aat2870_bl.c

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/*
 * linux/drivers/video/backlight/aat2870_bl.c
 *
 * Copyright (c) 2011, NVIDIA Corporation.
 * Author: Jin Park <[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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/mfd/aat2870.h>

struct aat2870_bl_driver_data {
    struct platform_device *pdev;
    struct backlight_device *bd;

    int channels;
    int max_current;
    int brightness; /* current brightness */
};

static inline int aat2870_brightness(struct aat2870_bl_driver_data *aat2870_bl,
                     int brightness)
{
    struct backlight_device *bd = aat2870_bl->bd;
    int val;

    val = brightness * (aat2870_bl->max_current - 1);
    val /= bd->props.max_brightness;

    return val;
}

static inline int aat2870_bl_enable(struct aat2870_bl_driver_data *aat2870_bl)
{
    struct aat2870_data *aat2870
            = dev_get_drvdata(aat2870_bl->pdev->dev.parent);

    return aat2870->write(aat2870, AAT2870_BL_CH_EN,
                  (u8)aat2870_bl->channels);
}

static inline int aat2870_bl_disable(struct aat2870_bl_driver_data *aat2870_bl)
{
    struct aat2870_data *aat2870
            = dev_get_drvdata(aat2870_bl->pdev->dev.parent);

    return aat2870->write(aat2870, AAT2870_BL_CH_EN, 0x0);
}

static int aat2870_bl_get_brightness(struct backlight_device *bd)
{
    return bd->props.brightness;
}

static int aat2870_bl_update_status(struct backlight_device *bd)
{
    struct aat2870_bl_driver_data *aat2870_bl = dev_get_drvdata(&bd->dev);
    struct aat2870_data *aat2870 =
            dev_get_drvdata(aat2870_bl->pdev->dev.parent);
    int brightness = bd->props.brightness;
    int ret;

    if ((brightness < 0) || (bd->props.max_brightness < brightness)) {
        dev_err(&bd->dev, "invalid brightness, %d\n", brightness);
        return -EINVAL;
    }

    dev_dbg(&bd->dev, "brightness=%d, power=%d, state=%d\n",
         bd->props.brightness, bd->props.power, bd->props.state);

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

    ret = aat2870->write(aat2870, AAT2870_BLM,
                 (u8)aat2870_brightness(aat2870_bl, brightness));
    if (ret < 0)
        return ret;

    if (brightness == 0) {
        ret = aat2870_bl_disable(aat2870_bl);
        if (ret < 0)
            return ret;
    } else if (aat2870_bl->brightness == 0) {
        ret = aat2870_bl_enable(aat2870_bl);
        if (ret < 0)
            return ret;
    }

    aat2870_bl->brightness = brightness;

    return 0;
}

static int aat2870_bl_check_fb(struct backlight_device *bd, struct fb_info *fi)
{
    return 1;
}

static const struct backlight_ops aat2870_bl_ops = {
    .options = BL_CORE_SUSPENDRESUME,
    .get_brightness = aat2870_bl_get_brightness,
    .update_status = aat2870_bl_update_status,
    .check_fb = aat2870_bl_check_fb,
};

static int aat2870_bl_probe(struct platform_device *pdev)
{
    struct aat2870_bl_platform_data *pdata = pdev->dev.platform_data;
    struct aat2870_bl_driver_data *aat2870_bl;
    struct backlight_device *bd;
    struct backlight_properties props;
    int ret = 0;

    if (!pdata) {
        dev_err(&pdev->dev, "No platform data\n");
        ret = -ENXIO;
        goto out;
    }

    if (pdev->id != AAT2870_ID_BL) {
        dev_err(&pdev->dev, "Invalid device ID, %d\n", pdev->id);
        ret = -EINVAL;
        goto out;
    }

    aat2870_bl = devm_kzalloc(&pdev->dev,
                  sizeof(struct aat2870_bl_driver_data),
                  GFP_KERNEL);
    if (!aat2870_bl) {
        dev_err(&pdev->dev,
            "Failed to allocate memory for aat2870 backlight\n");
        ret = -ENOMEM;
        goto out;
    }

    memset(&props, 0, sizeof(struct backlight_properties));

    props.type = BACKLIGHT_RAW;
    bd = backlight_device_register("aat2870-backlight", &pdev->dev,
                       aat2870_bl, &aat2870_bl_ops, &props);
    if (IS_ERR(bd)) {
        dev_err(&pdev->dev,
            "Failed allocate memory for backlight device\n");
        ret = PTR_ERR(bd);
        goto out;
    }

    aat2870_bl->pdev = pdev;
    platform_set_drvdata(pdev, aat2870_bl);

    aat2870_bl->bd = bd;

    if (pdata->channels > 0)
        aat2870_bl->channels = pdata->channels;
    else
        aat2870_bl->channels = AAT2870_BL_CH_ALL;

    if (pdata->max_current > 0)
        aat2870_bl->max_current = pdata->max_current;
    else
        aat2870_bl->max_current = AAT2870_CURRENT_27_9;

    if (pdata->max_brightness > 0)
        bd->props.max_brightness = pdata->max_brightness;
    else
        bd->props.max_brightness = 255;

    aat2870_bl->brightness = 0;
    bd->props.power = FB_BLANK_UNBLANK;
    bd->props.brightness = bd->props.max_brightness;

    ret = aat2870_bl_update_status(bd);
    if (ret < 0) {
        dev_err(&pdev->dev, "Failed to initialize\n");
        goto out_bl_dev_unregister;
    }

    return 0;

out_bl_dev_unregister:
    backlight_device_unregister(bd);
out:
    return ret;
}

static int aat2870_bl_remove(struct platform_device *pdev)
{
    struct aat2870_bl_driver_data *aat2870_bl = platform_get_drvdata(pdev);
    struct backlight_device *bd = aat2870_bl->bd;

    bd->props.power = FB_BLANK_POWERDOWN;
    bd->props.brightness = 0;
    backlight_update_status(bd);

    backlight_device_unregister(bd);

    return 0;
}

static struct platform_driver aat2870_bl_driver = {
    .driver = {
        .name   = "aat2870-backlight",
        .owner  = THIS_MODULE,
    },
    .probe      = aat2870_bl_probe,
    .remove     = aat2870_bl_remove,
};

static int __init aat2870_bl_init(void)
{
    return platform_driver_register(&aat2870_bl_driver);
}
subsys_initcall(aat2870_bl_init);

static void __exit aat2870_bl_exit(void)
{
    platform_driver_unregister(&aat2870_bl_driver);
}
module_exit(aat2870_bl_exit);

MODULE_DESCRIPTION("AnalogicTech AAT2870 Backlight");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jin Park <[email protected]>");