1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Procedures for creating, accessing and interpreting the device tree.
   4 *
   5 * Paul Mackerras	August 1996.
   6 * Copyright (C) 1996-2005 Paul Mackerras.
   7 *
   8 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
   9 *    {engebret|bergner}@us.ibm.com
  10 *
  11 *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
  12 *
  13 *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
  14 *  Grant Likely.
  15 */
  16
  17#define pr_fmt(fmt)	"OF: " fmt
  18
  19#include <linux/bitmap.h>
  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_device.h>
  26#include <linux/of_graph.h>
  27#include <linux/spinlock.h>
  28#include <linux/slab.h>
  29#include <linux/string.h>
  30#include <linux/proc_fs.h>
  31
  32#include "of_private.h"
  33
  34LIST_HEAD(aliases_lookup);
  35
  36struct device_node *of_root;
  37EXPORT_SYMBOL(of_root);
  38struct device_node *of_chosen;
 
  39struct device_node *of_aliases;
  40struct device_node *of_stdout;
  41static const char *of_stdout_options;
  42
  43struct kset *of_kset;
  44
  45/*
  46 * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
  47 * This mutex must be held whenever modifications are being made to the
  48 * device tree. The of_{attach,detach}_node() and
  49 * of_{add,remove,update}_property() helpers make sure this happens.
  50 */
  51DEFINE_MUTEX(of_mutex);
  52
  53/* use when traversing tree through the child, sibling,
  54 * or parent members of struct device_node.
  55 */
  56DEFINE_RAW_SPINLOCK(devtree_lock);
  57
  58bool of_node_name_eq(const struct device_node *np, const char *name)
  59{
  60	const char *node_name;
  61	size_t len;
  62
  63	if (!np)
  64		return false;
  65
  66	node_name = kbasename(np->full_name);
  67	len = strchrnul(node_name, '@') - node_name;
  68
  69	return (strlen(name) == len) && (strncmp(node_name, name, len) == 0);
  70}
  71EXPORT_SYMBOL(of_node_name_eq);
  72
  73bool of_node_name_prefix(const struct device_node *np, const char *prefix)
  74{
  75	if (!np)
  76		return false;
  77
  78	return strncmp(kbasename(np->full_name), prefix, strlen(prefix)) == 0;
  79}
  80EXPORT_SYMBOL(of_node_name_prefix);
  81
  82static bool __of_node_is_type(const struct device_node *np, const char *type)
  83{
  84	const char *match = __of_get_property(np, "device_type", NULL);
  85
  86	return np && match && type && !strcmp(match, type);
  87}
  88
  89int of_bus_n_addr_cells(struct device_node *np)
  90{
  91	u32 cells;
  92
  93	for (; np; np = np->parent)
  94		if (!of_property_read_u32(np, "#address-cells", &cells))
  95			return cells;
  96
  97	/* No #address-cells property for the root node */
  98	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  99}
 100
 101int of_n_addr_cells(struct device_node *np)
 102{
 103	if (np->parent)
 104		np = np->parent;
 105
 106	return of_bus_n_addr_cells(np);
 107}
 108EXPORT_SYMBOL(of_n_addr_cells);
 109
 110int of_bus_n_size_cells(struct device_node *np)
 111{
 112	u32 cells;
 113
 114	for (; np; np = np->parent)
 115		if (!of_property_read_u32(np, "#size-cells", &cells))
 116			return cells;
 117
 118	/* No #size-cells property for the root node */
 119	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
 120}
 121
 122int of_n_size_cells(struct device_node *np)
 123{
 124	if (np->parent)
 125		np = np->parent;
 126
 127	return of_bus_n_size_cells(np);
 128}
 129EXPORT_SYMBOL(of_n_size_cells);
 130
 131#ifdef CONFIG_NUMA
 132int __weak of_node_to_nid(struct device_node *np)
 133{
 134	return NUMA_NO_NODE;
 135}
 136#endif
 137
 138#define OF_PHANDLE_CACHE_BITS	7
 139#define OF_PHANDLE_CACHE_SZ	BIT(OF_PHANDLE_CACHE_BITS)
 140
 141static struct device_node *phandle_cache[OF_PHANDLE_CACHE_SZ];
 142
 143static u32 of_phandle_cache_hash(phandle handle)
 144{
 145	return hash_32(handle, OF_PHANDLE_CACHE_BITS);
 146}
 147
 148/*
 149 * Caller must hold devtree_lock.
 150 */
 151void __of_phandle_cache_inv_entry(phandle handle)
 152{
 153	u32 handle_hash;
 154	struct device_node *np;
 155
 156	if (!handle)
 157		return;
 158
 159	handle_hash = of_phandle_cache_hash(handle);
 160
 161	np = phandle_cache[handle_hash];
 162	if (np && handle == np->phandle)
 163		phandle_cache[handle_hash] = NULL;
 164}
 165
 166void __init of_core_init(void)
 167{
 168	struct device_node *np;
 169
 170
 171	/* Create the kset, and register existing nodes */
 172	mutex_lock(&of_mutex);
 173	of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
 174	if (!of_kset) {
 175		mutex_unlock(&of_mutex);
 176		pr_err("failed to register existing nodes\n");
 177		return;
 178	}
 179	for_each_of_allnodes(np) {
 180		__of_attach_node_sysfs(np);
 181		if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)])
 182			phandle_cache[of_phandle_cache_hash(np->phandle)] = np;
 183	}
 184	mutex_unlock(&of_mutex);
 185
 186	/* Symlink in /proc as required by userspace ABI */
 187	if (of_root)
 188		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
 189}
 190
 191static struct property *__of_find_property(const struct device_node *np,
 192					   const char *name, int *lenp)
 193{
 194	struct property *pp;
 195
 196	if (!np)
 197		return NULL;
 198
 199	for (pp = np->properties; pp; pp = pp->next) {
 200		if (of_prop_cmp(pp->name, name) == 0) {
 201			if (lenp)
 202				*lenp = pp->length;
 203			break;
 204		}
 205	}
 206
 207	return pp;
 208}
 209
 210struct property *of_find_property(const struct device_node *np,
 211				  const char *name,
 212				  int *lenp)
 213{
 214	struct property *pp;
 215	unsigned long flags;
 216
 217	raw_spin_lock_irqsave(&devtree_lock, flags);
 218	pp = __of_find_property(np, name, lenp);
 219	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 220
 221	return pp;
 222}
 223EXPORT_SYMBOL(of_find_property);
 224
 225struct device_node *__of_find_all_nodes(struct device_node *prev)
 226{
 227	struct device_node *np;
 228	if (!prev) {
 229		np = of_root;
 230	} else if (prev->child) {
 231		np = prev->child;
 232	} else {
 233		/* Walk back up looking for a sibling, or the end of the structure */
 234		np = prev;
 235		while (np->parent && !np->sibling)
 236			np = np->parent;
 237		np = np->sibling; /* Might be null at the end of the tree */
 238	}
 239	return np;
 240}
 241
 242/**
 243 * of_find_all_nodes - Get next node in global list
 244 * @prev:	Previous node or NULL to start iteration
 245 *		of_node_put() will be called on it
 246 *
 247 * Returns a node pointer with refcount incremented, use
 248 * of_node_put() on it when done.
 249 */
 250struct device_node *of_find_all_nodes(struct device_node *prev)
 251{
 252	struct device_node *np;
 253	unsigned long flags;
 254
 255	raw_spin_lock_irqsave(&devtree_lock, flags);
 256	np = __of_find_all_nodes(prev);
 257	of_node_get(np);
 258	of_node_put(prev);
 259	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 260	return np;
 261}
 262EXPORT_SYMBOL(of_find_all_nodes);
 263
 264/*
 265 * Find a property with a given name for a given node
 266 * and return the value.
 267 */
 268const void *__of_get_property(const struct device_node *np,
 269			      const char *name, int *lenp)
 270{
 271	struct property *pp = __of_find_property(np, name, lenp);
 272
 273	return pp ? pp->value : NULL;
 274}
 275
 276/*
 277 * Find a property with a given name for a given node
 278 * and return the value.
 279 */
 280const void *of_get_property(const struct device_node *np, const char *name,
 281			    int *lenp)
 282{
 283	struct property *pp = of_find_property(np, name, lenp);
 284
 285	return pp ? pp->value : NULL;
 286}
 287EXPORT_SYMBOL(of_get_property);
 288
 289/*
 290 * arch_match_cpu_phys_id - Match the given logical CPU and physical id
 291 *
 292 * @cpu: logical cpu index of a core/thread
 293 * @phys_id: physical identifier of a core/thread
 294 *
 295 * CPU logical to physical index mapping is architecture specific.
 296 * However this __weak function provides a default match of physical
 297 * id to logical cpu index. phys_id provided here is usually values read
 298 * from the device tree which must match the hardware internal registers.
 299 *
 300 * Returns true if the physical identifier and the logical cpu index
 301 * correspond to the same core/thread, false otherwise.
 302 */
 303bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
 304{
 305	return (u32)phys_id == cpu;
 306}
 307
 308/**
 309 * Checks if the given "prop_name" property holds the physical id of the
 310 * core/thread corresponding to the logical cpu 'cpu'. If 'thread' is not
 311 * NULL, local thread number within the core is returned in it.
