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                 char *prop = get_property(bk_node, "backlight-control", NULL);
  42                 if (prop && strncmp(prop, type, strlen(type)) == 0)
  43                         return 1;
  44         }
  45
  46         return 0;
  47 }
  48
  49 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  50 {
  51         int level = (FB_BACKLIGHT_LEVELS - 1);
  52
  53         if (info && info->bl_dev) {
  54                 int i, max = 0;
  55
  56                 /* Look for biggest value */
  57                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  58                         max = max((int)info->bl_curve[i], max);
  59
  60                 /* Look for nearest value */
  61                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  62                         int diff = abs(info->bl_curve[i] - value);
  63                         if (diff < max) {
  64                                 max = diff;
  65                                 level = i;
  66                         }
  67                 }
  68
  69         }
  70
  71         return level;
  72 }
  73
  74 static void pmac_backlight_key(int direction)
  75 {
  76         mutex_lock(&pmac_backlight_mutex);
  77         if (pmac_backlight) {
  78                 struct backlight_properties *props;
  79                 int brightness;
  80
  81                 down(&pmac_backlight->sem);
  82                 props = pmac_backlight->props;
  83
  84                 brightness = props->brightness +
  85                         ((direction?-1:1) * (props->max_brightness / 15));
  86
  87                 if (brightness < 0)
  88                         brightness = 0;
  89                 else if (brightness > props->max_brightness)
  90                         brightness = props->max_brightness;
  91
  92                 props->brightness = brightness;
  93                 props->update_status(pmac_backlight);
  94
  95                 up(&pmac_backlight->sem);
  96         }
  97         mutex_unlock(&pmac_backlight_mutex);
  98 }
  99
 100 void pmac_backlight_key_up()
 101 {
 102         pmac_backlight_key(0);
 103 }
 104
 105 void pmac_backlight_key_down()
 106 {
 107         pmac_backlight_key(1);
 108 }
 109
 110 int pmac_backlight_set_legacy_brightness(int brightness)
 111 {
 112         int error = -ENXIO;
 113
 114         mutex_lock(&pmac_backlight_mutex);
 115         if (pmac_backlight) {
 116                 struct backlight_properties *props;
 117
 118                 down(&pmac_backlight->sem);
 119                 props = pmac_backlight->props;
 120                 props->brightness = brightness *
 121                         (props->max_brightness + 1) /
 122                         (OLD_BACKLIGHT_MAX + 1);
 123
 124                 if (props->brightness > props->max_brightness)
 125                         props->brightness = props->max_brightness;
 126                 else if (props->brightness < 0)
 127                         props->brightness = 0;
 128
 129                 props->update_status(pmac_backlight);
 130                 up(&pmac_backlight->sem);
 131
 132                 error = 0;
 133         }
 134         mutex_unlock(&pmac_backlight_mutex);
 135
 136         return error;
 137 }
 138
 139 int pmac_backlight_get_legacy_brightness()
 140 {
 141         int result = -ENXIO;
 142
 143         mutex_lock(&pmac_backlight_mutex);
 144         if (pmac_backlight) {
 145                 struct backlight_properties *props;
 146
 147                 down(&pmac_backlight->sem);
 148                 props = pmac_backlight->props;
 149
 150                 result = props->brightness *
 151                         (OLD_BACKLIGHT_MAX + 1) /
 152                         (props->max_brightness + 1);
 153
 154                 up(&pmac_backlight->sem);
 155         }
 156         mutex_unlock(&pmac_backlight_mutex);
 157
 158         return result;
 159 }