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