1/*
   2 * Procedures for creating, accessing and interpreting the device tree.
   3 *
   4 * Paul Mackerras	August 1996.
   5 * Copyright (C) 1996-2005 Paul Mackerras.
   6 *
   7 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
   8 *    {engebret|bergner}@us.ibm.com
   9 *
  10 *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
  11 *
  12 *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
  13 *  Grant Likely.
  14 *
  15 *      This program is free software; you can redistribute it and/or
  16 *      modify it under the terms of the GNU General Public License
  17 *      as published by the Free Software Foundation; either version
  18 *      2 of the License, or (at your option) any later version.
  19 */
  20#include <linux/console.h>
  21#include <linux/ctype.h>
  22#include <linux/cpu.h>
  23#include <linux/module.h>
  24#include <linux/of.h>
  25#include <linux/of_graph.h>
  26#include <linux/spinlock.h>
  27#include <linux/slab.h>
  28#include <linux/string.h>
  29#include <linux/proc_fs.h>
  30
  31#include "of_private.h"
  32
  33LIST_HEAD(aliases_lookup);
  34
  35struct device_node *of_root;
  36EXPORT_SYMBOL(of_root);
  37struct device_node *of_chosen;
  38struct device_node *of_aliases;
  39struct device_node *of_stdout;
  40static const char *of_stdout_options;
  41
  42struct kset *of_kset;
  43
  44/*
  45 * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
  46 * This mutex must be held whenever modifications are being made to the
  47 * device tree. The of_{attach,detach}_node() and
  48 * of_{add,remove,update}_property() helpers make sure this happens.
  49 */
  50DEFINE_MUTEX(of_mutex);
  51
  52/* use when traversing tree through the child, sibling,
  53 * or parent members of struct device_node.
  54 */
  55DEFINE_RAW_SPINLOCK(devtree_lock);
  56
  57int of_n_addr_cells(struct device_node *np)
  58{
  59	const __be32 *ip;
  60
  61	do {
  62		if (np->parent)
  63			np = np->parent;
  64		ip = of_get_property(np, "#address-cells", NULL);
  65		if (ip)
  66			return be32_to_cpup(ip);
  67	} while (np->parent);
  68	/* No #address-cells property for the root node */
  69	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  70}
  71EXPORT_SYMBOL(of_n_addr_cells);
  72
  73int of_n_size_cells(struct device_node *np)
  74{
  75	const __be32 *ip;
  76
  77	do {
  78		if (np->parent)
  79			np = np->parent;
  80		ip = of_get_property(np, "#size-cells", NULL);
  81		if (ip)
  82			return be32_to_cpup(ip);
  83	} while (np->parent);
  84	/* No #size-cells property for the root node */
  85	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  86}
  87EXPORT_SYMBOL(of_n_size_cells);
  88
  89#ifdef CONFIG_NUMA
  90int __weak of_node_to_nid(struct device_node *np)
  91{
  92	return NUMA_NO_NODE;
  93}
  94#endif
  95
  96#ifndef CONFIG_OF_DYNAMIC
  97static void of_node_release(struct kobject *kobj)
  98{
  99	/* Without CONFIG_OF_DYNAMIC, no nodes gets freed */
 100}
 101#endif /* CONFIG_OF_DYNAMIC */
 102
 103struct kobj_type of_node_ktype = {
 104	.release = of_node_release,
 105};
 106
 107static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
 108				struct bin_attribute *bin_attr, char *buf,
 109				loff_t offset, size_t count)
 110{
 111	struct property *pp = container_of(bin_attr, struct property, attr);
 112	return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
 113}
 114
 115static const char *safe_name(struct kobject *kobj, const char *orig_name)
 116{
 117	const char *name = orig_name;
 118	struct kernfs_node *kn;
 119	int i = 0;
 120
 121	/* don't be a hero. After 16 tries give up */
 122	while (i < 16 && (kn = sysfs_get_dirent(kobj->sd, name))) {
 123		sysfs_put(kn);
 124		if (name != orig_name)
 125			kfree(name);
 126		name = kasprintf(GFP_KERNEL, "%s#%i", orig_name, ++i);
 127	}
 128
 129	if (name != orig_name)
 130		pr_warn("device-tree: Duplicate name in %s, renamed to \"%s\"\n",
 131			kobject_name(kobj), name);
 132	return name;
 133}
 134
 135int __of_add_property_sysfs(struct device_node *np, struct property *pp)
 136{
 137	int rc;
 138
 139	/* Important: Don't leak passwords */
 140	bool secure = strncmp(pp->name, "security-", 9) == 0;
 141
 142	if (!IS_ENABLED(CONFIG_SYSFS))
 143		return 0;
 144
 145	if (!of_kset || !of_node_is_attached(np))
 146		return 0;
 147
 148	sysfs_bin_attr_init(&pp->attr);
 149	pp->attr.attr.name = safe_name(&np->kobj, pp->name);
 150	pp->attr.attr.mode = secure ? S_IRUSR : S_IRUGO;
 151	pp->attr.size = secure ? 0 : pp->length;
 152	pp->attr.read = of_node_property_read;
 153
 154	rc = sysfs_create_bin_file(&np->kobj, &pp->attr);
 155	WARN(rc, "error adding attribute %s to node %s\n", pp->name, np->full_name);
 156	return rc;
 157}
 158
 159int __of_attach_node_sysfs(struct device_node *np)
 160{
 161	const char *name;
 162	struct property *pp;
 163	int rc;
 164
 165	if (!IS_ENABLED(CONFIG_SYSFS))
 166		return 0;
 167
 168	if (!of_kset)
 169		return 0;
 170
 171	np->kobj.kset = of_kset;
 172	if (!np->parent) {
 173		/* Nodes without parents are new top level trees */
 174		rc = kobject_add(&np->kobj, NULL, "%s",
 175				 safe_name(&of_kset->kobj, "base"));
 176	} else {
 177		name = safe_name(&np->parent->kobj, kbasename(np->full_name));
 178		if (!name || !name[0])
 179			return -EINVAL;
 180
 181		rc = kobject_add(&np->kobj, &np->parent->kobj, "%s", name);
 182	}
 183	if (rc)
 184		return rc;
 185
 186	for_each_property_of_node(np, pp)
 187		__of_add_property_sysfs(np, pp);
 188
 189	return 0;
 190}
 191
 192void __init of_core_init(void)
 193{
 194	struct device_node *np;
 195
 196	/* Create the kset, and register existing nodes */
 197	mutex_lock(&of_mutex);
 198	of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
 199	if (!of_kset) {
 200		mutex_unlock(&of_mutex);
 201		pr_err("devicetree: failed to register existing nodes\n");
 202		return;
 203	}
 204	for_each_of_allnodes(np)
 205		__of_attach_node_sysfs(np);
 206	mutex_unlock(&of_mutex);
 207
 208	/* Symlink in /proc as required by userspace ABI */
 209	if (of_root)
 210		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
 211}
 212
 213static struct property *__of_find_property(const struct device_node *np,
 214					   const char *name, int *lenp)
 215{
 216	struct property *pp;
 217
 218	if (!np)
 219		return NULL;
 220
 221	for (pp = np->properties; pp; pp = pp->next) {
 222		if (of_prop_cmp(pp->name, name) == 0) {
 223			if (lenp)
 224				*lenp = pp->length;
 225			break;
 226		}
 227	}
 228
 229	return pp;
 230}
 231
 232struct property *of_find_property(const struct device_node *np,
 233				  const char *name,
 234				  int *lenp)
 235{
 236	struct property *pp;
 237	unsigned long flags;
 238
 239	raw_spin_lock_irqsave(&devtree_lock, flags);
 240	pp = __of_find_property(np, name, lenp);
 241	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 242
 243	return pp;
 244}
 245EXPORT_SYMBOL(of_find_property);
 246
 247struct device_node *__of_find_all_nodes(struct device_node *prev)
 248{
 249	struct device_node *np;
 250	if (!prev) {
 251		np = of_root;
 252	} else if (prev->child) {
 253		np = prev->child;
 254	} else {
 255		/* Walk back up looking for a sibling, or the end of the structure */
 256		np = prev;
 257		while (np->parent && !np->sibling)
 258			np = np->parent;
 259		np = np->sibling; /* Might be null at the end of the tree */
 260	}
 261	return np;
 262}
 263
 264/**
 265 * of_find_all_nodes - Get next node in global list
 266 * @prev:	Previous node or NULL to start iteration
 267 *		of_node_put() will be called on it
 268 *
 269 * Returns a node pointer with refcount incremented, use
 270 * of_node_put() on it when done.
 271 */
 272struct device_node *of_find_all_nodes(struct device_node *prev)
 273{
 274	struct device_node *np;
 275	unsigned long flags;
 276
 277	raw_spin_lock_irqsave(&devtree_lock, flags);
 278	np = __of_find_all_nodes(prev);
 279	of_node_get(np);
 280	of_node_put(prev);
 281	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 282	return np;
 283}
 284EXPORT_SYMBOL(of_find_all_nodes);
 285
 286/*
 287 * Find a property with a given name for a given node
 288 * and return the value.
 289 */
 290const void *__of_get_property(const struct device_node *np,
 291			      const char *name, int *lenp)
 292{
 293	struct property *pp = __of_find_property(np, name, lenp);
 294
 295	return pp ? pp->value : NULL;
 296}
 297
 298/*
 299 * Find a property with a given name for a given node
 300 * and return the value.
