drivers/video/backlight/backlight.c

   1 /*
   2  * Backlight Lowlevel Control Abstraction
   3  *
   4  * Copyright (C) 2003,2004 Hewlett-Packard Company
   5  *
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/device.h>
  11 #include <linux/backlight.h>
  12 #include <linux/notifier.h>
  13 #include <linux/ctype.h>
  14 #include <linux/err.h>
  15 #include <linux/fb.h>
  16 #include <linux/slab.h>
  17
  18 #ifdef CONFIG_PMAC_BACKLIGHT
  19 #include <asm/backlight.h>
  20 #endif
  21
  22 static const char *const backlight_types[] = {
  23         [BACKLIGHT_RAW] = "raw",
  24         [BACKLIGHT_PLATFORM] = "platform",
  25         [BACKLIGHT_FIRMWARE] = "firmware",
  26 };
  27
  28 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
  29                            defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
  30 /* This callback gets called when something important happens inside a
  31  * framebuffer driver. We're looking if that important event is blanking,
  32  * and if it is, we're switching backlight power as well ...
  33  */
  34 static int fb_notifier_callback(struct notifier_block *self,
  35                                 unsigned long event, void *data)
  36 {
  37         struct backlight_device *bd;
  38         struct fb_event *evdata = data;
  39
  40         /* If we aren't interested in this event, skip it immediately ... */
  41         if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
  42                 return 0;
  43
  44         bd = container_of(self, struct backlight_device, fb_notif);
  45         mutex_lock(&bd->ops_lock);
  46         if (bd->ops)
  47                 if (!bd->ops->check_fb ||
  48                     bd->ops->check_fb(bd, evdata->info)) {
  49                         bd->props.fb_blank = *(int *)evdata->data;
  50                         if (bd->props.fb_blank == FB_BLANK_UNBLANK)
  51                                 bd->props.state &= ~BL_CORE_FBBLANK;
  52                         else
  53                                 bd->props.state |= BL_CORE_FBBLANK;
  54                         backlight_update_status(bd);
  55                 }
  56         mutex_unlock(&bd->ops_lock);
  57         return 0;
  58 }
  59
  60 static int backlight_register_fb(struct backlight_device *bd)
  61 {
  62         memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
  63         bd->fb_notif.notifier_call = fb_notifier_callback;
  64
  65         return fb_register_client(&bd->fb_notif);
  66 }
  67
  68 static void backlight_unregister_fb(struct backlight_device *bd)
  69 {
  70         fb_unregister_client(&bd->fb_notif);
  71 }
  72 #else
  73 static inline int backlight_register_fb(struct backlight_device *bd)
  74 {
  75         return 0;
  76 }
  77
  78 static inline void backlight_unregister_fb(struct backlight_device *bd)
  79 {
  80 }
  81 #endif /* CONFIG_FB */
  82
  83 static void backlight_generate_event(struct backlight_device *bd,
  84                                      enum backlight_update_reason reason)
  85 {
  86         char *envp[2];
  87
  88         switch (reason) {
  89         case BACKLIGHT_UPDATE_SYSFS:
  90                 envp[0] = "SOURCE=sysfs";
  91                 break;
  92         case BACKLIGHT_UPDATE_HOTKEY:
  93                 envp[0] = "SOURCE=hotkey";
  94                 break;
  95         default:
  96                 envp[0] = "SOURCE=unknown";
  97                 break;
  98         }
  99         envp[1] = NULL;
 100         kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
 101         sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
 102 }
 103
 104 static ssize_t backlight_show_power(struct device *dev,
 105                 struct device_attribute *attr,char *buf)
 106 {
 107         struct backlight_device *bd = to_backlight_device(dev);
 108
 109         return sprintf(buf, "%d\n", bd->props.power);
 110 }
 111
 112 static ssize_t backlight_store_power(struct device *dev,
 113                 struct device_attribute *attr, const char *buf, size_t count)
 114 {
 115         int rc;
 116         struct backlight_device *bd = to_backlight_device(dev);
 117         unsigned long power;
 118
 119         rc = strict_strtoul(buf, 0, &power);
 120         if (rc)
 121                 return rc;
 122
 123         rc = -ENXIO;
 124         mutex_lock(&bd->ops_lock);
 125         if (bd->ops) {
 126                 pr_debug("backlight: set power to %lu\n", power);
 127                 if (bd->props.power != power) {
 128                         bd->props.power = power;
 129                         backlight_update_status(bd);
 130                 }
 131                 rc = count;
 132         }
 133         mutex_unlock(&bd->ops_lock);
 134
 135         return rc;
 136 }
 137
 138 static ssize_t backlight_show_brightness(struct device *dev,
 139                 struct device_attribute *attr, char *buf)
