개념 설명 전체 · v6.18.37 / drivers/of/base.c

    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 [email protected]
   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/cleanup.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 
   34 LIST_HEAD(aliases_lookup);
   35 
   36 struct device_node *of_root;
   37 EXPORT_SYMBOL(of_root);
   38 struct device_node *of_chosen;
   39 EXPORT_SYMBOL(of_chosen);
   40 struct device_node *of_aliases;
   41 struct device_node *of_stdout;
   42 static const char *of_stdout_options;
   43 
   44 struct kset *of_kset;
   45 
   46 /*
   47  * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
   48  * This mutex must be held whenever modifications are being made to the
   49  * device tree. The of_{attach,detach}_node() and
   50  * of_{add,remove,update}_property() helpers make sure this happens.
   51  */
   52 DEFINE_MUTEX(of_mutex);
   53 
   54 /* use when traversing tree through the child, sibling,
   55  * or parent members of struct device_node.
   56  */
   57 DEFINE_RAW_SPINLOCK(devtree_lock);
   58 
   59 bool of_node_name_eq(const struct device_node *np, const char *name)
   60 {
   61 	const char *node_name;
   62 	size_t len;
   63 
   64 	if (!np)
   65 		return false;
   66 
   67 	node_name = kbasename(np->full_name);
   68 	len = strchrnul(node_name, '@') - node_name;
   69 
   70 	return (strlen(name) == len) && (strncmp(node_name, name, len) == 0);
   71 }
   72 EXPORT_SYMBOL(of_node_name_eq);
   73 
   74 bool of_node_name_prefix(const struct device_node *np, const char *prefix)
   75 {
   76 	if (!np)
   77 		return false;
   78 
   79 	return strncmp(kbasename(np->full_name), prefix, strlen(prefix)) == 0;
   80 }
   81 EXPORT_SYMBOL(of_node_name_prefix);
   82 
   83 static bool __of_node_is_type(const struct device_node *np, const char *type)
   84 {
   85 	const char *match = __of_get_property(np, "device_type", NULL);
   86 
   87 	return np && match && type && !strcmp(match, type);
   88 }
   89 
   90 #define EXCLUDED_DEFAULT_CELLS_PLATFORMS ( \
   91 	IS_ENABLED(CONFIG_SPARC) || \
   92 	of_find_compatible_node(NULL, NULL, "coreboot") \
   93 )
   94 
   95 int of_bus_n_addr_cells(struct device_node *np)
   96 {
   97 	u32 cells;
   98 
   99 	for (; np; np = np->parent) {
  100 		if (!of_property_read_u32(np, "#address-cells", &cells))
  101 			return cells;
  102 		/*
  103 		 * Default root value and walking parent nodes for "#address-cells"
  104 		 * is deprecated. Any platforms which hit this warning should
  105 		 * be added to the excluded list.
  106 		 */
  107 		WARN_ONCE(!EXCLUDED_DEFAULT_CELLS_PLATFORMS,
  108 			  "Missing '#address-cells' in %pOF\n", np);
  109 	}
  110 	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  111 }
  112 
  113 int of_n_addr_cells(struct device_node *np)
  114 {
  115 	if (np->parent)
  116 		np = np->parent;
  117 
  118 	return of_bus_n_addr_cells(np);
  119 }
  120 EXPORT_SYMBOL(of_n_addr_cells);
  121 
  122 int of_bus_n_size_cells(struct device_node *np)
  123 {
  124 	u32 cells;
  125 
  126 	for (; np; np = np->parent) {
  127 		if (!of_property_read_u32(np, "#size-cells", &cells))
  128 			return cells;
  129 		/*
  130 		 * Default root value and walking parent nodes for "#size-cells"
  131 		 * is deprecated. Any platforms which hit this warning should
  132 		 * be added to the excluded list.
  133 		 */
  134 		WARN_ONCE(!EXCLUDED_DEFAULT_CELLS_PLATFORMS,
  135 			  "Missing '#size-cells' in %pOF\n", np);
  136 	}
  137 	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  138 }
  139 
  140 int of_n_size_cells(struct device_node *np)
  141 {
  142 	if (np->parent)
  143 		np = np->parent;
  144 
  145 	return of_bus_n_size_cells(np);
  146 }
  147 EXPORT_SYMBOL(of_n_size_cells);
  148 
  149 #ifdef CONFIG_NUMA
  150 int __weak of_node_to_nid(struct device_node *np)
  151 {
  152 	return NUMA_NO_NODE;
  153 }
  154 #endif
  155 
  156 #define OF_PHANDLE_CACHE_BITS	7
  157 #define OF_PHANDLE_CACHE_SZ	BIT(OF_PHANDLE_CACHE_BITS)
  158 
  159 static struct device_node *phandle_cache[OF_PHANDLE_CACHE_SZ];
  160 
  161 static u32 of_phandle_cache_hash(phandle handle)
  162 {
  163 	return hash_32(handle, OF_PHANDLE_CACHE_BITS);
  164 }
  165 
  166 /*
  167  * Caller must hold devtree_lock.
  168  */
  169 void __of_phandle_cache_inv_entry(phandle handle)
  170 {
  171 	u32 handle_hash;
  172 	struct device_node *np;
  173 
  174 	if (!handle)
  175 		return;
  176 
  177 	handle_hash = of_phandle_cache_hash(handle);
  178 
  179 	np = phandle_cache[handle_hash];
  180 	if (np && handle == np->phandle)
  181 		phandle_cache[handle_hash] = NULL;
  182 }
  183 
  184 void __init of_core_init(void)
  185 {
  186 	struct device_node *np;
  187 
  188 	of_platform_register_reconfig_notifier();
  189 
  190 	/* Create the kset, and register existing nodes */
  191 	mutex_lock(&of_mutex);
  192 	of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
  193 	if (!of_kset) {
  194 		mutex_unlock(&of_mutex);
  195 		pr_err("failed to register existing nodes\n");
  196 		return;
  197 	}
  198 	for_each_of_allnodes(np) {
  199 		__of_attach_node_sysfs(np);
  200 		if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)])
  201 			phandle_cache[of_phandle_cache_hash(np->phandle)] = np;
  202 	}
  203 	mutex_unlock(&of_mutex);
  204 
  205 	/* Symlink in /proc as required by userspace ABI */
  206 	if (of_root)
  207 		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
  208 }
  209 
  210 static struct property *__of_find_property(const struct device_node *np,
  211 					   const char *name, int *lenp)
  212 {
  213 	struct property *pp;
  214 
  215 	if (!np)
  216 		return NULL;
  217 
  218 	for (pp = np->properties; pp; pp = pp->next) {
  219 		if (of_prop_cmp(pp->name, name) == 0) {
  220 			if (lenp)
  221 				*lenp = pp->length;
  222 			break;
  223 		}
  224 	}
  225 
  226 	return pp;
  227 }
  228 
  229 struct property *of_find_property(const struct device_node *np,
  230 				  const char *name,
  231 				  int *lenp)
  232 {
  233 	struct property *pp;
  234 	unsigned long flags;
  235 
  236 	raw_spin_lock_irqsave(&devtree_lock, flags);
  237 	pp = __of_find_property(np, name, lenp);
  238 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  239 
  240 	return pp;
  241 }
  242 EXPORT_SYMBOL(of_find_property);
  243 
  244 struct device_node *__of_find_all_nodes(struct device_node *prev)
  245 {
  246 	struct device_node *np;
  247 	if (!prev) {
  248 		np = of_root;
  249 	} else if (prev->child) {
  250 		np = prev->child;
  251 	} else {
  252 		/* Walk back up looking for a sibling, or the end of the structure */
  253 		np = prev;
  254 		while (np->parent && !np->sibling)
  255 			np = np->parent;
  256 		np = np->sibling; /* Might be null at the end of the tree */
  257 	}
  258 	return np;
  259 }
  260 
  261 /**
  262  * of_find_all_nodes - Get next node in global list
  263  * @prev:	Previous node or NULL to start iteration
  264  *		of_node_put() will be called on it
  265  *
  266  * Return: A node pointer with refcount incremented, use
  267  * of_node_put() on it when done.
  268  */
  269 struct device_node *of_find_all_nodes(struct device_node *prev)
  270 {
  271 	struct device_node *np;
  272 	unsigned long flags;
  273 
  274 	raw_spin_lock_irqsave(&devtree_lock, flags);
  275 	np = __of_find_all_nodes(prev);
  276 	of_node_get(np);
  277 	of_node_put(prev);
  278 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  279 	return np;
  280 }
  281 EXPORT_SYMBOL(of_find_all_nodes);
  282 
  283 /*
  284  * Find a property with a given name for a given node
  285  * and return the value.
  286  */
  287 const void *__of_get_property(const struct device_node *np,
  288 			      const char *name, int *lenp)
  289 {
  290 	const struct property *pp = __of_find_property(np, name, lenp);
  291 
  292 	return pp ? pp->value : NULL;
  293 }
  294 
  295 /*
  296  * Find a property with a given name for a given node
  297  * and return the value.