 301 */
 302const void *of_get_property(const struct device_node *np, const char *name,
 303			    int *lenp)
 304{
 305	struct property *pp = of_find_property(np, name, lenp);
 306
 307	return pp ? pp->value : NULL;
 308}
 309EXPORT_SYMBOL(of_get_property);
 310
 311/*
 312 * arch_match_cpu_phys_id - Match the given logical CPU and physical id
 313 *
 314 * @cpu: logical cpu index of a core/thread
 315 * @phys_id: physical identifier of a core/thread
 316 *
 317 * CPU logical to physical index mapping is architecture specific.
 318 * However this __weak function provides a default match of physical
 319 * id to logical cpu index. phys_id provided here is usually values read
 320 * from the device tree which must match the hardware internal registers.
 321 *
 322 * Returns true if the physical identifier and the logical cpu index
 323 * correspond to the same core/thread, false otherwise.
 324 */
 325bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
 326{
 327	return (u32)phys_id == cpu;
 328}
 329
 330/**
 331 * Checks if the given "prop_name" property holds the physical id of the
 332 * core/thread corresponding to the logical cpu 'cpu'. If 'thread' is not
 333 * NULL, local thread number within the core is returned in it.
 334 */
 335static bool __of_find_n_match_cpu_property(struct device_node *cpun,
 336			const char *prop_name, int cpu, unsigned int *thread)
 337{
 338	const __be32 *cell;
 339	int ac, prop_len, tid;
 340	u64 hwid;
 341
 342	ac = of_n_addr_cells(cpun);
 343	cell = of_get_property(cpun, prop_name, &prop_len);
 344	if (!cell || !ac)
 345		return false;
 346	prop_len /= sizeof(*cell) * ac;
 347	for (tid = 0; tid < prop_len; tid++) {
 348		hwid = of_read_number(cell, ac);
 349		if (arch_match_cpu_phys_id(cpu, hwid)) {
 350			if (thread)
 351				*thread = tid;
 352			return true;
 353		}
 354		cell += ac;
 355	}
 356	return false;
 357}
 358
 359/*
 360 * arch_find_n_match_cpu_physical_id - See if the given device node is
 361 * for the cpu corresponding to logical cpu 'cpu'.  Return true if so,
 362 * else false.  If 'thread' is non-NULL, the local thread number within the
 363 * core is returned in it.
 364 */
 365bool __weak arch_find_n_match_cpu_physical_id(struct device_node *cpun,
 366					      int cpu, unsigned int *thread)
 367{
 368	/* Check for non-standard "ibm,ppc-interrupt-server#s" property
 369	 * for thread ids on PowerPC. If it doesn't exist fallback to
 370	 * standard "reg" property.
 371	 */
 372	if (IS_ENABLED(CONFIG_PPC) &&
 373	    __of_find_n_match_cpu_property(cpun,
 374					   "ibm,ppc-interrupt-server#s",
 375					   cpu, thread))
 376		return true;
 377
 378	return __of_find_n_match_cpu_property(cpun, "reg", cpu, thread);
 379}
 380
 381/**
 382 * of_get_cpu_node - Get device node associated with the given logical CPU
 383 *
 384 * @cpu: CPU number(logical index) for which device node is required
 385 * @thread: if not NULL, local thread number within the physical core is
 386 *          returned
 387 *
 388 * The main purpose of this function is to retrieve the device node for the
 389 * given logical CPU index. It should be used to initialize the of_node in
 390 * cpu device. Once of_node in cpu device is populated, all the further
 391 * references can use that instead.
 392 *
 393 * CPU logical to physical index mapping is architecture specific and is built
 394 * before booting secondary cores. This function uses arch_match_cpu_phys_id
 395 * which can be overridden by architecture specific implementation.
 396 *
 397 * Returns a node pointer for the logical cpu if found, else NULL.
 398 */
 399struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
 400{
 401	struct device_node *cpun;
 402
 403	for_each_node_by_type(cpun, "cpu") {
 404		if (arch_find_n_match_cpu_physical_id(cpun, cpu, thread))
 405			return cpun;
 406	}
 407	return NULL;
 408}
 409EXPORT_SYMBOL(of_get_cpu_node);
 410
 411/**
 412 * __of_device_is_compatible() - Check if the node matches given constraints
 413 * @device: pointer to node
 414 * @compat: required compatible string, NULL or "" for any match
 415 * @type: required device_type value, NULL or "" for any match
 416 * @name: required node name, NULL or "" for any match
 417 *
 418 * Checks if the given @compat, @type and @name strings match the
 419 * properties of the given @device. A constraints can be skipped by
 420 * passing NULL or an empty string as the constraint.
 421 *
 422 * Returns 0 for no match, and a positive integer on match. The return
 423 * value is a relative score with larger values indicating better
 424 * matches. The score is weighted for the most specific compatible value
 425 * to get the highest score. Matching type is next, followed by matching
 426 * name. Practically speaking, this results in the following priority
 427 * order for matches:
 428 *
 429 * 1. specific compatible && type && name
 430 * 2. specific compatible && type
 431 * 3. specific compatible && name
 432 * 4. specific compatible
 433 * 5. general compatible && type && name
 434 * 6. general compatible && type
 435 * 7. general compatible && name
 436 * 8. general compatible
 437 * 9. type && name
 438 * 10. type
 439 * 11. name
 440 */
 441static int __of_device_is_compatible(const struct device_node *device,
 442				     const char *compat, const char *type, const char *name)
 443{
 444	struct property *prop;
 445	const char *cp;
 446	int index = 0, score = 0;
 447
 448	/* Compatible match has highest priority */
 449	if (compat && compat[0]) {
 450		prop = __of_find_property(device, "compatible", NULL);
 451		for (cp = of_prop_next_string(prop, NULL); cp;
 452		     cp = of_prop_next_string(prop, cp), index++) {
 453			if (of_compat_cmp(cp, compat, strlen(compat)) == 0) {
 454				score = INT_MAX/2 - (index << 2);
 455				break;
 456			}
 457		}
 458		if (!score)
 459			return 0;
 460	}
 461
 462	/* Matching type is better than matching name */
 463	if (type && type[0]) {
 464		if (!device->type || of_node_cmp(type, device->type))
 465			return 0;
 466		score += 2;
 467	}
 468
 469	/* Matching name is a bit better than not */
 470	if (name && name[0]) {
 471		if (!device->name || of_node_cmp(name, device->name))
 472			return 0;
 473		score++;
 474	}
 475
 476	return score;
 477}
 478
 479/** Checks if the given "compat" string matches one of the strings in
 480 * the device's "compatible" property
 481 */
 482int of_device_is_compatible(const struct device_node *device,
 483		const char *compat)
 484{
 485	unsigned long flags;
 486	int res;
 487
 488	raw_spin_lock_irqsave(&devtree_lock, flags);
 489	res = __of_device_is_compatible(device, compat, NULL, NULL);
 490	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 491	return res;
 492}
 493EXPORT_SYMBOL(of_device_is_compatible);
 494
 495/**
 496 * of_machine_is_compatible - Test root of device tree for a given compatible value
 497 * @compat: compatible string to look for in root node's compatible property.
 498 *
 499 * Returns a positive integer if the root node has the given value in its
 500 * compatible property.
 501 */
 502int of_machine_is_compatible(const char *compat)
 503{
 504	struct device_node *root;
 505	int rc = 0;
 506
 507	root = of_find_node_by_path("/");
 508	if (root) {
 509		rc = of_device_is_compatible(root, compat);
 510		of_node_put(root);
 511	}
 512	return rc;
 513}
 514EXPORT_SYMBOL(of_machine_is_compatible);
 515
 516/**
 517 *  __of_device_is_available - check if a device is available for use
 518 *
 519 *  @device: Node to check for availability, with locks already held
 520 *
 521 *  Returns true if the status property is absent or set to "okay" or "ok",
 522 *  false otherwise
 523 */
 524static bool __of_device_is_available(const struct device_node *device)
 525{
 526	const char *status;
 527	int statlen;
 528
 529	if (!device)
 530		return false;
 531
 532	status = __of_get_property(device, "status", &statlen);
 533	if (status == NULL)
 534		return true;
 535
 536	if (statlen > 0) {
 537		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
 538			return true;
 539	}
 540
 541	return false;
 542}
 543
 544/**
 545 *  of_device_is_available - check if a device is available for use
 546 *
 547 *  @device: Node to check for availability
 548 *
 549 *  Returns true if the status property is absent or set to "okay" or "ok",
 550 *  false otherwise
 551 */
 552bool of_device_is_available(const struct device_node *device)
 553{
 554	unsigned long flags;
 555	bool res;
 556
 557	raw_spin_lock_irqsave(&devtree_lock, flags);
 558	res = __of_device_is_available(device);
 559	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 560	return res;
 561
 562}
 563EXPORT_SYMBOL(of_device_is_available);
 564
 565/**
 566 *  of_device_is_big_endian - check if a device has BE registers
 567 *
 568 *  @device: Node to check for endianness
 569 *
 570 *  Returns true if the device has a "big-endian" property, or if the kernel
 571 *  was compiled for BE *and* the device has a "native-endian" property.
 572 *  Returns false otherwise.
 573 *
 574 *  Callers would nominally use ioread32be/iowrite32be if
 575 *  of_device_is_big_endian() == true, or readl/writel otherwise.
 576 */
 577bool of_device_is_big_endian(const struct device_node *device)
 578{
 579	if (of_property_read_bool(device, "big-endian"))
 580		return true;
 581	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
 582	    of_property_read_bool(device, "native-endian"))
 583		return true;
 584	return false;
 585}
 586EXPORT_SYMBOL(of_device_is_big_endian);
 587
 588/**
 589 *	of_get_parent - Get a node's parent if any
 590 *	@node:	Node to get parent
 591 *
 592 *	Returns a node pointer with refcount incremented, use
 593 *	of_node_put() on it when done.
