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 /**
  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         klist_init(&cont->containers);
  61
  62         down(&attribute_container_mutex);
  63         list_add_tail(&cont->node, &attribute_container_list);
  64         up(&attribute_container_mutex);
  65
  66         return 0;
  67 }
  68 EXPORT_SYMBOL_GPL(attribute_container_register);
  69
  70 /**
  71  * attribute_container_unregister - remove a container registration
  72  *
  73  * @cont: previously registered container to remove
  74  */
  75 int
  76 attribute_container_unregister(struct attribute_container *cont)
  77 {
  78         int retval = -EBUSY;
  79         down(&attribute_container_mutex);
  80         spin_lock(&cont->containers.k_lock);
  81         if (!list_empty(&cont->containers.k_list))
  82                 goto out;
  83         retval = 0;
  84         list_del(&cont->node);
  85  out:
  86         spin_unlock(&cont->containers.k_lock);
  87         up(&attribute_container_mutex);
  88         return retval;
  89
  90 }
  91 EXPORT_SYMBOL_GPL(attribute_container_unregister);
  92
  93 /* private function used as class release */
  94 static void attribute_container_release(struct class_device *classdev)
  95 {
  96         struct internal_container *ic
  97                 = container_of(classdev, struct internal_container, classdev);
  98         struct device *dev = classdev->dev;
  99
 100         kfree(ic);
 101         put_device(dev);
 102 }
 103
 104 /**
 105  * attribute_container_add_device - see if any container is interested in dev
 106  *
 107  * @dev: device to add attributes to
 108  * @fn:  function to trigger addition of class device.
 109  *
 110  * This function allocates storage for the class device(s) to be
 111  * attached to dev (one for each matching attribute_container).  If no
 112  * fn is provided, the code will simply register the class device via
 113  * class_device_add.  If a function is provided, it is expected to add
 114  * the class device at the appropriate time.  One of the things that
 115  * might be necessary is to allocate and initialise the classdev and
 116  * then add it a later time.  To do this, call this routine for
 117  * allocation and initialisation and then use
 118  * attribute_container_device_trigger() to call class_device_add() on
 119  * it.  Note: after this, the class device contains a reference to dev
 120  * which is not relinquished until the release of the classdev.
 121  */
 122 void
 123 attribute_container_add_device(struct device *dev,
 124                                int (*fn)(struct attribute_container *,
 125                                          struct device *,
 126                                          struct class_device *))
 127 {
 128         struct attribute_container *cont;
 129
 130         down(&attribute_container_mutex);
 131         list_for_each_entry(cont, &attribute_container_list, node) {
 132                 struct internal_container *ic;
 133
 134                 if (attribute_container_no_classdevs(cont))
 135                         continue;
 136
 137                 if (!cont->match(cont, dev))
 138                         continue;
 139                 ic = kmalloc(sizeof(struct internal_container), GFP_KERNEL);
 140                 if (!ic) {
 141                         dev_printk(KERN_ERR, dev, "failed to allocate class container\n");
 142                         continue;
 143                 }
 144                 memset(ic, 0, sizeof(struct internal_container));
 145                 ic->cont = cont;
 146                 class_device_initialize(&ic->classdev);
 147                 ic->classdev.dev = get_device(dev);
 148                 ic->classdev.class = cont->class;
 149                 cont->class->release = attribute_container_release;
 150                 strcpy(ic->classdev.class_id, dev->bus_id);
 151                 if (fn)
 152                         fn(cont, dev, &ic->classdev);
 153                 else
 154                         attribute_container_add_class_device(&ic->classdev);
 155                 klist_add_tail(&ic->node, &cont->containers);
 156         }
 157         up(&attribute_container_mutex);
 158 }
 159
 160 /* FIXME: can't break out of this unless klist_iter_exit is also
 161  * called before doing the break
 162  */
 163 #define klist_for_each_entry(pos, head, member, iter) \
 164         for (klist_iter_init(head, iter); (pos = ({ \
 165                 struct klist_node *n = klist_next(iter); \
 166                 n ? ({ klist_iter_exit(iter) ; NULL; }) : \
 167                         container_of(n, typeof(*pos), member);\
 168         }) ) != NULL; )
 169
 170
 171 /**
 172  * attribute_container_remove_device - make device eligible for removal.
