/*
 * linux/drivers/video/backlight/pwm_bl.c
 *
 * Copyright (C) 2014 Institut de Recherche Technologique SystemX and OpenWide.
 * All rights reserved.
 * Modified by Jimmy Durand Wesolowski <jimmy.durand-wesolowski@openwide.fr>
 * for Xvisor.
 *
 * simple PWM based backlight control, board code has to setup
 * 1) pin configuration so PWM waveforms can output
 * 2) platform_data being correctly configured
 *
 * 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.
 *
 * @file pwm_bl.c
 * @author Jimmy Durand Wesolowski <jimmy.durand-wesolowski@openwide.fr>
 * @brief Blacklight on PWM controller driver
 */

#include <linux/gpio/consumer.h>
#include <linux/gpio.h>
#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/regulator/consumer.h>
#include <linux/slab.h>

#define MODULE_DESC		"PWM based Backlight Driver"
#define MODULE_AUTHOR		"Jimmy Durand Wesolowski"
#define MODULE_LICENSE		"GPL"
#define MODULE_IPRIORITY	1
#define MODULE_INIT		pwm_backlight_driver_init
#define MODULE_EXIT		pwm_backlight_driver_exit

struct pwm_bl_data {
	struct pwm_device	*pwm;
	struct device		*dev;
	unsigned int		period;
	unsigned int		lth_brightness;
	unsigned int		*levels;
	bool			enabled;
	struct regulator	*power_supply;
	struct gpio_desc	*enable_gpio;
	unsigned int		scale;
	int			(*notify)(struct device *,
					  int brightness);
	void			(*notify_after)(struct device *,
					int brightness);
	int			(*check_fb)(struct device *, struct fb_info *);
	void			(*exit)(struct device *);
};

static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
{
	int err;

	if (pb->enabled)
		return;

	err = regulator_enable(pb->power_supply);
	if (err < 0)
		dev_err(pb->dev, "failed to enable power supply\n");

	if (pb->enable_gpio)
		gpiod_set_value(pb->enable_gpio, 1);

	pwm_enable(pb->pwm);
	pb->enabled = true;
}

static void pwm_backlight_power_off(struct pwm_bl_data *pb)
{
	if (!pb->enabled)
		return;

	pwm_config(pb->pwm, 0, pb->period);
	pwm_disable(pb->pwm);

	if (pb->enable_gpio)
		gpiod_set_value(pb->enable_gpio, 0);

	regulator_disable(pb->power_supply);
	pb->enabled = false;
}

static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
{
	unsigned int lth = pb->lth_brightness;
	int duty_cycle;

	if (pb->levels)
		duty_cycle = pb->levels[brightness];
	else
		duty_cycle = brightness;

	return sdiv64(duty_cycle * (pb->period - lth), pb->scale) + lth;
}

static int pwm_backlight_update_status(struct backlight_device *bl)
{
	struct pwm_bl_data *pb = bl_get_data(bl);
	int brightness = bl->props.brightness;
	int duty_cycle;

	if (bl->props.power != FB_BLANK_UNBLANK ||
	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
	    bl->props.state & BL_CORE_FBBLANK)
		brightness = 0;

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

	if (brightness > 0) {
		duty_cycle = compute_duty_cycle(pb, brightness);
		pwm_config(pb->pwm, duty_cycle, pb->period);
		pwm_backlight_power_on(pb, brightness);
	} else
		pwm_backlight_power_off(pb);

	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 = bl_get_data(bl);

	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_parse_dt(struct device *dev,
				  struct platform_pwm_backlight_data *data)
{
	struct device_node *node = dev->of_node;
	struct property *prop;
	int length;
	u32 value;
	int ret;

	if (!node)
		return -ENODEV;

	memset(data, 0, sizeof(*data));

	/* determine the number of brightness levels */
	prop = of_find_property(node, "brightness-levels", &length);
	if (!prop)
		return -EINVAL;

	data->max_brightness = length / sizeof(u32);

	/* read brightness levels from DT property */
	if (data->max_brightness > 0) {
		size_t size = sizeof(*data->levels) * data->max_brightness;

		data->levels = devm_kzalloc(dev, size, GFP_KERNEL);
		if (!data->levels)
			return -ENOMEM;

		ret = of_property_read_u32_array(node, "brightness-levels",
						 data->levels,
						 data->max_brightness);
		if (ret < 0)
			return ret;

		ret = of_property_read_u32(node, "default-brightness-level",
					   &value);
		if (ret < 0)
			return ret;

		data->dft_brightness = value;
		data->max_brightness--;
	}

	return 0;
}

static struct vmm_devtree_nodeid pwm_backlight_of_match[] = {
	{ .compatible = "pwm-backlight" },
	{ }
};

static int pwm_backlight_probe(struct vmm_device *dev)
{
	struct platform_pwm_backlight_data defdata;
	struct platform_pwm_backlight_data *data = &defdata;
	struct backlight_properties props;
	struct backlight_device *bl;
	struct pwm_bl_data *pb;
	int ret;

	ret = pwm_backlight_parse_dt(dev, data);
	if (ret < 0) {
		dev_err(dev, "failed to find platform data\n");
		return ret;
	}

