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(void *data);
  22 static void pmac_backlight_set_legacy_worker(void *data);
  23
  24 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
  25 static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker, NULL);
  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 */
  41 DEFINE_MUTEX(pmac_backlight_mutex);
  42
  43 /* Main backlight storage
  44  *
  45  * Backlight drivers in this variable are required to have the "props"
  46  * attribute set and to have an update_status function.
  47  *
  48  * We can only store one backlight here, but since Apple laptops have only one
  49  * internal display, it doesn't matter. Other backlight drivers can be used
  50  * independently.
  51  *
  52  * Lock ordering:
  53  * pmac_backlight_mutex (global, main backlight)
  54  *   pmac_backlight->sem (backlight class)
  55  */
  56 struct backlight_device *pmac_backlight;
  57
  58 int pmac_has_backlight_type(const char *type)
  59 {
  60         struct device_node* bk_node = find_devices("backlight");
  61
  62         if (bk_node) {
  63                 char *prop = get_property(bk_node, "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(void *data)
  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                 down(&pmac_backlight->sem);
 107                 props = pmac_backlight->props;
 108
 109                 brightness = props->brightness +
 110                         ((pmac_backlight_key_queued?-1:1) *
 111                          (props->max_brightness / 15));
 112
 113                 if (brightness < 0)
 114                         brightness = 0;
 115                 else if (brightness > props->max_brightness)
 116                         brightness = props->max_brightness;
 117
 118                 props->brightness = brightness;
 119                 props->update_status(pmac_backlight);
 120
 121                 up(&pmac_backlight->sem);
 122         }
 123         mutex_unlock(&pmac_backlight_mutex);
 124 }
 125
 126 /* This function is called in interrupt context */
 127 void pmac_backlight_key(int direction)
 128 {
 129         if (atomic_read(&kernel_backlight_disabled))
 130                 return;
 131
 132         /* we can receive multiple interrupts here, but the scheduled work
 133          * will run only once, with the last value
 134          */
 135         pmac_backlight_key_queued = direction;
 136         schedule_work(&pmac_backlight_key_work);
 137 }
 138
 139 static int __pmac_backlight_set_legacy_brightness(int brightness)
 140 {
 141         int error = -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                 props->brightness = brightness *
 150                         (props->max_brightness + 1) /
 151                         (OLD_BACKLIGHT_MAX + 1);
 152
 153                 if (props->brightness > props->max_brightness)
 154                         props->brightness = props->max_brightness;
 155                 else if (props->brightness < 0)
 156                         props->brightness = 0;
 157
 158                 props->update_status(pmac_backlight);
 159                 up(&pmac_backlight->sem);
 160
 161                 error = 0;
 162         }
 163         mutex_unlock(&pmac_backlight_mutex);
 164
 165         return error;
 166 }
 167
 168 static void pmac_backlight_set_legacy_worker(void *data)
 169 {
 170         if (atomic_read(&kernel_backlight_disabled))
 171                 return;
 172
 173         __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
 174 }
 175
 176 /* This function is called in interrupt context */
 177 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
 178         if (atomic_read(&kernel_backlight_disabled))
 179                 return;
 180
 181         pmac_backlight_set_legacy_queued = brightness;
 182         schedule_work(&pmac_backlight_set_legacy_work);
 183 }
 184
 185 int pmac_backlight_set_legacy_brightness(int brightness)
 186 {
 187         return __pmac_backlight_set_legacy_brightness(brightness);
 188 }
 189
 190 int pmac_backlight_get_legacy_brightness()
 191 {
 192         int result = -ENXIO;
 193
 194         mutex_lock(&pmac_backlight_mutex);
 195         if (pmac_backlight) {
 196                 struct backlight_properties *props;
 197
 198                 down(&pmac_backlight->sem);
 199                 props = pmac_backlight->props;
 200
 201                 result = props->brightness *
 202                         (OLD_BACKLIGHT_MAX + 1) /
 203                         (props->max_brightness + 1);
 204
 205                 up(&pmac_backlight->sem);
 206         }
 207         mutex_unlock(&pmac_backlight_mutex);
 208
 209         return result;
 210 }
 211
 212 void pmac_backlight_disable()
 213 {
 214         atomic_inc(&kernel_backlight_disabled);
 215 }
 216
 217 void pmac_backlight_enable()
 218 {
 219         atomic_dec(&kernel_backlight_disabled);
 220 }
 221
 222 EXPORT_SYMBOL_GPL(pmac_backlight);
 223 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
 224 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);