1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * bus.c - bus driver management
   4 *
   5 * Copyright (c) 2002-3 Patrick Mochel
   6 * Copyright (c) 2002-3 Open Source Development Labs
   7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   8 * Copyright (c) 2007 Novell Inc.
   9 */
  10
  11#include <linux/async.h>
  12#include <linux/device/bus.h>
  13#include <linux/device.h>
  14#include <linux/module.h>
  15#include <linux/errno.h>
  16#include <linux/slab.h>
  17#include <linux/init.h>
  18#include <linux/string.h>
  19#include <linux/mutex.h>
  20#include <linux/sysfs.h>
  21#include "base.h"
  22#include "power/power.h"
  23
  24/* /sys/devices/system */
  25static struct kset *system_kset;
  26
  27#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
  28
  29/*
  30 * sysfs bindings for drivers
  31 */
  32
  33#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
  34
  35#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
  36	struct driver_attribute driver_attr_##_name =		\
  37		__ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
  38
  39static int __must_check bus_rescan_devices_helper(struct device *dev,
  40						void *data);
  41
  42static struct bus_type *bus_get(struct bus_type *bus)
  43{
  44	if (bus) {
  45		kset_get(&bus->p->subsys);
  46		return bus;
  47	}
  48	return NULL;
  49}
  50
  51static void bus_put(struct bus_type *bus)
  52{
  53	if (bus)
  54		kset_put(&bus->p->subsys);
  55}
  56
  57static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
  58			     char *buf)
  59{
  60	struct driver_attribute *drv_attr = to_drv_attr(attr);
  61	struct driver_private *drv_priv = to_driver(kobj);
  62	ssize_t ret = -EIO;
  63
  64	if (drv_attr->show)
  65		ret = drv_attr->show(drv_priv->driver, buf);
  66	return ret;
  67}
  68
  69static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
  70			      const char *buf, size_t count)
  71{
  72	struct driver_attribute *drv_attr = to_drv_attr(attr);
  73	struct driver_private *drv_priv = to_driver(kobj);
  74	ssize_t ret = -EIO;
  75
  76	if (drv_attr->store)
  77		ret = drv_attr->store(drv_priv->driver, buf, count);
  78	return ret;
  79}
  80
  81static const struct sysfs_ops driver_sysfs_ops = {
  82	.show	= drv_attr_show,
  83	.store	= drv_attr_store,
  84};
  85
  86static void driver_release(struct kobject *kobj)
  87{
  88	struct driver_private *drv_priv = to_driver(kobj);
  89
  90	pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
  91	kfree(drv_priv);
  92}
  93
  94static struct kobj_type driver_ktype = {
  95	.sysfs_ops	= &driver_sysfs_ops,
  96	.release	= driver_release,
  97};
  98
  99/*
 100 * sysfs bindings for buses
 101 */
 102static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
 103			     char *buf)
 104{
 105	struct bus_attribute *bus_attr = to_bus_attr(attr);
 106	struct subsys_private *subsys_priv = to_subsys_private(kobj);
 107	ssize_t ret = 0;
 108
 109	if (bus_attr->show)
 110		ret = bus_attr->show(subsys_priv->bus, buf);
 111	return ret;
 112}
 113
 114static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
 115			      const char *buf, size_t count)
 116{
 117	struct bus_attribute *bus_attr = to_bus_attr(attr);
 118	struct subsys_private *subsys_priv = to_subsys_private(kobj);
 119	ssize_t ret = 0;
 120
 121	if (bus_attr->store)
 122		ret = bus_attr->store(subsys_priv->bus, buf, count);
 123	return ret;
 124}
 125
 126static const struct sysfs_ops bus_sysfs_ops = {
 127	.show	= bus_attr_show,
 128	.store	= bus_attr_store,
 129};
 130
 131int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
 132{
 133	int error;
 134	if (bus_get(bus)) {
 135		error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
 136		bus_put(bus);
 137	} else
 138		error = -EINVAL;
 139	return error;
 140}
 141EXPORT_SYMBOL_GPL(bus_create_file);
 142
 143void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
 144{
 145	if (bus_get(bus)) {
 146		sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
 147		bus_put(bus);
 148	}
 149}
 150EXPORT_SYMBOL_GPL(bus_remove_file);
 151
 152static void bus_release(struct kobject *kobj)
 153{
 154	struct subsys_private *priv = to_subsys_private(kobj);
 155	struct bus_type *bus = priv->bus;
 156
 157	kfree(priv);
 158	bus->p = NULL;
 159}
 160
 161static struct kobj_type bus_ktype = {
 162	.sysfs_ops	= &bus_sysfs_ops,
 163	.release	= bus_release,
 164};
 165
 166static int bus_uevent_filter(const struct kobject *kobj)
 167{
 168	const struct kobj_type *ktype = get_ktype(kobj);
 169
 170	if (ktype == &bus_ktype)
 171		return 1;
 172	return 0;
 173}
 174
 175static const struct kset_uevent_ops bus_uevent_ops = {
 176	.filter = bus_uevent_filter,
 177};
 178
 179static struct kset *bus_kset;
 180
 181/* Manually detach a device from its associated driver. */
 182static ssize_t unbind_store(struct device_driver *drv, const char *buf,
 183			    size_t count)
 184{
 185	struct bus_type *bus = bus_get(drv->bus);
 186	struct device *dev;
 187	int err = -ENODEV;
 188
 189	dev = bus_find_device_by_name(bus, NULL, buf);
 190	if (dev && dev->driver == drv) {
 191		device_driver_detach(dev);
 192		err = count;
 193	}
 194	put_device(dev);
 195	bus_put(bus);
 196	return err;
 197}
 198static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
 199
 200/*
 201 * Manually attach a device to a driver.
