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