/*
 * 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/slab.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 const 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;
        struct backlight_properties props;
        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;

        props.max_brightness = max_isel;
        bl = backlight_device_register("wm831x", &pdev->dev, data,
                                       &wm831x_backlight_ops, &props);
        if (IS_ERR(bl)) {
                dev_err(&pdev->dev, "failed to register backlight\n");
                kfree(data);
                return PTR_ERR(bl);
        }

        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");