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 static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
  18 {
  19         int rc = -ENXIO;
  20         struct backlight_device *bd = to_backlight_device(cdev);
  21
  22         down(&bd->sem);
  23         if (likely(bd->props))
  24                 rc = sprintf(buf, "%d\n", bd->props->power);
  25         up(&bd->sem);
  26
  27         return rc;
  28 }
  29
  30 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
  31 {
  32         int rc = -ENXIO;
  33         char *endp;
  34         struct backlight_device *bd = to_backlight_device(cdev);
  35         int power = simple_strtoul(buf, &endp, 0);
  36         size_t size = endp - buf;
  37
  38         if (*endp && isspace(*endp))
  39                 size++;
  40         if (size != count)
  41                 return -EINVAL;
  42
  43         down(&bd->sem);
  44         if (likely(bd->props)) {
  45                 pr_debug("backlight: set power to %d\n", power);
  46                 bd->props->power = power;
  47                 if (likely(bd->props->update_status))
  48                         bd->props->update_status(bd);
  49                 rc = count;
  50         }
  51         up(&bd->sem);
  52
  53         return rc;
  54 }
  55
  56 static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
  57 {
  58         int rc = -ENXIO;
  59         struct backlight_device *bd = to_backlight_device(cdev);
  60
  61         down(&bd->sem);
  62         if (likely(bd->props))
  63                 rc = sprintf(buf, "%d\n", bd->props->brightness);
  64         up(&bd->sem);
  65
  66         return rc;
  67 }
  68
  69 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
  70 {
  71         int rc = -ENXIO;
  72         char *endp;
  73         struct backlight_device *bd = to_backlight_device(cdev);
  74         int brightness = simple_strtoul(buf, &endp, 0);
  75         size_t size = endp - buf;
  76
  77         if (*endp && isspace(*endp))
  78                 size++;
  79         if (size != count)
  80                 return -EINVAL;
  81
  82         down(&bd->sem);
  83         if (likely(bd->props)) {
  84                 if (brightness > bd->props->max_brightness)
  85                         rc = -EINVAL;
  86                 else {
  87                         pr_debug("backlight: set brightness to %d\n",
  88                                  brightness);
  89                         bd->props->brightness = brightness;
  90                         if (likely(bd->props->update_status))
  91                                 bd->props->update_status(bd);
  92                         rc = count;
  93                 }
  94         }
  95         up(&bd->sem);
  96
  97         return rc;
  98 }
  99
 100 static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
 101 {
 102         int rc = -ENXIO;
 103         struct backlight_device *bd = to_backlight_device(cdev);
 104
 105         down(&bd->sem);
 106         if (likely(bd->props))
 107                 rc = sprintf(buf, "%d\n", bd->props->max_brightness);
 108         up(&bd->sem);
 109
 110         return rc;
 111 }
 112
 113 static ssize_t backlight_show_actual_brightness(struct class_device *cdev,
 114                                                 char *buf)
 115 {
 116         int rc = -ENXIO;
 117         struct backlight_device *bd = to_backlight_device(cdev);
 118
 119         down(&bd->sem);
 120         if (likely(bd->props && bd->props->get_brightness))
 121                 rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd));
 122         up(&bd->sem);
 123
 124         return rc;
 125 }
 126
 127 static void backlight_class_release(struct class_device *dev)
 128 {
 129         struct backlight_device *bd = to_backlight_device(dev);
 130         kfree(bd);
 131 }
 132
 133 static struct class backlight_class = {
 134         .name = "backlight",
 135         .release = backlight_class_release,
 136 };
 137
 138 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 139 {                                                               \
 140         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 141         .show   = _show,                                        \
 142         .store  = _store,                                       \
 143 }
 144
 145 static struct class_device_attribute bl_class_device_attributes[] = {
 146         DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
 147         DECLARE_ATTR(brightness, 0644, backlight_show_brightness,
 148                      backlight_store_brightness),
 149         DECLARE_ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 150                      NULL),
 151         DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 152 };
 153
 154 /* This callback gets called when something important happens inside a
 155  * framebuffer driver. We're looking if that important event is blanking,
 156  * and if it is, we're switching backlight power as well ...
