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, 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, 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"); 432