 594 */
 595struct device_node *of_get_parent(const struct device_node *node)
 596{
 597	struct device_node *np;
 598	unsigned long flags;
 599
 600	if (!node)
 601		return NULL;
 602
 603	raw_spin_lock_irqsave(&devtree_lock, flags);
 604	np = of_node_get(node->parent);
 605	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 606	return np;
 607}
 608EXPORT_SYMBOL(of_get_parent);
 609
 610/**
 611 *	of_get_next_parent - Iterate to a node's parent
 612 *	@node:	Node to get parent of
 613 *
 614 *	This is like of_get_parent() except that it drops the
 615 *	refcount on the passed node, making it suitable for iterating
 616 *	through a node's parents.
 617 *
 618 *	Returns a node pointer with refcount incremented, use
 619 *	of_node_put() on it when done.
 620 */
 621struct device_node *of_get_next_parent(struct device_node *node)
 622{
 623	struct device_node *parent;
 624	unsigned long flags;
 625
 626	if (!node)
 627		return NULL;
 628
 629	raw_spin_lock_irqsave(&devtree_lock, flags);
 630	parent = of_node_get(node->parent);
 631	of_node_put(node);
 632	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 633	return parent;
 634}
 635EXPORT_SYMBOL(of_get_next_parent);
 636
 637static struct device_node *__of_get_next_child(const struct device_node *node,
 638						struct device_node *prev)
 639{
 640	struct device_node *next;
 641
 642	if (!node)
 643		return NULL;
 644
 645	next = prev ? prev->sibling : node->child;
 646	for (; next; next = next->sibling)
 647		if (of_node_get(next))
 648			break;
 649	of_node_put(prev);
 650	return next;
 651}
 652#define __for_each_child_of_node(parent, child) \
 653	for (child = __of_get_next_child(parent, NULL); child != NULL; \
 654	     child = __of_get_next_child(parent, child))
 655
 656/**
 657 *	of_get_next_child - Iterate a node childs
 658 *	@node:	parent node
 659 *	@prev:	previous child of the parent node, or NULL to get first
 660 *
 661 *	Returns a node pointer with refcount incremented, use of_node_put() on
 662 *	it when done. Returns NULL when prev is the last child. Decrements the
 663 *	refcount of prev.
 664 */
 665struct device_node *of_get_next_child(const struct device_node *node,
 666	struct device_node *prev)
 667{
 668	struct device_node *next;
 669	unsigned long flags;
 670
 671	raw_spin_lock_irqsave(&devtree_lock, flags);
 672	next = __of_get_next_child(node, prev);
 673	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 674	return next;
 675}
 676EXPORT_SYMBOL(of_get_next_child);
 677
 678/**
 679 *	of_get_next_available_child - Find the next available child node
 680 *	@node:	parent node
 681 *	@prev:	previous child of the parent node, or NULL to get first
 682 *
 683 *      This function is like of_get_next_child(), except that it
 684 *      automatically skips any disabled nodes (i.e. status = "disabled").
 685 */
 686struct device_node *of_get_next_available_child(const struct device_node *node,
 687	struct device_node *prev)
 688{
 689	struct device_node *next;
 690	unsigned long flags;
 691
 692	if (!node)
 693		return NULL;
 694
 695	raw_spin_lock_irqsave(&devtree_lock, flags);
 696	next = prev ? prev->sibling : node->child;
 697	for (; next; next = next->sibling) {
 698		if (!__of_device_is_available(next))
 699			continue;
 700		if (of_node_get(next))
 701			break;
 702	}
 703	of_node_put(prev);
 704	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 705	return next;
 706}
 707EXPORT_SYMBOL(of_get_next_available_child);
 708
 709/**
 710 *	of_get_child_by_name - Find the child node by name for a given parent
 711 *	@node:	parent node
 712 *	@name:	child name to look for.
 713 *
 714 *      This function looks for child node for given matching name
 715 *
 716 *	Returns a node pointer if found, with refcount incremented, use
 717 *	of_node_put() on it when done.
 718 *	Returns NULL if node is not found.
 719 */
 720struct device_node *of_get_child_by_name(const struct device_node *node,
 721				const char *name)
 722{
 723	struct device_node *child;
 724
 725	for_each_child_of_node(node, child)
 726		if (child->name && (of_node_cmp(child->name, name) == 0))
 727			break;
 728	return child;
 729}
 730EXPORT_SYMBOL(of_get_child_by_name);
 731
 732static struct device_node *__of_find_node_by_path(struct device_node *parent,
 733						const char *path)
 734{
 735	struct device_node *child;
 736	int len;
 737
 738	len = strcspn(path, "/:");
 739	if (!len)
 740		return NULL;
 741
 742	__for_each_child_of_node(parent, child) {
 743		const char *name = strrchr(child->full_name, '/');
 744		if (WARN(!name, "malformed device_node %s\n", child->full_name))
 745			continue;
 746		name++;
 747		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
 748			return child;
 749	}
 750	return NULL;
 751}
 752
 753/**
 754 *	of_find_node_opts_by_path - Find a node matching a full OF path
 755 *	@path: Either the full path to match, or if the path does not
 756 *	       start with '/', the name of a property of the /aliases
 757 *	       node (an alias).  In the case of an alias, the node
 758 *	       matching the alias' value will be returned.
 759 *	@opts: Address of a pointer into which to store the start of
 760 *	       an options string appended to the end of the path with
 761 *	       a ':' separator.
 762 *
 763 *	Valid paths:
 764 *		/foo/bar	Full path
 765 *		foo		Valid alias
 766 *		foo/bar		Valid alias + relative path
 767 *
 768 *	Returns a node pointer with refcount incremented, use
 769 *	of_node_put() on it when done.
 770 */
 771struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)
 772{
 773	struct device_node *np = NULL;
 774	struct property *pp;
 775	unsigned long flags;
 776	const char *separator = strchr(path, ':');
 777
 778	if (opts)
 779		*opts = separator ? separator + 1 : NULL;
 780
 781	if (strcmp(path, "/") == 0)
 782		return of_node_get(of_root);
 783
 784	/* The path could begin with an alias */
 785	if (*path != '/') {
 786		int len;
 787		const char *p = separator;
 788
 789		if (!p)
 790			p = strchrnul(path, '/');
 791		len = p - path;
 792
 793		/* of_aliases must not be NULL */
 794		if (!of_aliases)
 795			return NULL;
 796
 797		for_each_property_of_node(of_aliases, pp) {
 798			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
 799				np = of_find_node_by_path(pp->value);
 800				break;
 801			}
 802		}
 803		if (!np)
 804			return NULL;
 805		path = p;
 806	}
 807
 808	/* Step down the tree matching path components */
 809	raw_spin_lock_irqsave(&devtree_lock, flags);
 810	if (!np)
 811		np = of_node_get(of_root);
 812	while (np && *path == '/') {
 813		path++; /* Increment past '/' delimiter */
 814		np = __of_find_node_by_path(np, path);
 815		path = strchrnul(path, '/');
 816		if (separator && separator < path)
 817			break;
 818	}
 819	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 820	return np;
 821}
 822EXPORT_SYMBOL(of_find_node_opts_by_path);
 823
 824/**
 825 *	of_find_node_by_name - Find a node by its "name" property
 826 *	@from:	The node to start searching from or NULL, the node
 827 *		you pass will not be searched, only the next one
 828 *		will; typically, you pass what the previous call
 829 *		returned. of_node_put() will be called on it
 830 *	@name:	The name string to match against
 831 *
 832 *	Returns a node pointer with refcount incremented, use
 833 *	of_node_put() on it when done.
 834 */
 835struct device_node *of_find_node_by_name(struct device_node *from,
 836	const char *name)
 837{
 838	struct device_node *np;
 839	unsigned long flags;
 840
 841	raw_spin_lock_irqsave(&devtree_lock, flags);
 842	for_each_of_allnodes_from(from, np)
 843		if (np->name && (of_node_cmp(np->name, name) == 0)
 844		    && of_node_get(np))
 845			break;
 846	of_node_put(from);
 847	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 848	return np;
 849}
 850EXPORT_SYMBOL(of_find_node_by_name);
 851
 852/**
 853 *	of_find_node_by_type - Find a node by its "device_type" property
 854 *	@from:	The node to start searching from, or NULL to start searching
 855 *		the entire device tree. The node you pass will not be
 856 *		searched, only the next one will; typically, you pass
 857 *		what the previous call returned. of_node_put() will be
 858 *		called on from for you.
 859 *	@type:	The type string to match against
 860 *
 861 *	Returns a node pointer with refcount incremented, use
 862 *	of_node_put() on it when done.
 863 */
 864struct device_node *of_find_node_by_type(struct device_node *from,
 865	const char *type)
 866{
 867	struct device_node *np;
 868	unsigned long flags;
 869
 870	raw_spin_lock_irqsave(&devtree_lock, flags);
 871	for_each_of_allnodes_from(from, np)
 872		if (np->type && (of_node_cmp(np->type, type) == 0)
 873		    && of_node_get(np))
 874			break;
 875	of_node_put(from);
 876	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 877	return np;
 878}
 879EXPORT_SYMBOL(of_find_node_by_type);
 880
 881/**
 882 *	of_find_compatible_node - Find a node based on type and one of the
 883 *                                tokens in its "compatible" property
 884 *	@from:		The node to start searching from or NULL, the node
 885 *			you pass will not be searched, only the next one
 886 *			will; typically, you pass what the previous call
 887 *			returned. of_node_put() will be called on it
 888 *	@type:		The type string to match "device_type" or NULL to ignore
 889 *	@compatible:	The string to match to one of the tokens in the device
 890 *			"compatible" list.
