drivers/base/attribute_container.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * attribute_container.c - implementation of a simple container for classes
   4  *
   5  * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
   6  *
   7  * The basic idea here is to enable a device to be attached to an
   8  * aritrary numer of classes without having to allocate storage for them.
   9  * Instead, the contained classes select the devices they need to attach
  10  * to via a matching function.
  11  */
  12
  13 #include <linux/attribute_container.h>
  14 #include <linux/device.h>
  15 #include <linux/kernel.h>
  16 #include <linux/slab.h>
  17 #include <linux/list.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20
  21 #include "base.h"
  22
  23 /* This is a private structure used to tie the classdev and the
  24  * container .. it should never be visible outside this file */
  25 struct internal_container {
  26         struct klist_node node;
  27         struct attribute_container *cont;
  28         struct device classdev;
  29 };
  30
  31 static void internal_container_klist_get(struct klist_node *n)
  32 {
  33         struct internal_container *ic =
  34                 container_of(n, struct internal_container, node);
  35         get_device(&ic->classdev);
  36 }
  37
  38 static void internal_container_klist_put(struct klist_node *n)
  39 {
  40         struct internal_container *ic =
  41                 container_of(n, struct internal_container, node);
  42         put_device(&ic->classdev);
  43 }
  44
  45
  46 /**
  47  * attribute_container_classdev_to_container - given a classdev, return the container
  48  *
  49  * @classdev: the class device created by attribute_container_add_device.
  50  *
  51  * Returns the container associated with this classdev.
  52  */
  53 struct attribute_container *
  54 attribute_container_classdev_to_container(struct device *classdev)
  55 {
  56         struct internal_container *ic =
  57                 container_of(classdev, struct internal_container, classdev);
  58         return ic->cont;
  59 }
  60 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
  61
  62 static LIST_HEAD(attribute_container_list);
  63
  64 static DEFINE_MUTEX(attribute_container_mutex);
  65
  66 /**
  67  * attribute_container_register - register an attribute container
  68  *
  69  * @cont: The container to register.  This must be allocated by the
  70  *        callee and should also be zeroed by it.
  71  */
  72 int
  73 attribute_container_register(struct attribute_container *cont)
  74 {
  75         INIT_LIST_HEAD(&cont->node);
  76         klist_init(&cont->containers, internal_container_klist_get,
  77                    internal_container_klist_put);
  78
  79         mutex_lock(&attribute_container_mutex);
  80         list_add_tail(&cont->node, &attribute_container_list);
  81         mutex_unlock(&attribute_container_mutex);
  82
  83         return 0;
  84 }
  85 EXPORT_SYMBOL_GPL(attribute_container_register);
  86
  87 /**
  88  * attribute_container_unregister - remove a container registration
  89  *
  90  * @cont: previously registered container to remove
  91  */
  92 int
  93 attribute_container_unregister(struct attribute_container *cont)
  94 {
  95         int retval = -EBUSY;
  96
  97         mutex_lock(&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         mutex_unlock(&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 device *classdev)
 113 {
 114         struct internal_container *ic
 115                 = container_of(classdev, struct internal_container, classdev);
 116         struct device *dev = classdev->parent;
 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  * 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 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 device *))
 145 {
 146         struct attribute_container *cont;
 147
 148         mutex_lock(&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_err(dev, "failed to allocate class container\n");
 161                         continue;
 162                 }
 163
 164                 ic->cont = cont;
 165                 device_initialize(&ic->classdev);
 166                 ic->classdev.parent = get_device(dev);
 167                 ic->classdev.class = cont->class;
 168                 cont->class->dev_release = attribute_container_release;
 169                 dev_set_name(&ic->classdev, "%s", dev_name(dev));
 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         mutex_unlock(&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 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  * device_del() and then use attribute_container_device_trigger()
 203  * to do the final put on the classdev.
