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