generic_bl.c

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/*
 *  Generic Backlight Driver
 *
 *  Copyright (c) 2004-2008 Richard Purdie
 *
 *  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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

static int genericbl_intensity;
static struct backlight_device *generic_backlight_device;
static struct generic_bl_info *bl_machinfo;

/* Flag to signal when the battery is low */
#define GENERICBL_BATTLOW       BL_CORE_DRIVER1

static int genericbl_send_intensity(struct backlight_device *bd)
{
    int intensity = bd->props.brightness;

    if (bd->props.power != FB_BLANK_UNBLANK)
        intensity = 0;
    if (bd->props.state & BL_CORE_FBBLANK)
        intensity = 0;
    if (bd->props.state & BL_CORE_SUSPENDED)
        intensity = 0;
    if (bd->props.state & GENERICBL_BATTLOW)
        intensity &= bl_machinfo->limit_mask;

    bl_machinfo->set_bl_intensity(intensity);

    genericbl_intensity = intensity;

    if (bl_machinfo->kick_battery)
        bl_machinfo->kick_battery();

    return 0;
}

static int genericbl_get_intensity(struct backlight_device *bd)
{
    return genericbl_intensity;
}

/*
 * Called when the battery is low to limit the backlight intensity.
 * If limit==0 clear any limit, otherwise limit the intensity
 */
void genericbl_limit_intensity(int limit)
{
    struct backlight_device *bd = generic_backlight_device;

    mutex_lock(&bd->ops_lock);
    if (limit)
        bd->props.state |= GENERICBL_BATTLOW;
    else
        bd->props.state &= ~GENERICBL_BATTLOW;
    backlight_update_status(generic_backlight_device);
    mutex_unlock(&bd->ops_lock);
}
EXPORT_SYMBOL(genericbl_limit_intensity);

static const struct backlight_ops genericbl_ops = {
    .options = BL_CORE_SUSPENDRESUME,
    .get_brightness = genericbl_get_intensity,
    .update_status  = genericbl_send_intensity,
};

static int genericbl_probe(struct platform_device *pdev)
{
    struct backlight_properties props;
    struct generic_bl_info *machinfo = pdev->dev.platform_data;
    const char *name = "generic-bl";
    struct backlight_device *bd;

    bl_machinfo = machinfo;
    if (!machinfo->limit_mask)
        machinfo->limit_mask = -1;

    if (machinfo->name)
        name = machinfo->name;

    memset(&props, 0, sizeof(struct backlight_properties));
    props.type = BACKLIGHT_RAW;
    props.max_brightness = machinfo->max_intensity;
    bd = backlight_device_register(name, &pdev->dev, NULL, &genericbl_ops,
                       &props);
    if (IS_ERR (bd))
        return PTR_ERR (bd);

    platform_set_drvdata(pdev, bd);

    bd->props.power = FB_BLANK_UNBLANK;
    bd->props.brightness = machinfo->default_intensity;
    backlight_update_status(bd);

    generic_backlight_device = bd;

    pr_info("Generic Backlight Driver Initialized.\n");
    return 0;
}

static int genericbl_remove(struct platform_device *pdev)
{
    struct backlight_device *bd = platform_get_drvdata(pdev);

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

    backlight_device_unregister(bd);

    pr_info("Generic Backlight Driver Unloaded\n");
    return 0;
}

static struct platform_driver genericbl_driver = {
    .probe      = genericbl_probe,
    .remove     = genericbl_remove,
    .driver     = {
        .name   = "generic-bl",
    },
};

module_platform_driver(genericbl_driver);

MODULE_AUTHOR("Richard Purdie <[email protected]>");
MODULE_DESCRIPTION("Generic Backlight Driver");
MODULE_LICENSE("GPL");