 312 */
 313static bool __of_find_n_match_cpu_property(struct device_node *cpun,
 314			const char *prop_name, int cpu, unsigned int *thread)
 315{
 316	const __be32 *cell;
 317	int ac, prop_len, tid;
 318	u64 hwid;
 319
 320	ac = of_n_addr_cells(cpun);
 321	cell = of_get_property(cpun, prop_name, &prop_len);
 322	if (!cell && !ac && arch_match_cpu_phys_id(cpu, 0))
 323		return true;
 324	if (!cell || !ac)
 325		return false;
 326	prop_len /= sizeof(*cell) * ac;
 327	for (tid = 0; tid < prop_len; tid++) {
 328		hwid = of_read_number(cell, ac);
 329		if (arch_match_cpu_phys_id(cpu, hwid)) {
 330			if (thread)
 331				*thread = tid;
 332			return true;
 333		}
 334		cell += ac;
 335	}
 336	return false;
 337}
 338
 339/*
 340 * arch_find_n_match_cpu_physical_id - See if the given device node is
 341 * for the cpu corresponding to logical cpu 'cpu'.  Return true if so,
 342 * else false.  If 'thread' is non-NULL, the local thread number within the
 343 * core is returned in it.
 344 */
 345bool __weak arch_find_n_match_cpu_physical_id(struct device_node *cpun,
 346					      int cpu, unsigned int *thread)
 347{
 348	/* Check for non-standard "ibm,ppc-interrupt-server#s" property
 349	 * for thread ids on PowerPC. If it doesn't exist fallback to
 350	 * standard "reg" property.
 351	 */
 352	if (IS_ENABLED(CONFIG_PPC) &&
 353	    __of_find_n_match_cpu_property(cpun,
 354					   "ibm,ppc-interrupt-server#s",
 355					   cpu, thread))
 356		return true;
 357
 358	return __of_find_n_match_cpu_property(cpun, "reg", cpu, thread);
 359}
 360
 361/**
 362 * of_get_cpu_node - Get device node associated with the given logical CPU
 363 *
 364 * @cpu: CPU number(logical index) for which device node is required
 365 * @thread: if not NULL, local thread number within the physical core is
 366 *          returned
 367 *
 368 * The main purpose of this function is to retrieve the device node for the
 369 * given logical CPU index. It should be used to initialize the of_node in
 370 * cpu device. Once of_node in cpu device is populated, all the further
 371 * references can use that instead.
 372 *
 373 * CPU logical to physical index mapping is architecture specific and is built
 374 * before booting secondary cores. This function uses arch_match_cpu_phys_id
 375 * which can be overridden by architecture specific implementation.
 376 *
 377 * Returns a node pointer for the logical cpu with refcount incremented, use
 378 * of_node_put() on it when done. Returns NULL if not found.
 379 */
 380struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
 381{
 382	struct device_node *cpun;
 383
 384	for_each_of_cpu_node(cpun) {
 385		if (arch_find_n_match_cpu_physical_id(cpun, cpu, thread))
 386			return cpun;
 387	}
 388	return NULL;
 389}
 390EXPORT_SYMBOL(of_get_cpu_node);
 391
 392/**
 393 * of_cpu_node_to_id: Get the logical CPU number for a given device_node
 394 *
 395 * @cpu_node: Pointer to the device_node for CPU.
 396 *
 397 * Returns the logical CPU number of the given CPU device_node.
 398 * Returns -ENODEV if the CPU is not found.
 399 */
 400int of_cpu_node_to_id(struct device_node *cpu_node)
 401{
 402	int cpu;
 403	bool found = false;
 404	struct device_node *np;
 405
 406	for_each_possible_cpu(cpu) {
 407		np = of_cpu_device_node_get(cpu);
 408		found = (cpu_node == np);
 409		of_node_put(np);
 410		if (found)
 411			return cpu;
 412	}
 413
 414	return -ENODEV;
 415}
 416EXPORT_SYMBOL(of_cpu_node_to_id);
 417
 418/**
 419 * of_get_cpu_state_node - Get CPU's idle state node at the given index
 420 *
 421 * @cpu_node: The device node for the CPU
 422 * @index: The index in the list of the idle states
 423 *
 424 * Two generic methods can be used to describe a CPU's idle states, either via
 425 * a flattened description through the "cpu-idle-states" binding or via the
 426 * hierarchical layout, using the "power-domains" and the "domain-idle-states"
 427 * bindings. This function check for both and returns the idle state node for
 428 * the requested index.
 429 *
 430 * In case an idle state node is found at @index, the refcount is incremented
 431 * for it, so call of_node_put() on it when done. Returns NULL if not found.
 432 */
 433struct device_node *of_get_cpu_state_node(struct device_node *cpu_node,
 434					  int index)
 435{
 436	struct of_phandle_args args;
 437	int err;
 438
 439	err = of_parse_phandle_with_args(cpu_node, "power-domains",
 440					"#power-domain-cells", 0, &args);
 441	if (!err) {
 442		struct device_node *state_node =
 443			of_parse_phandle(args.np, "domain-idle-states", index);
 444
 445		of_node_put(args.np);
 446		if (state_node)
 447			return state_node;
 448	}
 449
 450	return of_parse_phandle(cpu_node, "cpu-idle-states", index);
 451}
 452EXPORT_SYMBOL(of_get_cpu_state_node);
 453
 454/**
 455 * __of_device_is_compatible() - Check if the node matches given constraints
 456 * @device: pointer to node
 457 * @compat: required compatible string, NULL or "" for any match
 458 * @type: required device_type value, NULL or "" for any match
 459 * @name: required node name, NULL or "" for any match
 460 *
 461 * Checks if the given @compat, @type and @name strings match the
 462 * properties of the given @device. A constraints can be skipped by
 463 * passing NULL or an empty string as the constraint.
 464 *
 465 * Returns 0 for no match, and a positive integer on match. The return
 466 * value is a relative score with larger values indicating better
 467 * matches. The score is weighted for the most specific compatible value
 468 * to get the highest score. Matching type is next, followed by matching
 469 * name. Practically speaking, this results in the following priority
 470 * order for matches:
 471 *
 472 * 1. specific compatible && type && name
 473 * 2. specific compatible && type
 474 * 3. specific compatible && name
 475 * 4. specific compatible
 476 * 5. general compatible && type && name
 477 * 6. general compatible && type
 478 * 7. general compatible && name
 479 * 8. general compatible
 480 * 9. type && name
 481 * 10. type
 482 * 11. name
 483 */
 484static int __of_device_is_compatible(const struct device_node *device,
 485				     const char *compat, const char *type, const char *name)
 486{
 487	struct property *prop;
 488	const char *cp;
 489	int index = 0, score = 0;
 490
 491	/* Compatible match has highest priority */
 492	if (compat && compat[0]) {
 493		prop = __of_find_property(device, "compatible", NULL);
 494		for (cp = of_prop_next_string(prop, NULL); cp;
 495		     cp = of_prop_next_string(prop, cp), index++) {
 496			if (of_compat_cmp(cp, compat, strlen(compat)) == 0) {
 497				score = INT_MAX/2 - (index << 2);
 498				break;
 499			}
 500		}
 501		if (!score)
 502			return 0;
 503	}
 504
 505	/* Matching type is better than matching name */
 506	if (type && type[0]) {
 507		if (!__of_node_is_type(device, type))
 508			return 0;
 509		score += 2;
 510	}
 511
 512	/* Matching name is a bit better than not */
 513	if (name && name[0]) {
 514		if (!of_node_name_eq(device, name))
 515			return 0;
 516		score++;
 517	}
 518
 519	return score;
 520}
 521
 522/** Checks if the given "compat" string matches one of the strings in
 523 * the device's "compatible" property
 524 */
 525int of_device_is_compatible(const struct device_node *device,
 526		const char *compat)
 527{
 528	unsigned long flags;
 529	int res;
 530
 531	raw_spin_lock_irqsave(&devtree_lock, flags);
 532	res = __of_device_is_compatible(device, compat, NULL, NULL);
 533	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 534	return res;
 535}
 536EXPORT_SYMBOL(of_device_is_compatible);
 537
 538/** Checks if the device is compatible with any of the entries in
 539 *  a NULL terminated array of strings. Returns the best match
 540 *  score or 0.
 541 */
 542int of_device_compatible_match(struct device_node *device,
 543			       const char *const *compat)
 544{
 545	unsigned int tmp, score = 0;
 546
 547	if (!compat)
 548		return 0;
 549
 550	while (*compat) {
 551		tmp = of_device_is_compatible(device, *compat);
 552		if (tmp > score)
 553			score = tmp;
 554		compat++;
 555	}
 556
 557	return score;
 558}
 559
 560/**
 561 * of_machine_is_compatible - Test root of device tree for a given compatible value
 562 * @compat: compatible string to look for in root node's compatible property.
 563 *
 564 * Returns a positive integer if the root node has the given value in its
 565 * compatible property.