 140 {
 141         struct backlight_device *bd = to_backlight_device(dev);
 142
 143         return sprintf(buf, "%d\n", bd->props.brightness);
 144 }
 145
 146 static ssize_t backlight_store_brightness(struct device *dev,
 147                 struct device_attribute *attr, const char *buf, size_t count)
 148 {
 149         int rc;
 150         struct backlight_device *bd = to_backlight_device(dev);
 151         unsigned long brightness;
 152
 153         rc = strict_strtoul(buf, 0, &brightness);
 154         if (rc)
 155                 return rc;
 156
 157         rc = -ENXIO;
 158
 159         mutex_lock(&bd->ops_lock);
 160         if (bd->ops) {
 161                 if (brightness > bd->props.max_brightness)
 162                         rc = -EINVAL;
 163                 else {
 164                         pr_debug("backlight: set brightness to %lu\n",
 165                                  brightness);
 166                         bd->props.brightness = brightness;
 167                         backlight_update_status(bd);
 168                         rc = count;
 169                 }
 170         }
 171         mutex_unlock(&bd->ops_lock);
 172
 173         backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
 174
 175         return rc;
 176 }
 177
 178 static ssize_t backlight_show_type(struct device *dev,
 179                 struct device_attribute *attr, char *buf)
 180 {
 181         struct backlight_device *bd = to_backlight_device(dev);
 182
 183         return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
 184 }
 185
 186 static ssize_t backlight_show_max_brightness(struct device *dev,
 187                 struct device_attribute *attr, char *buf)
 188 {
 189         struct backlight_device *bd = to_backlight_device(dev);
 190
 191         return sprintf(buf, "%d\n", bd->props.max_brightness);
 192 }
 193
 194 static ssize_t backlight_show_actual_brightness(struct device *dev,
 195                 struct device_attribute *attr, char *buf)
 196 {
 197         int rc = -ENXIO;
 198         struct backlight_device *bd = to_backlight_device(dev);
 199
 200         mutex_lock(&bd->ops_lock);
 201         if (bd->ops && bd->ops->get_brightness)
 202                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 203         mutex_unlock(&bd->ops_lock);
 204
 205         return rc;
 206 }
 207
 208 static struct class *backlight_class;
 209
 210 static int backlight_suspend(struct device *dev, pm_message_t state)
 211 {
 212         struct backlight_device *bd = to_backlight_device(dev);
 213
 214         mutex_lock(&bd->ops_lock);
 215         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 216                 bd->props.state |= BL_CORE_SUSPENDED;
 217                 backlight_update_status(bd);
 218         }
 219         mutex_unlock(&bd->ops_lock);
 220
 221         return 0;
 222 }
 223
 224 static int backlight_resume(struct device *dev)
 225 {
 226         struct backlight_device *bd = to_backlight_device(dev);
 227
 228         mutex_lock(&bd->ops_lock);
 229         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 230                 bd->props.state &= ~BL_CORE_SUSPENDED;
 231                 backlight_update_status(bd);
 232         }
 233         mutex_unlock(&bd->ops_lock);
 234
 235         return 0;
 236 }
 237
 238 static void bl_device_release(struct device *dev)
 239 {
 240         struct backlight_device *bd = to_backlight_device(dev);
 241         kfree(bd);
 242 }
 243
 244 static struct device_attribute bl_device_attributes[] = {
 245         __ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
 246         __ATTR(brightness, 0644, backlight_show_brightness,
 247                      backlight_store_brightness),
 248         __ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 249                      NULL),
 250         __ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 251         __ATTR(type, 0444, backlight_show_type, NULL),
 252         __ATTR_NULL,
 253 };
 254
 255 /**
 256  * backlight_force_update - tell the backlight subsystem that hardware state
 257  *   has changed
 258  * @bd: the backlight device to update
 259  *
 260  * Updates the internal state of the backlight in response to a hardware event,
 261  * and generate a uevent to notify userspace
 262  */
 263 void backlight_force_update(struct backlight_device *bd,
 264                             enum backlight_update_reason reason)
 265 {
 266         mutex_lock(&bd->ops_lock);
 267         if (bd->ops && bd->ops->get_brightness)
 268                 bd->props.brightness = bd->ops->get_brightness(bd);
 269         mutex_unlock(&bd->ops_lock);
 270         backlight_generate_event(bd, reason);
 271 }
 272 EXPORT_SYMBOL(backlight_force_update);
 273
 274 /**
 275  * backlight_device_register - create and register a new object of
 276  *   backlight_device class.
