core.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * drivers/base/core.c - core driver model code (device registration, etc)
   4 *
   5 * Copyright (c) 2002-3 Patrick Mochel
   6 * Copyright (c) 2002-3 Open Source Development Labs
   7 * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
   8 * Copyright (c) 2006 Novell, Inc.
   9 */
  10
  11#include <linux/acpi.h>
  12#include <linux/blkdev.h>
  13#include <linux/cleanup.h>
  14#include <linux/cpufreq.h>
  15#include <linux/device.h>
  16#include <linux/dma-map-ops.h> /* for dma_default_coherent */
  17#include <linux/err.h>
  18#include <linux/fwnode.h>
  19#include <linux/init.h>
  20#include <linux/kdev_t.h>
  21#include <linux/kstrtox.h>
  22#include <linux/module.h>
  23#include <linux/mutex.h>
  24#include <linux/netdevice.h>
  25#include <linux/notifier.h>
  26#include <linux/of.h>
  27#include <linux/of_device.h>
  28#include <linux/pm_runtime.h>
  29#include <linux/sched/mm.h>
  30#include <linux/sched/signal.h>
  31#include <linux/slab.h>
  32#include <linux/string_helpers.h>
  33#include <linux/swiotlb.h>
  34#include <linux/sysfs.h>
  35
  36#include "base.h"
  37#include "physical_location.h"
  38#include "power/power.h"
  39
  40/* Device links support. */
  41static LIST_HEAD(deferred_sync);
  42static unsigned int defer_sync_state_count = 1;
  43static DEFINE_MUTEX(fwnode_link_lock);
  44static bool fw_devlink_is_permissive(void);
  45static void __fw_devlink_link_to_consumers(struct device *dev);
  46static bool fw_devlink_drv_reg_done;
  47static bool fw_devlink_best_effort;
  48static struct workqueue_struct *device_link_wq;
  49
  50/**
  51 * __fwnode_link_add - Create a link between two fwnode_handles.
  52 * @con: Consumer end of the link.
  53 * @sup: Supplier end of the link.
  54 * @flags: Link flags.
  55 *
  56 * Create a fwnode link between fwnode handles @con and @sup. The fwnode link
  57 * represents the detail that the firmware lists @sup fwnode as supplying a
  58 * resource to @con.
  59 *
  60 * The driver core will use the fwnode link to create a device link between the
  61 * two device objects corresponding to @con and @sup when they are created. The
  62 * driver core will automatically delete the fwnode link between @con and @sup
  63 * after doing that.
  64 *
  65 * Attempts to create duplicate links between the same pair of fwnode handles
  66 * are ignored and there is no reference counting.
  67 */
  68static int __fwnode_link_add(struct fwnode_handle *con,
  69			     struct fwnode_handle *sup, u8 flags)
  70{
  71	struct fwnode_link *link;
  72
  73	list_for_each_entry(link, &sup->consumers, s_hook)
  74		if (link->consumer == con) {
  75			link->flags |= flags;
  76			return 0;
  77		}
  78
  79	link = kzalloc(sizeof(*link), GFP_KERNEL);
  80	if (!link)
  81		return -ENOMEM;
  82
  83	link->supplier = sup;
  84	INIT_LIST_HEAD(&link->s_hook);
  85	link->consumer = con;
  86	INIT_LIST_HEAD(&link->c_hook);
  87	link->flags = flags;
  88
  89	list_add(&link->s_hook, &sup->consumers);
  90	list_add(&link->c_hook, &con->suppliers);
  91	pr_debug("%pfwf Linked as a fwnode consumer to %pfwf\n",
  92		 con, sup);
  93
  94	return 0;
  95}
  96
  97int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup,
  98		    u8 flags)
  99{
 100	guard(mutex)(&fwnode_link_lock);
 101
 102	return __fwnode_link_add(con, sup, flags);
 103}
 104
 105/**
 106 * __fwnode_link_del - Delete a link between two fwnode_handles.
 107 * @link: the fwnode_link to be deleted
 108 *
 109 * The fwnode_link_lock needs to be held when this function is called.
 110 */
 111static void __fwnode_link_del(struct fwnode_link *link)
 112{
 113	pr_debug("%pfwf Dropping the fwnode link to %pfwf\n",
 114		 link->consumer, link->supplier);
 115	list_del(&link->s_hook);
 116	list_del(&link->c_hook);
 117	kfree(link);
 118}
 119
 120/**
 121 * __fwnode_link_cycle - Mark a fwnode link as being part of a cycle.
 122 * @link: the fwnode_link to be marked
 123 *
 124 * The fwnode_link_lock needs to be held when this function is called.
 125 */
 126static void __fwnode_link_cycle(struct fwnode_link *link)
 127{
 128	pr_debug("%pfwf: cycle: depends on %pfwf\n",
 129		 link->consumer, link->supplier);
 130	link->flags |= FWLINK_FLAG_CYCLE;
 131}
 132
 133/**
 134 * fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.
 135 * @fwnode: fwnode whose supplier links need to be deleted
 136 *
 137 * Deletes all supplier links connecting directly to @fwnode.
 138 */
 139static void fwnode_links_purge_suppliers(struct fwnode_handle *fwnode)
 140{
 141	struct fwnode_link *link, *tmp;
 142
 143	guard(mutex)(&fwnode_link_lock);
 144
 145	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook)
 146		__fwnode_link_del(link);
 147}
 148
 149/**
 150 * fwnode_links_purge_consumers - Delete all consumer links of fwnode_handle.
 151 * @fwnode: fwnode whose consumer links need to be deleted
 152 *
 153 * Deletes all consumer links connecting directly to @fwnode.
 154 */
 155static void fwnode_links_purge_consumers(struct fwnode_handle *fwnode)
 156{
 157	struct fwnode_link *link, *tmp;
 158
 159	guard(mutex)(&fwnode_link_lock);
 160
 161	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook)
 162		__fwnode_link_del(link);
 163}
 164
 165/**
 166 * fwnode_links_purge - Delete all links connected to a fwnode_handle.
 167 * @fwnode: fwnode whose links needs to be deleted
 168 *
 169 * Deletes all links connecting directly to a fwnode.
 170 */
 171void fwnode_links_purge(struct fwnode_handle *fwnode)
 172{
 173	fwnode_links_purge_suppliers(fwnode);
 174	fwnode_links_purge_consumers(fwnode);
 175}
 176
 177void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode)
 178{
 179	struct fwnode_handle *child;
 180
 181	/* Don't purge consumer links of an added child */
 182	if (fwnode->dev)
 183		return;
 184
 185	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
 186	fwnode_links_purge_consumers(fwnode);
 187
 188	fwnode_for_each_available_child_node(fwnode, child)
 189		fw_devlink_purge_absent_suppliers(child);
 190}
 191EXPORT_SYMBOL_GPL(fw_devlink_purge_absent_suppliers);
 192
 193/**
 194 * __fwnode_links_move_consumers - Move consumer from @from to @to fwnode_handle
 195 * @from: move consumers away from this fwnode
 196 * @to: move consumers to this fwnode
 197 *
 198 * Move all consumer links from @from fwnode to @to fwnode.
 199 */
 200static void __fwnode_links_move_consumers(struct fwnode_handle *from,
 201					  struct fwnode_handle *to)
 202{
 203	struct fwnode_link *link, *tmp;
 204
 205	list_for_each_entry_safe(link, tmp, &from->consumers, s_hook) {
 206		__fwnode_link_add(link->consumer, to, link->flags);
 207		__fwnode_link_del(link);
 208	}
 209}
 210
 211/**
 212 * __fw_devlink_pickup_dangling_consumers - Pick up dangling consumers
 213 * @fwnode: fwnode from which to pick up dangling consumers
 214 * @new_sup: fwnode of new supplier
 215 *
 216 * If the @fwnode has a corresponding struct device and the device supports
 217 * probing (that is, added to a bus), then we want to let fw_devlink create
 218 * MANAGED device links to this device, so leave @fwnode and its descendant's
 219 * fwnode links alone.
 220 *
 221 * Otherwise, move its consumers to the new supplier @new_sup.
 222 */
 223static void __fw_devlink_pickup_dangling_consumers(struct fwnode_handle *fwnode,
 224						   struct fwnode_handle *new_sup)
 225{
 226	struct fwnode_handle *child;
 227
 228	if (fwnode->dev && fwnode->dev->bus)
 229		return;
 230
 231	fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
 232	__fwnode_links_move_consumers(fwnode, new_sup);
 233
 234	fwnode_for_each_available_child_node(fwnode, child)
 235		__fw_devlink_pickup_dangling_consumers(child, new_sup);
 236}
 237
 238static DEFINE_MUTEX(device_links_lock);
 239DEFINE_STATIC_SRCU(device_links_srcu);
 240
 241static inline void device_links_write_lock(void)
 242{
 243	mutex_lock(&device_links_lock);
 244}
 245
 246static inline void device_links_write_unlock(void)
 247{
 248	mutex_unlock(&device_links_lock);
 249}
 250
 251int device_links_read_lock(void) __acquires(&device_links_srcu)
 252{
 253	return srcu_read_lock(&device_links_srcu);
 254}
 255
 256void device_links_read_unlock(int idx) __releases(&device_links_srcu)
 257{
 258	srcu_read_unlock(&device_links_srcu, idx);
 259}
 260
 261int device_links_read_lock_held(void)
 262{
 263	return srcu_read_lock_held(&device_links_srcu);
 264}
 265
 266static void device_link_synchronize_removal(void)
 267{
 268	synchronize_srcu(&device_links_srcu);
 269}
 270
 271static void device_link_remove_from_lists(struct device_link *link)
 272{
 273	list_del_rcu(&link->s_node);
 274	list_del_rcu(&link->c_node);
 275}
 276
 277static bool device_is_ancestor(struct device *dev, struct device *target)
 278{
 279	while (target->parent) {
 280		target = target->parent;
 281		if (dev == target)
 282			return true;
 283	}
 284	return false;
 285}
 286
 287#define DL_MARKER_FLAGS		(DL_FLAG_INFERRED | \
 288				 DL_FLAG_CYCLE | \
 289				 DL_FLAG_MANAGED)
 290bool device_link_flag_is_sync_state_only(u32 flags)
 291{
 292	return (flags & ~DL_MARKER_FLAGS) == DL_FLAG_SYNC_STATE_ONLY;
 293}
 294
 295/**
 296 * device_is_dependent - Check if one device depends on another one
 297 * @dev: Device to check dependencies for.
 298 * @target: Device to check against.
 299 *
 300 * Check if @target depends on @dev or any device dependent on it (its child or
 301 * its consumer etc).  Return 1 if that is the case or 0 otherwise.
 302 */
 303static int device_is_dependent(struct device *dev, void *target)
 304{
 305	struct device_link *link;
 306	int ret;
 307
 308	/*
 309	 * The "ancestors" check is needed to catch the case when the target
 310	 * device has not been completely initialized yet and it is still
 311	 * missing from the list of children of its parent device.
 312	 */
 313	if (dev == target || device_is_ancestor(dev, target))
 314		return 1;
 315
 316	ret = device_for_each_child(dev, target, device_is_dependent);
 317	if (ret)
 318		return ret;
 319
 320	list_for_each_entry(link, &dev->links.consumers, s_node) {
 321		if (device_link_flag_is_sync_state_only(link->flags))
 322			continue;
 323
 324		if (link->consumer == target)
 325			return 1;
 326
 327		ret = device_is_dependent(link->consumer, target);
 328		if (ret)
 329			break;
 330	}
 331	return ret;
 332}
 333
 334static void device_link_init_status(struct device_link *link,
 335				    struct device *consumer,
 336				    struct device *supplier)
 337{
 338	switch (supplier->links.status) {
 339	case DL_DEV_PROBING:
 340		switch (consumer->links.status) {
 341		case DL_DEV_PROBING:
 342			/*
 343			 * A consumer driver can create a link to a supplier
 344			 * that has not completed its probing yet as long as it
 345			 * knows that the supplier is already functional (for
 346			 * example, it has just acquired some resources from the
 347			 * supplier).
 348			 */
 349			link->status = DL_STATE_CONSUMER_PROBE;
 350			break;
 351		default:
 352			link->status = DL_STATE_DORMANT;
 353			break;
 354		}
 355		break;
 356	case DL_DEV_DRIVER_BOUND:
 357		switch (consumer->links.status) {
 358		case DL_DEV_PROBING:
 359			link->status = DL_STATE_CONSUMER_PROBE;
 360			break;
 361		case DL_DEV_DRIVER_BOUND:
 362			link->status = DL_STATE_ACTIVE;
 363			break;
 364		default:
 365			link->status = DL_STATE_AVAILABLE;
 366			break;
 367		}
 368		break;
 369	case DL_DEV_UNBINDING:
 370		link->status = DL_STATE_SUPPLIER_UNBIND;
 371		break;
 372	default:
 373		link->status = DL_STATE_DORMANT;
 374		break;
 375	}
 376}
 377
 378static int device_reorder_to_tail(struct device *dev, void *not_used)
 379{
 380	struct device_link *link;
 381
 382	/*
 383	 * Devices that have not been registered yet will be put to the ends
 384	 * of the lists during the registration, so skip them here.
 385	 */
 386	if (device_is_registered(dev))
 387		devices_kset_move_last(dev);
 388
 389	if (device_pm_initialized(dev))
 390		device_pm_move_last(dev);
 391
 392	device_for_each_child(dev, NULL, device_reorder_to_tail);
 393	list_for_each_entry(link, &dev->links.consumers, s_node) {
 394		if (device_link_flag_is_sync_state_only(link->flags))
 395			continue;
 396		device_reorder_to_tail(link->consumer, NULL);
 397	}
 398
 399	return 0;
 400}
 401
 402/**
 403 * device_pm_move_to_tail - Move set of devices to the end of device lists
 404 * @dev: Device to move
 405 *
 406 * This is a device_reorder_to_tail() wrapper taking the requisite locks.
 407 *
 408 * It moves the @dev along with all of its children and all of its consumers
 409 * to the ends of the device_kset and dpm_list, recursively.
 410 */
 411void device_pm_move_to_tail(struct device *dev)
 412{
 413	int idx;
 414
 415	idx = device_links_read_lock();
 416	device_pm_lock();
 417	device_reorder_to_tail(dev, NULL);
 418	device_pm_unlock();
 419	device_links_read_unlock(idx);
 420}
 421
 422#define to_devlink(dev)	container_of((dev), struct device_link, link_dev)
 423
 424static ssize_t status_show(struct device *dev,
 425			   struct device_attribute *attr, char *buf)
 426{
 427	const char *output;
 428
 429	switch (to_devlink(dev)->status) {
 430	case DL_STATE_NONE:
 431		output = "not tracked";
 432		break;
 433	case DL_STATE_DORMANT:
 434		output = "dormant";
 435		break;
 436	case DL_STATE_AVAILABLE:
 437		output = "available";
 438		break;
 439	case DL_STATE_CONSUMER_PROBE:
 440		output = "consumer probing";
 441		break;
 442	case DL_STATE_ACTIVE:
 443		output = "active";
 444		break;
 445	case DL_STATE_SUPPLIER_UNBIND:
 446		output = "supplier unbinding";
 447		break;
 448	default:
 449		output = "unknown";
 450		break;
 451	}
 452
 453	return sysfs_emit(buf, "%s\n", output);
 454}
 455static DEVICE_ATTR_RO(status);
 456
 457static ssize_t auto_remove_on_show(struct device *dev,
 458				   struct device_attribute *attr, char *buf)
 459{
 460	struct device_link *link = to_devlink(dev);
 461	const char *output;
 462
 463	if (device_link_test(link, DL_FLAG_AUTOREMOVE_SUPPLIER))
 464		output = "supplier unbind";
 465	else if (device_link_test(link, DL_FLAG_AUTOREMOVE_CONSUMER))
 466		output = "consumer unbind";
 467	else
 468		output = "never";
 469
 470	return sysfs_emit(buf, "%s\n", output);
 471}
 472static DEVICE_ATTR_RO(auto_remove_on);
 473
 474static ssize_t runtime_pm_show(struct device *dev,
 475			       struct device_attribute *attr, char *buf)
 476{
 477	struct device_link *link = to_devlink(dev);
 478
 479	return sysfs_emit(buf, "%d\n", device_link_test(link, DL_FLAG_PM_RUNTIME));
 480}
 481static DEVICE_ATTR_RO(runtime_pm);
 482
 483static ssize_t sync_state_only_show(struct device *dev,
 484				    struct device_attribute *attr, char *buf)
 485{
 486	struct device_link *link = to_devlink(dev);
 487
 488	return sysfs_emit(buf, "%d\n", device_link_test(link, DL_FLAG_SYNC_STATE_ONLY));
 489}
 490static DEVICE_ATTR_RO(sync_state_only);
 491
 492static struct attribute *devlink_attrs[] = {
 493	&dev_attr_status.attr,
 494	&dev_attr_auto_remove_on.attr,
 495	&dev_attr_runtime_pm.attr,
 496	&dev_attr_sync_state_only.attr,
 497	NULL,
 498};
 499ATTRIBUTE_GROUPS(devlink);
 500
 501static void device_link_release_fn(struct work_struct *work)
 502{
 503	struct device_link *link = container_of(work, struct device_link, rm_work);
 504
 505	/* Ensure that all references to the link object have been dropped. */
 506	device_link_synchronize_removal();
 507
 508	pm_runtime_release_supplier(link);
 509	/*
 510	 * If supplier_preactivated is set, the link has been dropped between
 511	 * the pm_runtime_get_suppliers() and pm_runtime_put_suppliers() calls
 512	 * in __driver_probe_device().  In that case, drop the supplier's
 513	 * PM-runtime usage counter to remove the reference taken by
 514	 * pm_runtime_get_suppliers().
 515	 */
 516	if (link->supplier_preactivated)
 517		pm_runtime_put_noidle(link->supplier);
 518
 519	pm_request_idle(link->supplier);
 520
 521	put_device(link->consumer);
 522	put_device(link->supplier);
 523	kfree(link);
 524}
 525
 526static void devlink_dev_release(struct device *dev)
 527{
 528	struct device_link *link = to_devlink(dev);
 529
 530	INIT_WORK(&link->rm_work, device_link_release_fn);
 531	/*
 532	 * It may take a while to complete this work because of the SRCU
 533	 * synchronization in device_link_release_fn() and if the consumer or
 534	 * supplier devices get deleted when it runs, so put it into the
 535	 * dedicated workqueue.
 536	 */
 537	queue_work(device_link_wq, &link->rm_work);
 538}
 539
 540/**
 541 * device_link_wait_removal - Wait for ongoing devlink removal jobs to terminate
 542 */
 543void device_link_wait_removal(void)
 544{
 545	/*
 546	 * devlink removal jobs are queued in the dedicated work queue.
 547	 * To be sure that all removal jobs are terminated, ensure that any
 548	 * scheduled work has run to completion.
 549	 */
 550	flush_workqueue(device_link_wq);
 551}
 552EXPORT_SYMBOL_GPL(device_link_wait_removal);
 553
 554static const struct class devlink_class = {
 555	.name = "devlink",
 556	.dev_groups = devlink_groups,
 557	.dev_release = devlink_dev_release,
 558};
 559
 560static int devlink_add_symlinks(struct device *dev)
 561{
 562	char *buf_con __free(kfree) = NULL, *buf_sup __free(kfree) = NULL;
 563	int ret;
 564	struct device_link *link = to_devlink(dev);
 565	struct device *sup = link->supplier;
 566	struct device *con = link->consumer;
 567
 568	ret = sysfs_create_link(&link->link_dev.kobj, &sup->kobj, "supplier");
 569	if (ret)
 570		goto out;
 571
 572	ret = sysfs_create_link(&link->link_dev.kobj, &con->kobj, "consumer");
 573	if (ret)
 574		goto err_con;
 575
 576	buf_con = kasprintf(GFP_KERNEL, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
 577	if (!buf_con) {
 578		ret = -ENOMEM;
 579		goto err_con_dev;
 580	}
 581
 582	ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf_con);
 583	if (ret)
 584		goto err_con_dev;
 585
 586	buf_sup = kasprintf(GFP_KERNEL, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
 587	if (!buf_sup) {
 588		ret = -ENOMEM;
 589		goto err_sup_dev;
 590	}
 591
 592	ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf_sup);
 593	if (ret)
 594		goto err_sup_dev;
 595
 596	goto out;
 597
 598err_sup_dev:
 599	sysfs_remove_link(&sup->kobj, buf_con);
 600err_con_dev:
 601	sysfs_remove_link(&link->link_dev.kobj, "consumer");
 602err_con:
 603	sysfs_remove_link(&link->link_dev.kobj, "supplier");
 604out:
 605	return ret;
 606}
 607
 608static void devlink_remove_symlinks(struct device *dev)
 609{
 610	char *buf_con __free(kfree) = NULL, *buf_sup __free(kfree) = NULL;
 611	struct device_link *link = to_devlink(dev);
 612	struct device *sup = link->supplier;
 613	struct device *con = link->consumer;
 614
 615	sysfs_remove_link(&link->link_dev.kobj, "consumer");
 616	sysfs_remove_link(&link->link_dev.kobj, "supplier");
 617
 618	if (device_is_registered(con)) {
 619		buf_sup = kasprintf(GFP_KERNEL, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
 620		if (!buf_sup)
 621			goto out;
 622		sysfs_remove_link(&con->kobj, buf_sup);
 623	}
 624
 625	buf_con = kasprintf(GFP_KERNEL, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
 626	if (!buf_con)
 627		goto out;
 628	sysfs_remove_link(&sup->kobj, buf_con);
 629
 630	return;
 631
 632out:
 633	WARN(1, "Unable to properly free device link symlinks!\n");
 634}
 635
 636static struct class_interface devlink_class_intf = {
 637	.class = &devlink_class,
 638	.add_dev = devlink_add_symlinks,
 639	.remove_dev = devlink_remove_symlinks,
 640};
 641
 642static int __init devlink_class_init(void)
 643{
 644	int ret;
 645
 646	ret = class_register(&devlink_class);
 647	if (ret)
 648		return ret;
 649
 650	ret = class_interface_register(&devlink_class_intf);
 651	if (ret)
 652		class_unregister(&devlink_class);
 653
 654	return ret;
 655}
 656postcore_initcall(devlink_class_init);
 657
 658#define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
 659			       DL_FLAG_AUTOREMOVE_SUPPLIER | \
 660			       DL_FLAG_AUTOPROBE_CONSUMER  | \
 661			       DL_FLAG_SYNC_STATE_ONLY | \
 662			       DL_FLAG_INFERRED | \
 663			       DL_FLAG_CYCLE)
 664
 665#define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
 666			    DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
 667
 668/**
 669 * device_link_add - Create a link between two devices.
