drivers/base/class.c

   1 /*
   2  * class.c - basic device class management
   3  *
   4  * Copyright (c) 2002-3 Patrick Mochel
   5  * Copyright (c) 2002-3 Open Source Development Labs
   6  * Copyright (c) 2003-2004 Greg Kroah-Hartman
   7  * Copyright (c) 2003-2004 IBM Corp.
   8  *
   9  * This file is released under the GPLv2
  10  *
  11  */
  12
  13 #include <linux/device.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/string.h>
  17 #include <linux/kdev_t.h>
  18 #include <linux/err.h>
  19 #include <linux/slab.h>
  20 #include <linux/genhd.h>
  21 #include <linux/mutex.h>
  22 #include "base.h"
  23
  24 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
  25
  26 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
  27                                char *buf)
  28 {
  29         struct class_attribute *class_attr = to_class_attr(attr);
  30         struct subsys_private *cp = to_subsys_private(kobj);
  31         ssize_t ret = -EIO;
  32
  33         if (class_attr->show)
  34                 ret = class_attr->show(cp->class, class_attr, buf);
  35         return ret;
  36 }
  37
  38 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
  39                                 const char *buf, size_t count)
  40 {
  41         struct class_attribute *class_attr = to_class_attr(attr);
  42         struct subsys_private *cp = to_subsys_private(kobj);
  43         ssize_t ret = -EIO;
  44
  45         if (class_attr->store)
  46                 ret = class_attr->store(cp->class, class_attr, buf, count);
  47         return ret;
  48 }
  49
  50 static void class_release(struct kobject *kobj)
  51 {
  52         struct subsys_private *cp = to_subsys_private(kobj);
  53         struct class *class = cp->class;
  54
  55         pr_debug("class '%s': release.\n", class->name);
  56
  57         if (class->class_release)
  58                 class->class_release(class);
  59         else
  60                 pr_debug("class '%s' does not have a release() function, "
  61                          "be careful\n", class->name);
  62
  63         kfree(cp);
  64 }
  65
  66 static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
  67 {
  68         struct subsys_private *cp = to_subsys_private(kobj);
  69         struct class *class = cp->class;
  70
  71         return class->ns_type;
  72 }
  73
  74 static const struct sysfs_ops class_sysfs_ops = {
  75         .show   = class_attr_show,
  76         .store  = class_attr_store,
  77 };
  78
  79 static struct kobj_type class_ktype = {
  80         .sysfs_ops      = &class_sysfs_ops,
  81         .release        = class_release,
  82         .child_ns_type  = class_child_ns_type,
  83 };
  84
  85 /* Hotplug events for classes go to the class subsys */
  86 static struct kset *class_kset;
  87
  88
  89 int class_create_file(struct class *cls, const struct class_attribute *attr)
  90 {
  91         int error;
  92         if (cls)
  93                 error = sysfs_create_file(&cls->p->subsys.kobj,
  94                                           &attr->attr);
  95         else
  96                 error = -EINVAL;
  97         return error;
  98 }
  99
 100 void class_remove_file(struct class *cls, const struct class_attribute *attr)
 101 {
 102         if (cls)
 103                 sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);
 104 }
 105
 106 static struct class *class_get(struct class *cls)
 107 {
 108         if (cls)
 109                 kset_get(&cls->p->subsys);
 110         return cls;
 111 }
 112
 113 static void class_put(struct class *cls)
 114 {
 115         if (cls)
 116                 kset_put(&cls->p->subsys);
 117 }
 118
 119 static int add_class_attrs(struct class *cls)
 120 {
 121         int i;
 122         int error = 0;
 123
 124         if (cls->class_attrs) {
 125                 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
 126                         error = class_create_file(cls, &cls->class_attrs[i]);
 127                         if (error)
 128                                 goto error;
 129                 }
 130         }
 131 done:
 132         return error;
 133 error:
 134         while (--i >= 0)
 135                 class_remove_file(cls, &cls->class_attrs[i]);
 136         goto done;
 137 }
 138
 139 static void remove_class_attrs(struct class *cls)
 140 {
 141         int i;
 142
 143         if (cls->class_attrs) {
 144                 for (i = 0; attr_name(cls->class_attrs[i]); i++)
 145                         class_remove_file(cls, &cls->class_attrs[i]);
 146         }
 147 }
 148
 149 static void klist_class_dev_get(struct klist_node *n)
 150 {
 151         struct device *dev = container_of(n, struct device, knode_class);
 152
 153         get_device(dev);
 154 }
 155
 156 static void klist_class_dev_put(struct klist_node *n)
 157 {
 158         struct device *dev = container_of(n, struct device, knode_class);
 159
 160         put_device(dev);
 161 }
 162
 163 int __class_register(struct class *cls, struct lock_class_key *key)
 164 {
 165         struct subsys_private *cp;
 166         int error;
 167
 168         pr_debug("device class '%s': registering\n", cls->name);