 566 */
 567int of_machine_is_compatible(const char *compat)
 568{
 569	struct device_node *root;
 570	int rc = 0;
 571
 572	root = of_find_node_by_path("/");
 573	if (root) {
 574		rc = of_device_is_compatible(root, compat);
 575		of_node_put(root);
 576	}
 577	return rc;
 578}
 579EXPORT_SYMBOL(of_machine_is_compatible);
 580
 581/**
 582 *  __of_device_is_available - check if a device is available for use
 583 *
 584 *  @device: Node to check for availability, with locks already held
 585 *
 586 *  Returns true if the status property is absent or set to "okay" or "ok",
 587 *  false otherwise
 588 */
 589static bool __of_device_is_available(const struct device_node *device)
 590{
 591	const char *status;
 592	int statlen;
 593
 594	if (!device)
 595		return false;
 596
 597	status = __of_get_property(device, "status", &statlen);
 598	if (status == NULL)
 599		return true;
 600
 601	if (statlen > 0) {
 602		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
 603			return true;
 604	}
 605
 606	return false;
 607}
 608
 609/**
 610 *  of_device_is_available - check if a device is available for use
 611 *
 612 *  @device: Node to check for availability
 613 *
 614 *  Returns true if the status property is absent or set to "okay" or "ok",
 615 *  false otherwise
 616 */
 617bool of_device_is_available(const struct device_node *device)
 618{
 619	unsigned long flags;
 620	bool res;
 621
 622	raw_spin_lock_irqsave(&devtree_lock, flags);
 623	res = __of_device_is_available(device);
 624	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 625	return res;
 626
 627}
 628EXPORT_SYMBOL(of_device_is_available);
 629
 630/**
 631 *  of_device_is_big_endian - check if a device has BE registers
 632 *
 633 *  @device: Node to check for endianness
 634 *
 635 *  Returns true if the device has a "big-endian" property, or if the kernel
 636 *  was compiled for BE *and* the device has a "native-endian" property.
 637 *  Returns false otherwise.
 638 *
 639 *  Callers would nominally use ioread32be/iowrite32be if
 640 *  of_device_is_big_endian() == true, or readl/writel otherwise.
 641 */
 642bool of_device_is_big_endian(const struct device_node *device)
 643{
 644	if (of_property_read_bool(device, "big-endian"))
 645		return true;
 646	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
 647	    of_property_read_bool(device, "native-endian"))
 648		return true;
 649	return false;
 650}
 651EXPORT_SYMBOL(of_device_is_big_endian);
 652
 653/**
 654 *	of_get_parent - Get a node's parent if any
 655 *	@node:	Node to get parent
 656 *
 657 *	Returns a node pointer with refcount incremented, use
 658 *	of_node_put() on it when done.
 659 */
 660struct device_node *of_get_parent(const struct device_node *node)
 661{
 662	struct device_node *np;
 663	unsigned long flags;
 664
 665	if (!node)
 666		return NULL;
 667
 668	raw_spin_lock_irqsave(&devtree_lock, flags);
 669	np = of_node_get(node->parent);
 670	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 671	return np;
 672}
 673EXPORT_SYMBOL(of_get_parent);
 674
 675/**
 676 *	of_get_next_parent - Iterate to a node's parent
 677 *	@node:	Node to get parent of
 678 *
 679 *	This is like of_get_parent() except that it drops the
 680 *	refcount on the passed node, making it suitable for iterating
 681 *	through a node's parents.
 682 *
 683 *	Returns a node pointer with refcount incremented, use
 684 *	of_node_put() on it when done.
 685 */
 686struct device_node *of_get_next_parent(struct device_node *node)
 687{
 688	struct device_node *parent;
 689	unsigned long flags;
 690
 691	if (!node)
 692		return NULL;
 693
 694	raw_spin_lock_irqsave(&devtree_lock, flags);
 695	parent = of_node_get(node->parent);
 696	of_node_put(node);
 697	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 698	return parent;
 699}
 700EXPORT_SYMBOL(of_get_next_parent);
 701
 702static struct device_node *__of_get_next_child(const struct device_node *node,
 703						struct device_node *prev)
 704{
 705	struct device_node *next;
 706
 707	if (!node)
 708		return NULL;
 709
 710	next = prev ? prev->sibling : node->child;
 711	for (; next; next = next->sibling)
 712		if (of_node_get(next))
 713			break;
 714	of_node_put(prev);
 715	return next;
 716}
 717#define __for_each_child_of_node(parent, child) \
 718	for (child = __of_get_next_child(parent, NULL); child != NULL; \
 719	     child = __of_get_next_child(parent, child))
 720
 721/**
 722 *	of_get_next_child - Iterate a node childs
 723 *	@node:	parent node
 724 *	@prev:	previous child of the parent node, or NULL to get first
 725 *
 726 *	Returns a node pointer with refcount incremented, use of_node_put() on
 727 *	it when done. Returns NULL when prev is the last child. Decrements the
 728 *	refcount of prev.
 729 */
 730struct device_node *of_get_next_child(const struct device_node *node,
 731	struct device_node *prev)
 732{
 733	struct device_node *next;
 734	unsigned long flags;
 735
 736	raw_spin_lock_irqsave(&devtree_lock, flags);
 737	next = __of_get_next_child(node, prev);
 738	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 739	return next;
 740}
 741EXPORT_SYMBOL(of_get_next_child);
 742
 743/**
 744 *	of_get_next_available_child - Find the next available child node
 745 *	@node:	parent node
 746 *	@prev:	previous child of the parent node, or NULL to get first
 747 *
 748 *      This function is like of_get_next_child(), except that it
 749 *      automatically skips any disabled nodes (i.e. status = "disabled").
 750 */
 751struct device_node *of_get_next_available_child(const struct device_node *node,
 752	struct device_node *prev)
 753{
 754	struct device_node *next;
 755	unsigned long flags;
 756
 757	if (!node)
 758		return NULL;
 759
 760	raw_spin_lock_irqsave(&devtree_lock, flags);
 761	next = prev ? prev->sibling : node->child;
 762	for (; next; next = next->sibling) {
 763		if (!__of_device_is_available(next))
 764			continue;
 765		if (of_node_get(next))
 766			break;
 767	}
 768	of_node_put(prev);
 769	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 770	return next;
 771}
 772EXPORT_SYMBOL(of_get_next_available_child);
 773
 774/**
 775 *	of_get_next_cpu_node - Iterate on cpu nodes
 776 *	@prev:	previous child of the /cpus node, or NULL to get first
 777 *
 778 *	Returns a cpu node pointer with refcount incremented, use of_node_put()
 779 *	on it when done. Returns NULL when prev is the last child. Decrements
 780 *	the refcount of prev.
 781 */
 782struct device_node *of_get_next_cpu_node(struct device_node *prev)
 783{
 784	struct device_node *next = NULL;
 785	unsigned long flags;
 786	struct device_node *node;
 787
 788	if (!prev)
 789		node = of_find_node_by_path("/cpus");
 790
 791	raw_spin_lock_irqsave(&devtree_lock, flags);
 792	if (prev)
 793		next = prev->sibling;
 794	else if (node) {
 795		next = node->child;
 796		of_node_put(node);
 797	}
 798	for (; next; next = next->sibling) {
 799		if (!(of_node_name_eq(next, "cpu") ||
 800		      __of_node_is_type(next, "cpu")))
 801			continue;
 802		if (of_node_get(next))
 803			break;
 804	}
 805	of_node_put(prev);
 806	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 807	return next;
 808}
 809EXPORT_SYMBOL(of_get_next_cpu_node);
 810
 811/**
 812 * of_get_compatible_child - Find compatible child node
 813 * @parent:	parent node
 814 * @compatible:	compatible string
 815 *
 816 * Lookup child node whose compatible property contains the given compatible
 817 * string.
 818 *
 819 * Returns a node pointer with refcount incremented, use of_node_put() on it
 820 * when done; or NULL if not found.
 821 */
 822struct device_node *of_get_compatible_child(const struct device_node *parent,
 823				const char *compatible)
 824{
 825	struct device_node *child;
 826
 827	for_each_child_of_node(parent, child) {
 828		if (of_device_is_compatible(child, compatible))
 829			break;
 830	}
 831
 832	return child;
 833}
 834EXPORT_SYMBOL(of_get_compatible_child);
 835
 836/**
 837 *	of_get_child_by_name - Find the child node by name for a given parent
 838 *	@node:	parent node
 839 *	@name:	child name to look for.
 840 *
 841 *      This function looks for child node for given matching name
 842 *
 843 *	Returns a node pointer if found, with refcount incremented, use
 844 *	of_node_put() on it when done.
 845 *	Returns NULL if node is not found.
 846 */
 847struct device_node *of_get_child_by_name(const struct device_node *node,
 848				const char *name)
 849{
 850	struct device_node *child;
 851
 852	for_each_child_of_node(node, child)
 853		if (of_node_name_eq(child, name))
 854			break;
 855	return child;
 856}
 857EXPORT_SYMBOL(of_get_child_by_name);
 858
 859struct device_node *__of_find_node_by_path(struct device_node *parent,
 860						const char *path)
 861{
 862	struct device_node *child;
 863	int len;
 864
 865	len = strcspn(path, "/:");
 866	if (!len)
 867		return NULL;
 868
 869	__for_each_child_of_node(parent, child) {
 870		const char *name = kbasename(child->full_name);
 871		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
 872			return child;
 873	}
 874	return NULL;
 875}
 876
 877struct device_node *__of_find_node_by_full_path(struct device_node *node,
 878						const char *path)
 879{
 880	const char *separator = strchr(path, ':');
 881
 882	while (node && *path == '/') {
 883		struct device_node *tmp = node;
 884
 885		path++; /* Increment past '/' delimiter */
 886		node = __of_find_node_by_path(node, path);
 887		of_node_put(tmp);
 888		path = strchrnul(path, '/');
 889		if (separator && separator < path)
 890			break;
 891	}
 892	return node;
 893}
 894
 895/**
 896 *	of_find_node_opts_by_path - Find a node matching a full OF path
 897 *	@path: Either the full path to match, or if the path does not
 898 *	       start with '/', the name of a property of the /aliases
 899 *	       node (an alias).  In the case of an alias, the node
 900 *	       matching the alias' value will be returned.
