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