 173  *
 174  * @dev:  The generic device
 175  * @fn:   A function to call to remove the device
 176  *
 177  * This routine triggers device removal.  If fn is NULL, then it is
 178  * simply done via class_device_unregister (note that if something
 179  * still has a reference to the classdev, then the memory occupied
 180  * will not be freed until the classdev is released).  If you want a
 181  * two phase release: remove from visibility and then delete the
 182  * device, then you should use this routine with a fn that calls
 183  * class_device_del() and then use
 184  * attribute_container_device_trigger() to do the final put on the
 185  * classdev.
 186  */
 187 void
 188 attribute_container_remove_device(struct device *dev,
 189                                   void (*fn)(struct attribute_container *,
 190                                              struct device *,
 191                                              struct class_device *))
 192 {
 193         struct attribute_container *cont;
 194
 195         down(&attribute_container_mutex);
 196         list_for_each_entry(cont, &attribute_container_list, node) {
 197                 struct internal_container *ic;
 198                 struct klist_iter iter;
 199
 200                 if (attribute_container_no_classdevs(cont))
 201                         continue;
 202
 203                 if (!cont->match(cont, dev))
 204                         continue;
 205
 206                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 207                         if (dev != ic->classdev.dev)
 208                                 continue;
 209                         klist_remove(&ic->node);
 210                         if (fn)
 211                                 fn(cont, dev, &ic->classdev);
 212                         else {
 213                                 attribute_container_remove_attrs(&ic->classdev);
 214                                 class_device_unregister(&ic->classdev);
 215                         }
 216                 }
 217         }
 218         up(&attribute_container_mutex);
 219 }
 220 EXPORT_SYMBOL_GPL(attribute_container_remove_device);
 221
 222 /**
 223  * attribute_container_device_trigger - execute a trigger for each matching classdev
 224  *
 225  * @dev:  The generic device to run the trigger for
 226  * @fn    the function to execute for each classdev.
 227  *
 228  * This funcion is for executing a trigger when you need to know both
 229  * the container and the classdev.  If you only care about the
 230  * container, then use attribute_container_trigger() instead.
 231  */
 232 void
 233 attribute_container_device_trigger(struct device *dev,
 234                                    int (*fn)(struct attribute_container *,
 235                                              struct device *,
 236                                              struct class_device *))
 237 {
 238         struct attribute_container *cont;
 239
 240         down(&attribute_container_mutex);
 241         list_for_each_entry(cont, &attribute_container_list, node) {
 242                 struct internal_container *ic;
 243                 struct klist_iter iter;
 244
 245                 if (!cont->match(cont, dev))
 246                         continue;
 247
 248                 if (attribute_container_no_classdevs(cont)) {
 249                         fn(cont, dev, NULL);
 250                         continue;
 251                 }
 252
 253                 klist_for_each_entry(ic, &cont->containers, node, &iter) {
 254                         if (dev == ic->classdev.dev)
 255                                 fn(cont, dev, &ic->classdev);
 256                 }
 257         }
 258         up(&attribute_container_mutex);
 259 }
 260 EXPORT_SYMBOL_GPL(attribute_container_device_trigger);
 261
 262 /**
 263  * attribute_container_trigger - trigger a function for each matching container
 264  *
 265  * @dev:  The generic device to activate the trigger for
 266  * @fn:   the function to trigger
 267  *
 268  * This routine triggers a function that only needs to know the
 269  * matching containers (not the classdev) associated with a device.
 270  * It is more lightweight than attribute_container_device_trigger, so
 271  * should be used in preference unless the triggering function
 272  * actually needs to know the classdev.
