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         sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
  95 }
  96
  97 static ssize_t backlight_show_power(struct device *dev,
  98                 struct device_attribute *attr,char *buf)
  99 {
 100         struct backlight_device *bd = to_backlight_device(dev);
 101
 102         return sprintf(buf, "%d\n", bd->props.power);
 103 }
 104
 105 static ssize_t backlight_store_power(struct device *dev,
 106                 struct device_attribute *attr, const char *buf, size_t count)
 107 {
 108         int rc;
 109         struct backlight_device *bd = to_backlight_device(dev);
 110         unsigned long power;
 111
 112         rc = strict_strtoul(buf, 0, &power);
 113         if (rc)
 114                 return rc;
 115
 116         rc = -ENXIO;
 117         mutex_lock(&bd->ops_lock);
 118         if (bd->ops) {
 119                 pr_debug("backlight: set power to %lu\n", power);
 120                 if (bd->props.power != power) {
 121                         bd->props.power = power;
 122                         backlight_update_status(bd);
 123                 }
 124                 rc = count;
 125         }
 126         mutex_unlock(&bd->ops_lock);
 127
 128         return rc;
 129 }
 130
 131 static ssize_t backlight_show_brightness(struct device *dev,
 132                 struct device_attribute *attr, char *buf)
 133 {
 134         struct backlight_device *bd = to_backlight_device(dev);
 135
 136         return sprintf(buf, "%d\n", bd->props.brightness);
 137 }
 138
 139 static ssize_t backlight_store_brightness(struct device *dev,
 140                 struct device_attribute *attr, const char *buf, size_t count)
 141 {
 142         int rc;
 143         struct backlight_device *bd = to_backlight_device(dev);
 144         unsigned long brightness;
 145
 146         rc = strict_strtoul(buf, 0, &brightness);
 147         if (rc)
 148                 return rc;
 149
 150         rc = -ENXIO;
 151
 152         mutex_lock(&bd->ops_lock);
 153         if (bd->ops) {
 154                 if (brightness > bd->props.max_brightness)
 155                         rc = -EINVAL;
 156                 else {
 157                         pr_debug("backlight: set brightness to %lu\n",
 158                                  brightness);
 159                         bd->props.brightness = brightness;
 160                         backlight_update_status(bd);
 161                         rc = count;
 162                 }
 163         }
 164         mutex_unlock(&bd->ops_lock);
 165
 166         backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
 167
 168         return rc;
 169 }
 170
 171 static ssize_t backlight_show_max_brightness(struct device *dev,
 172                 struct device_attribute *attr, char *buf)
 173 {
 174         struct backlight_device *bd = to_backlight_device(dev);
 175
 176         return sprintf(buf, "%d\n", bd->props.max_brightness);
 177 }
 178
 179 static ssize_t backlight_show_actual_brightness(struct device *dev,
 180                 struct device_attribute *attr, char *buf)
 181 {
 182         int rc = -ENXIO;
 183         struct backlight_device *bd = to_backlight_device(dev);
 184
 185         mutex_lock(&bd->ops_lock);
 186         if (bd->ops && bd->ops->get_brightness)
 187                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 188         mutex_unlock(&bd->ops_lock);
 189
 190         return rc;
 191 }
 192
 193 static struct class *backlight_class;
 194
 195 static int backlight_suspend(struct device *dev, pm_message_t state)
 196 {
 197         struct backlight_device *bd = to_backlight_device(dev);
 198
 199         mutex_lock(&bd->ops_lock);
 200         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 201                 bd->props.state |= BL_CORE_SUSPENDED;
 202                 backlight_update_status(bd);
 203         }
 204         mutex_unlock(&bd->ops_lock);
 205
 206         return 0;
 207 }
 208
 209 static int backlight_resume(struct device *dev)
 210 {
 211         struct backlight_device *bd = to_backlight_device(dev);
 212
 213         mutex_lock(&bd->ops_lock);
 214         if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 215                 bd->props.state &= ~BL_CORE_SUSPENDED;
 216                 backlight_update_status(bd);
 217         }
 218         mutex_unlock(&bd->ops_lock);
 219
 220         return 0;
 221 }
 222
 223 static void bl_device_release(struct device *dev)
 224 {
 225         struct backlight_device *bd = to_backlight_device(dev);
 226         kfree(bd);
 227 }
 228
 229 static struct device_attribute bl_device_attributes[] = {
 230         __ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
 231         __ATTR(brightness, 0644, backlight_show_brightness,
 232                      backlight_store_brightness),
 233         __ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 234                      NULL),
 235         __ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 236         __ATTR_NULL,
 237 };
 238
 239 /**
 240  * backlight_force_update - tell the backlight subsystem that hardware state
 241  *   has changed
 242  * @bd: the backlight device to update
 243  *
 244  * Updates the internal state of the backlight in response to a hardware event,
 245  * and generate a uevent to notify userspace
 246  */
 247 void backlight_force_update(struct backlight_device *bd,
 248                             enum backlight_update_reason reason)
 249 {
 250         mutex_lock(&bd->ops_lock);
 251         if (bd->ops && bd->ops->get_brightness)
 252                 bd->props.brightness = bd->ops->get_brightness(bd);
 253         mutex_unlock(&bd->ops_lock);
 254         backlight_generate_event(bd, reason);
 255 }
 256 EXPORT_SYMBOL(backlight_force_update);
 257
 258 /**
 259  * backlight_device_register - create and register a new object of
 260  *   backlight_device class.