 169
 170         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 171         if (!cp)
 172                 return -ENOMEM;
 173         klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
 174         INIT_LIST_HEAD(&cp->class_interfaces);
 175         kset_init(&cp->glue_dirs);
 176         __mutex_init(&cp->class_mutex, "struct class mutex", key);
 177         error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
 178         if (error) {
 179                 kfree(cp);
 180                 return error;
 181         }
 182
 183         /* set the default /sys/dev directory for devices of this class */
 184         if (!cls->dev_kobj)
 185                 cls->dev_kobj = sysfs_dev_char_kobj;
 186
 187 #if defined(CONFIG_BLOCK)
 188         /* let the block class directory show up in the root of sysfs */
 189         if (!sysfs_deprecated || cls != &block_class)
 190                 cp->subsys.kobj.kset = class_kset;
 191 #else
 192         cp->subsys.kobj.kset = class_kset;
 193 #endif
 194         cp->subsys.kobj.ktype = &class_ktype;
 195         cp->class = cls;
 196         cls->p = cp;
 197
 198         error = kset_register(&cp->subsys);
 199         if (error) {
 200                 kfree(cp);
 201                 return error;
 202         }
 203         error = add_class_attrs(class_get(cls));
 204         class_put(cls);
 205         return error;
 206 }
 207 EXPORT_SYMBOL_GPL(__class_register);
 208
 209 void class_unregister(struct class *cls)
 210 {
 211         pr_debug("device class '%s': unregistering\n", cls->name);
 212         remove_class_attrs(cls);
 213         kset_unregister(&cls->p->subsys);
 214 }
 215
 216 static void class_create_release(struct class *cls)
 217 {
 218         pr_debug("%s called for %s\n", __func__, cls->name);
 219         kfree(cls);
 220 }
 221
 222 /**
 223  * class_create - create a struct class structure
 224  * @owner: pointer to the module that is to "own" this struct class
 225  * @name: pointer to a string for the name of this class.
 226  * @key: the lock_class_key for this class; used by mutex lock debugging
 227  *
 228  * This is used to create a struct class pointer that can then be used
 229  * in calls to device_create().
 230  *
 231  * Returns &struct class pointer on success, or ERR_PTR() on error.
 232  *
 233  * Note, the pointer created here is to be destroyed when finished by
 234  * making a call to class_destroy().
 235  */
 236 struct class *__class_create(struct module *owner, const char *name,
 237                              struct lock_class_key *key)
 238 {
 239         struct class *cls;
 240         int retval;
 241
 242         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 243         if (!cls) {
 244                 retval = -ENOMEM;
 245                 goto error;
 246         }
 247
 248         cls->name = name;
 249         cls->owner = owner;
 250         cls->class_release = class_create_release;
 251
 252         retval = __class_register(cls, key);
 253         if (retval)
 254                 goto error;
 255
 256         return cls;
 257
 258 error:
 259         kfree(cls);
 260         return ERR_PTR(retval);
 261 }
 262 EXPORT_SYMBOL_GPL(__class_create);
 263
 264 /**
 265  * class_destroy - destroys a struct class structure
 266  * @cls: pointer to the struct class that is to be destroyed
 267  *
 268  * Note, the pointer to be destroyed must have been created with a call
 269  * to class_create().
 270  */
 271 void class_destroy(struct class *cls)
 272 {
 273         if ((cls == NULL) || (IS_ERR(cls)))
 274                 return;
 275
 276         class_unregister(cls);
 277 }
 278
 279 /**
 280  * class_dev_iter_init - initialize class device iterator
 281  * @iter: class iterator to initialize
 282  * @class: the class we wanna iterate over
 283  * @start: the device to start iterating from, if any
 284  * @type: device_type of the devices to iterate over, NULL for all
 285  *
 286  * Initialize class iterator @iter such that it iterates over devices
 287  * of @class.  If @start is set, the list iteration will start there,
 288  * otherwise if it is NULL, the iteration starts at the beginning of
 289  * the list.
 290  */
 291 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
 292                          struct device *start, const struct device_type *type)
 293 {
 294         struct klist_node *start_knode = NULL;
 295
 296         if (start)
 297                 start_knode = &start->knode_class;
 298         klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
 299         iter->type = type;
 300 }
 301 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 302
 303 /**
 304  * class_dev_iter_next - iterate to the next device
 305  * @iter: class iterator to proceed
 306  *
 307  * Proceed @iter to the next device and return it.  Returns NULL if
 308  * iteration is complete.
 309  *
 310  * The returned device is referenced and won't be released till
 311  * iterator is proceed to the next device or exited.  The caller is
 312  * free to do whatever it wants to do with the device including
 313  * calling back into class code.