 901 *	@opts: Address of a pointer into which to store the start of
 902 *	       an options string appended to the end of the path with
 903 *	       a ':' separator.
 904 *
 905 *	Valid paths:
 906 *		/foo/bar	Full path
 907 *		foo		Valid alias
 908 *		foo/bar		Valid alias + relative path
 909 *
 910 *	Returns a node pointer with refcount incremented, use
 911 *	of_node_put() on it when done.
 912 */
 913struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)
 914{
 915	struct device_node *np = NULL;
 916	struct property *pp;
 917	unsigned long flags;
 918	const char *separator = strchr(path, ':');
 919
 920	if (opts)
 921		*opts = separator ? separator + 1 : NULL;
 922
 923	if (strcmp(path, "/") == 0)
 924		return of_node_get(of_root);
 925
 926	/* The path could begin with an alias */
 927	if (*path != '/') {
 928		int len;
 929		const char *p = separator;
 930
 931		if (!p)
 932			p = strchrnul(path, '/');
 933		len = p - path;
 934
 935		/* of_aliases must not be NULL */
 936		if (!of_aliases)
 937			return NULL;
 938
 939		for_each_property_of_node(of_aliases, pp) {
 940			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
 941				np = of_find_node_by_path(pp->value);
 942				break;
 943			}
 944		}
 945		if (!np)
 946			return NULL;
 947		path = p;
 948	}
 949
 950	/* Step down the tree matching path components */
 951	raw_spin_lock_irqsave(&devtree_lock, flags);
 952	if (!np)
 953		np = of_node_get(of_root);
 954	np = __of_find_node_by_full_path(np, path);
 955	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 956	return np;
 957}
 958EXPORT_SYMBOL(of_find_node_opts_by_path);
 959
 960/**
 961 *	of_find_node_by_name - Find a node by its "name" property
 962 *	@from:	The node to start searching from or NULL; the node
 963 *		you pass will not be searched, only the next one
 964 *		will. Typically, you pass what the previous call
 965 *		returned. of_node_put() will be called on @from.
 966 *	@name:	The name string to match against
 967 *
 968 *	Returns a node pointer with refcount incremented, use
 969 *	of_node_put() on it when done.
 970 */
 971struct device_node *of_find_node_by_name(struct device_node *from,
 972	const char *name)
 973{
 974	struct device_node *np;
 975	unsigned long flags;
 976
 977	raw_spin_lock_irqsave(&devtree_lock, flags);
 978	for_each_of_allnodes_from(from, np)
 979		if (of_node_name_eq(np, name) && of_node_get(np))
 980			break;
 981	of_node_put(from);
 982	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 983	return np;
 984}
 985EXPORT_SYMBOL(of_find_node_by_name);
 986
 987/**
 988 *	of_find_node_by_type - Find a node by its "device_type" property
 989 *	@from:	The node to start searching from, or NULL to start searching
 990 *		the entire device tree. The node you pass will not be
 991 *		searched, only the next one will; typically, you pass
 992 *		what the previous call returned. of_node_put() will be
 993 *		called on from for you.
 994 *	@type:	The type string to match against
 995 *
 996 *	Returns a node pointer with refcount incremented, use
 997 *	of_node_put() on it when done.
 998 */
 999struct device_node *of_find_node_by_type(struct device_node *from,
1000	const char *type)
1001{
1002	struct device_node *np;
1003	unsigned long flags;
1004
1005	raw_spin_lock_irqsave(&devtree_lock, flags);
1006	for_each_of_allnodes_from(from, np)
1007		if (__of_node_is_type(np, type) && of_node_get(np))
1008			break;
1009	of_node_put(from);
1010	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1011	return np;
1012}
1013EXPORT_SYMBOL(of_find_node_by_type);
1014
1015/**
1016 *	of_find_compatible_node - Find a node based on type and one of the
1017 *                                tokens in its "compatible" property
1018 *	@from:		The node to start searching from or NULL, the node
1019 *			you pass will not be searched, only the next one
1020 *			will; typically, you pass what the previous call
1021 *			returned. of_node_put() will be called on it
1022 *	@type:		The type string to match "device_type" or NULL to ignore
1023 *	@compatible:	The string to match to one of the tokens in the device
1024 *			"compatible" list.
1025 *
1026 *	Returns a node pointer with refcount incremented, use
1027 *	of_node_put() on it when done.
1028 */
1029struct device_node *of_find_compatible_node(struct device_node *from,
1030	const char *type, const char *compatible)
1031{
1032	struct device_node *np;
1033	unsigned long flags;
1034
1035	raw_spin_lock_irqsave(&devtree_lock, flags);
1036	for_each_of_allnodes_from(from, np)
1037		if (__of_device_is_compatible(np, compatible, type, NULL) &&
1038		    of_node_get(np))
1039			break;
1040	of_node_put(from);
1041	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1042	return np;
1043}
1044EXPORT_SYMBOL(of_find_compatible_node);
1045
1046/**
1047 *	of_find_node_with_property - Find a node which has a property with
1048 *                                   the given name.
1049 *	@from:		The node to start searching from or NULL, the node
1050 *			you pass will not be searched, only the next one
1051 *			will; typically, you pass what the previous call
1052 *			returned. of_node_put() will be called on it
1053 *	@prop_name:	The name of the property to look for.
1054 *
1055 *	Returns a node pointer with refcount incremented, use
1056 *	of_node_put() on it when done.
1057 */
1058struct device_node *of_find_node_with_property(struct device_node *from,
1059	const char *prop_name)
1060{
1061	struct device_node *np;
1062	struct property *pp;
1063	unsigned long flags;
1064
1065	raw_spin_lock_irqsave(&devtree_lock, flags);
1066	for_each_of_allnodes_from(from, np) {
1067		for (pp = np->properties; pp; pp = pp->next) {
1068			if (of_prop_cmp(pp->name, prop_name) == 0) {
1069				of_node_get(np);
1070				goto out;
1071			}
1072		}
1073	}
1074out:
1075	of_node_put(from);
1076	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1077	return np;
1078}
1079EXPORT_SYMBOL(of_find_node_with_property);
1080
1081static
1082const struct of_device_id *__of_match_node(const struct of_device_id *matches,
1083					   const struct device_node *node)
1084{
1085	const struct of_device_id *best_match = NULL;
1086	int score, best_score = 0;
1087
1088	if (!matches)
1089		return NULL;
1090
1091	for (; matches->name[0] || matches->type[0] || matches->compatible[0]; matches++) {
1092		score = __of_device_is_compatible(node, matches->compatible,
1093						  matches->type, matches->name);
1094		if (score > best_score) {
1095			best_match = matches;
1096			best_score = score;
1097		}
1098	}
1099
1100	return best_match;
1101}
1102
1103/**
1104 * of_match_node - Tell if a device_node has a matching of_match structure
1105 *	@matches:	array of of device match structures to search in
1106 *	@node:		the of device structure to match against
1107 *
1108 *	Low level utility function used by device matching.
1109 */
1110const struct of_device_id *of_match_node(const struct of_device_id *matches,
1111					 const struct device_node *node)
1112{
1113	const struct of_device_id *match;
1114	unsigned long flags;
1115
1116	raw_spin_lock_irqsave(&devtree_lock, flags);
1117	match = __of_match_node(matches, node);
1118	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1119	return match;
1120}
1121EXPORT_SYMBOL(of_match_node);
1122
1123/**
1124 *	of_find_matching_node_and_match - Find a node based on an of_device_id
1125 *					  match table.
1126 *	@from:		The node to start searching from or NULL, the node
1127 *			you pass will not be searched, only the next one
1128 *			will; typically, you pass what the previous call
1129 *			returned. of_node_put() will be called on it
1130 *	@matches:	array of of device match structures to search in
1131 *	@match		Updated to point at the matches entry which matched
1132 *
1133 *	Returns a node pointer with refcount incremented, use
1134 *	of_node_put() on it when done.
1135 */
1136struct device_node *of_find_matching_node_and_match(struct device_node *from,
1137					const struct of_device_id *matches,
1138					const struct of_device_id **match)
1139{
1140	struct device_node *np;
1141	const struct of_device_id *m;
1142	unsigned long flags;
1143
1144	if (match)
1145		*match = NULL;
1146
1147	raw_spin_lock_irqsave(&devtree_lock, flags);
1148	for_each_of_allnodes_from(from, np) {
1149		m = __of_match_node(matches, np);
1150		if (m && of_node_get(np)) {
1151			if (match)
1152				*match = m;
1153			break;
1154		}
1155	}
1156	of_node_put(from);
1157	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1158	return np;
1159}
1160EXPORT_SYMBOL(of_find_matching_node_and_match);
1161
1162/**
1163 * of_modalias_node - Lookup appropriate modalias for a device node
1164 * @node:	pointer to a device tree node
1165 * @modalias:	Pointer to buffer that modalias value will be copied into
1166 * @len:	Length of modalias value
1167 *
1168 * Based on the value of the compatible property, this routine will attempt
1169 * to choose an appropriate modalias value for a particular device tree node.
1170 * It does this by stripping the manufacturer prefix (as delimited by a ',')
1171 * from the first entry in the compatible list property.