 273  */
 274 void
 275 attribute_container_trigger(struct device *dev,
 276                             int (*fn)(struct attribute_container *,
 277                                       struct device *))
 278 {
 279         struct attribute_container *cont;
 280
 281         down(&attribute_container_mutex);
 282         list_for_each_entry(cont, &attribute_container_list, node) {
 283                 if (cont->match(cont, dev))
 284                         fn(cont, dev);
 285         }
 286         up(&attribute_container_mutex);
 287 }
 288 EXPORT_SYMBOL_GPL(attribute_container_trigger);
 289
 290 /**
 291  * attribute_container_add_attrs - add attributes
 292  *
 293  * @classdev: The class device
 294  *
 295  * This simply creates all the class device sysfs files from the
 296  * attributes listed in the container
 297  */
 298 int
 299 attribute_container_add_attrs(struct class_device *classdev)
 300 {
 301         struct attribute_container *cont =
 302                 attribute_container_classdev_to_container(classdev);
 303         struct class_device_attribute **attrs = cont->attrs;
 304         int i, error;
 305
 306         if (!attrs)
 307                 return 0;
 308
 309         for (i = 0; attrs[i]; i++) {
 310                 error = class_device_create_file(classdev, attrs[i]);
 311                 if (error)
 312                         return error;
 313         }
 314
 315         return 0;
 316 }
 317 EXPORT_SYMBOL_GPL(attribute_container_add_attrs);
 318
 319 /**
 320  * attribute_container_add_class_device - same function as class_device_add
 321  *
 322  * @classdev:   the class device to add
 323  *
 324  * This performs essentially the same function as class_device_add except for
 325  * attribute containers, namely add the classdev to the system and then
 326  * create the attribute files
 327  */
 328 int
 329 attribute_container_add_class_device(struct class_device *classdev)
 330 {
 331         int error = class_device_add(classdev);
 332         if (error)
 333                 return error;
 334         return attribute_container_add_attrs(classdev);
 335 }
 336 EXPORT_SYMBOL_GPL(attribute_container_add_class_device);
 337
 338 /**
 339  * attribute_container_add_class_device_adapter - simple adapter for triggers
 340  *
 341  * This function is identical to attribute_container_add_class_device except
 342  * that it is designed to be called from the triggers
 343  */
 344 int
 345 attribute_container_add_class_device_adapter(struct attribute_container *cont,
 346                                              struct device *dev,
 347                                              struct class_device *classdev)
 348 {
 349         return attribute_container_add_class_device(classdev);
 350 }
 351 EXPORT_SYMBOL_GPL(attribute_container_add_class_device_adapter);
 352
 353 /**
 354  * attribute_container_remove_attrs - remove any attribute files
 355  *
 356  * @classdev: The class device to remove the files from
 357  *
 358  */
 359 void
 360 attribute_container_remove_attrs(struct class_device *classdev)
 361 {
 362         struct attribute_container *cont =
 363                 attribute_container_classdev_to_container(classdev);
 364         struct class_device_attribute **attrs = cont->attrs;
 365         int i;
 366
 367         if (!attrs)
 368                 return;
 369
 370         for (i = 0; attrs[i]; i++)
 371                 class_device_remove_file(classdev, attrs[i]);
 372 }
 373 EXPORT_SYMBOL_GPL(attribute_container_remove_attrs);
 374
 375 /**
 376  * attribute_container_class_device_del - equivalent of class_device_del
 377  *
 378  * @classdev: the class device
 379  *
 380  * This function simply removes all the attribute files and then calls
 381  * class_device_del.
 382  */
 383 void
 384 attribute_container_class_device_del(struct class_device *classdev)
 385 {
 386         attribute_container_remove_attrs(classdev);
 387         class_device_del(classdev);
 388 }
 389 EXPORT_SYMBOL_GPL(attribute_container_class_device_del);
 390
 391 /**
 392  * attribute_container_find_class_device - find the corresponding class_device
 393  *
 394  * @cont:       the container
 395  * @dev:        the generic device
 396  *
 397  * Looks up the device in the container's list of class devices and returns
 398  * the corresponding class_device.
 399  */
 400 struct class_device *
 401 attribute_container_find_class_device(struct attribute_container *cont,
 402                                       struct device *dev)
 403 {
 404         struct class_device *cdev = NULL;
 405         struct internal_container *ic;
 406         struct klist_iter iter;
 407
 408         klist_for_each_entry(ic, &cont->containers, node, &iter) {
 409                 if (ic->classdev.dev == dev) {
 410                         cdev = &ic->classdev;
 411                         /* FIXME: must exit iterator then break */
 412                         klist_iter_exit(&iter);
 413                         break;
 414                 }
 415         }
 416
 417         return cdev;
 418 }
 419 EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
 420
 421 int __init
 422 attribute_container_init(void)
 423 {
 424         INIT_LIST_HEAD(&attribute_container_list);
 425         return 0;
 426 }