  298  */
  299 const void *of_get_property(const struct device_node *np, const char *name,
  300 			    int *lenp)
  301 {
  302 	const struct property *pp = of_find_property(np, name, lenp);
  303 
  304 	return pp ? pp->value : NULL;
  305 }
  306 EXPORT_SYMBOL(of_get_property);
  307 
  308 /**
  309  * __of_device_is_compatible() - Check if the node matches given constraints
  310  * @device: pointer to node
  311  * @compat: required compatible string, NULL or "" for any match
  312  * @type: required device_type value, NULL or "" for any match
  313  * @name: required node name, NULL or "" for any match
  314  *
  315  * Checks if the given @compat, @type and @name strings match the
  316  * properties of the given @device. A constraints can be skipped by
  317  * passing NULL or an empty string as the constraint.
  318  *
  319  * Returns 0 for no match, and a positive integer on match. The return
  320  * value is a relative score with larger values indicating better
  321  * matches. The score is weighted for the most specific compatible value
  322  * to get the highest score. Matching type is next, followed by matching
  323  * name. Practically speaking, this results in the following priority
  324  * order for matches:
  325  *
  326  * 1. specific compatible && type && name
  327  * 2. specific compatible && type
  328  * 3. specific compatible && name
  329  * 4. specific compatible
  330  * 5. general compatible && type && name
  331  * 6. general compatible && type
  332  * 7. general compatible && name
  333  * 8. general compatible
  334  * 9. type && name
  335  * 10. type
  336  * 11. name
  337  */
  338 static int __of_device_is_compatible(const struct device_node *device,
  339 				     const char *compat, const char *type, const char *name)
  340 {
  341 	const struct property *prop;
  342 	const char *cp;
  343 	int index = 0, score = 0;
  344 
  345 	/* Compatible match has highest priority */
  346 	if (compat && compat[0]) {
  347 		prop = __of_find_property(device, "compatible", NULL);
  348 		for (cp = of_prop_next_string(prop, NULL); cp;
  349 		     cp = of_prop_next_string(prop, cp), index++) {
  350 			if (of_compat_cmp(cp, compat, strlen(compat)) == 0) {
  351 				score = INT_MAX/2 - (index << 2);
  352 				break;
  353 			}
  354 		}
  355 		if (!score)
  356 			return 0;
  357 	}
  358 
  359 	/* Matching type is better than matching name */
  360 	if (type && type[0]) {
  361 		if (!__of_node_is_type(device, type))
  362 			return 0;
  363 		score += 2;
  364 	}
  365 
  366 	/* Matching name is a bit better than not */
  367 	if (name && name[0]) {
  368 		if (!of_node_name_eq(device, name))
  369 			return 0;
  370 		score++;
  371 	}
  372 
  373 	return score;
  374 }
  375 
  376 /** Checks if the given "compat" string matches one of the strings in
  377  * the device's "compatible" property
  378  */
  379 int of_device_is_compatible(const struct device_node *device,
  380 		const char *compat)
  381 {
  382 	unsigned long flags;
  383 	int res;
  384 
  385 	raw_spin_lock_irqsave(&devtree_lock, flags);
  386 	res = __of_device_is_compatible(device, compat, NULL, NULL);
  387 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  388 	return res;
  389 }
  390 EXPORT_SYMBOL(of_device_is_compatible);
  391 
  392 /** Checks if the device is compatible with any of the entries in
  393  *  a NULL terminated array of strings. Returns the best match
  394  *  score or 0.
  395  */
  396 int of_device_compatible_match(const struct device_node *device,
  397 			       const char *const *compat)
  398 {
  399 	unsigned int tmp, score = 0;
  400 
  401 	if (!compat)
  402 		return 0;
  403 
  404 	while (*compat) {
  405 		tmp = of_device_is_compatible(device, *compat);
  406 		if (tmp > score)
  407 			score = tmp;
  408 		compat++;
  409 	}
  410 
  411 	return score;
  412 }
  413 EXPORT_SYMBOL_GPL(of_device_compatible_match);
  414 
  415 /**
  416  * of_machine_compatible_match - Test root of device tree against a compatible array
  417  * @compats: NULL terminated array of compatible strings to look for in root node's compatible property.
  418  *
  419  * Returns true if the root node has any of the given compatible values in its
  420  * compatible property.
  421  */
  422 bool of_machine_compatible_match(const char *const *compats)
  423 {
  424 	struct device_node *root;
  425 	int rc = 0;
  426 
  427 	root = of_find_node_by_path("/");
  428 	if (root) {
  429 		rc = of_device_compatible_match(root, compats);
  430 		of_node_put(root);
  431 	}
  432 
  433 	return rc != 0;
  434 }
  435 EXPORT_SYMBOL(of_machine_compatible_match);
  436 
  437 static bool __of_device_is_status(const struct device_node *device,
  438 				  const char * const*strings)
  439 {
  440 	const char *status;
  441 	int statlen;
  442 
  443 	if (!device)
  444 		return false;
  445 
  446 	status = __of_get_property(device, "status", &statlen);
  447 	if (status == NULL)
  448 		return false;
  449 
  450 	if (statlen > 0) {
  451 		while (*strings) {
  452 			unsigned int len = strlen(*strings);
  453 
  454 			if ((*strings)[len - 1] == '-') {
  455 				if (!strncmp(status, *strings, len))
  456 					return true;
  457 			} else {
  458 				if (!strcmp(status, *strings))
  459 					return true;
  460 			}
  461 			strings++;
  462 		}
  463 	}
  464 
  465 	return false;
  466 }
  467 
  468 /**
  469  *  __of_device_is_available - check if a device is available for use
  470  *
  471  *  @device: Node to check for availability, with locks already held
  472  *
  473  *  Return: True if the status property is absent or set to "okay" or "ok",
  474  *  false otherwise
  475  */
  476 static bool __of_device_is_available(const struct device_node *device)
  477 {
  478 	static const char * const ok[] = {"okay", "ok", NULL};
  479 
  480 	if (!device)
  481 		return false;
  482 
  483 	return !__of_get_property(device, "status", NULL) ||
  484 		__of_device_is_status(device, ok);
  485 }
  486 
  487 /**
  488  *  __of_device_is_reserved - check if a device is reserved
  489  *
  490  *  @device: Node to check for availability, with locks already held
  491  *
  492  *  Return: True if the status property is set to "reserved", false otherwise
  493  */
  494 static bool __of_device_is_reserved(const struct device_node *device)
  495 {
  496 	static const char * const reserved[] = {"reserved", NULL};
  497 
  498 	return __of_device_is_status(device, reserved);
  499 }
  500 
  501 /**
  502  *  of_device_is_available - check if a device is available for use
  503  *
  504  *  @device: Node to check for availability
  505  *
  506  *  Return: True if the status property is absent or set to "okay" or "ok",
  507  *  false otherwise
  508  */
  509 bool of_device_is_available(const struct device_node *device)
  510 {
  511 	unsigned long flags;
  512 	bool res;
  513 
  514 	raw_spin_lock_irqsave(&devtree_lock, flags);
  515 	res = __of_device_is_available(device);
  516 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  517 	return res;
  518 
  519 }
  520 EXPORT_SYMBOL(of_device_is_available);
  521 
  522 /**
  523  *  __of_device_is_fail - check if a device has status "fail" or "fail-..."
  524  *
  525  *  @device: Node to check status for, with locks already held
  526  *
  527  *  Return: True if the status property is set to "fail" or "fail-..." (for any
  528  *  error code suffix), false otherwise
  529  */
  530 static bool __of_device_is_fail(const struct device_node *device)
  531 {
  532 	static const char * const fail[] = {"fail", "fail-", NULL};
  533 
  534 	return __of_device_is_status(device, fail);
  535 }
  536 
  537 /**
  538  *  of_device_is_big_endian - check if a device has BE registers
  539  *
  540  *  @device: Node to check for endianness
  541  *
  542  *  Return: True if the device has a "big-endian" property, or if the kernel
  543  *  was compiled for BE *and* the device has a "native-endian" property.
  544  *  Returns false otherwise.
  545  *
  546  *  Callers would nominally use ioread32be/iowrite32be if
  547  *  of_device_is_big_endian() == true, or readl/writel otherwise.
  548  */
  549 bool of_device_is_big_endian(const struct device_node *device)
  550 {
  551 	if (of_property_read_bool(device, "big-endian"))
  552 		return true;
  553 	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
  554 	    of_property_read_bool(device, "native-endian"))
  555 		return true;
  556 	return false;
  557 }
  558 EXPORT_SYMBOL(of_device_is_big_endian);
  559 
  560 /**
  561  * of_get_parent - Get a node's parent if any
  562  * @node:	Node to get parent
  563  *
  564  * Return: A node pointer with refcount incremented, use
  565  * of_node_put() on it when done.
  566  */
  567 struct device_node *of_get_parent(const struct device_node *node)
  568 {
  569 	struct device_node *np;
  570 	unsigned long flags;
  571 
  572 	if (!node)
  573 		return NULL;
  574 
  575 	raw_spin_lock_irqsave(&devtree_lock, flags);
  576 	np = of_node_get(node->parent);
  577 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  578 	return np;
  579 }
  580 EXPORT_SYMBOL(of_get_parent);
  581 
  582 /**
  583  * of_get_next_parent - Iterate to a node's parent
  584  * @node:	Node to get parent of
  585  *
  586  * This is like of_get_parent() except that it drops the
  587  * refcount on the passed node, making it suitable for iterating
  588  * through a node's parents.
  589  *
  590  * Return: A node pointer with refcount incremented, use
  591  * of_node_put() on it when done.