 891 *
 892 *	Returns a node pointer with refcount incremented, use
 893 *	of_node_put() on it when done.
 894 */
 895struct device_node *of_find_compatible_node(struct device_node *from,
 896	const char *type, const char *compatible)
 897{
 898	struct device_node *np;
 899	unsigned long flags;
 900
 901	raw_spin_lock_irqsave(&devtree_lock, flags);
 902	for_each_of_allnodes_from(from, np)
 903		if (__of_device_is_compatible(np, compatible, type, NULL) &&
 904		    of_node_get(np))
 905			break;
 906	of_node_put(from);
 907	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 908	return np;
 909}
 910EXPORT_SYMBOL(of_find_compatible_node);
 911
 912/**
 913 *	of_find_node_with_property - Find a node which has a property with
 914 *                                   the given name.
 915 *	@from:		The node to start searching from or NULL, the node
 916 *			you pass will not be searched, only the next one
 917 *			will; typically, you pass what the previous call
 918 *			returned. of_node_put() will be called on it
 919 *	@prop_name:	The name of the property to look for.
 920 *
 921 *	Returns a node pointer with refcount incremented, use
 922 *	of_node_put() on it when done.
 923 */
 924struct device_node *of_find_node_with_property(struct device_node *from,
 925	const char *prop_name)
 926{
 927	struct device_node *np;
 928	struct property *pp;
 929	unsigned long flags;
 930
 931	raw_spin_lock_irqsave(&devtree_lock, flags);
 932	for_each_of_allnodes_from(from, np) {
 933		for (pp = np->properties; pp; pp = pp->next) {
 934			if (of_prop_cmp(pp->name, prop_name) == 0) {
 935				of_node_get(np);
 936				goto out;
 937			}
 938		}
 939	}
 940out:
 941	of_node_put(from);
 942	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 943	return np;
 944}
 945EXPORT_SYMBOL(of_find_node_with_property);
 946
 947static
 948const struct of_device_id *__of_match_node(const struct of_device_id *matches,
 949					   const struct device_node *node)
 950{
 951	const struct of_device_id *best_match = NULL;
 952	int score, best_score = 0;
 953
 954	if (!matches)
 955		return NULL;
 956
 957	for (; matches->name[0] || matches->type[0] || matches->compatible[0]; matches++) {
 958		score = __of_device_is_compatible(node, matches->compatible,
 959						  matches->type, matches->name);
 960		if (score > best_score) {
 961			best_match = matches;
 962			best_score = score;
 963		}
 964	}
 965
 966	return best_match;
 967}
 968
 969/**
 970 * of_match_node - Tell if a device_node has a matching of_match structure
 971 *	@matches:	array of of device match structures to search in
 972 *	@node:		the of device structure to match against
 973 *
 974 *	Low level utility function used by device matching.
 975 */
 976const struct of_device_id *of_match_node(const struct of_device_id *matches,
 977					 const struct device_node *node)
 978{
 979	const struct of_device_id *match;
 980	unsigned long flags;
 981
 982	raw_spin_lock_irqsave(&devtree_lock, flags);
 983	match = __of_match_node(matches, node);
 984	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 985	return match;
 986}
 987EXPORT_SYMBOL(of_match_node);
 988
 989/**
 990 *	of_find_matching_node_and_match - Find a node based on an of_device_id
 991 *					  match table.
 992 *	@from:		The node to start searching from or NULL, the node
 993 *			you pass will not be searched, only the next one
 994 *			will; typically, you pass what the previous call
 995 *			returned. of_node_put() will be called on it
 996 *	@matches:	array of of device match structures to search in
 997 *	@match		Updated to point at the matches entry which matched
 998 *
 999 *	Returns a node pointer with refcount incremented, use
1000 *	of_node_put() on it when done.
1001 */
1002struct device_node *of_find_matching_node_and_match(struct device_node *from,
1003					const struct of_device_id *matches,
1004					const struct of_device_id **match)
1005{
1006	struct device_node *np;
1007	const struct of_device_id *m;
1008	unsigned long flags;
1009
1010	if (match)
1011		*match = NULL;
1012
1013	raw_spin_lock_irqsave(&devtree_lock, flags);
1014	for_each_of_allnodes_from(from, np) {
1015		m = __of_match_node(matches, np);
1016		if (m && of_node_get(np)) {
1017			if (match)
1018				*match = m;
1019			break;
1020		}
1021	}
1022	of_node_put(from);
1023	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1024	return np;
1025}
1026EXPORT_SYMBOL(of_find_matching_node_and_match);
1027
1028/**
1029 * of_modalias_node - Lookup appropriate modalias for a device node
1030 * @node:	pointer to a device tree node
1031 * @modalias:	Pointer to buffer that modalias value will be copied into
1032 * @len:	Length of modalias value
1033 *
1034 * Based on the value of the compatible property, this routine will attempt
1035 * to choose an appropriate modalias value for a particular device tree node.
1036 * It does this by stripping the manufacturer prefix (as delimited by a ',')
1037 * from the first entry in the compatible list property.
1038 *
1039 * This routine returns 0 on success, <0 on failure.
1040 */
1041int of_modalias_node(struct device_node *node, char *modalias, int len)
1042{
1043	const char *compatible, *p;
1044	int cplen;
1045
1046	compatible = of_get_property(node, "compatible", &cplen);
1047	if (!compatible || strlen(compatible) > cplen)
1048		return -ENODEV;
1049	p = strchr(compatible, ',');
1050	strlcpy(modalias, p ? p + 1 : compatible, len);
1051	return 0;
1052}
1053EXPORT_SYMBOL_GPL(of_modalias_node);
1054
1055/**
1056 * of_find_node_by_phandle - Find a node given a phandle
1057 * @handle:	phandle of the node to find
1058 *
1059 * Returns a node pointer with refcount incremented, use
1060 * of_node_put() on it when done.
1061 */
1062struct device_node *of_find_node_by_phandle(phandle handle)
1063{
1064	struct device_node *np;
1065	unsigned long flags;
1066
1067	if (!handle)
1068		return NULL;
1069
1070	raw_spin_lock_irqsave(&devtree_lock, flags);
1071	for_each_of_allnodes(np)
1072		if (np->phandle == handle)
1073			break;
1074	of_node_get(np);
1075	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1076	return np;
1077}
1078EXPORT_SYMBOL(of_find_node_by_phandle);
1079
1080/**
1081 * of_property_count_elems_of_size - Count the number of elements in a property
1082 *
1083 * @np:		device node from which the property value is to be read.
1084 * @propname:	name of the property to be searched.
1085 * @elem_size:	size of the individual element
1086 *
1087 * Search for a property in a device node and count the number of elements of
1088 * size elem_size in it. Returns number of elements on sucess, -EINVAL if the
1089 * property does not exist or its length does not match a multiple of elem_size
1090 * and -ENODATA if the property does not have a value.
1091 */
1092int of_property_count_elems_of_size(const struct device_node *np,
1093				const char *propname, int elem_size)
1094{
1095	struct property *prop = of_find_property(np, propname, NULL);
1096
1097	if (!prop)
1098		return -EINVAL;
1099	if (!prop->value)
1100		return -ENODATA;
1101
1102	if (prop->length % elem_size != 0) {
1103		pr_err("size of %s in node %s is not a multiple of %d\n",
1104		       propname, np->full_name, elem_size);
1105		return -EINVAL;
1106	}
1107
1108	return prop->length / elem_size;
1109}
1110EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);
1111
1112/**
1113 * of_find_property_value_of_size
1114 *
1115 * @np:		device node from which the property value is to be read.
1116 * @propname:	name of the property to be searched.
1117 * @len:	requested length of property value
1118 *
1119 * Search for a property in a device node and valid the requested size.
1120 * Returns the property value on success, -EINVAL if the property does not
1121 *  exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
1122 * property data isn't large enough.
1123 *
1124 */
1125static void *of_find_property_value_of_size(const struct device_node *np,
1126			const char *propname, u32 len)
1127{
1128	struct property *prop = of_find_property(np, propname, NULL);
1129
1130	if (!prop)
1131		return ERR_PTR(-EINVAL);
1132	if (!prop->value)
1133		return ERR_PTR(-ENODATA);
1134	if (len > prop->length)
1135		return ERR_PTR(-EOVERFLOW);
1136
1137	return prop->value;
1138}
1139
1140/**
1141 * of_property_read_u32_index - Find and read a u32 from a multi-value property.
1142 *
1143 * @np:		device node from which the property value is to be read.
1144 * @propname:	name of the property to be searched.
1145 * @index:	index of the u32 in the list of values
1146 * @out_value:	pointer to return value, modified only if no error.
1147 *
1148 * Search for a property in a device node and read nth 32-bit value from
1149 * it. Returns 0 on success, -EINVAL if the property does not exist,
1150 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1151 * property data isn't large enough.
1152 *
1153 * The out_value is modified only if a valid u32 value can be decoded.
1154 */
1155int of_property_read_u32_index(const struct device_node *np,
1156				       const char *propname,
1157				       u32 index, u32 *out_value)
1158{
1159	const u32 *val = of_find_property_value_of_size(np, propname,
1160					((index + 1) * sizeof(*out_value)));
1161
1162	if (IS_ERR(val))
1163		return PTR_ERR(val);
1164
1165	*out_value = be32_to_cpup(((__be32 *)val) + index);
1166	return 0;
1167}
1168EXPORT_SYMBOL_GPL(of_property_read_u32_index);
1169
1170/**
1171 * of_property_read_u8_array - Find and read an array of u8 from a property.
