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 backlight_show_power(struct device *dev,
 107                 struct device_attribute *attr, 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 backlight_store_power(struct device *dev,
 115                 struct device_attribute *attr, 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
 140 static ssize_t backlight_show_brightness(struct device *dev,
 141                 struct device_attribute *attr, char *buf)
 142 {
 143         struct backlight_device *bd = to_backlight_device(dev);
 144
 145         return sprintf(buf, "%d\n", bd->props.brightness);
 146 }
 147
 148 static ssize_t backlight_store_brightness(struct device *dev,
 149                 struct device_attribute *attr, const char *buf, size_t count)
 150 {
 151         int rc;
 152         struct backlight_device *bd = to_backlight_device(dev);
 153         unsigned long brightness;
 154
 155         rc = kstrtoul(buf, 0, &brightness);
 156         if (rc)
 157                 return rc;
 158
 159         rc = -ENXIO;
 160
 161         mutex_lock(&bd->ops_lock);
 162         if (bd->ops) {
 163                 if (brightness > bd->props.max_brightness)
 164                         rc = -EINVAL;
 165                 else {
 166                         pr_debug("set brightness to %lu\n", brightness);
 167                         bd->props.brightness = brightness;
 168                         backlight_update_status(bd);
 169                         rc = count;
 170                 }
 171         }
 172         mutex_unlock(&bd->ops_lock);
 173
 174         backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
 175
 176         return rc;
 177 }
 178
 179 static ssize_t backlight_show_type(struct device *dev,
 180                 struct device_attribute *attr, char *buf)
 181 {
 182         struct backlight_device *bd = to_backlight_device(dev);
 183
 184         return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
 185 }
 186
 187 static ssize_t backlight_show_max_brightness(struct device *dev,
 188                 struct device_attribute *attr, char *buf)
 189 {
 190         struct backlight_device *bd = to_backlight_device(dev);
 191
 192         return sprintf(buf, "%d\n", bd->props.max_brightness);
 193 }
 194
 195 static ssize_t backlight_show_actual_brightness(struct device *dev,
 196                 struct device_attribute *attr, char *buf)
 197 {
 198         int rc = -ENXIO;
 199         struct backlight_device *bd = to_backlight_device(dev);
 200
 201         mutex_lock(&bd->ops_lock);
 202         if (bd->ops && bd->ops->get_brightness)
 203                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 204         mutex_unlock(&bd->ops_lock);
 205
 206         return rc;
 207 }
 208
 209 static struct class *backlight_class;
 210
 211 static int backlight_suspend(struct device *dev, pm_message_t state)
 212 {
 213         struct backlight_device *bd = to_backlight_device(dev);
 214
 215         mutex_lock(&bd->ops_lock);
 216         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 217                 bd->props.state |= BL_CORE_SUSPENDED;
 218                 backlight_update_status(bd);
 219         }
 220         mutex_unlock(&bd->ops_lock);
 221
 222         return 0;
 223 }
 224
 225 static int backlight_resume(struct device *dev)
 226 {
 227         struct backlight_device *bd = to_backlight_device(dev);
 228
 229         mutex_lock(&bd->ops_lock);
 230         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 231                 bd->props.state &= ~BL_CORE_SUSPENDED;
 232                 backlight_update_status(bd);
 233         }
 234         mutex_unlock(&bd->ops_lock);
 235
 236         return 0;
 237 }
 238
 239 static void bl_device_release(struct device *dev)
 240 {
 241         struct backlight_device *bd = to_backlight_device(dev);
 242         kfree(bd);
 243 }
 244
 245 static struct device_attribute bl_device_attributes[] = {
 246         __ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
 247         __ATTR(brightness, 0644, backlight_show_brightness,
 248                      backlight_store_brightness),
 249         __ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 250                      NULL),
 251         __ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 252         __ATTR(type, 0444, backlight_show_type, NULL),
 253         __ATTR_NULL,
 254 };
 255
 256 /**
 257  * backlight_force_update - tell the backlight subsystem that hardware state
 258  *   has changed
 259  * @bd: the backlight device to update
 260  *
 261  * Updates the internal state of the backlight in response to a hardware event,
 262  * and generate a uevent to notify userspace
 263  */
 264 void backlight_force_update(struct backlight_device *bd,
 265                             enum backlight_update_reason reason)
 266 {
 267         mutex_lock(&bd->ops_lock);
 268         if (bd->ops && bd->ops->get_brightness)
 269                 bd->props.brightness = bd->ops->get_brightness(bd);
 270         mutex_unlock(&bd->ops_lock);
 271         backlight_generate_event(bd, reason);
 272 }
 273 EXPORT_SYMBOL(backlight_force_update);
 274
 275 /**
 276  * backlight_device_register - create and register a new object of
 277  *   backlight_device class.
 278  * @name: the name of the new object(must be the same as the name of the
 279  *   respective framebuffer device).
 280  * @parent: a pointer to the parent device
 281  * @devdata: an optional pointer to be stored for private driver use. The
 282  *   methods may retrieve it by using bl_get_data(bd).
 283  * @ops: the backlight operations structure.
 284  *
 285  * Creates and registers new backlight device. Returns either an
 286  * ERR_PTR() or a pointer to the newly allocated device.
