/*

 * Backlight driver for Wolfson Microelectronics WM831x PMICs

 *

 * Copyright 2009 Wolfson Microelectonics plc

 *

 * 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/fb.h>

#include <linux/backlight.h>

#include <linux/mfd/wm831x/core.h>

#include <linux/mfd/wm831x/pdata.h>

#include <linux/mfd/wm831x/regulator.h>

struct wm831x_backlight_data {

	struct wm831x *wm831x;

	int isink_reg;

	int current_brightness;

};

static int wm831x_backlight_set(struct backlight_device *bl, int brightness)

{

	struct wm831x_backlight_data *data = bl_get_data(bl);

	struct wm831x *wm831x = data->wm831x;

	int power_up = !data->current_brightness && brightness;

	int power_down = data->current_brightness && !brightness;

	int ret;

	if (power_up) {

		/* Enable the ISINK */

		ret = wm831x_set_bits(wm831x, data->isink_reg,

				      WM831X_CS1_ENA, WM831X_CS1_ENA);

		if (ret < 0)

			goto err;

		/* Enable the DC-DC */

		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,

				      WM831X_DC4_ENA, WM831X_DC4_ENA);

		if (ret < 0)

			goto err;

	}

	if (power_down) {

		/* DCDC first */

		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,

				      WM831X_DC4_ENA, 0);

		if (ret < 0)

			goto err;

		/* ISINK */

		ret = wm831x_set_bits(wm831x, data->isink_reg,

				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);

		if (ret < 0)

			goto err;

	}

	/* Set the new brightness */

	ret = wm831x_set_bits(wm831x, data->isink_reg,

			      WM831X_CS1_ISEL_MASK, brightness);

	if (ret < 0)

		goto err;

	if (power_up) {

		/* Drive current through the ISINK */

		ret = wm831x_set_bits(wm831x, data->isink_reg,

				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);

		if (ret < 0)

			return ret;

	}

	data->current_brightness = brightness;

	return 0;

err:

	/* If we were in the middle of a power transition always shut down

	 * for safety.

	 */

	if (power_up || power_down) {

		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);

		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);

	}

	return ret;

}

static int wm831x_backlight_update_status(struct backlight_device *bl)

{

	int brightness = bl->props.brightness;

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

		brightness = 0;

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

		brightness = 0;

	if (bl->props.state & BL_CORE_SUSPENDED)

		brightness = 0;

	return wm831x_backlight_set(bl, brightness);

}

static int wm831x_backlight_get_brightness(struct backlight_device *bl)

{

	struct wm831x_backlight_data *data = bl_get_data(bl);

	return data->current_brightness;

}

static struct backlight_ops wm831x_backlight_ops = {

	.options = BL_CORE_SUSPENDRESUME,

	.update_status	= wm831x_backlight_update_status,

	.get_brightness	= wm831x_backlight_get_brightness,

};

static int wm831x_backlight_probe(struct platform_device *pdev)

{

	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);

	struct wm831x_pdata *wm831x_pdata;

	struct wm831x_backlight_pdata *pdata;

	struct wm831x_backlight_data *data;

	struct backlight_device *bl;

	int ret, i, max_isel, isink_reg, dcdc_cfg;

	/* We need platform data */

	if (pdev->dev.parent->platform_data) {

		wm831x_pdata = pdev->dev.parent->platform_data;

		pdata = wm831x_pdata->backlight;

	} else {

		pdata = NULL;

	}

	if (!pdata) {

		dev_err(&pdev->dev, "No platform data supplied\n");

		return -EINVAL;

	}

	/* Figure out the maximum current we can use */

	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {

		if (wm831x_isinkv_values[i] > pdata->max_uA)

			break;

	}

	if (i == 0) {

		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);

		return -EINVAL;

	}

	max_isel = i - 1;

	if (pdata->max_uA != wm831x_isinkv_values[max_isel])

		dev_warn(&pdev->dev,

			 "Maximum current is %duA not %duA as requested\n",

			 wm831x_isinkv_values[max_isel], pdata->max_uA);

	switch (pdata->isink) {

	case 1:

		isink_reg = WM831X_CURRENT_SINK_1;

		dcdc_cfg = 0;

		break;

	case 2:

		isink_reg = WM831X_CURRENT_SINK_2;

		dcdc_cfg = WM831X_DC4_FBSRC;

		break;

	default:

		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);

		return -EINVAL;

	}

	/* Configure the ISINK to use for feedback */

	ret = wm831x_reg_unlock(wm831x);

	if (ret < 0)

		return ret;

	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,

			      dcdc_cfg);

	wm831x_reg_lock(wm831x);

	if (ret < 0)

		return ret;

	data = kzalloc(sizeof(*data), GFP_KERNEL);

	if (data == NULL)

		return -ENOMEM;

	data->wm831x = wm831x;

	data->current_brightness = 0;

	data->isink_reg = isink_reg;

	bl = backlight_device_register("wm831x", &pdev->dev,

			data, &wm831x_backlight_ops);

	if (IS_ERR(bl)) {

		dev_err(&pdev->dev, "failed to register backlight\n");

		kfree(data);

		return PTR_ERR(bl);

	}

	bl->props.max_brightness = max_isel;

	bl->props.brightness = max_isel;

	platform_set_drvdata(pdev, bl);

	/* Disable the DCDC if it was started so we can bootstrap */

	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);

	backlight_update_status(bl);

	return 0;

}

static int wm831x_backlight_remove(struct platform_device *pdev)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);

	struct wm831x_backlight_data *data = bl_get_data(bl);

	backlight_device_unregister(bl);

	kfree(data);

	return 0;

}

static struct platform_driver wm831x_backlight_driver = {

	.driver		= {

		.name	= "wm831x-backlight",

		.owner	= THIS_MODULE,

	},

	.probe		= wm831x_backlight_probe,

	.remove		= wm831x_backlight_remove,

};

static int __init wm831x_backlight_init(void)

{

	return platform_driver_register(&wm831x_backlight_driver);

}

module_init(wm831x_backlight_init);

static void __exit wm831x_backlight_exit(void)

{

	platform_driver_unregister(&wm831x_backlight_driver);

}

module_exit(wm831x_backlight_exit);

MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");

MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:wm831x-backlight");