drivers/video/backlight/backlight.c

   1 /*
   2  * Backlight Lowlevel Control Abstraction
   3  *
   4  * Copyright (C) 2003,2004 Hewlett-Packard Company
   5  *
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/backlight.h>
  14 #include <linux/notifier.h>
  15 #include <linux/ctype.h>
  16 #include <linux/err.h>
  17 #include <linux/fb.h>
  18 #include <linux/slab.h>
  19
  20 #ifdef CONFIG_PMAC_BACKLIGHT
  21 #include <asm/backlight.h>
  22 #endif
  23
  24 static const char *const backlight_types[] = {
  25         [BACKLIGHT_RAW] = "raw",
  26         [BACKLIGHT_PLATFORM] = "platform",
  27         [BACKLIGHT_FIRMWARE] = "firmware",
  28 };
  29
  30 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
  31                            defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
  32 /* This callback gets called when something important happens inside a
  33  * framebuffer driver. We're looking if that important event is blanking,
  34  * and if it is, we're switching backlight power as well ...
  35  */
  36 static int fb_notifier_callback(struct notifier_block *self,
  37                                 unsigned long event, void *data)
  38 {
  39         struct backlight_device *bd;
  40         struct fb_event *evdata = data;
  41
  42         /* If we aren't interested in this event, skip it immediately ... */
  43         if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
  44                 return 0;
  45
  46         bd = container_of(self, struct backlight_device, fb_notif);
  47         mutex_lock(&bd->ops_lock);
  48         if (bd->ops)
  49                 if (!bd->ops->check_fb ||
  50                     bd->ops->check_fb(bd, evdata->info)) {
  51                         bd->props.fb_blank = *(int *)evdata->data;
  52                         if (bd->props.fb_blank == FB_BLANK_UNBLANK)
  53                                 bd->props.state &= ~BL_CORE_FBBLANK;
  54                         else
  55                                 bd->props.state |= BL_CORE_FBBLANK;
  56                         backlight_update_status(bd);
  57                 }
  58         mutex_unlock(&bd->ops_lock);
  59         return 0;
  60 }
  61
  62 static int backlight_register_fb(struct backlight_device *bd)
  63 {
  64         memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
  65         bd->fb_notif.notifier_call = fb_notifier_callback;
  66
  67         return fb_register_client(&bd->fb_notif);
  68 }
  69
  70 static void backlight_unregister_fb(struct backlight_device *bd)
  71 {
  72         fb_unregister_client(&bd->fb_notif);
  73 }
  74 #else
  75 static inline int backlight_register_fb(struct backlight_device *bd)
  76 {
  77         return 0;
  78 }
  79
  80 static inline void backlight_unregister_fb(struct backlight_device *bd)
  81 {
  82 }
  83 #endif /* CONFIG_FB */
  84
  85 static void backlight_generate_event(struct backlight_device *bd,
  86                                      enum backlight_update_reason reason)
  87 {
  88         char *envp[2];
  89
  90         switch (reason) {
  91         case BACKLIGHT_UPDATE_SYSFS:
  92                 envp[0] = "SOURCE=sysfs";
  93                 break;
  94         case BACKLIGHT_UPDATE_HOTKEY:
  95                 envp[0] = "SOURCE=hotkey";
  96                 break;
  97         default:
  98                 envp[0] = "SOURCE=unknown";
  99                 break;
 100         }
 101         envp[1] = NULL;
 102         kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
 103         sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
 104 }
 105
 106 static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
 107                 char *buf)
 108 {
 109         struct backlight_device *bd = to_backlight_device(dev);
 110
 111         return sprintf(buf, "%d\n", bd->props.power);
 112 }
 113
 114 static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
 115                 const char *buf, size_t count)
 116 {
 117         int rc;
 118         struct backlight_device *bd = to_backlight_device(dev);
 119         unsigned long power;
 120
 121         rc = kstrtoul(buf, 0, &power);
 122         if (rc)
 123                 return rc;
 124
 125         rc = -ENXIO;
 126         mutex_lock(&bd->ops_lock);
 127         if (bd->ops) {
 128                 pr_debug("set power to %lu\n", power);
 129                 if (bd->props.power != power) {
 130                         bd->props.power = power;
 131                         backlight_update_status(bd);
 132                 }
 133                 rc = count;
 134         }
 135         mutex_unlock(&bd->ops_lock);
 136
 137         return rc;
 138 }
 139 static DEVICE_ATTR_RW(bl_power);
 140
 141 static ssize_t brightness_show(struct device *dev,
 142                 struct device_attribute *attr, char *buf)
 143 {