1172 *
1173 * This routine returns 0 on success, <0 on failure.
1174 */
1175int of_modalias_node(struct device_node *node, char *modalias, int len)
1176{
1177	const char *compatible, *p;
1178	int cplen;
1179
1180	compatible = of_get_property(node, "compatible", &cplen);
1181	if (!compatible || strlen(compatible) > cplen)
1182		return -ENODEV;
1183	p = strchr(compatible, ',');
1184	strlcpy(modalias, p ? p + 1 : compatible, len);
1185	return 0;
1186}
1187EXPORT_SYMBOL_GPL(of_modalias_node);
1188
1189/**
1190 * of_find_node_by_phandle - Find a node given a phandle
1191 * @handle:	phandle of the node to find
1192 *
1193 * Returns a node pointer with refcount incremented, use
1194 * of_node_put() on it when done.
1195 */
1196struct device_node *of_find_node_by_phandle(phandle handle)
1197{
1198	struct device_node *np = NULL;
1199	unsigned long flags;
1200	u32 handle_hash;
1201
1202	if (!handle)
1203		return NULL;
1204
1205	handle_hash = of_phandle_cache_hash(handle);
1206
1207	raw_spin_lock_irqsave(&devtree_lock, flags);
1208
1209	if (phandle_cache[handle_hash] &&
1210	    handle == phandle_cache[handle_hash]->phandle)
1211		np = phandle_cache[handle_hash];
1212
1213	if (!np) {
1214		for_each_of_allnodes(np)
1215			if (np->phandle == handle &&
1216			    !of_node_check_flag(np, OF_DETACHED)) {
1217				phandle_cache[handle_hash] = np;
1218				break;
1219			}
1220	}
1221
1222	of_node_get(np);
1223	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1224	return np;
1225}
1226EXPORT_SYMBOL(of_find_node_by_phandle);
1227
1228void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
1229{
1230	int i;
1231	printk("%s %pOF", msg, args->np);
1232	for (i = 0; i < args->args_count; i++) {
1233		const char delim = i ? ',' : ':';
1234
1235		pr_cont("%c%08x", delim, args->args[i]);
1236	}
1237	pr_cont("\n");
1238}
1239
1240int of_phandle_iterator_init(struct of_phandle_iterator *it,
1241		const struct device_node *np,
1242		const char *list_name,
1243		const char *cells_name,
1244		int cell_count)
1245{
1246	const __be32 *list;
1247	int size;
1248
1249	memset(it, 0, sizeof(*it));
1250
1251	/*
1252	 * one of cell_count or cells_name must be provided to determine the
1253	 * argument length.
1254	 */
1255	if (cell_count < 0 && !cells_name)
1256		return -EINVAL;
1257
1258	list = of_get_property(np, list_name, &size);
1259	if (!list)
1260		return -ENOENT;
1261
1262	it->cells_name = cells_name;
1263	it->cell_count = cell_count;
1264	it->parent = np;
1265	it->list_end = list + size / sizeof(*list);
1266	it->phandle_end = list;
1267	it->cur = list;
1268
1269	return 0;
1270}
1271EXPORT_SYMBOL_GPL(of_phandle_iterator_init);
1272
1273int of_phandle_iterator_next(struct of_phandle_iterator *it)
1274{
1275	uint32_t count = 0;
1276
1277	if (it->node) {
1278		of_node_put(it->node);
1279		it->node = NULL;
1280	}
1281
1282	if (!it->cur || it->phandle_end >= it->list_end)
1283		return -ENOENT;
1284
1285	it->cur = it->phandle_end;
1286
1287	/* If phandle is 0, then it is an empty entry with no arguments. */
1288	it->phandle = be32_to_cpup(it->cur++);
1289
1290	if (it->phandle) {
1291
1292		/*
1293		 * Find the provider node and parse the #*-cells property to
1294		 * determine the argument length.
1295		 */
1296		it->node = of_find_node_by_phandle(it->phandle);
1297
1298		if (it->cells_name) {
1299			if (!it->node) {
1300				pr_err("%pOF: could not find phandle\n",
1301				       it->parent);
1302				goto err;
1303			}
1304
1305			if (of_property_read_u32(it->node, it->cells_name,
1306						 &count)) {
1307				/*
1308				 * If both cell_count and cells_name is given,
1309				 * fall back to cell_count in absence
1310				 * of the cells_name property
1311				 */
1312				if (it->cell_count >= 0) {
1313					count = it->cell_count;
1314				} else {
1315					pr_err("%pOF: could not get %s for %pOF\n",
1316					       it->parent,
1317					       it->cells_name,
1318					       it->node);
1319					goto err;
1320				}
1321			}
1322		} else {
1323			count = it->cell_count;
1324		}
1325
1326		/*
1327		 * Make sure that the arguments actually fit in the remaining
1328		 * property data length
1329		 */
1330		if (it->cur + count > it->list_end) {
1331			pr_err("%pOF: %s = %d found %d\n",
1332			       it->parent, it->cells_name,
1333			       count, it->cell_count);
1334			goto err;
1335		}
1336	}
1337
1338	it->phandle_end = it->cur + count;
1339	it->cur_count = count;
1340
1341	return 0;
1342
1343err:
1344	if (it->node) {
1345		of_node_put(it->node);
1346		it->node = NULL;
1347	}
1348
1349	return -EINVAL;
1350}
1351EXPORT_SYMBOL_GPL(of_phandle_iterator_next);
1352
1353int of_phandle_iterator_args(struct of_phandle_iterator *it,
1354			     uint32_t *args,
1355			     int size)
1356{
1357	int i, count;
1358
1359	count = it->cur_count;
1360
1361	if (WARN_ON(size < count))
1362		count = size;
1363
1364	for (i = 0; i < count; i++)
1365		args[i] = be32_to_cpup(it->cur++);
1366
1367	return count;
1368}
1369
1370static int __of_parse_phandle_with_args(const struct device_node *np,
1371					const char *list_name,
1372					const char *cells_name,
1373					int cell_count, int index,
1374					struct of_phandle_args *out_args)
1375{
1376	struct of_phandle_iterator it;
1377	int rc, cur_index = 0;
1378
1379	/* Loop over the phandles until all the requested entry is found */
1380	of_for_each_phandle(&it, rc, np, list_name, cells_name, cell_count) {
1381		/*
1382		 * All of the error cases bail out of the loop, so at
1383		 * this point, the parsing is successful. If the requested
1384		 * index matches, then fill the out_args structure and return,
1385		 * or return -ENOENT for an empty entry.
1386		 */
1387		rc = -ENOENT;
1388		if (cur_index == index) {
1389			if (!it.phandle)
1390				goto err;
1391
1392			if (out_args) {
1393				int c;
1394
1395				c = of_phandle_iterator_args(&it,
1396							     out_args->args,
1397							     MAX_PHANDLE_ARGS);
1398				out_args->np = it.node;
1399				out_args->args_count = c;
1400			} else {
1401				of_node_put(it.node);
1402			}
1403
1404			/* Found it! return success */
1405			return 0;
1406		}
1407
1408		cur_index++;
1409	}
1410
1411	/*
1412	 * Unlock node before returning result; will be one of:
1413	 * -ENOENT : index is for empty phandle
1414	 * -EINVAL : parsing error on data
1415	 */
1416
1417 err:
1418	of_node_put(it.node);
1419	return rc;
1420}
1421
1422/**
1423 * of_parse_phandle - Resolve a phandle property to a device_node pointer
1424 * @np: Pointer to device node holding phandle property
1425 * @phandle_name: Name of property holding a phandle value
1426 * @index: For properties holding a table of phandles, this is the index into
1427 *         the table
1428 *
1429 * Returns the device_node pointer with refcount incremented.  Use
1430 * of_node_put() on it when done.
1431 */
1432struct device_node *of_parse_phandle(const struct device_node *np,
1433				     const char *phandle_name, int index)
1434{
1435	struct of_phandle_args args;
1436
1437	if (index < 0)
1438		return NULL;
1439
1440	if (__of_parse_phandle_with_args(np, phandle_name, NULL, 0,
1441					 index, &args))
1442		return NULL;
1443
1444	return args.np;
1445}
1446EXPORT_SYMBOL(of_parse_phandle);
1447
1448/**
1449 * of_parse_phandle_with_args() - Find a node pointed by phandle in a list
1450 * @np:		pointer to a device tree node containing a list
1451 * @list_name:	property name that contains a list
1452 * @cells_name:	property name that specifies phandles' arguments count
1453 * @index:	index of a phandle to parse out
1454 * @out_args:	optional pointer to output arguments structure (will be filled)
1455 *
1456 * This function is useful to parse lists of phandles and their arguments.
1457 * Returns 0 on success and fills out_args, on error returns appropriate
1458 * errno value.
1459 *
1460 * Caller is responsible to call of_node_put() on the returned out_args->np
1461 * pointer.
