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 = -ENXIO;
  84         char *endp;
  85         struct backlight_device *bd = to_backlight_device(dev);
  86         int power = simple_strtoul(buf, &endp, 0);
  87         size_t size = endp - buf;
  88
  89         if (*endp && isspace(*endp))
  90                 size++;
  91         if (size != count)
  92                 return -EINVAL;
  93
  94         mutex_lock(&bd->ops_lock);
  95         if (bd->ops) {
  96                 pr_debug("backlight: set power to %d\n", power);
  97                 if (bd->props.power != power) {
  98                         bd->props.power = power;
  99                         backlight_update_status(bd);
 100                 }
 101                 rc = count;
 102         }
 103         mutex_unlock(&bd->ops_lock);
 104
 105         return rc;
 106 }
 107
 108 static ssize_t backlight_show_brightness(struct device *dev,
 109                 struct device_attribute *attr, char *buf)
 110 {
 111         struct backlight_device *bd = to_backlight_device(dev);
 112
 113         return sprintf(buf, "%d\n", bd->props.brightness);
 114 }
 115
 116 static ssize_t backlight_store_brightness(struct device *dev,
 117                 struct device_attribute *attr, const char *buf, size_t count)
 118 {
 119         int rc = -ENXIO;
 120         char *endp;
 121         struct backlight_device *bd = to_backlight_device(dev);
 122         int brightness = simple_strtoul(buf, &endp, 0);
 123         size_t size = endp - buf;
 124
 125         if (*endp && isspace(*endp))
 126                 size++;
 127         if (size != count)
 128                 return -EINVAL;
 129
 130         mutex_lock(&bd->ops_lock);
 131         if (bd->ops) {
 132                 if (brightness > bd->props.max_brightness)
 133                         rc = -EINVAL;
 134                 else {
 135                         pr_debug("backlight: set brightness to %d\n",
 136                                  brightness);
 137                         if (bd->props.brightness != brightness) {
 138                                 bd->props.brightness = brightness;
 139                                 backlight_update_status(bd);
 140                         }
 141                         rc = count;
 142                 }
 143         }
 144         mutex_unlock(&bd->ops_lock);
 145
 146         return rc;
 147 }
 148
 149 static ssize_t backlight_show_max_brightness(struct device *dev,
 150                 struct device_attribute *attr, char *buf)
 151 {
 152         struct backlight_device *bd = to_backlight_device(dev);
 153
 154         return sprintf(buf, "%d\n", bd->props.max_brightness);
 155 }
 156
 157 static ssize_t backlight_show_actual_brightness(struct device *dev,
 158                 struct device_attribute *attr, char *buf)
 159 {
 160         int rc = -ENXIO;
 161         struct backlight_device *bd = to_backlight_device(dev);
 162
 163         mutex_lock(&bd->ops_lock);
 164         if (bd->ops && bd->ops->get_brightness)
 165                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 166         mutex_unlock(&bd->ops_lock);
 167
 168         return rc;
 169 }
 170
 171 static struct class *backlight_class;
 172
 173 static void bl_device_release(struct device *dev)
 174 {
 175         struct backlight_device *bd = to_backlight_device(dev);
 176         kfree(bd);
 177 }
 178
 179 static struct device_attribute bl_device_attributes[] = {
 180         __ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
 181         __ATTR(brightness, 0644, backlight_show_brightness,
 182                      backlight_store_brightness),
 183         __ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 184                      NULL),
 185         __ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 186         __ATTR_NULL,
 187 };
 188
 189 /**
 190  * backlight_device_register - create and register a new object of
 191  *   backlight_device class.
 192  * @name: the name of the new object(must be the same as the name of the
 193  *   respective framebuffer device).
 194  * @devdata: an optional pointer to be stored for private driver use. The
 195  *   methods may retrieve it by using bl_get_data(bd).
 196  * @ops: the backlight operations structure.
 197  *
 198  * Creates and registers new backlight device. Returns either an
 199  * ERR_PTR() or a pointer to the newly allocated device.
 200  */
 201 struct backlight_device *backlight_device_register(const char *name,
 202                 struct device *parent, void *devdata, struct backlight_ops *ops)
 203 {
 204         struct backlight_device *new_bd;
 205         int rc;
 206
 207         pr_debug("backlight_device_register: name=%s\n", name);
 208
 209         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 210         if (!new_bd)
 211                 return ERR_PTR(-ENOMEM);
 212
 213         mutex_init(&new_bd->update_lock);
 214         mutex_init(&new_bd->ops_lock);
 215
 216         new_bd->dev.class = backlight_class;
 217         new_bd->dev.parent = parent;
 218         new_bd->dev.release = bl_device_release;
 219         strlcpy(new_bd->dev.bus_id, name, BUS_ID_SIZE);
 220         dev_set_drvdata(&new_bd->dev, devdata);
 221
 222         rc = device_register(&new_bd->dev);
 223         if (rc) {
 224                 kfree(new_bd);
 225                 return ERR_PTR(rc);
 226         }
 227
 228         rc = backlight_register_fb(new_bd);
 229         if (rc) {
 230                 device_unregister(&new_bd->dev);
 231                 return ERR_PTR(rc);
 232         }
 233
 234         new_bd->ops = ops;
 235
 236 #ifdef CONFIG_PMAC_BACKLIGHT
 237         mutex_lock(&pmac_backlight_mutex);
 238         if (!pmac_backlight)
 239                 pmac_backlight = new_bd;
 240         mutex_unlock(&pmac_backlight_mutex);
 241 #endif
 242
 243         return new_bd;
 244 }
 245 EXPORT_SYMBOL(backlight_device_register);
 246
 247 /**
 248  * backlight_device_unregister - unregisters a backlight device object.
 249  * @bd: the backlight device object to be unregistered and freed.
 250  *
 251  * Unregisters a previously registered via backlight_device_register object.
 252  */
 253 void backlight_device_unregister(struct backlight_device *bd)
 254 {
 255         if (!bd)
 256                 return;
 257
 258 #ifdef CONFIG_PMAC_BACKLIGHT
 259         mutex_lock(&pmac_backlight_mutex);
 260         if (pmac_backlight == bd)
 261                 pmac_backlight = NULL;
 262         mutex_unlock(&pmac_backlight_mutex);
 263 #endif
 264         mutex_lock(&bd->ops_lock);
 265         bd->ops = NULL;
 266         mutex_unlock(&bd->ops_lock);
 267
 268         backlight_unregister_fb(bd);
 269         device_unregister(&bd->dev);
 270 }
 271 EXPORT_SYMBOL(backlight_device_unregister);
 272
 273 static void __exit backlight_class_exit(void)
 274 {
 275         class_destroy(backlight_class);
 276 }
 277
 278 static int __init backlight_class_init(void)
 279 {
 280         backlight_class = class_create(THIS_MODULE, "backlight");
 281         if (IS_ERR(backlight_class)) {
 282                 printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 283                                 PTR_ERR(backlight_class));
 284                 return PTR_ERR(backlight_class);
 285         }
 286
 287         backlight_class->dev_attrs = bl_device_attributes;
 288         return 0;
 289 }
 290
 291 /*
 292  * if this is compiled into the kernel, we need to ensure that the
 293  * class is registered before users of the class try to register lcd's
 294  */
 295 postcore_initcall(backlight_class_init);
 296 module_exit(backlight_class_exit);
 297
 298 MODULE_LICENSE("GPL");
 299 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 300 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");