 202 * Note: the driver must want to bind to the device,
 203 * it is not possible to override the driver's id table.
 204 */
 205static ssize_t bind_store(struct device_driver *drv, const char *buf,
 206			  size_t count)
 207{
 208	struct bus_type *bus = bus_get(drv->bus);
 209	struct device *dev;
 210	int err = -ENODEV;
 211
 212	dev = bus_find_device_by_name(bus, NULL, buf);
 213	if (dev && driver_match_device(drv, dev)) {
 214		err = device_driver_attach(drv, dev);
 215		if (!err) {
 216			/* success */
 217			err = count;
 218		}
 219	}
 220	put_device(dev);
 221	bus_put(bus);
 222	return err;
 223}
 224static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
 225
 226static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
 227{
 228	return sysfs_emit(buf, "%d\n", bus->p->drivers_autoprobe);
 229}
 230
 231static ssize_t drivers_autoprobe_store(struct bus_type *bus,
 232				       const char *buf, size_t count)
 233{
 234	if (buf[0] == '0')
 235		bus->p->drivers_autoprobe = 0;
 236	else
 237		bus->p->drivers_autoprobe = 1;
 238	return count;
 239}
 240
 241static ssize_t drivers_probe_store(struct bus_type *bus,
 242				   const char *buf, size_t count)
 243{
 244	struct device *dev;
 245	int err = -EINVAL;
 246
 247	dev = bus_find_device_by_name(bus, NULL, buf);
 248	if (!dev)
 249		return -ENODEV;
 250	if (bus_rescan_devices_helper(dev, NULL) == 0)
 251		err = count;
 252	put_device(dev);
 253	return err;
 254}
 255
 256static struct device *next_device(struct klist_iter *i)
 257{
 258	struct klist_node *n = klist_next(i);
 259	struct device *dev = NULL;
 260	struct device_private *dev_prv;
 261
 262	if (n) {
 263		dev_prv = to_device_private_bus(n);
 264		dev = dev_prv->device;
 265	}
 266	return dev;
 267}
 268
 269/**
 270 * bus_for_each_dev - device iterator.
 271 * @bus: bus type.
 272 * @start: device to start iterating from.
 273 * @data: data for the callback.
 274 * @fn: function to be called for each device.
 275 *
 276 * Iterate over @bus's list of devices, and call @fn for each,
 277 * passing it @data. If @start is not NULL, we use that device to
 278 * begin iterating from.
 279 *
 280 * We check the return of @fn each time. If it returns anything
 281 * other than 0, we break out and return that value.
 282 *
 283 * NOTE: The device that returns a non-zero value is not retained
 284 * in any way, nor is its refcount incremented. If the caller needs
 285 * to retain this data, it should do so, and increment the reference
 286 * count in the supplied callback.
 287 */
 288int bus_for_each_dev(struct bus_type *bus, struct device *start,
 289		     void *data, int (*fn)(struct device *, void *))
 290{
 291	struct klist_iter i;
 292	struct device *dev;
 293	int error = 0;
 294
 295	if (!bus || !bus->p)
 296		return -EINVAL;
 297
 298	klist_iter_init_node(&bus->p->klist_devices, &i,
 299			     (start ? &start->p->knode_bus : NULL));
 300	while (!error && (dev = next_device(&i)))
 301		error = fn(dev, data);
 302	klist_iter_exit(&i);
 303	return error;
 304}
 305EXPORT_SYMBOL_GPL(bus_for_each_dev);
 306
 307/**
 308 * bus_find_device - device iterator for locating a particular device.