 670 * @consumer: Consumer end of the link.
 671 * @supplier: Supplier end of the link.
 672 * @flags: Link flags.
 673 *
 674 * Return: On success, a device_link struct will be returned.
 675 *         On error or invalid flag settings, NULL will be returned.
 676 *
 677 * The caller is responsible for the proper synchronization of the link creation
 678 * with runtime PM.  First, setting the DL_FLAG_PM_RUNTIME flag will cause the
 679 * runtime PM framework to take the link into account.  Second, if the
 680 * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
 681 * be forced into the active meta state and reference-counted upon the creation
 682 * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
 683 * ignored.
 684 *
 685 * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
 686 * expected to release the link returned by it directly with the help of either
 687 * device_link_del() or device_link_remove().
 688 *
 689 * If that flag is not set, however, the caller of this function is handing the
 690 * management of the link over to the driver core entirely and its return value
 691 * can only be used to check whether or not the link is present.  In that case,
 692 * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
 693 * flags can be used to indicate to the driver core when the link can be safely
 694 * deleted.  Namely, setting one of them in @flags indicates to the driver core
 695 * that the link is not going to be used (by the given caller of this function)
 696 * after unbinding the consumer or supplier driver, respectively, from its
 697 * device, so the link can be deleted at that point.  If none of them is set,
 698 * the link will be maintained until one of the devices pointed to by it (either
 699 * the consumer or the supplier) is unregistered.
 700 *
 701 * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
 702 * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
 703 * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
 704 * be used to request the driver core to automatically probe for a consumer
 705 * driver after successfully binding a driver to the supplier device.
 706 *
 707 * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
 708 * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
 709 * the same time is invalid and will cause NULL to be returned upfront.
 710 * However, if a device link between the given @consumer and @supplier pair
 711 * exists already when this function is called for them, the existing link will
 712 * be returned regardless of its current type and status (the link's flags may
 713 * be modified then).  The caller of this function is then expected to treat
 714 * the link as though it has just been created, so (in particular) if
 715 * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
 716 * explicitly when not needed any more (as stated above).
 717 *
 718 * A side effect of the link creation is re-ordering of dpm_list and the
 719 * devices_kset list by moving the consumer device and all devices depending
 720 * on it to the ends of these lists (that does not happen to devices that have
 721 * not been registered when this function is called).
 722 *
 723 * The supplier device is required to be registered when this function is called
 724 * and NULL will be returned if that is not the case.  The consumer device need
 725 * not be registered, however.
 726 */
 727struct device_link *device_link_add(struct device *consumer,
 728				    struct device *supplier, u32 flags)
 729{
 730	struct device_link *link;
 731
 732	if (!consumer || !supplier || consumer == supplier ||
 733	    flags & ~DL_ADD_VALID_FLAGS ||
 734	    (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
 735	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
 736	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
 737		      DL_FLAG_AUTOREMOVE_SUPPLIER)))
 738		return NULL;
 739
 740	if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
 741		if (pm_runtime_get_sync(supplier) < 0) {
 742			pm_runtime_put_noidle(supplier);
 743			return NULL;
 744		}
 745	}
 746
 747	if (!(flags & DL_FLAG_STATELESS))
 748		flags |= DL_FLAG_MANAGED;
 749
 750	if (flags & DL_FLAG_SYNC_STATE_ONLY &&
 751	    !device_link_flag_is_sync_state_only(flags))
 752		return NULL;
 753
 754	device_links_write_lock();
 755	device_pm_lock();
 756
 757	/*
 758	 * If the supplier has not been fully registered yet or there is a
 759	 * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
 760	 * the supplier already in the graph, return NULL. If the link is a
 761	 * SYNC_STATE_ONLY link, we don't check for reverse dependencies
 762	 * because it only affects sync_state() callbacks.
 763	 */
 764	if (!device_pm_initialized(supplier)
 765	    || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
 766		  device_is_dependent(consumer, supplier))) {
 767		link = NULL;
 768		goto out;
 769	}
 770
 771	/*
 772	 * SYNC_STATE_ONLY links are useless once a consumer device has probed.
 773	 * So, only create it if the consumer hasn't probed yet.
 774	 */
 775	if (flags & DL_FLAG_SYNC_STATE_ONLY &&
 776	    consumer->links.status != DL_DEV_NO_DRIVER &&
 777	    consumer->links.status != DL_DEV_PROBING) {
 778		link = NULL;
 779		goto out;
 780	}
 781
 782	/*
 783	 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
 784	 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
 785	 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
 786	 */
 787	if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
 788		flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
 789
 790	list_for_each_entry(link, &supplier->links.consumers, s_node) {
 791		if (link->consumer != consumer)
 792			continue;
 793
 794		if (device_link_test(link, DL_FLAG_INFERRED) &&
 795		    !(flags & DL_FLAG_INFERRED))
 796			link->flags &= ~DL_FLAG_INFERRED;
 797
 798		if (flags & DL_FLAG_PM_RUNTIME) {
 799			if (!device_link_test(link, DL_FLAG_PM_RUNTIME)) {
 800				pm_runtime_new_link(consumer);
 801				link->flags |= DL_FLAG_PM_RUNTIME;
 802			}
 803			if (flags & DL_FLAG_RPM_ACTIVE)
 804				refcount_inc(&link->rpm_active);
 805		}
 806
 807		if (flags & DL_FLAG_STATELESS) {
 808			kref_get(&link->kref);
 809			if (device_link_test(link, DL_FLAG_SYNC_STATE_ONLY) &&
 810			    !device_link_test(link, DL_FLAG_STATELESS)) {
 811				link->flags |= DL_FLAG_STATELESS;
 812				goto reorder;
 813			} else {
 814				link->flags |= DL_FLAG_STATELESS;
 815				goto out;
 816			}
 817		}
 818
 819		/*
 820		 * If the life time of the link following from the new flags is
 821		 * longer than indicated by the flags of the existing link,
 822		 * update the existing link to stay around longer.
 823		 */
 824		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
 825			if (device_link_test(link, DL_FLAG_AUTOREMOVE_CONSUMER)) {
 826				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
 827				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
 828			}
 829		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
 830			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
 831					 DL_FLAG_AUTOREMOVE_SUPPLIER);
 832		}
 833		if (!device_link_test(link, DL_FLAG_MANAGED)) {
 834			kref_get(&link->kref);
 835			link->flags |= DL_FLAG_MANAGED;
 836			device_link_init_status(link, consumer, supplier);
 837		}
 838		if (device_link_test(link, DL_FLAG_SYNC_STATE_ONLY) &&
 839		    !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
 840			link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
 841			goto reorder;
 842		}
 843
 844		goto out;
 845	}
 846
 847	link = kzalloc(sizeof(*link), GFP_KERNEL);
 848	if (!link)
 849		goto out;
 850
 851	refcount_set(&link->rpm_active, 1);
 852
 853	get_device(supplier);
 854	link->supplier = supplier;
 855	INIT_LIST_HEAD(&link->s_node);
 856	get_device(consumer);
 857	link->consumer = consumer;
 858	INIT_LIST_HEAD(&link->c_node);
 859	link->flags = flags;
 860	kref_init(&link->kref);
 861
 862	link->link_dev.class = &devlink_class;
 863	device_set_pm_not_required(&link->link_dev);
 864	dev_set_name(&link->link_dev, "%s:%s--%s:%s",
 865		     dev_bus_name(supplier), dev_name(supplier),
 866		     dev_bus_name(consumer), dev_name(consumer));
 867	if (device_register(&link->link_dev)) {
 868		put_device(&link->link_dev);
 869		link = NULL;
 870		goto out;
 871	}
 872
 873	if (flags & DL_FLAG_PM_RUNTIME) {
 874		if (flags & DL_FLAG_RPM_ACTIVE)
 875			refcount_inc(&link->rpm_active);
 876
 877		pm_runtime_new_link(consumer);
 878	}
 879
 880	/* Determine the initial link state. */
 881	if (flags & DL_FLAG_STATELESS)
 882		link->status = DL_STATE_NONE;
 883	else
 884		device_link_init_status(link, consumer, supplier);
 885
 886	/*
 887	 * Some callers expect the link creation during consumer driver probe to
 888	 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
 889	 */
 890	if (link->status == DL_STATE_CONSUMER_PROBE &&
 891	    flags & DL_FLAG_PM_RUNTIME)
 892		pm_runtime_resume(supplier);
 893
 894	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
 895	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
 896
 897	if (flags & DL_FLAG_SYNC_STATE_ONLY) {
 898		dev_dbg(consumer,
 899			"Linked as a sync state only consumer to %s\n",
 900			dev_name(supplier));
 901		goto out;
 902	}
 903
 904reorder:
 905	/*
 906	 * Move the consumer and all of the devices depending on it to the end
 907	 * of dpm_list and the devices_kset list.
 908	 *
 909	 * It is necessary to hold dpm_list locked throughout all that or else
 910	 * we may end up suspending with a wrong ordering of it.
 911	 */
 912	device_reorder_to_tail(consumer, NULL);
 913
 914	dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
 915
 916out:
 917	device_pm_unlock();
 918	device_links_write_unlock();
 919
 920	if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
 921		pm_runtime_put(supplier);
 922
 923	return link;
 924}
 925EXPORT_SYMBOL_GPL(device_link_add);
 926
 927static void __device_link_del(struct kref *kref)
 928{
 929	struct device_link *link = container_of(kref, struct device_link, kref);
 930
 931	dev_dbg(link->consumer, "Dropping the link to %s\n",
 932		dev_name(link->supplier));
 933
 934	pm_runtime_drop_link(link);
 935
 936	device_link_remove_from_lists(link);
 937	device_unregister(&link->link_dev);
 938}
 939
 940static void device_link_put_kref(struct device_link *link)
 941{
 942	if (device_link_test(link, DL_FLAG_STATELESS))
 943		kref_put(&link->kref, __device_link_del);
 944	else if (!device_is_registered(link->consumer))
 945		__device_link_del(&link->kref);
 946	else
 947		WARN(1, "Unable to drop a managed device link reference\n");
 948}
 949
 950/**
 951 * device_link_del - Delete a stateless link between two devices.
 952 * @link: Device link to delete.
 953 *
 954 * The caller must ensure proper synchronization of this function with runtime
 955 * PM.  If the link was added multiple times, it needs to be deleted as often.
 956 * Care is required for hotplugged devices:  Their links are purged on removal
 957 * and calling device_link_del() is then no longer allowed.
 958 */
 959void device_link_del(struct device_link *link)
 960{
 961	device_links_write_lock();
 962	device_link_put_kref(link);
 963	device_links_write_unlock();
 964}
 965EXPORT_SYMBOL_GPL(device_link_del);
 966
 967/**
 968 * device_link_remove - Delete a stateless link between two devices.
 969 * @consumer: Consumer end of the link.
 970 * @supplier: Supplier end of the link.
 971 *
 972 * The caller must ensure proper synchronization of this function with runtime
 973 * PM.
 974 */
 975void device_link_remove(void *consumer, struct device *supplier)
 976{
 977	struct device_link *link;
 978
 979	if (WARN_ON(consumer == supplier))
 980		return;
 981
 982	device_links_write_lock();
 983
 984	list_for_each_entry(link, &supplier->links.consumers, s_node) {
 985		if (link->consumer == consumer) {
 986			device_link_put_kref(link);
 987			break;
 988		}
 989	}
 990
 991	device_links_write_unlock();
 992}
 993EXPORT_SYMBOL_GPL(device_link_remove);
 994
 995static void device_links_missing_supplier(struct device *dev)
 996{
 997	struct device_link *link;
 998
 999	list_for_each_entry(link, &dev->links.suppliers, c_node) {
1000		if (link->status != DL_STATE_CONSUMER_PROBE)
1001			continue;
1002
1003		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1004			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1005		} else {
1006			WARN_ON(!device_link_test(link, DL_FLAG_SYNC_STATE_ONLY));
1007			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1008		}
1009	}
1010}
1011
1012static bool dev_is_best_effort(struct device *dev)
1013{
1014	return (fw_devlink_best_effort && dev->can_match) ||
1015		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
1016}
1017
1018static struct fwnode_handle *fwnode_links_check_suppliers(
1019						struct fwnode_handle *fwnode)
1020{
1021	struct fwnode_link *link;
1022
1023	if (!fwnode || fw_devlink_is_permissive())
1024		return NULL;
1025
1026	list_for_each_entry(link, &fwnode->suppliers, c_hook)
1027		if (!(link->flags &
1028		      (FWLINK_FLAG_CYCLE | FWLINK_FLAG_IGNORE)))
1029			return link->supplier;
1030
1031	return NULL;
1032}
1033
1034/**
1035 * device_links_check_suppliers - Check presence of supplier drivers.
1036 * @dev: Consumer device.
1037 *
1038 * Check links from this device to any suppliers.  Walk the list of the device's
1039 * links to suppliers and see if all of them are available.  If not, simply
1040 * return -EPROBE_DEFER.
1041 *
1042 * We need to guarantee that the supplier will not go away after the check has
1043 * been positive here.  It only can go away in __device_release_driver() and
1044 * that function  checks the device's links to consumers.  This means we need to
1045 * mark the link as "consumer probe in progress" to make the supplier removal
1046 * wait for us to complete (or bad things may happen).
1047 *
1048 * Links without the DL_FLAG_MANAGED flag set are ignored.
1049 */
1050int device_links_check_suppliers(struct device *dev)
1051{
1052	struct device_link *link;
1053	int ret = 0, fwnode_ret = 0;
1054	struct fwnode_handle *sup_fw;
1055
1056	/*
1057	 * Device waiting for supplier to become available is not allowed to
1058	 * probe.
1059	 */
1060	scoped_guard(mutex, &fwnode_link_lock) {
1061		sup_fw = fwnode_links_check_suppliers(dev->fwnode);
1062		if (sup_fw) {
1063			if (dev_is_best_effort(dev))
1064				fwnode_ret = -EAGAIN;
1065			else
1066				return dev_err_probe(dev, -EPROBE_DEFER,
1067						     "wait for supplier %pfwf\n", sup_fw);
1068		}
1069	}
1070
1071	device_links_write_lock();
1072
1073	list_for_each_entry(link, &dev->links.suppliers, c_node) {
1074		if (!device_link_test(link, DL_FLAG_MANAGED))
1075			continue;
1076
1077		if (link->status != DL_STATE_AVAILABLE &&
1078		    !device_link_test(link, DL_FLAG_SYNC_STATE_ONLY)) {
1079
1080			if (dev_is_best_effort(dev) &&
1081			    device_link_test(link, DL_FLAG_INFERRED) &&
1082			    !link->supplier->can_match) {
1083				ret = -EAGAIN;
1084				continue;
1085			}
1086
1087			device_links_missing_supplier(dev);
1088			ret = dev_err_probe(dev, -EPROBE_DEFER,
1089					    "supplier %s not ready\n", dev_name(link->supplier));
1090			break;
1091		}
1092		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1093	}
1094	dev->links.status = DL_DEV_PROBING;
1095
1096	device_links_write_unlock();
1097
1098	return ret ? ret : fwnode_ret;
1099}
1100
1101/**
1102 * __device_links_queue_sync_state - Queue a device for sync_state() callback
1103 * @dev: Device to call sync_state() on
1104 * @list: List head to queue the @dev on
1105 *
1106 * Queues a device for a sync_state() callback when the device links write lock
1107 * isn't held. This allows the sync_state() execution flow to use device links
1108 * APIs.  The caller must ensure this function is called with
1109 * device_links_write_lock() held.
1110 *
1111 * This function does a get_device() to make sure the device is not freed while
1112 * on this list.
1113 *
1114 * So the caller must also ensure that device_links_flush_sync_list() is called
1115 * as soon as the caller releases device_links_write_lock().  This is necessary
1116 * to make sure the sync_state() is called in a timely fashion and the
1117 * put_device() is called on this device.
1118 */
1119static void __device_links_queue_sync_state(struct device *dev,
1120					    struct list_head *list)
1121{
1122	struct device_link *link;
1123
1124	if (!dev_has_sync_state(dev))
1125		return;
1126	if (dev->state_synced)
1127		return;
1128
1129	list_for_each_entry(link, &dev->links.consumers, s_node) {
1130		if (!device_link_test(link, DL_FLAG_MANAGED))
1131			continue;
1132		if (link->status != DL_STATE_ACTIVE)
1133			return;
1134	}
1135
1136	/*
1137	 * Set the flag here to avoid adding the same device to a list more
1138	 * than once. This can happen if new consumers get added to the device
1139	 * and probed before the list is flushed.
1140	 */
1141	dev->state_synced = true;
1142
1143	if (WARN_ON(!list_empty(&dev->links.defer_sync)))
1144		return;
1145
1146	get_device(dev);
1147	list_add_tail(&dev->links.defer_sync, list);
1148}
1149
1150/**
1151 * device_links_flush_sync_list - Call sync_state() on a list of devices
1152 * @list: List of devices to call sync_state() on
1153 * @dont_lock_dev: Device for which lock is already held by the caller
1154 *
1155 * Calls sync_state() on all the devices that have been queued for it. This
1156 * function is used in conjunction with __device_links_queue_sync_state(). The
1157 * @dont_lock_dev parameter is useful when this function is called from a
1158 * context where a device lock is already held.
1159 */
1160static void device_links_flush_sync_list(struct list_head *list,
1161					 struct device *dont_lock_dev)
1162{
1163	struct device *dev, *tmp;
1164
1165	list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
1166		list_del_init(&dev->links.defer_sync);
1167
1168		if (dev != dont_lock_dev)
1169			device_lock(dev);
1170
1171		dev_sync_state(dev);
1172
1173		if (dev != dont_lock_dev)
1174			device_unlock(dev);
1175
1176		put_device(dev);
1177	}
1178}
1179
1180void device_links_supplier_sync_state_pause(void)
1181{
1182	device_links_write_lock();
1183	defer_sync_state_count++;
1184	device_links_write_unlock();
1185}
1186
1187void device_links_supplier_sync_state_resume(void)
1188{
1189	struct device *dev, *tmp;
1190	LIST_HEAD(sync_list);
1191
1192	device_links_write_lock();
1193	if (!defer_sync_state_count) {
1194		WARN(true, "Unmatched sync_state pause/resume!");
1195		goto out;
1196	}
1197	defer_sync_state_count--;
1198	if (defer_sync_state_count)
1199		goto out;
1200
1201	list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
1202		/*
1203		 * Delete from deferred_sync list before queuing it to
1204		 * sync_list because defer_sync is used for both lists.
1205		 */
1206		list_del_init(&dev->links.defer_sync);
1207		__device_links_queue_sync_state(dev, &sync_list);
1208	}
1209out:
1210	device_links_write_unlock();
1211
1212	device_links_flush_sync_list(&sync_list, NULL);
1213}
1214
1215static int sync_state_resume_initcall(void)
1216{
1217	device_links_supplier_sync_state_resume();
1218	return 0;
1219}
1220late_initcall(sync_state_resume_initcall);
1221
1222static void __device_links_supplier_defer_sync(struct device *sup)
1223{
1224	if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup))
1225		list_add_tail(&sup->links.defer_sync, &deferred_sync);
1226}
1227
1228static void device_link_drop_managed(struct device_link *link)
1229{
1230	link->flags &= ~DL_FLAG_MANAGED;
1231	WRITE_ONCE(link->status, DL_STATE_NONE);
1232	kref_put(&link->kref, __device_link_del);
1233}
1234
1235static ssize_t waiting_for_supplier_show(struct device *dev,
1236					 struct device_attribute *attr,
1237					 char *buf)
1238{
1239	bool val;
1240
1241	device_lock(dev);
1242	scoped_guard(mutex, &fwnode_link_lock)
1243		val = !!fwnode_links_check_suppliers(dev->fwnode);
1244	device_unlock(dev);
1245	return sysfs_emit(buf, "%u\n", val);
1246}
1247static DEVICE_ATTR_RO(waiting_for_supplier);
1248
1249/**
1250 * device_links_force_bind - Prepares device to be force bound
1251 * @dev: Consumer device.
1252 *
1253 * device_bind_driver() force binds a device to a driver without calling any
1254 * driver probe functions. So the consumer really isn't going to wait for any
1255 * supplier before it's bound to the driver. We still want the device link
1256 * states to be sensible when this happens.
1257 *
1258 * In preparation for device_bind_driver(), this function goes through each
1259 * supplier device links and checks if the supplier is bound. If it is, then
1260 * the device link status is set to CONSUMER_PROBE. Otherwise, the device link
1261 * is dropped. Links without the DL_FLAG_MANAGED flag set are ignored.
1262 */
1263void device_links_force_bind(struct device *dev)
1264{
1265	struct device_link *link, *ln;
1266
1267	device_links_write_lock();
1268
1269	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1270		if (!device_link_test(link, DL_FLAG_MANAGED))
1271			continue;
1272
1273		if (link->status != DL_STATE_AVAILABLE) {
1274			device_link_drop_managed(link);
1275			continue;
1276		}
1277		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1278	}
1279	dev->links.status = DL_DEV_PROBING;
1280
1281	device_links_write_unlock();
1282}
1283
1284/**
1285 * device_links_driver_bound - Update device links after probing its driver.
1286 * @dev: Device to update the links for.
1287 *
1288 * The probe has been successful, so update links from this device to any
1289 * consumers by changing their status to "available".
1290 *
1291 * Also change the status of @dev's links to suppliers to "active".
1292 *
1293 * Links without the DL_FLAG_MANAGED flag set are ignored.
1294 */
1295void device_links_driver_bound(struct device *dev)
1296{
1297	struct device_link *link, *ln;
1298	LIST_HEAD(sync_list);
1299
1300	/*
1301	 * If a device binds successfully, it's expected to have created all
1302	 * the device links it needs to or make new device links as it needs
1303	 * them. So, fw_devlink no longer needs to create device links to any
1304	 * of the device's suppliers.