 277  * @name: the name of the new object(must be the same as the name of the
 278  *   respective framebuffer device).
 279  * @parent: a pointer to the parent device
 280  * @devdata: an optional pointer to be stored for private driver use. The
 281  *   methods may retrieve it by using bl_get_data(bd).
 282  * @ops: the backlight operations structure.
 283  *
 284  * Creates and registers new backlight device. Returns either an
 285  * ERR_PTR() or a pointer to the newly allocated device.
 286  */
 287 struct backlight_device *backlight_device_register(const char *name,
 288         struct device *parent, void *devdata, const struct backlight_ops *ops,
 289         const struct backlight_properties *props)
 290 {
 291         struct backlight_device *new_bd;
 292         int rc;
 293
 294         pr_debug("backlight_device_register: name=%s\n", name);
 295
 296         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 297         if (!new_bd)
 298                 return ERR_PTR(-ENOMEM);
 299
 300         mutex_init(&new_bd->update_lock);
 301         mutex_init(&new_bd->ops_lock);
 302
 303         new_bd->dev.class = backlight_class;
 304         new_bd->dev.parent = parent;
 305         new_bd->dev.release = bl_device_release;
 306         dev_set_name(&new_bd->dev, name);
 307         dev_set_drvdata(&new_bd->dev, devdata);
 308
 309         /* Set default properties */
 310         if (props) {
 311                 memcpy(&new_bd->props, props,
 312                        sizeof(struct backlight_properties));
 313                 if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
 314                         WARN(1, "%s: invalid backlight type", name);
 315                         new_bd->props.type = BACKLIGHT_RAW;
 316                 }
 317         } else {
 318                 new_bd->props.type = BACKLIGHT_RAW;
 319         }
 320
 321         rc = device_register(&new_bd->dev);
 322         if (rc) {
 323                 kfree(new_bd);
 324                 return ERR_PTR(rc);
 325         }
 326
 327         rc = backlight_register_fb(new_bd);
 328         if (rc) {
 329                 device_unregister(&new_bd->dev);
 330                 return ERR_PTR(rc);
 331         }
 332
 333         new_bd->ops = ops;
 334
 335 #ifdef CONFIG_PMAC_BACKLIGHT
 336         mutex_lock(&pmac_backlight_mutex);
 337         if (!pmac_backlight)
 338                 pmac_backlight = new_bd;
 339         mutex_unlock(&pmac_backlight_mutex);
 340 #endif
 341
 342         return new_bd;
 343 }
 344 EXPORT_SYMBOL(backlight_device_register);
 345
 346 /**
 347  * backlight_device_unregister - unregisters a backlight device object.
 348  * @bd: the backlight device object to be unregistered and freed.
 349  *
 350  * Unregisters a previously registered via backlight_device_register object.
 351  */
 352 void backlight_device_unregister(struct backlight_device *bd)
 353 {
 354         if (!bd)
 355                 return;
 356
 357 #ifdef CONFIG_PMAC_BACKLIGHT
 358         mutex_lock(&pmac_backlight_mutex);
 359         if (pmac_backlight == bd)
 360                 pmac_backlight = NULL;
 361         mutex_unlock(&pmac_backlight_mutex);
 362 #endif
 363         mutex_lock(&bd->ops_lock);
 364         bd->ops = NULL;
 365         mutex_unlock(&bd->ops_lock);
 366
 367         backlight_unregister_fb(bd);
 368         device_unregister(&bd->dev);
 369 }
 370 EXPORT_SYMBOL(backlight_device_unregister);
 371
 372 static void __exit backlight_class_exit(void)
 373 {
 374         class_destroy(backlight_class);
 375 }
 376
 377 static int __init backlight_class_init(void)
 378 {
 379         backlight_class = class_create(THIS_MODULE, "backlight");
 380         if (IS_ERR(backlight_class)) {
 381                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 382                                 PTR_ERR(backlight_class));
 383                 return PTR_ERR(backlight_class);
 384         }
 385
 386         backlight_class->dev_attrs = bl_device_attributes;
 387         backlight_class->suspend = backlight_suspend;
 388         backlight_class->resume = backlight_resume;
 389         return 0;
 390 }
 391
 392 /*
 393  * if this is compiled into the kernel, we need to ensure that the
 394  * class is registered before users of the class try to register lcd's
 395  */
 396 postcore_initcall(backlight_class_init);
 397 module_exit(backlight_class_exit);
 398
 399 MODULE_LICENSE("GPL");
 400 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 401 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");