 309 * @bus: bus type
 310 * @start: Device to begin with
 311 * @data: Data to pass to match function
 312 * @match: Callback function to check device
 313 *
 314 * This is similar to the bus_for_each_dev() function above, but it
 315 * returns a reference to a device that is 'found' for later use, as
 316 * determined by the @match callback.
 317 *
 318 * The callback should return 0 if the device doesn't match and non-zero
 319 * if it does.  If the callback returns non-zero, this function will
 320 * return to the caller and not iterate over any more devices.
 321 */
 322struct device *bus_find_device(struct bus_type *bus,
 323			       struct device *start, const void *data,
 324			       int (*match)(struct device *dev, const void *data))
 325{
 326	struct klist_iter i;
 327	struct device *dev;
 328
 329	if (!bus || !bus->p)
 330		return NULL;
 331
 332	klist_iter_init_node(&bus->p->klist_devices, &i,
 333			     (start ? &start->p->knode_bus : NULL));
 334	while ((dev = next_device(&i)))
 335		if (match(dev, data) && get_device(dev))
 336			break;
 337	klist_iter_exit(&i);
 338	return dev;
 339}
 340EXPORT_SYMBOL_GPL(bus_find_device);
 341
 342/**
 343 * subsys_find_device_by_id - find a device with a specific enumeration number
 344 * @subsys: subsystem
 345 * @id: index 'id' in struct device
 346 * @hint: device to check first
 347 *
 348 * Check the hint's next object and if it is a match return it directly,
 349 * otherwise, fall back to a full list search. Either way a reference for
 350 * the returned object is taken.
 351 */
 352struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
 353					struct device *hint)
 354{
 355	struct klist_iter i;
 356	struct device *dev;
 357
 358	if (!subsys)
 359		return NULL;
 360
 361	if (hint) {
 362		klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
 363		dev = next_device(&i);
 364		if (dev && dev->id == id && get_device(dev)) {
 365			klist_iter_exit(&i);
 366			return dev;
 367		}
 368		klist_iter_exit(&i);
 369	}
 370
 371	klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
 372	while ((dev = next_device(&i))) {
 373		if (dev->id == id && get_device(dev)) {
 374			klist_iter_exit(&i);
 375			return dev;
 376		}
 377	}
 378	klist_iter_exit(&i);
 379	return NULL;
 380}
 381EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
 382
 383static struct device_driver *next_driver(struct klist_iter *i)
 384{
 385	struct klist_node *n = klist_next(i);
 386	struct driver_private *drv_priv;
 387
 388	if (n) {
 389		drv_priv = container_of(n, struct driver_private, knode_bus);
 390		return drv_priv->driver;
 391	}
 392	return NULL;
 393}
 394
 395/**
 396 * bus_for_each_drv - driver iterator
 397 * @bus: bus we're dealing with.
 398 * @start: driver to start iterating on.
 399 * @data: data to pass to the callback.
 400 * @fn: function to call for each driver.
 401 *
 402 * This is nearly identical to the device iterator above.
 403 * We iterate over each driver that belongs to @bus, and call
 404 * @fn for each. If @fn returns anything but 0, we break out
 405 * and return it. If @start is not NULL, we use it as the head
 406 * of the list.
 407 *
 408 * NOTE: we don't return the driver that returns a non-zero
 409 * value, nor do we leave the reference count incremented for that
 410 * driver. If the caller needs to know that info, it must set it
 411 * in the callback. It must also be sure to increment the refcount
 412 * so it doesn't disappear before returning to the caller.
 413 */
 414int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 415		     void *data, int (*fn)(struct device_driver *, void *))
 416{
 417	struct klist_iter i;
 418	struct device_driver *drv;
 419	int error = 0;
 420
 421	if (!bus)
 422		return -EINVAL;
 423
 424	klist_iter_init_node(&bus->p->klist_drivers, &i,
 425			     start ? &start->p->knode_bus : NULL);
 426	while ((drv = next_driver(&i)) && !error)
 427		error = fn(drv, data);
 428	klist_iter_exit(&i);
 429	return error;
 430}
 431EXPORT_SYMBOL_GPL(bus_for_each_drv);
 432
 433/**
 434 * bus_add_device - add device to bus
 435 * @dev: device being added
 436 *
 437 * - Add device's bus attributes.
 438 * - Create links to device's bus.
 439 * - Add the device to its bus's list of devices.