1305	 *
1306	 * Also, if a child firmware node of this bound device is not added as a
1307	 * device by now, assume it is never going to be added. Make this bound
1308	 * device the fallback supplier to the dangling consumers of the child
1309	 * firmware node because this bound device is probably implementing the
1310	 * child firmware node functionality and we don't want the dangling
1311	 * consumers to defer probe indefinitely waiting for a device for the
1312	 * child firmware node.
1313	 */
1314	if (dev->fwnode && dev->fwnode->dev == dev) {
1315		struct fwnode_handle *child;
1316
1317		fwnode_links_purge_suppliers(dev->fwnode);
1318
1319		guard(mutex)(&fwnode_link_lock);
1320
1321		fwnode_for_each_available_child_node(dev->fwnode, child)
1322			__fw_devlink_pickup_dangling_consumers(child,
1323							       dev->fwnode);
1324		__fw_devlink_link_to_consumers(dev);
1325	}
1326	device_remove_file(dev, &dev_attr_waiting_for_supplier);
1327
1328	device_links_write_lock();
1329
1330	list_for_each_entry(link, &dev->links.consumers, s_node) {
1331		if (!device_link_test(link, DL_FLAG_MANAGED))
1332			continue;
1333
1334		/*
1335		 * Links created during consumer probe may be in the "consumer
1336		 * probe" state to start with if the supplier is still probing
1337		 * when they are created and they may become "active" if the
1338		 * consumer probe returns first.  Skip them here.
1339		 */
1340		if (link->status == DL_STATE_CONSUMER_PROBE ||
1341		    link->status == DL_STATE_ACTIVE)
1342			continue;
1343
1344		WARN_ON(link->status != DL_STATE_DORMANT);
1345		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1346
1347		if (device_link_test(link, DL_FLAG_AUTOPROBE_CONSUMER))
1348			driver_deferred_probe_add(link->consumer);
1349	}
1350
1351	if (defer_sync_state_count)
1352		__device_links_supplier_defer_sync(dev);
1353	else
1354		__device_links_queue_sync_state(dev, &sync_list);
1355
1356	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1357		struct device *supplier;
1358
1359		if (!device_link_test(link, DL_FLAG_MANAGED))
1360			continue;
1361
1362		supplier = link->supplier;
1363		if (device_link_test(link, DL_FLAG_SYNC_STATE_ONLY)) {
1364			/*
1365			 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
1366			 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
1367			 * save to drop the managed link completely.
1368			 */
1369			device_link_drop_managed(link);
1370		} else if (dev_is_best_effort(dev) &&
1371			   device_link_test(link, DL_FLAG_INFERRED) &&
1372			   link->status != DL_STATE_CONSUMER_PROBE &&
1373			   !link->supplier->can_match) {
1374			/*
1375			 * When dev_is_best_effort() is true, we ignore device
1376			 * links to suppliers that don't have a driver.  If the
1377			 * consumer device still managed to probe, there's no
1378			 * point in maintaining a device link in a weird state
1379			 * (consumer probed before supplier). So delete it.
1380			 */
1381			device_link_drop_managed(link);
1382		} else {
1383			WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
1384			WRITE_ONCE(link->status, DL_STATE_ACTIVE);
1385		}
1386
1387		/*
1388		 * This needs to be done even for the deleted
1389		 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
1390		 * device link that was preventing the supplier from getting a
1391		 * sync_state() call.
1392		 */
1393		if (defer_sync_state_count)
1394			__device_links_supplier_defer_sync(supplier);
1395		else
1396			__device_links_queue_sync_state(supplier, &sync_list);
1397	}
1398
1399	dev->links.status = DL_DEV_DRIVER_BOUND;
1400
1401	device_links_write_unlock();
1402
1403	device_links_flush_sync_list(&sync_list, dev);
1404}
1405
1406/**
1407 * __device_links_no_driver - Update links of a device without a driver.
1408 * @dev: Device without a drvier.
1409 *
1410 * Delete all non-persistent links from this device to any suppliers.
1411 *
1412 * Persistent links stay around, but their status is changed to "available",
1413 * unless they already are in the "supplier unbind in progress" state in which
1414 * case they need not be updated.
1415 *
1416 * Links without the DL_FLAG_MANAGED flag set are ignored.
1417 */
1418static void __device_links_no_driver(struct device *dev)
1419{
1420	struct device_link *link, *ln;
1421
1422	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1423		if (!device_link_test(link, DL_FLAG_MANAGED))
1424			continue;
1425
1426		if (device_link_test(link, DL_FLAG_AUTOREMOVE_CONSUMER)) {
1427			device_link_drop_managed(link);
1428			continue;
1429		}
1430
1431		if (link->status != DL_STATE_CONSUMER_PROBE &&
1432		    link->status != DL_STATE_ACTIVE)
1433			continue;
1434
1435		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1436			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1437		} else {
1438			WARN_ON(!device_link_test(link, DL_FLAG_SYNC_STATE_ONLY));
1439			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1440		}
1441	}
1442
1443	dev->links.status = DL_DEV_NO_DRIVER;
1444}
1445
1446/**
1447 * device_links_no_driver - Update links after failing driver probe.
1448 * @dev: Device whose driver has just failed to probe.
1449 *
1450 * Clean up leftover links to consumers for @dev and invoke
1451 * %__device_links_no_driver() to update links to suppliers for it as
1452 * appropriate.
1453 *
1454 * Links without the DL_FLAG_MANAGED flag set are ignored.
1455 */
1456void device_links_no_driver(struct device *dev)
1457{
1458	struct device_link *link;
1459
1460	device_links_write_lock();
1461
1462	list_for_each_entry(link, &dev->links.consumers, s_node) {
1463		if (!device_link_test(link, DL_FLAG_MANAGED))
1464			continue;
1465
1466		/*
1467		 * The probe has failed, so if the status of the link is
1468		 * "consumer probe" or "active", it must have been added by
1469		 * a probing consumer while this device was still probing.
1470		 * Change its state to "dormant", as it represents a valid
1471		 * relationship, but it is not functionally meaningful.
1472		 */
1473		if (link->status == DL_STATE_CONSUMER_PROBE ||
1474		    link->status == DL_STATE_ACTIVE)
1475			WRITE_ONCE(link->status, DL_STATE_DORMANT);
1476	}
1477
1478	__device_links_no_driver(dev);
1479
1480	device_links_write_unlock();
1481}
1482
1483/**
1484 * device_links_driver_cleanup - Update links after driver removal.
1485 * @dev: Device whose driver has just gone away.
1486 *
1487 * Update links to consumers for @dev by changing their status to "dormant" and
1488 * invoke %__device_links_no_driver() to update links to suppliers for it as
1489 * appropriate.
1490 *
1491 * Links without the DL_FLAG_MANAGED flag set are ignored.
1492 */
1493void device_links_driver_cleanup(struct device *dev)
1494{
1495	struct device_link *link, *ln;
1496
1497	device_links_write_lock();
1498
1499	list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
1500		if (!device_link_test(link, DL_FLAG_MANAGED))
1501			continue;
1502
1503		WARN_ON(device_link_test(link, DL_FLAG_AUTOREMOVE_CONSUMER));
1504		WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
1505
1506		/*
1507		 * autoremove the links between this @dev and its consumer
1508		 * devices that are not active, i.e. where the link state
1509		 * has moved to DL_STATE_SUPPLIER_UNBIND.
1510		 */
1511		if (link->status == DL_STATE_SUPPLIER_UNBIND &&
1512		    device_link_test(link, DL_FLAG_AUTOREMOVE_SUPPLIER))
1513			device_link_drop_managed(link);
1514
1515		WRITE_ONCE(link->status, DL_STATE_DORMANT);
1516	}
1517
1518	list_del_init(&dev->links.defer_sync);
1519	__device_links_no_driver(dev);
1520
1521	device_links_write_unlock();
1522}
1523
1524/**
1525 * device_links_busy - Check if there are any busy links to consumers.
1526 * @dev: Device to check.
1527 *
1528 * Check each consumer of the device and return 'true' if its link's status
1529 * is one of "consumer probe" or "active" (meaning that the given consumer is
1530 * probing right now or its driver is present).  Otherwise, change the link
1531 * state to "supplier unbind" to prevent the consumer from being probed
1532 * successfully going forward.
1533 *
1534 * Return 'false' if there are no probing or active consumers.
1535 *
1536 * Links without the DL_FLAG_MANAGED flag set are ignored.
1537 */
1538bool device_links_busy(struct device *dev)
1539{
1540	struct device_link *link;
1541	bool ret = false;
1542
1543	device_links_write_lock();
1544
1545	list_for_each_entry(link, &dev->links.consumers, s_node) {
1546		if (!device_link_test(link, DL_FLAG_MANAGED))
1547			continue;
1548
1549		if (link->status == DL_STATE_CONSUMER_PROBE
1550		    || link->status == DL_STATE_ACTIVE) {
1551			ret = true;
1552			break;
1553		}
1554		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1555	}
1556
1557	dev->links.status = DL_DEV_UNBINDING;
1558
1559	device_links_write_unlock();
1560	return ret;
1561}
1562
1563/**
1564 * device_links_unbind_consumers - Force unbind consumers of the given device.
1565 * @dev: Device to unbind the consumers of.
1566 *
1567 * Walk the list of links to consumers for @dev and if any of them is in the
1568 * "consumer probe" state, wait for all device probes in progress to complete
1569 * and start over.
1570 *
1571 * If that's not the case, change the status of the link to "supplier unbind"
1572 * and check if the link was in the "active" state.  If so, force the consumer
1573 * driver to unbind and start over (the consumer will not re-probe as we have
1574 * changed the state of the link already).
1575 *
1576 * Links without the DL_FLAG_MANAGED flag set are ignored.
1577 */
1578void device_links_unbind_consumers(struct device *dev)
1579{
1580	struct device_link *link;
1581
1582 start:
1583	device_links_write_lock();
1584
1585	list_for_each_entry(link, &dev->links.consumers, s_node) {
1586		enum device_link_state status;
1587
1588		if (!device_link_test(link, DL_FLAG_MANAGED) ||
1589		    device_link_test(link, DL_FLAG_SYNC_STATE_ONLY))
1590			continue;
1591
1592		status = link->status;
1593		if (status == DL_STATE_CONSUMER_PROBE) {
1594			device_links_write_unlock();
1595
1596			wait_for_device_probe();
1597			goto start;
1598		}
1599		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1600		if (status == DL_STATE_ACTIVE) {
1601			struct device *consumer = link->consumer;
1602
1603			get_device(consumer);
1604
1605			device_links_write_unlock();
1606
1607			device_release_driver_internal(consumer, NULL,
1608						       consumer->parent);
1609			put_device(consumer);
1610			goto start;
1611		}
1612	}
1613
1614	device_links_write_unlock();
1615}
1616
1617/**
1618 * device_links_purge - Delete existing links to other devices.
1619 * @dev: Target device.
1620 */
1621static void device_links_purge(struct device *dev)
1622{
1623	struct device_link *link, *ln;
1624
1625	if (dev->class == &devlink_class)
1626		return;
1627
1628	/*
1629	 * Delete all of the remaining links from this device to any other
1630	 * devices (either consumers or suppliers).
1631	 */
1632	device_links_write_lock();
1633
1634	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1635		WARN_ON(link->status == DL_STATE_ACTIVE);
1636		__device_link_del(&link->kref);
1637	}
1638
1639	list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
1640		WARN_ON(link->status != DL_STATE_DORMANT &&
1641			link->status != DL_STATE_NONE);
1642		__device_link_del(&link->kref);
1643	}
1644
1645	device_links_write_unlock();
1646}
1647
1648#define FW_DEVLINK_FLAGS_PERMISSIVE	(DL_FLAG_INFERRED | \
1649					 DL_FLAG_SYNC_STATE_ONLY)
1650#define FW_DEVLINK_FLAGS_ON		(DL_FLAG_INFERRED | \
1651					 DL_FLAG_AUTOPROBE_CONSUMER)
1652#define FW_DEVLINK_FLAGS_RPM		(FW_DEVLINK_FLAGS_ON | \
1653					 DL_FLAG_PM_RUNTIME)
1654
1655static u32 fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1656static int __init fw_devlink_setup(char *arg)
1657{
1658	if (!arg)
1659		return -EINVAL;
1660
1661	if (strcmp(arg, "off") == 0) {
1662		fw_devlink_flags = 0;
1663	} else if (strcmp(arg, "permissive") == 0) {
1664		fw_devlink_flags = FW_DEVLINK_FLAGS_PERMISSIVE;
1665	} else if (strcmp(arg, "on") == 0) {
1666		fw_devlink_flags = FW_DEVLINK_FLAGS_ON;
1667	} else if (strcmp(arg, "rpm") == 0) {
1668		fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1669	}
1670	return 0;
1671}
1672early_param("fw_devlink", fw_devlink_setup);
1673
1674static bool fw_devlink_strict;
1675static int __init fw_devlink_strict_setup(char *arg)
1676{
1677	return kstrtobool(arg, &fw_devlink_strict);
1678}
1679early_param("fw_devlink.strict", fw_devlink_strict_setup);
1680
1681#define FW_DEVLINK_SYNC_STATE_STRICT	0
1682#define FW_DEVLINK_SYNC_STATE_TIMEOUT	1
1683
1684#ifndef CONFIG_FW_DEVLINK_SYNC_STATE_TIMEOUT
1685static int fw_devlink_sync_state;
1686#else
1687static int fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1688#endif
1689
1690static int __init fw_devlink_sync_state_setup(char *arg)
1691{
1692	if (!arg)
1693		return -EINVAL;
1694
1695	if (strcmp(arg, "strict") == 0) {
1696		fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_STRICT;
1697		return 0;
1698	} else if (strcmp(arg, "timeout") == 0) {
1699		fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1700		return 0;
1701	}
1702	return -EINVAL;
1703}
1704early_param("fw_devlink.sync_state", fw_devlink_sync_state_setup);
1705
1706static inline u32 fw_devlink_get_flags(u8 fwlink_flags)
1707{
1708	if (fwlink_flags & FWLINK_FLAG_CYCLE)
1709		return FW_DEVLINK_FLAGS_PERMISSIVE | DL_FLAG_CYCLE;
1710
1711	return fw_devlink_flags;
1712}
1713
1714static bool fw_devlink_is_permissive(void)
1715{
1716	return fw_devlink_flags == FW_DEVLINK_FLAGS_PERMISSIVE;
1717}
1718
1719bool fw_devlink_is_strict(void)
1720{
1721	return fw_devlink_strict && !fw_devlink_is_permissive();
1722}
1723
1724static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
1725{
1726	if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
1727		return;
1728
1729	fwnode_call_int_op(fwnode, add_links);
1730	fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
1731}
1732
1733static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
1734{
1735	struct fwnode_handle *child = NULL;
1736
1737	fw_devlink_parse_fwnode(fwnode);
1738
1739	while ((child = fwnode_get_next_available_child_node(fwnode, child)))
1740		fw_devlink_parse_fwtree(child);
1741}
1742
1743static void fw_devlink_relax_link(struct device_link *link)
1744{
1745	if (!device_link_test(link, DL_FLAG_INFERRED))
1746		return;
1747
1748	if (device_link_flag_is_sync_state_only(link->flags))
1749		return;
1750
1751	pm_runtime_drop_link(link);
1752	link->flags = DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE;
1753	dev_dbg(link->consumer, "Relaxing link with %s\n",
1754		dev_name(link->supplier));
1755}
1756
1757static int fw_devlink_no_driver(struct device *dev, void *data)
1758{
1759	struct device_link *link = to_devlink(dev);
1760
1761	if (!link->supplier->can_match)
1762		fw_devlink_relax_link(link);
1763
1764	return 0;
1765}
1766
1767void fw_devlink_drivers_done(void)
1768{
1769	fw_devlink_drv_reg_done = true;
1770	device_links_write_lock();
1771	class_for_each_device(&devlink_class, NULL, NULL,
1772			      fw_devlink_no_driver);
1773	device_links_write_unlock();
1774}
1775
1776static int fw_devlink_dev_sync_state(struct device *dev, void *data)
1777{
1778	struct device_link *link = to_devlink(dev);
1779	struct device *sup = link->supplier;
1780
1781	if (!device_link_test(link, DL_FLAG_MANAGED) ||
1782	    link->status == DL_STATE_ACTIVE || sup->state_synced ||
1783	    !dev_has_sync_state(sup))
1784		return 0;
1785
1786	if (fw_devlink_sync_state == FW_DEVLINK_SYNC_STATE_STRICT) {
1787		dev_info(sup, "sync_state() pending due to %s\n",
1788			 dev_name(link->consumer));
1789		return 0;
1790	}
1791
1792	if (!list_empty(&sup->links.defer_sync))
1793		return 0;
1794
1795	dev_warn(sup, "Timed out. Forcing sync_state()\n");
1796	sup->state_synced = true;
1797	get_device(sup);
1798	list_add_tail(&sup->links.defer_sync, data);
1799
1800	return 0;
1801}
1802
1803void fw_devlink_probing_done(void)
1804{
1805	LIST_HEAD(sync_list);
1806
1807	device_links_write_lock();
1808	class_for_each_device(&devlink_class, NULL, &sync_list,
1809			      fw_devlink_dev_sync_state);
1810	device_links_write_unlock();
1811	device_links_flush_sync_list(&sync_list, NULL);
1812}
1813
1814/**
1815 * wait_for_init_devices_probe - Try to probe any device needed for init
1816 *
1817 * Some devices might need to be probed and bound successfully before the kernel
1818 * boot sequence can finish and move on to init/userspace. For example, a
1819 * network interface might need to be bound to be able to mount a NFS rootfs.
1820 *
1821 * With fw_devlink=on by default, some of these devices might be blocked from
1822 * probing because they are waiting on a optional supplier that doesn't have a
1823 * driver. While fw_devlink will eventually identify such devices and unblock
1824 * the probing automatically, it might be too late by the time it unblocks the
1825 * probing of devices. For example, the IP4 autoconfig might timeout before
1826 * fw_devlink unblocks probing of the network interface.
1827 *
1828 * This function is available to temporarily try and probe all devices that have
1829 * a driver even if some of their suppliers haven't been added or don't have
1830 * drivers.
1831 *
1832 * The drivers can then decide which of the suppliers are optional vs mandatory
1833 * and probe the device if possible. By the time this function returns, all such
1834 * "best effort" probes are guaranteed to be completed. If a device successfully
1835 * probes in this mode, we delete all fw_devlink discovered dependencies of that
1836 * device where the supplier hasn't yet probed successfully because they have to
1837 * be optional dependencies.
1838 *
1839 * Any devices that didn't successfully probe go back to being treated as if
1840 * this function was never called.
1841 *
1842 * This also means that some devices that aren't needed for init and could have
1843 * waited for their optional supplier to probe (when the supplier's module is
1844 * loaded later on) would end up probing prematurely with limited functionality.
1845 * So call this function only when boot would fail without it.
1846 */
1847void __init wait_for_init_devices_probe(void)
1848{
1849	if (!fw_devlink_flags || fw_devlink_is_permissive())
1850		return;
1851
1852	/*
1853	 * Wait for all ongoing probes to finish so that the "best effort" is
1854	 * only applied to devices that can't probe otherwise.
1855	 */
1856	wait_for_device_probe();
1857
1858	pr_info("Trying to probe devices needed for running init ...\n");
1859	fw_devlink_best_effort = true;
1860	driver_deferred_probe_trigger();
1861
1862	/*
1863	 * Wait for all "best effort" probes to finish before going back to
1864	 * normal enforcement.
1865	 */
1866	wait_for_device_probe();
1867	fw_devlink_best_effort = false;
1868}
1869
1870static void fw_devlink_unblock_consumers(struct device *dev)
1871{
1872	struct device_link *link;
1873
1874	if (!fw_devlink_flags || fw_devlink_is_permissive())
1875		return;
1876
1877	device_links_write_lock();
1878	list_for_each_entry(link, &dev->links.consumers, s_node)
1879		fw_devlink_relax_link(link);
1880	device_links_write_unlock();
1881}
1882
1883static bool fwnode_init_without_drv(struct fwnode_handle *fwnode)
1884{
1885	struct device *dev;
1886	bool ret;
1887
1888	if (!(fwnode->flags & FWNODE_FLAG_INITIALIZED))
1889		return false;
1890
1891	dev = get_dev_from_fwnode(fwnode);
1892	ret = !dev || dev->links.status == DL_DEV_NO_DRIVER;
1893	put_device(dev);
1894
1895	return ret;
1896}
1897
1898static bool fwnode_ancestor_init_without_drv(struct fwnode_handle *fwnode)
1899{
1900	struct fwnode_handle *parent;
1901
1902	fwnode_for_each_parent_node(fwnode, parent) {
1903		if (fwnode_init_without_drv(parent)) {
1904			fwnode_handle_put(parent);
1905			return true;
1906		}
1907	}
1908
1909	return false;
1910}
1911
1912/**
1913 * fwnode_is_ancestor_of - Test if @ancestor is ancestor of @child
1914 * @ancestor: Firmware which is tested for being an ancestor
1915 * @child: Firmware which is tested for being the child
1916 *
1917 * A node is considered an ancestor of itself too.
1918 *
1919 * Return: true if @ancestor is an ancestor of @child. Otherwise, returns false.
1920 */
1921static bool fwnode_is_ancestor_of(const struct fwnode_handle *ancestor,
1922				  const struct fwnode_handle *child)
1923{
1924	struct fwnode_handle *parent;
1925
1926	if (IS_ERR_OR_NULL(ancestor))
1927		return false;
1928
1929	if (child == ancestor)
1930		return true;
1931
1932	fwnode_for_each_parent_node(child, parent) {
1933		if (parent == ancestor) {
1934			fwnode_handle_put(parent);
1935			return true;
1936		}
1937	}
1938	return false;
1939}
1940
1941/**
1942 * fwnode_get_next_parent_dev - Find device of closest ancestor fwnode
1943 * @fwnode: firmware node
1944 *
1945 * Given a firmware node (@fwnode), this function finds its closest ancestor
1946 * firmware node that has a corresponding struct device and returns that struct
1947 * device.
1948 *
1949 * The caller is responsible for calling put_device() on the returned device
1950 * pointer.
1951 *
1952 * Return: a pointer to the device of the @fwnode's closest ancestor.