 314  */
 315 struct device *class_dev_iter_next(struct class_dev_iter *iter)
 316 {
 317         struct klist_node *knode;
 318         struct device *dev;
 319
 320         while (1) {
 321                 knode = klist_next(&iter->ki);
 322                 if (!knode)
 323                         return NULL;
 324                 dev = container_of(knode, struct device, knode_class);
 325                 if (!iter->type || iter->type == dev->type)
 326                         return dev;
 327         }
 328 }
 329 EXPORT_SYMBOL_GPL(class_dev_iter_next);
 330
 331 /**
 332  * class_dev_iter_exit - finish iteration
 333  * @iter: class iterator to finish
 334  *
 335  * Finish an iteration.  Always call this function after iteration is
 336  * complete whether the iteration ran till the end or not.
 337  */
 338 void class_dev_iter_exit(struct class_dev_iter *iter)
 339 {
 340         klist_iter_exit(&iter->ki);
 341 }
 342 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 343
 344 /**
 345  * class_for_each_device - device iterator
 346  * @class: the class we're iterating
 347  * @start: the device to start with in the list, if any.
 348  * @data: data for the callback
 349  * @fn: function to be called for each device
 350  *
 351  * Iterate over @class's list of devices, and call @fn for each,
 352  * passing it @data.  If @start is set, the list iteration will start
 353  * there, otherwise if it is NULL, the iteration starts at the
 354  * beginning of the list.
 355  *
 356  * We check the return of @fn each time. If it returns anything
 357  * other than 0, we break out and return that value.
 358  *
 359  * @fn is allowed to do anything including calling back into class
 360  * code.  There's no locking restriction.
 361  */
 362 int class_for_each_device(struct class *class, struct device *start,
 363                           void *data, int (*fn)(struct device *, void *))
 364 {
 365         struct class_dev_iter iter;
 366         struct device *dev;
 367         int error = 0;
 368
 369         if (!class)
 370                 return -EINVAL;
 371         if (!class->p) {
 372                 WARN(1, "%s called for class '%s' before it was initialized",
 373                      __func__, class->name);
 374                 return -EINVAL;
 375         }
 376
 377         class_dev_iter_init(&iter, class, start, NULL);
 378         while ((dev = class_dev_iter_next(&iter))) {
 379                 error = fn(dev, data);
 380                 if (error)
 381                         break;
 382         }
 383         class_dev_iter_exit(&iter);
 384
 385         return error;
 386 }
 387 EXPORT_SYMBOL_GPL(class_for_each_device);
 388
 389 /**
 390  * class_find_device - device iterator for locating a particular device
 391  * @class: the class we're iterating
 392  * @start: Device to begin with
 393  * @data: data for the match function
 394  * @match: function to check device
 395  *
 396  * This is similar to the class_for_each_dev() function above, but it
 397  * returns a reference to a device that is 'found' for later use, as
 398  * determined by the @match callback.
 399  *
 400  * The callback should return 0 if the device doesn't match and non-zero
 401  * if it does.  If the callback returns non-zero, this function will
 402  * return to the caller and not iterate over any more devices.
 403  *
 404  * Note, you will need to drop the reference with put_device() after use.
 405  *
 406  * @fn is allowed to do anything including calling back into class
 407  * code.  There's no locking restriction.
 408  */
 409 struct device *class_find_device(struct class *class, struct device *start,
 410                                  void *data,
 411                                  int (*match)(struct device *, void *))
 412 {
 413         struct class_dev_iter iter;
 414         struct device *dev;
 415
 416         if (!class)
 417                 return NULL;
 418         if (!class->p) {
 419                 WARN(1, "%s called for class '%s' before it was initialized",
 420                      __func__, class->name);
 421                 return NULL;
 422         }
 423
 424         class_dev_iter_init(&iter, class, start, NULL);
 425         while ((dev = class_dev_iter_next(&iter))) {
 426                 if (match(dev, data)) {
 427                         get_device(dev);
 428                         break;
 429                 }
 430         }
 431         class_dev_iter_exit(&iter);
 432
 433         return dev;
 434 }
 435 EXPORT_SYMBOL_GPL(class_find_device);
 436
 437 int class_interface_register(struct class_interface *class_intf)
 438 {
 439         struct class *parent;
 440         struct class_dev_iter iter;
 441         struct device *dev;
 442
 443         if (!class_intf || !class_intf->class)
 444                 return -ENODEV;
 445
 446         parent = class_get(class_intf->class);
 447         if (!parent)
 448                 return -EINVAL;
 449
 450         mutex_lock(&parent->p->class_mutex);
 451         list_add_tail(&class_intf->node, &parent->p->class_interfaces);
 452         if (class_intf->add_dev) {
