// SPDX-License-Identifier: GPL-2.0+

  /*
   * Procedures for creating, accessing and interpreting the device tree.
   *
   * Paul Mackerras	August 1996.
   * Copyright (C) 1996-2005 Paul Mackerras.
   *
   *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
   *    {engebret|bergner}@us.ibm.com
   *
   *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
   *

   *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
   *  Grant Likely.

   */

  
  #define pr_fmt(fmt)	"OF: " fmt

  #include <linux/console.h>

  #include <linux/ctype.h>

  #include <linux/cpu.h>

  #include <linux/module.h>
  #include <linux/of.h>

  #include <linux/of_device.h>

  #include <linux/of_graph.h>

  #include <linux/spinlock.h>

  #include <linux/slab.h>

  #include <linux/string.h>

  #include <linux/proc_fs.h>

  #include "of_private.h"

  LIST_HEAD(aliases_lookup);

  struct device_node *of_root;
  EXPORT_SYMBOL(of_root);

  struct device_node *of_chosen;

  struct device_node *of_aliases;

  struct device_node *of_stdout;

  static const char *of_stdout_options;

  struct kset *of_kset;

  
  /*

   * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
   * This mutex must be held whenever modifications are being made to the
   * device tree. The of_{attach,detach}_node() and
   * of_{add,remove,update}_property() helpers make sure this happens.

   */

  DEFINE_MUTEX(of_mutex);

  /* use when traversing tree through the child, sibling,

   * or parent members of struct device_node.
   */

  DEFINE_RAW_SPINLOCK(devtree_lock);

  bool of_node_name_eq(const struct device_node *np, const char *name)
  {
  	const char *node_name;
  	size_t len;
  
  	if (!np)
  		return false;
  
  	node_name = kbasename(np->full_name);
  	len = strchrnul(node_name, '@') - node_name;
  
  	return (strlen(name) == len) && (strncmp(node_name, name, len) == 0);
  }

  EXPORT_SYMBOL(of_node_name_eq);

  
  bool of_node_name_prefix(const struct device_node *np, const char *prefix)
  {
  	if (!np)
  		return false;
  
  	return strncmp(kbasename(np->full_name), prefix, strlen(prefix)) == 0;
  }

  EXPORT_SYMBOL(of_node_name_prefix);

  int of_n_addr_cells(struct device_node *np)
  {

  	u32 cells;

  
  	do {
  		if (np->parent)
  			np = np->parent;

  		if (!of_property_read_u32(np, "#address-cells", &cells))
  			return cells;

  	} while (np->parent);
  	/* No #address-cells property for the root node */
  	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  }
  EXPORT_SYMBOL(of_n_addr_cells);
  
  int of_n_size_cells(struct device_node *np)
  {

  	u32 cells;

  
  	do {
  		if (np->parent)
  			np = np->parent;

  		if (!of_property_read_u32(np, "#size-cells", &cells))
  			return cells;

  	} while (np->parent);
  	/* No #size-cells property for the root node */
  	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  }
  EXPORT_SYMBOL(of_n_size_cells);

  #ifdef CONFIG_NUMA
  int __weak of_node_to_nid(struct device_node *np)
  {

  	return NUMA_NO_NODE;

  }
  #endif

  /*
   * Assumptions behind phandle_cache implementation:
   *   - phandle property values are in a contiguous range of 1..n
   *
   * If the assumptions do not hold, then
   *   - the phandle lookup overhead reduction provided by the cache
   *     will likely be less
   */

  
  static struct device_node **phandle_cache;
  static u32 phandle_cache_mask;
  
  /*
   * Caller must hold devtree_lock.
   */
  static void __of_free_phandle_cache(void)
  {
  	u32 cache_entries = phandle_cache_mask + 1;
  	u32 k;
  
  	if (!phandle_cache)
  		return;
  
  	for (k = 0; k < cache_entries; k++)
  		of_node_put(phandle_cache[k]);
  
  	kfree(phandle_cache);
  	phandle_cache = NULL;
  }
  
  int of_free_phandle_cache(void)
  {
  	unsigned long flags;
  
  	raw_spin_lock_irqsave(&devtree_lock, flags);
  
  	__of_free_phandle_cache();
  
  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  
  	return 0;
  }
  #if !defined(CONFIG_MODULES)
  late_initcall_sync(of_free_phandle_cache);
  #endif