1953 */
1954static struct device *fwnode_get_next_parent_dev(const struct fwnode_handle *fwnode)
1955{
1956	struct fwnode_handle *parent;
1957	struct device *dev;
1958
1959	fwnode_for_each_parent_node(fwnode, parent) {
1960		dev = get_dev_from_fwnode(parent);
1961		if (dev) {
1962			fwnode_handle_put(parent);
1963			return dev;
1964		}
1965	}
1966	return NULL;
1967}
1968
1969/**
1970 * __fw_devlink_relax_cycles - Relax and mark dependency cycles.
1971 * @con_handle: Potential consumer device fwnode.
1972 * @sup_handle: Potential supplier's fwnode.
1973 *
1974 * Needs to be called with fwnode_lock and device link lock held.
1975 *
1976 * Check if @sup_handle or any of its ancestors or suppliers direct/indirectly
1977 * depend on @con. This function can detect multiple cyles between @sup_handle
1978 * and @con. When such dependency cycles are found, convert all device links
1979 * created solely by fw_devlink into SYNC_STATE_ONLY device links. Also, mark
1980 * all fwnode links in the cycle with FWLINK_FLAG_CYCLE so that when they are
1981 * converted into a device link in the future, they are created as
1982 * SYNC_STATE_ONLY device links. This is the equivalent of doing
1983 * fw_devlink=permissive just between the devices in the cycle. We need to do
1984 * this because, at this point, fw_devlink can't tell which of these
1985 * dependencies is not a real dependency.
1986 *
1987 * Return true if one or more cycles were found. Otherwise, return false.
1988 */
1989static bool __fw_devlink_relax_cycles(struct fwnode_handle *con_handle,
1990				 struct fwnode_handle *sup_handle)
1991{
1992	struct device *sup_dev = NULL, *par_dev = NULL, *con_dev = NULL;
1993	struct fwnode_link *link;
1994	struct device_link *dev_link;
1995	bool ret = false;
1996
1997	if (!sup_handle)
1998		return false;
1999
2000	/*
2001	 * We aren't trying to find all cycles. Just a cycle between con and
2002	 * sup_handle.
2003	 */
2004	if (sup_handle->flags & FWNODE_FLAG_VISITED)
2005		return false;
2006
2007	sup_handle->flags |= FWNODE_FLAG_VISITED;
2008
2009	/* Termination condition. */
2010	if (sup_handle == con_handle) {
2011		pr_debug("----- cycle: start -----\n");
2012		ret = true;
2013		goto out;
2014	}
2015
2016	sup_dev = get_dev_from_fwnode(sup_handle);
2017	con_dev = get_dev_from_fwnode(con_handle);
2018	/*
2019	 * If sup_dev is bound to a driver and @con hasn't started binding to a
2020	 * driver, sup_dev can't be a consumer of @con. So, no need to check
2021	 * further.
2022	 */
2023	if (sup_dev && sup_dev->links.status ==  DL_DEV_DRIVER_BOUND &&
2024	    con_dev && con_dev->links.status == DL_DEV_NO_DRIVER) {
2025		ret = false;
2026		goto out;
2027	}
2028
2029	list_for_each_entry(link, &sup_handle->suppliers, c_hook) {
2030		if (link->flags & FWLINK_FLAG_IGNORE)
2031			continue;
2032
2033		if (__fw_devlink_relax_cycles(con_handle, link->supplier)) {
2034			__fwnode_link_cycle(link);
2035			ret = true;
2036		}
2037	}
2038
2039	/*
2040	 * Give priority to device parent over fwnode parent to account for any
2041	 * quirks in how fwnodes are converted to devices.
2042	 */
2043	if (sup_dev)
2044		par_dev = get_device(sup_dev->parent);
2045	else
2046		par_dev = fwnode_get_next_parent_dev(sup_handle);
2047
2048	if (par_dev && __fw_devlink_relax_cycles(con_handle, par_dev->fwnode)) {
2049		pr_debug("%pfwf: cycle: child of %pfwf\n", sup_handle,
2050			 par_dev->fwnode);
2051		ret = true;
2052	}
2053
2054	if (!sup_dev)
2055		goto out;
2056
2057	list_for_each_entry(dev_link, &sup_dev->links.suppliers, c_node) {
2058		/*
2059		 * Ignore a SYNC_STATE_ONLY flag only if it wasn't marked as
2060		 * such due to a cycle.
2061		 */
2062		if (device_link_flag_is_sync_state_only(dev_link->flags) &&
2063		    !device_link_test(dev_link, DL_FLAG_CYCLE))
2064			continue;
2065
2066		if (__fw_devlink_relax_cycles(con_handle,
2067					      dev_link->supplier->fwnode)) {
2068			pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
2069				 dev_link->supplier->fwnode);
2070			fw_devlink_relax_link(dev_link);
2071			dev_link->flags |= DL_FLAG_CYCLE;
2072			ret = true;
2073		}
2074	}
2075
2076out:
2077	sup_handle->flags &= ~FWNODE_FLAG_VISITED;
2078	put_device(sup_dev);
2079	put_device(con_dev);
2080	put_device(par_dev);
2081	return ret;
2082}
2083
2084/**
2085 * fw_devlink_create_devlink - Create a device link from a consumer to fwnode
2086 * @con: consumer device for the device link
2087 * @sup_handle: fwnode handle of supplier
2088 * @link: fwnode link that's being converted to a device link
2089 *
2090 * This function will try to create a device link between the consumer device
2091 * @con and the supplier device represented by @sup_handle.
2092 *
2093 * The supplier has to be provided as a fwnode because incorrect cycles in
2094 * fwnode links can sometimes cause the supplier device to never be created.
2095 * This function detects such cases and returns an error if it cannot create a
2096 * device link from the consumer to a missing supplier.
2097 *
2098 * Returns,
2099 * 0 on successfully creating a device link
2100 * -EINVAL if the device link cannot be created as expected
2101 * -EAGAIN if the device link cannot be created right now, but it may be
2102 *  possible to do that in the future
2103 */
2104static int fw_devlink_create_devlink(struct device *con,
2105				     struct fwnode_handle *sup_handle,
2106				     struct fwnode_link *link)
2107{
2108	struct device *sup_dev;
2109	int ret = 0;
2110	u32 flags;
2111
2112	if (link->flags & FWLINK_FLAG_IGNORE)
2113		return 0;
2114
2115	/*
2116	 * In some cases, a device P might also be a supplier to its child node
2117	 * C. However, this would defer the probe of C until the probe of P
2118	 * completes successfully. This is perfectly fine in the device driver
2119	 * model. device_add() doesn't guarantee probe completion of the device
2120	 * by the time it returns.
2121	 *
2122	 * However, there are a few drivers that assume C will finish probing
2123	 * as soon as it's added and before P finishes probing. So, we provide
2124	 * a flag to let fw_devlink know not to delay the probe of C until the
2125	 * probe of P completes successfully.
2126	 *
2127	 * When such a flag is set, we can't create device links where P is the
2128	 * supplier of C as that would delay the probe of C.
2129	 */
2130	if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
2131	    fwnode_is_ancestor_of(sup_handle, con->fwnode))
2132		return -EINVAL;
2133
2134	/*
2135	 * Don't try to optimize by not calling the cycle detection logic under
2136	 * certain conditions. There's always some corner case that won't get
2137	 * detected.
2138	 */
2139	device_links_write_lock();
2140	if (__fw_devlink_relax_cycles(link->consumer, sup_handle)) {
2141		__fwnode_link_cycle(link);
2142		pr_debug("----- cycle: end -----\n");
2143		pr_info("%pfwf: Fixed dependency cycle(s) with %pfwf\n",
2144			link->consumer, sup_handle);
2145	}
2146	device_links_write_unlock();
2147
2148	if (con->fwnode == link->consumer)
2149		flags = fw_devlink_get_flags(link->flags);
2150	else
2151		flags = FW_DEVLINK_FLAGS_PERMISSIVE;
2152
2153	if (sup_handle->flags & FWNODE_FLAG_NOT_DEVICE)
2154		sup_dev = fwnode_get_next_parent_dev(sup_handle);
2155	else
2156		sup_dev = get_dev_from_fwnode(sup_handle);
2157
2158	if (sup_dev) {
2159		/*
2160		 * If it's one of those drivers that don't actually bind to
2161		 * their device using driver core, then don't wait on this
2162		 * supplier device indefinitely.
2163		 */
2164		if (sup_dev->links.status == DL_DEV_NO_DRIVER &&
2165		    sup_handle->flags & FWNODE_FLAG_INITIALIZED) {
2166			dev_dbg(con,
2167				"Not linking %pfwf - dev might never probe\n",
2168				sup_handle);
2169			ret = -EINVAL;
2170			goto out;
2171		}
2172
2173		if (con != sup_dev && !device_link_add(con, sup_dev, flags)) {
2174			dev_err(con, "Failed to create device link (0x%x) with supplier %s for %pfwf\n",
2175				flags, dev_name(sup_dev), link->consumer);
2176			ret = -EINVAL;
2177		}
2178
2179		goto out;
2180	}
2181
2182	/*
2183	 * Supplier or supplier's ancestor already initialized without a struct
2184	 * device or being probed by a driver.
2185	 */
2186	if (fwnode_init_without_drv(sup_handle) ||
2187	    fwnode_ancestor_init_without_drv(sup_handle)) {
2188		dev_dbg(con, "Not linking %pfwf - might never become dev\n",
2189			sup_handle);
2190		return -EINVAL;
2191	}
2192
2193	ret = -EAGAIN;
2194out:
2195	put_device(sup_dev);
2196	return ret;
2197}
2198
2199/**
2200 * __fw_devlink_link_to_consumers - Create device links to consumers of a device
2201 * @dev: Device that needs to be linked to its consumers
2202 *
2203 * This function looks at all the consumer fwnodes of @dev and creates device
2204 * links between the consumer device and @dev (supplier).
2205 *
2206 * If the consumer device has not been added yet, then this function creates a
2207 * SYNC_STATE_ONLY link between @dev (supplier) and the closest ancestor device
2208 * of the consumer fwnode. This is necessary to make sure @dev doesn't get a
2209 * sync_state() callback before the real consumer device gets to be added and
2210 * then probed.
2211 *
2212 * Once device links are created from the real consumer to @dev (supplier), the
2213 * fwnode links are deleted.
2214 */
2215static void __fw_devlink_link_to_consumers(struct device *dev)
2216{
2217	struct fwnode_handle *fwnode = dev->fwnode;
2218	struct fwnode_link *link, *tmp;
2219
2220	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) {
2221		struct device *con_dev;
2222		bool own_link = true;
2223		int ret;
2224
2225		con_dev = get_dev_from_fwnode(link->consumer);
2226		/*
2227		 * If consumer device is not available yet, make a "proxy"
2228		 * SYNC_STATE_ONLY link from the consumer's parent device to
2229		 * the supplier device. This is necessary to make sure the
2230		 * supplier doesn't get a sync_state() callback before the real
2231		 * consumer can create a device link to the supplier.
2232		 *
2233		 * This proxy link step is needed to handle the case where the
2234		 * consumer's parent device is added before the supplier.
2235		 */
2236		if (!con_dev) {
2237			con_dev = fwnode_get_next_parent_dev(link->consumer);
2238			/*
2239			 * However, if the consumer's parent device is also the
2240			 * parent of the supplier, don't create a
2241			 * consumer-supplier link from the parent to its child
2242			 * device. Such a dependency is impossible.
2243			 */
2244			if (con_dev &&
2245			    fwnode_is_ancestor_of(con_dev->fwnode, fwnode)) {
2246				put_device(con_dev);
2247				con_dev = NULL;
2248			} else {
2249				own_link = false;
2250			}
2251		}
2252
2253		if (!con_dev)
2254			continue;
2255
2256		ret = fw_devlink_create_devlink(con_dev, fwnode, link);
2257		put_device(con_dev);
2258		if (!own_link || ret == -EAGAIN)
2259			continue;
2260
2261		__fwnode_link_del(link);
2262	}
2263}
2264
2265/**
2266 * __fw_devlink_link_to_suppliers - Create device links to suppliers of a device
2267 * @dev: The consumer device that needs to be linked to its suppliers
2268 * @fwnode: Root of the fwnode tree that is used to create device links
2269 *
2270 * This function looks at all the supplier fwnodes of fwnode tree rooted at
2271 * @fwnode and creates device links between @dev (consumer) and all the
2272 * supplier devices of the entire fwnode tree at @fwnode.
2273 *
2274 * The function creates normal (non-SYNC_STATE_ONLY) device links between @dev
2275 * and the real suppliers of @dev. Once these device links are created, the
2276 * fwnode links are deleted.
2277 *
2278 * In addition, it also looks at all the suppliers of the entire fwnode tree
2279 * because some of the child devices of @dev that have not been added yet
2280 * (because @dev hasn't probed) might already have their suppliers added to
2281 * driver core. So, this function creates SYNC_STATE_ONLY device links between
2282 * @dev (consumer) and these suppliers to make sure they don't execute their
2283 * sync_state() callbacks before these child devices have a chance to create
2284 * their device links. The fwnode links that correspond to the child devices
2285 * aren't delete because they are needed later to create the device links
2286 * between the real consumer and supplier devices.
2287 */
2288static void __fw_devlink_link_to_suppliers(struct device *dev,
2289					   struct fwnode_handle *fwnode)
2290{
2291	bool own_link = (dev->fwnode == fwnode);
2292	struct fwnode_link *link, *tmp;
2293	struct fwnode_handle *child = NULL;
2294
2295	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) {
2296		int ret;
2297		struct fwnode_handle *sup = link->supplier;
2298
2299		ret = fw_devlink_create_devlink(dev, sup, link);
2300		if (!own_link || ret == -EAGAIN)
2301			continue;
2302
2303		__fwnode_link_del(link);
2304	}
2305
2306	/*
2307	 * Make "proxy" SYNC_STATE_ONLY device links to represent the needs of
2308	 * all the descendants. This proxy link step is needed to handle the
2309	 * case where the supplier is added before the consumer's parent device
2310	 * (@dev).
2311	 */
2312	while ((child = fwnode_get_next_available_child_node(fwnode, child)))
2313		__fw_devlink_link_to_suppliers(dev, child);
2314}
2315
2316static void fw_devlink_link_device(struct device *dev)
2317{
2318	struct fwnode_handle *fwnode = dev->fwnode;
2319
2320	if (!fw_devlink_flags)
2321		return;
2322
2323	fw_devlink_parse_fwtree(fwnode);
2324
2325	guard(mutex)(&fwnode_link_lock);
2326
2327	__fw_devlink_link_to_consumers(dev);
2328	__fw_devlink_link_to_suppliers(dev, fwnode);
2329}
2330
2331/* Device links support end. */
2332
2333static struct kobject *dev_kobj;
2334
2335/* /sys/dev/char */
2336static struct kobject *sysfs_dev_char_kobj;
2337
2338/* /sys/dev/block */
2339static struct kobject *sysfs_dev_block_kobj;
2340
2341static DEFINE_MUTEX(device_hotplug_lock);
2342
2343void lock_device_hotplug(void)
2344{
2345	mutex_lock(&device_hotplug_lock);
2346}
2347
2348void unlock_device_hotplug(void)
2349{
2350	mutex_unlock(&device_hotplug_lock);
2351}
2352
2353int lock_device_hotplug_sysfs(void)
2354{
2355	if (mutex_trylock(&device_hotplug_lock))
2356		return 0;
2357
2358	/* Avoid busy looping (5 ms of sleep should do). */
2359	msleep(5);
2360	return restart_syscall();
2361}
2362
2363#ifdef CONFIG_BLOCK
2364static inline int device_is_not_partition(struct device *dev)
2365{
2366	return !(dev->type == &part_type);
2367}
2368#else
2369static inline int device_is_not_partition(struct device *dev)
2370{
2371	return 1;
2372}
2373#endif
2374
2375static void device_platform_notify(struct device *dev)
2376{
2377	acpi_device_notify(dev);
2378
2379	software_node_notify(dev);
2380}
2381
2382static void device_platform_notify_remove(struct device *dev)
2383{
2384	software_node_notify_remove(dev);
2385
2386	acpi_device_notify_remove(dev);
2387}
2388
2389/**
2390 * dev_driver_string - Return a device's driver name, if at all possible
2391 * @dev: struct device to get the name of
2392 *
2393 * Will return the device's driver's name if it is bound to a device.  If
2394 * the device is not bound to a driver, it will return the name of the bus
2395 * it is attached to.  If it is not attached to a bus either, an empty
2396 * string will be returned.
2397 */
2398const char *dev_driver_string(const struct device *dev)
2399{
2400	struct device_driver *drv;
2401
2402	/* dev->driver can change to NULL underneath us because of unbinding,
2403	 * so be careful about accessing it.  dev->bus and dev->class should
2404	 * never change once they are set, so they don't need special care.
2405	 */
2406	drv = READ_ONCE(dev->driver);
2407	return drv ? drv->name : dev_bus_name(dev);
2408}
2409EXPORT_SYMBOL(dev_driver_string);
2410
2411#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
2412
2413static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
2414			     char *buf)
2415{
2416	struct device_attribute *dev_attr = to_dev_attr(attr);
2417	struct device *dev = kobj_to_dev(kobj);
2418	ssize_t ret = -EIO;
2419
2420	if (dev_attr->show)
2421		ret = dev_attr->show(dev, dev_attr, buf);
2422	if (ret >= (ssize_t)PAGE_SIZE) {
2423		printk("dev_attr_show: %pS returned bad count\n",
2424				dev_attr->show);
2425	}
2426	return ret;
2427}
2428
2429static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
2430			      const char *buf, size_t count)
2431{
2432	struct device_attribute *dev_attr = to_dev_attr(attr);
2433	struct device *dev = kobj_to_dev(kobj);
2434	ssize_t ret = -EIO;
2435
2436	if (dev_attr->store)
2437		ret = dev_attr->store(dev, dev_attr, buf, count);
2438	return ret;
2439}
2440
2441static const struct sysfs_ops dev_sysfs_ops = {
2442	.show	= dev_attr_show,
2443	.store	= dev_attr_store,
2444};
2445
2446#define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
2447
2448ssize_t device_store_ulong(struct device *dev,
2449			   struct device_attribute *attr,
2450			   const char *buf, size_t size)
2451{
2452	struct dev_ext_attribute *ea = to_ext_attr(attr);
2453	int ret;
2454	unsigned long new;
2455
2456	ret = kstrtoul(buf, 0, &new);
2457	if (ret)
2458		return ret;
2459	*(unsigned long *)(ea->var) = new;
2460	/* Always return full write size even if we didn't consume all */
2461	return size;
2462}
2463EXPORT_SYMBOL_GPL(device_store_ulong);
2464
2465ssize_t device_show_ulong(struct device *dev,
2466			  struct device_attribute *attr,
2467			  char *buf)
2468{
2469	struct dev_ext_attribute *ea = to_ext_attr(attr);
2470	return sysfs_emit(buf, "%lx\n", *(unsigned long *)(ea->var));
2471}
2472EXPORT_SYMBOL_GPL(device_show_ulong);
2473
2474ssize_t device_store_int(struct device *dev,
2475			 struct device_attribute *attr,
2476			 const char *buf, size_t size)
2477{
2478	struct dev_ext_attribute *ea = to_ext_attr(attr);
2479	int ret;
2480	long new;
2481
2482	ret = kstrtol(buf, 0, &new);
2483	if (ret)
2484		return ret;
2485
2486	if (new > INT_MAX || new < INT_MIN)
2487		return -EINVAL;
2488	*(int *)(ea->var) = new;
2489	/* Always return full write size even if we didn't consume all */
2490	return size;
2491}
2492EXPORT_SYMBOL_GPL(device_store_int);
2493
2494ssize_t device_show_int(struct device *dev,
2495			struct device_attribute *attr,
2496			char *buf)
2497{
2498	struct dev_ext_attribute *ea = to_ext_attr(attr);
2499
2500	return sysfs_emit(buf, "%d\n", *(int *)(ea->var));
2501}
2502EXPORT_SYMBOL_GPL(device_show_int);
2503
2504ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
2505			  const char *buf, size_t size)
2506{
2507	struct dev_ext_attribute *ea = to_ext_attr(attr);
2508
2509	if (kstrtobool(buf, ea->var) < 0)
2510		return -EINVAL;
2511
2512	return size;
2513}
2514EXPORT_SYMBOL_GPL(device_store_bool);
2515
2516ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
2517			 char *buf)
2518{
2519	struct dev_ext_attribute *ea = to_ext_attr(attr);
2520
2521	return sysfs_emit(buf, "%d\n", *(bool *)(ea->var));
2522}
2523EXPORT_SYMBOL_GPL(device_show_bool);
2524
2525ssize_t device_show_string(struct device *dev,
2526			   struct device_attribute *attr, char *buf)
2527{
2528	struct dev_ext_attribute *ea = to_ext_attr(attr);
2529
2530	return sysfs_emit(buf, "%s\n", (char *)ea->var);
2531}
2532EXPORT_SYMBOL_GPL(device_show_string);
2533
2534/**
2535 * device_release - free device structure.
2536 * @kobj: device's kobject.
2537 *
2538 * This is called once the reference count for the object
2539 * reaches 0. We forward the call to the device's release
2540 * method, which should handle actually freeing the structure.
2541 */
2542static void device_release(struct kobject *kobj)
2543{
2544	struct device *dev = kobj_to_dev(kobj);
2545	struct device_private *p = dev->p;
2546
2547	/*
2548	 * Some platform devices are driven without driver attached
2549	 * and managed resources may have been acquired.  Make sure
2550	 * all resources are released.
2551	 *
2552	 * Drivers still can add resources into device after device
2553	 * is deleted but alive, so release devres here to avoid
2554	 * possible memory leak.