1462 *
1463 * Example:
1464 *
1465 * phandle1: node1 {
1466 *	#list-cells = <2>;
1467 * }
1468 *
1469 * phandle2: node2 {
1470 *	#list-cells = <1>;
1471 * }
1472 *
1473 * node3 {
1474 *	list = <&phandle1 1 2 &phandle2 3>;
1475 * }
1476 *
1477 * To get a device_node of the `node2' node you may call this:
1478 * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args);
1479 */
1480int of_parse_phandle_with_args(const struct device_node *np, const char *list_name,
1481				const char *cells_name, int index,
1482				struct of_phandle_args *out_args)
1483{
1484	int cell_count = -1;
1485
1486	if (index < 0)
1487		return -EINVAL;
1488
1489	/* If cells_name is NULL we assume a cell count of 0 */
1490	if (!cells_name)
1491		cell_count = 0;
1492
1493	return __of_parse_phandle_with_args(np, list_name, cells_name,
1494					    cell_count, index, out_args);
1495}
1496EXPORT_SYMBOL(of_parse_phandle_with_args);
1497
1498/**
1499 * of_parse_phandle_with_args_map() - Find a node pointed by phandle in a list and remap it
1500 * @np:		pointer to a device tree node containing a list
1501 * @list_name:	property name that contains a list
1502 * @stem_name:	stem of property names that specify phandles' arguments count
1503 * @index:	index of a phandle to parse out
1504 * @out_args:	optional pointer to output arguments structure (will be filled)
1505 *
1506 * This function is useful to parse lists of phandles and their arguments.
1507 * Returns 0 on success and fills out_args, on error returns appropriate errno
1508 * value. The difference between this function and of_parse_phandle_with_args()
1509 * is that this API remaps a phandle if the node the phandle points to has
1510 * a <@stem_name>-map property.
1511 *
1512 * Caller is responsible to call of_node_put() on the returned out_args->np
1513 * pointer.
1514 *
1515 * Example:
1516 *
1517 * phandle1: node1 {
1518 *	#list-cells = <2>;
1519 * }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1520 *
1521 * phandle2: node2 {
1522 *	#list-cells = <1>;
1523 * }
1524 *
1525 * phandle3: node3 {
1526 * 	#list-cells = <1>;
1527 * 	list-map = <0 &phandle2 3>,
1528 * 		   <1 &phandle2 2>,
1529 * 		   <2 &phandle1 5 1>;
1530 *	list-map-mask = <0x3>;
1531 * };
1532 *
1533 * node4 {
1534 *	list = <&phandle1 1 2 &phandle3 0>;
1535 * }
1536 *
1537 * To get a device_node of the `node2' node you may call this:
1538 * of_parse_phandle_with_args(node4, "list", "list", 1, &args);
1539 */
1540int of_parse_phandle_with_args_map(const struct device_node *np,
1541				   const char *list_name,
1542				   const char *stem_name,
1543				   int index, struct of_phandle_args *out_args)
1544{
1545	char *cells_name, *map_name = NULL, *mask_name = NULL;
1546	char *pass_name = NULL;
1547	struct device_node *cur, *new = NULL;
1548	const __be32 *map, *mask, *pass;
1549	static const __be32 dummy_mask[] = { [0 ... MAX_PHANDLE_ARGS] = ~0 };
1550	static const __be32 dummy_pass[] = { [0 ... MAX_PHANDLE_ARGS] = 0 };
1551	__be32 initial_match_array[MAX_PHANDLE_ARGS];
1552	const __be32 *match_array = initial_match_array;
1553	int i, ret, map_len, match;
1554	u32 list_size, new_size;
1555
1556	if (index < 0)
1557		return -EINVAL;
1558
1559	cells_name = kasprintf(GFP_KERNEL, "#%s-cells", stem_name);
1560	if (!cells_name)
1561		return -ENOMEM;
1562
1563	ret = -ENOMEM;
1564	map_name = kasprintf(GFP_KERNEL, "%s-map", stem_name);
1565	if (!map_name)
1566		goto free;
1567
1568	mask_name = kasprintf(GFP_KERNEL, "%s-map-mask", stem_name);
1569	if (!mask_name)
1570		goto free;
1571
1572	pass_name = kasprintf(GFP_KERNEL, "%s-map-pass-thru", stem_name);
1573	if (!pass_name)
1574		goto free;
1575
1576	ret = __of_parse_phandle_with_args(np, list_name, cells_name, -1, index,
1577					   out_args);
1578	if (ret)
1579		goto free;
1580
1581	/* Get the #<list>-cells property */
1582	cur = out_args->np;
1583	ret = of_property_read_u32(cur, cells_name, &list_size);
1584	if (ret < 0)
1585		goto put;
1586
1587	/* Precalculate the match array - this simplifies match loop */
1588	for (i = 0; i < list_size; i++)
1589		initial_match_array[i] = cpu_to_be32(out_args->args[i]);
1590
1591	ret = -EINVAL;
1592	while (cur) {
1593		/* Get the <list>-map property */
1594		map = of_get_property(cur, map_name, &map_len);
1595		if (!map) {
1596			ret = 0;
1597			goto free;
1598		}
1599		map_len /= sizeof(u32);
1600
1601		/* Get the <list>-map-mask property (optional) */
1602		mask = of_get_property(cur, mask_name, NULL);
1603		if (!mask)
1604			mask = dummy_mask;
1605		/* Iterate through <list>-map property */
1606		match = 0;
1607		while (map_len > (list_size + 1) && !match) {
1608			/* Compare specifiers */
1609			match = 1;
1610			for (i = 0; i < list_size; i++, map_len--)
1611				match &= !((match_array[i] ^ *map++) & mask[i]);
1612
1613			of_node_put(new);
1614			new = of_find_node_by_phandle(be32_to_cpup(map));
1615			map++;
1616			map_len--;
1617
1618			/* Check if not found */
1619			if (!new)
1620				goto put;
1621
1622			if (!of_device_is_available(new))
1623				match = 0;
1624
1625			ret = of_property_read_u32(new, cells_name, &new_size);
1626			if (ret)
1627				goto put;
1628
1629			/* Check for malformed properties */
1630			if (WARN_ON(new_size > MAX_PHANDLE_ARGS))
1631				goto put;
1632			if (map_len < new_size)
1633				goto put;
1634
1635			/* Move forward by new node's #<list>-cells amount */
1636			map += new_size;
1637			map_len -= new_size;
1638		}
1639		if (!match)
1640			goto put;
1641
1642		/* Get the <list>-map-pass-thru property (optional) */
1643		pass = of_get_property(cur, pass_name, NULL);
1644		if (!pass)
1645			pass = dummy_pass;
1646
1647		/*
1648		 * Successfully parsed a <list>-map translation; copy new
1649		 * specifier into the out_args structure, keeping the
1650		 * bits specified in <list>-map-pass-thru.
1651		 */
1652		match_array = map - new_size;
1653		for (i = 0; i < new_size; i++) {
1654			__be32 val = *(map - new_size + i);
1655
1656			if (i < list_size) {
1657				val &= ~pass[i];
1658				val |= cpu_to_be32(out_args->args[i]) & pass[i];
1659			}
1660
1661			out_args->args[i] = be32_to_cpu(val);
1662		}
1663		out_args->args_count = list_size = new_size;
1664		/* Iterate again with new provider */
1665		out_args->np = new;
1666		of_node_put(cur);
1667		cur = new;
1668	}
1669put:
1670	of_node_put(cur);
1671	of_node_put(new);
1672free:
1673	kfree(mask_name);
1674	kfree(map_name);
1675	kfree(cells_name);
1676	kfree(pass_name);
1677
1678	return ret;
1679}
1680EXPORT_SYMBOL(of_parse_phandle_with_args_map);
1681
1682/**
1683 * of_parse_phandle_with_fixed_args() - Find a node pointed by phandle in a list
1684 * @np:		pointer to a device tree node containing a list
1685 * @list_name:	property name that contains a list
1686 * @cell_count: number of argument cells following the phandle
1687 * @index:	index of a phandle to parse out
1688 * @out_args:	optional pointer to output arguments structure (will be filled)
1689 *
1690 * This function is useful to parse lists of phandles and their arguments.
1691 * Returns 0 on success and fills out_args, on error returns appropriate
1692 * errno value.
1693 *
1694 * Caller is responsible to call of_node_put() on the returned out_args->np
1695 * pointer.
1696 *
1697 * Example:
1698 *
1699 * phandle1: node1 {
1700 * }
1701 *
1702 * phandle2: node2 {
1703 * }
1704 *
1705 * node3 {
1706 *	list = <&phandle1 0 2 &phandle2 2 3>;
1707 * }
1708 *
1709 * To get a device_node of the `node2' node you may call this:
1710 * of_parse_phandle_with_fixed_args(node3, "list", 2, 1, &args);
1711 */
1712int of_parse_phandle_with_fixed_args(const struct device_node *np,
1713				const char *list_name, int cell_count,
1714				int index, struct of_phandle_args *out_args)
1715{
1716	if (index < 0)
1717		return -EINVAL;
1718	return __of_parse_phandle_with_args(np, list_name, NULL, cell_count,
1719					   index, out_args);
1720}
1721EXPORT_SYMBOL(of_parse_phandle_with_fixed_args);
1722
1723/**
1724 * of_count_phandle_with_args() - Find the number of phandles references in a property
1725 * @np:		pointer to a device tree node containing a list
1726 * @list_name:	property name that contains a list
1727 * @cells_name:	property name that specifies phandles' arguments count
1728 *
1729 * Returns the number of phandle + argument tuples within a property. It
1730 * is a typical pattern to encode a list of phandle and variable
1731 * arguments into a single property. The number of arguments is encoded
1732 * by a property in the phandle-target node. For example, a gpios
1733 * property would contain a list of GPIO specifies consisting of a
1734 * phandle and 1 or more arguments. The number of arguments are
1735 * determined by the #gpio-cells property in the node pointed to by the
1736 * phandle.
