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
 156                 ic = kzalloc(sizeof(*ic), GFP_KERNEL);
 157                 if (!ic) {
 158                         dev_printk(KERN_ERR, dev, "failed to allocate class container\n");
 159                         continue;
 160                 }
 161
 162                 ic->cont = cont;
 163                 class_device_initialize(&ic->classdev);
 164                 ic->classdev.dev = get_device(dev);
 165                 ic->classdev.class = cont->class;
 166                 cont->class->release = attribute_container_release;
 167                 strcpy(ic->classdev.class_id, dev->bus_id);
 168                 if (fn)
 169                         fn(cont, dev, &ic->classdev);
 170                 else
 171                         attribute_container_add_class_device(&ic->classdev);
 172                 klist_add_tail(&ic->node, &cont->containers);
 173         }
 174         up(&attribute_container_mutex);
 175 }
 176
 177 /* FIXME: can't break out of this unless klist_iter_exit is also
 178  * called before doing the break
 179  */
 180 #define klist_for_each_entry(pos, head, member, iter) \
 181         for (klist_iter_init(head, iter); (pos = ({ \
 182                 struct klist_node *n = klist_next(iter); \
 183                 n ? container_of(n, typeof(*pos), member) : \
 184                         ({ klist_iter_exit(iter) ; NULL; }); \
 185         }) ) != NULL; )
 186
 187
 188 /**
 189  * attribute_container_remove_device - make device eligible for removal.
 190  *
 191  * @dev:  The generic device
 192  * @fn:   A function to call to remove the device
 193  *
 194  * This routine triggers device removal.  If fn is NULL, then it is
 195  * simply done via class_device_unregister (note that if something
 196  * still has a reference to the classdev, then the memory occupied
 197  * will not be freed until the classdev is released).  If you want a
 198  * two phase release: remove from visibility and then delete the
 199  * device, then you should use this routine with a fn that calls
 200  * class_device_del() and then use
 201  * attribute_container_device_trigger() to do the final put on the
 202  * classdev.
 203  */
 204 void
 205 attribute_container_remove_device(struct device *dev,
 206                                   void (*fn)(struct attribute_container *,
 207                                              struct device *,
 208                                              struct class_device *))
 209 {
 210         struct attribute_container *cont;
 211
 212         down(&attribute_container_mutex);
 213         list_for_each_entry(cont, &attribute_container_list, node) {
 214                 struct internal_container *ic;
 215                 struct klist_iter iter;
 216
 217                 if (attribute_container_no_classdevs(cont))
 218                         continue;
 219
 220                 if (!cont->match(cont, dev))
 221                         continue;
 222
 223                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 224                         if (dev != ic->classdev.dev)
 225                                 continue;
 226                         klist_del(&ic->node);
 227                         if (fn)
 228                                 fn(cont, dev, &ic->classdev);
 229                         else {
 230                                 attribute_container_remove_attrs(&ic->classdev);
 231                                 class_device_unregister(&ic->classdev);
 232                         }
 233                 }
 234         }
 235         up(&attribute_container_mutex);
 236 }
 237 EXPORT_SYMBOL_GPL(attribute_container_remove_device);
 238
 239 /**
 240  * attribute_container_device_trigger - execute a trigger for each matching classdev
 241  *
 242  * @dev:  The generic device to run the trigger for
 243  * @fn    the function to execute for each classdev.
 244  *
 245  * This funcion is for executing a trigger when you need to know both
 246  * the container and the classdev.  If you only care about the
 247  * container, then use attribute_container_trigger() instead.
 248  */
 249 void
 250 attribute_container_device_trigger(struct device *dev,
 251                                    int (*fn)(struct attribute_container *,
 252                                              struct device *,
 253                                              struct class_device *))
 254 {
 255         struct attribute_container *cont;
 256
 257         down(&attribute_container_mutex);
 258         list_for_each_entry(cont, &attribute_container_list, node) {
 259                 struct internal_container *ic;
 260                 struct klist_iter iter;
 261
 262                 if (!cont->match(cont, dev))
 263                         continue;
 264
 265                 if (attribute_container_no_classdevs(cont)) {
 266                         fn(cont, dev, NULL);
 267                         continue;
 268                 }
 269
 270                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 271                         if (dev == ic->classdev.dev)
 272                                 fn(cont, dev, &ic->classdev);
 273                 }
 274         }
 275         up(&attribute_container_mutex);
 276 }
 277 EXPORT_SYMBOL_GPL(attribute_container_device_trigger);
 278
 279 /**
 280  * attribute_container_trigger - trigger a function for each matching container
 281  *
 282  * @dev:  The generic device to activate the trigger for
 283  * @fn:   the function to trigger
 284  *
 285  * This routine triggers a function that only needs to know the
 286  * matching containers (not the classdev) associated with a device.
 287  * It is more lightweight than attribute_container_device_trigger, so
 288  * should be used in preference unless the triggering function
 289  * actually needs to know the classdev.