2555	 */
2556	devres_release_all(dev);
2557
2558	kfree(dev->dma_range_map);
2559	kfree(dev->driver_override.name);
2560
2561	if (dev->release)
2562		dev->release(dev);
2563	else if (dev->type && dev->type->release)
2564		dev->type->release(dev);
2565	else if (dev->class && dev->class->dev_release)
2566		dev->class->dev_release(dev);
2567	else
2568		WARN(1, KERN_ERR "Device '%s' does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
2569			dev_name(dev));
2570	kfree(p);
2571}
2572
2573static const void *device_namespace(const struct kobject *kobj)
2574{
2575	const struct device *dev = kobj_to_dev(kobj);
2576	const void *ns = NULL;
2577
2578	if (dev->class && dev->class->namespace)
2579		ns = dev->class->namespace(dev);
2580
2581	return ns;
2582}
2583
2584static void device_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
2585{
2586	const struct device *dev = kobj_to_dev(kobj);
2587
2588	if (dev->class && dev->class->get_ownership)
2589		dev->class->get_ownership(dev, uid, gid);
2590}
2591
2592static const struct kobj_type device_ktype = {
2593	.release	= device_release,
2594	.sysfs_ops	= &dev_sysfs_ops,
2595	.namespace	= device_namespace,
2596	.get_ownership	= device_get_ownership,
2597};
2598
2599
2600static int dev_uevent_filter(const struct kobject *kobj)
2601{
2602	const struct kobj_type *ktype = get_ktype(kobj);
2603
2604	if (ktype == &device_ktype) {
2605		const struct device *dev = kobj_to_dev(kobj);
2606		if (dev->bus)
2607			return 1;
2608		if (dev->class)
2609			return 1;
2610	}
2611	return 0;
2612}
2613
2614static const char *dev_uevent_name(const struct kobject *kobj)
2615{
2616	const struct device *dev = kobj_to_dev(kobj);
2617
2618	if (dev->bus)
2619		return dev->bus->name;
2620	if (dev->class)
2621		return dev->class->name;
2622	return NULL;
2623}
2624
2625/*
2626 * Try filling "DRIVER=<name>" uevent variable for a device. Because this
2627 * function may race with binding and unbinding the device from a driver,
2628 * we need to be careful. Binding is generally safe, at worst we miss the
2629 * fact that the device is already bound to a driver (but the driver
2630 * information that is delivered through uevents is best-effort, it may
2631 * become obsolete as soon as it is generated anyways). Unbinding is more
2632 * risky as driver pointer is transitioning to NULL, so READ_ONCE() should
2633 * be used to make sure we are dealing with the same pointer, and to
2634 * ensure that driver structure is not going to disappear from under us
2635 * we take bus' drivers klist lock. The assumption that only registered
2636 * driver can be bound to a device, and to unregister a driver bus code
2637 * will take the same lock.
2638 */
2639static void dev_driver_uevent(const struct device *dev, struct kobj_uevent_env *env)
2640{
2641	struct subsys_private *sp = bus_to_subsys(dev->bus);
2642
2643	if (sp) {
2644		scoped_guard(spinlock, &sp->klist_drivers.k_lock) {
2645			struct device_driver *drv = READ_ONCE(dev->driver);
2646			if (drv)
2647				add_uevent_var(env, "DRIVER=%s", drv->name);
2648		}
2649
2650		subsys_put(sp);
2651	}
2652}
2653
2654static int dev_uevent(const struct kobject *kobj, struct kobj_uevent_env *env)
2655{
2656	const struct device *dev = kobj_to_dev(kobj);
2657	int retval = 0;
2658
2659	/* add device node properties if present */
2660	if (MAJOR(dev->devt)) {
2661		const char *tmp;
2662		const char *name;
2663		umode_t mode = 0;
2664		kuid_t uid = GLOBAL_ROOT_UID;
2665		kgid_t gid = GLOBAL_ROOT_GID;
2666
2667		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
2668		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
2669		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
2670		if (name) {
2671			add_uevent_var(env, "DEVNAME=%s", name);
2672			if (mode)
2673				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
2674			if (!uid_eq(uid, GLOBAL_ROOT_UID))
2675				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
2676			if (!gid_eq(gid, GLOBAL_ROOT_GID))
2677				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
2678			kfree(tmp);
2679		}
2680	}
2681
2682	if (dev->type && dev->type->name)
2683		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
2684
2685	/* Add "DRIVER=%s" variable if the device is bound to a driver */
2686	dev_driver_uevent(dev, env);
2687
2688	/* Add common DT information about the device */
2689	of_device_uevent(dev, env);
2690
2691	/* have the bus specific function add its stuff */
2692	if (dev->bus && dev->bus->uevent) {
2693		retval = dev->bus->uevent(dev, env);
2694		if (retval)
2695			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
2696				 dev_name(dev), __func__, retval);
2697	}
2698
2699	/* have the class specific function add its stuff */
2700	if (dev->class && dev->class->dev_uevent) {
2701		retval = dev->class->dev_uevent(dev, env);
2702		if (retval)
2703			pr_debug("device: '%s': %s: class uevent() "
2704				 "returned %d\n", dev_name(dev),
2705				 __func__, retval);
2706	}
2707
2708	/* have the device type specific function add its stuff */
2709	if (dev->type && dev->type->uevent) {
2710		retval = dev->type->uevent(dev, env);
2711		if (retval)
2712			pr_debug("device: '%s': %s: dev_type uevent() "
2713				 "returned %d\n", dev_name(dev),
2714				 __func__, retval);
2715	}
2716
2717	return retval;
2718}
2719
2720static const struct kset_uevent_ops device_uevent_ops = {
2721	.filter =	dev_uevent_filter,
2722	.name =		dev_uevent_name,
2723	.uevent =	dev_uevent,
2724};
2725
2726static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
2727			   char *buf)
2728{
2729	struct kobject *top_kobj;
2730	struct kset *kset;
2731	struct kobj_uevent_env *env = NULL;
2732	int i;
2733	int len = 0;
2734	int retval;
2735
2736	/* search the kset, the device belongs to */
2737	top_kobj = &dev->kobj;
2738	while (!top_kobj->kset && top_kobj->parent)
2739		top_kobj = top_kobj->parent;
2740	if (!top_kobj->kset)
2741		goto out;
2742
2743	kset = top_kobj->kset;
2744	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
2745		goto out;
2746
2747	/* respect filter */
2748	if (kset->uevent_ops && kset->uevent_ops->filter)
2749		if (!kset->uevent_ops->filter(&dev->kobj))
2750			goto out;
2751
2752	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
2753	if (!env)
2754		return -ENOMEM;
2755
2756	/* let the kset specific function add its keys */
2757	retval = kset->uevent_ops->uevent(&dev->kobj, env);
2758	if (retval)
2759		goto out;
2760
2761	/* copy keys to file */
2762	for (i = 0; i < env->envp_idx; i++)
2763		len += sysfs_emit_at(buf, len, "%s\n", env->envp[i]);
2764out:
2765	kfree(env);
2766	return len;
2767}
2768
2769static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
2770			    const char *buf, size_t count)
2771{
2772	int rc;
2773
2774	rc = kobject_synth_uevent(&dev->kobj, buf, count);
2775
2776	if (rc) {
2777		dev_err(dev, "uevent: failed to send synthetic uevent: %d\n", rc);
2778		return rc;
2779	}
2780
2781	return count;
2782}
2783static DEVICE_ATTR_RW(uevent);
2784
2785static ssize_t online_show(struct device *dev, struct device_attribute *attr,
2786			   char *buf)
2787{
2788	bool val;
2789
2790	device_lock(dev);
2791	val = !dev->offline;
2792	device_unlock(dev);
2793	return sysfs_emit(buf, "%u\n", val);
2794}
2795
2796static ssize_t online_store(struct device *dev, struct device_attribute *attr,
2797			    const char *buf, size_t count)
2798{
2799	bool val;
2800	int ret;
2801
2802	ret = kstrtobool(buf, &val);
2803	if (ret < 0)
2804		return ret;
2805
2806	ret = lock_device_hotplug_sysfs();
2807	if (ret)
2808		return ret;
2809
2810	ret = val ? device_online(dev) : device_offline(dev);
2811	unlock_device_hotplug();
2812	return ret < 0 ? ret : count;
2813}
2814static DEVICE_ATTR_RW(online);
2815
2816static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
2817			      char *buf)
2818{
2819	const char *loc;
2820
2821	switch (dev->removable) {
2822	case DEVICE_REMOVABLE:
2823		loc = "removable";
2824		break;
2825	case DEVICE_FIXED:
2826		loc = "fixed";
2827		break;
2828	default:
2829		loc = "unknown";
2830	}
2831	return sysfs_emit(buf, "%s\n", loc);
2832}
2833static DEVICE_ATTR_RO(removable);
2834
2835int device_add_groups(struct device *dev, const struct attribute_group **groups)
2836{
2837	return sysfs_create_groups(&dev->kobj, groups);
2838}
2839EXPORT_SYMBOL_GPL(device_add_groups);
2840
2841void device_remove_groups(struct device *dev,
2842			  const struct attribute_group **groups)
2843{
2844	sysfs_remove_groups(&dev->kobj, groups);
2845}
2846EXPORT_SYMBOL_GPL(device_remove_groups);
2847
2848union device_attr_group_devres {
2849	const struct attribute_group *group;
2850	const struct attribute_group **groups;
2851};
2852
2853static void devm_attr_group_remove(struct device *dev, void *res)
2854{
2855	union device_attr_group_devres *devres = res;
2856	const struct attribute_group *group = devres->group;
2857
2858	dev_dbg(dev, "%s: removing group %p\n", __func__, group);
2859	sysfs_remove_group(&dev->kobj, group);
2860}
2861
2862/**
2863 * devm_device_add_group - given a device, create a managed attribute group
2864 * @dev:	The device to create the group for
2865 * @grp:	The attribute group to create
2866 *
2867 * This function creates a group for the first time.  It will explicitly
2868 * warn and error if any of the attribute files being created already exist.
2869 *
2870 * Returns 0 on success or error code on failure.
2871 */
2872int devm_device_add_group(struct device *dev, const struct attribute_group *grp)
2873{
2874	union device_attr_group_devres *devres;
2875	int error;
2876
2877	devres = devres_alloc(devm_attr_group_remove,
2878			      sizeof(*devres), GFP_KERNEL);
2879	if (!devres)
2880		return -ENOMEM;
2881
2882	error = sysfs_create_group(&dev->kobj, grp);
2883	if (error) {
2884		devres_free(devres);
2885		return error;
2886	}
2887
2888	devres->group = grp;
2889	devres_add(dev, devres);
2890	return 0;
2891}
2892EXPORT_SYMBOL_GPL(devm_device_add_group);
2893
2894static int device_add_attrs(struct device *dev)
2895{
2896	const struct class *class = dev->class;
2897	const struct device_type *type = dev->type;
2898	int error;
2899
2900	if (class) {
2901		error = device_add_groups(dev, class->dev_groups);
2902		if (error)
2903			return error;
2904	}
2905
2906	if (type) {
2907		error = device_add_groups(dev, type->groups);
2908		if (error)
2909			goto err_remove_class_groups;
2910	}
2911
2912	error = device_add_groups(dev, dev->groups);
2913	if (error)
2914		goto err_remove_type_groups;
2915
2916	if (device_supports_offline(dev) && !dev->offline_disabled) {
2917		error = device_create_file(dev, &dev_attr_online);
2918		if (error)
2919			goto err_remove_dev_groups;
2920	}
2921
2922	if (fw_devlink_flags && !fw_devlink_is_permissive() && dev->fwnode) {
2923		error = device_create_file(dev, &dev_attr_waiting_for_supplier);
2924		if (error)
2925			goto err_remove_dev_online;
2926	}
2927
2928	if (dev_removable_is_valid(dev)) {
2929		error = device_create_file(dev, &dev_attr_removable);
2930		if (error)
2931			goto err_remove_dev_waiting_for_supplier;
2932	}
2933
2934	if (dev_add_physical_location(dev)) {
2935		error = device_add_group(dev,
2936			&dev_attr_physical_location_group);
2937		if (error)
2938			goto err_remove_dev_removable;
2939	}
2940
2941	return 0;
2942
2943 err_remove_dev_removable:
2944	device_remove_file(dev, &dev_attr_removable);
2945 err_remove_dev_waiting_for_supplier:
2946	device_remove_file(dev, &dev_attr_waiting_for_supplier);
2947 err_remove_dev_online:
2948	device_remove_file(dev, &dev_attr_online);
2949 err_remove_dev_groups:
2950	device_remove_groups(dev, dev->groups);
2951 err_remove_type_groups:
2952	if (type)
2953		device_remove_groups(dev, type->groups);
2954 err_remove_class_groups:
2955	if (class)
2956		device_remove_groups(dev, class->dev_groups);
2957
2958	return error;
2959}
2960
2961static void device_remove_attrs(struct device *dev)
2962{
2963	const struct class *class = dev->class;
2964	const struct device_type *type = dev->type;
2965
2966	if (dev->physical_location) {
2967		device_remove_group(dev, &dev_attr_physical_location_group);
2968		kfree(dev->physical_location);
2969	}
2970
2971	device_remove_file(dev, &dev_attr_removable);
2972	device_remove_file(dev, &dev_attr_waiting_for_supplier);
2973	device_remove_file(dev, &dev_attr_online);
2974	device_remove_groups(dev, dev->groups);
2975
2976	if (type)
2977		device_remove_groups(dev, type->groups);
2978
2979	if (class)
2980		device_remove_groups(dev, class->dev_groups);
2981}
2982
2983static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
2984			char *buf)
2985{
2986	return print_dev_t(buf, dev->devt);
2987}
2988static DEVICE_ATTR_RO(dev);
2989
2990/* /sys/devices/ */
2991struct kset *devices_kset;
2992
2993/**
2994 * devices_kset_move_before - Move device in the devices_kset's list.
2995 * @deva: Device to move.
2996 * @devb: Device @deva should come before.
2997 */
2998static void devices_kset_move_before(struct device *deva, struct device *devb)
2999{
3000	if (!devices_kset)
3001		return;
3002	pr_debug("devices_kset: Moving %s before %s\n",
3003		 dev_name(deva), dev_name(devb));
3004	spin_lock(&devices_kset->list_lock);
3005	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
3006	spin_unlock(&devices_kset->list_lock);
3007}
3008
3009/**
3010 * devices_kset_move_after - Move device in the devices_kset's list.
3011 * @deva: Device to move
3012 * @devb: Device @deva should come after.
3013 */
3014static void devices_kset_move_after(struct device *deva, struct device *devb)
3015{
3016	if (!devices_kset)
3017		return;
3018	pr_debug("devices_kset: Moving %s after %s\n",
3019		 dev_name(deva), dev_name(devb));
3020	spin_lock(&devices_kset->list_lock);
3021	list_move(&deva->kobj.entry, &devb->kobj.entry);
3022	spin_unlock(&devices_kset->list_lock);
3023}
3024
3025/**
3026 * devices_kset_move_last - move the device to the end of devices_kset's list.
3027 * @dev: device to move
3028 */
3029void devices_kset_move_last(struct device *dev)
3030{
3031	if (!devices_kset)
3032		return;
3033	pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
3034	spin_lock(&devices_kset->list_lock);
3035	list_move_tail(&dev->kobj.entry, &devices_kset->list);
3036	spin_unlock(&devices_kset->list_lock);
3037}
3038
3039/**
3040 * device_create_file - create sysfs attribute file for device.
3041 * @dev: device.
3042 * @attr: device attribute descriptor.
3043 */
3044int device_create_file(struct device *dev,
3045		       const struct device_attribute *attr)
3046{
3047	int error = 0;
3048
3049	if (dev) {
3050		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
3051			"Attribute %s: write permission without 'store'\n",
3052			attr->attr.name);
3053		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
3054			"Attribute %s: read permission without 'show'\n",
3055			attr->attr.name);
3056		error = sysfs_create_file(&dev->kobj, &attr->attr);
3057	}
3058
3059	return error;
3060}
3061EXPORT_SYMBOL_GPL(device_create_file);
3062
3063/**
3064 * device_remove_file - remove sysfs attribute file.
3065 * @dev: device.
3066 * @attr: device attribute descriptor.
3067 */
3068void device_remove_file(struct device *dev,
3069			const struct device_attribute *attr)
3070{
3071	if (dev)
3072		sysfs_remove_file(&dev->kobj, &attr->attr);
3073}
3074EXPORT_SYMBOL_GPL(device_remove_file);
3075
3076/**
3077 * device_remove_file_self - remove sysfs attribute file from its own method.
3078 * @dev: device.
3079 * @attr: device attribute descriptor.
3080 *
3081 * See kernfs_remove_self() for details.
3082 */
3083bool device_remove_file_self(struct device *dev,
3084			     const struct device_attribute *attr)
3085{
3086	if (dev)
3087		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
3088	else
3089		return false;
3090}
3091EXPORT_SYMBOL_GPL(device_remove_file_self);
3092
3093/**
3094 * device_create_bin_file - create sysfs binary attribute file for device.
3095 * @dev: device.
3096 * @attr: device binary attribute descriptor.
3097 */
3098int device_create_bin_file(struct device *dev,
3099			   const struct bin_attribute *attr)
3100{
3101	int error = -EINVAL;
3102	if (dev)
3103		error = sysfs_create_bin_file(&dev->kobj, attr);
3104	return error;
3105}
3106EXPORT_SYMBOL_GPL(device_create_bin_file);
3107
3108/**
3109 * device_remove_bin_file - remove sysfs binary attribute file
3110 * @dev: device.
3111 * @attr: device binary attribute descriptor.
3112 */
3113void device_remove_bin_file(struct device *dev,
3114			    const struct bin_attribute *attr)
3115{
3116	if (dev)
3117		sysfs_remove_bin_file(&dev->kobj, attr);
3118}
3119EXPORT_SYMBOL_GPL(device_remove_bin_file);
3120
3121static void klist_children_get(struct klist_node *n)
3122{
3123	struct device_private *p = to_device_private_parent(n);
3124	struct device *dev = p->device;
3125
3126	get_device(dev);
3127}
3128
3129static void klist_children_put(struct klist_node *n)
3130{
3131	struct device_private *p = to_device_private_parent(n);
3132	struct device *dev = p->device;
3133
3134	put_device(dev);
3135}
3136
3137/**
3138 * device_initialize - init device structure.
3139 * @dev: device.
3140 *
3141 * This prepares the device for use by other layers by initializing
3142 * its fields.
3143 * It is the first half of device_register(), if called by
3144 * that function, though it can also be called separately, so one
3145 * may use @dev's fields. In particular, get_device()/put_device()
3146 * may be used for reference counting of @dev after calling this
3147 * function.
3148 *
3149 * All fields in @dev must be initialized by the caller to 0, except
3150 * for those explicitly set to some other value.  The simplest
3151 * approach is to use kzalloc() to allocate the structure containing
3152 * @dev.
3153 *
3154 * NOTE: Use put_device() to give up your reference instead of freeing
3155 * @dev directly once you have called this function.
3156 */
3157void device_initialize(struct device *dev)
3158{
3159	dev->kobj.kset = devices_kset;
3160	kobject_init(&dev->kobj, &device_ktype);
3161	INIT_LIST_HEAD(&dev->dma_pools);
3162	mutex_init(&dev->mutex);
3163	spin_lock_init(&dev->driver_override.lock);
3164	lockdep_set_novalidate_class(&dev->mutex);
3165	spin_lock_init(&dev->devres_lock);
3166	INIT_LIST_HEAD(&dev->devres_head);
3167	device_pm_init(dev);
3168	set_dev_node(dev, NUMA_NO_NODE);
3169	INIT_LIST_HEAD(&dev->links.consumers);
3170	INIT_LIST_HEAD(&dev->links.suppliers);
3171	INIT_LIST_HEAD(&dev->links.defer_sync);
3172	dev->links.status = DL_DEV_NO_DRIVER;
3173#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
3174    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
3175    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
3176	dev->dma_coherent = dma_default_coherent;
3177#endif
3178	swiotlb_dev_init(dev);
3179}
3180EXPORT_SYMBOL_GPL(device_initialize);
3181
3182struct kobject *virtual_device_parent(void)
3183{
3184	static struct kobject *virtual_dir = NULL;
3185
3186	if (!virtual_dir)
3187		virtual_dir = kobject_create_and_add("virtual",
3188						     &devices_kset->kobj);
3189
3190	return virtual_dir;
3191}
3192
3193struct class_dir {
3194	struct kobject kobj;
3195	const struct class *class;
3196};
3197
3198#define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
3199
3200static void class_dir_release(struct kobject *kobj)
3201{
3202	struct class_dir *dir = to_class_dir(kobj);
3203	kfree(dir);
3204}
3205
3206static const
3207struct kobj_ns_type_operations *class_dir_child_ns_type(const struct kobject *kobj)
3208{
3209	const struct class_dir *dir = to_class_dir(kobj);
3210	return dir->class->ns_type;
3211}
3212
3213static const struct kobj_type class_dir_ktype = {
3214	.release	= class_dir_release,
3215	.sysfs_ops	= &kobj_sysfs_ops,
3216	.child_ns_type	= class_dir_child_ns_type
3217};
3218
3219static struct kobject *class_dir_create_and_add(struct subsys_private *sp,
3220						struct kobject *parent_kobj)
3221{
3222	struct class_dir *dir;
3223	int retval;
3224
3225	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
3226	if (!dir)
3227		return ERR_PTR(-ENOMEM);
3228
3229	dir->class = sp->class;
3230	kobject_init(&dir->kobj, &class_dir_ktype);
3231
3232	dir->kobj.kset = &sp->glue_dirs;
3233
3234	retval = kobject_add(&dir->kobj, parent_kobj, "%s", sp->class->name);
3235	if (retval < 0) {
3236		kobject_put(&dir->kobj);
3237		return ERR_PTR(retval);
3238	}
3239	return &dir->kobj;
3240}
3241
3242static DEFINE_MUTEX(gdp_mutex);
3243
3244static struct kobject *get_device_parent(struct device *dev,
3245					 struct device *parent)
3246{
3247	struct subsys_private *sp = class_to_subsys(dev->class);
3248	struct kobject *kobj = NULL;
3249
3250	if (sp) {
3251		struct kobject *parent_kobj;
3252		struct kobject *k;
3253
3254		/*
3255		 * If we have no parent, we live in "virtual".
3256		 * Class-devices with a non class-device as parent, live
3257		 * in a "glue" directory to prevent namespace collisions.