 144         struct backlight_device *bd = to_backlight_device(dev);
 145
 146         return sprintf(buf, "%d\n", bd->props.brightness);
 147 }
 148
 149 static ssize_t brightness_store(struct device *dev,
 150                 struct device_attribute *attr, const char *buf, size_t count)
 151 {
 152         int rc;
 153         struct backlight_device *bd = to_backlight_device(dev);
 154         unsigned long brightness;
 155
 156         rc = kstrtoul(buf, 0, &brightness);
 157         if (rc)
 158                 return rc;
 159
 160         rc = -ENXIO;
 161
 162         mutex_lock(&bd->ops_lock);
 163         if (bd->ops) {
 164                 if (brightness > bd->props.max_brightness)
 165                         rc = -EINVAL;
 166                 else {
 167                         pr_debug("set brightness to %lu\n", brightness);
 168                         bd->props.brightness = brightness;
 169                         backlight_update_status(bd);
 170                         rc = count;
 171                 }
 172         }
 173         mutex_unlock(&bd->ops_lock);
 174
 175         backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
 176
 177         return rc;
 178 }
 179 static DEVICE_ATTR_RW(brightness);
 180
 181 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
 182                 char *buf)
 183 {
 184         struct backlight_device *bd = to_backlight_device(dev);
 185
 186         return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
 187 }
 188 static DEVICE_ATTR_RO(type);
 189
 190 static ssize_t max_brightness_show(struct device *dev,
 191                 struct device_attribute *attr, char *buf)
 192 {
 193         struct backlight_device *bd = to_backlight_device(dev);
 194
 195         return sprintf(buf, "%d\n", bd->props.max_brightness);
 196 }
 197 static DEVICE_ATTR_RO(max_brightness);
 198
 199 static ssize_t actual_brightness_show(struct device *dev,
 200                 struct device_attribute *attr, char *buf)
 201 {
 202         int rc = -ENXIO;
 203         struct backlight_device *bd = to_backlight_device(dev);
 204
 205         mutex_lock(&bd->ops_lock);
 206         if (bd->ops && bd->ops->get_brightness)
 207                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 208         mutex_unlock(&bd->ops_lock);
 209
 210         return rc;
 211 }
 212 static DEVICE_ATTR_RO(actual_brightness);
 213
 214 static struct class *backlight_class;
 215
 216 #ifdef CONFIG_PM_SLEEP
 217 static int backlight_suspend(struct device *dev)
 218 {
 219         struct backlight_device *bd = to_backlight_device(dev);
 220
 221         mutex_lock(&bd->ops_lock);
 222         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 223                 bd->props.state |= BL_CORE_SUSPENDED;
 224                 backlight_update_status(bd);
 225         }
 226         mutex_unlock(&bd->ops_lock);
 227
 228         return 0;
 229 }
 230
 231 static int backlight_resume(struct device *dev)
 232 {
 233         struct backlight_device *bd = to_backlight_device(dev);
 234
 235         mutex_lock(&bd->ops_lock);
 236         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 237                 bd->props.state &= ~BL_CORE_SUSPENDED;
 238                 backlight_update_status(bd);
 239         }
 240         mutex_unlock(&bd->ops_lock);
 241
 242         return 0;
 243 }
 244 #endif
 245
 246 static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
 247                          backlight_resume);
 248
 249 static void bl_device_release(struct device *dev)
 250 {
 251         struct backlight_device *bd = to_backlight_device(dev);
 252         kfree(bd);
 253 }
 254
 255 static struct attribute *bl_device_attrs[] = {
 256         &dev_attr_bl_power.attr,
 257         &dev_attr_brightness.attr,
 258         &dev_attr_actual_brightness.attr,
 259         &dev_attr_max_brightness.attr,
 260         &dev_attr_type.attr,
 261         NULL,
 262 };
 263 ATTRIBUTE_GROUPS(bl_device);
 264
 265 /**
 266  * backlight_force_update - tell the backlight subsystem that hardware state
 267  *   has changed
 268  * @bd: the backlight device to update
 269  *
 270  * Updates the internal state of the backlight in response to a hardware event,
 271  * and generate a uevent to notify userspace
 272  */
 273 void backlight_force_update(struct backlight_device *bd,
 274                             enum backlight_update_reason reason)
 275 {
 276         mutex_lock(&bd->ops_lock);
 277         if (bd->ops && bd->ops->get_brightness)
 278                 bd->props.brightness = bd->ops->get_brightness(bd);
 279         mutex_unlock(&bd->ops_lock);
 280         backlight_generate_event(bd, reason);
 281 }
 282 EXPORT_SYMBOL(backlight_force_update);
 283
 284 /**
 285  * backlight_device_register - create and register a new object of
 286  *   backlight_device class.