 290  */
 291 void
 292 attribute_container_trigger(struct device *dev,
 293                             int (*fn)(struct attribute_container *,
 294                                       struct device *))
 295 {
 296         struct attribute_container *cont;
 297
 298         down(&attribute_container_mutex);
 299         list_for_each_entry(cont, &attribute_container_list, node) {
 300                 if (cont->match(cont, dev))
 301                         fn(cont, dev);
 302         }
 303         up(&attribute_container_mutex);
 304 }
 305 EXPORT_SYMBOL_GPL(attribute_container_trigger);
 306
 307 /**
 308  * attribute_container_add_attrs - add attributes
 309  *
 310  * @classdev: The class device
 311  *
 312  * This simply creates all the class device sysfs files from the
 313  * attributes listed in the container
 314  */
 315 int
 316 attribute_container_add_attrs(struct class_device *classdev)
 317 {
 318         struct attribute_container *cont =
 319                 attribute_container_classdev_to_container(classdev);
 320         struct class_device_attribute **attrs = cont->attrs;
 321         int i, error;
 322
 323         if (!attrs)
 324                 return 0;
 325
 326         for (i = 0; attrs[i]; i++) {
 327                 error = class_device_create_file(classdev, attrs[i]);
 328                 if (error)
 329                         return error;
 330         }
 331
 332         return 0;
 333 }
 334 EXPORT_SYMBOL_GPL(attribute_container_add_attrs);
 335
 336 /**
 337  * attribute_container_add_class_device - same function as class_device_add
 338  *
 339  * @classdev:   the class device to add
 340  *
 341  * This performs essentially the same function as class_device_add except for
 342  * attribute containers, namely add the classdev to the system and then
 343  * create the attribute files
 344  */
 345 int
 346 attribute_container_add_class_device(struct class_device *classdev)
 347 {
 348         int error = class_device_add(classdev);
 349         if (error)
 350                 return error;
 351         return attribute_container_add_attrs(classdev);
 352 }
 353 EXPORT_SYMBOL_GPL(attribute_container_add_class_device);
 354
 355 /**
 356  * attribute_container_add_class_device_adapter - simple adapter for triggers
 357  *
 358  * This function is identical to attribute_container_add_class_device except
 359  * that it is designed to be called from the triggers
 360  */
 361 int
 362 attribute_container_add_class_device_adapter(struct attribute_container *cont,
 363                                              struct device *dev,
 364                                              struct class_device *classdev)
 365 {
 366         return attribute_container_add_class_device(classdev);
 367 }
 368 EXPORT_SYMBOL_GPL(attribute_container_add_class_device_adapter);
 369
 370 /**
 371  * attribute_container_remove_attrs - remove any attribute files
 372  *
 373  * @classdev: The class device to remove the files from
 374  *
 375  */
 376 void
 377 attribute_container_remove_attrs(struct class_device *classdev)
 378 {
 379         struct attribute_container *cont =
 380                 attribute_container_classdev_to_container(classdev);
 381         struct class_device_attribute **attrs = cont->attrs;
 382         int i;
 383
 384         if (!attrs)
 385                 return;
 386
 387         for (i = 0; attrs[i]; i++)
 388                 class_device_remove_file(classdev, attrs[i]);
 389 }
 390 EXPORT_SYMBOL_GPL(attribute_container_remove_attrs);
 391
 392 /**
 393  * attribute_container_class_device_del - equivalent of class_device_del
 394  *
 395  * @classdev: the class device
 396  *
 397  * This function simply removes all the attribute files and then calls
 398  * class_device_del.
 399  */
 400 void
 401 attribute_container_class_device_del(struct class_device *classdev)
 402 {
 403         attribute_container_remove_attrs(classdev);
 404         class_device_del(classdev);
 405 }
 406 EXPORT_SYMBOL_GPL(attribute_container_class_device_del);
 407
 408 /**
 409  * attribute_container_find_class_device - find the corresponding class_device
 410  *
 411  * @cont:       the container
 412  * @dev:        the generic device
 413  *
 414  * Looks up the device in the container's list of class devices and returns
 415  * the corresponding class_device.
 416  */
 417 struct class_device *
 418 attribute_container_find_class_device(struct attribute_container *cont,
 419                                       struct device *dev)
 420 {
 421         struct class_device *cdev = NULL;
 422         struct internal_container *ic;
 423         struct klist_iter iter;
 424
 425         klist_for_each_entry(ic, &cont->containers, node, &iter) {
 426                 if (ic->classdev.dev == dev) {
 427                         cdev = &ic->classdev;
 428                         /* FIXME: must exit iterator then break */
 429                         klist_iter_exit(&iter);
 430                         break;
 431                 }
 432         }
 433
 434         return cdev;
 435 }
 436 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
 437
 438 int __init
 439 attribute_container_init(void)
 440 {
 441         INIT_LIST_HEAD(&attribute_container_list);
 442         return 0;
 443 }