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 static void pmac_backlight_key_worker(void *data);
  19 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
  20
  21 /* Although this variable is used in interrupt context, it makes no sense to
  22  * protect it. No user is able to produce enough key events per second and
  23  * notice the errors that might happen.
  24  */
  25 static int pmac_backlight_key_queued;
  26
  27 /* Protect the pmac_backlight variable */
  28 DEFINE_MUTEX(pmac_backlight_mutex);
  29
  30 /* Main backlight storage
  31  *
  32  * Backlight drivers in this variable are required to have the "props"
  33  * attribute set and to have an update_status function.
  34  *
  35  * We can only store one backlight here, but since Apple laptops have only one
  36  * internal display, it doesn't matter. Other backlight drivers can be used
  37  * independently.
  38  *
  39  * Lock ordering:
  40  * pmac_backlight_mutex (global, main backlight)
  41  *   pmac_backlight->sem (backlight class)
  42  */
  43 struct backlight_device *pmac_backlight;
  44
  45 int pmac_has_backlight_type(const char *type)
  46 {
  47         struct device_node* bk_node = find_devices("backlight");
  48
  49         if (bk_node) {
  50                 char *prop = get_property(bk_node, "backlight-control", NULL);
  51                 if (prop && strncmp(prop, type, strlen(type)) == 0)
  52                         return 1;
  53         }
  54
  55         return 0;
  56 }
  57
  58 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  59 {
  60         int level = (FB_BACKLIGHT_LEVELS - 1);
  61
  62         if (info && info->bl_dev) {
  63                 int i, max = 0;
  64
  65                 /* Look for biggest value */
  66                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  67                         max = max((int)info->bl_curve[i], max);
  68
  69                 /* Look for nearest value */
  70                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  71                         int diff = abs(info->bl_curve[i] - value);
  72                         if (diff < max) {
  73                                 max = diff;
  74                                 level = i;
  75                         }
  76                 }
  77
  78         }
  79
  80         return level;
  81 }
  82
  83 static void pmac_backlight_key_worker(void *data)
  84 {
  85         mutex_lock(&pmac_backlight_mutex);
  86         if (pmac_backlight) {
  87                 struct backlight_properties *props;
  88                 int brightness;
  89
  90                 down(&pmac_backlight->sem);
  91                 props = pmac_backlight->props;
  92
  93                 brightness = props->brightness +
  94                         ((pmac_backlight_key_queued?-1:1) *
  95                          (props->max_brightness / 15));
  96
  97                 if (brightness < 0)
  98                         brightness = 0;
  99                 else if (brightness > props->max_brightness)
 100                         brightness = props->max_brightness;
 101
 102                 props->brightness = brightness;
 103                 props->update_status(pmac_backlight);
 104
 105                 up(&pmac_backlight->sem);
 106         }
 107         mutex_unlock(&pmac_backlight_mutex);
 108 }
 109
 110 void pmac_backlight_key(int direction)
 111 {
 112         /* we can receive multiple interrupts here, but the scheduled work
 113          * will run only once, with the last value
 114          */
 115         pmac_backlight_key_queued = direction;
 116         schedule_work(&pmac_backlight_key_work);
 117 }
 118
 119 int pmac_backlight_set_legacy_brightness(int brightness)
 120 {
 121         int error = -ENXIO;
 122
 123         mutex_lock(&pmac_backlight_mutex);
 124         if (pmac_backlight) {
 125                 struct backlight_properties *props;
 126
 127                 down(&pmac_backlight->sem);
 128                 props = pmac_backlight->props;
 129                 props->brightness = brightness *
 130                         (props->max_brightness + 1) /
 131                         (OLD_BACKLIGHT_MAX + 1);
 132
 133                 if (props->brightness > props->max_brightness)
 134                         props->brightness = props->max_brightness;
 135                 else if (props->brightness < 0)
 136                         props->brightness = 0;
 137
 138                 props->update_status(pmac_backlight);
 139                 up(&pmac_backlight->sem);
 140
 141                 error = 0;
 142         }
 143         mutex_unlock(&pmac_backlight_mutex);
 144
 145         return error;
 146 }
 147
 148 int pmac_backlight_get_legacy_brightness()
 149 {
 150         int result = -ENXIO;
 151
 152         mutex_lock(&pmac_backlight_mutex);
 153         if (pmac_backlight) {
 154                 struct backlight_properties *props;
 155
 156                 down(&pmac_backlight->sem);
 157                 props = pmac_backlight->props;
 158
 159                 result = props->brightness *
 160                         (OLD_BACKLIGHT_MAX + 1) /
 161                         (props->max_brightness + 1);
 162
 163                 up(&pmac_backlight->sem);
 164         }
 165         mutex_unlock(&pmac_backlight_mutex);
 166
 167         return result;
 168 }
 169
 170 EXPORT_SYMBOL_GPL(pmac_backlight);
 171 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
 172 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);