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 class_private *cp = to_class(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 class_private *cp = to_class(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 class_private *cp = to_class(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 sysfs_ops class_sysfs_ops = {
  67         .show   = class_attr_show,
  68         .store  = class_attr_store,
  69 };
  70
  71 static struct kobj_type class_ktype = {
  72         .sysfs_ops      = &class_sysfs_ops,
  73         .release        = class_release,
  74 };
  75
  76 /* Hotplug events for classes go to the class class_subsys */
  77 static struct kset *class_kset;
  78
  79
  80 int class_create_file(struct class *cls, const struct class_attribute *attr)
  81 {
  82         int error;
  83         if (cls)
  84                 error = sysfs_create_file(&cls->p->class_subsys.kobj,
  85                                           &attr->attr);
  86         else
  87                 error = -EINVAL;
  88         return error;
  89 }
  90
  91 void class_remove_file(struct class *cls, const struct class_attribute *attr)
  92 {
  93         if (cls)
  94                 sysfs_remove_file(&cls->p->class_subsys.kobj, &attr->attr);
  95 }
  96
  97 static struct class *class_get(struct class *cls)
  98 {
  99         if (cls)
 100                 kset_get(&cls->p->class_subsys);
 101         return cls;
 102 }
 103
 104 static void class_put(struct class *cls)
 105 {
 106         if (cls)
 107                 kset_put(&cls->p->class_subsys);
 108 }
 109
 110 static int add_class_attrs(struct class *cls)
 111 {
 112         int i;
 113         int error = 0;
 114
 115         if (cls->class_attrs) {
 116                 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
 117                         error = class_create_file(cls, &cls->class_attrs[i]);
 118                         if (error)
 119                                 goto error;
 120                 }
 121         }
 122 done:
 123         return error;
 124 error:
 125         while (--i >= 0)
 126                 class_remove_file(cls, &cls->class_attrs[i]);
 127         goto done;
 128 }
 129
 130 static void remove_class_attrs(struct class *cls)
 131 {
 132         int i;
 133
 134         if (cls->class_attrs) {
 135                 for (i = 0; attr_name(cls->class_attrs[i]); i++)
 136                         class_remove_file(cls, &cls->class_attrs[i]);
 137         }
 138 }
 139
 140 static void klist_class_dev_get(struct klist_node *n)
 141 {
 142         struct device *dev = container_of(n, struct device, knode_class);
 143
 144         get_device(dev);
 145 }
 146
 147 static void klist_class_dev_put(struct klist_node *n)
 148 {
 149         struct device *dev = container_of(n, struct device, knode_class);
 150
 151         put_device(dev);
 152 }
 153
 154 int __class_register(struct class *cls, struct lock_class_key *key)
 155 {
 156         struct class_private *cp;
 157         int error;
 158
 159         pr_debug("device class '%s': registering\n", cls->name);
 160
 161         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 162         if (!cp)
 163                 return -ENOMEM;
 164         klist_init(&cp->class_devices, klist_class_dev_get, klist_class_dev_put);
 165         INIT_LIST_HEAD(&cp->class_interfaces);
 166         kset_init(&cp->class_dirs);
 167         __mutex_init(&cp->class_mutex, "struct class mutex", key);
 168         error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
 169         if (error) {
 170                 kfree(cp);
 171                 return error;
 172         }
 173
 174         /* set the default /sys/dev directory for devices of this class */
 175         if (!cls->dev_kobj)
 176                 cls->dev_kobj = sysfs_dev_char_kobj;
 177
 178 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
 179         /* let the block class directory show up in the root of sysfs */
 180         if (cls != &block_class)
 181                 cp->class_subsys.kobj.kset = class_kset;
 182 #else
 183         cp->class_subsys.kobj.kset = class_kset;
 184 #endif
 185         cp->class_subsys.kobj.ktype = &class_ktype;
 186         cp->class = cls;
 187         cls->p = cp;
 188
 189         error = kset_register(&cp->class_subsys);
 190         if (error) {
 191                 kfree(cp);
 192                 return error;
 193         }
 194         error = add_class_attrs(class_get(cls));
 195         class_put(cls);
 196         return error;
 197 }
 198 EXPORT_SYMBOL_GPL(__class_register);
 199
 200 void class_unregister(struct class *cls)
 201 {
 202         pr_debug("device class '%s': unregistering\n", cls->name);
 203         remove_class_attrs(cls);
 204         kset_unregister(&cls->p->class_subsys);
 205 }
 206
 207 static void class_create_release(struct class *cls)
 208 {
 209         pr_debug("%s called for %s\n", __func__, cls->name);
 210         kfree(cls);
 211 }
 212
 213 /**
 214  * class_create - create a struct class structure
 215  * @owner: pointer to the module that is to "own" this struct class
 216  * @name: pointer to a string for the name of this class.
