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