1737 */
1738int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
1739				const char *cells_name)
1740{
1741	struct of_phandle_iterator it;
1742	int rc, cur_index = 0;
1743
1744	/*
1745	 * If cells_name is NULL we assume a cell count of 0. This makes
1746	 * counting the phandles trivial as each 32bit word in the list is a
1747	 * phandle and no arguments are to consider. So we don't iterate through
1748	 * the list but just use the length to determine the phandle count.
1749	 */
1750	if (!cells_name) {
1751		const __be32 *list;
1752		int size;
1753
1754		list = of_get_property(np, list_name, &size);
1755		if (!list)
1756			return -ENOENT;
1757
1758		return size / sizeof(*list);
1759	}
1760
1761	rc = of_phandle_iterator_init(&it, np, list_name, cells_name, -1);
1762	if (rc)
1763		return rc;
1764
1765	while ((rc = of_phandle_iterator_next(&it)) == 0)
1766		cur_index += 1;
1767
1768	if (rc != -ENOENT)
1769		return rc;
1770
1771	return cur_index;
1772}
1773EXPORT_SYMBOL(of_count_phandle_with_args);
1774
1775/**
1776 * __of_add_property - Add a property to a node without lock operations
 
 
1777 */
1778int __of_add_property(struct device_node *np, struct property *prop)
1779{
1780	struct property **next;
1781
1782	prop->next = NULL;
1783	next = &np->properties;
1784	while (*next) {
1785		if (strcmp(prop->name, (*next)->name) == 0)
1786			/* duplicate ! don't insert it */
1787			return -EEXIST;
1788
1789		next = &(*next)->next;
1790	}
1791	*next = prop;
1792
1793	return 0;
1794}
1795
1796/**
1797 * of_add_property - Add a property to a node
 
 
1798 */
1799int of_add_property(struct device_node *np, struct property *prop)
1800{
1801	unsigned long flags;
1802	int rc;
1803
1804	mutex_lock(&of_mutex);
1805
1806	raw_spin_lock_irqsave(&devtree_lock, flags);
1807	rc = __of_add_property(np, prop);
1808	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1809
1810	if (!rc)
1811		__of_add_property_sysfs(np, prop);
1812
1813	mutex_unlock(&of_mutex);
1814
1815	if (!rc)
1816		of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL);
1817
1818	return rc;
1819}
1820
1821int __of_remove_property(struct device_node *np, struct property *prop)
1822{
1823	struct property **next;
1824
1825	for (next = &np->properties; *next; next = &(*next)->next) {
1826		if (*next == prop)
1827			break;
1828	}
1829	if (*next == NULL)
1830		return -ENODEV;
1831
1832	/* found the node */
1833	*next = prop->next;
1834	prop->next = np->deadprops;
1835	np->deadprops = prop;
1836
1837	return 0;
1838}
1839
1840/**
1841 * of_remove_property - Remove a property from a node.
 
 
1842 *
1843 * Note that we don't actually remove it, since we have given out
1844 * who-knows-how-many pointers to the data using get-property.
1845 * Instead we just move the property to the "dead properties"
1846 * list, so it won't be found any more.
1847 */
1848int of_remove_property(struct device_node *np, struct property *prop)
1849{
1850	unsigned long flags;
1851	int rc;
1852
1853	if (!prop)
1854		return -ENODEV;
1855
1856	mutex_lock(&of_mutex);
1857
1858	raw_spin_lock_irqsave(&devtree_lock, flags);
1859	rc = __of_remove_property(np, prop);
1860	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1861
1862	if (!rc)
1863		__of_remove_property_sysfs(np, prop);
1864
1865	mutex_unlock(&of_mutex);
1866
1867	if (!rc)
1868		of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL);
1869
1870	return rc;
1871}
 
1872
1873int __of_update_property(struct device_node *np, struct property *newprop,
1874		struct property **oldpropp)
1875{
1876	struct property **next, *oldprop;
1877
1878	for (next = &np->properties; *next; next = &(*next)->next) {
1879		if (of_prop_cmp((*next)->name, newprop->name) == 0)
1880			break;
1881	}
1882	*oldpropp = oldprop = *next;
1883
1884	if (oldprop) {
1885		/* replace the node */
1886		newprop->next = oldprop->next;
1887		*next = newprop;
1888		oldprop->next = np->deadprops;
1889		np->deadprops = oldprop;
1890	} else {
1891		/* new node */
1892		newprop->next = NULL;
1893		*next = newprop;
1894	}
1895
1896	return 0;
1897}
1898
1899/*
1900 * of_update_property - Update a property in a node, if the property does
1901 * not exist, add it.
1902 *
1903 * Note that we don't actually remove it, since we have given out
1904 * who-knows-how-many pointers to the data using get-property.
1905 * Instead we just move the property to the "dead properties" list,
1906 * and add the new property to the property list
1907 */
1908int of_update_property(struct device_node *np, struct property *newprop)
1909{
1910	struct property *oldprop;
1911	unsigned long flags;
1912	int rc;
1913
1914	if (!newprop->name)
1915		return -EINVAL;
1916
1917	mutex_lock(&of_mutex);
1918
1919	raw_spin_lock_irqsave(&devtree_lock, flags);
1920	rc = __of_update_property(np, newprop, &oldprop);
1921	raw_spin_unlock_irqrestore(&devtree_lock, flags);
1922
1923	if (!rc)
1924		__of_update_property_sysfs(np, newprop, oldprop);
1925
1926	mutex_unlock(&of_mutex);
1927
1928	if (!rc)
1929		of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop);
1930
1931	return rc;
1932}
1933
1934static void of_alias_add(struct alias_prop *ap, struct device_node *np,
1935			 int id, const char *stem, int stem_len)
1936{
1937	ap->np = np;
1938	ap->id = id;
1939	strncpy(ap->stem, stem, stem_len);
1940	ap->stem[stem_len] = 0;
1941	list_add_tail(&ap->link, &aliases_lookup);
1942	pr_debug("adding DT alias:%s: stem=%s id=%i node=%pOF\n",
1943		 ap->alias, ap->stem, ap->id, np);
1944}
1945
1946/**
1947 * of_alias_scan - Scan all properties of the 'aliases' node
 
 
1948 *
1949 * The function scans all the properties of the 'aliases' node and populates
1950 * the global lookup table with the properties.  It returns the
1951 * number of alias properties found, or an error code in case of failure.
1952 *
1953 * @dt_alloc:	An allocator that provides a virtual address to memory
1954 *		for storing the resulting tree
1955 */
1956void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
1957{
1958	struct property *pp;
1959
1960	of_aliases = of_find_node_by_path("/aliases");
1961	of_chosen = of_find_node_by_path("/chosen");
1962	if (of_chosen == NULL)
1963		of_chosen = of_find_node_by_path("/chosen@0");
1964
1965	if (of_chosen) {
1966		/* linux,stdout-path and /aliases/stdout are for legacy compatibility */
1967		const char *name = NULL;
1968
1969		if (of_property_read_string(of_chosen, "stdout-path", &name))
1970			of_property_read_string(of_chosen, "linux,stdout-path",
1971						&name);
1972		if (IS_ENABLED(CONFIG_PPC) && !name)
1973			of_property_read_string(of_aliases, "stdout", &name);
1974		if (name)
1975			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
1976	}
1977
1978	if (!of_aliases)
1979		return;
1980
1981	for_each_property_of_node(of_aliases, pp) {
1982		const char *start = pp->name;
1983		const char *end = start + strlen(start);
1984		struct device_node *np;
1985		struct alias_prop *ap;
1986		int id, len;
1987
1988		/* Skip those we do not want to proceed */
1989		if (!strcmp(pp->name, "name") ||
1990		    !strcmp(pp->name, "phandle") ||
1991		    !strcmp(pp->name, "linux,phandle"))
1992			continue;
1993
1994		np = of_find_node_by_path(pp->value);
1995		if (!np)
1996			continue;
1997
1998		/* walk the alias backwards to extract the id and work out
1999		 * the 'stem' string */
2000		while (isdigit(*(end-1)) && end > start)
2001			end--;
2002		len = end - start;
2003
2004		if (kstrtoint(end, 10, &id) < 0)
2005			continue;
2006
2007		/* Allocate an alias_prop with enough space for the stem */
2008		ap = dt_alloc(sizeof(*ap) + len + 1, __alignof__(*ap));
2009		if (!ap)
2010			continue;
2011		memset(ap, 0, sizeof(*ap) + len + 1);
2012		ap->alias = start;
2013		of_alias_add(ap, np, id, start, len);
2014	}
2015}
2016
2017/**
2018 * of_alias_get_id - Get alias id for the given device_node
2019 * @np:		Pointer to the given device_node
2020 * @stem:	Alias stem of the given device_node
2021 *
2022 * The function travels the lookup table to get the alias id for the given
2023 * device_node and alias stem.  It returns the alias id if found.