 440 */
 441int bus_add_device(struct device *dev)
 442{
 443	struct bus_type *bus = bus_get(dev->bus);
 444	int error = 0;
 445
 446	if (bus) {
 447		pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
 448		error = device_add_groups(dev, bus->dev_groups);
 449		if (error)
 450			goto out_put;
 451		error = sysfs_create_link(&bus->p->devices_kset->kobj,
 452						&dev->kobj, dev_name(dev));
 453		if (error)
 454			goto out_groups;
 455		error = sysfs_create_link(&dev->kobj,
 456				&dev->bus->p->subsys.kobj, "subsystem");
 457		if (error)
 458			goto out_subsys;
 459		klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
 460	}
 461	return 0;
 462
 463out_subsys:
 464	sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
 465out_groups:
 466	device_remove_groups(dev, bus->dev_groups);
 467out_put:
 468	bus_put(dev->bus);
 469	return error;
 470}
 471
 472/**
 473 * bus_probe_device - probe drivers for a new device
 474 * @dev: device to probe
 475 *
 476 * - Automatically probe for a driver if the bus allows it.
 477 */
 478void bus_probe_device(struct device *dev)
 479{
 480	struct bus_type *bus = dev->bus;
 481	struct subsys_interface *sif;
 482
 483	if (!bus)
 484		return;
 485
 486	if (bus->p->drivers_autoprobe)
 487		device_initial_probe(dev);
 488
 489	mutex_lock(&bus->p->mutex);
 490	list_for_each_entry(sif, &bus->p->interfaces, node)
 491		if (sif->add_dev)
 492			sif->add_dev(dev, sif);
 493	mutex_unlock(&bus->p->mutex);
 494}
 495
 496/**
 497 * bus_remove_device - remove device from bus
 498 * @dev: device to be removed
 499 *
 500 * - Remove device from all interfaces.
 501 * - Remove symlink from bus' directory.
 502 * - Delete device from bus's list.
 503 * - Detach from its driver.
 504 * - Drop reference taken in bus_add_device().
 505 */
 506void bus_remove_device(struct device *dev)
 507{
 508	struct bus_type *bus = dev->bus;
 509	struct subsys_interface *sif;
 510
 511	if (!bus)
 512		return;
 513
 514	mutex_lock(&bus->p->mutex);
 515	list_for_each_entry(sif, &bus->p->interfaces, node)
 516		if (sif->remove_dev)
 517			sif->remove_dev(dev, sif);
 518	mutex_unlock(&bus->p->mutex);
 519
 520	sysfs_remove_link(&dev->kobj, "subsystem");
 521	sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
 522			  dev_name(dev));
 523	device_remove_groups(dev, dev->bus->dev_groups);
 524	if (klist_node_attached(&dev->p->knode_bus))
 525		klist_del(&dev->p->knode_bus);
 526
 527	pr_debug("bus: '%s': remove device %s\n",
 528		 dev->bus->name, dev_name(dev));
 529	device_release_driver(dev);
 530	bus_put(dev->bus);
 531}
 532
 533static int __must_check add_bind_files(struct device_driver *drv)
 534{
 535	int ret;
 536
 537	ret = driver_create_file(drv, &driver_attr_unbind);
 538	if (ret == 0) {
 539		ret = driver_create_file(drv, &driver_attr_bind);
 540		if (ret)
 541			driver_remove_file(drv, &driver_attr_unbind);
 542	}
 543	return ret;
 544}
 545
 546static void remove_bind_files(struct device_driver *drv)
 547{
 548	driver_remove_file(drv, &driver_attr_bind);
 549	driver_remove_file(drv, &driver_attr_unbind);
 550}
 551
 552static BUS_ATTR_WO(drivers_probe);
 553static BUS_ATTR_RW(drivers_autoprobe);
 554
 555static int add_probe_files(struct bus_type *bus)
 556{
 557	int retval;
 558
 559	retval = bus_create_file(bus, &bus_attr_drivers_probe);
 560	if (retval)
 561		goto out;
 562
 563	retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
 564	if (retval)
 565		bus_remove_file(bus, &bus_attr_drivers_probe);
 566out:
 567	return retval;
 568}
 569
 570static void remove_probe_files(struct bus_type *bus)
 571{
 572	bus_remove_file(bus, &bus_attr_drivers_autoprobe);
 573	bus_remove_file(bus, &bus_attr_drivers_probe);
 574}
 575
 576static ssize_t uevent_store(struct device_driver *drv, const char *buf,
 577			    size_t count)
 578{
 579	int rc;
 580
 581	rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
 582	return rc ? rc : count;
 583}
 584static DRIVER_ATTR_WO(uevent);
 585
 586/**
 587 * bus_add_driver - Add a driver to the bus.
 588 * @drv: driver.