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

	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
	if (!pb) {
		ret = -ENOMEM;
		goto err_alloc;
	}

	if (data->levels) {
		unsigned int i;

		for (i = 0; i <= data->max_brightness; i++)
			if (data->levels[i] > pb->scale)
				pb->scale = data->levels[i];

		pb->levels = data->levels;
	} else
		pb->scale = data->max_brightness;

	pb->notify = data->notify;
	pb->notify_after = data->notify_after;
	pb->check_fb = data->check_fb;
	pb->exit = data->exit;
	pb->dev = dev;
	pb->enabled = false;

	pb->pwm = devm_pwm_get(dev, NULL);
	if (IS_ERR(pb->pwm)) {
		dev_err(dev, "unable to request PWM, trying legacy API\n");

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

	dev_dbg(dev, "got pwm for backlight\n");

	/*
	 * The DT case will set the pwm_period_ns field to 0 and store the
	 * period, parsed from the DT, in the PWM device. For the non-DT case,
	 * set the period from platform data if it has not already been set
	 * via the PWM lookup table.
	 */
	pb->period = pwm_get_period(pb->pwm);

	if (!pb->period && (data->pwm_period_ns > 0)) {
		pb->period = data->pwm_period_ns;
		pwm_set_period(pb->pwm, data->pwm_period_ns);
	}

	pb->lth_brightness = data->lth_brightness * sdiv32(pb->period, pb->scale);

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

	if (data->dft_brightness > data->max_brightness) {
		dev_warn(dev,
			 "invalid default brightness level: %u, using %u\n",
			 data->dft_brightness, data->max_brightness);
		data->dft_brightness = data->max_brightness;
	}

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

	vmm_devdrv_set_data(dev, bl);

	return 0;

err_alloc:
	if (data->exit)
		data->exit(dev);
	return ret;
}

static int pwm_backlight_remove(struct vmm_device *dev)
{
	struct backlight_device *bl = vmm_devdrv_get_data(dev);
	struct pwm_bl_data *pb = bl_get_data(bl);

	backlight_device_unregister(bl);
	pwm_backlight_power_off(pb);

	if (pb->exit)
		pb->exit(dev);

	return 0;
}

#if 0
static void pwm_backlight_shutdown(struct vmm_device *dev)
{
	struct backlight_device *bl = vmm_devdrv_get_data(dev);
	struct pwm_bl_data *pb = bl_get_data(bl);

	pwm_backlight_power_off(pb);
}
#endif /* 0 */

#ifdef CONFIG_PM_SLEEP
static int pwm_backlight_suspend(struct vmm_device *dev)
{
	struct backlight_device *bl = vmm_devdrv_get_data(dev);
	struct pwm_bl_data *pb = bl_get_data(bl);

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

	pwm_backlight_power_off(pb);

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

	return 0;
}

static int pwm_backlight_resume(struct device *dev)
{
	struct backlight_device *bl = vmm_devdrv_get_data(dev);

	backlight_update_status(bl);

	return 0;
}
#endif

#ifdef CONFIG_PM_SLEEP
static const struct dev_pm_ops pwm_backlight_pm_ops = {
	.suspend = pwm_backlight_suspend,
	.resume = pwm_backlight_resume,
	.poweroff = pwm_backlight_suspend,
	.restore = pwm_backlight_resume,
};
#endif

static struct vmm_driver pwm_backlight_driver = {
	.name		= "pwm-backlight",
#if 0
	.pm		= &pwm_backlight_pm_ops,
#endif /* 0 */
	.match_table	= pwm_backlight_of_match,
	.probe		= pwm_backlight_probe,
	.remove		= pwm_backlight_remove,
#if 0
	.shutdown	= pwm_backlight_shutdown,
#endif /* 0 */
};

static int __init pwm_backlight_driver_init(void)
{
	return vmm_devdrv_register_driver(&pwm_backlight_driver);
}

static void __exit pwm_backlight_driver_exit(void)
{
	vmm_devdrv_unregister_driver(&pwm_backlight_driver);
}

VMM_DECLARE_MODULE(MODULE_DESC,
		   MODULE_AUTHOR,
		   MODULE_LICENSE,
		   MODULE_IPRIORITY,
		   MODULE_INIT,
		   MODULE_EXIT);
