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 <linux/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 = of_find_node_by_name(NULL, "backlight");
  60
  61         if (bk_node) {
  62                 const char *prop = of_get_property(bk_node,
  63                                 "backlight-control", NULL);
  64                 if (prop && strncmp(prop, type, strlen(type)) == 0) {
  65                         of_node_put(bk_node);
  66                         return 1;
  67                 }
  68                 of_node_put(bk_node);
  69         }
  70
  71         return 0;
  72 }
  73
  74 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  75 {
  76         int level = (FB_BACKLIGHT_LEVELS - 1);
  77
  78         if (info && info->bl_dev) {
  79                 int i, max = 0;
  80
  81                 /* Look for biggest value */
  82                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  83                         max = max((int)info->bl_curve[i], max);
  84
  85                 /* Look for nearest value */
  86                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  87                         int diff = abs(info->bl_curve[i] - value);
  88                         if (diff < max) {
  89                                 max = diff;
  90                                 level = i;
  91                         }
  92                 }
  93
  94         }
  95
  96         return level;
  97 }
  98
  99 static void pmac_backlight_key_worker(struct work_struct *work)
 100 {
 101         if (atomic_read(&kernel_backlight_disabled))
 102                 return;
 103
 104         mutex_lock(&pmac_backlight_mutex);
 105         if (pmac_backlight) {
 106                 struct backlight_properties *props;
 107                 int brightness;
 108
 109                 props = &pmac_backlight->props;
 110
 111                 brightness = props->brightness +
 112                         ((pmac_backlight_key_queued?-1:1) *
 113                          (props->max_brightness / 15));
 114
 115                 if (brightness < 0)
 116                         brightness = 0;
 117                 else if (brightness > props->max_brightness)
 118                         brightness = props->max_brightness;
 119
 120                 props->brightness = brightness;
 121                 backlight_update_status(pmac_backlight);
 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                 props = &pmac_backlight->props;
 148                 props->brightness = brightness *
 149                         (props->max_brightness + 1) /
 150                         (OLD_BACKLIGHT_MAX + 1);
 151
 152                 if (props->brightness > props->max_brightness)
 153                         props->brightness = props->max_brightness;
 154                 else if (props->brightness < 0)
 155                         props->brightness = 0;
 156
 157                 backlight_update_status(pmac_backlight);
 158
 159                 error = 0;
 160         }
 161         mutex_unlock(&pmac_backlight_mutex);
 162
 163         return error;
 164 }
 165
 166 static void pmac_backlight_set_legacy_worker(struct work_struct *work)
 167 {
 168         if (atomic_read(&kernel_backlight_disabled))
 169                 return;
 170
 171         __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
 172 }
 173
 174 /* This function is called in interrupt context */
 175 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
 176         if (atomic_read(&kernel_backlight_disabled))
 177                 return;
 178
 179         pmac_backlight_set_legacy_queued = brightness;
 180         schedule_work(&pmac_backlight_set_legacy_work);
 181 }
 182
 183 int pmac_backlight_set_legacy_brightness(int brightness)
 184 {
 185         return __pmac_backlight_set_legacy_brightness(brightness);
 186 }
 187
 188 int pmac_backlight_get_legacy_brightness()
 189 {
 190         int result = -ENXIO;
 191
 192         mutex_lock(&pmac_backlight_mutex);
 193         if (pmac_backlight) {
 194                 struct backlight_properties *props;
 195
 196                 props = &pmac_backlight->props;
 197
 198                 result = props->brightness *
 199                         (OLD_BACKLIGHT_MAX + 1) /
 200                         (props->max_brightness + 1);
 201         }
 202         mutex_unlock(&pmac_backlight_mutex);
 203
 204         return result;
 205 }
 206
 207 void pmac_backlight_disable()
 208 {
 209         atomic_inc(&kernel_backlight_disabled);
 210 }
 211
 212 void pmac_backlight_enable()
 213 {
 214         atomic_dec(&kernel_backlight_disabled);
 215 }
 216
 217 EXPORT_SYMBOL_GPL(pmac_backlight);
 218 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
 219 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);