drivers/base/attribute_container.c

   1 /*
   2  * attribute_container.c - implementation of a simple container for classes
   3  *
   4  * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
   5  *
   6  * This file is licensed under GPLv2
   7  *
   8  * The basic idea here is to enable a device to be attached to an
   9  * aritrary numer of classes without having to allocate storage for them.
  10  * Instead, the contained classes select the devices they need to attach
  11  * to via a matching function.
  12  */
  13
  14 #include <linux/attribute_container.h>
  15 #include <linux/init.h>
  16 #include <linux/device.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/list.h>
  20 #include <linux/module.h>
  21
  22 /* This is a private structure used to tie the classdev and the
  23  * container .. it should never be visible outside this file */
  24 struct internal_container {
  25         struct klist_node node;
  26         struct attribute_container *cont;
  27         struct class_device classdev;
  28 };
  29
  30 static void internal_container_klist_get(struct klist_node *n)
  31 {
  32         struct internal_container *ic =
  33                 container_of(n, struct internal_container, node);
  34         class_device_get(&ic->classdev);
  35 }
  36
  37 static void internal_container_klist_put(struct klist_node *n)
  38 {
  39         struct internal_container *ic =
  40                 container_of(n, struct internal_container, node);
  41         class_device_put(&ic->classdev);
  42 }
  43
  44
  45 /**
  46  * attribute_container_classdev_to_container - given a classdev, return the container
  47  *
  48  * @classdev: the class device created by attribute_container_add_device.
  49  *
  50  * Returns the container associated with this classdev.
  51  */
  52 struct attribute_container *
  53 attribute_container_classdev_to_container(struct class_device *classdev)
  54 {
  55         struct internal_container *ic =
  56                 container_of(classdev, struct internal_container, classdev);
  57         return ic->cont;
  58 }
  59 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
  60
  61 static struct list_head attribute_container_list;
  62
  63 static DECLARE_MUTEX(attribute_container_mutex);
  64
  65 /**
  66  * attribute_container_register - register an attribute container
  67  *
  68  * @cont: The container to register.  This must be allocated by the
  69  *        callee and should also be zeroed by it.
  70  */
  71 int
  72 attribute_container_register(struct attribute_container *cont)
  73 {
  74         INIT_LIST_HEAD(&cont->node);
  75         klist_init(&cont->containers,internal_container_klist_get,
  76                    internal_container_klist_put);
  77
  78         down(&attribute_container_mutex);
  79         list_add_tail(&cont->node, &attribute_container_list);
  80         up(&attribute_container_mutex);
  81
  82         return 0;
  83 }
  84 EXPORT_SYMBOL_GPL(attribute_container_register);
  85
  86 /**
  87  * attribute_container_unregister - remove a container registration
  88  *
  89  * @cont: previously registered container to remove
  90  */
  91 int
  92 attribute_container_unregister(struct attribute_container *cont)
  93 {
  94         int retval = -EBUSY;
  95         down(&attribute_container_mutex);
  96         spin_lock(&cont->containers.k_lock);
  97         if (!list_empty(&cont->containers.k_list))
  98                 goto out;
  99         retval = 0;
 100         list_del(&cont->node);
 101  out:
 102         spin_unlock(&cont->containers.k_lock);
 103         up(&attribute_container_mutex);
 104         return retval;
 105
 106 }
 107 EXPORT_SYMBOL_GPL(attribute_container_unregister);
 108
 109 /* private function used as class release */
 110 static void attribute_container_release(struct class_device *classdev)
 111 {
 112         struct internal_container *ic
 113                 = container_of(classdev, struct internal_container, classdev);
 114         struct device *dev = classdev->dev;
 115
 116         kfree(ic);
 117         put_device(dev);
 118 }
 119
 120 /**
 121  * attribute_container_add_device - see if any container is interested in dev
 122  *
 123  * @dev: device to add attributes to
 124  * @fn:  function to trigger addition of class device.
 125  *
 126  * This function allocates storage for the class device(s) to be
 127  * attached to dev (one for each matching attribute_container).  If no
 128  * fn is provided, the code will simply register the class device via
 129  * class_device_add.  If a function is provided, it is expected to add
 130  * the class device at the appropriate time.  One of the things that
 131  * might be necessary is to allocate and initialise the classdev and
 132  * then add it a later time.  To do this, call this routine for
 133  * allocation and initialisation and then use
 134  * attribute_container_device_trigger() to call class_device_add() on
 135  * it.  Note: after this, the class device contains a reference to dev
 136  * which is not relinquished until the release of the classdev.