 589 */
 590int bus_add_driver(struct device_driver *drv)
 591{
 592	struct bus_type *bus;
 593	struct driver_private *priv;
 594	int error = 0;
 595
 596	bus = bus_get(drv->bus);
 597	if (!bus)
 598		return -EINVAL;
 599
 600	pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
 601
 602	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 603	if (!priv) {
 604		error = -ENOMEM;
 605		goto out_put_bus;
 606	}
 607	klist_init(&priv->klist_devices, NULL, NULL);
 608	priv->driver = drv;
 609	drv->p = priv;
 610	priv->kobj.kset = bus->p->drivers_kset;
 611	error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
 612				     "%s", drv->name);
 613	if (error)
 614		goto out_unregister;
 615
 616	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 617	if (drv->bus->p->drivers_autoprobe) {
 618		error = driver_attach(drv);
 619		if (error)
 620			goto out_del_list;
 621	}
 622	module_add_driver(drv->owner, drv);
 623
 624	error = driver_create_file(drv, &driver_attr_uevent);
 625	if (error) {
 626		printk(KERN_ERR "%s: uevent attr (%s) failed\n",
 627			__func__, drv->name);
 628	}
 629	error = driver_add_groups(drv, bus->drv_groups);
 630	if (error) {
 631		/* How the hell do we get out of this pickle? Give up */
 632		printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
 633			__func__, drv->name);
 634	}
 635
 636	if (!drv->suppress_bind_attrs) {
 637		error = add_bind_files(drv);
 638		if (error) {
 639			/* Ditto */
 640			printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
 641				__func__, drv->name);
 642		}
 643	}
 644
 645	return 0;
 646
 647out_del_list:
 648	klist_del(&priv->knode_bus);
 649out_unregister:
 650	kobject_put(&priv->kobj);
 651	/* drv->p is freed in driver_release()  */
 652	drv->p = NULL;
 653out_put_bus:
 654	bus_put(bus);
 655	return error;
 656}
 657
 658/**
 659 * bus_remove_driver - delete driver from bus's knowledge.
 660 * @drv: driver.
 661 *
 662 * Detach the driver from the devices it controls, and remove
 663 * it from its bus's list of drivers. Finally, we drop the reference
 664 * to the bus we took in bus_add_driver().
 665 */
 666void bus_remove_driver(struct device_driver *drv)
 667{
 668	if (!drv->bus)
 669		return;
 670
 671	if (!drv->suppress_bind_attrs)
 672		remove_bind_files(drv);
 673	driver_remove_groups(drv, drv->bus->drv_groups);
 674	driver_remove_file(drv, &driver_attr_uevent);
 675	klist_remove(&drv->p->knode_bus);
 676	pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
 677	driver_detach(drv);
 678	module_remove_driver(drv);
 679	kobject_put(&drv->p->kobj);
 680	bus_put(drv->bus);
 681}
 682
 683/* Helper for bus_rescan_devices's iter */
 684static int __must_check bus_rescan_devices_helper(struct device *dev,
 685						  void *data)
 686{
 687	int ret = 0;
 688
 689	if (!dev->driver) {
 690		if (dev->parent && dev->bus->need_parent_lock)
 691			device_lock(dev->parent);
 692		ret = device_attach(dev);
 693		if (dev->parent && dev->bus->need_parent_lock)
 694			device_unlock(dev->parent);
 695	}
 696	return ret < 0 ? ret : 0;
 697}
 698
 699/**
 700 * bus_rescan_devices - rescan devices on the bus for possible drivers
 701 * @bus: the bus to scan.
 702 *
 703 * This function will look for devices on the bus with no driver
 704 * attached and rescan it against existing drivers to see if it matches
 705 * any by calling device_attach() for the unbound devices.
 706 */
 707int bus_rescan_devices(struct bus_type *bus)
 708{
 709	return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
 710}
 711EXPORT_SYMBOL_GPL(bus_rescan_devices);
 712
 713/**
 714 * device_reprobe - remove driver for a device and probe for a new driver
 715 * @dev: the device to reprobe
 716 *
 717 * This function detaches the attached driver (if any) for the given
 718 * device and restarts the driver probing process.  It is intended
 719 * to use if probing criteria changed during a devices lifetime and
 720 * driver attachment should change accordingly.
 721 */
 722int device_reprobe(struct device *dev)
 723{
 724	if (dev->driver)
 725		device_driver_detach(dev);
 726	return bus_rescan_devices_helper(dev, NULL);
 727}
 728EXPORT_SYMBOL_GPL(device_reprobe);
 729
 730static int bus_add_groups(struct bus_type *bus,
 731			  const struct attribute_group **groups)
 732{
 733	return sysfs_create_groups(&bus->p->subsys.kobj, groups);
 734}
 735
 736static void bus_remove_groups(struct bus_type *bus,
 737			      const struct attribute_group **groups)
 738{
 739	sysfs_remove_groups(&bus->p->subsys.kobj, groups);
 740}
 741
 742static void klist_devices_get(struct klist_node *n)
 743{
 744	struct device_private *dev_prv = to_device_private_bus(n);
 745	struct device *dev = dev_prv->device;
 746
 747	get_device(dev);
 748}
 749
 750static void klist_devices_put(struct klist_node *n)
 751{
 752	struct device_private *dev_prv = to_device_private_bus(n);
 753	struct device *dev = dev_prv->device;
 754
 755	put_device(dev);
 756}
 757
 758static ssize_t bus_uevent_store(struct bus_type *bus,
 759				const char *buf, size_t count)
 760{
 761	int rc;
 762
 763	rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
 764	return rc ? rc : count;
 765}
 766/*
 767 * "open code" the old BUS_ATTR() macro here.  We want to use BUS_ATTR_WO()
 768 * here, but can not use it as earlier in the file we have
 769 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
 770 * function name.