 453                 class_dev_iter_init(&iter, parent, NULL, NULL);
 454                 while ((dev = class_dev_iter_next(&iter)))
 455                         class_intf->add_dev(dev, class_intf);
 456                 class_dev_iter_exit(&iter);
 457         }
 458         mutex_unlock(&parent->p->class_mutex);
 459
 460         return 0;
 461 }
 462
 463 void class_interface_unregister(struct class_interface *class_intf)
 464 {
 465         struct class *parent = class_intf->class;
 466         struct class_dev_iter iter;
 467         struct device *dev;
 468
 469         if (!parent)
 470                 return;
 471
 472         mutex_lock(&parent->p->class_mutex);
 473         list_del_init(&class_intf->node);
 474         if (class_intf->remove_dev) {
 475                 class_dev_iter_init(&iter, parent, NULL, NULL);
 476                 while ((dev = class_dev_iter_next(&iter)))
 477                         class_intf->remove_dev(dev, class_intf);
 478                 class_dev_iter_exit(&iter);
 479         }
 480         mutex_unlock(&parent->p->class_mutex);
 481
 482         class_put(parent);
 483 }
 484
 485 ssize_t show_class_attr_string(struct class *class,
 486                                struct class_attribute *attr, char *buf)
 487 {
 488         struct class_attribute_string *cs;
 489         cs = container_of(attr, struct class_attribute_string, attr);
 490         return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
 491 }
 492
 493 EXPORT_SYMBOL_GPL(show_class_attr_string);
 494
 495 struct class_compat {
 496         struct kobject *kobj;
 497 };
 498
 499 /**
 500  * class_compat_register - register a compatibility class
 501  * @name: the name of the class
 502  *
 503  * Compatibility class are meant as a temporary user-space compatibility
 504  * workaround when converting a family of class devices to a bus devices.
 505  */
 506 struct class_compat *class_compat_register(const char *name)
 507 {
 508         struct class_compat *cls;
 509
 510         cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
 511         if (!cls)
 512                 return NULL;
 513         cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
 514         if (!cls->kobj) {
 515                 kfree(cls);
 516                 return NULL;
 517         }
 518         return cls;
 519 }
 520 EXPORT_SYMBOL_GPL(class_compat_register);
 521
 522 /**
 523  * class_compat_unregister - unregister a compatibility class
 524  * @cls: the class to unregister
 525  */
 526 void class_compat_unregister(struct class_compat *cls)
 527 {
 528         kobject_put(cls->kobj);
 529         kfree(cls);
 530 }
 531 EXPORT_SYMBOL_GPL(class_compat_unregister);
 532
 533 /**
 534  * class_compat_create_link - create a compatibility class device link to
 535  *                            a bus device
 536  * @cls: the compatibility class
 537  * @dev: the target bus device
 538  * @device_link: an optional device to which a "device" link should be created
 539  */
 540 int class_compat_create_link(struct class_compat *cls, struct device *dev,
 541                              struct device *device_link)
 542 {
 543         int error;
 544
 545         error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
 546         if (error)
 547                 return error;
 548
 549         /*
 550          * Optionally add a "device" link (typically to the parent), as a
 551          * class device would have one and we want to provide as much
 552          * backwards compatibility as possible.
 553          */
 554         if (device_link) {
 555                 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
 556                                           "device");
 557                 if (error)
 558                         sysfs_remove_link(cls->kobj, dev_name(dev));
 559         }
 560
 561         return error;
 562 }
 563 EXPORT_SYMBOL_GPL(class_compat_create_link);
 564
 565 /**
 566  * class_compat_remove_link - remove a compatibility class device link to
 567  *                            a bus device
 568  * @cls: the compatibility class
 569  * @dev: the target bus device
 570  * @device_link: an optional device to which a "device" link was previously
 571  *               created
 572  */
 573 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 574                               struct device *device_link)
 575 {
 576         if (device_link)
 577                 sysfs_remove_link(&dev->kobj, "device");
 578         sysfs_remove_link(cls->kobj, dev_name(dev));
 579 }
 580 EXPORT_SYMBOL_GPL(class_compat_remove_link);
 581
 582 int __init classes_init(void)
 583 {
 584         class_kset = kset_create_and_add("class", NULL, NULL);
 585         if (!class_kset)
 586                 return -ENOMEM;
 587         return 0;
 588 }
 589
 590 EXPORT_SYMBOL_GPL(class_create_file);
 591 EXPORT_SYMBOL_GPL(class_remove_file);
 592 EXPORT_SYMBOL_GPL(class_unregister);
 593 EXPORT_SYMBOL_GPL(class_destroy);
 594
 595 EXPORT_SYMBOL_GPL(class_interface_register);
 596 EXPORT_SYMBOL_GPL(class_interface_unregister);