3258		 */
3259		if (parent == NULL)
3260			parent_kobj = virtual_device_parent();
3261		else if (parent->class && !dev->class->ns_type) {
3262			subsys_put(sp);
3263			return &parent->kobj;
3264		} else {
3265			parent_kobj = &parent->kobj;
3266		}
3267
3268		mutex_lock(&gdp_mutex);
3269
3270		/* find our class-directory at the parent and reference it */
3271		spin_lock(&sp->glue_dirs.list_lock);
3272		list_for_each_entry(k, &sp->glue_dirs.list, entry)
3273			if (k->parent == parent_kobj) {
3274				kobj = kobject_get(k);
3275				break;
3276			}
3277		spin_unlock(&sp->glue_dirs.list_lock);
3278		if (kobj) {
3279			mutex_unlock(&gdp_mutex);
3280			subsys_put(sp);
3281			return kobj;
3282		}
3283
3284		/* or create a new class-directory at the parent device */
3285		k = class_dir_create_and_add(sp, parent_kobj);
3286		/* do not emit an uevent for this simple "glue" directory */
3287		mutex_unlock(&gdp_mutex);
3288		subsys_put(sp);
3289		return k;
3290	}
3291
3292	/* subsystems can specify a default root directory for their devices */
3293	if (!parent && dev->bus) {
3294		struct device *dev_root = bus_get_dev_root(dev->bus);
3295
3296		if (dev_root) {
3297			kobj = &dev_root->kobj;
3298			put_device(dev_root);
3299			return kobj;
3300		}
3301	}
3302
3303	if (parent)
3304		return &parent->kobj;
3305	return NULL;
3306}
3307
3308static inline bool live_in_glue_dir(struct kobject *kobj,
3309				    struct device *dev)
3310{
3311	struct subsys_private *sp;
3312	bool retval;
3313
3314	if (!kobj || !dev->class)
3315		return false;
3316
3317	sp = class_to_subsys(dev->class);
3318	if (!sp)
3319		return false;
3320
3321	if (kobj->kset == &sp->glue_dirs)
3322		retval = true;
3323	else
3324		retval = false;
3325
3326	subsys_put(sp);
3327	return retval;
3328}
3329
3330static inline struct kobject *get_glue_dir(struct device *dev)
3331{
3332	return dev->kobj.parent;
3333}
3334
3335/**
3336 * kobject_has_children - Returns whether a kobject has children.
3337 * @kobj: the object to test
3338 *
3339 * This will return whether a kobject has other kobjects as children.
3340 *
3341 * It does NOT account for the presence of attribute files, only sub
3342 * directories. It also assumes there is no concurrent addition or
3343 * removal of such children, and thus relies on external locking.
3344 */
3345static inline bool kobject_has_children(struct kobject *kobj)
3346{
3347	WARN_ON_ONCE(kref_read(&kobj->kref) == 0);
3348
3349	return kobj->sd && kobj->sd->dir.subdirs;
3350}
3351
3352/*
3353 * make sure cleaning up dir as the last step, we need to make
3354 * sure .release handler of kobject is run with holding the
3355 * global lock
3356 */
3357static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
3358{
3359	unsigned int ref;
3360
3361	/* see if we live in a "glue" directory */
3362	if (!live_in_glue_dir(glue_dir, dev))
3363		return;
3364
3365	mutex_lock(&gdp_mutex);
3366	/**
3367	 * There is a race condition between removing glue directory
3368	 * and adding a new device under the glue directory.
3369	 *
3370	 * CPU1:                                         CPU2:
3371	 *
3372	 * device_add()
3373	 *   get_device_parent()
3374	 *     class_dir_create_and_add()
3375	 *       kobject_add_internal()
3376	 *         create_dir()    // create glue_dir
3377	 *
3378	 *                                               device_add()
3379	 *                                                 get_device_parent()
3380	 *                                                   kobject_get() // get glue_dir
3381	 *
3382	 * device_del()
3383	 *   cleanup_glue_dir()
3384	 *     kobject_del(glue_dir)
3385	 *
3386	 *                                               kobject_add()
3387	 *                                                 kobject_add_internal()
3388	 *                                                   create_dir() // in glue_dir
3389	 *                                                     sysfs_create_dir_ns()
3390	 *                                                       kernfs_create_dir_ns(sd)
3391	 *
3392	 *       sysfs_remove_dir() // glue_dir->sd=NULL
3393	 *       sysfs_put()        // free glue_dir->sd
3394	 *
3395	 *                                                         // sd is freed
3396	 *                                                         kernfs_new_node(sd)
3397	 *                                                           kernfs_get(glue_dir)
3398	 *                                                           kernfs_add_one()
3399	 *                                                           kernfs_put()
3400	 *
3401	 * Before CPU1 remove last child device under glue dir, if CPU2 add
3402	 * a new device under glue dir, the glue_dir kobject reference count
3403	 * will be increase to 2 in kobject_get(k). And CPU2 has been called
3404	 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
3405	 * and sysfs_put(). This result in glue_dir->sd is freed.
3406	 *
3407	 * Then the CPU2 will see a stale "empty" but still potentially used
3408	 * glue dir around in kernfs_new_node().
3409	 *
3410	 * In order to avoid this happening, we also should make sure that
3411	 * kernfs_node for glue_dir is released in CPU1 only when refcount
3412	 * for glue_dir kobj is 1.
3413	 */
3414	ref = kref_read(&glue_dir->kref);
3415	if (!kobject_has_children(glue_dir) && !--ref)
3416		kobject_del(glue_dir);
3417	kobject_put(glue_dir);
3418	mutex_unlock(&gdp_mutex);
3419}
3420
3421static int device_add_class_symlinks(struct device *dev)
3422{
3423	struct device_node *of_node = dev_of_node(dev);
3424	struct subsys_private *sp;
3425	int error;
3426
3427	if (of_node) {
3428		error = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
3429		if (error)
3430			dev_warn(dev, "Error %d creating of_node link\n",error);
3431		/* An error here doesn't warrant bringing down the device */
3432	}
3433
3434	sp = class_to_subsys(dev->class);
3435	if (!sp)
3436		return 0;
3437
3438	error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
3439	if (error)
3440		goto out_devnode;
3441
3442	if (dev->parent && device_is_not_partition(dev)) {
3443		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
3444					  "device");
3445		if (error)
3446			goto out_subsys;
3447	}
3448
3449	/* link in the class directory pointing to the device */
3450	error = sysfs_create_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3451	if (error)
3452		goto out_device;
3453	goto exit;
3454
3455out_device:
3456	sysfs_remove_link(&dev->kobj, "device");
3457out_subsys:
3458	sysfs_remove_link(&dev->kobj, "subsystem");
3459out_devnode:
3460	sysfs_remove_link(&dev->kobj, "of_node");
3461exit:
3462	subsys_put(sp);
3463	return error;
3464}
3465
3466static void device_remove_class_symlinks(struct device *dev)
3467{
3468	struct subsys_private *sp = class_to_subsys(dev->class);
3469
3470	if (dev_of_node(dev))
3471		sysfs_remove_link(&dev->kobj, "of_node");
3472
3473	if (!sp)
3474		return;
3475
3476	if (dev->parent && device_is_not_partition(dev))
3477		sysfs_remove_link(&dev->kobj, "device");
3478	sysfs_remove_link(&dev->kobj, "subsystem");
3479	sysfs_delete_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3480	subsys_put(sp);
3481}
3482
3483/**
3484 * dev_set_name - set a device name
3485 * @dev: device
3486 * @fmt: format string for the device's name
3487 */
3488int dev_set_name(struct device *dev, const char *fmt, ...)
3489{
3490	va_list vargs;
3491	int err;
3492
3493	va_start(vargs, fmt);
3494	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
3495	va_end(vargs);
3496	return err;
3497}
3498EXPORT_SYMBOL_GPL(dev_set_name);
3499
3500/* select a /sys/dev/ directory for the device */
3501static struct kobject *device_to_dev_kobj(struct device *dev)
3502{
3503	if (is_blockdev(dev))
3504		return sysfs_dev_block_kobj;
3505	else
3506		return sysfs_dev_char_kobj;
3507}
3508
3509static int device_create_sys_dev_entry(struct device *dev)
3510{
3511	struct kobject *kobj = device_to_dev_kobj(dev);
3512	int error = 0;
3513	char devt_str[15];
3514
3515	if (kobj) {
3516		format_dev_t(devt_str, dev->devt);
3517		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
3518	}
3519
3520	return error;
3521}
3522
3523static void device_remove_sys_dev_entry(struct device *dev)
3524{
3525	struct kobject *kobj = device_to_dev_kobj(dev);
3526	char devt_str[15];
3527
3528	if (kobj) {
3529		format_dev_t(devt_str, dev->devt);
3530		sysfs_remove_link(kobj, devt_str);
3531	}
3532}
3533
3534static int device_private_init(struct device *dev)
3535{
3536	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
3537	if (!dev->p)
3538		return -ENOMEM;
3539	dev->p->device = dev;
3540	klist_init(&dev->p->klist_children, klist_children_get,
3541		   klist_children_put);
3542	INIT_LIST_HEAD(&dev->p->deferred_probe);
3543	return 0;
3544}
3545
3546/**
3547 * device_add - add device to device hierarchy.
3548 * @dev: device.
3549 *
3550 * This is part 2 of device_register(), though may be called
3551 * separately _iff_ device_initialize() has been called separately.
3552 *
3553 * This adds @dev to the kobject hierarchy via kobject_add(), adds it
3554 * to the global and sibling lists for the device, then
3555 * adds it to the other relevant subsystems of the driver model.
3556 *
3557 * Do not call this routine or device_register() more than once for
3558 * any device structure.  The driver model core is not designed to work
3559 * with devices that get unregistered and then spring back to life.
3560 * (Among other things, it's very hard to guarantee that all references
3561 * to the previous incarnation of @dev have been dropped.)  Allocate
3562 * and register a fresh new struct device instead.
3563 *
3564 * NOTE: _Never_ directly free @dev after calling this function, even
3565 * if it returned an error! Always use put_device() to give up your
3566 * reference instead.
3567 *
3568 * Rule of thumb is: if device_add() succeeds, you should call
3569 * device_del() when you want to get rid of it. If device_add() has
3570 * *not* succeeded, use *only* put_device() to drop the reference
3571 * count.
3572 */
3573int device_add(struct device *dev)
3574{
3575	struct subsys_private *sp;
3576	struct device *parent;
3577	struct kobject *kobj;
3578	struct class_interface *class_intf;
3579	int error = -EINVAL;
3580	struct kobject *glue_dir = NULL;
3581
3582	dev = get_device(dev);
3583	if (!dev)
3584		goto done;
3585
3586	if (!dev->p) {
3587		error = device_private_init(dev);
3588		if (error)
3589			goto done;
3590	}
3591
3592	/*
3593	 * for statically allocated devices, which should all be converted
3594	 * some day, we need to initialize the name. We prevent reading back
3595	 * the name, and force the use of dev_name()
3596	 */
3597	if (dev->init_name) {
3598		error = dev_set_name(dev, "%s", dev->init_name);
3599		dev->init_name = NULL;
3600	}
3601
3602	if (dev_name(dev))
3603		error = 0;
3604	/* subsystems can specify simple device enumeration */
3605	else if (dev->bus && dev->bus->dev_name)
3606		error = dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
3607	else
3608		error = -EINVAL;
3609	if (error)
3610		goto name_error;
3611
3612	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3613
3614	parent = get_device(dev->parent);
3615	kobj = get_device_parent(dev, parent);
3616	if (IS_ERR(kobj)) {
3617		error = PTR_ERR(kobj);
3618		goto parent_error;
3619	}
3620	if (kobj)
3621		dev->kobj.parent = kobj;
3622
3623	/* use parent numa_node */
3624	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
3625		set_dev_node(dev, dev_to_node(parent));
3626
3627	/* first, register with generic layer. */
3628	/* we require the name to be set before, and pass NULL */
3629	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
3630	if (error) {
3631		glue_dir = kobj;
3632		goto Error;
3633	}
3634
3635	/* notify platform of device entry */
3636	device_platform_notify(dev);
3637
3638	error = device_create_file(dev, &dev_attr_uevent);
3639	if (error)
3640		goto attrError;
3641
3642	error = device_add_class_symlinks(dev);
3643	if (error)
3644		goto SymlinkError;
3645	error = device_add_attrs(dev);
3646	if (error)
3647		goto AttrsError;
3648	error = bus_add_device(dev);
3649	if (error)
3650		goto BusError;
3651	error = dpm_sysfs_add(dev);
3652	if (error)
3653		goto DPMError;
3654	device_pm_add(dev);
3655
3656	if (MAJOR(dev->devt)) {
3657		error = device_create_file(dev, &dev_attr_dev);
3658		if (error)
3659			goto DevAttrError;
3660
3661		error = device_create_sys_dev_entry(dev);
3662		if (error)
3663			goto SysEntryError;
3664
3665		devtmpfs_create_node(dev);
3666	}
3667
3668	/* Notify clients of device addition.  This call must come
3669	 * after dpm_sysfs_add() and before kobject_uevent().
3670	 */
3671	bus_notify(dev, BUS_NOTIFY_ADD_DEVICE);
3672	kobject_uevent(&dev->kobj, KOBJ_ADD);
3673
3674	/*
3675	 * Check if any of the other devices (consumers) have been waiting for
3676	 * this device (supplier) to be added so that they can create a device
3677	 * link to it.
3678	 *
3679	 * This needs to happen after device_pm_add() because device_link_add()
3680	 * requires the supplier be registered before it's called.
3681	 *
3682	 * But this also needs to happen before bus_probe_device() to make sure
3683	 * waiting consumers can link to it before the driver is bound to the
3684	 * device and the driver sync_state callback is called for this device.
3685	 */
3686	if (dev->fwnode && !dev->fwnode->dev) {
3687		dev->fwnode->dev = dev;
3688		fw_devlink_link_device(dev);
3689	}
3690
3691	bus_probe_device(dev);
3692
3693	/*
3694	 * If all driver registration is done and a newly added device doesn't
3695	 * match with any driver, don't block its consumers from probing in
3696	 * case the consumer device is able to operate without this supplier.
3697	 */
3698	if (dev->fwnode && fw_devlink_drv_reg_done && !dev->can_match)
3699		fw_devlink_unblock_consumers(dev);
3700
3701	if (parent)
3702		klist_add_tail(&dev->p->knode_parent,
3703			       &parent->p->klist_children);
3704
3705	sp = class_to_subsys(dev->class);
3706	if (sp) {
3707		mutex_lock(&sp->mutex);
3708		/* tie the class to the device */
3709		klist_add_tail(&dev->p->knode_class, &sp->klist_devices);
3710
3711		/* notify any interfaces that the device is here */
3712		list_for_each_entry(class_intf, &sp->interfaces, node)
3713			if (class_intf->add_dev)
3714				class_intf->add_dev(dev);
3715		mutex_unlock(&sp->mutex);
3716		subsys_put(sp);
3717	}
3718done:
3719	put_device(dev);
3720	return error;
3721 SysEntryError:
3722	if (MAJOR(dev->devt))
3723		device_remove_file(dev, &dev_attr_dev);
3724 DevAttrError:
3725	device_pm_remove(dev);
3726	dpm_sysfs_remove(dev);
3727 DPMError:
3728	device_set_driver(dev, NULL);
3729	bus_remove_device(dev);
3730 BusError:
3731	device_remove_attrs(dev);
3732 AttrsError:
3733	device_remove_class_symlinks(dev);
3734 SymlinkError:
3735	device_remove_file(dev, &dev_attr_uevent);
3736 attrError:
3737	device_platform_notify_remove(dev);
3738	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3739	glue_dir = get_glue_dir(dev);
3740	kobject_del(&dev->kobj);
3741 Error:
3742	cleanup_glue_dir(dev, glue_dir);
3743parent_error:
3744	put_device(parent);
3745name_error:
3746	kfree(dev->p);
3747	dev->p = NULL;
3748	goto done;
3749}
3750EXPORT_SYMBOL_GPL(device_add);
3751
3752/**
3753 * device_register - register a device with the system.
3754 * @dev: pointer to the device structure
3755 *
3756 * This happens in two clean steps - initialize the device
3757 * and add it to the system. The two steps can be called
3758 * separately, but this is the easiest and most common.
3759 * I.e. you should only call the two helpers separately if
3760 * have a clearly defined need to use and refcount the device
3761 * before it is added to the hierarchy.
3762 *
3763 * For more information, see the kerneldoc for device_initialize()
3764 * and device_add().
3765 *
3766 * NOTE: _Never_ directly free @dev after calling this function, even
3767 * if it returned an error! Always use put_device() to give up the
3768 * reference initialized in this function instead.
3769 */
3770int device_register(struct device *dev)
3771{
3772	device_initialize(dev);
3773	return device_add(dev);
3774}
3775EXPORT_SYMBOL_GPL(device_register);
3776
3777/**
3778 * get_device - increment reference count for device.
3779 * @dev: device.
3780 *
3781 * This simply forwards the call to kobject_get(), though
3782 * we do take care to provide for the case that we get a NULL
3783 * pointer passed in.
3784 */
3785struct device *get_device(struct device *dev)
3786{
3787	return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
3788}
3789EXPORT_SYMBOL_GPL(get_device);
3790
3791/**
3792 * put_device - decrement reference count.
3793 * @dev: device in question.
3794 */
3795void put_device(struct device *dev)
3796{
3797	/* might_sleep(); */
3798	if (dev)
3799		kobject_put(&dev->kobj);
3800}
3801EXPORT_SYMBOL_GPL(put_device);
3802
3803bool kill_device(struct device *dev)
3804{
3805	/*
3806	 * Require the device lock and set the "dead" flag to guarantee that
3807	 * the update behavior is consistent with the other bitfields near
3808	 * it and that we cannot have an asynchronous probe routine trying
3809	 * to run while we are tearing out the bus/class/sysfs from
3810	 * underneath the device.
3811	 */
3812	device_lock_assert(dev);
3813
3814	if (dev->p->dead)
3815		return false;
3816	dev->p->dead = true;
3817	return true;
3818}
3819EXPORT_SYMBOL_GPL(kill_device);
3820
3821/**
3822 * device_del - delete device from system.
3823 * @dev: device.
3824 *
3825 * This is the first part of the device unregistration
3826 * sequence. This removes the device from the lists we control
3827 * from here, has it removed from the other driver model
3828 * subsystems it was added to in device_add(), and removes it
3829 * from the kobject hierarchy.
3830 *
3831 * NOTE: this should be called manually _iff_ device_add() was
3832 * also called manually.
3833 */
3834void device_del(struct device *dev)
3835{
3836	struct subsys_private *sp;
3837	struct device *parent = dev->parent;
3838	struct kobject *glue_dir = NULL;
3839	struct class_interface *class_intf;
3840	unsigned int noio_flag;
3841
3842	device_lock(dev);
3843	kill_device(dev);
3844	device_unlock(dev);
3845
3846	if (dev->fwnode && dev->fwnode->dev == dev)
3847		dev->fwnode->dev = NULL;
3848
3849	/* Notify clients of device removal.  This call must come
3850	 * before dpm_sysfs_remove().
3851	 */
3852	noio_flag = memalloc_noio_save();
3853	bus_notify(dev, BUS_NOTIFY_DEL_DEVICE);
3854
3855	dpm_sysfs_remove(dev);
3856	if (parent)
3857		klist_del(&dev->p->knode_parent);
3858	if (MAJOR(dev->devt)) {
3859		devtmpfs_delete_node(dev);
3860		device_remove_sys_dev_entry(dev);
3861		device_remove_file(dev, &dev_attr_dev);
3862	}
3863
3864	sp = class_to_subsys(dev->class);
3865	if (sp) {
3866		device_remove_class_symlinks(dev);
3867
3868		mutex_lock(&sp->mutex);
3869		/* notify any interfaces that the device is now gone */
3870		list_for_each_entry(class_intf, &sp->interfaces, node)
3871			if (class_intf->remove_dev)
3872				class_intf->remove_dev(dev);
3873		/* remove the device from the class list */
3874		klist_del(&dev->p->knode_class);
3875		mutex_unlock(&sp->mutex);
3876		subsys_put(sp);
3877	}
3878	device_remove_file(dev, &dev_attr_uevent);
3879	device_remove_attrs(dev);
3880	bus_remove_device(dev);
3881	device_pm_remove(dev);
3882	driver_deferred_probe_del(dev);
3883	device_platform_notify_remove(dev);
3884	device_links_purge(dev);
3885
3886	/*
3887	 * If a device does not have a driver attached, we need to clean
3888	 * up any managed resources. We do this in device_release(), but
3889	 * it's never called (and we leak the device) if a managed
3890	 * resource holds a reference to the device. So release all
3891	 * managed resources here, like we do in driver_detach(). We
3892	 * still need to do so again in device_release() in case someone
3893	 * adds a new resource after this point, though.
3894	 */
3895	devres_release_all(dev);
3896
3897	bus_notify(dev, BUS_NOTIFY_REMOVED_DEVICE);
3898	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3899	glue_dir = get_glue_dir(dev);
3900	kobject_del(&dev->kobj);
3901	cleanup_glue_dir(dev, glue_dir);
3902	memalloc_noio_restore(noio_flag);
3903	put_device(parent);
3904}
3905EXPORT_SYMBOL_GPL(device_del);
3906
3907/**
3908 * device_unregister - unregister device from system.
3909 * @dev: device going away.
3910 *
3911 * We do this in two parts, like we do device_register(). First,
3912 * we remove it from all the subsystems with device_del(), then
3913 * we decrement the reference count via put_device(). If that
3914 * is the final reference count, the device will be cleaned up
3915 * via device_release() above. Otherwise, the structure will
3916 * stick around until the final reference to the device is dropped.
3917 */
3918void device_unregister(struct device *dev)
3919{
3920	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3921	device_del(dev);
3922	put_device(dev);
3923}
3924EXPORT_SYMBOL_GPL(device_unregister);
3925
3926static struct device *prev_device(struct klist_iter *i)
3927{
3928	struct klist_node *n = klist_prev(i);
3929	struct device *dev = NULL;
3930	struct device_private *p;
3931
3932	if (n) {
3933		p = to_device_private_parent(n);
3934		dev = p->device;
3935	}
3936	return dev;
3937}
3938
3939static struct device *next_device(struct klist_iter *i)
3940{
3941	struct klist_node *n = klist_next(i);
3942	struct device *dev = NULL;
3943	struct device_private *p;
3944
3945	if (n) {
3946		p = to_device_private_parent(n);
3947		dev = p->device;
3948	}
3949	return dev;
3950}
3951
3952/**
3953 * device_get_devnode - path of device node file
3954 * @dev: device
3955 * @mode: returned file access mode
3956 * @uid: returned file owner
3957 * @gid: returned file group
3958 * @tmp: possibly allocated string
3959 *
3960 * Return the relative path of a possible device node.