 137  */
 138 void
 139 attribute_container_add_device(struct device *dev,
 140                                int (*fn)(struct attribute_container *,
 141                                          struct device *,
 142                                          struct class_device *))
 143 {
 144         struct attribute_container *cont;
 145
 146         down(&attribute_container_mutex);
 147         list_for_each_entry(cont, &attribute_container_list, node) {
 148                 struct internal_container *ic;
 149
 150                 if (attribute_container_no_classdevs(cont))
 151                         continue;
 152
 153                 if (!cont->match(cont, dev))
 154                         continue;
 155                 ic = kmalloc(sizeof(struct internal_container), GFP_KERNEL);
 156                 if (!ic) {
 157                         dev_printk(KERN_ERR, dev, "failed to allocate class container\n");
 158                         continue;
 159                 }
 160                 memset(ic, 0, sizeof(struct internal_container));
 161                 ic->cont = cont;
 162                 class_device_initialize(&ic->classdev);
 163                 ic->classdev.dev = get_device(dev);
 164                 ic->classdev.class = cont->class;
 165                 cont->class->release = attribute_container_release;
 166                 strcpy(ic->classdev.class_id, dev->bus_id);
 167                 if (fn)
 168                         fn(cont, dev, &ic->classdev);
 169                 else
 170                         attribute_container_add_class_device(&ic->classdev);
 171                 klist_add_tail(&ic->node, &cont->containers);
 172         }
 173         up(&attribute_container_mutex);
 174 }
 175
 176 /* FIXME: can't break out of this unless klist_iter_exit is also
 177  * called before doing the break
 178  */
 179 #define klist_for_each_entry(pos, head, member, iter) \
 180         for (klist_iter_init(head, iter); (pos = ({ \
 181                 struct klist_node *n = klist_next(iter); \
 182                 n ? container_of(n, typeof(*pos), member) : \
 183                         ({ klist_iter_exit(iter) ; NULL; }); \
 184         }) ) != NULL; )
 185
 186
 187 /**
 188  * attribute_container_remove_device - make device eligible for removal.
 189  *
 190  * @dev:  The generic device
 191  * @fn:   A function to call to remove the device
 192  *
 193  * This routine triggers device removal.  If fn is NULL, then it is
 194  * simply done via class_device_unregister (note that if something
 195  * still has a reference to the classdev, then the memory occupied
 196  * will not be freed until the classdev is released).  If you want a
 197  * two phase release: remove from visibility and then delete the
 198  * device, then you should use this routine with a fn that calls
 199  * class_device_del() and then use
 200  * attribute_container_device_trigger() to do the final put on the
 201  * classdev.
 202  */
 203 void
 204 attribute_container_remove_device(struct device *dev,
 205                                   void (*fn)(struct attribute_container *,
 206                                              struct device *,
 207                                              struct class_device *))
 208 {
 209         struct attribute_container *cont;
 210
 211         down(&attribute_container_mutex);
 212         list_for_each_entry(cont, &attribute_container_list, node) {
 213                 struct internal_container *ic;
 214                 struct klist_iter iter;
 215
 216                 if (attribute_container_no_classdevs(cont))
 217                         continue;
 218
 219                 if (!cont->match(cont, dev))
 220                         continue;
 221
 222                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 223                         if (dev != ic->classdev.dev)
 224                                 continue;
 225                         klist_del(&ic->node);
 226                         if (fn)
 227                                 fn(cont, dev, &ic->classdev);
 228                         else {
 229                                 attribute_container_remove_attrs(&ic->classdev);
 230                                 class_device_unregister(&ic->classdev);
 231                         }
 232                 }
 233         }
 234         up(&attribute_container_mutex);
 235 }
 236 EXPORT_SYMBOL_GPL(attribute_container_remove_device);
 237
 238 /**
 239  * attribute_container_device_trigger - execute a trigger for each matching classdev
 240  *
 241  * @dev:  The generic device to run the trigger for
 242  * @fn    the function to execute for each classdev.
 243  *
 244  * This funcion is for executing a trigger when you need to know both
 245  * the container and the classdev.  If you only care about the
 246  * container, then use attribute_container_trigger() instead.
 247  */
 248 void
 249 attribute_container_device_trigger(struct device *dev,
 250                                    int (*fn)(struct attribute_container *,
 251                                              struct device *,
 252                                              struct class_device *))
 253 {
 254         struct attribute_container *cont;
 255
 256         down(&attribute_container_mutex);
 257         list_for_each_entry(cont, &attribute_container_list, node) {
 258                 struct internal_container *ic;
 259                 struct klist_iter iter;
 260
 261                 if (!cont->match(cont, dev))
 262                         continue;
 263
 264                 if (attribute_container_no_classdevs(cont)) {
 265                         fn(cont, dev, NULL);
 266                         continue;
 267                 }
 268
 269                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 270                         if (dev == ic->classdev.dev)
 271                                 fn(cont, dev, &ic->classdev);
 272                 }
 273         }
 274         up(&attribute_container_mutex);
 275 }
 276 EXPORT_SYMBOL_GPL(attribute_container_device_trigger);
 277
 278 /**
 279  * attribute_container_trigger - trigger a function for each matching container
 280  *
 281  * @dev:  The generic device to activate the trigger for
 282  * @fn:   the function to trigger
 283  *
 284  * This routine triggers a function that only needs to know the
 285  * matching containers (not the classdev) associated with a device.
