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