3961 * Non-default names may need to allocate a memory to compose
3962 * a name. This memory is returned in tmp and needs to be
3963 * freed by the caller.
3964 */
3965const char *device_get_devnode(const struct device *dev,
3966			       umode_t *mode, kuid_t *uid, kgid_t *gid,
3967			       const char **tmp)
3968{
3969	char *s;
3970
3971	*tmp = NULL;
3972
3973	/* the device type may provide a specific name */
3974	if (dev->type && dev->type->devnode)
3975		*tmp = dev->type->devnode(dev, mode, uid, gid);
3976	if (*tmp)
3977		return *tmp;
3978
3979	/* the class may provide a specific name */
3980	if (dev->class && dev->class->devnode)
3981		*tmp = dev->class->devnode(dev, mode);
3982	if (*tmp)
3983		return *tmp;
3984
3985	/* return name without allocation, tmp == NULL */
3986	if (strchr(dev_name(dev), '!') == NULL)
3987		return dev_name(dev);
3988
3989	/* replace '!' in the name with '/' */
3990	s = kstrdup_and_replace(dev_name(dev), '!', '/', GFP_KERNEL);
3991	if (!s)
3992		return NULL;
3993	return *tmp = s;
3994}
3995
3996/**
3997 * device_for_each_child - device child iterator.
3998 * @parent: parent struct device.
3999 * @data: data for the callback.
4000 * @fn: function to be called for each device.
4001 *
4002 * Iterate over @parent's child devices, and call @fn for each,
4003 * passing it @data.
4004 *
4005 * We check the return of @fn each time. If it returns anything
4006 * other than 0, we break out and return that value.
4007 */
4008int device_for_each_child(struct device *parent, void *data,
4009			  device_iter_t fn)
4010{
4011	struct klist_iter i;
4012	struct device *child;
4013	int error = 0;
4014
4015	if (!parent || !parent->p)
4016		return 0;
4017
4018	klist_iter_init(&parent->p->klist_children, &i);
4019	while (!error && (child = next_device(&i)))
4020		error = fn(child, data);
4021	klist_iter_exit(&i);
4022	return error;
4023}
4024EXPORT_SYMBOL_GPL(device_for_each_child);
4025
4026/**
4027 * device_for_each_child_reverse - device child iterator in reversed order.
4028 * @parent: parent struct device.
4029 * @data: data for the callback.
4030 * @fn: function to be called for each device.
4031 *
4032 * Iterate over @parent's child devices, and call @fn for each,
4033 * passing it @data.
4034 *
4035 * We check the return of @fn each time. If it returns anything
4036 * other than 0, we break out and return that value.
4037 */
4038int device_for_each_child_reverse(struct device *parent, void *data,
4039				  device_iter_t fn)
4040{
4041	struct klist_iter i;
4042	struct device *child;
4043	int error = 0;
4044
4045	if (!parent || !parent->p)
4046		return 0;
4047
4048	klist_iter_init(&parent->p->klist_children, &i);
4049	while ((child = prev_device(&i)) && !error)
4050		error = fn(child, data);
4051	klist_iter_exit(&i);
4052	return error;
4053}
4054EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
4055
4056/**
4057 * device_for_each_child_reverse_from - device child iterator in reversed order.
4058 * @parent: parent struct device.
4059 * @from: optional starting point in child list
4060 * @data: data for the callback.
4061 * @fn: function to be called for each device.
4062 *
4063 * Iterate over @parent's child devices, starting at @from, and call @fn
4064 * for each, passing it @data. This helper is identical to
4065 * device_for_each_child_reverse() when @from is NULL.
4066 *
4067 * @fn is checked each iteration. If it returns anything other than 0,
4068 * iteration stop and that value is returned to the caller of
4069 * device_for_each_child_reverse_from();
4070 */
4071int device_for_each_child_reverse_from(struct device *parent,
4072				       struct device *from, void *data,
4073				       device_iter_t fn)
4074{
4075	struct klist_iter i;
4076	struct device *child;
4077	int error = 0;
4078
4079	if (!parent || !parent->p)
4080		return 0;
4081
4082	klist_iter_init_node(&parent->p->klist_children, &i,
4083			     (from ? &from->p->knode_parent : NULL));
4084	while ((child = prev_device(&i)) && !error)
4085		error = fn(child, data);
4086	klist_iter_exit(&i);
4087	return error;
4088}
4089EXPORT_SYMBOL_GPL(device_for_each_child_reverse_from);
4090
4091/**
4092 * device_find_child - device iterator for locating a particular device.
4093 * @parent: parent struct device
4094 * @data: Data to pass to match function
4095 * @match: Callback function to check device
4096 *
4097 * This is similar to the device_for_each_child() function above, but it
4098 * returns a reference to a device that is 'found' for later use, as
4099 * determined by the @match callback.
4100 *
4101 * The callback should return 0 if the device doesn't match and non-zero
4102 * if it does.  If the callback returns non-zero and a reference to the
4103 * current device can be obtained, this function will return to the caller
4104 * and not iterate over any more devices.
4105 *
4106 * NOTE: you will need to drop the reference with put_device() after use.
4107 */
4108struct device *device_find_child(struct device *parent, const void *data,
4109				 device_match_t match)
4110{
4111	struct klist_iter i;
4112	struct device *child;
4113
4114	if (!parent || !parent->p)
4115		return NULL;
4116
4117	klist_iter_init(&parent->p->klist_children, &i);
4118	while ((child = next_device(&i))) {
4119		if (match(child, data)) {
4120			get_device(child);
4121			break;
4122		}
4123	}
4124	klist_iter_exit(&i);
4125	return child;
4126}
4127EXPORT_SYMBOL_GPL(device_find_child);
4128
4129int __init devices_init(void)
4130{
4131	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
4132	if (!devices_kset)
4133		return -ENOMEM;
4134	dev_kobj = kobject_create_and_add("dev", NULL);
4135	if (!dev_kobj)
4136		goto dev_kobj_err;
4137	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
4138	if (!sysfs_dev_block_kobj)
4139		goto block_kobj_err;
4140	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
4141	if (!sysfs_dev_char_kobj)
4142		goto char_kobj_err;
4143	device_link_wq = alloc_workqueue("device_link_wq", WQ_PERCPU, 0);
4144	if (!device_link_wq)
4145		goto wq_err;
4146
4147	return 0;
4148
4149 wq_err:
4150	kobject_put(sysfs_dev_char_kobj);
4151 char_kobj_err:
4152	kobject_put(sysfs_dev_block_kobj);
4153 block_kobj_err:
4154	kobject_put(dev_kobj);
4155 dev_kobj_err:
4156	kset_unregister(devices_kset);
4157	return -ENOMEM;
4158}
4159
4160static int device_check_offline(struct device *dev, void *not_used)
4161{
4162	int ret;
4163
4164	ret = device_for_each_child(dev, NULL, device_check_offline);
4165	if (ret)
4166		return ret;
4167
4168	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
4169}
4170
4171/**
4172 * device_offline - Prepare the device for hot-removal.
4173 * @dev: Device to be put offline.
4174 *
4175 * Execute the device bus type's .offline() callback, if present, to prepare
4176 * the device for a subsequent hot-removal.  If that succeeds, the device must
4177 * not be used until either it is removed or its bus type's .online() callback
4178 * is executed.
4179 *
4180 * Call under device_hotplug_lock.
4181 */
4182int device_offline(struct device *dev)
4183{
4184	int ret;
4185
4186	if (dev->offline_disabled)
4187		return -EPERM;
4188
4189	ret = device_for_each_child(dev, NULL, device_check_offline);
4190	if (ret)
4191		return ret;
4192
4193	device_lock(dev);
4194	if (device_supports_offline(dev)) {
4195		if (dev->offline) {
4196			ret = 1;
4197		} else {
4198			ret = dev->bus->offline(dev);
4199			if (!ret) {
4200				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
4201				dev->offline = true;
4202			}
4203		}
4204	}
4205	device_unlock(dev);
4206
4207	return ret;
4208}
4209
4210/**
4211 * device_online - Put the device back online after successful device_offline().
4212 * @dev: Device to be put back online.
4213 *
4214 * If device_offline() has been successfully executed for @dev, but the device
4215 * has not been removed subsequently, execute its bus type's .online() callback
4216 * to indicate that the device can be used again.
4217 *
4218 * Call under device_hotplug_lock.
4219 */
4220int device_online(struct device *dev)
4221{
4222	int ret = 0;
4223
4224	device_lock(dev);
4225	if (device_supports_offline(dev)) {
4226		if (dev->offline) {
4227			ret = dev->bus->online(dev);
4228			if (!ret) {
4229				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
4230				dev->offline = false;
4231			}
4232		} else {
4233			ret = 1;
4234		}
4235	}
4236	device_unlock(dev);
4237
4238	return ret;
4239}
4240
4241struct root_device {
4242	struct device dev;
4243	struct module *owner;
4244};
4245
4246static inline struct root_device *to_root_device(struct device *d)
4247{
4248	return container_of(d, struct root_device, dev);
4249}
4250
4251static void root_device_release(struct device *dev)
4252{
4253	kfree(to_root_device(dev));
4254}
4255
4256/**
4257 * __root_device_register - allocate and register a root device
4258 * @name: root device name
4259 * @owner: owner module of the root device, usually THIS_MODULE
4260 *
4261 * This function allocates a root device and registers it
4262 * using device_register(). In order to free the returned
4263 * device, use root_device_unregister().
4264 *
4265 * Root devices are dummy devices which allow other devices
4266 * to be grouped under /sys/devices. Use this function to
4267 * allocate a root device and then use it as the parent of
4268 * any device which should appear under /sys/devices/{name}
4269 *
4270 * The /sys/devices/{name} directory will also contain a
4271 * 'module' symlink which points to the @owner directory
4272 * in sysfs.
4273 *
4274 * Returns &struct device pointer on success, or ERR_PTR() on error.
4275 *
4276 * Note: You probably want to use root_device_register().
4277 */
4278struct device *__root_device_register(const char *name, struct module *owner)
4279{
4280	struct root_device *root;
4281	int err = -ENOMEM;
4282
4283	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
4284	if (!root)
4285		return ERR_PTR(err);
4286
4287	err = dev_set_name(&root->dev, "%s", name);
4288	if (err) {
4289		kfree(root);
4290		return ERR_PTR(err);
4291	}
4292
4293	root->dev.release = root_device_release;
4294
4295	err = device_register(&root->dev);
4296	if (err) {
4297		put_device(&root->dev);
4298		return ERR_PTR(err);
4299	}
4300
4301#ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
4302	if (owner) {
4303		struct module_kobject *mk = &owner->mkobj;
4304
4305		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
4306		if (err) {
4307			device_unregister(&root->dev);
4308			return ERR_PTR(err);
4309		}
4310		root->owner = owner;
4311	}
4312#endif
4313
4314	return &root->dev;
4315}
4316EXPORT_SYMBOL_GPL(__root_device_register);
4317
4318/**
4319 * root_device_unregister - unregister and free a root device
4320 * @dev: device going away
4321 *
4322 * This function unregisters and cleans up a device that was created by
4323 * root_device_register().
4324 */
4325void root_device_unregister(struct device *dev)
4326{
4327	struct root_device *root = to_root_device(dev);
4328
4329	if (root->owner)
4330		sysfs_remove_link(&root->dev.kobj, "module");
4331
4332	device_unregister(dev);
4333}
4334EXPORT_SYMBOL_GPL(root_device_unregister);
4335
4336
4337static void device_create_release(struct device *dev)
4338{
4339	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
4340	kfree(dev);
4341}
4342
4343static __printf(6, 0) struct device *
4344device_create_groups_vargs(const struct class *class, struct device *parent,
4345			   dev_t devt, void *drvdata,
4346			   const struct attribute_group **groups,
4347			   const char *fmt, va_list args)
4348{
4349	struct device *dev = NULL;
4350	int retval = -ENODEV;
4351
4352	if (IS_ERR_OR_NULL(class))
4353		goto error;
4354
4355	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
4356	if (!dev) {
4357		retval = -ENOMEM;
4358		goto error;
4359	}
4360
4361	device_initialize(dev);
4362	dev->devt = devt;
4363	dev->class = class;
4364	dev->parent = parent;
4365	dev->groups = groups;
4366	dev->release = device_create_release;
4367	dev_set_drvdata(dev, drvdata);
4368
4369	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
4370	if (retval)
4371		goto error;
4372
4373	retval = device_add(dev);
4374	if (retval)
4375		goto error;
4376
4377	return dev;
4378
4379error:
4380	put_device(dev);
4381	return ERR_PTR(retval);
4382}
4383
4384/**
4385 * device_create - creates a device and registers it with sysfs
4386 * @class: pointer to the struct class that this device should be registered to
4387 * @parent: pointer to the parent struct device of this new device, if any
4388 * @devt: the dev_t for the char device to be added
4389 * @drvdata: the data to be added to the device for callbacks
4390 * @fmt: string for the device's name
4391 *
4392 * This function can be used by char device classes.  A struct device
4393 * will be created in sysfs, registered to the specified class.
4394 *
4395 * A "dev" file will be created, showing the dev_t for the device, if
4396 * the dev_t is not 0,0.
4397 * If a pointer to a parent struct device is passed in, the newly created
4398 * struct device will be a child of that device in sysfs.
4399 * The pointer to the struct device will be returned from the call.
4400 * Any further sysfs files that might be required can be created using this
4401 * pointer.
4402 *
4403 * Returns &struct device pointer on success, or ERR_PTR() on error.
4404 */
4405struct device *device_create(const struct class *class, struct device *parent,
4406			     dev_t devt, void *drvdata, const char *fmt, ...)
4407{
4408	va_list vargs;
4409	struct device *dev;
4410
4411	va_start(vargs, fmt);
4412	dev = device_create_groups_vargs(class, parent, devt, drvdata, NULL,
4413					  fmt, vargs);
4414	va_end(vargs);
4415	return dev;
4416}
4417EXPORT_SYMBOL_GPL(device_create);
4418
4419/**
4420 * device_create_with_groups - creates a device and registers it with sysfs
4421 * @class: pointer to the struct class that this device should be registered to
4422 * @parent: pointer to the parent struct device of this new device, if any
4423 * @devt: the dev_t for the char device to be added
4424 * @drvdata: the data to be added to the device for callbacks
4425 * @groups: NULL-terminated list of attribute groups to be created
4426 * @fmt: string for the device's name
4427 *
4428 * This function can be used by char device classes.  A struct device
4429 * will be created in sysfs, registered to the specified class.
4430 * Additional attributes specified in the groups parameter will also
4431 * be created automatically.
4432 *
4433 * A "dev" file will be created, showing the dev_t for the device, if
4434 * the dev_t is not 0,0.
4435 * If a pointer to a parent struct device is passed in, the newly created
4436 * struct device will be a child of that device in sysfs.
4437 * The pointer to the struct device will be returned from the call.
4438 * Any further sysfs files that might be required can be created using this
4439 * pointer.
4440 *
4441 * Returns &struct device pointer on success, or ERR_PTR() on error.
4442 */
4443struct device *device_create_with_groups(const struct class *class,
4444					 struct device *parent, dev_t devt,
4445					 void *drvdata,
4446					 const struct attribute_group **groups,
4447					 const char *fmt, ...)
4448{
4449	va_list vargs;
4450	struct device *dev;
4451
4452	va_start(vargs, fmt);
4453	dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
4454					 fmt, vargs);
4455	va_end(vargs);
4456	return dev;
4457}
4458EXPORT_SYMBOL_GPL(device_create_with_groups);
4459
4460/**
4461 * device_destroy - removes a device that was created with device_create()
4462 * @class: pointer to the struct class that this device was registered with
4463 * @devt: the dev_t of the device that was previously registered
4464 *
4465 * This call unregisters and cleans up a device that was created with a
4466 * call to device_create().
4467 */
4468void device_destroy(const struct class *class, dev_t devt)
4469{
4470	struct device *dev;
4471
4472	dev = class_find_device_by_devt(class, devt);
4473	if (dev) {
4474		put_device(dev);
4475		device_unregister(dev);
4476	}
4477}
4478EXPORT_SYMBOL_GPL(device_destroy);
4479
4480/**
4481 * device_rename - renames a device
4482 * @dev: the pointer to the struct device to be renamed
4483 * @new_name: the new name of the device
4484 *
4485 * It is the responsibility of the caller to provide mutual
4486 * exclusion between two different calls of device_rename
4487 * on the same device to ensure that new_name is valid and
4488 * won't conflict with other devices.
4489 *
4490 * Note: given that some subsystems (networking and infiniband) use this
4491 * function, with no immediate plans for this to change, we cannot assume or
4492 * require that this function not be called at all.
4493 *
4494 * However, if you're writing new code, do not call this function. The following
4495 * text from Kay Sievers offers some insight:
4496 *
4497 * Renaming devices is racy at many levels, symlinks and other stuff are not
4498 * replaced atomically, and you get a "move" uevent, but it's not easy to
4499 * connect the event to the old and new device. Device nodes are not renamed at
4500 * all, there isn't even support for that in the kernel now.
4501 *
4502 * In the meantime, during renaming, your target name might be taken by another
4503 * driver, creating conflicts. Or the old name is taken directly after you
4504 * renamed it -- then you get events for the same DEVPATH, before you even see
4505 * the "move" event. It's just a mess, and nothing new should ever rely on
4506 * kernel device renaming. Besides that, it's not even implemented now for
4507 * other things than (driver-core wise very simple) network devices.
4508 *
4509 * Make up a "real" name in the driver before you register anything, or add
4510 * some other attributes for userspace to find the device, or use udev to add
4511 * symlinks -- but never rename kernel devices later, it's a complete mess. We
4512 * don't even want to get into that and try to implement the missing pieces in
4513 * the core. We really have other pieces to fix in the driver core mess. :)
4514 */
4515int device_rename(struct device *dev, const char *new_name)
4516{
4517	struct subsys_private *sp = NULL;
4518	struct kobject *kobj = &dev->kobj;
4519	char *old_device_name = NULL;
4520	int error;
4521	bool is_link_renamed = false;
4522
4523	dev = get_device(dev);
4524	if (!dev)
4525		return -EINVAL;
4526
4527	dev_dbg(dev, "renaming to %s\n", new_name);
4528
4529	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
4530	if (!old_device_name) {
4531		error = -ENOMEM;
4532		goto out;
4533	}
4534
4535	if (dev->class) {
4536		sp = class_to_subsys(dev->class);
4537
4538		if (!sp) {
4539			error = -EINVAL;
4540			goto out;
4541		}
4542
4543		error = sysfs_rename_link_ns(&sp->subsys.kobj, kobj, old_device_name,
4544					     new_name, kobject_namespace(kobj));
4545		if (error)
4546			goto out;
4547
4548		is_link_renamed = true;
4549	}
4550
4551	error = kobject_rename(kobj, new_name);
4552out:
4553	if (error && is_link_renamed)
4554		sysfs_rename_link_ns(&sp->subsys.kobj, kobj, new_name,
4555				     old_device_name, kobject_namespace(kobj));
4556	subsys_put(sp);
4557
4558	put_device(dev);
4559
4560	kfree(old_device_name);
4561
4562	return error;
4563}
4564EXPORT_SYMBOL_GPL(device_rename);
4565
4566static int device_move_class_links(struct device *dev,
4567				   struct device *old_parent,
4568				   struct device *new_parent)
4569{
4570	int error = 0;
4571
4572	if (old_parent)
4573		sysfs_remove_link(&dev->kobj, "device");
4574	if (new_parent)
4575		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
4576					  "device");
4577	return error;
4578}
4579
4580/**
4581 * device_move - moves a device to a new parent
4582 * @dev: the pointer to the struct device to be moved
4583 * @new_parent: the new parent of the device (can be NULL)
4584 * @dpm_order: how to reorder the dpm_list
4585 */
4586int device_move(struct device *dev, struct device *new_parent,
4587		enum dpm_order dpm_order)
4588{
4589	int error;
4590	struct device *old_parent;
4591	struct kobject *new_parent_kobj;
4592
4593	dev = get_device(dev);
4594	if (!dev)
4595		return -EINVAL;
4596
4597	device_pm_lock();
4598	new_parent = get_device(new_parent);
4599	new_parent_kobj = get_device_parent(dev, new_parent);
4600	if (IS_ERR(new_parent_kobj)) {
4601		error = PTR_ERR(new_parent_kobj);
4602		put_device(new_parent);
4603		goto out;
4604	}
4605
4606	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
4607		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
4608	error = kobject_move(&dev->kobj, new_parent_kobj);
4609	if (error) {
4610		cleanup_glue_dir(dev, new_parent_kobj);
4611		put_device(new_parent);
4612		goto out;
4613	}
4614	old_parent = dev->parent;
4615	dev->parent = new_parent;
4616	if (old_parent)
4617		klist_remove(&dev->p->knode_parent);
4618	if (new_parent) {
4619		klist_add_tail(&dev->p->knode_parent,
4620			       &new_parent->p->klist_children);
4621		set_dev_node(dev, dev_to_node(new_parent));
4622	}
4623
4624	if (dev->class) {
4625		error = device_move_class_links(dev, old_parent, new_parent);
4626		if (error) {
4627			/* We ignore errors on cleanup since we're hosed anyway... */
4628			device_move_class_links(dev, new_parent, old_parent);
4629			if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
4630				if (new_parent)
4631					klist_remove(&dev->p->knode_parent);
4632				dev->parent = old_parent;
4633				if (old_parent) {
4634					klist_add_tail(&dev->p->knode_parent,
4635						       &old_parent->p->klist_children);
4636					set_dev_node(dev, dev_to_node(old_parent));
4637				}
4638			}
4639			cleanup_glue_dir(dev, new_parent_kobj);
4640			put_device(new_parent);
4641			goto out;
4642		}
4643	}
4644	switch (dpm_order) {
4645	case DPM_ORDER_NONE:
4646		break;
4647	case DPM_ORDER_DEV_AFTER_PARENT:
4648		device_pm_move_after(dev, new_parent);
4649		devices_kset_move_after(dev, new_parent);
4650		break;
4651	case DPM_ORDER_PARENT_BEFORE_DEV:
4652		device_pm_move_before(new_parent, dev);
4653		devices_kset_move_before(new_parent, dev);
4654		break;
4655	case DPM_ORDER_DEV_LAST:
4656		device_pm_move_last(dev);
4657		devices_kset_move_last(dev);
4658		break;
4659	}
4660
4661	put_device(old_parent);
4662out:
4663	device_pm_unlock();
4664	put_device(dev);
4665	return error;
4666}
4667EXPORT_SYMBOL_GPL(device_move);
4668
4669static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
4670				     kgid_t kgid)
4671{
4672	struct kobject *kobj = &dev->kobj;
4673	const struct class *class = dev->class;
4674	const struct device_type *type = dev->type;
4675	int error;
4676
4677	if (class) {
4678		/*
4679		 * Change the device groups of the device class for @dev to
4680		 * @kuid/@kgid.