  592  */
  593 struct device_node *of_get_next_parent(struct device_node *node)
  594 {
  595 	struct device_node *parent;
  596 	unsigned long flags;
  597 
  598 	if (!node)
  599 		return NULL;
  600 
  601 	raw_spin_lock_irqsave(&devtree_lock, flags);
  602 	parent = of_node_get(node->parent);
  603 	of_node_put(node);
  604 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  605 	return parent;
  606 }
  607 EXPORT_SYMBOL(of_get_next_parent);
  608 
  609 static struct device_node *__of_get_next_child(const struct device_node *node,
  610 						struct device_node *prev)
  611 {
  612 	struct device_node *next;
  613 
  614 	if (!node)
  615 		return NULL;
  616 
  617 	next = prev ? prev->sibling : node->child;
  618 	of_node_get(next);
  619 	of_node_put(prev);
  620 	return next;
  621 }
  622 #define __for_each_child_of_node(parent, child) \
  623 	for (child = __of_get_next_child(parent, NULL); child != NULL; \
  624 	     child = __of_get_next_child(parent, child))
  625 
  626 /**
  627  * of_get_next_child - Iterate a node childs
  628  * @node:	parent node
  629  * @prev:	previous child of the parent node, or NULL to get first
  630  *
  631  * Return: A node pointer with refcount incremented, use of_node_put() on
  632  * it when done. Returns NULL when prev is the last child. Decrements the
  633  * refcount of prev.
  634  */
  635 struct device_node *of_get_next_child(const struct device_node *node,
  636 	struct device_node *prev)
  637 {
  638 	struct device_node *next;
  639 	unsigned long flags;
  640 
  641 	raw_spin_lock_irqsave(&devtree_lock, flags);
  642 	next = __of_get_next_child(node, prev);
  643 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  644 	return next;
  645 }
  646 EXPORT_SYMBOL(of_get_next_child);
  647 
  648 /**
  649  * of_get_next_child_with_prefix - Find the next child node with prefix
  650  * @node:	parent node
  651  * @prev:	previous child of the parent node, or NULL to get first
  652  * @prefix:	prefix that the node name should have
  653  *
  654  * This function is like of_get_next_child(), except that it automatically
  655  * skips any nodes whose name doesn't have the given prefix.
  656  *
  657  * Return: A node pointer with refcount incremented, use
  658  * of_node_put() on it when done.
  659  */
  660 struct device_node *of_get_next_child_with_prefix(const struct device_node *node,
  661 						  struct device_node *prev,
  662 						  const char *prefix)
  663 {
  664 	struct device_node *next;
  665 	unsigned long flags;
  666 
  667 	if (!node)
  668 		return NULL;
  669 
  670 	raw_spin_lock_irqsave(&devtree_lock, flags);
  671 	next = prev ? prev->sibling : node->child;
  672 	for (; next; next = next->sibling) {
  673 		if (!of_node_name_prefix(next, prefix))
  674 			continue;
  675 		if (of_node_get(next))
  676 			break;
  677 	}
  678 	of_node_put(prev);
  679 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  680 	return next;
  681 }
  682 EXPORT_SYMBOL(of_get_next_child_with_prefix);
  683 
  684 static struct device_node *of_get_next_status_child(const struct device_node *node,
  685 						    struct device_node *prev,
  686 						    bool (*checker)(const struct device_node *))
  687 {
  688 	struct device_node *next;
  689 	unsigned long flags;
  690 
  691 	if (!node)
  692 		return NULL;
  693 
  694 	raw_spin_lock_irqsave(&devtree_lock, flags);
  695 	next = prev ? prev->sibling : node->child;
  696 	for (; next; next = next->sibling) {
  697 		if (!checker(next))
  698 			continue;
  699 		if (of_node_get(next))
  700 			break;
  701 	}
  702 	of_node_put(prev);
  703 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  704 	return next;
  705 }
  706 
  707 /**
  708  * of_get_next_available_child - Find the next available child node
  709  * @node:	parent node
  710  * @prev:	previous child of the parent node, or NULL to get first
  711  *
  712  * This function is like of_get_next_child(), except that it
  713  * automatically skips any disabled nodes (i.e. status = "disabled").
  714  */
  715 struct device_node *of_get_next_available_child(const struct device_node *node,
  716 	struct device_node *prev)
  717 {
  718 	return of_get_next_status_child(node, prev, __of_device_is_available);
  719 }
  720 EXPORT_SYMBOL(of_get_next_available_child);
  721 
  722 /**
  723  * of_get_next_reserved_child - Find the next reserved child node
  724  * @node:	parent node
  725  * @prev:	previous child of the parent node, or NULL to get first
  726  *
  727  * This function is like of_get_next_child(), except that it
  728  * automatically skips any disabled nodes (i.e. status = "disabled").
  729  */
  730 struct device_node *of_get_next_reserved_child(const struct device_node *node,
  731 						struct device_node *prev)
  732 {
  733 	return of_get_next_status_child(node, prev, __of_device_is_reserved);
  734 }
  735 EXPORT_SYMBOL(of_get_next_reserved_child);
  736 
  737 /**
  738  * of_get_next_cpu_node - Iterate on cpu nodes
  739  * @prev:	previous child of the /cpus node, or NULL to get first
  740  *
  741  * Unusable CPUs (those with the status property set to "fail" or "fail-...")
  742  * will be skipped.
  743  *
  744  * Return: A cpu node pointer with refcount incremented, use of_node_put()
  745  * on it when done. Returns NULL when prev is the last child. Decrements
  746  * the refcount of prev.
  747  */
  748 struct device_node *of_get_next_cpu_node(struct device_node *prev)
  749 {
  750 	struct device_node *next = NULL;
  751 	unsigned long flags;
  752 	struct device_node *node;
  753 
  754 	if (!prev)
  755 		node = of_find_node_by_path("/cpus");
  756 
  757 	raw_spin_lock_irqsave(&devtree_lock, flags);
  758 	if (prev)
  759 		next = prev->sibling;
  760 	else if (node) {
  761 		next = node->child;
  762 		of_node_put(node);
  763 	}
  764 	for (; next; next = next->sibling) {
  765 		if (__of_device_is_fail(next))
  766 			continue;
  767 		if (!(of_node_name_eq(next, "cpu") ||
  768 		      __of_node_is_type(next, "cpu")))
  769 			continue;
  770 		if (of_node_get(next))
  771 			break;
  772 	}
  773 	of_node_put(prev);
  774 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  775 	return next;
  776 }
  777 EXPORT_SYMBOL(of_get_next_cpu_node);
  778 
  779 /**
  780  * of_get_compatible_child - Find compatible child node
  781  * @parent:	parent node
  782  * @compatible:	compatible string
  783  *
  784  * Lookup child node whose compatible property contains the given compatible
  785  * string.
  786  *
  787  * Return: a node pointer with refcount incremented, use of_node_put() on it
  788  * when done; or NULL if not found.
  789  */
  790 struct device_node *of_get_compatible_child(const struct device_node *parent,
  791 				const char *compatible)
  792 {
  793 	struct device_node *child;
  794 
  795 	for_each_child_of_node(parent, child) {
  796 		if (of_device_is_compatible(child, compatible))
  797 			break;
  798 	}
  799 
  800 	return child;
  801 }
  802 EXPORT_SYMBOL(of_get_compatible_child);
  803 
  804 /**
  805  * of_get_child_by_name - Find the child node by name for a given parent
  806  * @node:	parent node
  807  * @name:	child name to look for.
  808  *
  809  * This function looks for child node for given matching name
  810  *
  811  * Return: A node pointer if found, with refcount incremented, use
  812  * of_node_put() on it when done.
  813  * Returns NULL if node is not found.
  814  */
  815 struct device_node *of_get_child_by_name(const struct device_node *node,
  816 				const char *name)
  817 {
  818 	struct device_node *child;
  819 
  820 	for_each_child_of_node(node, child)
  821 		if (of_node_name_eq(child, name))
  822 			break;
  823 	return child;
  824 }
  825 EXPORT_SYMBOL(of_get_child_by_name);
  826 
  827 /**
  828  * of_get_available_child_by_name - Find the available child node by name for a given parent
  829  * @node:	parent node
  830  * @name:	child name to look for.
  831  *
  832  * This function looks for child node for given matching name and checks the
  833  * device's availability for use.
  834  *
  835  * Return: A node pointer if found, with refcount incremented, use
  836  * of_node_put() on it when done.
  837  * Returns NULL if node is not found.