 287  * @name: the name of the new object(must be the same as the name of the
 288  *   respective framebuffer device).
 289  * @parent: a pointer to the parent device
 290  * @devdata: an optional pointer to be stored for private driver use. The
 291  *   methods may retrieve it by using bl_get_data(bd).
 292  * @ops: the backlight operations structure.
 293  *
 294  * Creates and registers new backlight device. Returns either an
 295  * ERR_PTR() or a pointer to the newly allocated device.
 296  */
 297 struct backlight_device *backlight_device_register(const char *name,
 298         struct device *parent, void *devdata, const struct backlight_ops *ops,
 299         const struct backlight_properties *props)
 300 {
 301         struct backlight_device *new_bd;
 302         int rc;
 303
 304         pr_debug("backlight_device_register: name=%s\n", name);
 305
 306         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 307         if (!new_bd)
 308                 return ERR_PTR(-ENOMEM);
 309
 310         mutex_init(&new_bd->update_lock);
 311         mutex_init(&new_bd->ops_lock);
 312
 313         new_bd->dev.class = backlight_class;
 314         new_bd->dev.parent = parent;
 315         new_bd->dev.release = bl_device_release;
 316         dev_set_name(&new_bd->dev, "%s", name);
 317         dev_set_drvdata(&new_bd->dev, devdata);
 318
 319         /* Set default properties */
 320         if (props) {
 321                 memcpy(&new_bd->props, props,
 322                        sizeof(struct backlight_properties));
 323                 if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
 324                         WARN(1, "%s: invalid backlight type", name);
 325                         new_bd->props.type = BACKLIGHT_RAW;
 326                 }
 327         } else {
 328                 new_bd->props.type = BACKLIGHT_RAW;
 329         }
 330
 331         rc = device_register(&new_bd->dev);
 332         if (rc) {
 333                 kfree(new_bd);
 334                 return ERR_PTR(rc);
 335         }
 336
 337         rc = backlight_register_fb(new_bd);
 338         if (rc) {
 339                 device_unregister(&new_bd->dev);
 340                 return ERR_PTR(rc);
 341         }
 342
 343         new_bd->ops = ops;
 344
 345 #ifdef CONFIG_PMAC_BACKLIGHT
 346         mutex_lock(&pmac_backlight_mutex);
 347         if (!pmac_backlight)
 348                 pmac_backlight = new_bd;
 349         mutex_unlock(&pmac_backlight_mutex);
 350 #endif
 351
 352         return new_bd;
 353 }
 354 EXPORT_SYMBOL(backlight_device_register);
 355
 356 /**
 357  * backlight_device_unregister - unregisters a backlight device object.
 358  * @bd: the backlight device object to be unregistered and freed.
 359  *
 360  * Unregisters a previously registered via backlight_device_register object.
 361  */
 362 void backlight_device_unregister(struct backlight_device *bd)
 363 {
 364         if (!bd)
 365                 return;
 366
 367 #ifdef CONFIG_PMAC_BACKLIGHT
 368         mutex_lock(&pmac_backlight_mutex);
 369         if (pmac_backlight == bd)
 370                 pmac_backlight = NULL;
 371         mutex_unlock(&pmac_backlight_mutex);
 372 #endif
 373         mutex_lock(&bd->ops_lock);
 374         bd->ops = NULL;
 375         mutex_unlock(&bd->ops_lock);
 376
 377         backlight_unregister_fb(bd);
 378         device_unregister(&bd->dev);
 379 }
 380 EXPORT_SYMBOL(backlight_device_unregister);
 381
 382 static void devm_backlight_device_release(struct device *dev, void *res)
 383 {
 384         struct backlight_device *backlight = *(struct backlight_device **)res;
 385
 386         backlight_device_unregister(backlight);
 387 }
 388
 389 static int devm_backlight_device_match(struct device *dev, void *res,
 390                                         void *data)
 391 {
 392         struct backlight_device **r = res;
 393
 394         return *r == data;
 395 }
 396
 397 /**
 398  * devm_backlight_device_register - resource managed backlight_device_register()
 399  * @dev: the device to register
 400  * @name: the name of the device
 401  * @parent: a pointer to the parent device
 402  * @devdata: an optional pointer to be stored for private driver use
 403  * @ops: the backlight operations structure
 404  * @props: the backlight properties
 405  *
 406  * @return a struct backlight on success, or an ERR_PTR on error
 407  *
 408  * Managed backlight_device_register(). The backlight_device returned
 409  * from this function are automatically freed on driver detach.
