wm831x_bl.c

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/*
 * 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/module.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 = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
    if (data == NULL)
        return -ENOMEM;

    data->wm831x = wm831x;
    data->current_brightness = 0;
    data->isink_reg = isink_reg;

    memset(&props, 0, sizeof(props));
    props.type = BACKLIGHT_RAW;
    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");
        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);

    backlight_device_unregister(bl);
    return 0;
}

static struct platform_driver wm831x_backlight_driver = {
    .driver     = {
        .name   = "wm831x-backlight",
        .owner  = THIS_MODULE,
    },
    .probe      = wm831x_backlight_probe,
    .remove     = wm831x_backlight_remove,
};

module_platform_driver(wm831x_backlight_driver);

MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
MODULE_AUTHOR("Mark Brown <[email protected]");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-backlight");