  838  */
  839 struct device_node *of_get_available_child_by_name(const struct device_node *node,
  840 						   const char *name)
  841 {
  842 	struct device_node *child;
  843 
  844 	child = of_get_child_by_name(node, name);
  845 	if (child && !of_device_is_available(child)) {
  846 		of_node_put(child);
  847 		return NULL;
  848 	}
  849 
  850 	return child;
  851 }
  852 EXPORT_SYMBOL(of_get_available_child_by_name);
  853 
  854 struct device_node *__of_find_node_by_path(const struct device_node *parent,
  855 						const char *path)
  856 {
  857 	struct device_node *child;
  858 	int len;
  859 
  860 	len = strcspn(path, "/:");
  861 	if (!len)
  862 		return NULL;
  863 
  864 	__for_each_child_of_node(parent, child) {
  865 		const char *name = kbasename(child->full_name);
  866 		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
  867 			return child;
  868 	}
  869 	return NULL;
  870 }
  871 
  872 struct device_node *__of_find_node_by_full_path(struct device_node *node,
  873 						const char *path)
  874 {
  875 	const char *separator = strchr(path, ':');
  876 
  877 	while (node && *path == '/') {
  878 		struct device_node *tmp = node;
  879 
  880 		path++; /* Increment past '/' delimiter */
  881 		node = __of_find_node_by_path(node, path);
  882 		of_node_put(tmp);
  883 		path = strchrnul(path, '/');
  884 		if (separator && separator < path)
  885 			break;
  886 	}
  887 	return node;
  888 }
  889 
  890 /**
  891  * of_find_node_opts_by_path - Find a node matching a full OF path
  892  * @path: Either the full path to match, or if the path does not
  893  *       start with '/', the name of a property of the /aliases
  894  *       node (an alias).  In the case of an alias, the node
  895  *       matching the alias' value will be returned.
  896  * @opts: Address of a pointer into which to store the start of
  897  *       an options string appended to the end of the path with
  898  *       a ':' separator.
  899  *
  900  * Valid paths:
  901  *  * /foo/bar	Full path
  902  *  * foo	Valid alias
  903  *  * foo/bar	Valid alias + relative path
  904  *
  905  * Return: A node pointer with refcount incremented, use
  906  * of_node_put() on it when done.
  907  */
  908 struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)
  909 {
  910 	struct device_node *np = NULL;
  911 	const struct property *pp;
  912 	unsigned long flags;
  913 	const char *separator = strchr(path, ':');
  914 
  915 	if (opts)
  916 		*opts = separator ? separator + 1 : NULL;
  917 
  918 	if (strcmp(path, "/") == 0)
  919 		return of_node_get(of_root);
  920 
  921 	/* The path could begin with an alias */
  922 	if (*path != '/') {
  923 		int len;
  924 		const char *p = strchrnul(path, '/');
  925 
  926 		if (separator && separator < p)
  927 			p = separator;
  928 		len = p - path;
  929 
  930 		/* of_aliases must not be NULL */
  931 		if (!of_aliases)
  932 			return NULL;
  933 
  934 		for_each_property_of_node(of_aliases, pp) {
  935 			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
  936 				np = of_find_node_by_path(pp->value);
  937 				break;
  938 			}
  939 		}
  940 		if (!np)
  941 			return NULL;
  942 		path = p;
  943 	}
  944 
  945 	/* Step down the tree matching path components */
  946 	raw_spin_lock_irqsave(&devtree_lock, flags);
  947 	if (!np)
  948 		np = of_node_get(of_root);
  949 	np = __of_find_node_by_full_path(np, path);
  950 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  951 	return np;
  952 }
  953 EXPORT_SYMBOL(of_find_node_opts_by_path);
  954 
  955 /**
  956  * of_find_node_by_name - Find a node by its "name" property
  957  * @from:	The node to start searching from or NULL; the node
  958  *		you pass will not be searched, only the next one
  959  *		will. Typically, you pass what the previous call
  960  *		returned. of_node_put() will be called on @from.
  961  * @name:	The name string to match against
  962  *
  963  * Return: A node pointer with refcount incremented, use
  964  * of_node_put() on it when done.
  965  */
  966 struct device_node *of_find_node_by_name(struct device_node *from,
  967 	const char *name)
  968 {
  969 	struct device_node *np;
  970 	unsigned long flags;
  971 
  972 	raw_spin_lock_irqsave(&devtree_lock, flags);
  973 	for_each_of_allnodes_from(from, np)
  974 		if (of_node_name_eq(np, name) && of_node_get(np))
  975 			break;
  976 	of_node_put(from);
  977 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  978 	return np;
  979 }
  980 EXPORT_SYMBOL(of_find_node_by_name);
  981 
  982 /**
  983  * of_find_node_by_type - Find a node by its "device_type" property
  984  * @from:	The node to start searching from, or NULL to start searching
  985  *		the entire device tree. The node you pass will not be
  986  *		searched, only the next one will; typically, you pass
  987  *		what the previous call returned. of_node_put() will be
  988  *		called on from for you.
  989  * @type:	The type string to match against
  990  *
  991  * Return: A node pointer with refcount incremented, use
  992  * of_node_put() on it when done.
  993  */
  994 struct device_node *of_find_node_by_type(struct device_node *from,
  995 	const char *type)
  996 {
  997 	struct device_node *np;
  998 	unsigned long flags;
  999 
 1000 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1001 	for_each_of_allnodes_from(from, np)
 1002 		if (__of_node_is_type(np, type) && of_node_get(np))
 1003 			break;
 1004 	of_node_put(from);
 1005 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1006 	return np;
 1007 }
 1008 EXPORT_SYMBOL(of_find_node_by_type);
 1009 
 1010 /**
 1011  * of_find_compatible_node - Find a node based on type and one of the
 1012  *                                tokens in its "compatible" property
 1013  * @from:	The node to start searching from or NULL, the node
 1014  *		you pass will not be searched, only the next one
 1015  *		will; typically, you pass what the previous call
 1016  *		returned. of_node_put() will be called on it
 1017  * @type:	The type string to match "device_type" or NULL to ignore
 1018  * @compatible:	The string to match to one of the tokens in the device
 1019  *		"compatible" list.
 1020  *
 1021  * Return: A node pointer with refcount incremented, use
 1022  * of_node_put() on it when done.
 1023  */
 1024 struct device_node *of_find_compatible_node(struct device_node *from,
 1025 	const char *type, const char *compatible)
 1026 {
 1027 	struct device_node *np;
 1028 	unsigned long flags;
 1029 
 1030 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1031 	for_each_of_allnodes_from(from, np)
 1032 		if (__of_device_is_compatible(np, compatible, type, NULL) &&
 1033 		    of_node_get(np))
 1034 			break;
 1035 	of_node_put(from);
 1036 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1037 	return np;
 1038 }
 1039 EXPORT_SYMBOL(of_find_compatible_node);
 1040 
 1041 /**
 1042  * of_find_node_with_property - Find a node which has a property with
 1043  *                              the given name.
 1044  * @from:	The node to start searching from or NULL, the node
 1045  *		you pass will not be searched, only the next one
 1046  *		will; typically, you pass what the previous call
 1047  *		returned. of_node_put() will be called on it
 1048  * @prop_name:	The name of the property to look for.
 1049  *
 1050  * Return: A node pointer with refcount incremented, use
 1051  * of_node_put() on it when done.
 1052  */
 1053 struct device_node *of_find_node_with_property(struct device_node *from,
 1054 	const char *prop_name)
 1055 {
 1056 	struct device_node *np;
 1057 	unsigned long flags;
 1058 
 1059 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1060 	for_each_of_allnodes_from(from, np) {
 1061 		if (__of_find_property(np, prop_name, NULL)) {
 1062 			of_node_get(np);
 1063 			break;
 1064 		}
 1065 	}
 1066 	of_node_put(from);
 1067 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1068 	return np;
 1069 }
 1070 EXPORT_SYMBOL(of_find_node_with_property);
 1071 
 1072 static
 1073 const struct of_device_id *__of_match_node(const struct of_device_id *matches,
 1074 					   const struct device_node *node)
 1075 {
 1076 	const struct of_device_id *best_match = NULL;
 1077 	int score, best_score = 0;
 1078 
 1079 	if (!matches)
 1080 		return NULL;
 1081 
 1082 	for (; matches->name[0] || matches->type[0] || matches->compatible[0]; matches++) {
 1083 		score = __of_device_is_compatible(node, matches->compatible,
 1084 						  matches->type, matches->name);
 1085 		if (score > best_score) {
 1086 			best_match = matches;
 1087 			best_score = score;
 1088 		}
 1089 	}
 1090 
 1091 	return best_match;
 1092 }
 1093 
 1094 /**
 1095  * of_match_node - Tell if a device_node has a matching of_match structure
 1096  * @matches:	array of of device match structures to search in
 1097  * @node:	the of device structure to match against
 1098  *
 1099  * Low level utility function used by device matching.
 1100  */
 1101 const struct of_device_id *of_match_node(const struct of_device_id *matches,
 1102 					 const struct device_node *node)
 1103 {
 1104 	const struct of_device_id *match;
 1105 	unsigned long flags;
 1106 
 1107 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1108 	match = __of_match_node(matches, node);
 1109 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1110 	return match;
 1111 }
 1112 EXPORT_SYMBOL(of_match_node);
 1113 
 1114 /**
 1115  * of_find_matching_node_and_match - Find a node based on an of_device_id
 1116  *				     match table.
 1117  * @from:	The node to start searching from or NULL, the node
 1118  *		you pass will not be searched, only the next one
 1119  *		will; typically, you pass what the previous call
 1120  *		returned. of_node_put() will be called on it
 1121  * @matches:	array of of device match structures to search in
 1122  * @match:	Updated to point at the matches entry which matched
 1123  *
 1124  * Return: A node pointer with refcount incremented, use
 1125  * of_node_put() on it when done.