 410  * See backlight_device_register() for more information.
 411  */
 412 struct backlight_device *devm_backlight_device_register(struct device *dev,
 413         const char *name, struct device *parent, void *devdata,
 414         const struct backlight_ops *ops,
 415         const struct backlight_properties *props)
 416 {
 417         struct backlight_device **ptr, *backlight;
 418
 419         ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
 420                         GFP_KERNEL);
 421         if (!ptr)
 422                 return ERR_PTR(-ENOMEM);
 423
 424         backlight = backlight_device_register(name, parent, devdata, ops,
 425                                                 props);
 426         if (!IS_ERR(backlight)) {
 427                 *ptr = backlight;
 428                 devres_add(dev, ptr);
 429         } else {
 430                 devres_free(ptr);
 431         }
 432
 433         return backlight;
 434 }
 435 EXPORT_SYMBOL(devm_backlight_device_register);
 436
 437 /**
 438  * devm_backlight_device_unregister - resource managed backlight_device_unregister()
 439  * @dev: the device to unregister
 440  * @bd: the backlight device to unregister
 441  *
 442  * Deallocated a backlight allocated with devm_backlight_device_register().
 443  * Normally this function will not need to be called and the resource management
 444  * code will ensure that the resource is freed.
 445  */
 446 void devm_backlight_device_unregister(struct device *dev,
 447                                 struct backlight_device *bd)
 448 {
 449         int rc;
 450
 451         rc = devres_release(dev, devm_backlight_device_release,
 452                                 devm_backlight_device_match, bd);
 453         WARN_ON(rc);
 454 }
 455 EXPORT_SYMBOL(devm_backlight_device_unregister);
 456
 457 #ifdef CONFIG_OF
 458 static int of_parent_match(struct device *dev, const void *data)
 459 {
 460         return dev->parent && dev->parent->of_node == data;
 461 }
 462
 463 /**
 464  * of_find_backlight_by_node() - find backlight device by device-tree node
 465  * @node: device-tree node of the backlight device
 466  *
 467  * Returns a pointer to the backlight device corresponding to the given DT
 468  * node or NULL if no such backlight device exists or if the device hasn't
 469  * been probed yet.
 470  *
 471  * This function obtains a reference on the backlight device and it is the
 472  * caller's responsibility to drop the reference by calling put_device() on
 473  * the backlight device's .dev field.
 474  */
 475 struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 476 {
 477         struct device *dev;
 478
 479         dev = class_find_device(backlight_class, NULL, node, of_parent_match);
 480
 481         return dev ? to_backlight_device(dev) : NULL;
 482 }
 483 EXPORT_SYMBOL(of_find_backlight_by_node);
 484 #endif
 485
 486 static void __exit backlight_class_exit(void)
 487 {
 488         class_destroy(backlight_class);
 489 }
 490
 491 static int __init backlight_class_init(void)
 492 {
 493         backlight_class = class_create(THIS_MODULE, "backlight");
 494         if (IS_ERR(backlight_class)) {
 495                 pr_warn("Unable to create backlight class; errno = %ld\n",
 496                         PTR_ERR(backlight_class));
 497                 return PTR_ERR(backlight_class);
 498         }
 499
 500         backlight_class->dev_groups = bl_device_groups;
 501         backlight_class->pm = &backlight_class_dev_pm_ops;
 502         return 0;
 503 }
 504
 505 /*
 506  * if this is compiled into the kernel, we need to ensure that the
 507  * class is registered before users of the class try to register lcd's
 508  */
 509 postcore_initcall(backlight_class_init);
 510 module_exit(backlight_class_exit);
 511
 512 MODULE_LICENSE("GPL");
 513 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 514 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");