 287  */
 288 struct backlight_device *backlight_device_register(const char *name,
 289         struct device *parent, void *devdata, const struct backlight_ops *ops,
 290         const struct backlight_properties *props)
 291 {
 292         struct backlight_device *new_bd;
 293         int rc;
 294
 295         pr_debug("backlight_device_register: name=%s\n", name);
 296
 297         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 298         if (!new_bd)
 299                 return ERR_PTR(-ENOMEM);
 300
 301         mutex_init(&new_bd->update_lock);
 302         mutex_init(&new_bd->ops_lock);
 303
 304         new_bd->dev.class = backlight_class;
 305         new_bd->dev.parent = parent;
 306         new_bd->dev.release = bl_device_release;
 307         dev_set_name(&new_bd->dev, "%s", name);
 308         dev_set_drvdata(&new_bd->dev, devdata);
 309
 310         /* Set default properties */
 311         if (props) {
 312                 memcpy(&new_bd->props, props,
 313                        sizeof(struct backlight_properties));
 314                 if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
 315                         WARN(1, "%s: invalid backlight type", name);
 316                         new_bd->props.type = BACKLIGHT_RAW;
 317                 }
 318         } else {
 319                 new_bd->props.type = BACKLIGHT_RAW;
 320         }
 321
 322         rc = device_register(&new_bd->dev);
 323         if (rc) {
 324                 kfree(new_bd);
 325                 return ERR_PTR(rc);
 326         }
 327
 328         rc = backlight_register_fb(new_bd);
 329         if (rc) {
 330                 device_unregister(&new_bd->dev);
 331                 return ERR_PTR(rc);
 332         }
 333
 334         new_bd->ops = ops;
 335
 336 #ifdef CONFIG_PMAC_BACKLIGHT
 337         mutex_lock(&pmac_backlight_mutex);
 338         if (!pmac_backlight)
 339                 pmac_backlight = new_bd;
 340         mutex_unlock(&pmac_backlight_mutex);
 341 #endif
 342
 343         return new_bd;
 344 }
 345 EXPORT_SYMBOL(backlight_device_register);
 346
 347 /**
 348  * backlight_device_unregister - unregisters a backlight device object.
 349  * @bd: the backlight device object to be unregistered and freed.
 350  *
 351  * Unregisters a previously registered via backlight_device_register object.
 352  */
 353 void backlight_device_unregister(struct backlight_device *bd)
 354 {
 355         if (!bd)
 356                 return;
 357
 358 #ifdef CONFIG_PMAC_BACKLIGHT
 359         mutex_lock(&pmac_backlight_mutex);
 360         if (pmac_backlight == bd)
 361                 pmac_backlight = NULL;
 362         mutex_unlock(&pmac_backlight_mutex);
 363 #endif
 364         mutex_lock(&bd->ops_lock);
 365         bd->ops = NULL;
 366         mutex_unlock(&bd->ops_lock);
 367
 368         backlight_unregister_fb(bd);
 369         device_unregister(&bd->dev);
 370 }
 371 EXPORT_SYMBOL(backlight_device_unregister);
 372
 373 #ifdef CONFIG_OF
 374 static int of_parent_match(struct device *dev, const void *data)
 375 {
 376         return dev->parent && dev->parent->of_node == data;
 377 }
 378
 379 /**
 380  * of_find_backlight_by_node() - find backlight device by device-tree node
 381  * @node: device-tree node of the backlight device
 382  *
 383  * Returns a pointer to the backlight device corresponding to the given DT
 384  * node or NULL if no such backlight device exists or if the device hasn't
 385  * been probed yet.
 386  *
 387  * This function obtains a reference on the backlight device and it is the
 388  * caller's responsibility to drop the reference by calling put_device() on
 389  * the backlight device's .dev field.
 390  */
 391 struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 392 {
 393         struct device *dev;
 394
 395         dev = class_find_device(backlight_class, NULL, node, of_parent_match);
 396
 397         return dev ? to_backlight_device(dev) : NULL;
 398 }
 399 EXPORT_SYMBOL(of_find_backlight_by_node);
 400 #endif
 401
 402 static void __exit backlight_class_exit(void)
 403 {
 404         class_destroy(backlight_class);
 405 }
 406
 407 static int __init backlight_class_init(void)
 408 {
 409         backlight_class = class_create(THIS_MODULE, "backlight");
 410         if (IS_ERR(backlight_class)) {
 411                 pr_warn("Unable to create backlight class; errno = %ld\n",
 412                         PTR_ERR(backlight_class));
 413                 return PTR_ERR(backlight_class);
 414         }
 415
 416         backlight_class->dev_attrs = bl_device_attributes;
 417         backlight_class->suspend = backlight_suspend;
 418         backlight_class->resume = backlight_resume;
 419         return 0;
 420 }
 421
 422 /*
 423  * if this is compiled into the kernel, we need to ensure that the
 424  * class is registered before users of the class try to register lcd's
 425  */
 426 postcore_initcall(backlight_class_init);
 427 module_exit(backlight_class_exit);
 428
 429 MODULE_LICENSE("GPL");
 430 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 431 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");