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