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 const void *class_attr_namespace(struct kobject *kobj,
  51                                         const struct attribute *attr)
  52 {
  53         struct class_attribute *class_attr = to_class_attr(attr);
  54         struct subsys_private *cp = to_subsys_private(kobj);
  55         const void *ns = NULL;
  56
  57         if (class_attr->namespace)
  58                 ns = class_attr->namespace(cp->class, class_attr);
  59         return ns;
  60 }
  61
  62 static void class_release(struct kobject *kobj)
  63 {
  64         struct subsys_private *cp = to_subsys_private(kobj);
  65         struct class *class = cp->class;
  66
  67         pr_debug("class '%s': release.\n", class->name);
  68
  69         if (class->class_release)
  70                 class->class_release(class);
  71         else
  72                 pr_debug("class '%s' does not have a release() function, "
  73                          "be careful\n", class->name);
  74
  75         kfree(cp);
  76 }
  77
  78 static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
  79 {
  80         struct subsys_private *cp = to_subsys_private(kobj);
  81         struct class *class = cp->class;
  82
  83         return class->ns_type;
  84 }
  85
  86 static const struct sysfs_ops class_sysfs_ops = {
  87         .show      = class_attr_show,
  88         .store     = class_attr_store,
  89         .namespace = class_attr_namespace,
  90 };
  91
  92 static struct kobj_type class_ktype = {
  93         .sysfs_ops      = &class_sysfs_ops,
  94         .release        = class_release,
  95         .child_ns_type  = class_child_ns_type,
  96 };
  97
  98 /* Hotplug events for classes go to the class subsys */
  99 static struct kset *class_kset;
 100
 101
 102 int class_create_file(struct class *cls, const struct class_attribute *attr)
 103 {
 104         int error;
 105         if (cls)
 106                 error = sysfs_create_file(&cls->p->subsys.kobj,
 107                                           &attr->attr);
 108         else
 109                 error = -EINVAL;
 110         return error;
 111 }
 112
 113 void class_remove_file(struct class *cls, const struct class_attribute *attr)
 114 {
 115         if (cls)
 116                 sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);
 117 }
 118
 119 static struct class *class_get(struct class *cls)
 120 {
 121         if (cls)
 122                 kset_get(&cls->p->subsys);
 123         return cls;
 124 }
 125
 126 static void class_put(struct class *cls)
 127 {
 128         if (cls)
 129                 kset_put(&cls->p->subsys);
 130 }
 131
 132 static int add_class_attrs(struct class *cls)
 133 {
 134         int i;
 135         int error = 0;
 136
 137         if (cls->class_attrs) {
 138                 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
 139                         error = class_create_file(cls, &cls->class_attrs[i]);
 140                         if (error)
 141                                 goto error;
 142                 }
 143         }
 144 done:
 145         return error;
 146 error:
 147         while (--i >= 0)
 148                 class_remove_file(cls, &cls->class_attrs[i]);
 149         goto done;
 150 }
 151
 152 static void remove_class_attrs(struct class *cls)
 153 {
 154         int i;
 155
 156         if (cls->class_attrs) {
 157                 for (i = 0; attr_name(cls->class_attrs[i]); i++)
 158                         class_remove_file(cls, &cls->class_attrs[i]);
 159         }
 160 }
 161
 162 static void klist_class_dev_get(struct klist_node *n)
 163 {
 164         struct device *dev = container_of(n, struct device, knode_class);
 165
 166         get_device(dev);
 167 }
 168
 169 static void klist_class_dev_put(struct klist_node *n)
 170 {
 171         struct device *dev = container_of(n, struct device, knode_class);
 172
 173         put_device(dev);
 174 }
 175
 176 int __class_register(struct class *cls, struct lock_class_key *key)
 177 {
 178         struct subsys_private *cp;
 179         int error;
 180
 181         pr_debug("device class '%s': registering\n", cls->name);
 182
 183         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 184         if (!cp)
 185                 return -ENOMEM;
 186         klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
 187         INIT_LIST_HEAD(&cp->interfaces);
 188         kset_init(&cp->glue_dirs);
 189         __mutex_init(&cp->mutex, "subsys mutex", key);
 190         error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
 191         if (error) {
 192                 kfree(cp);
 193                 return error;
 194         }
 195
 196         /* set the default /sys/dev directory for devices of this class */
 197         if (!cls->dev_kobj)
 198                 cls->dev_kobj = sysfs_dev_char_kobj;
 199
 200 #if defined(CONFIG_BLOCK)
 201         /* let the block class directory show up in the root of sysfs */
 202         if (!sysfs_deprecated || cls != &block_class)
 203                 cp->subsys.kobj.kset = class_kset;
 204 #else
 205         cp->subsys.kobj.kset = class_kset;
 206 #endif
 207         cp->subsys.kobj.ktype = &class_ktype;
 208         cp->class = cls;
 209         cls->p = cp;
 210
 211         error = kset_register(&cp->subsys);
 212         if (error) {
 213                 kfree(cp);
 214                 return error;
 215         }
 216         error = add_class_attrs(class_get(cls));
 217         class_put(cls);
 218         return error;
 219 }
 220 EXPORT_SYMBOL_GPL(__class_register);
 221
 222 void class_unregister(struct class *cls)
 223 {
 224         pr_debug("device class '%s': unregistering\n", cls->name);
 225         remove_class_attrs(cls);
 226         kset_unregister(&cls->p->subsys);
 227 }
 228
 229 static void class_create_release(struct class *cls)
 230 {
 231         pr_debug("%s called for %s\n", __func__, cls->name);
 232         kfree(cls);
 233 }
 234
 235 /**
 236  * class_create - create a struct class structure
 237  * @owner: pointer to the module that is to "own" this struct class
 238  * @name: pointer to a string for the name of this class.