4681		 */
4682		error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
4683						  kgid);
4684		if (error)
4685			return error;
4686	}
4687
4688	if (type) {
4689		/*
4690		 * Change the device groups of the device type for @dev to
4691		 * @kuid/@kgid.
4692		 */
4693		error = sysfs_groups_change_owner(kobj, type->groups, kuid,
4694						  kgid);
4695		if (error)
4696			return error;
4697	}
4698
4699	/* Change the device groups of @dev to @kuid/@kgid. */
4700	error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
4701	if (error)
4702		return error;
4703
4704	if (device_supports_offline(dev) && !dev->offline_disabled) {
4705		/* Change online device attributes of @dev to @kuid/@kgid. */
4706		error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
4707						kuid, kgid);
4708		if (error)
4709			return error;
4710	}
4711
4712	return 0;
4713}
4714
4715/**
4716 * device_change_owner - change the owner of an existing device.
4717 * @dev: device.
4718 * @kuid: new owner's kuid
4719 * @kgid: new owner's kgid
4720 *
4721 * This changes the owner of @dev and its corresponding sysfs entries to
4722 * @kuid/@kgid. This function closely mirrors how @dev was added via driver
4723 * core.
4724 *
4725 * Returns 0 on success or error code on failure.
4726 */
4727int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
4728{
4729	int error;
4730	struct kobject *kobj = &dev->kobj;
4731	struct subsys_private *sp;
4732
4733	dev = get_device(dev);
4734	if (!dev)
4735		return -EINVAL;
4736
4737	/*
4738	 * Change the kobject and the default attributes and groups of the
4739	 * ktype associated with it to @kuid/@kgid.
4740	 */
4741	error = sysfs_change_owner(kobj, kuid, kgid);
4742	if (error)
4743		goto out;
4744
4745	/*
4746	 * Change the uevent file for @dev to the new owner. The uevent file
4747	 * was created in a separate step when @dev got added and we mirror
4748	 * that step here.
4749	 */
4750	error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
4751					kgid);
4752	if (error)
4753		goto out;
4754
4755	/*
4756	 * Change the device groups, the device groups associated with the
4757	 * device class, and the groups associated with the device type of @dev
4758	 * to @kuid/@kgid.
4759	 */
4760	error = device_attrs_change_owner(dev, kuid, kgid);
4761	if (error)
4762		goto out;
4763
4764	error = dpm_sysfs_change_owner(dev, kuid, kgid);
4765	if (error)
4766		goto out;
4767
4768	/*
4769	 * Change the owner of the symlink located in the class directory of
4770	 * the device class associated with @dev which points to the actual
4771	 * directory entry for @dev to @kuid/@kgid. This ensures that the
4772	 * symlink shows the same permissions as its target.
4773	 */
4774	sp = class_to_subsys(dev->class);
4775	if (!sp) {
4776		error = -EINVAL;
4777		goto out;
4778	}
4779	error = sysfs_link_change_owner(&sp->subsys.kobj, &dev->kobj, dev_name(dev), kuid, kgid);
4780	subsys_put(sp);
4781
4782out:
4783	put_device(dev);
4784	return error;
4785}
4786EXPORT_SYMBOL_GPL(device_change_owner);
4787
4788/**
4789 * device_shutdown - call ->shutdown() on each device to shutdown.
4790 */
4791void device_shutdown(void)
4792{
4793	struct device *dev, *parent;
4794
4795	wait_for_device_probe();
4796	device_block_probing();
4797
4798	cpufreq_suspend();
4799
4800	spin_lock(&devices_kset->list_lock);
4801	/*
4802	 * Walk the devices list backward, shutting down each in turn.
4803	 * Beware that device unplug events may also start pulling
4804	 * devices offline, even as the system is shutting down.
4805	 */
4806	while (!list_empty(&devices_kset->list)) {
4807		dev = list_entry(devices_kset->list.prev, struct device,
4808				kobj.entry);
4809
4810		/*
4811		 * hold reference count of device's parent to
4812		 * prevent it from being freed because parent's
4813		 * lock is to be held
4814		 */
4815		parent = get_device(dev->parent);
4816		get_device(dev);
4817		/*
4818		 * Make sure the device is off the kset list, in the
4819		 * event that dev->*->shutdown() doesn't remove it.
4820		 */
4821		list_del_init(&dev->kobj.entry);
4822		spin_unlock(&devices_kset->list_lock);
4823
4824		/* hold lock to avoid race with probe/release */
4825		if (parent)
4826			device_lock(parent);
4827		device_lock(dev);
4828
4829		/* Don't allow any more runtime suspends */
4830		pm_runtime_get_noresume(dev);
4831		pm_runtime_barrier(dev);
4832
4833		if (dev->class && dev->class->shutdown_pre) {
4834			if (initcall_debug)
4835				dev_info(dev, "shutdown_pre\n");
4836			dev->class->shutdown_pre(dev);
4837		}
4838		if (dev->bus && dev->bus->shutdown) {
4839			if (initcall_debug)
4840				dev_info(dev, "shutdown\n");
4841			dev->bus->shutdown(dev);
4842		} else if (dev->driver && dev->driver->shutdown) {
4843			if (initcall_debug)
4844				dev_info(dev, "shutdown\n");
4845			dev->driver->shutdown(dev);
4846		}
4847
4848		device_unlock(dev);
4849		if (parent)
4850			device_unlock(parent);
4851
4852		put_device(dev);
4853		put_device(parent);
4854
4855		spin_lock(&devices_kset->list_lock);
4856	}
4857	spin_unlock(&devices_kset->list_lock);
4858}
4859
4860/*
4861 * Device logging functions
4862 */
4863
4864#ifdef CONFIG_PRINTK
4865static void
4866set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
4867{
4868	const char *subsys;
4869
4870	memset(dev_info, 0, sizeof(*dev_info));
4871
4872	if (dev->class)
4873		subsys = dev->class->name;
4874	else if (dev->bus)
4875		subsys = dev->bus->name;
4876	else
4877		return;
4878
4879	strscpy(dev_info->subsystem, subsys);
4880
4881	/*
4882	 * Add device identifier DEVICE=:
4883	 *   b12:8         block dev_t
4884	 *   c127:3        char dev_t
4885	 *   n8            netdev ifindex
4886	 *   +sound:card0  subsystem:devname
4887	 */
4888	if (MAJOR(dev->devt)) {
4889		char c;
4890
4891		if (strcmp(subsys, "block") == 0)
4892			c = 'b';
4893		else
4894			c = 'c';
4895
4896		snprintf(dev_info->device, sizeof(dev_info->device),
4897			 "%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
4898	} else if (strcmp(subsys, "net") == 0) {
4899		struct net_device *net = to_net_dev(dev);
4900
4901		snprintf(dev_info->device, sizeof(dev_info->device),
4902			 "n%u", net->ifindex);
4903	} else {
4904		snprintf(dev_info->device, sizeof(dev_info->device),
4905			 "+%s:%s", subsys, dev_name(dev));
4906	}
4907}
4908
4909int dev_vprintk_emit(int level, const struct device *dev,
4910		     const char *fmt, va_list args)
4911{
4912	struct dev_printk_info dev_info;
4913
4914	set_dev_info(dev, &dev_info);
4915
4916	return vprintk_emit(0, level, &dev_info, fmt, args);
4917}
4918EXPORT_SYMBOL(dev_vprintk_emit);
4919
4920int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
4921{
4922	va_list args;
4923	int r;
4924
4925	va_start(args, fmt);
4926
4927	r = dev_vprintk_emit(level, dev, fmt, args);
4928
4929	va_end(args);
4930
4931	return r;
4932}
4933EXPORT_SYMBOL(dev_printk_emit);
4934
4935static void __dev_printk(const char *level, const struct device *dev,
4936			struct va_format *vaf)
4937{
4938	if (dev)
4939		dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
4940				dev_driver_string(dev), dev_name(dev), vaf);
4941	else
4942		printk("%s(NULL device *): %pV", level, vaf);
4943}
4944
4945void _dev_printk(const char *level, const struct device *dev,
4946		 const char *fmt, ...)
4947{
4948	struct va_format vaf;
4949	va_list args;
4950
4951	va_start(args, fmt);
4952
4953	vaf.fmt = fmt;
4954	vaf.va = &args;
4955
4956	__dev_printk(level, dev, &vaf);
4957
4958	va_end(args);
4959}
4960EXPORT_SYMBOL(_dev_printk);
4961
4962#define define_dev_printk_level(func, kern_level)		\
4963void func(const struct device *dev, const char *fmt, ...)	\
4964{								\
4965	struct va_format vaf;					\
4966	va_list args;						\
4967								\
4968	va_start(args, fmt);					\
4969								\
4970	vaf.fmt = fmt;						\
4971	vaf.va = &args;						\
4972								\
4973	__dev_printk(kern_level, dev, &vaf);			\
4974								\
4975	va_end(args);						\
4976}								\
4977EXPORT_SYMBOL(func);
4978
4979define_dev_printk_level(_dev_emerg, KERN_EMERG);
4980define_dev_printk_level(_dev_alert, KERN_ALERT);
4981define_dev_printk_level(_dev_crit, KERN_CRIT);
4982define_dev_printk_level(_dev_err, KERN_ERR);
4983define_dev_printk_level(_dev_warn, KERN_WARNING);
4984define_dev_printk_level(_dev_notice, KERN_NOTICE);
4985define_dev_printk_level(_dev_info, KERN_INFO);
4986
4987#endif
4988
4989static void __dev_probe_failed(const struct device *dev, int err, bool fatal,
4990			       const char *fmt, va_list vargsp)
4991{
4992	struct va_format vaf;
4993	va_list vargs;
4994
4995	/*
4996	 * On x86_64 and possibly on other architectures, va_list is actually a
4997	 * size-1 array containing a structure.  As a result, function parameter
4998	 * vargsp decays from T[1] to T*, and &vargsp has type T** rather than
4999	 * T(*)[1], which is expected by its assignment to vaf.va below.
5000	 *
5001	 * One standard way to solve this mess is by creating a copy in a local
5002	 * variable of type va_list and then using a pointer to that local copy
5003	 * instead, which is the approach employed here.
5004	 */
5005	va_copy(vargs, vargsp);
5006
5007	vaf.fmt = fmt;
5008	vaf.va = &vargs;
5009
5010	switch (err) {
5011	case -EPROBE_DEFER:
5012		device_set_deferred_probe_reason(dev, &vaf);
5013		dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5014		break;
5015
5016	case -ENOMEM:
5017		/* Don't print anything on -ENOMEM, there's already enough output */
5018		break;
5019
5020	default:
5021		/* Log fatal final failures as errors, otherwise produce warnings */
5022		if (fatal)
5023			dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5024		else
5025			dev_warn(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5026		break;
5027	}
5028
5029	va_end(vargs);
5030}
5031
5032/**
5033 * dev_err_probe - probe error check and log helper
5034 * @dev: the pointer to the struct device
5035 * @err: error value to test
5036 * @fmt: printf-style format string
5037 * @...: arguments as specified in the format string
5038 *
5039 * This helper implements common pattern present in probe functions for error
5040 * checking: print debug or error message depending if the error value is
5041 * -EPROBE_DEFER and propagate error upwards.
5042 * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
5043 * checked later by reading devices_deferred debugfs attribute.
5044 * It replaces the following code sequence::
5045 *
5046 * 	if (err != -EPROBE_DEFER)
5047 * 		dev_err(dev, ...);
5048 * 	else
5049 * 		dev_dbg(dev, ...);
5050 * 	return err;
5051 *
5052 * with::
5053 *
5054 * 	return dev_err_probe(dev, err, ...);
5055 *
5056 * Using this helper in your probe function is totally fine even if @err
5057 * is known to never be -EPROBE_DEFER.
5058 * The benefit compared to a normal dev_err() is the standardized format
5059 * of the error code, which is emitted symbolically (i.e. you get "EAGAIN"
5060 * instead of "-35"), and having the error code returned allows more
5061 * compact error paths.
5062 *
5063 * Returns @err.
5064 */
5065int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
5066{
5067	va_list vargs;
5068
5069	va_start(vargs, fmt);
5070
5071	/* Use dev_err() for logging when err doesn't equal -EPROBE_DEFER */
5072	__dev_probe_failed(dev, err, true, fmt, vargs);
5073
5074	va_end(vargs);
5075
5076	return err;
5077}
5078EXPORT_SYMBOL_GPL(dev_err_probe);
5079
5080/**
5081 * dev_warn_probe - probe error check and log helper
5082 * @dev: the pointer to the struct device
5083 * @err: error value to test
5084 * @fmt: printf-style format string
5085 * @...: arguments as specified in the format string
5086 *
5087 * This helper implements common pattern present in probe functions for error
5088 * checking: print debug or warning message depending if the error value is
5089 * -EPROBE_DEFER and propagate error upwards.
5090 * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
5091 * checked later by reading devices_deferred debugfs attribute.
5092 * It replaces the following code sequence::
5093 *
5094 * 	if (err != -EPROBE_DEFER)
5095 * 		dev_warn(dev, ...);
5096 * 	else
5097 * 		dev_dbg(dev, ...);
5098 * 	return err;
5099 *
5100 * with::
5101 *
5102 * 	return dev_warn_probe(dev, err, ...);
5103 *
5104 * Using this helper in your probe function is totally fine even if @err
5105 * is known to never be -EPROBE_DEFER.
5106 * The benefit compared to a normal dev_warn() is the standardized format
5107 * of the error code, which is emitted symbolically (i.e. you get "EAGAIN"
5108 * instead of "-35"), and having the error code returned allows more
5109 * compact error paths.
5110 *
5111 * Returns @err.
5112 */
5113int dev_warn_probe(const struct device *dev, int err, const char *fmt, ...)
5114{
5115	va_list vargs;
5116
5117	va_start(vargs, fmt);
5118
5119	/* Use dev_warn() for logging when err doesn't equal -EPROBE_DEFER */
5120	__dev_probe_failed(dev, err, false, fmt, vargs);
5121
5122	va_end(vargs);
5123
5124	return err;
5125}
5126EXPORT_SYMBOL_GPL(dev_warn_probe);
5127
5128static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
5129{
5130	return fwnode && !IS_ERR(fwnode->secondary);
5131}
5132
5133/**
5134 * set_primary_fwnode - Change the primary firmware node of a given device.
5135 * @dev: Device to handle.
5136 * @fwnode: New primary firmware node of the device.
5137 *
5138 * Set the device's firmware node pointer to @fwnode, but if a secondary
5139 * firmware node of the device is present, preserve it.
5140 *
5141 * Valid fwnode cases are:
5142 *  - primary --> secondary --> -ENODEV
5143 *  - primary --> NULL
5144 *  - secondary --> -ENODEV
5145 *  - NULL
5146 */
5147void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5148{
5149	struct device *parent = dev->parent;
5150	struct fwnode_handle *fn = dev->fwnode;
5151
5152	if (fwnode) {
5153		if (fwnode_is_primary(fn))
5154			fn = fn->secondary;
5155
5156		if (fn) {
5157			WARN_ON(fwnode->secondary);
5158			fwnode->secondary = fn;
5159		}
5160		dev->fwnode = fwnode;
5161	} else {
5162		if (fwnode_is_primary(fn)) {
5163			dev->fwnode = fn->secondary;
5164
5165			/* Skip nullifying fn->secondary if the primary is shared */
5166			if (parent && fn == parent->fwnode)
5167				return;
5168
5169			/* Set fn->secondary = NULL, so fn remains the primary fwnode */
5170			fn->secondary = NULL;
5171		} else {
5172			dev->fwnode = NULL;
5173		}
5174	}
5175}
5176EXPORT_SYMBOL_GPL(set_primary_fwnode);
5177
5178/**
5179 * set_secondary_fwnode - Change the secondary firmware node of a given device.
5180 * @dev: Device to handle.
5181 * @fwnode: New secondary firmware node of the device.
5182 *
5183 * If a primary firmware node of the device is present, set its secondary
5184 * pointer to @fwnode.  Otherwise, set the device's firmware node pointer to
5185 * @fwnode.
5186 */
5187void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5188{
5189	if (fwnode)
5190		fwnode->secondary = ERR_PTR(-ENODEV);
5191
5192	if (fwnode_is_primary(dev->fwnode))
5193		dev->fwnode->secondary = fwnode;
5194	else
5195		dev->fwnode = fwnode;
5196}
5197EXPORT_SYMBOL_GPL(set_secondary_fwnode);
5198
5199/**
5200 * device_remove_of_node - Remove an of_node from a device
5201 * @dev: device whose device tree node is being removed
5202 */
5203void device_remove_of_node(struct device *dev)
5204{
5205	dev = get_device(dev);
5206	if (!dev)
5207		return;
5208
5209	if (!dev->of_node)
5210		goto end;
5211
5212	if (dev->fwnode == of_fwnode_handle(dev->of_node))
5213		dev->fwnode = NULL;
5214
5215	of_node_put(dev->of_node);
5216	dev->of_node = NULL;
5217
5218end:
5219	put_device(dev);
5220}
5221EXPORT_SYMBOL_GPL(device_remove_of_node);
5222
5223/**
5224 * device_add_of_node - Add an of_node to an existing device
5225 * @dev: device whose device tree node is being added
5226 * @of_node: of_node to add
5227 *
5228 * Return: 0 on success or error code on failure.
5229 */
5230int device_add_of_node(struct device *dev, struct device_node *of_node)
5231{
5232	int ret;
5233
5234	if (!of_node)
5235		return -EINVAL;
5236
5237	dev = get_device(dev);
5238	if (!dev)
5239		return -EINVAL;
5240
5241	if (dev->of_node) {
5242		dev_err(dev, "Cannot replace node %pOF with %pOF\n",
5243			dev->of_node, of_node);
5244		ret = -EBUSY;
5245		goto end;
5246	}
5247
5248	dev->of_node = of_node_get(of_node);
5249
5250	if (!dev->fwnode)
5251		dev->fwnode = of_fwnode_handle(of_node);
5252
5253	ret = 0;
5254end:
5255	put_device(dev);
5256	return ret;
5257}
5258EXPORT_SYMBOL_GPL(device_add_of_node);
5259
5260/**
5261 * device_set_of_node_from_dev - reuse device-tree node of another device
5262 * @dev: device whose device-tree node is being set
5263 * @dev2: device whose device-tree node is being reused
5264 *
5265 * Takes another reference to the new device-tree node after first dropping
5266 * any reference held to the old node.
5267 */
5268void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
5269{
5270	of_node_put(dev->of_node);
5271	dev->of_node = of_node_get(dev2->of_node);
5272	dev->of_node_reused = true;
5273}
5274EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
5275
5276void device_set_node(struct device *dev, struct fwnode_handle *fwnode)
5277{
5278	dev->fwnode = fwnode;
5279	dev->of_node = to_of_node(fwnode);
5280}
5281EXPORT_SYMBOL_GPL(device_set_node);
5282
5283/**
5284 * get_dev_from_fwnode - Obtain a reference count of the struct device the
5285 * struct fwnode_handle is associated with.
5286 * @fwnode: The pointer to the struct fwnode_handle to obtain the struct device
5287 * reference count of.
5288 *
5289 * This function obtains a reference count of the device the device pointer
5290 * embedded in the struct fwnode_handle points to.
5291 *
5292 * Note that the struct device pointer embedded in struct fwnode_handle does
5293 * *not* have a reference count of the struct device itself.
5294 *
5295 * Hence, it is a UAF (and thus a bug) to call this function if the caller can't
5296 * guarantee that the last reference count of the corresponding struct device is
5297 * not dropped concurrently.
5298 *
5299 * This is possible since struct fwnode_handle has its own reference count and
5300 * hence can out-live the struct device it is associated with.
5301 */
5302struct device *get_dev_from_fwnode(struct fwnode_handle *fwnode)
5303{
5304	return get_device((fwnode)->dev);
5305}
5306EXPORT_SYMBOL_GPL(get_dev_from_fwnode);
5307
5308int device_match_name(struct device *dev, const void *name)
5309{
5310	return sysfs_streq(dev_name(dev), name);
5311}
5312EXPORT_SYMBOL_GPL(device_match_name);
5313
5314int device_match_type(struct device *dev, const void *type)
5315{
5316	return dev->type == type;
5317}
5318EXPORT_SYMBOL_GPL(device_match_type);
5319
5320int device_match_of_node(struct device *dev, const void *np)
5321{
5322	return np && dev->of_node == np;
5323}
5324EXPORT_SYMBOL_GPL(device_match_of_node);
5325
5326int device_match_fwnode(struct device *dev, const void *fwnode)
5327{
5328	return fwnode && dev_fwnode(dev) == fwnode;
5329}
5330EXPORT_SYMBOL_GPL(device_match_fwnode);
5331
5332int device_match_devt(struct device *dev, const void *pdevt)
5333{
5334	return dev->devt == *(dev_t *)pdevt;
5335}
5336EXPORT_SYMBOL_GPL(device_match_devt);
5337
5338int device_match_acpi_dev(struct device *dev, const void *adev)
5339{
5340	return adev && ACPI_COMPANION(dev) == adev;
5341}
5342EXPORT_SYMBOL(device_match_acpi_dev);
5343
5344int device_match_acpi_handle(struct device *dev, const void *handle)
5345{
5346	return handle && ACPI_HANDLE(dev) == handle;
5347}
5348EXPORT_SYMBOL(device_match_acpi_handle);
5349
5350int device_match_any(struct device *dev, const void *unused)
5351{
5352	return 1;
5353}
5354EXPORT_SYMBOL_GPL(device_match_any);