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 <linux/adb.h>
  14 #include <linux/pmu.h>
  15 #include <asm/atomic.h>
  16 #include <asm/prom.h>
  17 #include <asm/backlight.h>
  18
  19 #define OLD_BACKLIGHT_MAX 15
  20
  21 static void pmac_backlight_key_worker(struct work_struct *work);
  22 static void pmac_backlight_set_legacy_worker(struct work_struct *work);
  23
  24 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
  25 static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
  26
  27 /* Although these variables are used in interrupt context, it makes no sense to
  28  * protect them. No user is able to produce enough key events per second and
  29  * notice the errors that might happen.
  30  */
  31 static int pmac_backlight_key_queued;
  32 static int pmac_backlight_set_legacy_queued;
  33
  34 /* The via-pmu code allows the backlight to be grabbed, in which case the
  35  * in-kernel control of the brightness needs to be disabled. This should
  36  * only be used by really old PowerBooks.
  37  */
  38 static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
  39
  40 /* Protect the pmac_backlight variable below.
  41    You should hold this lock when using the pmac_backlight pointer to
  42    prevent its potential removal. */
  43 DEFINE_MUTEX(pmac_backlight_mutex);
  44
  45 /* Main backlight storage
  46  *
  47  * Backlight drivers in this variable are required to have the "ops"
  48  * attribute set and to have an update_status function.
  49  *
  50  * We can only store one backlight here, but since Apple laptops have only one
  51  * internal display, it doesn't matter. Other backlight drivers can be used
  52  * independently.
  53  *
  54  */
  55 struct backlight_device *pmac_backlight;
  56
  57 int pmac_has_backlight_type(const char *type)
  58 {
  59         struct device_node* bk_node = find_devices("backlight");
  60
  61         if (bk_node) {
  62                 const char *prop = get_property(bk_node,
  63                                 "backlight-control", NULL);
  64                 if (prop && strncmp(prop, type, strlen(type)) == 0)
  65                         return 1;
  66         }
  67
  68         return 0;
  69 }
  70
  71 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  72 {
  73         int level = (FB_BACKLIGHT_LEVELS - 1);
  74
  75         if (info && info->bl_dev) {
  76                 int i, max = 0;
  77
  78                 /* Look for biggest value */
  79                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  80                         max = max((int)info->bl_curve[i], max);
  81
  82                 /* Look for nearest value */
  83                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  84                         int diff = abs(info->bl_curve[i] - value);
  85                         if (diff < max) {
  86                                 max = diff;
  87                                 level = i;
  88                         }
  89                 }
  90
  91         }
  92
  93         return level;
  94 }
  95
  96 static void pmac_backlight_key_worker(struct work_struct *work)
  97 {
  98         if (atomic_read(&kernel_backlight_disabled))
  99                 return;
 100
 101         mutex_lock(&pmac_backlight_mutex);
 102         if (pmac_backlight) {
 103                 struct backlight_properties *props;
 104                 int brightness;
 105
 106                 props = &pmac_backlight->props;
 107
 108                 brightness = props->brightness +
 109                         ((pmac_backlight_key_queued?-1:1) *
 110                          (props->max_brightness / 15));
 111
 112                 if (brightness < 0)
 113                         brightness = 0;
 114                 else if (brightness > props->max_brightness)
 115                         brightness = props->max_brightness;
 116
 117                 props->brightness = brightness;
 118                 backlight_update_status(pmac_backlight);
 119         }
 120         mutex_unlock(&pmac_backlight_mutex);
 121 }
 122
 123 /* This function is called in interrupt context */
 124 void pmac_backlight_key(int direction)
 125 {
 126         if (atomic_read(&kernel_backlight_disabled))
 127                 return;
 128
 129         /* we can receive multiple interrupts here, but the scheduled work
 130          * will run only once, with the last value
 131          */
 132         pmac_backlight_key_queued = direction;
 133         schedule_work(&pmac_backlight_key_work);
 134 }
 135
 136 static int __pmac_backlight_set_legacy_brightness(int brightness)
 137 {
 138         int error = -ENXIO;
 139
 140         mutex_lock(&pmac_backlight_mutex);
 141         if (pmac_backlight) {
 142                 struct backlight_properties *props;
 143
 144                 props = &pmac_backlight->props;
 145                 props->brightness = brightness *
 146                         (props->max_brightness + 1) /
 147                         (OLD_BACKLIGHT_MAX + 1);
 148
 149                 if (props->brightness > props->max_brightness)
 150                         props->brightness = props->max_brightness;
 151                 else if (props->brightness < 0)
 152                         props->brightness = 0;
 153
 154                 backlight_update_status(pmac_backlight);
 155
 156                 error = 0;
 157         }
 158         mutex_unlock(&pmac_backlight_mutex);
 159
 160         return error;
 161 }
 162
 163 static void pmac_backlight_set_legacy_worker(struct work_struct *work)
 164 {
 165         if (atomic_read(&kernel_backlight_disabled))
 166                 return;
 167
 168         __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
 169 }
 170
 171 /* This function is called in interrupt context */
 172 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
 173         if (atomic_read(&kernel_backlight_disabled))
 174                 return;
 175
 176         pmac_backlight_set_legacy_queued = brightness;
 177         schedule_work(&pmac_backlight_set_legacy_work);
 178 }
 179
 180 int pmac_backlight_set_legacy_brightness(int brightness)
 181 {
 182         return __pmac_backlight_set_legacy_brightness(brightness);
 183 }
 184
 185 int pmac_backlight_get_legacy_brightness()
 186 {
 187         int result = -ENXIO;
 188
 189         mutex_lock(&pmac_backlight_mutex);
 190         if (pmac_backlight) {
 191                 struct backlight_properties *props;
 192
 193                 props = &pmac_backlight->props;
 194
 195                 result = props->brightness *
 196                         (OLD_BACKLIGHT_MAX + 1) /
 197                         (props->max_brightness + 1);
 198         }
 199         mutex_unlock(&pmac_backlight_mutex);
 200
 201         return result;
 202 }
 203
 204 void pmac_backlight_disable()
 205 {
 206         atomic_inc(&kernel_backlight_disabled);
 207 }
 208
 209 void pmac_backlight_enable()
 210 {
 211         atomic_dec(&kernel_backlight_disabled);
 212 }
 213
 214 EXPORT_SYMBOL_GPL(pmac_backlight);
 215 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
 216 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);