 239  * @key: the lock_class_key for this class; used by mutex lock debugging
 240  *
 241  * This is used to create a struct class pointer that can then be used
 242  * in calls to device_create().
 243  *
 244  * Returns &struct class pointer on success, or ERR_PTR() on error.
 245  *
 246  * Note, the pointer created here is to be destroyed when finished by
 247  * making a call to class_destroy().
 248  */
 249 struct class *__class_create(struct module *owner, const char *name,
 250                              struct lock_class_key *key)
 251 {
 252         struct class *cls;
 253         int retval;
 254
 255         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 256         if (!cls) {
 257                 retval = -ENOMEM;
 258                 goto error;
 259         }
 260
 261         cls->name = name;
 262         cls->owner = owner;
 263         cls->class_release = class_create_release;
 264
 265         retval = __class_register(cls, key);
 266         if (retval)
 267                 goto error;
 268
 269         return cls;
 270
 271 error:
 272         kfree(cls);
 273         return ERR_PTR(retval);
 274 }
 275 EXPORT_SYMBOL_GPL(__class_create);
 276
 277 /**
 278  * class_destroy - destroys a struct class structure
 279  * @cls: pointer to the struct class that is to be destroyed
 280  *
 281  * Note, the pointer to be destroyed must have been created with a call
 282  * to class_create().
 283  */
 284 void class_destroy(struct class *cls)
 285 {
 286         if ((cls == NULL) || (IS_ERR(cls)))
 287                 return;
 288
 289         class_unregister(cls);
 290 }
 291
 292 /**
 293  * class_dev_iter_init - initialize class device iterator
 294  * @iter: class iterator to initialize
 295  * @class: the class we wanna iterate over
 296  * @start: the device to start iterating from, if any
 297  * @type: device_type of the devices to iterate over, NULL for all
 298  *
 299  * Initialize class iterator @iter such that it iterates over devices
 300  * of @class.  If @start is set, the list iteration will start there,
 301  * otherwise if it is NULL, the iteration starts at the beginning of
 302  * the list.
 303  */
 304 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
 305                          struct device *start, const struct device_type *type)
 306 {
 307         struct klist_node *start_knode = NULL;
 308
 309         if (start)
 310                 start_knode = &start->knode_class;
 311         klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
 312         iter->type = type;
 313 }
 314 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 315
 316 /**
 317  * class_dev_iter_next - iterate to the next device
 318  * @iter: class iterator to proceed
 319  *
 320  * Proceed @iter to the next device and return it.  Returns NULL if
 321  * iteration is complete.
 322  *
 323  * The returned device is referenced and won't be released till
 324  * iterator is proceed to the next device or exited.  The caller is
 325  * free to do whatever it wants to do with the device including
 326  * calling back into class code.
 327  */
 328 struct device *class_dev_iter_next(struct class_dev_iter *iter)
 329 {
 330         struct klist_node *knode;
 331         struct device *dev;
 332
 333         while (1) {
 334                 knode = klist_next(&iter->ki);
 335                 if (!knode)
 336                         return NULL;
 337                 dev = container_of(knode, struct device, knode_class);
 338                 if (!iter->type || iter->type == dev->type)
 339                         return dev;
 340         }
 341 }
 342 EXPORT_SYMBOL_GPL(class_dev_iter_next);
 343
 344 /**
 345  * class_dev_iter_exit - finish iteration
 346  * @iter: class iterator to finish
 347  *
 348  * Finish an iteration.  Always call this function after iteration is
 349  * complete whether the iteration ran till the end or not.