 771 */
 772static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
 773						     bus_uevent_store);
 774
 775/**
 776 * bus_register - register a driver-core subsystem
 777 * @bus: bus to register
 778 *
 779 * Once we have that, we register the bus with the kobject
 780 * infrastructure, then register the children subsystems it has:
 781 * the devices and drivers that belong to the subsystem.
 782 */
 783int bus_register(struct bus_type *bus)
 784{
 785	int retval;
 786	struct subsys_private *priv;
 787	struct lock_class_key *key = &bus->lock_key;
 788
 789	priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
 790	if (!priv)
 791		return -ENOMEM;
 792
 793	priv->bus = bus;
 794	bus->p = priv;
 795
 796	BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 797
 798	retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 799	if (retval)
 800		goto out;
 801
 802	priv->subsys.kobj.kset = bus_kset;
 803	priv->subsys.kobj.ktype = &bus_ktype;
 804	priv->drivers_autoprobe = 1;
 805
 806	retval = kset_register(&priv->subsys);
 807	if (retval)
 808		goto out;
 809
 810	retval = bus_create_file(bus, &bus_attr_uevent);
 811	if (retval)
 812		goto bus_uevent_fail;
 813
 814	priv->devices_kset = kset_create_and_add("devices", NULL,
 815						 &priv->subsys.kobj);
 816	if (!priv->devices_kset) {
 817		retval = -ENOMEM;
 818		goto bus_devices_fail;
 819	}
 820
 821	priv->drivers_kset = kset_create_and_add("drivers", NULL,
 822						 &priv->subsys.kobj);
 823	if (!priv->drivers_kset) {
 824		retval = -ENOMEM;
 825		goto bus_drivers_fail;
 826	}
 827
 828	INIT_LIST_HEAD(&priv->interfaces);
 829	__mutex_init(&priv->mutex, "subsys mutex", key);
 830	klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
 831	klist_init(&priv->klist_drivers, NULL, NULL);
 832
 833	retval = add_probe_files(bus);
 834	if (retval)
 835		goto bus_probe_files_fail;
 836
 837	retval = bus_add_groups(bus, bus->bus_groups);
 838	if (retval)
 839		goto bus_groups_fail;
 840
 841	pr_debug("bus: '%s': registered\n", bus->name);
 842	return 0;
 843
 844bus_groups_fail:
 845	remove_probe_files(bus);
 846bus_probe_files_fail:
 847	kset_unregister(bus->p->drivers_kset);
 848bus_drivers_fail:
 849	kset_unregister(bus->p->devices_kset);
 850bus_devices_fail:
 851	bus_remove_file(bus, &bus_attr_uevent);
 852bus_uevent_fail:
 853	kset_unregister(&bus->p->subsys);
 854out:
 855	kfree(bus->p);
 856	bus->p = NULL;
 857	return retval;
 858}
 859EXPORT_SYMBOL_GPL(bus_register);
 860
 861/**
 862 * bus_unregister - remove a bus from the system
 863 * @bus: bus.
 864 *
 865 * Unregister the child subsystems and the bus itself.
 866 * Finally, we call bus_put() to release the refcount
 867 */
 868void bus_unregister(struct bus_type *bus)
 869{
 870	pr_debug("bus: '%s': unregistering\n", bus->name);
 871	if (bus->dev_root)
 872		device_unregister(bus->dev_root);
 873	bus_remove_groups(bus, bus->bus_groups);
 874	remove_probe_files(bus);
 875	kset_unregister(bus->p->drivers_kset);
 876	kset_unregister(bus->p->devices_kset);
 877	bus_remove_file(bus, &bus_attr_uevent);
 878	kset_unregister(&bus->p->subsys);
 879}
 880EXPORT_SYMBOL_GPL(bus_unregister);
 881
 882int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 883{
 884	return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 885}
 886EXPORT_SYMBOL_GPL(bus_register_notifier);
 887
 888int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 889{
 890	return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 891}
 892EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 893
 894struct kset *bus_get_kset(struct bus_type *bus)
 895{
 896	return &bus->p->subsys;
 897}
 898EXPORT_SYMBOL_GPL(bus_get_kset);
 899
 900struct klist *bus_get_device_klist(struct bus_type *bus)
 901{
 902	return &bus->p->klist_devices;
 903}
 904EXPORT_SYMBOL_GPL(bus_get_device_klist);
 905
 906/*
 907 * Yes, this forcibly breaks the klist abstraction temporarily.  It
 908 * just wants to sort the klist, not change reference counts and
 909 * take/drop locks rapidly in the process.  It does all this while
 910 * holding the lock for the list, so objects can't otherwise be
 911 * added/removed while we're swizzling.
