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