 1126  */
 1127 struct device_node *of_find_matching_node_and_match(struct device_node *from,
 1128 					const struct of_device_id *matches,
 1129 					const struct of_device_id **match)
 1130 {
 1131 	struct device_node *np;
 1132 	const struct of_device_id *m;
 1133 	unsigned long flags;
 1134 
 1135 	if (match)
 1136 		*match = NULL;
 1137 
 1138 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1139 	for_each_of_allnodes_from(from, np) {
 1140 		m = __of_match_node(matches, np);
 1141 		if (m && of_node_get(np)) {
 1142 			if (match)
 1143 				*match = m;
 1144 			break;
 1145 		}
 1146 	}
 1147 	of_node_put(from);
 1148 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1149 	return np;
 1150 }
 1151 EXPORT_SYMBOL(of_find_matching_node_and_match);
 1152 
 1153 /**
 1154  * of_alias_from_compatible - Lookup appropriate alias for a device node
 1155  *			      depending on compatible
 1156  * @node:	pointer to a device tree node
 1157  * @alias:	Pointer to buffer that alias value will be copied into
 1158  * @len:	Length of alias value
 1159  *
 1160  * Based on the value of the compatible property, this routine will attempt
 1161  * to choose an appropriate alias value for a particular device tree node.
 1162  * It does this by stripping the manufacturer prefix (as delimited by a ',')
 1163  * from the first entry in the compatible list property.
 1164  *
 1165  * Note: The matching on just the "product" side of the compatible is a relic
 1166  * from I2C and SPI. Please do not add any new user.
 1167  *
 1168  * Return: This routine returns 0 on success, <0 on failure.
 1169  */
 1170 int of_alias_from_compatible(const struct device_node *node, char *alias, int len)
 1171 {
 1172 	const char *compatible, *p;
 1173 	int cplen;
 1174 
 1175 	compatible = of_get_property(node, "compatible", &cplen);
 1176 	if (!compatible || strlen(compatible) > cplen)
 1177 		return -ENODEV;
 1178 	p = strchr(compatible, ',');
 1179 	strscpy(alias, p ? p + 1 : compatible, len);
 1180 	return 0;
 1181 }
 1182 EXPORT_SYMBOL_GPL(of_alias_from_compatible);
 1183 
 1184 /**
 1185  * of_find_node_by_phandle - Find a node given a phandle
 1186  * @handle:	phandle of the node to find
 1187  *
 1188  * Return: A node pointer with refcount incremented, use
 1189  * of_node_put() on it when done.
 1190  */
 1191 struct device_node *of_find_node_by_phandle(phandle handle)
 1192 {
 1193 	struct device_node *np = NULL;
 1194 	unsigned long flags;
 1195 	u32 handle_hash;
 1196 
 1197 	if (!handle)
 1198 		return NULL;
 1199 
 1200 	handle_hash = of_phandle_cache_hash(handle);
 1201 
 1202 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1203 
 1204 	if (phandle_cache[handle_hash] &&
 1205 	    handle == phandle_cache[handle_hash]->phandle)
 1206 		np = phandle_cache[handle_hash];
 1207 
 1208 	if (!np) {
 1209 		for_each_of_allnodes(np)
 1210 			if (np->phandle == handle &&
 1211 			    !of_node_check_flag(np, OF_DETACHED)) {
 1212 				phandle_cache[handle_hash] = np;
 1213 				break;
 1214 			}
 1215 	}
 1216 
 1217 	of_node_get(np);
 1218 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1219 	return np;
 1220 }
 1221 EXPORT_SYMBOL(of_find_node_by_phandle);
 1222 
 1223 void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
 1224 {
 1225 	int i;
 1226 	printk("%s %pOF", msg, args->np);
 1227 	for (i = 0; i < args->args_count; i++) {
 1228 		const char delim = i ? ',' : ':';
 1229 
 1230 		pr_cont("%c%08x", delim, args->args[i]);
 1231 	}
 1232 	pr_cont("\n");
 1233 }
 1234 
 1235 int of_phandle_iterator_init(struct of_phandle_iterator *it,
 1236 		const struct device_node *np,
 1237 		const char *list_name,
 1238 		const char *cells_name,
 1239 		int cell_count)
 1240 {
 1241 	const __be32 *list;
 1242 	int size;
 1243 
 1244 	memset(it, 0, sizeof(*it));
 1245 
 1246 	/*
 1247 	 * one of cell_count or cells_name must be provided to determine the
 1248 	 * argument length.
 1249 	 */
 1250 	if (cell_count < 0 && !cells_name)
 1251 		return -EINVAL;
 1252 
 1253 	list = of_get_property(np, list_name, &size);
 1254 	if (!list)
 1255 		return -ENOENT;
 1256 
 1257 	it->cells_name = cells_name;
 1258 	it->cell_count = cell_count;
 1259 	it->parent = np;
 1260 	it->list_end = list + size / sizeof(*list);
 1261 	it->phandle_end = list;
 1262 	it->cur = list;
 1263 
 1264 	return 0;
 1265 }
 1266 EXPORT_SYMBOL_GPL(of_phandle_iterator_init);
 1267 
 1268 int of_phandle_iterator_next(struct of_phandle_iterator *it)
 1269 {
 1270 	uint32_t count = 0;
 1271 
 1272 	if (it->node) {
 1273 		of_node_put(it->node);
 1274 		it->node = NULL;
 1275 	}
 1276 
 1277 	if (!it->cur || it->phandle_end >= it->list_end)
 1278 		return -ENOENT;
 1279 
 1280 	it->cur = it->phandle_end;
 1281 
 1282 	/* If phandle is 0, then it is an empty entry with no arguments. */
 1283 	it->phandle = be32_to_cpup(it->cur++);
 1284 
 1285 	if (it->phandle) {
 1286 
 1287 		/*
 1288 		 * Find the provider node and parse the #*-cells property to
 1289 		 * determine the argument length.
 1290 		 */
 1291 		it->node = of_find_node_by_phandle(it->phandle);
 1292 
 1293 		if (it->cells_name) {
 1294 			if (!it->node) {
 1295 				pr_err("%pOF: could not find phandle %d\n",
 1296 				       it->parent, it->phandle);
 1297 				goto err;
 1298 			}
 1299 
 1300 			if (of_property_read_u32(it->node, it->cells_name,
 1301 						 &count)) {
 1302 				/*
 1303 				 * If both cell_count and cells_name is given,
 1304 				 * fall back to cell_count in absence
 1305 				 * of the cells_name property
 1306 				 */
 1307 				if (it->cell_count >= 0) {
 1308 					count = it->cell_count;
 1309 				} else {
 1310 					pr_err("%pOF: could not get %s for %pOF\n",
 1311 					       it->parent,
 1312 					       it->cells_name,
 1313 					       it->node);
 1314 					goto err;
 1315 				}
 1316 			}
 1317 		} else {
 1318 			count = it->cell_count;
 1319 		}
 1320 
 1321 		/*
 1322 		 * Make sure that the arguments actually fit in the remaining
 1323 		 * property data length
 1324 		 */
 1325 		if (it->cur + count > it->list_end) {
 1326 			if (it->cells_name)
 1327 				pr_err("%pOF: %s = %d found %td\n",
 1328 					it->parent, it->cells_name,
 1329 					count, it->list_end - it->cur);
 1330 			else
 1331 				pr_err("%pOF: phandle %s needs %d, found %td\n",
 1332 					it->parent, of_node_full_name(it->node),
 1333 					count, it->list_end - it->cur);
 1334 			goto err;
 1335 		}
 1336 	}
 1337 
 1338 	it->phandle_end = it->cur + count;
 1339 	it->cur_count = count;
 1340 
 1341 	return 0;
 1342 
 1343 err:
 1344 	if (it->node) {
 1345 		of_node_put(it->node);
 1346 		it->node = NULL;
 1347 	}
 1348 
 1349 	return -EINVAL;
 1350 }
 1351 EXPORT_SYMBOL_GPL(of_phandle_iterator_next);
 1352 
 1353 int 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 
 1370 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 	if (index < 0)
 1380 		return -EINVAL;
 1381 
 1382 	/* Loop over the phandles until all the requested entry is found */
 1383 	of_for_each_phandle(&it, rc, np, list_name, cells_name, cell_count) {
 1384 		/*
 1385 		 * All of the error cases bail out of the loop, so at
 1386 		 * this point, the parsing is successful. If the requested
 1387 		 * index matches, then fill the out_args structure and return,
 1388 		 * or return -ENOENT for an empty entry.
 1389 		 */
 1390 		rc = -ENOENT;
 1391 		if (cur_index == index) {
 1392 			if (!it.phandle)
 1393 				goto err;
 1394 
 1395 			if (out_args) {
 1396 				int c;
 1397 
 1398 				c = of_phandle_iterator_args(&it,
 1399 							     out_args->args,
 1400 							     MAX_PHANDLE_ARGS);
 1401 				out_args->np = it.node;
 1402 				out_args->args_count = c;
 1403 			} else {
 1404 				of_node_put(it.node);
 1405 			}
 1406 
 1407 			/* Found it! return success */
 1408 			return 0;
 1409 		}
 1410 
 1411 		cur_index++;
 1412 	}
 1413 
 1414 	/*
 1415 	 * Unlock node before returning result; will be one of:
 1416 	 * -ENOENT : index is for empty phandle
 1417 	 * -EINVAL : parsing error on data
 1418 	 */
 1419 
 1420  err:
 1421 	of_node_put(it.node);
 1422 	return rc;
 1423 }
 1424 EXPORT_SYMBOL(__of_parse_phandle_with_args);
 1425 
 1426 /**
 1427  * of_parse_phandle_with_args_map() - Find a node pointed by phandle in a list and remap it
 1428  * @np:		pointer to a device tree node containing a list
 1429  * @list_name:	property name that contains a list
 1430  * @stem_name:	stem of property names that specify phandles' arguments count
 1431  * @index:	index of a phandle to parse out
 1432  * @out_args:	optional pointer to output arguments structure (will be filled)
 1433  *
 1434  * This function is useful to parse lists of phandles and their arguments.