 157  */
 158 static int fb_notifier_callback(struct notifier_block *self,
 159                                 unsigned long event, void *data)
 160 {
 161         struct backlight_device *bd;
 162         struct fb_event *evdata =(struct fb_event *)data;
 163
 164         /* If we aren't interested in this event, skip it immediately ... */
 165         if (event != FB_EVENT_BLANK)
 166                 return 0;
 167
 168         bd = container_of(self, struct backlight_device, fb_notif);
 169         down(&bd->sem);
 170         if (bd->props)
 171                 if (!bd->props->check_fb ||
 172                     bd->props->check_fb(evdata->info)) {
 173                         bd->props->fb_blank = *(int *)evdata->data;
 174                         if (likely(bd->props && bd->props->update_status))
 175                                 bd->props->update_status(bd);
 176                 }
 177         up(&bd->sem);
 178         return 0;
 179 }
 180
 181 /**
 182  * backlight_device_register - create and register a new object of
 183  *   backlight_device class.
 184  * @name: the name of the new object(must be the same as the name of the
 185  *   respective framebuffer device).
 186  * @devdata: an optional pointer to be stored in the class_device. The
 187  *   methods may retrieve it by using class_get_devdata(&bd->class_dev).
 188  * @bp: the backlight properties structure.
 189  *
 190  * Creates and registers new backlight class_device. Returns either an
 191  * ERR_PTR() or a pointer to the newly allocated device.
 192  */
 193 struct backlight_device *backlight_device_register(const char *name, void *devdata,
 194                                                    struct backlight_properties *bp)
 195 {
 196         int i, rc;
 197         struct backlight_device *new_bd;
 198
 199         pr_debug("backlight_device_alloc: name=%s\n", name);
 200
 201         new_bd = kmalloc(sizeof(struct backlight_device), GFP_KERNEL);
 202         if (unlikely(!new_bd))
 203                 return ERR_PTR(-ENOMEM);
 204
 205         init_MUTEX(&new_bd->sem);
 206         new_bd->props = bp;
 207         memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev));
 208         new_bd->class_dev.class = &backlight_class;
 209         strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
 210         class_set_devdata(&new_bd->class_dev, devdata);
 211
 212         rc = class_device_register(&new_bd->class_dev);
 213         if (unlikely(rc)) {
 214 error:          kfree(new_bd);
 215                 return ERR_PTR(rc);
 216         }
 217
 218         memset(&new_bd->fb_notif, 0, sizeof(new_bd->fb_notif));
 219         new_bd->fb_notif.notifier_call = fb_notifier_callback;
 220
 221         rc = fb_register_client(&new_bd->fb_notif);
 222         if (unlikely(rc))
 223                 goto error;
 224
 225         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
 226                 rc = class_device_create_file(&new_bd->class_dev,
 227                                               &bl_class_device_attributes[i]);
 228                 if (unlikely(rc)) {
 229                         while (--i >= 0)
 230                                 class_device_remove_file(&new_bd->class_dev,
 231                                                          &bl_class_device_attributes[i]);
 232                         class_device_unregister(&new_bd->class_dev);
 233                         /* No need to kfree(new_bd) since release() method was called */
 234                         return ERR_PTR(rc);
 235                 }
 236         }
 237
 238         return new_bd;
 239 }
 240 EXPORT_SYMBOL(backlight_device_register);
 241
 242 /**
 243  * backlight_device_unregister - unregisters a backlight device object.
 244  * @bd: the backlight device object to be unregistered and freed.
 245  *
 246  * Unregisters a previously registered via backlight_device_register object.
 247  */
 248 void backlight_device_unregister(struct backlight_device *bd)
 249 {
 250         int i;
 251
 252         if (!bd)
 253                 return;
 254
 255         pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);
 256
 257         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
 258                 class_device_remove_file(&bd->class_dev,
 259                                          &bl_class_device_attributes[i]);
 260
 261         down(&bd->sem);
 262         if (likely(bd->props && bd->props->update_status)) {
 263                 bd->props->brightness = 0;
 264                 bd->props->power = 0;
 265                 bd->props->update_status(bd);
 266         }
 267
 268         bd->props = NULL;
 269         up(&bd->sem);
 270
 271         fb_unregister_client(&bd->fb_notif);
 272
 273         class_device_unregister(&bd->class_dev);
 274 }
 275 EXPORT_SYMBOL(backlight_device_unregister);
 276
 277 static void __exit backlight_class_exit(void)
 278 {
 279         class_unregister(&backlight_class);
 280 }
 281
 282 static int __init backlight_class_init(void)
 283 {
 284         return class_register(&backlight_class);
 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");