1172 *
1173 * @np:		device node from which the property value is to be read.
1174 * @propname:	name of the property to be searched.
1175 * @out_values:	pointer to return value, modified only if return value is 0.
1176 * @sz:		number of array elements to read
1177 *
1178 * Search for a property in a device node and read 8-bit value(s) from
1179 * it. Returns 0 on success, -EINVAL if the property does not exist,
1180 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1181 * property data isn't large enough.
1182 *
1183 * dts entry of array should be like:
1184 *	property = /bits/ 8 <0x50 0x60 0x70>;
1185 *
1186 * The out_values is modified only if a valid u8 value can be decoded.
1187 */
1188int of_property_read_u8_array(const struct device_node *np,
1189			const char *propname, u8 *out_values, size_t sz)
1190{
1191	const u8 *val = of_find_property_value_of_size(np, propname,
1192						(sz * sizeof(*out_values)));
1193
1194	if (IS_ERR(val))
1195		return PTR_ERR(val);
1196
1197	while (sz--)
1198		*out_values++ = *val++;
1199	return 0;
1200}
1201EXPORT_SYMBOL_GPL(of_property_read_u8_array);
1202
1203/**
1204 * of_property_read_u16_array - Find and read an array of u16 from a property.
1205 *
1206 * @np:		device node from which the property value is to be read.
1207 * @propname:	name of the property to be searched.
1208 * @out_values:	pointer to return value, modified only if return value is 0.
1209 * @sz:		number of array elements to read
1210 *
1211 * Search for a property in a device node and read 16-bit value(s) from
1212 * it. Returns 0 on success, -EINVAL if the property does not exist,
1213 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1214 * property data isn't large enough.
1215 *
1216 * dts entry of array should be like:
1217 *	property = /bits/ 16 <0x5000 0x6000 0x7000>;
1218 *
1219 * The out_values is modified only if a valid u16 value can be decoded.
1220 */
1221int of_property_read_u16_array(const struct device_node *np,
1222			const char *propname, u16 *out_values, size_t sz)
1223{
1224	const __be16 *val = of_find_property_value_of_size(np, propname,
1225						(sz * sizeof(*out_values)));
1226
1227	if (IS_ERR(val))
1228		return PTR_ERR(val);
1229
1230	while (sz--)
1231		*out_values++ = be16_to_cpup(val++);
1232	return 0;
1233}
1234EXPORT_SYMBOL_GPL(of_property_read_u16_array);
1235
1236/**
1237 * of_property_read_u32_array - Find and read an array of 32 bit integers
1238 * from a property.
1239 *
1240 * @np:		device node from which the property value is to be read.
1241 * @propname:	name of the property to be searched.
1242 * @out_values:	pointer to return value, modified only if return value is 0.
1243 * @sz:		number of array elements to read
1244 *
1245 * Search for a property in a device node and read 32-bit value(s) from
1246 * it. Returns 0 on success, -EINVAL if the property does not exist,
1247 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1248 * property data isn't large enough.
1249 *
1250 * The out_values is modified only if a valid u32 value can be decoded.
1251 */
1252int of_property_read_u32_array(const struct device_node *np,
1253			       const char *propname, u32 *out_values,
1254			       size_t sz)
1255{
1256	const __be32 *val = of_find_property_value_of_size(np, propname,
1257						(sz * sizeof(*out_values)));
1258
1259	if (IS_ERR(val))
1260		return PTR_ERR(val);
1261
1262	while (sz--)
1263		*out_values++ = be32_to_cpup(val++);
1264	return 0;
1265}
1266EXPORT_SYMBOL_GPL(of_property_read_u32_array);
1267
1268/**
1269 * of_property_read_u64 - Find and read a 64 bit integer from a property
1270 * @np:		device node from which the property value is to be read.
1271 * @propname:	name of the property to be searched.
1272 * @out_value:	pointer to return value, modified only if return value is 0.
1273 *
1274 * Search for a property in a device node and read a 64-bit value from
1275 * it. Returns 0 on success, -EINVAL if the property does not exist,
1276 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1277 * property data isn't large enough.
1278 *
1279 * The out_value is modified only if a valid u64 value can be decoded.
1280 */
1281int of_property_read_u64(const struct device_node *np, const char *propname,
1282			 u64 *out_value)
1283{
1284	const __be32 *val = of_find_property_value_of_size(np, propname,
1285						sizeof(*out_value));
1286
1287	if (IS_ERR(val))
1288		return PTR_ERR(val);
1289
1290	*out_value = of_read_number(val, 2);
1291	return 0;
1292}
1293EXPORT_SYMBOL_GPL(of_property_read_u64);
1294
1295/**
1296 * of_property_read_u64_array - Find and read an array of 64 bit integers
1297 * from a property.
1298 *
1299 * @np:		device node from which the property value is to be read.
1300 * @propname:	name of the property to be searched.
1301 * @out_values:	pointer to return value, modified only if return value is 0.
1302 * @sz:		number of array elements to read
1303 *
1304 * Search for a property in a device node and read 64-bit value(s) from
1305 * it. Returns 0 on success, -EINVAL if the property does not exist,
1306 * -ENODATA if property does not have a value, and -EOVERFLOW if the
1307 * property data isn't large enough.
1308 *
1309 * The out_values is modified only if a valid u64 value can be decoded.
1310 */
1311int of_property_read_u64_array(const struct device_node *np,
1312			       const char *propname, u64 *out_values,
1313			       size_t sz)
1314{
1315	const __be32 *val = of_find_property_value_of_size(np, propname,
1316						(sz * sizeof(*out_values)));
1317
1318	if (IS_ERR(val))
1319		return PTR_ERR(val);
1320
1321	while (sz--) {
1322		*out_values++ = of_read_number(val, 2);
1323		val += 2;
1324	}
1325	return 0;
1326}
1327EXPORT_SYMBOL_GPL(of_property_read_u64_array);
1328
1329/**
1330 * of_property_read_string - Find and read a string from a property
1331 * @np:		device node from which the property value is to be read.
1332 * @propname:	name of the property to be searched.
1333 * @out_string:	pointer to null terminated return string, modified only if
1334 *		return value is 0.
1335 *
1336 * Search for a property in a device tree node and retrieve a null
1337 * terminated string value (pointer to data, not a copy). Returns 0 on
1338 * success, -EINVAL if the property does not exist, -ENODATA if property
1339 * does not have a value, and -EILSEQ if the string is not null-terminated
1340 * within the length of the property data.
1341 *
1342 * The out_string pointer is modified only if a valid string can be decoded.
1343 */
1344int of_property_read_string(const struct device_node *np, const char *propname,
1345				const char **out_string)
1346{
1347	const struct property *prop = of_find_property(np, propname, NULL);
1348	if (!prop)
1349		return -EINVAL;
1350	if (!prop->value)
1351		return -ENODATA;
1352	if (strnlen(prop->value, prop->length) >= prop->length)
1353		return -EILSEQ;
1354	*out_string = prop->value;
1355	return 0;
1356}
1357EXPORT_SYMBOL_GPL(of_property_read_string);
1358
1359/**
1360 * of_property_match_string() - Find string in a list and return index
1361 * @np: pointer to node containing string list property
1362 * @propname: string list property name
1363 * @string: pointer to string to search for in string list
1364 *
1365 * This function searches a string list property and returns the index
1366 * of a specific string value.
1367 */
1368int of_property_match_string(const struct device_node *np, const char *propname,
1369			     const char *string)
1370{
1371	const struct property *prop = of_find_property(np, propname, NULL);
1372	size_t l;
1373	int i;
1374	const char *p, *end;
1375
1376	if (!prop)
1377		return -EINVAL;
1378	if (!prop->value)
1379		return -ENODATA;
1380
1381	p = prop->value;
1382	end = p + prop->length;
1383
1384	for (i = 0; p < end; i++, p += l) {
1385		l = strnlen(p, end - p) + 1;
1386		if (p + l > end)
1387			return -EILSEQ;
1388		pr_debug("comparing %s with %s\n", string, p);
1389		if (strcmp(string, p) == 0)
1390			return i; /* Found it; return index */
1391	}
1392	return -ENODATA;
1393}
1394EXPORT_SYMBOL_GPL(of_property_match_string);
1395
1396/**
1397 * of_property_read_string_helper() - Utility helper for parsing string properties
1398 * @np:		device node from which the property value is to be read.
1399 * @propname:	name of the property to be searched.
1400 * @out_strs:	output array of string pointers.
1401 * @sz:		number of array elements to read.
1402 * @skip:	Number of strings to skip over at beginning of list.
1403 *
1404 * Don't call this function directly. It is a utility helper for the
1405 * of_property_read_string*() family of functions.