 1435  * Returns 0 on success and fills out_args, on error returns appropriate errno
 1436  * value. The difference between this function and of_parse_phandle_with_args()
 1437  * is that this API remaps a phandle if the node the phandle points to has
 1438  * a <@stem_name>-map property.
 1439  *
 1440  * Caller is responsible to call of_node_put() on the returned out_args->np
 1441  * pointer.
 1442  *
 1443  * Example::
 1444  *
 1445  *  phandle1: node1 {
 1446  *  	#list-cells = <2>;
 1447  *  };
 1448  *
 1449  *  phandle2: node2 {
 1450  *  	#list-cells = <1>;
 1451  *  };
 1452  *
 1453  *  phandle3: node3 {
 1454  *  	#list-cells = <1>;
 1455  *  	list-map = <0 &phandle2 3>,
 1456  *  		   <1 &phandle2 2>,
 1457  *  		   <2 &phandle1 5 1>;
 1458  *  	list-map-mask = <0x3>;
 1459  *  };
 1460  *
 1461  *  node4 {
 1462  *  	list = <&phandle1 1 2 &phandle3 0>;
 1463  *  };
 1464  *
 1465  * To get a device_node of the ``node2`` node you may call this:
 1466  * of_parse_phandle_with_args(node4, "list", "list", 1, &args);
 1467  */
 1468 int of_parse_phandle_with_args_map(const struct device_node *np,
 1469 				   const char *list_name,
 1470 				   const char *stem_name,
 1471 				   int index, struct of_phandle_args *out_args)
 1472 {
 1473 	char *cells_name __free(kfree) = kasprintf(GFP_KERNEL, "#%s-cells", stem_name);
 1474 	char *map_name __free(kfree) = kasprintf(GFP_KERNEL, "%s-map", stem_name);
 1475 	char *mask_name __free(kfree) = kasprintf(GFP_KERNEL, "%s-map-mask", stem_name);
 1476 	char *pass_name __free(kfree) = kasprintf(GFP_KERNEL, "%s-map-pass-thru", stem_name);
 1477 	struct device_node *cur, *new = NULL;
 1478 	const __be32 *map, *mask, *pass;
 1479 	static const __be32 dummy_mask[] = { [0 ... (MAX_PHANDLE_ARGS - 1)] = cpu_to_be32(~0) };
 1480 	static const __be32 dummy_pass[] = { [0 ... (MAX_PHANDLE_ARGS - 1)] = cpu_to_be32(0) };
 1481 	__be32 initial_match_array[MAX_PHANDLE_ARGS];
 1482 	const __be32 *match_array = initial_match_array;
 1483 	int i, ret, map_len, match;
 1484 	u32 list_size, new_size;
 1485 
 1486 	if (index < 0)
 1487 		return -EINVAL;
 1488 
 1489 	if (!cells_name || !map_name || !mask_name || !pass_name)
 1490 		return -ENOMEM;
 1491 
 1492 	ret = __of_parse_phandle_with_args(np, list_name, cells_name, -1, index,
 1493 					   out_args);
 1494 	if (ret)
 1495 		return ret;
 1496 
 1497 	/* Get the #<list>-cells property */
 1498 	cur = out_args->np;
 1499 	ret = of_property_read_u32(cur, cells_name, &list_size);
 1500 	if (ret < 0)
 1501 		goto put;
 1502 
 1503 	/* Precalculate the match array - this simplifies match loop */
 1504 	for (i = 0; i < list_size; i++)
 1505 		initial_match_array[i] = cpu_to_be32(out_args->args[i]);
 1506 
 1507 	ret = -EINVAL;
 1508 	while (cur) {
 1509 		/* Get the <list>-map property */
 1510 		map = of_get_property(cur, map_name, &map_len);
 1511 		if (!map) {
 1512 			return 0;
 1513 		}
 1514 		map_len /= sizeof(u32);
 1515 
 1516 		/* Get the <list>-map-mask property (optional) */
 1517 		mask = of_get_property(cur, mask_name, NULL);
 1518 		if (!mask)
 1519 			mask = dummy_mask;
 1520 		/* Iterate through <list>-map property */
 1521 		match = 0;
 1522 		while (map_len > (list_size + 1) && !match) {
 1523 			/* Compare specifiers */
 1524 			match = 1;
 1525 			for (i = 0; i < list_size; i++, map_len--)
 1526 				match &= !((match_array[i] ^ *map++) & mask[i]);
 1527 
 1528 			of_node_put(new);
 1529 			new = of_find_node_by_phandle(be32_to_cpup(map));
 1530 			map++;
 1531 			map_len--;
 1532 
 1533 			/* Check if not found */
 1534 			if (!new) {
 1535 				ret = -EINVAL;
 1536 				goto put;
 1537 			}
 1538 
 1539 			if (!of_device_is_available(new))
 1540 				match = 0;
 1541 
 1542 			ret = of_property_read_u32(new, cells_name, &new_size);
 1543 			if (ret)
 1544 				goto put;
 1545 
 1546 			/* Check for malformed properties */
 1547 			if (WARN_ON(new_size > MAX_PHANDLE_ARGS) ||
 1548 			    map_len < new_size) {
 1549 				ret = -EINVAL;
 1550 				goto put;
 1551 			}
 1552 
 1553 			/* Move forward by new node's #<list>-cells amount */
 1554 			map += new_size;
 1555 			map_len -= new_size;
 1556 		}
 1557 		if (!match) {
 1558 			ret = -ENOENT;
 1559 			goto put;
 1560 		}
 1561 
 1562 		/* Get the <list>-map-pass-thru property (optional) */
 1563 		pass = of_get_property(cur, pass_name, NULL);
 1564 		if (!pass)
 1565 			pass = dummy_pass;
 1566 
 1567 		/*
 1568 		 * Successfully parsed a <list>-map translation; copy new
 1569 		 * specifier into the out_args structure, keeping the
 1570 		 * bits specified in <list>-map-pass-thru.
 1571 		 */
 1572 		for (i = 0; i < new_size; i++) {
 1573 			__be32 val = *(map - new_size + i);
 1574 
 1575 			if (i < list_size) {
 1576 				val &= ~pass[i];
 1577 				val |= cpu_to_be32(out_args->args[i]) & pass[i];
 1578 			}
 1579 
 1580 			initial_match_array[i] = val;
 1581 			out_args->args[i] = be32_to_cpu(val);
 1582 		}
 1583 		out_args->args_count = list_size = new_size;
 1584 		/* Iterate again with new provider */
 1585 		out_args->np = new;
 1586 		of_node_put(cur);
 1587 		cur = new;
 1588 		new = NULL;
 1589 	}
 1590 put:
 1591 	of_node_put(cur);
 1592 	of_node_put(new);
 1593 	return ret;
 1594 }
 1595 EXPORT_SYMBOL(of_parse_phandle_with_args_map);
 1596 
 1597 /**
 1598  * of_count_phandle_with_args() - Find the number of phandles references in a property
 1599  * @np:		pointer to a device tree node containing a list
 1600  * @list_name:	property name that contains a list
 1601  * @cells_name:	property name that specifies phandles' arguments count
 1602  *
 1603  * Return: The number of phandle + argument tuples within a property. It
 1604  * is a typical pattern to encode a list of phandle and variable
 1605  * arguments into a single property. The number of arguments is encoded
 1606  * by a property in the phandle-target node. For example, a gpios
 1607  * property would contain a list of GPIO specifies consisting of a
 1608  * phandle and 1 or more arguments. The number of arguments are
 1609  * determined by the #gpio-cells property in the node pointed to by the
 1610  * phandle.
 1611  */
 1612 int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
 1613 				const char *cells_name)
 1614 {
 1615 	struct of_phandle_iterator it;
 1616 	int rc, cur_index = 0;
 1617 
 1618 	/*
 1619 	 * If cells_name is NULL we assume a cell count of 0. This makes
 1620 	 * counting the phandles trivial as each 32bit word in the list is a
 1621 	 * phandle and no arguments are to consider. So we don't iterate through
 1622 	 * the list but just use the length to determine the phandle count.