 217  * @key: the lock_class_key for this class; used by mutex lock debugging
 218  *
 219  * This is used to create a struct class pointer that can then be used
 220  * in calls to device_create().
 221  *
 222  * Returns &struct class pointer on success, or ERR_PTR() on error.
 223  *
 224  * Note, the pointer created here is to be destroyed when finished by
 225  * making a call to class_destroy().
 226  */
 227 struct class *__class_create(struct module *owner, const char *name,
 228                              struct lock_class_key *key)
 229 {
 230         struct class *cls;
 231         int retval;
 232
 233         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 234         if (!cls) {
 235                 retval = -ENOMEM;
 236                 goto error;
 237         }
 238
 239         cls->name = name;
 240         cls->owner = owner;
 241         cls->class_release = class_create_release;
 242
 243         retval = __class_register(cls, key);
 244         if (retval)
 245                 goto error;
 246
 247         return cls;
 248
 249 error:
 250         kfree(cls);
 251         return ERR_PTR(retval);
 252 }
 253 EXPORT_SYMBOL_GPL(__class_create);
 254
 255 /**
 256  * class_destroy - destroys a struct class structure
 257  * @cls: pointer to the struct class that is to be destroyed
 258  *
 259  * Note, the pointer to be destroyed must have been created with a call
 260  * to class_create().
 261  */
 262 void class_destroy(struct class *cls)
 263 {
 264         if ((cls == NULL) || (IS_ERR(cls)))
 265                 return;
 266
 267         class_unregister(cls);
 268 }
 269
 270 #ifdef CONFIG_SYSFS_DEPRECATED
 271 char *make_class_name(const char *name, struct kobject *kobj)
 272 {
 273         char *class_name;
 274         int size;
 275
 276         size = strlen(name) + strlen(kobject_name(kobj)) + 2;
 277
 278         class_name = kmalloc(size, GFP_KERNEL);
 279         if (!class_name)
 280                 return NULL;
 281
 282         strcpy(class_name, name);
 283         strcat(class_name, ":");
 284         strcat(class_name, kobject_name(kobj));
 285         return class_name;
 286 }
 287 #endif
 288
 289 /**
 290  * class_dev_iter_init - initialize class device iterator
 291  * @iter: class iterator to initialize
 292  * @class: the class we wanna iterate over
 293  * @start: the device to start iterating from, if any
 294  * @type: device_type of the devices to iterate over, NULL for all
 295  *
 296  * Initialize class iterator @iter such that it iterates over devices
 297  * of @class.  If @start is set, the list iteration will start there,
 298  * otherwise if it is NULL, the iteration starts at the beginning of
 299  * the list.
 300  */
 301 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
 302                          struct device *start, const struct device_type *type)
 303 {
 304         struct klist_node *start_knode = NULL;
 305
 306         if (start)
 307                 start_knode = &start->knode_class;
 308         klist_iter_init_node(&class->p->class_devices, &iter->ki, start_knode);
 309         iter->type = type;
 310 }
 311 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 312
 313 /**
 314  * class_dev_iter_next - iterate to the next device
 315  * @iter: class iterator to proceed
 316  *
 317  * Proceed @iter to the next device and return it.  Returns NULL if
 318  * iteration is complete.
 319  *
 320  * The returned device is referenced and won't be released till
 321  * iterator is proceed to the next device or exited.  The caller is
 322  * free to do whatever it wants to do with the device including
 323  * calling back into class code.
 324  */
 325 struct device *class_dev_iter_next(struct class_dev_iter *iter)
 326 {
 327         struct klist_node *knode;
 328         struct device *dev;
 329
 330         while (1) {
 331                 knode = klist_next(&iter->ki);
 332                 if (!knode)
 333                         return NULL;
 334                 dev = container_of(knode, struct device, knode_class);
 335                 if (!iter->type || iter->type == dev->type)
 336                         return dev;
 337         }
 338 }
 339 EXPORT_SYMBOL_GPL(class_dev_iter_next);
 340
 341 /**
 342  * class_dev_iter_exit - finish iteration
 343  * @iter: class iterator to finish
 344  *
 345  * Finish an iteration.  Always call this function after iteration is
 346  * complete whether the iteration ran till the end or not.