 204  */
 205 void
 206 attribute_container_remove_device(struct device *dev,
 207                                   void (*fn)(struct attribute_container *,
 208                                              struct device *,
 209                                              struct device *))
 210 {
 211         struct attribute_container *cont;
 212
 213         mutex_lock(&attribute_container_mutex);
 214         list_for_each_entry(cont, &attribute_container_list, node) {
 215                 struct internal_container *ic;
 216                 struct klist_iter iter;
 217
 218                 if (attribute_container_no_classdevs(cont))
 219                         continue;
 220
 221                 if (!cont->match(cont, dev))
 222                         continue;
 223
 224                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 225                         if (dev != ic->classdev.parent)
 226                                 continue;
 227                         klist_del(&ic->node);
 228                         if (fn)
 229                                 fn(cont, dev, &ic->classdev);
 230                         else {
 231                                 attribute_container_remove_attrs(&ic->classdev);
 232                                 device_unregister(&ic->classdev);
 233                         }
 234                 }
 235         }
 236         mutex_unlock(&attribute_container_mutex);
 237 }
 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 function 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 device *))
 254 {
 255         struct attribute_container *cont;
 256
 257         mutex_lock(&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.parent)
 272                                 fn(cont, dev, &ic->classdev);
 273                 }
 274         }
 275         mutex_unlock(&attribute_container_mutex);
 276 }
 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         mutex_lock(&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         mutex_unlock(&attribute_container_mutex);
 303 }
 304
 305 /**
 306  * attribute_container_add_attrs - add attributes
 307  *
 308  * @classdev: The class device
 309  *
 310  * This simply creates all the class device sysfs files from the
 311  * attributes listed in the container
 312  */
 313 int
 314 attribute_container_add_attrs(struct device *classdev)
 315 {
 316         struct attribute_container *cont =
 317                 attribute_container_classdev_to_container(classdev);
 318         struct device_attribute **attrs = cont->attrs;
 319         int i, error;
 320
 321         BUG_ON(attrs && cont->grp);
 322
 323         if (!attrs && !cont->grp)
 324                 return 0;
 325
 326         if (cont->grp)
 327                 return sysfs_create_group(&classdev->kobj, cont->grp);
 328
 329         for (i = 0; attrs[i]; i++) {
 330                 sysfs_attr_init(&attrs[i]->attr);
 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
 353         if (error)
 354                 return error;
 355         return attribute_container_add_attrs(classdev);
 356 }
 357
 358 /**
 359  * attribute_container_add_class_device_adapter - simple adapter for triggers
 360  *
 361  * This function is identical to attribute_container_add_class_device except
 362  * that it is designed to be called from the triggers
 363  */
 364 int
 365 attribute_container_add_class_device_adapter(struct attribute_container *cont,
 366                                              struct device *dev,
 367                                              struct device *classdev)
 368 {
 369         return attribute_container_add_class_device(classdev);
 370 }
 371
 372 /**
 373  * attribute_container_remove_attrs - remove any attribute files
 374  *
 375  * @classdev: The class device to remove the files from
 376  *
 377  */
 378 void
 379 attribute_container_remove_attrs(struct device *classdev)
 380 {
 381         struct attribute_container *cont =
 382                 attribute_container_classdev_to_container(classdev);
 383         struct device_attribute **attrs = cont->attrs;
 384         int i;
 385
 386         if (!attrs && !cont->grp)
 387                 return;
 388
 389         if (cont->grp) {
 390                 sysfs_remove_group(&classdev->kobj, cont->grp);
 391                 return ;
 392         }
 393
 394         for (i = 0; attrs[i]; i++)
 395                 device_remove_file(classdev, attrs[i]);
 396 }
 397
 398 /**
 399  * attribute_container_class_device_del - equivalent of class_device_del
 400  *
 401  * @classdev: the class device
 402  *
 403  * This function simply removes all the attribute files and then calls
 404  * device_del.
 405  */
 406 void
 407 attribute_container_class_device_del(struct device *classdev)
 408 {
 409         attribute_container_remove_attrs(classdev);
 410         device_del(classdev);
 411 }
 412
 413 /**
 414  * attribute_container_find_class_device - find the corresponding class_device
 415  *
 416  * @cont:       the container
 417  * @dev:        the generic device
 418  *
 419  * Looks up the device in the container's list of class devices and returns
 420  * the corresponding class_device.
 421  */
 422 struct device *
 423 attribute_container_find_class_device(struct attribute_container *cont,
 424                                       struct device *dev)
 425 {
 426         struct device *cdev = NULL;
 427         struct internal_container *ic;
 428         struct klist_iter iter;
 429
 430         klist_for_each_entry(ic, &cont->containers, node, &iter) {
 431                 if (ic->classdev.parent == dev) {
 432                         cdev = &ic->classdev;
 433                         /* FIXME: must exit iterator then break */
 434                         klist_iter_exit(&iter);
 435                         break;
 436                 }
 437         }
 438
 439         return cdev;
 440 }
 441 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);