 
 
2024 */
2025int of_alias_get_id(struct device_node *np, const char *stem)
2026{
2027	struct alias_prop *app;
2028	int id = -ENODEV;
2029
2030	mutex_lock(&of_mutex);
2031	list_for_each_entry(app, &aliases_lookup, link) {
2032		if (strcmp(app->stem, stem) != 0)
2033			continue;
2034
2035		if (np == app->np) {
2036			id = app->id;
2037			break;
2038		}
2039	}
2040	mutex_unlock(&of_mutex);
2041
2042	return id;
2043}
2044EXPORT_SYMBOL_GPL(of_alias_get_id);
2045
2046/**
2047 * of_alias_get_alias_list - Get alias list for the given device driver
2048 * @matches:	Array of OF device match structures to search in
2049 * @stem:	Alias stem of the given device_node
2050 * @bitmap:	Bitmap field pointer
2051 * @nbits:	Maximum number of alias IDs which can be recorded in bitmap
2052 *
2053 * The function travels the lookup table to record alias ids for the given
2054 * device match structures and alias stem.
2055 *
2056 * Return:	0 or -ENOSYS when !CONFIG_OF or
2057 *		-EOVERFLOW if alias ID is greater then allocated nbits
2058 */
2059int of_alias_get_alias_list(const struct of_device_id *matches,
2060			     const char *stem, unsigned long *bitmap,
2061			     unsigned int nbits)
2062{
2063	struct alias_prop *app;
2064	int ret = 0;
2065
2066	/* Zero bitmap field to make sure that all the time it is clean */
2067	bitmap_zero(bitmap, nbits);
2068
2069	mutex_lock(&of_mutex);
2070	pr_debug("%s: Looking for stem: %s\n", __func__, stem);
2071	list_for_each_entry(app, &aliases_lookup, link) {
2072		pr_debug("%s: stem: %s, id: %d\n",
2073			 __func__, app->stem, app->id);
2074
2075		if (strcmp(app->stem, stem) != 0) {
2076			pr_debug("%s: stem comparison didn't pass %s\n",
2077				 __func__, app->stem);
2078			continue;
2079		}
2080
2081		if (of_match_node(matches, app->np)) {
2082			pr_debug("%s: Allocated ID %d\n", __func__, app->id);
2083
2084			if (app->id >= nbits) {
2085				pr_warn("%s: ID %d >= than bitmap field %d\n",
2086					__func__, app->id, nbits);
2087				ret = -EOVERFLOW;
2088			} else {
2089				set_bit(app->id, bitmap);
2090			}
2091		}
2092	}
2093	mutex_unlock(&of_mutex);
2094
2095	return ret;
2096}
2097EXPORT_SYMBOL_GPL(of_alias_get_alias_list);
2098
2099/**
2100 * of_alias_get_highest_id - Get highest alias id for the given stem
2101 * @stem:	Alias stem to be examined
2102 *
2103 * The function travels the lookup table to get the highest alias id for the
2104 * given alias stem.  It returns the alias id if found.
2105 */
2106int of_alias_get_highest_id(const char *stem)
2107{
2108	struct alias_prop *app;
2109	int id = -ENODEV;
2110
2111	mutex_lock(&of_mutex);
2112	list_for_each_entry(app, &aliases_lookup, link) {
2113		if (strcmp(app->stem, stem) != 0)
2114			continue;
2115
2116		if (app->id > id)
2117			id = app->id;
2118	}
2119	mutex_unlock(&of_mutex);
2120
2121	return id;
2122}
2123EXPORT_SYMBOL_GPL(of_alias_get_highest_id);
2124
2125/**
2126 * of_console_check() - Test and setup console for DT setup
2127 * @dn - Pointer to device node
2128 * @name - Name to use for preferred console without index. ex. "ttyS"
2129 * @index - Index to use for preferred console.
2130 *
2131 * Check if the given device node matches the stdout-path property in the
2132 * /chosen node. If it does then register it as the preferred console and return
2133 * TRUE. Otherwise return FALSE.
 
2134 */
2135bool of_console_check(struct device_node *dn, char *name, int index)
2136{
2137	if (!dn || dn != of_stdout || console_set_on_cmdline)
2138		return false;
2139
2140	/*
2141	 * XXX: cast `options' to char pointer to suppress complication
2142	 * warnings: printk, UART and console drivers expect char pointer.
2143	 */
2144	return !add_preferred_console(name, index, (char *)of_stdout_options);
2145}
2146EXPORT_SYMBOL_GPL(of_console_check);
2147
2148/**
2149 *	of_find_next_cache_node - Find a node's subsidiary cache
2150 *	@np:	node of type "cpu" or "cache"
2151 *
2152 *	Returns a node pointer with refcount incremented, use
2153 *	of_node_put() on it when done.  Caller should hold a reference
2154 *	to np.
2155 */
2156struct device_node *of_find_next_cache_node(const struct device_node *np)
2157{
2158	struct device_node *child, *cache_node;
2159
2160	cache_node = of_parse_phandle(np, "l2-cache", 0);
2161	if (!cache_node)
2162		cache_node = of_parse_phandle(np, "next-level-cache", 0);
2163
2164	if (cache_node)
2165		return cache_node;
2166
2167	/* OF on pmac has nodes instead of properties named "l2-cache"
2168	 * beneath CPU nodes.
2169	 */
2170	if (IS_ENABLED(CONFIG_PPC_PMAC) && of_node_is_type(np, "cpu"))
2171		for_each_child_of_node(np, child)
2172			if (of_node_is_type(child, "cache"))
2173				return child;
2174
2175	return NULL;
2176}
2177
2178/**
2179 * of_find_last_cache_level - Find the level at which the last cache is
2180 * 		present for the given logical cpu
2181 *
2182 * @cpu: cpu number(logical index) for which the last cache level is needed
2183 *
2184 * Returns the the level at which the last cache is present. It is exactly
2185 * same as  the total number of cache levels for the given logical cpu.
2186 */
2187int of_find_last_cache_level(unsigned int cpu)
2188{
2189	u32 cache_level = 0;
2190	struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
2191
2192	while (np) {
2193		prev = np;
2194		of_node_put(np);
2195		np = of_find_next_cache_node(np);
2196	}
2197
2198	of_property_read_u32(prev, "cache-level", &cache_level);
2199
2200	return cache_level;
2201}
2202
2203/**
2204 * of_map_id - Translate an ID through a downstream mapping.
2205 * @np: root complex device node.
2206 * @id: device ID to map.
2207 * @map_name: property name of the map to use.
2208 * @map_mask_name: optional property name of the mask to use.
2209 * @target: optional pointer to a target device node.
2210 * @id_out: optional pointer to receive the translated ID.
2211 *
2212 * Given a device ID, look up the appropriate implementation-defined
2213 * platform ID and/or the target device which receives transactions on that
2214 * ID, as per the "iommu-map" and "msi-map" bindings. Either of @target or
2215 * @id_out may be NULL if only the other is required. If @target points to
2216 * a non-NULL device node pointer, only entries targeting that node will be
2217 * matched; if it points to a NULL value, it will receive the device node of
2218 * the first matching target phandle, with a reference held.
2219 *
2220 * Return: 0 on success or a standard error code on failure.
2221 */
2222int of_map_id(struct device_node *np, u32 id,
2223	       const char *map_name, const char *map_mask_name,
2224	       struct device_node **target, u32 *id_out)
2225{
2226	u32 map_mask, masked_id;
2227	int map_len;
2228	const __be32 *map = NULL;
2229
2230	if (!np || !map_name || (!target && !id_out))
2231		return -EINVAL;
2232
2233	map = of_get_property(np, map_name, &map_len);
2234	if (!map) {
2235		if (target)
2236			return -ENODEV;
2237		/* Otherwise, no map implies no translation */
2238		*id_out = id;
2239		return 0;
2240	}
2241
2242	if (!map_len || map_len % (4 * sizeof(*map))) {
2243		pr_err("%pOF: Error: Bad %s length: %d\n", np,
2244			map_name, map_len);
2245		return -EINVAL;
2246	}
2247
2248	/* The default is to select all bits. */
2249	map_mask = 0xffffffff;
2250
2251	/*
2252	 * Can be overridden by "{iommu,msi}-map-mask" property.
2253	 * If of_property_read_u32() fails, the default is used.
2254	 */
2255	if (map_mask_name)
2256		of_property_read_u32(np, map_mask_name, &map_mask);
2257
2258	masked_id = map_mask & id;
2259	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
2260		struct device_node *phandle_node;
2261		u32 id_base = be32_to_cpup(map + 0);
2262		u32 phandle = be32_to_cpup(map + 1);
2263		u32 out_base = be32_to_cpup(map + 2);
2264		u32 id_len = be32_to_cpup(map + 3);
2265
2266		if (id_base & ~map_mask) {
2267			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
2268				np, map_name, map_name,
2269				map_mask, id_base);
2270			return -EFAULT;
2271		}
2272
2273		if (masked_id < id_base || masked_id >= id_base + id_len)
2274			continue;
2275
2276		phandle_node = of_find_node_by_phandle(phandle);
2277		if (!phandle_node)
2278			return -ENODEV;
2279
2280		if (target) {
2281			if (*target)
2282				of_node_put(phandle_node);
2283			else
2284				*target = phandle_node;
2285
2286			if (*target != phandle_node)
2287				continue;
2288		}
2289
2290		if (id_out)
2291			*id_out = masked_id - id_base + out_base;
2292
2293		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
2294			np, map_name, map_mask, id_base, out_base,
2295			id_len, id, masked_id - id_base + out_base);
2296		return 0;
2297	}
2298
2299	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
2300		id, target && *target ? *target : NULL);
2301
2302	/* Bypasses translation */
2303	if (id_out)
2304		*id_out = id;
2305	return 0;
2306}
2307EXPORT_SYMBOL_GPL(of_map_id);