 347  */
 348 void class_dev_iter_exit(struct class_dev_iter *iter)
 349 {
 350         klist_iter_exit(&iter->ki);
 351 }
 352 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 353
 354 /**
 355  * class_for_each_device - device iterator
 356  * @class: the class we're iterating
 357  * @start: the device to start with in the list, if any.
 358  * @data: data for the callback
 359  * @fn: function to be called for each device
 360  *
 361  * Iterate over @class's list of devices, and call @fn for each,
 362  * passing it @data.  If @start is set, the list iteration will start
 363  * there, otherwise if it is NULL, the iteration starts at the
 364  * beginning of the list.
 365  *
 366  * We check the return of @fn each time. If it returns anything
 367  * other than 0, we break out and return that value.
 368  *
 369  * @fn is allowed to do anything including calling back into class
 370  * code.  There's no locking restriction.
 371  */
 372 int class_for_each_device(struct class *class, struct device *start,
 373                           void *data, int (*fn)(struct device *, void *))
 374 {
 375         struct class_dev_iter iter;
 376         struct device *dev;
 377         int error = 0;
 378
 379         if (!class)
 380                 return -EINVAL;
 381         if (!class->p) {
 382                 WARN(1, "%s called for class '%s' before it was initialized",
 383                      __func__, class->name);
 384                 return -EINVAL;
 385         }
 386
 387         class_dev_iter_init(&iter, class, start, NULL);
 388         while ((dev = class_dev_iter_next(&iter))) {
 389                 error = fn(dev, data);
 390                 if (error)
 391                         break;
 392         }
 393         class_dev_iter_exit(&iter);
 394
 395         return error;
 396 }
 397 EXPORT_SYMBOL_GPL(class_for_each_device);
 398
 399 /**
 400  * class_find_device - device iterator for locating a particular device
 401  * @class: the class we're iterating
 402  * @start: Device to begin with
 403  * @data: data for the match function
 404  * @match: function to check device
 405  *
 406  * This is similar to the class_for_each_dev() function above, but it
 407  * returns a reference to a device that is 'found' for later use, as
 408  * determined by the @match callback.
 409  *
 410  * The callback should return 0 if the device doesn't match and non-zero
 411  * if it does.  If the callback returns non-zero, this function will
 412  * return to the caller and not iterate over any more devices.
 413  *
 414  * Note, you will need to drop the reference with put_device() after use.
 415  *
 416  * @fn is allowed to do anything including calling back into class
 417  * code.  There's no locking restriction.
 418  */
 419 struct device *class_find_device(struct class *class, struct device *start,
 420                                  void *data,
 421                                  int (*match)(struct device *, void *))
 422 {
 423         struct class_dev_iter iter;
 424         struct device *dev;
 425
 426         if (!class)
 427                 return NULL;
 428         if (!class->p) {
 429                 WARN(1, "%s called for class '%s' before it was initialized",
 430                      __func__, class->name);
 431                 return NULL;
 432         }
 433
 434         class_dev_iter_init(&iter, class, start, NULL);
 435         while ((dev = class_dev_iter_next(&iter))) {
 436                 if (match(dev, data)) {
 437                         get_device(dev);
 438                         break;
 439                 }
 440         }
 441         class_dev_iter_exit(&iter);
 442
 443         return dev;
 444 }
 445 EXPORT_SYMBOL_GPL(class_find_device);
 446
 447 int class_interface_register(struct class_interface *class_intf)
 448 {
 449         struct class *parent;
 450         struct class_dev_iter iter;
 451         struct device *dev;
 452
 453         if (!class_intf || !class_intf->class)
 454                 return -ENODEV;
 455
 456         parent = class_get(class_intf->class);
 457         if (!parent)
 458                 return -EINVAL;
 459
 460         mutex_lock(&parent->p->class_mutex);
 461         list_add_tail(&class_intf->node, &parent->p->class_interfaces);
 462         if (class_intf->add_dev) {
 463                 class_dev_iter_init(&iter, parent, NULL, NULL);
 464                 while ((dev = class_dev_iter_next(&iter)))
 465                         class_intf->add_dev(dev, class_intf);
 466                 class_dev_iter_exit(&iter);
 467         }
 468         mutex_unlock(&parent->p->class_mutex);
 469
 470         return 0;
 471 }
 472
