/*++
	linux/drivers/video/backlight/pwm_bl.c

	Copyright (c) 2013  WonderMedia Technologies, Inc.

	This program is free software: you can redistribute it and/or modify it under the
	terms of the GNU General Public License as published by the Free Software Foundation,
	either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT
	ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
	PARTICULAR PURPOSE.  See the GNU General Public License for more details.
	You should have received a copy of the GNU General Public License along with
	this program.  If not, see <http://www.gnu.org/licenses/>.

	WonderMedia Technologies, Inc.
	10F, 529, Chung-Cheng Road, Hsin-Tien, Taipei 231, R.O.C.
--*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/pwm_backlight.h>
#include <linux/slab.h>

#include <mach/hardware.h>

struct pwm_bl_data {
	struct pwm_device	*pwm;
	struct device		*dev;
	unsigned int		invert;
	unsigned int		period;
	unsigned int		lth_ns;
	unsigned int		hth_ns;
	int			(*notify)(struct device *,
					  int brightness);
	void			(*notify_after)(struct device *,
					int brightness);
	int			(*check_fb)(struct device *, struct fb_info *);
};

static inline void __pwm0_gpio_setup(void)
{
	/* select pwm function */
	REG8_VAL(GPIO_CTRL_GP20_PWM0_BYTE_ADDR) &= ~0x1;

	/* pwm0 output enable */
	REG8_VAL(GPIO_OD_GP20_PWM0_BYTE_ADDR) &= ~0x01;

	/* share pin */
	REG32_VAL(PIN_SHARING_SEL_4BYTE_ADDR) &= ~0x1000;
}

static int pwm_backlight_update_status(struct backlight_device *bl)
{
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
	int brightness = bl->props.brightness;
	int max = bl->props.max_brightness;

//	if (bl->props.power != FB_BLANK_UNBLANK)
//		brightness = 0;
//
//	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
//		brightness = 0;

	if (pb->notify)
		brightness = pb->notify(pb->dev, brightness);

	if (brightness == 0) {
		if (pb->invert) {
			pwm_config(pb->pwm, pb->period, pb->period);
		} else {
			pwm_config(pb->pwm, 0, pb->period);
			pwm_disable(pb->pwm);
		}
	} else {
		brightness = pb->lth_ns +
			(brightness * (pb->period - pb->lth_ns - pb->hth_ns) / max);
		if (pb->invert)
			brightness = pb->period - brightness;
		pwm_config(pb->pwm, brightness, pb->period);
		pwm_enable(pb->pwm);
	}

	if (pb->notify_after)
		pb->notify_after(pb->dev, brightness);

	return 0;
}

static int pwm_backlight_get_brightness(struct backlight_device *bl)
{
	return bl->props.brightness;
}

static int pwm_backlight_check_fb(struct backlight_device *bl,
				  struct fb_info *info)
{
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	return !pb->check_fb || pb->check_fb(pb->dev, info);
}

static const struct backlight_ops pwm_backlight_ops = {
	.update_status	= pwm_backlight_update_status,
	.get_brightness	= pwm_backlight_get_brightness,
	.check_fb	= pwm_backlight_check_fb,
};

static int pwm_backlight_probe(struct platform_device *pdev)
{
	struct backlight_properties props;
	struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
	struct backlight_device *bl;
	struct pwm_bl_data *pb;
	int ret;

	if (!data) {
		dev_err(&pdev->dev, "failed to find platform data\n");
		return -EINVAL;
	}

	if (data->init) {
		ret = data->init(&pdev->dev);
		if (ret < 0)
			return ret;
	}

	pb = devm_kzalloc(&pdev->dev, sizeof(*pb), GFP_KERNEL);
	if (!pb) {
		dev_err(&pdev->dev, "no memory for state\n");
		ret = -ENOMEM;
		goto err_alloc;
	}

	__pwm0_gpio_setup();

	pb->invert = data->invert;
	pb->period = data->pwm_period_ns;
	pb->notify = data->notify;
	pb->notify_after = data->notify_after;
	pb->check_fb = data->check_fb;
	pb->lth_ns = data->lth_brightness * (data->pwm_period_ns / data->max_brightness);
	pb->hth_ns = (data->max_brightness - data->hth_brightness) *
			(data->pwm_period_ns / data->max_brightness);
	pb->dev = &pdev->dev;

	pb->pwm = pwm_request(data->pwm_id, "backlight");
	if (IS_ERR(pb->pwm)) {
		dev_err(&pdev->dev, "unable to request PWM for backlight\n");
		ret = PTR_ERR(pb->pwm);
		goto err_alloc;
	} else
		dev_dbg(&pdev->dev, "got pwm for backlight\n");

	memset(&props, 0, sizeof(struct backlight_properties));
	props.type = BACKLIGHT_RAW;
	props.max_brightness = data->max_brightness;
	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
				       &pwm_backlight_ops, &props);
	if (IS_ERR(bl)) {
		dev_err(&pdev->dev, "failed to register backlight\n");
		ret = PTR_ERR(bl);
		goto err_bl;
	}

	bl->props.brightness = data->dft_brightness;
	//backlight_update_status(bl);

	platform_set_drvdata(pdev, bl);
	return 0;

err_bl:
	pwm_free(pb->pwm);
err_alloc:
	if (data->exit)
		data->exit(&pdev->dev);
	return ret;
}

static int pwm_backlight_remove(struct platform_device *pdev)
{
	struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
	struct backlight_device *bl = platform_get_drvdata(pdev);
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	backlight_device_unregister(bl);
	pwm_config(pb->pwm, 0, pb->period);
	pwm_disable(pb->pwm);
	pwm_free(pb->pwm);
	if (data->exit)
		data->exit(&pdev->dev);
	return 0;
}

#ifdef CONFIG_PM
static int pwm_backlight_suspend(struct device *dev)
{
	struct backlight_device *bl = dev_get_drvdata(dev);
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	if (pb->notify)
		pb->notify(pb->dev, 0);

	if (pb->invert) {
		pwm_config(pb->pwm, pb->period, pb->period);
	} else {
		pwm_config(pb->pwm, 0, pb->period);
		pwm_disable(pb->pwm);
	}

	if (pb->notify_after)
		pb->notify_after(pb->dev, 0);
	return 0;
}

static int pwm_backlight_resume(struct device *dev)
{
	//struct backlight_device *bl = dev_get_drvdata(dev);
	//backlight_update_status(bl);

	__pwm0_gpio_setup();
	return 0;
}

static SIMPLE_DEV_PM_OPS(pwm_backlight_pm_ops, pwm_backlight_suspend,
			 pwm_backlight_resume);

#endif

static void pwm_backlight_shutdown(struct platform_device *pdev)
{
	pwm_backlight_suspend(&pdev->dev);
}

static struct platform_driver pwm_backlight_driver = {
	.driver		= {
		.name	= "pwm-backlight",
		.owner	= THIS_MODULE,
#ifdef CONFIG_PM
		.pm	= &pwm_backlight_pm_ops,
#endif
	},
	.probe		= pwm_backlight_probe,
	.remove		= pwm_backlight_remove,
	.shutdown	= pwm_backlight_shutdown,
};

module_platform_driver(pwm_backlight_driver);

MODULE_DESCRIPTION("PWM based Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pwm-backlight");