmbl->pdata->pwm_duty_max)

		pwm_duty = pwmbl->pdata->pwm_duty_max;

	if (pwm_duty < pwmbl->pdata->pwm_duty_min)

		pwm_duty = pwmbl->pdata->pwm_duty_min;

	if (!intensity) {

		if (pwmbl->gpio_on != -1) {

			gpio_set_value(pwmbl->gpio_on,

					0 ^ pwmbl->pdata->on_active_low);

		}

		pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);

		pwm_channel_disable(&pwmbl->pwmc);

	} else {

		pwm_channel_enable(&pwmbl->pwmc);

		pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);

		if (pwmbl->gpio_on != -1) {

			gpio_set_value(pwmbl->gpio_on,

					1 ^ pwmbl->pdata->on_active_low);

		}

	}

	return 0;

}

static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)

{

	struct atmel_pwm_bl *pwmbl = bl_get_data(bd);

	u8 intensity;

	if (pwmbl->pdata->pwm_active_low) {

		intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -

			pwmbl->pdata->pwm_duty_min;

	} else {

		intensity = pwmbl->pdata->pwm_duty_max -

			pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);

	}

	return intensity;

}

static int atmel_pwm_bl_init_pwm(struct atmel_pwm_bl *pwmbl)

{

	unsigned long pwm_rate = pwmbl->pwmc.mck;

	unsigned long prescale = DIV_ROUND_UP(pwm_rate,

			(pwmbl->pdata->pwm_frequency *

			 pwmbl->pdata->pwm_compare_max)) - 1;

	/*

	 * Prescale must be power of two and maximum 0xf in size because of

	 * hardware limit. PWM speed will be:

	 *	PWM module clock speed / (2 ^ prescale).

	 */

	prescale = fls(prescale);

	if (prescale > 0xf)

		prescale = 0xf;

	pwm_channel_writel(&pwmbl->pwmc, PWM_CMR, prescale);

	pwm_channel_writel(&pwmbl->pwmc, PWM_CDTY,

			pwmbl->pdata->pwm_duty_min +

			pwmbl->bldev->props.brightness);

	pwm_channel_writel(&pwmbl->pwmc, PWM_CPRD,

			pwmbl->pdata->pwm_compare_max);

	dev_info(&pwmbl->pdev->dev, "Atmel PWM backlight driver "

			"(%lu Hz)\n", pwmbl->pwmc.mck /

			pwmbl->pdata->pwm_compare_max /

			(1 << prescale));

	return pwm_channel_enable(&pwmbl->pwmc);

}

static struct backlight_ops atmel_pwm_bl_ops = {

	.get_brightness = atmel_pwm_bl_get_intensity,

	.update_status  = atmel_pwm_bl_set_intensity,

};

static int atmel_pwm_bl_probe(struct platform_device *pdev)

{

	const struct atmel_pwm_bl_platform_data *pdata;

	struct backlight_device *bldev;

	struct atmel_pwm_bl *pwmbl;

	int retval;

	pwmbl = kzalloc(sizeof(struct atmel_pwm_bl), GFP_KERNEL);

	if (!pwmbl)

		return -ENOMEM;

	pwmbl->pdev = pdev;

	pdata = pdev->dev.platform_data;

	if (!pdata) {

		retval = -ENODEV;

		goto err_free_mem;

	}

	if (pdata->pwm_compare_max < pdata->pwm_duty_max ||

			pdata->pwm_duty_min > pdata->pwm_duty_max ||

			pdata->pwm_frequency == 0) {

		retval = -EINVAL;

		goto err_free_mem;

	}

	pwmbl->pdata = pdata;

	pwmbl->gpio_on = pdata->gpio_on;

	retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc);

	if (retval)

		goto err_free_mem;

	if (pwmbl->gpio_on != -1) {

		retval = gpio_request(pwmbl->gpio_on, "gpio_atmel_pwm_bl");

		if (retval) {

			pwmbl->gpio_on = -1;

			goto err_free_pwm;

		}

		/* Turn display off by defatult. */

		retval = gpio_direction_output(pwmbl->gpio_on,

				0 ^ pdata->on_active_low);

		if (retval)

			goto err_free_gpio;

	}

	bldev = backlight_device_register("atmel-pwm-bl",

			&pdev->dev, pwmbl, &atmel_pwm_bl_ops);

	if (IS_ERR(bldev)) {

		retval = PTR_ERR(bldev);

		goto err_free_gpio;

	}

	pwmbl->bldev = bldev;

	platform_set_drvdata(pdev, pwmbl);

	/* Power up the backlight by default at middle intesity. */

	bldev->props.power = FB_BLANK_UNBLANK;

	bldev->props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;

	bldev->props.brightness = bldev->props.max_brightness / 2;

	retval = atmel_pwm_bl_init_pwm(pwmbl);

	if (retval)

		goto err_free_bl_dev;

	atmel_pwm_bl_set_intensity(bldev);

	return 0;

err_free_bl_dev:

	platform_set_drvdata(pdev, NULL);

	backlight_device_unregister(bldev);

err_free_gpio:

	if (pwmbl->gpio_on != -1)

		gpio_free(pwmbl->gpio_on);

err_free_pwm:

	pwm_channel_free(&pwmbl->pwmc);

err_free_mem:

	kfree(pwmbl);

	return retval;

}

static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)

{

	struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);

	if (pwmbl->gpio_on != -1) {

		gpio_set_value(pwmbl->gpio_on, 0);

		gpio_free(pwmbl->gpio_on);

	}

	pwm_channel_disable(&pwmbl->pwmc);

	pwm_channel_free(&pwmbl->pwmc);

	backlight_device_unregister(pwmbl->bldev);

	platform_set_drvdata(pdev, NULL);

	kfree(pwmbl);

	return 0;

}

static struct platform_driver atmel_pwm_bl_driver = {

	.driver = {

		.name = "atmel-pwm-bl",

	},

	/* REVISIT add suspend() and resume() */

	.remove = __exit_p(atmel_pwm_bl_remove),

};

static int __init atmel_pwm_bl_init(void)

{

	return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);

}

module_init(atmel_pwm_bl_init);

static void __exit atmel_pwm_bl_exit(void)

{

	platform_driver_unregister(&atmel_pwm_bl_driver);

}

module_exit(atmel_pwm_bl_exit);

MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");

MODULE_DESCRIPTION("Atmel PWM backlight driver");

MODULE_LICENSE("GPL");