 912 */
 913static void device_insertion_sort_klist(struct device *a, struct list_head *list,
 914					int (*compare)(const struct device *a,
 915							const struct device *b))
 916{
 917	struct klist_node *n;
 918	struct device_private *dev_prv;
 919	struct device *b;
 920
 921	list_for_each_entry(n, list, n_node) {
 922		dev_prv = to_device_private_bus(n);
 923		b = dev_prv->device;
 924		if (compare(a, b) <= 0) {
 925			list_move_tail(&a->p->knode_bus.n_node,
 926				       &b->p->knode_bus.n_node);
 927			return;
 928		}
 929	}
 930	list_move_tail(&a->p->knode_bus.n_node, list);
 931}
 932
 933void bus_sort_breadthfirst(struct bus_type *bus,
 934			   int (*compare)(const struct device *a,
 935					  const struct device *b))
 936{
 937	LIST_HEAD(sorted_devices);
 938	struct klist_node *n, *tmp;
 939	struct device_private *dev_prv;
 940	struct device *dev;
 941	struct klist *device_klist;
 942
 943	device_klist = bus_get_device_klist(bus);
 944
 945	spin_lock(&device_klist->k_lock);
 946	list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
 947		dev_prv = to_device_private_bus(n);
 948		dev = dev_prv->device;
 949		device_insertion_sort_klist(dev, &sorted_devices, compare);
 950	}
 951	list_splice(&sorted_devices, &device_klist->k_list);
 952	spin_unlock(&device_klist->k_lock);
 953}
 954EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
 955
 956/**
 957 * subsys_dev_iter_init - initialize subsys device iterator
 958 * @iter: subsys iterator to initialize
 959 * @subsys: the subsys we wanna iterate over
 960 * @start: the device to start iterating from, if any
 961 * @type: device_type of the devices to iterate over, NULL for all
 962 *
 963 * Initialize subsys iterator @iter such that it iterates over devices
 964 * of @subsys.  If @start is set, the list iteration will start there,
 965 * otherwise if it is NULL, the iteration starts at the beginning of
 966 * the list.
 967 */
 968void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
 969			  struct device *start, const struct device_type *type)
 970{
 971	struct klist_node *start_knode = NULL;
 972
 973	if (start)
 974		start_knode = &start->p->knode_bus;
 975	klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
 976	iter->type = type;
 977}
 978EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
 979
 980/**
 981 * subsys_dev_iter_next - iterate to the next device
 982 * @iter: subsys iterator to proceed
 983 *
 984 * Proceed @iter to the next device and return it.  Returns NULL if
 985 * iteration is complete.
 986 *
 987 * The returned device is referenced and won't be released till
 988 * iterator is proceed to the next device or exited.  The caller is
 989 * free to do whatever it wants to do with the device including
 990 * calling back into subsys code.
 991 */
 992struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
 993{
 994	struct klist_node *knode;
 995	struct device *dev;
 996
 997	for (;;) {
 998		knode = klist_next(&iter->ki);
 999		if (!knode)
1000			return NULL;
1001		dev = to_device_private_bus(knode)->device;
1002		if (!iter->type || iter->type == dev->type)
1003			return dev;
1004	}
1005}
1006EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
1007
1008/**
1009 * subsys_dev_iter_exit - finish iteration
1010 * @iter: subsys iterator to finish
1011 *
1012 * Finish an iteration.  Always call this function after iteration is
1013 * complete whether the iteration ran till the end or not.