 1623 	 */
 1624 	if (!cells_name) {
 1625 		const __be32 *list;
 1626 		int size;
 1627 
 1628 		list = of_get_property(np, list_name, &size);
 1629 		if (!list)
 1630 			return -ENOENT;
 1631 
 1632 		return size / sizeof(*list);
 1633 	}
 1634 
 1635 	rc = of_phandle_iterator_init(&it, np, list_name, cells_name, -1);
 1636 	if (rc)
 1637 		return rc;
 1638 
 1639 	while ((rc = of_phandle_iterator_next(&it)) == 0)
 1640 		cur_index += 1;
 1641 
 1642 	if (rc != -ENOENT)
 1643 		return rc;
 1644 
 1645 	return cur_index;
 1646 }
 1647 EXPORT_SYMBOL(of_count_phandle_with_args);
 1648 
 1649 static struct property *__of_remove_property_from_list(struct property **list, struct property *prop)
 1650 {
 1651 	struct property **next;
 1652 
 1653 	for (next = list; *next; next = &(*next)->next) {
 1654 		if (*next == prop) {
 1655 			*next = prop->next;
 1656 			prop->next = NULL;
 1657 			return prop;
 1658 		}
 1659 	}
 1660 	return NULL;
 1661 }
 1662 
 1663 /**
 1664  * __of_add_property - Add a property to a node without lock operations
 1665  * @np:		Caller's Device Node
 1666  * @prop:	Property to add
 1667  */
 1668 int __of_add_property(struct device_node *np, struct property *prop)
 1669 {
 1670 	int rc = 0;
 1671 	unsigned long flags;
 1672 	struct property **next;
 1673 
 1674 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1675 
 1676 	__of_remove_property_from_list(&np->deadprops, prop);
 1677 
 1678 	prop->next = NULL;
 1679 	next = &np->properties;
 1680 	while (*next) {
 1681 		if (of_prop_cmp(prop->name, (*next)->name) == 0) {
 1682 			/* duplicate ! don't insert it */
 1683 			rc = -EEXIST;
 1684 			goto out_unlock;
 1685 		}
 1686 		next = &(*next)->next;
 1687 	}
 1688 	*next = prop;
 1689 
 1690 out_unlock:
 1691 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1692 	if (rc)
 1693 		return rc;
 1694 
 1695 	__of_add_property_sysfs(np, prop);
 1696 	return 0;
 1697 }
 1698 
 1699 /**
 1700  * of_add_property - Add a property to a node
 1701  * @np:		Caller's Device Node
 1702  * @prop:	Property to add
 1703  */
 1704 int of_add_property(struct device_node *np, struct property *prop)
 1705 {
 1706 	int rc;
 1707 
 1708 	mutex_lock(&of_mutex);
 1709 	rc = __of_add_property(np, prop);
 1710 	mutex_unlock(&of_mutex);
 1711 
 1712 	if (!rc)
 1713 		of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL);
 1714 
 1715 	return rc;
 1716 }
 1717 EXPORT_SYMBOL_GPL(of_add_property);
 1718 
 1719 int __of_remove_property(struct device_node *np, struct property *prop)
 1720 {
 1721 	unsigned long flags;
 1722 	int rc = -ENODEV;
 1723 
 1724 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1725 
 1726 	if (__of_remove_property_from_list(&np->properties, prop)) {
 1727 		/* Found the property, add it to deadprops list */
 1728 		prop->next = np->deadprops;
 1729 		np->deadprops = prop;
 1730 		rc = 0;
 1731 	}
 1732 
 1733 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1734 	if (rc)
 1735 		return rc;
 1736 
 1737 	__of_remove_property_sysfs(np, prop);
 1738 	return 0;
 1739 }
 1740 
 1741 /**
 1742  * of_remove_property - Remove a property from a node.
 1743  * @np:		Caller's Device Node
 1744  * @prop:	Property to remove
 1745  *
 1746  * Note that we don't actually remove it, since we have given out
 1747  * who-knows-how-many pointers to the data using get-property.
 1748  * Instead we just move the property to the "dead properties"
 1749  * list, so it won't be found any more.
 1750  */
 1751 int of_remove_property(struct device_node *np, struct property *prop)
 1752 {
 1753 	int rc;
 1754 
 1755 	if (!prop)
 1756 		return -ENODEV;
 1757 
 1758 	mutex_lock(&of_mutex);
 1759 	rc = __of_remove_property(np, prop);
 1760 	mutex_unlock(&of_mutex);
 1761 
 1762 	if (!rc)
 1763 		of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL);
 1764 
 1765 	return rc;
 1766 }
 1767 EXPORT_SYMBOL_GPL(of_remove_property);
 1768 
 1769 int __of_update_property(struct device_node *np, struct property *newprop,
 1770 		struct property **oldpropp)
 1771 {
 1772 	struct property **next, *oldprop;
 1773 	unsigned long flags;
 1774 
 1775 	raw_spin_lock_irqsave(&devtree_lock, flags);
 1776 
 1777 	__of_remove_property_from_list(&np->deadprops, newprop);
 1778 
 1779 	for (next = &np->properties; *next; next = &(*next)->next) {
 1780 		if (of_prop_cmp((*next)->name, newprop->name) == 0)
 1781 			break;
 1782 	}
 1783 	*oldpropp = oldprop = *next;
 1784 
 1785 	if (oldprop) {
 1786 		/* replace the node */
 1787 		newprop->next = oldprop->next;
 1788 		*next = newprop;
 1789 		oldprop->next = np->deadprops;
 1790 		np->deadprops = oldprop;
 1791 	} else {
 1792 		/* new node */
 1793 		newprop->next = NULL;
 1794 		*next = newprop;
 1795 	}
 1796 
 1797 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 1798 
 1799 	__of_update_property_sysfs(np, newprop, oldprop);
 1800 
 1801 	return 0;
 1802 }
 1803 
 1804 /*
 1805  * of_update_property - Update a property in a node, if the property does
 1806  * not exist, add it.
 1807  *
 1808  * Note that we don't actually remove it, since we have given out
 1809  * who-knows-how-many pointers to the data using get-property.
 1810  * Instead we just move the property to the "dead properties" list,
 1811  * and add the new property to the property list
 1812  */
 1813 int of_update_property(struct device_node *np, struct property *newprop)
 1814 {
 1815 	struct property *oldprop;
 1816 	int rc;
 1817 
 1818 	if (!newprop->name)
 1819 		return -EINVAL;
 1820 
 1821 	mutex_lock(&of_mutex);
 1822 	rc = __of_update_property(np, newprop, &oldprop);
 1823 	mutex_unlock(&of_mutex);
 1824 
 1825 	if (!rc)
 1826 		of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop);
 1827 
 1828 	return rc;
 1829 }
 1830 
 1831 static void of_alias_add(struct alias_prop *ap, struct device_node *np,
 1832 			 int id, const char *stem, int stem_len)
 1833 {
 1834 	ap->np = np;
 1835 	ap->id = id;
 1836 	strscpy(ap->stem, stem, stem_len + 1);
 1837 	list_add_tail(&ap->link, &aliases_lookup);
 1838 	pr_debug("adding DT alias:%s: stem=%s id=%i node=%pOF\n",
 1839 		 ap->alias, ap->stem, ap->id, np);
 1840 }
 1841 
 1842 /**
 1843  * of_alias_scan - Scan all properties of the 'aliases' node
 1844  * @dt_alloc:	An allocator that provides a virtual address to memory
 1845  *		for storing the resulting tree
 1846  *
 1847  * The function scans all the properties of the 'aliases' node and populates
 1848  * the global lookup table with the properties.
 1849  */
 1850 void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
 1851 {
 1852 	const struct property *pp;
 1853 
 1854 	of_aliases = of_find_node_by_path("/aliases");
 1855 	of_chosen = of_find_node_by_path("/chosen");
 1856 	if (of_chosen == NULL)
 1857 		of_chosen = of_find_node_by_path("/chosen@0");
 1858 
 1859 	if (of_chosen) {
 1860 		/* linux,stdout-path and /aliases/stdout are for legacy compatibility */
 1861 		const char *name = NULL;
 1862 
 1863 		if (of_property_read_string(of_chosen, "stdout-path", &name))
 1864 			of_property_read_string(of_chosen, "linux,stdout-path",
 1865 						&name);
 1866 		if (IS_ENABLED(CONFIG_PPC) && !name)
 1867 			of_property_read_string(of_aliases, "stdout", &name);
 1868 		if (name)
 1869 			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
 1870 		if (of_stdout)
 1871 			fwnode_set_flag(&of_stdout->fwnode, FWNODE_FLAG_BEST_EFFORT);
 1872 	}
 1873 
 1874 	if (!of_aliases)
 1875 		return;
 1876 
 1877 	for_each_property_of_node(of_aliases, pp) {
 1878 		const char *start = pp->name;
 1879 		const char *end = start + strlen(start);
 1880 		struct device_node *np;
 1881 		struct alias_prop *ap;
 1882 		int id, len;
 1883 
 1884 		/* Skip those we do not want to proceed */
 1885 		if (is_pseudo_property(pp->name))
 1886 			continue;
 1887 
 1888 		np = of_find_node_by_path(pp->value);
 1889 		if (!np)
 1890 			continue;
 1891 
 1892 		/* walk the alias backwards to extract the id and work out
 1893 		 * the 'stem' string */
 1894 		while (isdigit(*(end-1)) && end > start)
 1895 			end--;
 1896 		len = end - start;
 1897 
 1898 		if (kstrtoint(end, 10, &id) < 0) {
 1899 			of_node_put(np);
 1900 			continue;
 1901 		}
 1902 
 1903 		/* Allocate an alias_prop with enough space for the stem */
 1904 		ap = dt_alloc(sizeof(*ap) + len + 1, __alignof__(*ap));
 1905 		if (!ap) {
 1906 			of_node_put(np);
 1907 			continue;
 1908 		}
 1909 		memset(ap, 0, sizeof(*ap) + len + 1);
 1910 		ap->alias = start;
 1911 		of_alias_add(ap, np, id, start, len);
 1912 	}
 1913 }
 1914 
 1915 /**
 1916  * of_alias_get_id - Get alias id for the given device_node
 1917  * @np:		Pointer to the given device_node
 1918  * @stem:	Alias stem of the given device_node
 1919  *
 1920  * The function travels the lookup table to get the alias id for the given
 1921  * device_node and alias stem.