1406 */
1407int of_property_read_string_helper(const struct device_node *np,
1408				   const char *propname, const char **out_strs,
1409				   size_t sz, int skip)
1410{
1411	const struct property *prop = of_find_property(np, propname, NULL);
1412	int l = 0, i = 0;
1413	const char *p, *end;
1414
1415	if (!prop)
1416		return -EINVAL;
1417	if (!prop->value)
1418		return -ENODATA;
1419	p = prop->value;
1420	end = p + prop->length;
1421
1422	for (i = 0; p < end && (!out_strs || i < skip + sz); i++, p += l) {
1423		l = strnlen(p, end - p) + 1;
1424		if (p + l > end)
1425			return -EILSEQ;
1426		if (out_strs && i >= skip)
1427			*out_strs++ = p;
1428	}
1429	i -= skip;
1430	return i <= 0 ? -ENODATA : i;
1431}
1432EXPORT_SYMBOL_GPL(of_property_read_string_helper);
1433
1434void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
1435{
1436	int i;
1437	printk("%s %s", msg, of_node_full_name(args->np));
1438	for (i = 0; i < args->args_count; i++)
1439		printk(i ? ",%08x" : ":%08x", args->args[i]);
1440	printk("\n");
1441}
1442
1443static int __of_parse_phandle_with_args(const struct device_node *np,
1444					const char *list_name,
1445					const char *cells_name,
1446					int cell_count, int index,
1447					struct of_phandle_args *out_args)
1448{
1449	const __be32 *list, *list_end;
1450	int rc = 0, size, cur_index = 0;
1451	uint32_t count = 0;
1452	struct device_node *node = NULL;
1453	phandle phandle;
1454
1455	/* Retrieve the phandle list property */
1456	list = of_get_property(np, list_name, &size);
1457	if (!list)
1458		return -ENOENT;
1459	list_end = list + size / sizeof(*list);
1460
1461	/* Loop over the phandles until all the requested entry is found */
1462	while (list < list_end) {
1463		rc = -EINVAL;
1464		count = 0;
1465
1466		/*
1467		 * If phandle is 0, then it is an empty entry with no
1468		 * arguments.  Skip forward to the next entry.
1469		 */
1470		phandle = be32_to_cpup(list++);
1471		if (phandle) {
1472			/*
1473			 * Find the provider node and parse the #*-cells
1474			 * property to determine the argument length.
1475			 *
1476			 * This is not needed if the cell count is hard-coded
1477			 * (i.e. cells_name not set, but cell_count is set),
1478			 * except when we're going to return the found node
1479			 * below.
1480			 */
1481			if (cells_name || cur_index == index) {
1482				node = of_find_node_by_phandle(phandle);
1483				if (!node) {
1484					pr_err("%s: could not find phandle\n",
1485						np->full_name);
1486					goto err;
1487				}
1488			}
1489
1490			if (cells_name) {
1491				if (of_property_read_u32(node, cells_name,
1492							 &count)) {
1493					pr_err("%s: could not get %s for %s\n",
1494						np->full_name, cells_name,
1495						node->full_name);
1496					goto err;
1497				}
1498			} else {
1499				count = cell_count;
1500			}
1501
1502			/*
1503			 * Make sure that the arguments actually fit in the
1504			 * remaining property data length
1505			 */
1506			if (list + count > list_end) {
1507				pr_err("%s: arguments longer than property\n",
1508					 np->full_name);
1509				goto err;
1510			}
1511		}
1512
1513		/*
1514		 * All of the error cases above bail out of the loop, so at
1515		 * this point, the parsing is successful. If the requested
1516		 * index matches, then fill the out_args structure and return,
1517		 * or return -ENOENT for an empty entry.
1518		 */
1519		rc = -ENOENT;
1520		if (cur_index == index) {
1521			if (!phandle)
1522				goto err;
1523
1524			if (out_args) {
1525				int i;
1526				if (WARN_ON(count > MAX_PHANDLE_ARGS))
1527					count = MAX_PHANDLE_ARGS;
1528				out_args->np = node;
1529				out_args->args_count = count;
1530				for (i = 0; i < count; i++)
1531					out_args->args[i] = be32_to_cpup(list++);
1532			} else {
1533				of_node_put(node);
1534			}
1535
1536			/* Found it! return success */
1537			return 0;
1538		}
1539
1540		of_node_put(node);
1541		node = NULL;
1542		list += count;
1543		cur_index++;
1544	}
1545
1546	/*
1547	 * Unlock node before returning result; will be one of:
1548	 * -ENOENT : index is for empty phandle
1549	 * -EINVAL : parsing error on data
1550	 * [1..n]  : Number of phandle (count mode; when index = -1)
1551	 */
1552	rc = index < 0 ? cur_index : -ENOENT;
1553 err:
1554	if (node)
1555		of_node_put(node);
1556	return rc;
1557}
1558
1559/**
1560 * of_parse_phandle - Resolve a phandle property to a device_node pointer
1561 * @np: Pointer to device node holding phandle property
1562 * @phandle_name: Name of property holding a phandle value
1563 * @index: For properties holding a table of phandles, this is the index into
1564 *         the table
1565 *
1566 * Returns the device_node pointer with refcount incremented.  Use
1567 * of_node_put() on it when done.
1568 */
1569struct device_node *of_parse_phandle(const struct device_node *np,
1570				     const char *phandle_name, int index)
1571{
1572	struct of_phandle_args args;
1573
1574	if (index < 0)
1575		return NULL;
1576
1577	if (__of_parse_phandle_with_args(np, phandle_name, NULL, 0,
1578					 index, &args))
1579		return NULL;
1580
1581	return args.np;
1582}
1583EXPORT_SYMBOL(of_parse_phandle);
1584
1585/**
1586 * of_parse_phandle_with_args() - Find a node pointed by phandle in a list
1587 * @np:		pointer to a device tree node containing a list
1588 * @list_name:	property name that contains a list
1589 * @cells_name:	property name that specifies phandles' arguments count
1590 * @index:	index of a phandle to parse out
1591 * @out_args:	optional pointer to output arguments structure (will be filled)
1592 *
1593 * This function is useful to parse lists of phandles and their arguments.
1594 * Returns 0 on success and fills out_args, on error returns appropriate
1595 * errno value.
1596 *
1597 * Caller is responsible to call of_node_put() on the returned out_args->np
1598 * pointer.
1599 *
1600 * Example:
1601 *
1602 * phandle1: node1 {
1603 *	#list-cells = <2>;
1604 * }
1605 *
1606 * phandle2: node2 {
1607 *	#list-cells = <1>;
1608 * }
1609 *
1610 * node3 {
1611 *	list = <&phandle1 1 2 &phandle2 3>;
1612 * }
1613 *
1614 * To get a device_node of the `node2' node you may call this:
1615 * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args);
1616 */
1617int of_parse_phandle_with_args(const struct device_node *np, const char *list_name,
1618				const char *cells_name, int index,
1619				struct of_phandle_args *out_args)
1620{
1621	if (index < 0)
1622		return -EINVAL;
1623	return __of_parse_phandle_with_args(np, list_name, cells_name, 0,
1624					    index, out_args);
1625}
1626EXPORT_SYMBOL(of_parse_phandle_with_args);
1627
1628/**
1629 * of_parse_phandle_with_fixed_args() - Find a node pointed by phandle in a list
1630 * @np:		pointer to a device tree node containing a list
1631 * @list_name:	property name that contains a list
1632 * @cell_count: number of argument cells following the phandle
1633 * @index:	index of a phandle to parse out
1634 * @out_args:	optional pointer to output arguments structure (will be filled)
1635 *
1636 * This function is useful to parse lists of phandles and their arguments.
1637 * Returns 0 on success and fills out_args, on error returns appropriate
1638 * errno value.
1639 *
1640 * Caller is responsible to call of_node_put() on the returned out_args->np
1641 * pointer.
1642 *
1643 * Example:
1644 *
1645 * phandle1: node1 {
1646 * }
1647 *
1648 * phandle2: node2 {
1649 * }
1650 *
1651 * node3 {
1652 *	list = <&phandle1 0 2 &phandle2 2 3>;
1653 * }
1654 *
1655 * To get a device_node of the `node2' node you may call this:
1656 * of_parse_phandle_with_fixed_args(node3, "list", 2, 1, &args);
1657 */
1658int of_parse_phandle_with_fixed_args(const struct device_node *np,
1659				const char *list_name, int cell_count,
1660				int index, struct of_phandle_args *out_args)
1661{
1662	if (index < 0)
1663		return -EINVAL;
1664	return __of_parse_phandle_with_args(np, list_name, NULL, cell_count,
1665					   index, out_args);
1666}
1667EXPORT_SYMBOL(of_parse_phandle_with_fixed_args);
1668
1669/**
1670 * of_count_phandle_with_args() - Find the number of phandles references in a property
1671 * @np:		pointer to a device tree node containing a list
1672 * @list_name:	property name that contains a list
1673 * @cells_name:	property name that specifies phandles' arguments count
1674 *
1675 * Returns the number of phandle + argument tuples within a property. It
1676 * is a typical pattern to encode a list of phandle and variable
1677 * arguments into a single property. The number of arguments is encoded
1678 * by a property in the phandle-target node. For example, a gpios
1679 * property would contain a list of GPIO specifies consisting of a
1680 * phandle and 1 or more arguments. The number of arguments are
1681 * determined by the #gpio-cells property in the node pointed to by the
1682 * phandle.