 261  * @name: the name of the new object(must be the same as the name of the
 262  *   respective framebuffer device).
 263  * @parent: a pointer to the parent device
 264  * @devdata: an optional pointer to be stored for private driver use. The
 265  *   methods may retrieve it by using bl_get_data(bd).
 266  * @ops: the backlight operations structure.
 267  *
 268  * Creates and registers new backlight device. Returns either an
 269  * ERR_PTR() or a pointer to the newly allocated device.
 270  */
 271 struct backlight_device *backlight_device_register(const char *name,
 272                 struct device *parent, void *devdata, struct backlight_ops *ops)
 273 {
 274         struct backlight_device *new_bd;
 275         int rc;
 276
 277         pr_debug("backlight_device_register: name=%s\n", name);
 278
 279         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 280         if (!new_bd)
 281                 return ERR_PTR(-ENOMEM);
 282
 283         mutex_init(&new_bd->update_lock);
 284         mutex_init(&new_bd->ops_lock);
 285
 286         new_bd->dev.class = backlight_class;
 287         new_bd->dev.parent = parent;
 288         new_bd->dev.release = bl_device_release;
 289         dev_set_name(&new_bd->dev, name);
 290         dev_set_drvdata(&new_bd->dev, devdata);
 291
 292         rc = device_register(&new_bd->dev);
 293         if (rc) {
 294                 kfree(new_bd);
 295                 return ERR_PTR(rc);
 296         }
 297
 298         rc = backlight_register_fb(new_bd);
 299         if (rc) {
 300                 device_unregister(&new_bd->dev);
 301                 return ERR_PTR(rc);
 302         }
 303
 304         new_bd->ops = ops;
 305
 306 #ifdef CONFIG_PMAC_BACKLIGHT
 307         mutex_lock(&pmac_backlight_mutex);
 308         if (!pmac_backlight)
 309                 pmac_backlight = new_bd;
 310         mutex_unlock(&pmac_backlight_mutex);
 311 #endif
 312
 313         return new_bd;
 314 }
 315 EXPORT_SYMBOL(backlight_device_register);
 316
 317 /**
 318  * backlight_device_unregister - unregisters a backlight device object.
 319  * @bd: the backlight device object to be unregistered and freed.
 320  *
 321  * Unregisters a previously registered via backlight_device_register object.
 322  */
 323 void backlight_device_unregister(struct backlight_device *bd)
 324 {
 325         if (!bd)
 326                 return;
 327
 328 #ifdef CONFIG_PMAC_BACKLIGHT
 329         mutex_lock(&pmac_backlight_mutex);
 330         if (pmac_backlight == bd)
 331                 pmac_backlight = NULL;
 332         mutex_unlock(&pmac_backlight_mutex);
 333 #endif
 334         mutex_lock(&bd->ops_lock);
 335         bd->ops = NULL;
 336         mutex_unlock(&bd->ops_lock);
 337
 338         backlight_unregister_fb(bd);
 339         device_unregister(&bd->dev);
 340 }
 341 EXPORT_SYMBOL(backlight_device_unregister);
 342
 343 static void __exit backlight_class_exit(void)
 344 {
 345         class_destroy(backlight_class);
 346 }
 347
 348 static int __init backlight_class_init(void)
 349 {
 350         backlight_class = class_create(THIS_MODULE, "backlight");
 351         if (IS_ERR(backlight_class)) {
 352                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 353                                 PTR_ERR(backlight_class));
 354                 return PTR_ERR(backlight_class);
 355         }
 356
 357         backlight_class->dev_attrs = bl_device_attributes;
 358         backlight_class->suspend = backlight_suspend;
 359         backlight_class->resume = backlight_resume;
 360         return 0;
 361 }
 362
 363 /*
 364  * if this is compiled into the kernel, we need to ensure that the
 365  * class is registered before users of the class try to register lcd's
 366  */
 367 postcore_initcall(backlight_class_init);
 368 module_exit(backlight_class_exit);
 369
 370 MODULE_LICENSE("GPL");
 371 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 372 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");