 350  */
 351 void class_dev_iter_exit(struct class_dev_iter *iter)
 352 {
 353         klist_iter_exit(&iter->ki);
 354 }
 355 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 356
 357 /**
 358  * class_for_each_device - device iterator
 359  * @class: the class we're iterating
 360  * @start: the device to start with in the list, if any.
 361  * @data: data for the callback
 362  * @fn: function to be called for each device
 363  *
 364  * Iterate over @class's list of devices, and call @fn for each,
 365  * passing it @data.  If @start is set, the list iteration will start
 366  * there, otherwise if it is NULL, the iteration starts at the
 367  * beginning of the list.
 368  *
 369  * We check the return of @fn each time. If it returns anything
 370  * other than 0, we break out and return that value.
 371  *
 372  * @fn is allowed to do anything including calling back into class
 373  * code.  There's no locking restriction.
 374  */
 375 int class_for_each_device(struct class *class, struct device *start,
 376                           void *data, int (*fn)(struct device *, void *))
 377 {
 378         struct class_dev_iter iter;
 379         struct device *dev;
 380         int error = 0;
 381
 382         if (!class)
 383                 return -EINVAL;
 384         if (!class->p) {
 385                 WARN(1, "%s called for class '%s' before it was initialized",
 386                      __func__, class->name);
 387                 return -EINVAL;
 388         }
 389
 390         class_dev_iter_init(&iter, class, start, NULL);
 391         while ((dev = class_dev_iter_next(&iter))) {
 392                 error = fn(dev, data);
 393                 if (error)
 394                         break;
 395         }
 396         class_dev_iter_exit(&iter);
 397
 398         return error;
 399 }
 400 EXPORT_SYMBOL_GPL(class_for_each_device);
 401
 402 /**
 403  * class_find_device - device iterator for locating a particular device
 404  * @class: the class we're iterating
 405  * @start: Device to begin with
 406  * @data: data for the match function
 407  * @match: function to check device
 408  *
 409  * This is similar to the class_for_each_dev() function above, but it
 410  * returns a reference to a device that is 'found' for later use, as
 411  * determined by the @match callback.
 412  *
 413  * The callback should return 0 if the device doesn't match and non-zero
 414  * if it does.  If the callback returns non-zero, this function will
 415  * return to the caller and not iterate over any more devices.
 416  *
 417  * Note, you will need to drop the reference with put_device() after use.
 418  *
 419  * @fn is allowed to do anything including calling back into class
 420  * code.  There's no locking restriction.
 421  */
 422 struct device *class_find_device(struct class *class, struct device *start,
 423                                  const void *data,
 424                                  int (*match)(struct device *, const void *))
 425 {
 426         struct class_dev_iter iter;
 427         struct device *dev;
 428
 429         if (!class)
 430                 return NULL;
 431         if (!class->p) {
 432                 WARN(1, "%s called for class '%s' before it was initialized",
 433                      __func__, class->name);
 434                 return NULL;
 435         }
 436
 437         class_dev_iter_init(&iter, class, start, NULL);
 438         while ((dev = class_dev_iter_next(&iter))) {
 439                 if (match(dev, data)) {
 440                         get_device(dev);
 441                         break;
 442                 }
 443         }
 444         class_dev_iter_exit(&iter);
 445
 446         return dev;
 447 }
 448 EXPORT_SYMBOL_GPL(class_find_device);
 449
 450 int class_interface_register(struct class_interface *class_intf)
 451 {
 452         struct class *parent;
 453         struct class_dev_iter iter;
 454         struct device *dev;
 455
 456         if (!class_intf || !class_intf->class)
 457                 return -ENODEV;
 458
 459         parent = class_get(class_intf->class);
 460         if (!parent)
 461                 return -EINVAL;
 462
 463         mutex_lock(&parent->p->mutex);
 464         list_add_tail(&class_intf->node, &parent->p->interfaces);
 465         if (class_intf->add_dev) {
 466                 class_dev_iter_init(&iter, parent, NULL, NULL);
 467                 while ((dev = class_dev_iter_next(&iter)))
 468                         class_intf->add_dev(dev, class_intf);
 469                 class_dev_iter_exit(&iter);
 470         }
 471         mutex_unlock(&parent->p->mutex);
 472
 473         return 0;
 474 }
 475