1683 */
1684int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
1685				const char *cells_name)
1686{
1687	return __of_parse_phandle_with_args(np, list_name, cells_name, 0, -1,
1688					    NULL);
1689}
1690EXPORT_SYMBOL(of_count_phandle_with_args);
1691
1692/**
1693 * __of_add_property - Add a property to a node without lock operations
1694 */
1695int __of_add_property(struct device_node *np, struct property *prop)
1696{
1697	struct property **next;
1698
1699	prop->next = NULL;
1700	next = &np->properties;
1701	while (*next) {
1702		if (strcmp(prop->name, (*next)->name) == 0)
1703			/* duplicate ! don't insert it */
1704			return -EEXIST;
1705
1706		next = &(*next)->next;
1707	}
1708	*next = prop;
1709
1710	return 0;
1711}
1712
1713/**
1714 * of_add_property - Add a property to a node
1715 */
1716int of_add_property(struct device_node *np, struct property *prop)
1717{
1718	unsigned long flags;
1719	int rc;
1720
1721	mutex_lock(&of_mutex);
1722
1723	raw_spin_lock_irqsave(&devtree_lock, flags);
1724	rc = __of_add_property(np, prop);
1725	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1726
1727	if (!rc)
1728		__of_add_property_sysfs(np, prop);
1729
1730	mutex_unlock(&of_mutex);
1731
1732	if (!rc)
1733		of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL);
1734
1735	return rc;
1736}
1737
1738int __of_remove_property(struct device_node *np, struct property *prop)
1739{
1740	struct property **next;
1741
1742	for (next = &np->properties; *next; next = &(*next)->next) {
1743		if (*next == prop)
1744			break;
1745	}
1746	if (*next == NULL)
1747		return -ENODEV;
1748
1749	/* found the node */
1750	*next = prop->next;
1751	prop->next = np->deadprops;
1752	np->deadprops = prop;
1753
1754	return 0;
1755}
1756
1757void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
1758{
1759	if (!IS_ENABLED(CONFIG_SYSFS))
1760		return;
1761
1762	/* at early boot, bail here and defer setup to of_init() */
1763	if (of_kset && of_node_is_attached(np))
1764		sysfs_remove_bin_file(&np->kobj, &prop->attr);
1765}
1766
1767/**
1768 * of_remove_property - Remove a property from a node.
1769 *
1770 * Note that we don't actually remove it, since we have given out
1771 * who-knows-how-many pointers to the data using get-property.
1772 * Instead we just move the property to the "dead properties"
1773 * list, so it won't be found any more.
1774 */
1775int of_remove_property(struct device_node *np, struct property *prop)
1776{
1777	unsigned long flags;
1778	int rc;
1779
1780	mutex_lock(&of_mutex);
1781
1782	raw_spin_lock_irqsave(&devtree_lock, flags);
1783	rc = __of_remove_property(np, prop);
1784	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1785
1786	if (!rc)
1787		__of_remove_property_sysfs(np, prop);
1788
1789	mutex_unlock(&of_mutex);
1790
1791	if (!rc)
1792		of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL);
1793
1794	return rc;
1795}
1796
1797int __of_update_property(struct device_node *np, struct property *newprop,
1798		struct property **oldpropp)
1799{
1800	struct property **next, *oldprop;
1801
1802	for (next = &np->properties; *next; next = &(*next)->next) {
1803		if (of_prop_cmp((*next)->name, newprop->name) == 0)
1804			break;
1805	}
1806	*oldpropp = oldprop = *next;
1807
1808	if (oldprop) {
1809		/* replace the node */
1810		newprop->next = oldprop->next;
1811		*next = newprop;
1812		oldprop->next = np->deadprops;
1813		np->deadprops = oldprop;
1814	} else {
1815		/* new node */
1816		newprop->next = NULL;
1817		*next = newprop;
1818	}
1819
1820	return 0;
1821}
1822
1823void __of_update_property_sysfs(struct device_node *np, struct property *newprop,
1824		struct property *oldprop)
1825{
1826	if (!IS_ENABLED(CONFIG_SYSFS))
1827		return;
1828
1829	/* At early boot, bail out and defer setup to of_init() */
1830	if (!of_kset)
1831		return;
1832
1833	if (oldprop)
1834		sysfs_remove_bin_file(&np->kobj, &oldprop->attr);
1835	__of_add_property_sysfs(np, newprop);
1836}
1837
1838/*
1839 * of_update_property - Update a property in a node, if the property does
1840 * not exist, add it.
1841 *
1842 * Note that we don't actually remove it, since we have given out
1843 * who-knows-how-many pointers to the data using get-property.
1844 * Instead we just move the property to the "dead properties" list,
1845 * and add the new property to the property list
1846 */
1847int of_update_property(struct device_node *np, struct property *newprop)
1848{
1849	struct property *oldprop;
1850	unsigned long flags;
1851	int rc;
1852
1853	if (!newprop->name)
1854		return -EINVAL;
1855
1856	mutex_lock(&of_mutex);
1857
1858	raw_spin_lock_irqsave(&devtree_lock, flags);
1859	rc = __of_update_property(np, newprop, &oldprop);
1860	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1861
1862	if (!rc)
1863		__of_update_property_sysfs(np, newprop, oldprop);
1864
1865	mutex_unlock(&of_mutex);
1866
1867	if (!rc)
1868		of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop);
1869
1870	return rc;
1871}
1872
1873static void of_alias_add(struct alias_prop *ap, struct device_node *np,
1874			 int id, const char *stem, int stem_len)
1875{
1876	ap->np = np;
1877	ap->id = id;
1878	strncpy(ap->stem, stem, stem_len);
1879	ap->stem[stem_len] = 0;
1880	list_add_tail(&ap->link, &aliases_lookup);
1881	pr_debug("adding DT alias:%s: stem=%s id=%i node=%s\n",
1882		 ap->alias, ap->stem, ap->id, of_node_full_name(np));
1883}
1884
1885/**
1886 * of_alias_scan - Scan all properties of the 'aliases' node
1887 *
1888 * The function scans all the properties of the 'aliases' node and populates
1889 * the global lookup table with the properties.  It returns the
1890 * number of alias properties found, or an error code in case of failure.
1891 *
1892 * @dt_alloc:	An allocator that provides a virtual address to memory
1893 *		for storing the resulting tree
1894 */
1895void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
1896{
1897	struct property *pp;
1898
1899	of_aliases = of_find_node_by_path("/aliases");
1900	of_chosen = of_find_node_by_path("/chosen");
1901	if (of_chosen == NULL)
1902		of_chosen = of_find_node_by_path("/chosen@0");
1903
1904	if (of_chosen) {
1905		/* linux,stdout-path and /aliases/stdout are for legacy compatibility */
1906		const char *name = of_get_property(of_chosen, "stdout-path", NULL);
1907		if (!name)
1908			name = of_get_property(of_chosen, "linux,stdout-path", NULL);
1909		if (IS_ENABLED(CONFIG_PPC) && !name)
1910			name = of_get_property(of_aliases, "stdout", NULL);
1911		if (name)
1912			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
1913	}
1914
1915	if (!of_aliases)
1916		return;
1917
1918	for_each_property_of_node(of_aliases, pp) {
1919		const char *start = pp->name;
1920		const char *end = start + strlen(start);
1921		struct device_node *np;
1922		struct alias_prop *ap;
1923		int id, len;
1924
1925		/* Skip those we do not want to proceed */
1926		if (!strcmp(pp->name, "name") ||
1927		    !strcmp(pp->name, "phandle") ||
1928		    !strcmp(pp->name, "linux,phandle"))
1929			continue;
1930
1931		np = of_find_node_by_path(pp->value);
1932		if (!np)
1933			continue;
1934
1935		/* walk the alias backwards to extract the id and work out
1936		 * the 'stem' string */
1937		while (isdigit(*(end-1)) && end > start)
1938			end--;
1939		len = end - start;
1940
1941		if (kstrtoint(end, 10, &id) < 0)
1942			continue;
1943
1944		/* Allocate an alias_prop with enough space for the stem */
1945		ap = dt_alloc(sizeof(*ap) + len + 1, 4);
1946		if (!ap)
1947			continue;
1948		memset(ap, 0, sizeof(*ap) + len + 1);
1949		ap->alias = start;
1950		of_alias_add(ap, np, id, start, len);
1951	}
1952}
1953
1954/**
1955 * of_alias_get_id - Get alias id for the given device_node
1956 * @np:		Pointer to the given device_node
1957 * @stem:	Alias stem of the given device_node
1958 *
1959 * The function travels the lookup table to get the alias id for the given
1960 * device_node and alias stem.  It returns the alias id if found.
1961 */
1962int of_alias_get_id(struct device_node *np, const char *stem)
1963{
1964	struct alias_prop *app;
1965	int id = -ENODEV;
1966
1967	mutex_lock(&of_mutex);
1968	list_for_each_entry(app, &aliases_lookup, link) {
1969		if (strcmp(app->stem, stem) != 0)
1970			continue;
1971
1972		if (np == app->np) {
1973			id = app->id;
1974			break;
1975		}
1976	}
1977	mutex_unlock(&of_mutex);
1978
1979	return id;
1980}
1981EXPORT_SYMBOL_GPL(of_alias_get_id);
1982
1983/**
1984 * of_alias_get_highest_id - Get highest alias id for the given stem
1985 * @stem:	Alias stem to be examined
1986 *
1987 * The function travels the lookup table to get the highest alias id for the
1988 * given alias stem.  It returns the alias id if found.
