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