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