1989 */
1990int of_alias_get_highest_id(const char *stem)
1991{
1992	struct alias_prop *app;
1993	int id = -ENODEV;
1994
1995	mutex_lock(&of_mutex);
1996	list_for_each_entry(app, &aliases_lookup, link) {
1997		if (strcmp(app->stem, stem) != 0)
1998			continue;
1999
2000		if (app->id > id)
2001			id = app->id;
2002	}
2003	mutex_unlock(&of_mutex);
2004
2005	return id;
2006}
2007EXPORT_SYMBOL_GPL(of_alias_get_highest_id);
2008
2009const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
2010			       u32 *pu)
2011{
2012	const void *curv = cur;
2013
2014	if (!prop)
2015		return NULL;
2016
2017	if (!cur) {
2018		curv = prop->value;
2019		goto out_val;
2020	}
2021
2022	curv += sizeof(*cur);
2023	if (curv >= prop->value + prop->length)
2024		return NULL;
2025
2026out_val:
2027	*pu = be32_to_cpup(curv);
2028	return curv;
2029}
2030EXPORT_SYMBOL_GPL(of_prop_next_u32);
2031
2032const char *of_prop_next_string(struct property *prop, const char *cur)
2033{
2034	const void *curv = cur;
2035
2036	if (!prop)
2037		return NULL;
2038
2039	if (!cur)
2040		return prop->value;
2041
2042	curv += strlen(cur) + 1;
2043	if (curv >= prop->value + prop->length)
2044		return NULL;
2045
2046	return curv;
2047}
2048EXPORT_SYMBOL_GPL(of_prop_next_string);
2049
2050/**
2051 * of_console_check() - Test and setup console for DT setup
2052 * @dn - Pointer to device node
2053 * @name - Name to use for preferred console without index. ex. "ttyS"
2054 * @index - Index to use for preferred console.
2055 *
2056 * Check if the given device node matches the stdout-path property in the
2057 * /chosen node. If it does then register it as the preferred console and return
2058 * TRUE. Otherwise return FALSE.
2059 */
2060bool of_console_check(struct device_node *dn, char *name, int index)
2061{
2062	if (!dn || dn != of_stdout || console_set_on_cmdline)
2063		return false;
2064	return !add_preferred_console(name, index,
2065				      kstrdup(of_stdout_options, GFP_KERNEL));
2066}
2067EXPORT_SYMBOL_GPL(of_console_check);
2068
2069/**
2070 *	of_find_next_cache_node - Find a node's subsidiary cache
2071 *	@np:	node of type "cpu" or "cache"
2072 *
2073 *	Returns a node pointer with refcount incremented, use
2074 *	of_node_put() on it when done.  Caller should hold a reference
2075 *	to np.
2076 */
2077struct device_node *of_find_next_cache_node(const struct device_node *np)
2078{
2079	struct device_node *child;
2080	const phandle *handle;
2081
2082	handle = of_get_property(np, "l2-cache", NULL);
2083	if (!handle)
2084		handle = of_get_property(np, "next-level-cache", NULL);
2085
2086	if (handle)
2087		return of_find_node_by_phandle(be32_to_cpup(handle));
2088
2089	/* OF on pmac has nodes instead of properties named "l2-cache"
2090	 * beneath CPU nodes.
2091	 */
2092	if (!strcmp(np->type, "cpu"))
2093		for_each_child_of_node(np, child)
2094			if (!strcmp(child->type, "cache"))
2095				return child;
2096
2097	return NULL;
2098}
2099
2100/**
2101 * of_graph_parse_endpoint() - parse common endpoint node properties
2102 * @node: pointer to endpoint device_node
2103 * @endpoint: pointer to the OF endpoint data structure
2104 *
2105 * The caller should hold a reference to @node.
2106 */
2107int of_graph_parse_endpoint(const struct device_node *node,
2108			    struct of_endpoint *endpoint)
2109{
2110	struct device_node *port_node = of_get_parent(node);
2111
2112	WARN_ONCE(!port_node, "%s(): endpoint %s has no parent node\n",
2113		  __func__, node->full_name);
2114
2115	memset(endpoint, 0, sizeof(*endpoint));
2116
2117	endpoint->local_node = node;
2118	/*
2119	 * It doesn't matter whether the two calls below succeed.
2120	 * If they don't then the default value 0 is used.
2121	 */
2122	of_property_read_u32(port_node, "reg", &endpoint->port);
2123	of_property_read_u32(node, "reg", &endpoint->id);
2124
2125	of_node_put(port_node);
2126
2127	return 0;
2128}
2129EXPORT_SYMBOL(of_graph_parse_endpoint);
2130
2131/**
2132 * of_graph_get_port_by_id() - get the port matching a given id
2133 * @parent: pointer to the parent device node
2134 * @id: id of the port
2135 *
2136 * Return: A 'port' node pointer with refcount incremented. The caller
2137 * has to use of_node_put() on it when done.
2138 */
2139struct device_node *of_graph_get_port_by_id(struct device_node *parent, u32 id)
2140{
2141	struct device_node *node, *port;
2142
2143	node = of_get_child_by_name(parent, "ports");
2144	if (node)
2145		parent = node;
2146
2147	for_each_child_of_node(parent, port) {
2148		u32 port_id = 0;
2149
2150		if (of_node_cmp(port->name, "port") != 0)
2151			continue;
2152		of_property_read_u32(port, "reg", &port_id);
2153		if (id == port_id)
2154			break;
2155	}
2156
2157	of_node_put(node);
2158
2159	return port;
2160}
2161EXPORT_SYMBOL(of_graph_get_port_by_id);
2162
2163/**
2164 * of_graph_get_next_endpoint() - get next endpoint node
2165 * @parent: pointer to the parent device node
2166 * @prev: previous endpoint node, or NULL to get first
2167 *
2168 * Return: An 'endpoint' node pointer with refcount incremented. Refcount
2169 * of the passed @prev node is decremented.
2170 */
2171struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
2172					struct device_node *prev)
2173{
2174	struct device_node *endpoint;
2175	struct device_node *port;
2176
2177	if (!parent)
2178		return NULL;
2179
2180	/*
2181	 * Start by locating the port node. If no previous endpoint is specified
2182	 * search for the first port node, otherwise get the previous endpoint
2183	 * parent port node.
2184	 */
2185	if (!prev) {
2186		struct device_node *node;
2187
2188		node = of_get_child_by_name(parent, "ports");
2189		if (node)
2190			parent = node;
2191
2192		port = of_get_child_by_name(parent, "port");
2193		of_node_put(node);
2194
2195		if (!port) {
2196			pr_err("%s(): no port node found in %s\n",
2197			       __func__, parent->full_name);
2198			return NULL;
2199		}
2200	} else {
2201		port = of_get_parent(prev);
2202		if (WARN_ONCE(!port, "%s(): endpoint %s has no parent node\n",
2203			      __func__, prev->full_name))
2204			return NULL;
2205	}
2206
2207	while (1) {
2208		/*
2209		 * Now that we have a port node, get the next endpoint by
2210		 * getting the next child. If the previous endpoint is NULL this
2211		 * will return the first child.
2212		 */
2213		endpoint = of_get_next_child(port, prev);
2214		if (endpoint) {
2215			of_node_put(port);
2216			return endpoint;
2217		}
2218
2219		/* No more endpoints under this port, try the next one. */
2220		prev = NULL;
2221
2222		do {
2223			port = of_get_next_child(parent, port);
2224			if (!port)
2225				return NULL;
2226		} while (of_node_cmp(port->name, "port"));
2227	}
2228}
2229EXPORT_SYMBOL(of_graph_get_next_endpoint);
2230
2231/**
2232 * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
2233 * @parent: pointer to the parent device node
2234 * @port_reg: identifier (value of reg property) of the parent port node
2235 * @reg: identifier (value of reg property) of the endpoint node
2236 *
2237 * Return: An 'endpoint' node pointer which is identified by reg and at the same
2238 * is the child of a port node identified by port_reg. reg and port_reg are
2239 * ignored when they are -1.
2240 */
2241struct device_node *of_graph_get_endpoint_by_regs(
2242	const struct device_node *parent, int port_reg, int reg)
2243{
2244	struct of_endpoint endpoint;
2245	struct device_node *node, *prev_node = NULL;
2246
2247	while (1) {
2248		node = of_graph_get_next_endpoint(parent, prev_node);
2249		of_node_put(prev_node);
2250		if (!node)
2251			break;
2252
2253		of_graph_parse_endpoint(node, &endpoint);
2254		if (((port_reg == -1) || (endpoint.port == port_reg)) &&
2255			((reg == -1) || (endpoint.id == reg)))
2256			return node;
2257
2258		prev_node = node;
2259	}
2260
2261	return NULL;
2262}
2263EXPORT_SYMBOL(of_graph_get_endpoint_by_regs);
2264
2265/**
2266 * of_graph_get_remote_port_parent() - get remote port's parent node
2267 * @node: pointer to a local endpoint device_node
2268 *
2269 * Return: Remote device node associated with remote endpoint node linked
2270 *	   to @node. Use of_node_put() on it when done.
2271 */
2272struct device_node *of_graph_get_remote_port_parent(
2273			       const struct device_node *node)
2274{
2275	struct device_node *np;
2276	unsigned int depth;
2277
2278	/* Get remote endpoint node. */
2279	np = of_parse_phandle(node, "remote-endpoint", 0);
2280
2281	/* Walk 3 levels up only if there is 'ports' node. */
2282	for (depth = 3; depth && np; depth--) {
2283		np = of_get_next_parent(np);
2284		if (depth == 2 && of_node_cmp(np->name, "ports"))
2285			break;
2286	}
2287	return np;
2288}
2289EXPORT_SYMBOL(of_graph_get_remote_port_parent);
2290
2291/**
2292 * of_graph_get_remote_port() - get remote port node
2293 * @node: pointer to a local endpoint device_node
2294 *
2295 * Return: Remote port node associated with remote endpoint node linked
2296 *	   to @node. Use of_node_put() on it when done.
2297 */
2298struct device_node *of_graph_get_remote_port(const struct device_node *node)
2299{
2300	struct device_node *np;
2301
2302	/* Get remote endpoint node. */
2303	np = of_parse_phandle(node, "remote-endpoint", 0);
2304	if (!np)
2305		return NULL;
2306	return of_get_next_parent(np);
2307}
2308EXPORT_SYMBOL(of_graph_get_remote_port);