 1922  *
 1923  * Return: The alias id if found.
 1924  */
 1925 int of_alias_get_id(const struct device_node *np, const char *stem)
 1926 {
 1927 	struct alias_prop *app;
 1928 	int id = -ENODEV;
 1929 
 1930 	mutex_lock(&of_mutex);
 1931 	list_for_each_entry(app, &aliases_lookup, link) {
 1932 		if (strcmp(app->stem, stem) != 0)
 1933 			continue;
 1934 
 1935 		if (np == app->np) {
 1936 			id = app->id;
 1937 			break;
 1938 		}
 1939 	}
 1940 	mutex_unlock(&of_mutex);
 1941 
 1942 	return id;
 1943 }
 1944 EXPORT_SYMBOL_GPL(of_alias_get_id);
 1945 
 1946 /**
 1947  * of_alias_get_highest_id - Get highest alias id for the given stem
 1948  * @stem:	Alias stem to be examined
 1949  *
 1950  * The function travels the lookup table to get the highest alias id for the
 1951  * given alias stem.  It returns the alias id if found.
 1952  */
 1953 int of_alias_get_highest_id(const char *stem)
 1954 {
 1955 	struct alias_prop *app;
 1956 	int id = -ENODEV;
 1957 
 1958 	mutex_lock(&of_mutex);
 1959 	list_for_each_entry(app, &aliases_lookup, link) {
 1960 		if (strcmp(app->stem, stem) != 0)
 1961 			continue;
 1962 
 1963 		if (app->id > id)
 1964 			id = app->id;
 1965 	}
 1966 	mutex_unlock(&of_mutex);
 1967 
 1968 	return id;
 1969 }
 1970 EXPORT_SYMBOL_GPL(of_alias_get_highest_id);
 1971 
 1972 /**
 1973  * of_console_check() - Test and setup console for DT setup
 1974  * @dn: Pointer to device node
 1975  * @name: Name to use for preferred console without index. ex. "ttyS"
 1976  * @index: Index to use for preferred console.
 1977  *
 1978  * Check if the given device node matches the stdout-path property in the
 1979  * /chosen node. If it does then register it as the preferred console.
 1980  *
 1981  * Return: TRUE if console successfully setup. Otherwise return FALSE.
 1982  */
 1983 bool of_console_check(const struct device_node *dn, char *name, int index)
 1984 {
 1985 	if (!dn || dn != of_stdout || console_set_on_cmdline)
 1986 		return false;
 1987 
 1988 	/*
 1989 	 * XXX: cast `options' to char pointer to suppress complication
 1990 	 * warnings: printk, UART and console drivers expect char pointer.
 1991 	 */
 1992 	return !add_preferred_console(name, index, (char *)of_stdout_options);
 1993 }
 1994 EXPORT_SYMBOL_GPL(of_console_check);
 1995 
 1996 /**
 1997  * of_find_next_cache_node - Find a node's subsidiary cache
 1998  * @np:	node of type "cpu" or "cache"
 1999  *
 2000  * Return: A node pointer with refcount incremented, use
 2001  * of_node_put() on it when done.  Caller should hold a reference
 2002  * to np.
 2003  */
 2004 struct device_node *of_find_next_cache_node(const struct device_node *np)
 2005 {
 2006 	struct device_node *child, *cache_node;
 2007 
 2008 	cache_node = of_parse_phandle(np, "l2-cache", 0);
 2009 	if (!cache_node)
 2010 		cache_node = of_parse_phandle(np, "next-level-cache", 0);
 2011 
 2012 	if (cache_node)
 2013 		return cache_node;
 2014 
 2015 	/* OF on pmac has nodes instead of properties named "l2-cache"
 2016 	 * beneath CPU nodes.
 2017 	 */
 2018 	if (IS_ENABLED(CONFIG_PPC_PMAC) && of_node_is_type(np, "cpu"))
 2019 		for_each_child_of_node(np, child)
 2020 			if (of_node_is_type(child, "cache"))
 2021 				return child;
 2022 
 2023 	return NULL;
 2024 }
 2025 
 2026 /**
 2027  * of_find_last_cache_level - Find the level at which the last cache is
 2028  * 		present for the given logical cpu
 2029  *
 2030  * @cpu: cpu number(logical index) for which the last cache level is needed
 2031  *
 2032  * Return: The level at which the last cache is present. It is exactly
 2033  * same as  the total number of cache levels for the given logical cpu.
 2034  */
 2035 int of_find_last_cache_level(unsigned int cpu)
 2036 {
 2037 	u32 cache_level = 0;
 2038 	struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
 2039 
 2040 	while (np) {
 2041 		of_node_put(prev);
 2042 		prev = np;
 2043 		np = of_find_next_cache_node(np);
 2044 	}
 2045 
 2046 	of_property_read_u32(prev, "cache-level", &cache_level);
 2047 	of_node_put(prev);
 2048 
 2049 	return cache_level;
 2050 }
 2051 
 2052 /**
 2053  * of_map_id - Translate an ID through a downstream mapping.
 2054  * @np: root complex device node.
 2055  * @id: device ID to map.
 2056  * @map_name: property name of the map to use.
 2057  * @map_mask_name: optional property name of the mask to use.
 2058  * @target: optional pointer to a target device node.
 2059  * @id_out: optional pointer to receive the translated ID.
 2060  *
 2061  * Given a device ID, look up the appropriate implementation-defined
 2062  * platform ID and/or the target device which receives transactions on that
 2063  * ID, as per the "iommu-map" and "msi-map" bindings. Either of @target or
 2064  * @id_out may be NULL if only the other is required. If @target points to
 2065  * a non-NULL device node pointer, only entries targeting that node will be
 2066  * matched; if it points to a NULL value, it will receive the device node of
 2067  * the first matching target phandle, with a reference held.
 2068  *
 2069  * Return: 0 on success or a standard error code on failure.
 2070  */
 2071 int of_map_id(const struct device_node *np, u32 id,
 2072 	       const char *map_name, const char *map_mask_name,
 2073 	       struct device_node **target, u32 *id_out)
 2074 {
 2075 	u32 map_mask, masked_id;
 2076 	int map_len;
 2077 	const __be32 *map = NULL;
 2078 
 2079 	if (!np || !map_name || (!target && !id_out))
 2080 		return -EINVAL;
 2081 
 2082 	map = of_get_property(np, map_name, &map_len);
 2083 	if (!map) {
 2084 		if (target)
 2085 			return -ENODEV;
 2086 		/* Otherwise, no map implies no translation */
 2087 		*id_out = id;
 2088 		return 0;
 2089 	}
 2090 
 2091 	if (!map_len || map_len % (4 * sizeof(*map))) {
 2092 		pr_err("%pOF: Error: Bad %s length: %d\n", np,
 2093 			map_name, map_len);
 2094 		return -EINVAL;
 2095 	}
 2096 
 2097 	/* The default is to select all bits. */
 2098 	map_mask = 0xffffffff;
 2099 
 2100 	/*
 2101 	 * Can be overridden by "{iommu,msi}-map-mask" property.
 2102 	 * If of_property_read_u32() fails, the default is used.
 2103 	 */
 2104 	if (map_mask_name)
 2105 		of_property_read_u32(np, map_mask_name, &map_mask);
 2106 
 2107 	masked_id = map_mask & id;
 2108 	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
 2109 		struct device_node *phandle_node;
 2110 		u32 id_base = be32_to_cpup(map + 0);
 2111 		u32 phandle = be32_to_cpup(map + 1);
 2112 		u32 out_base = be32_to_cpup(map + 2);
 2113 		u32 id_len = be32_to_cpup(map + 3);
 2114 
 2115 		if (id_base & ~map_mask) {
 2116 			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
 2117 				np, map_name, map_name,
 2118 				map_mask, id_base);
 2119 			return -EFAULT;
 2120 		}
 2121 
 2122 		if (masked_id < id_base || masked_id >= id_base + id_len)
 2123 			continue;
 2124 
 2125 		phandle_node = of_find_node_by_phandle(phandle);
 2126 		if (!phandle_node)
 2127 			return -ENODEV;
 2128 
 2129 		if (target) {
 2130 			if (*target)
 2131 				of_node_put(phandle_node);
 2132 			else
 2133 				*target = phandle_node;
 2134 
 2135 			if (*target != phandle_node)
 2136 				continue;
 2137 		}
 2138 
 2139 		if (id_out)
 2140 			*id_out = masked_id - id_base + out_base;
 2141 
 2142 		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
 2143 			np, map_name, map_mask, id_base, out_base,
 2144 			id_len, id, masked_id - id_base + out_base);
 2145 		return 0;
 2146 	}
 2147 
 2148 	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
 2149 		id, target && *target ? *target : NULL);
 2150 
 2151 	/* Bypasses translation */
 2152 	if (id_out)
 2153 		*id_out = id;
 2154 	return 0;
 2155 }
 2156 EXPORT_SYMBOL_GPL(of_map_id);