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