1014 */
1015void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
1016{
1017	klist_iter_exit(&iter->ki);
1018}
1019EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
1020
1021int subsys_interface_register(struct subsys_interface *sif)
1022{
1023	struct bus_type *subsys;
1024	struct subsys_dev_iter iter;
1025	struct device *dev;
1026
1027	if (!sif || !sif->subsys)
1028		return -ENODEV;
1029
1030	subsys = bus_get(sif->subsys);
1031	if (!subsys)
1032		return -EINVAL;
1033
1034	mutex_lock(&subsys->p->mutex);
1035	list_add_tail(&sif->node, &subsys->p->interfaces);
1036	if (sif->add_dev) {
1037		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1038		while ((dev = subsys_dev_iter_next(&iter)))
1039			sif->add_dev(dev, sif);
1040		subsys_dev_iter_exit(&iter);
1041	}
1042	mutex_unlock(&subsys->p->mutex);
1043
1044	return 0;
1045}
1046EXPORT_SYMBOL_GPL(subsys_interface_register);
1047
1048void subsys_interface_unregister(struct subsys_interface *sif)
1049{
1050	struct bus_type *subsys;
1051	struct subsys_dev_iter iter;
1052	struct device *dev;
1053
1054	if (!sif || !sif->subsys)
1055		return;
1056
1057	subsys = sif->subsys;
1058
1059	mutex_lock(&subsys->p->mutex);
1060	list_del_init(&sif->node);
1061	if (sif->remove_dev) {
1062		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
1063		while ((dev = subsys_dev_iter_next(&iter)))
1064			sif->remove_dev(dev, sif);
1065		subsys_dev_iter_exit(&iter);
1066	}
1067	mutex_unlock(&subsys->p->mutex);
1068
1069	bus_put(subsys);
1070}
1071EXPORT_SYMBOL_GPL(subsys_interface_unregister);
1072
1073static void system_root_device_release(struct device *dev)
1074{
1075	kfree(dev);
1076}
1077
1078static int subsys_register(struct bus_type *subsys,
1079			   const struct attribute_group **groups,
1080			   struct kobject *parent_of_root)
1081{
1082	struct device *dev;
1083	int err;
1084
1085	err = bus_register(subsys);
1086	if (err < 0)
1087		return err;
1088
1089	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
1090	if (!dev) {
1091		err = -ENOMEM;
1092		goto err_dev;
1093	}
1094
1095	err = dev_set_name(dev, "%s", subsys->name);
1096	if (err < 0)
1097		goto err_name;
1098
1099	dev->kobj.parent = parent_of_root;
1100	dev->groups = groups;
1101	dev->release = system_root_device_release;
1102
1103	err = device_register(dev);
1104	if (err < 0)
1105		goto err_dev_reg;
1106
1107	subsys->dev_root = dev;
1108	return 0;
1109
1110err_dev_reg:
1111	put_device(dev);
1112	dev = NULL;
1113err_name:
1114	kfree(dev);
1115err_dev:
1116	bus_unregister(subsys);
1117	return err;
1118}
1119
1120/**
1121 * subsys_system_register - register a subsystem at /sys/devices/system/
1122 * @subsys: system subsystem
1123 * @groups: default attributes for the root device
1124 *
1125 * All 'system' subsystems have a /sys/devices/system/<name> root device
1126 * with the name of the subsystem. The root device can carry subsystem-
1127 * wide attributes. All registered devices are below this single root
1128 * device and are named after the subsystem with a simple enumeration
1129 * number appended. The registered devices are not explicitly named;
1130 * only 'id' in the device needs to be set.
1131 *
1132 * Do not use this interface for anything new, it exists for compatibility
1133 * with bad ideas only. New subsystems should use plain subsystems; and
1134 * add the subsystem-wide attributes should be added to the subsystem
1135 * directory itself and not some create fake root-device placed in
1136 * /sys/devices/system/<name>.
1137 */
1138int subsys_system_register(struct bus_type *subsys,
1139			   const struct attribute_group **groups)
1140{
1141	return subsys_register(subsys, groups, &system_kset->kobj);
1142}
1143EXPORT_SYMBOL_GPL(subsys_system_register);
1144
1145/**
1146 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
1147 * @subsys: virtual subsystem
1148 * @groups: default attributes for the root device
1149 *
1150 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
1151 * with the name of the subystem.  The root device can carry subsystem-wide
1152 * attributes.  All registered devices are below this single root device.
1153 * There's no restriction on device naming.  This is for kernel software
1154 * constructs which need sysfs interface.
1155 */
1156int subsys_virtual_register(struct bus_type *subsys,
1157			    const struct attribute_group **groups)
1158{
1159	struct kobject *virtual_dir;
1160
1161	virtual_dir = virtual_device_parent(NULL);
1162	if (!virtual_dir)
1163		return -ENOMEM;
1164
1165	return subsys_register(subsys, groups, virtual_dir);
1166}
1167EXPORT_SYMBOL_GPL(subsys_virtual_register);
1168
1169int __init buses_init(void)
1170{
1171	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
1172	if (!bus_kset)
1173		return -ENOMEM;
1174
1175	system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
1176	if (!system_kset)
1177		return -ENOMEM;
1178
1179	return 0;
1180}