drivers/video/backlight/generic_bl.c

   1 /*
   2  *  Generic Backlight Driver
   3  *
   4  *  Copyright (c) 2004-2008 Richard Purdie
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/mutex.h>
  19 #include <linux/fb.h>
  20 #include <linux/backlight.h>
  21
  22 static int genericbl_intensity;
  23 static struct backlight_device *generic_backlight_device;
  24 static struct generic_bl_info *bl_machinfo;
  25
  26 /* Flag to signal when the battery is low */
  27 #define GENERICBL_BATTLOW       BL_CORE_DRIVER1
  28
  29 static int genericbl_send_intensity(struct backlight_device *bd)
  30 {
  31         int intensity = bd->props.brightness;
  32
  33         if (bd->props.power != FB_BLANK_UNBLANK)
  34                 intensity = 0;
  35         if (bd->props.state & BL_CORE_FBBLANK)
  36                 intensity = 0;
  37         if (bd->props.state & BL_CORE_SUSPENDED)
  38                 intensity = 0;
  39         if (bd->props.state & GENERICBL_BATTLOW)
  40                 intensity &= bl_machinfo->limit_mask;
  41
  42         bl_machinfo->set_bl_intensity(intensity);
  43
  44         genericbl_intensity = intensity;
  45
  46         if (bl_machinfo->kick_battery)
  47                 bl_machinfo->kick_battery();
  48
  49         return 0;
  50 }
  51
  52 static int genericbl_get_intensity(struct backlight_device *bd)
  53 {
  54         return genericbl_intensity;
  55 }
  56
  57 /*
  58  * Called when the battery is low to limit the backlight intensity.
  59  * If limit==0 clear any limit, otherwise limit the intensity
  60  */
  61 void genericbl_limit_intensity(int limit)
  62 {
  63         struct backlight_device *bd = generic_backlight_device;
  64
  65         mutex_lock(&bd->ops_lock);
  66         if (limit)
  67                 bd->props.state |= GENERICBL_BATTLOW;
  68         else
  69                 bd->props.state &= ~GENERICBL_BATTLOW;
  70         backlight_update_status(generic_backlight_device);
  71         mutex_unlock(&bd->ops_lock);
  72 }
  73 EXPORT_SYMBOL(genericbl_limit_intensity);
  74
  75 static const struct backlight_ops genericbl_ops = {
  76         .options = BL_CORE_SUSPENDRESUME,
  77         .get_brightness = genericbl_get_intensity,
  78         .update_status  = genericbl_send_intensity,
  79 };
  80
  81 static int genericbl_probe(struct platform_device *pdev)
  82 {
  83         struct backlight_properties props;
  84         struct generic_bl_info *machinfo = pdev->dev.platform_data;
  85         const char *name = "generic-bl";
  86         struct backlight_device *bd;
  87
  88         bl_machinfo = machinfo;
  89         if (!machinfo->limit_mask)
  90                 machinfo->limit_mask = -1;
  91
  92         if (machinfo->name)
  93                 name = machinfo->name;
  94
  95         memset(&props, 0, sizeof(struct backlight_properties));
  96         props.type = BACKLIGHT_RAW;
  97         props.max_brightness = machinfo->max_intensity;
  98         bd = backlight_device_register(name, &pdev->dev, NULL, &genericbl_ops,
  99                                        &props);
 100         if (IS_ERR(bd))
 101                 return PTR_ERR(bd);
 102
 103         platform_set_drvdata(pdev, bd);
 104
 105         bd->props.power = FB_BLANK_UNBLANK;
 106         bd->props.brightness = machinfo->default_intensity;
 107         backlight_update_status(bd);
 108
 109         generic_backlight_device = bd;
 110
 111         pr_info("Generic Backlight Driver Initialized.\n");
 112         return 0;
 113 }
 114
 115 static int genericbl_remove(struct platform_device *pdev)
 116 {
 117         struct backlight_device *bd = platform_get_drvdata(pdev);
 118
 119         bd->props.power = 0;
 120         bd->props.brightness = 0;
 121         backlight_update_status(bd);
 122
 123         backlight_device_unregister(bd);
 124
 125         pr_info("Generic Backlight Driver Unloaded\n");
 126         return 0;
 127 }
 128
 129 static struct platform_driver genericbl_driver = {
 130         .probe          = genericbl_probe,
 131         .remove         = genericbl_remove,
 132         .driver         = {
 133                 .name   = "generic-bl",
 134         },
 135 };
 136
 137 module_platform_driver(genericbl_driver);
 138
 139 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 140 MODULE_DESCRIPTION("Generic Backlight Driver");
 141 MODULE_LICENSE("GPL");