arch/powerpc/platforms/powermac/backlight.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Miscellaneous procedures for dealing with the PowerMac hardware.
   4  * Contains support for the backlight.
   5  *
   6  *   Copyright (C) 2000 Benjamin Herrenschmidt
   7  *   Copyright (C) 2006 Michael Hanselmann <linux-kernel@hansmi.ch>
   8  *
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/fb.h>
  13 #include <linux/backlight.h>
  14 #include <linux/adb.h>
  15 #include <linux/pmu.h>
  16 #include <linux/atomic.h>
  17 #include <linux/export.h>
  18 #include <asm/prom.h>
  19 #include <asm/backlight.h>
  20
  21 #define OLD_BACKLIGHT_MAX 15
  22
  23 static void pmac_backlight_key_worker(struct work_struct *work);
  24 static void pmac_backlight_set_legacy_worker(struct work_struct *work);
  25
  26 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
  27 static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
  28
  29 /* Although these variables are used in interrupt context, it makes no sense to
  30  * protect them. No user is able to produce enough key events per second and
  31  * notice the errors that might happen.
  32  */
  33 static int pmac_backlight_key_queued;
  34 static int pmac_backlight_set_legacy_queued;
  35
  36 /* The via-pmu code allows the backlight to be grabbed, in which case the
  37  * in-kernel control of the brightness needs to be disabled. This should
  38  * only be used by really old PowerBooks.
  39  */
  40 static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
  41
  42 /* Protect the pmac_backlight variable below.
  43    You should hold this lock when using the pmac_backlight pointer to
  44    prevent its potential removal. */
  45 DEFINE_MUTEX(pmac_backlight_mutex);
  46
  47 /* Main backlight storage
  48  *
  49  * Backlight drivers in this variable are required to have the "ops"
  50  * attribute set and to have an update_status function.
  51  *
  52  * We can only store one backlight here, but since Apple laptops have only one
  53  * internal display, it doesn't matter. Other backlight drivers can be used
  54  * independently.
  55  *
  56  */
  57 struct backlight_device *pmac_backlight;
  58
  59 int pmac_has_backlight_type(const char *type)
  60 {
  61         struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
  62
  63         if (bk_node) {
  64                 const char *prop = of_get_property(bk_node,
  65                                 "backlight-control", NULL);
  66                 if (prop && strncmp(prop, type, strlen(type)) == 0) {
  67                         of_node_put(bk_node);
  68                         return 1;
  69                 }
  70                 of_node_put(bk_node);
  71         }
  72
  73         return 0;
  74 }
  75
  76 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
  77 {
  78         int level = (FB_BACKLIGHT_LEVELS - 1);
  79
  80         if (info && info->bl_dev) {
  81                 int i, max = 0;
  82
  83                 /* Look for biggest value */
  84                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
  85                         max = max((int)info->bl_curve[i], max);
  86
  87                 /* Look for nearest value */
  88                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
  89                         int diff = abs(info->bl_curve[i] - value);
  90                         if (diff < max) {
  91                                 max = diff;
  92                                 level = i;
  93                         }
  94                 }
  95
  96         }
  97
  98         return level;
  99 }
 100
 101 static void pmac_backlight_key_worker(struct work_struct *work)
 102 {
 103         if (atomic_read(&kernel_backlight_disabled))
 104                 return;
 105
 106         mutex_lock(&pmac_backlight_mutex);
 107         if (pmac_backlight) {
 108                 struct backlight_properties *props;
 109                 int brightness;
 110
 111                 props = &pmac_backlight->props;
 112
 113                 brightness = props->brightness +
 114                         ((pmac_backlight_key_queued?-1:1) *
 115                          (props->max_brightness / 15));
 116
 117                 if (brightness < 0)
 118                         brightness = 0;
 119                 else if (brightness > props->max_brightness)
 120                         brightness = props->max_brightness;
 121
 122                 props->brightness = brightness;
 123                 backlight_update_status(pmac_backlight);
 124         }
 125         mutex_unlock(&pmac_backlight_mutex);
 126 }
 127
 128 /* This function is called in interrupt context */
 129 void pmac_backlight_key(int direction)
 130 {
 131         if (atomic_read(&kernel_backlight_disabled))
 132                 return;
 133
 134         /* we can receive multiple interrupts here, but the scheduled work
 135          * will run only once, with the last value
 136          */
 137         pmac_backlight_key_queued = direction;
 138         schedule_work(&pmac_backlight_key_work);
 139 }
 140
 141 static int __pmac_backlight_set_legacy_brightness(int brightness)
 142 {
 143         int error = -ENXIO;
 144
 145         mutex_lock(&pmac_backlight_mutex);
 146         if (pmac_backlight) {
 147                 struct backlight_properties *props;
 148
 149                 props = &pmac_backlight->props;
 150                 props->brightness = brightness *
 151                         (props->max_brightness + 1) /
 152                         (OLD_BACKLIGHT_MAX + 1);
 153
 154                 if (props->brightness > props->max_brightness)
 155                         props->brightness = props->max_brightness;
 156                 else if (props->brightness < 0)
 157                         props->brightness = 0;
 158
 159                 backlight_update_status(pmac_backlight);
 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(struct work_struct *work)
 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(void)
 191 {
 192         int result = -ENXIO;
 193
 194         mutex_lock(&pmac_backlight_mutex);
 195         if (pmac_backlight) {
 196                 struct backlight_properties *props;
 197
 198                 props = &pmac_backlight->props;
 199
 200                 result = props->brightness *
 201                         (OLD_BACKLIGHT_MAX + 1) /
 202                         (props->max_brightness + 1);
 203         }
 204         mutex_unlock(&pmac_backlight_mutex);
 205
 206         return result;
 207 }
 208
 209 void pmac_backlight_disable(void)
 210 {
 211         atomic_inc(&kernel_backlight_disabled);
 212 }
 213
 214 void pmac_backlight_enable(void)
 215 {
 216         atomic_dec(&kernel_backlight_disabled);
 217 }
 218
 219 EXPORT_SYMBOL_GPL(pmac_backlight);
 220 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
 221 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);