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