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