max8925_bl.c

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/*
 * Backlight driver for Maxim MAX8925
 *
 * Copyright (C) 2009 Marvell International Ltd.
 *      Haojian Zhuang <[email protected]>
 *
 * 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/init.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/fb.h>
#include <linux/i2c.h>
#include <linux/backlight.h>
#include <linux/mfd/max8925.h>
#include <linux/slab.h>
#include <linux/module.h>

#define MAX_BRIGHTNESS      (0xff)
#define MIN_BRIGHTNESS      (0)

#define LWX_FREQ(x)     (((x - 601) / 100) & 0x7)

struct max8925_backlight_data {
    struct max8925_chip *chip;

    int current_brightness;
    int reg_mode_cntl;
    int reg_cntl;
};

static int max8925_backlight_set(struct backlight_device *bl, int brightness)
{
    struct max8925_backlight_data *data = bl_get_data(bl);
    struct max8925_chip *chip = data->chip;
    unsigned char value;
    int ret;

    if (brightness > MAX_BRIGHTNESS)
        value = MAX_BRIGHTNESS;
    else
        value = brightness;

    ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
    if (ret < 0)
        goto out;

    if (!data->current_brightness && brightness)
        /* enable WLED output */
        ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
    else if (!brightness)
        /* disable WLED output */
        ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
    if (ret < 0)
        goto out;
    dev_dbg(chip->dev, "set brightness %d\n", value);
    data->current_brightness = value;
    return 0;
out:
    dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
        value, ret);
    return ret;
}

static int max8925_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 max8925_backlight_set(bl, brightness);
}

static int max8925_backlight_get_brightness(struct backlight_device *bl)
{
    struct max8925_backlight_data *data = bl_get_data(bl);
    struct max8925_chip *chip = data->chip;
    int ret;

    ret = max8925_reg_read(chip->i2c, data->reg_cntl);
    if (ret < 0)
        return -EINVAL;
    data->current_brightness = ret;
    dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
    return ret;
}

static const struct backlight_ops max8925_backlight_ops = {
    .options    = BL_CORE_SUSPENDRESUME,
    .update_status  = max8925_backlight_update_status,
    .get_brightness = max8925_backlight_get_brightness,
};

static int __devinit max8925_backlight_probe(struct platform_device *pdev)
{
    struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
    struct max8925_backlight_pdata *pdata = pdev->dev.platform_data;
    struct max8925_backlight_data *data;
    struct backlight_device *bl;
    struct backlight_properties props;
    struct resource *res;
    unsigned char value;
    int ret = 0;

    data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
                GFP_KERNEL);
    if (data == NULL)
        return -ENOMEM;

    res = platform_get_resource(pdev, IORESOURCE_REG, 0);
    if (!res) {
        dev_err(&pdev->dev, "No REG resource for mode control!\n");
        ret = -ENXIO;
        goto out;
    }
    data->reg_mode_cntl = res->start;
    res = platform_get_resource(pdev, IORESOURCE_REG, 1);
    if (!res) {
        dev_err(&pdev->dev, "No REG resource for control!\n");
        ret = -ENXIO;
        goto out;
    }
    data->reg_cntl = res->start;

    data->chip = chip;
    data->current_brightness = 0;

    memset(&props, 0, sizeof(struct backlight_properties));
    props.type = BACKLIGHT_RAW;
    props.max_brightness = MAX_BRIGHTNESS;
    bl = backlight_device_register("max8925-backlight", &pdev->dev, data,
                    &max8925_backlight_ops, &props);
    if (IS_ERR(bl)) {
        dev_err(&pdev->dev, "failed to register backlight\n");
        ret = PTR_ERR(bl);
        goto out;
    }
    bl->props.brightness = MAX_BRIGHTNESS;

    platform_set_drvdata(pdev, bl);

    value = 0;
    if (pdata) {
        if (pdata->lxw_scl)
            value |= (1 << 7);
        if (pdata->lxw_freq)
            value |= (LWX_FREQ(pdata->lxw_freq) << 4);
        if (pdata->dual_string)
            value |= (1 << 1);
    }
    ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
    if (ret < 0)
        goto out_brt;

    backlight_update_status(bl);
    return 0;
out_brt:
    backlight_device_unregister(bl);
out:
    devm_kfree(&pdev->dev, data);
    return ret;
}

static int __devexit max8925_backlight_remove(struct platform_device *pdev)
{
    struct backlight_device *bl = platform_get_drvdata(pdev);

    backlight_device_unregister(bl);
    return 0;
}

static struct platform_driver max8925_backlight_driver = {
    .driver     = {
        .name   = "max8925-backlight",
        .owner  = THIS_MODULE,
    },
    .probe      = max8925_backlight_probe,
    .remove     = __devexit_p(max8925_backlight_remove),
};

module_platform_driver(max8925_backlight_driver);

MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
MODULE_AUTHOR("Haojian Zhuang <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:max8925-backlight");