 473 void class_interface_unregister(struct class_interface *class_intf)
 474 {
 475         struct class *parent = class_intf->class;
 476         struct class_dev_iter iter;
 477         struct device *dev;
 478
 479         if (!parent)
 480                 return;
 481
 482         mutex_lock(&parent->p->class_mutex);
 483         list_del_init(&class_intf->node);
 484         if (class_intf->remove_dev) {
 485                 class_dev_iter_init(&iter, parent, NULL, NULL);
 486                 while ((dev = class_dev_iter_next(&iter)))
 487                         class_intf->remove_dev(dev, class_intf);
 488                 class_dev_iter_exit(&iter);
 489         }
 490         mutex_unlock(&parent->p->class_mutex);
 491
 492         class_put(parent);
 493 }
 494
 495 ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
 496                                 char *buf)
 497 {
 498         struct class_attribute_string *cs;
 499         cs = container_of(attr, struct class_attribute_string, attr);
 500         return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
 501 }
 502
 503 EXPORT_SYMBOL_GPL(show_class_attr_string);
 504
 505 struct class_compat {
 506         struct kobject *kobj;
 507 };
 508
 509 /**
 510  * class_compat_register - register a compatibility class
 511  * @name: the name of the class
 512  *
 513  * Compatibility class are meant as a temporary user-space compatibility
 514  * workaround when converting a family of class devices to a bus devices.
 515  */
 516 struct class_compat *class_compat_register(const char *name)
 517 {
 518         struct class_compat *cls;
 519
 520         cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
 521         if (!cls)
 522                 return NULL;
 523         cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
 524         if (!cls->kobj) {
 525                 kfree(cls);
 526                 return NULL;
 527         }
 528         return cls;
 529 }
 530 EXPORT_SYMBOL_GPL(class_compat_register);
 531
 532 /**
 533  * class_compat_unregister - unregister a compatibility class
 534  * @cls: the class to unregister
 535  */
 536 void class_compat_unregister(struct class_compat *cls)
 537 {
 538         kobject_put(cls->kobj);
 539         kfree(cls);
 540 }
 541 EXPORT_SYMBOL_GPL(class_compat_unregister);
 542
 543 /**
 544  * class_compat_create_link - create a compatibility class device link to
 545  *                            a bus device
 546  * @cls: the compatibility class
 547  * @dev: the target bus device
 548  * @device_link: an optional device to which a "device" link should be created
 549  */
 550 int class_compat_create_link(struct class_compat *cls, struct device *dev,
 551                              struct device *device_link)
 552 {
 553         int error;
 554
 555         error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
 556         if (error)
 557                 return error;
 558
 559         /*
 560          * Optionally add a "device" link (typically to the parent), as a
 561          * class device would have one and we want to provide as much
 562          * backwards compatibility as possible.
 563          */
 564         if (device_link) {
 565                 error = sysfs_create_link(&dev->kobj, &device_link->kobj,
 566                                           "device");
 567                 if (error)
 568                         sysfs_remove_link(cls->kobj, dev_name(dev));
 569         }
 570
 571         return error;
 572 }
 573 EXPORT_SYMBOL_GPL(class_compat_create_link);
 574
 575 /**
 576  * class_compat_remove_link - remove a compatibility class device link to
 577  *                            a bus device
 578  * @cls: the compatibility class
 579  * @dev: the target bus device
 580  * @device_link: an optional device to which a "device" link was previously
 581  *               created
 582  */
 583 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 584                               struct device *device_link)
 585 {
 586         if (device_link)
 587                 sysfs_remove_link(&dev->kobj, "device");
 588         sysfs_remove_link(cls->kobj, dev_name(dev));
 589 }
 590 EXPORT_SYMBOL_GPL(class_compat_remove_link);
 591
 592 int __init classes_init(void)
 593 {
 594         class_kset = kset_create_and_add("class", NULL, NULL);
 595         if (!class_kset)
 596                 return -ENOMEM;
 597         return 0;
 598 }
 599
 600 EXPORT_SYMBOL_GPL(class_create_file);
 601 EXPORT_SYMBOL_GPL(class_remove_file);
 602 EXPORT_SYMBOL_GPL(class_unregister);
 603 EXPORT_SYMBOL_GPL(class_destroy);
 604
 605 EXPORT_SYMBOL_GPL(class_interface_register);
 606 EXPORT_SYMBOL_GPL(class_interface_unregister);