 286  * It is more lightweight than attribute_container_device_trigger, so
 287  * should be used in preference unless the triggering function
 288  * actually needs to know the classdev.
 289  */
 290 void
 291 attribute_container_trigger(struct device *dev,
 292                             int (*fn)(struct attribute_container *,
 293                                       struct device *))
 294 {
 295         struct attribute_container *cont;
 296
 297         down(&attribute_container_mutex);
 298         list_for_each_entry(cont, &attribute_container_list, node) {
 299                 if (cont->match(cont, dev))
 300                         fn(cont, dev);
 301         }
 302         up(&attribute_container_mutex);
 303 }
 304 EXPORT_SYMBOL_GPL(attribute_container_trigger);
 305
 306 /**
 307  * attribute_container_add_attrs - add attributes
 308  *
 309  * @classdev: The class device
 310  *
 311  * This simply creates all the class device sysfs files from the
 312  * attributes listed in the container
 313  */
 314 int
 315 attribute_container_add_attrs(struct class_device *classdev)
 316 {
 317         struct attribute_container *cont =
 318                 attribute_container_classdev_to_container(classdev);
 319         struct class_device_attribute **attrs = cont->attrs;
 320         int i, error;
 321
 322         if (!attrs)
 323                 return 0;
 324
 325         for (i = 0; attrs[i]; i++) {
 326                 error = class_device_create_file(classdev, attrs[i]);
 327                 if (error)
 328                         return error;
 329         }
 330
 331         return 0;
 332 }
 333 EXPORT_SYMBOL_GPL(attribute_container_add_attrs);
 334
 335 /**
 336  * attribute_container_add_class_device - same function as class_device_add
 337  *
 338  * @classdev:   the class device to add
 339  *
 340  * This performs essentially the same function as class_device_add except for
 341  * attribute containers, namely add the classdev to the system and then
 342  * create the attribute files
 343  */
 344 int
 345 attribute_container_add_class_device(struct class_device *classdev)
 346 {
 347         int error = class_device_add(classdev);
 348         if (error)
 349                 return error;
 350         return attribute_container_add_attrs(classdev);
 351 }
 352 EXPORT_SYMBOL_GPL(attribute_container_add_class_device);
 353
 354 /**
 355  * attribute_container_add_class_device_adapter - simple adapter for triggers
 356  *
 357  * This function is identical to attribute_container_add_class_device except
 358  * that it is designed to be called from the triggers
 359  */
 360 int
 361 attribute_container_add_class_device_adapter(struct attribute_container *cont,
 362                                              struct device *dev,
 363                                              struct class_device *classdev)
 364 {
 365         return attribute_container_add_class_device(classdev);
 366 }
 367 EXPORT_SYMBOL_GPL(attribute_container_add_class_device_adapter);
 368
 369 /**
 370  * attribute_container_remove_attrs - remove any attribute files
 371  *
 372  * @classdev: The class device to remove the files from
 373  *
 374  */
 375 void
 376 attribute_container_remove_attrs(struct class_device *classdev)
 377 {
 378         struct attribute_container *cont =
 379                 attribute_container_classdev_to_container(classdev);
 380         struct class_device_attribute **attrs = cont->attrs;
 381         int i;
 382
 383         if (!attrs)
 384                 return;
 385
 386         for (i = 0; attrs[i]; i++)
 387                 class_device_remove_file(classdev, attrs[i]);
 388 }
 389 EXPORT_SYMBOL_GPL(attribute_container_remove_attrs);
 390
 391 /**
 392  * attribute_container_class_device_del - equivalent of class_device_del
 393  *
 394  * @classdev: the class device
 395  *
 396  * This function simply removes all the attribute files and then calls
 397  * class_device_del.
 398  */
 399 void
 400 attribute_container_class_device_del(struct class_device *classdev)
 401 {
 402         attribute_container_remove_attrs(classdev);
 403         class_device_del(classdev);
 404 }
 405 EXPORT_SYMBOL_GPL(attribute_container_class_device_del);
 406
 407 /**
 408  * attribute_container_find_class_device - find the corresponding class_device
 409  *
 410  * @cont:       the container
 411  * @dev:        the generic device
 412  *
 413  * Looks up the device in the container's list of class devices and returns
 414  * the corresponding class_device.
 415  */
 416 struct class_device *
 417 attribute_container_find_class_device(struct attribute_container *cont,
 418                                       struct device *dev)
 419 {
 420         struct class_device *cdev = NULL;
 421         struct internal_container *ic;
 422         struct klist_iter iter;
 423
 424         klist_for_each_entry(ic, &cont->containers, node, &iter) {
 425                 if (ic->classdev.dev == dev) {
 426                         cdev = &ic->classdev;
 427                         /* FIXME: must exit iterator then break */
 428                         klist_iter_exit(&iter);
 429                         break;
 430                 }
 431         }
 432
 433         return cdev;
 434 }
 435 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
 436
 437 int __init
 438 attribute_container_init(void)
 439 {
 440         INIT_LIST_HEAD(&attribute_container_list);
 441         return 0;
 442 }