arch/powerpc/platforms/powermac/backlight.c

   1 /*
   2  * Miscellaneous procedures for dealing with the PowerMac hardware.
   3  * Contains support for the backlight.
   4  *
   5  *   Copyright (C) 2000 Benjamin Herrenschmidt
   6  *   Copyright (C) 2006 Michael Hanselmann <linux-kernel@hansmi.ch>
   7  *
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/fb.h>
  12 #include <linux/backlight.h>
  13 #include <asm/prom.h>
  14 #include <asm/backlight.h>
  15
  16 #define OLD_BACKLIGHT_MAX 15
  17
  18 /* Protect the pmac_backlight variable */
  19 DEFINE_MUTEX(pmac_backlight_mutex);
  20
  21 /* Main backlight storage
  22  *
  23  * Backlight drivers in this variable are required to have the "props"
  24  * attribute set and to have an update_status function.
  25  *
  26  * We can only store one backlight here, but since Apple laptops have only one
  27  * internal display, it doesn't matter. Other backlight drivers can be used
  28  * independently.
  29  *
  30  * Lock ordering:
  31  * pmac_backlight_mutex (global, main backlight)
  32  *   pmac_backlight->sem (backlight class)
  33  */
  34 struct backlight_device *pmac_backlight;
  35
  36 int pmac_has_backlight_type(const char *type)
  37 {
  38         struct device_node* bk_node = find_devices("backlight");
  39
  40         if (bk_node) {
  41                 const char *prop = get_property(bk_node,
  42                                 "backlight-control", NULL);
  43                 if (prop && strncmp(prop, type, strlen(type)) == 0)
  44                         return 1;
  45         }
  46
  47         return 0;
  48 }
  49
  50 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  51 {
  52         int level = (FB_BACKLIGHT_LEVELS - 1);
  53
  54         if (info && info->bl_dev) {
  55                 int i, max = 0;
  56
  57                 /* Look for biggest value */
  58                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  59                         max = max((int)info->bl_curve[i], max);
  60
  61                 /* Look for nearest value */
  62                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  63                         int diff = abs(info->bl_curve[i] - value);
  64                         if (diff < max) {
  65                                 max = diff;
  66                                 level = i;
  67                         }
  68                 }
  69
  70         }
  71
  72         return level;
  73 }
  74
  75 static void pmac_backlight_key(int direction)
  76 {
  77         mutex_lock(&pmac_backlight_mutex);
  78         if (pmac_backlight) {
  79                 struct backlight_properties *props;
  80                 int brightness;
  81
  82                 down(&pmac_backlight->sem);
  83                 props = pmac_backlight->props;
  84
  85                 brightness = props->brightness +
  86                         ((direction?-1:1) * (props->max_brightness / 15));
  87
  88                 if (brightness < 0)
  89                         brightness = 0;
  90                 else if (brightness > props->max_brightness)
  91                         brightness = props->max_brightness;
  92
  93                 props->brightness = brightness;
  94                 props->update_status(pmac_backlight);
  95
  96                 up(&pmac_backlight->sem);
  97         }
  98         mutex_unlock(&pmac_backlight_mutex);
  99 }
 100
 101 void pmac_backlight_key_up()
 102 {
 103         pmac_backlight_key(0);
 104 }
 105
 106 void pmac_backlight_key_down()
 107 {
 108         pmac_backlight_key(1);
 109 }
 110
 111 int pmac_backlight_set_legacy_brightness(int brightness)
 112 {
 113         int error = -ENXIO;
 114
 115         mutex_lock(&pmac_backlight_mutex);
 116         if (pmac_backlight) {
 117                 struct backlight_properties *props;
 118
 119                 down(&pmac_backlight->sem);
 120                 props = pmac_backlight->props;
 121                 props->brightness = brightness *
 122                         (props->max_brightness + 1) /
 123                         (OLD_BACKLIGHT_MAX + 1);
 124
 125                 if (props->brightness > props->max_brightness)
 126                         props->brightness = props->max_brightness;
 127                 else if (props->brightness < 0)
 128                         props->brightness = 0;
 129
 130                 props->update_status(pmac_backlight);
 131                 up(&pmac_backlight->sem);
 132
 133                 error = 0;
 134         }
 135         mutex_unlock(&pmac_backlight_mutex);
 136
 137         return error;
 138 }
 139
 140 int pmac_backlight_get_legacy_brightness()
 141 {
 142         int result = -ENXIO;
 143
 144         mutex_lock(&pmac_backlight_mutex);
 145         if (pmac_backlight) {
 146                 struct backlight_properties *props;
 147
 148                 down(&pmac_backlight->sem);
 149                 props = pmac_backlight->props;
 150
 151                 result = props->brightness *
 152                         (OLD_BACKLIGHT_MAX + 1) /
 153                         (props->max_brightness + 1);
 154
 155                 up(&pmac_backlight->sem);
 156         }
 157         mutex_unlock(&pmac_backlight_mutex);
 158
 159         return result;
 160 }