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 #include <asm/bug.h>
  17
  18 static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
  19 {
  20         int rc;
  21         struct backlight_device *bd = to_backlight_device(cdev);
  22
  23         down(&bd->sem);
  24         if (likely(bd->props && bd->props->get_power))
  25                 rc = sprintf(buf, "%d\n", bd->props->get_power(bd));
  26         else
  27                 rc = -ENXIO;
  28         up(&bd->sem);
  29
  30         return rc;
  31 }
  32
  33 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
  34 {
  35         int rc, power;
  36         char *endp;
  37         struct backlight_device *bd = to_backlight_device(cdev);
  38
  39         power = simple_strtoul(buf, &endp, 0);
  40         if (*endp && !isspace(*endp))
  41                 return -EINVAL;
  42
  43         down(&bd->sem);
  44         if (likely(bd->props && bd->props->set_power)) {
  45                 pr_debug("backlight: set power to %d\n", power);
  46                 bd->props->set_power(bd, power);
  47                 rc = count;
  48         } else
  49                 rc = -ENXIO;
  50         up(&bd->sem);
  51
  52         return rc;
  53 }
  54
  55 static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
  56 {
  57         int rc;
  58         struct backlight_device *bd = to_backlight_device(cdev);
  59
  60         down(&bd->sem);
  61         if (likely(bd->props && bd->props->get_brightness))
  62                 rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd));
  63         else
  64                 rc = -ENXIO;
  65         up(&bd->sem);
  66
  67         return rc;
  68 }
  69
  70 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
  71 {
  72         int rc, brightness;
  73         char *endp;
  74         struct backlight_device *bd = to_backlight_device(cdev);
  75
  76         brightness = simple_strtoul(buf, &endp, 0);
  77         if (*endp && !isspace(*endp))
  78                 return -EINVAL;
  79
  80         down(&bd->sem);
  81         if (likely(bd->props && bd->props->set_brightness)) {
  82                 pr_debug("backlight: set brightness to %d\n", brightness);
  83                 bd->props->set_brightness(bd, brightness);
  84                 rc = count;
  85         } else
  86                 rc = -ENXIO;
  87         up(&bd->sem);
  88
  89         return rc;
  90 }
  91
  92 static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
  93 {
  94         int rc;
  95         struct backlight_device *bd = to_backlight_device(cdev);
  96
  97         down(&bd->sem);
  98         if (likely(bd->props))
  99                 rc = sprintf(buf, "%d\n", bd->props->max_brightness);
 100         else
 101                 rc = -ENXIO;
 102         up(&bd->sem);
 103
 104         return rc;
 105 }
 106
 107 static void backlight_class_release(struct class_device *dev)
 108 {
 109         struct backlight_device *bd = to_backlight_device(dev);
 110         kfree(bd);
 111 }
 112
 113 static struct class backlight_class = {
 114         .name = "backlight",
 115         .release = backlight_class_release,
 116 };
 117
 118 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 119 {                                                               \
 120         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 121         .show   = _show,                                        \
 122         .store  = _store,                                       \
 123 }
 124
 125 static struct class_device_attribute bl_class_device_attributes[] = {
 126         DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
 127         DECLARE_ATTR(brightness, 0644, backlight_show_brightness, backlight_store_brightness),
 128         DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 129 };
 130
 131 /* This callback gets called when something important happens inside a
 132  * framebuffer driver. We're looking if that important event is blanking,
 133  * and if it is, we're switching backlight power as well ...
 134  */
 135 static int fb_notifier_callback(struct notifier_block *self,
 136                                 unsigned long event, void *data)
 137 {
 138         struct backlight_device *bd;
 139         struct fb_event *evdata =(struct fb_event *)data;
 140
 141         /* If we aren't interested in this event, skip it immediately ... */
 142         if (event != FB_EVENT_BLANK)
 143                 return 0;
 144
 145         bd = container_of(self, struct backlight_device, fb_notif);
 146         down(&bd->sem);
 147         if (bd->props)
 148                 if (!bd->props->check_fb || bd->props->check_fb(evdata->info))
 149                         bd->props->set_power(bd, *(int *)evdata->data);
 150         up(&bd->sem);
 151         return 0;
 152 }
 153
 154 /**
 155  * backlight_device_register - create and register a new object of
 156  *   backlight_device class.