 476 void class_interface_unregister(struct class_interface *class_intf)
 477 {
 478         struct class *parent = class_intf->class;
 479         struct class_dev_iter iter;
 480         struct device *dev;
 481
 482         if (!parent)
 483                 return;
 484
 485         mutex_lock(&parent->p->mutex);
 486         list_del_init(&class_intf->node);
 487         if (class_intf->remove_dev) {
 488                 class_dev_iter_init(&iter, parent, NULL, NULL);
 489                 while ((dev = class_dev_iter_next(&iter)))
 490                         class_intf->remove_dev(dev, class_intf);
 491                 class_dev_iter_exit(&iter);
 492         }
 493         mutex_unlock(&parent->p->mutex);
 494
 495         class_put(parent);
 496 }
 497
 498 ssize_t show_class_attr_string(struct class *class,
 499                                struct class_attribute *attr, char *buf)
 500 {
 501         struct class_attribute_string *cs;
 502         cs = container_of(attr, struct class_attribute_string, attr);
 503         return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
 504 }
 505
 506 EXPORT_SYMBOL_GPL(show_class_attr_string);
 507
 508 struct class_compat {
 509         struct kobject *kobj;
 510 };
 511
 512 /**
 513  * class_compat_register - register a compatibility class
 514  * @name: the name of the class
 515  *
 516  * Compatibility class are meant as a temporary user-space compatibility
 517  * workaround when converting a family of class devices to a bus devices.
 518  */
 519 struct class_compat *class_compat_register(const char *name)
 520 {
 521         struct class_compat *cls;
 522
 523         cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
 524         if (!cls)
 525                 return NULL;
 526         cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
 527         if (!cls->kobj) {
 528                 kfree(cls);
 529                 return NULL;
 530         }
 531         return cls;
 532 }
 533 EXPORT_SYMBOL_GPL(class_compat_register);
 534
 535 /**
 536  * class_compat_unregister - unregister a compatibility class
 537  * @cls: the class to unregister
 538  */
 539 void class_compat_unregister(struct class_compat *cls)
 540 {
 541         kobject_put(cls->kobj);
 542         kfree(cls);
 543 }
 544 EXPORT_SYMBOL_GPL(class_compat_unregister);
 545
 546 /**
 547  * class_compat_create_link - create a compatibility class device link to
 548  *                            a bus device
 549  * @cls: the compatibility class
 550  * @dev: the target bus device
 551  * @device_link: an optional device to which a "device" link should be created
 552  */
 553 int class_compat_create_link(struct class_compat *cls, struct device *dev,
 554                              struct device *device_link)
 555 {
 556         int error;
 557
 558         error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
 559         if (error)
 560                 return error;
 561
 562         /*
 563          * Optionally add a "device" link (typically to the parent), as a
 564          * class device would have one and we want to provide as much
 565          * backwards compatibility as possible.
 566          */
 567         if (device_link) {
 568                 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
 569                                           "device");
 570                 if (error)
 571                         sysfs_remove_link(cls->kobj, dev_name(dev));
 572         }
 573
 574         return error;
 575 }
 576 EXPORT_SYMBOL_GPL(class_compat_create_link);
 577
 578 /**
 579  * class_compat_remove_link - remove a compatibility class device link to
 580  *                            a bus device
 581  * @cls: the compatibility class
 582  * @dev: the target bus device
 583  * @device_link: an optional device to which a "device" link was previously
 584  *               created
 585  */
 586 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 587                               struct device *device_link)
 588 {
 589         if (device_link)
 590                 sysfs_remove_link(&dev->kobj, "device");
 591         sysfs_remove_link(cls->kobj, dev_name(dev));
 592 }
 593 EXPORT_SYMBOL_GPL(class_compat_remove_link);
 594
 595 int __init classes_init(void)
 596 {
 597         class_kset = kset_create_and_add("class", NULL, NULL);
 598         if (!class_kset)
 599                 return -ENOMEM;
 600         return 0;
 601 }
 602
 603 EXPORT_SYMBOL_GPL(class_create_file);
 604 EXPORT_SYMBOL_GPL(class_remove_file);
 605 EXPORT_SYMBOL_GPL(class_unregister);
 606 EXPORT_SYMBOL_GPL(class_destroy);
 607
 608 EXPORT_SYMBOL_GPL(class_interface_register);
 609 EXPORT_SYMBOL_GPL(class_interface_unregister);