 157  * @name: the name of the new object(must be the same as the name of the
 158  *   respective framebuffer device).
 159  * @devdata: an optional pointer to be stored in the class_device. The
 160  *   methods may retrieve it by using class_get_devdata(&bd->class_dev).
 161  * @bp: the backlight properties structure.
 162  *
 163  * Creates and registers new backlight class_device. Returns either an
 164  * ERR_PTR() or a pointer to the newly allocated device.
 165  */
 166 struct backlight_device *backlight_device_register(const char *name, void *devdata,
 167                                                    struct backlight_properties *bp)
 168 {
 169         int i, rc;
 170         struct backlight_device *new_bd;
 171
 172         pr_debug("backlight_device_alloc: name=%s\n", name);
 173
 174         new_bd = kmalloc(sizeof(struct backlight_device), GFP_KERNEL);
 175         if (unlikely(!new_bd))
 176                 return ERR_PTR(ENOMEM);
 177
 178         init_MUTEX(&new_bd->sem);
 179         new_bd->props = bp;
 180         memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev));
 181         new_bd->class_dev.class = &backlight_class;
 182         strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
 183         class_set_devdata(&new_bd->class_dev, devdata);
 184
 185         rc = class_device_register(&new_bd->class_dev);
 186         if (unlikely(rc)) {
 187 error:          kfree(new_bd);
 188                 return ERR_PTR(rc);
 189         }
 190
 191         memset(&new_bd->fb_notif, 0, sizeof(new_bd->fb_notif));
 192         new_bd->fb_notif.notifier_call = fb_notifier_callback;
 193
 194         rc = fb_register_client(&new_bd->fb_notif);
 195         if (unlikely(rc))
 196                 goto error;
 197
 198         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
 199                 rc = class_device_create_file(&new_bd->class_dev,
 200                                               &bl_class_device_attributes[i]);
 201                 if (unlikely(rc)) {
 202                         while (--i >= 0)
 203                                 class_device_remove_file(&new_bd->class_dev,
 204                                                          &bl_class_device_attributes[i]);
 205                         class_device_unregister(&new_bd->class_dev);
 206                         /* No need to kfree(new_bd) since release() method was called */
 207                         return ERR_PTR(rc);
 208                 }
 209         }
 210
 211         return new_bd;
 212 }
 213 EXPORT_SYMBOL(backlight_device_register);
 214
 215 /**
 216  * backlight_device_unregister - unregisters a backlight device object.
 217  * @bd: the backlight device object to be unregistered and freed.
 218  *
 219  * Unregisters a previously registered via backlight_device_register object.
 220  */
 221 void backlight_device_unregister(struct backlight_device *bd)
 222 {
 223         int i;
 224
 225         if (!bd)
 226                 return;
 227
 228         pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);
 229
 230         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
 231                 class_device_remove_file(&bd->class_dev,
 232                                          &bl_class_device_attributes[i]);
 233
 234         down(&bd->sem);
 235         bd->props = NULL;
 236         up(&bd->sem);
 237
 238         fb_unregister_client(&bd->fb_notif);
 239
 240         class_device_unregister(&bd->class_dev);
 241 }
 242 EXPORT_SYMBOL(backlight_device_unregister);
 243
 244 static void __exit backlight_class_exit(void)
 245 {
 246         class_unregister(&backlight_class);
 247 }
 248
 249 static int __init backlight_class_init(void)
 250 {
 251         return class_register(&backlight_class);
 252 }
 253
 254 /*
 255  * if this is compiled into the kernel, we need to ensure that the
 256  * class is registered before users of the class try to register lcd's
 257  */
 258 postcore_initcall(backlight_class_init);
 259 module_exit(backlight_class_exit);
 260
 261 MODULE_LICENSE("GPL");
 262 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 263 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");