  /*
   * Caller must hold devtree_lock.
   */
  void __of_free_phandle_cache_entry(phandle handle)
  {
  	phandle masked_handle;
  	struct device_node *np;
  
  	if (!handle)
  		return;
  
  	masked_handle = handle & phandle_cache_mask;
  
  	if (phandle_cache) {
  		np = phandle_cache[masked_handle];
  		if (np && handle == np->phandle) {
  			of_node_put(np);
  			phandle_cache[masked_handle] = NULL;
  		}
  	}
  }

  void of_populate_phandle_cache(void)

  {
  	unsigned long flags;
  	u32 cache_entries;
  	struct device_node *np;
  	u32 phandles = 0;
  
  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	__of_free_phandle_cache();

  
  	for_each_of_allnodes(np)
  		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
  			phandles++;

  	if (!phandles)
  		goto out;

  	cache_entries = roundup_pow_of_two(phandles);
  	phandle_cache_mask = cache_entries - 1;
  
  	phandle_cache = kcalloc(cache_entries, sizeof(*phandle_cache),
  				GFP_ATOMIC);
  	if (!phandle_cache)
  		goto out;
  
  	for_each_of_allnodes(np)

  		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) {
  			of_node_get(np);

  			phandle_cache[np->phandle & phandle_cache_mask] = np;

  		}

  
  out:
  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  }

  void __init of_core_init(void)

  {
  	struct device_node *np;

  	of_populate_phandle_cache();

  	/* Create the kset, and register existing nodes */

  	mutex_lock(&of_mutex);

  	of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
  	if (!of_kset) {

  		mutex_unlock(&of_mutex);

  		pr_err("failed to register existing nodes
  ");

  		return;

  	}
  	for_each_of_allnodes(np)

  		__of_attach_node_sysfs(np);

  	mutex_unlock(&of_mutex);

  	/* Symlink in /proc as required by userspace ABI */

  	if (of_root)

  		proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");

  }

  static struct property *__of_find_property(const struct device_node *np,
  					   const char *name, int *lenp)

  {
  	struct property *pp;

  	if (!np)
  		return NULL;

  	for (pp = np->properties; pp; pp = pp->next) {

  		if (of_prop_cmp(pp->name, name) == 0) {

  			if (lenp)

  				*lenp = pp->length;
  			break;
  		}
  	}

  
  	return pp;
  }
  
  struct property *of_find_property(const struct device_node *np,
  				  const char *name,
  				  int *lenp)
  {
  	struct property *pp;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	pp = __of_find_property(np, name, lenp);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  
  	return pp;
  }
  EXPORT_SYMBOL(of_find_property);

  struct device_node *__of_find_all_nodes(struct device_node *prev)
  {
  	struct device_node *np;
  	if (!prev) {
  		np = of_root;
  	} else if (prev->child) {
  		np = prev->child;
  	} else {
  		/* Walk back up looking for a sibling, or the end of the structure */
  		np = prev;
  		while (np->parent && !np->sibling)
  			np = np->parent;
  		np = np->sibling; /* Might be null at the end of the tree */
  	}
  	return np;
  }

  /**
   * of_find_all_nodes - Get next node in global list
   * @prev:	Previous node or NULL to start iteration
   *		of_node_put() will be called on it
   *
   * Returns a node pointer with refcount incremented, use
   * of_node_put() on it when done.
   */
  struct device_node *of_find_all_nodes(struct device_node *prev)
  {
  	struct device_node *np;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	np = __of_find_all_nodes(prev);
  	of_node_get(np);

  	of_node_put(prev);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_all_nodes);

  /*
   * Find a property with a given name for a given node
   * and return the value.
   */

  const void *__of_get_property(const struct device_node *np,
  			      const char *name, int *lenp)

  {
  	struct property *pp = __of_find_property(np, name, lenp);
  
  	return pp ? pp->value : NULL;
  }
  
  /*
   * Find a property with a given name for a given node
   * and return the value.
   */

  const void *of_get_property(const struct device_node *np, const char *name,

  			    int *lenp)

  {
  	struct property *pp = of_find_property(np, name, lenp);
  
  	return pp ? pp->value : NULL;
  }
  EXPORT_SYMBOL(of_get_property);

  /*
   * arch_match_cpu_phys_id - Match the given logical CPU and physical id
   *
   * @cpu: logical cpu index of a core/thread
   * @phys_id: physical identifier of a core/thread
   *
   * CPU logical to physical index mapping is architecture specific.
   * However this __weak function provides a default match of physical
   * id to logical cpu index. phys_id provided here is usually values read
   * from the device tree which must match the hardware internal registers.
   *
   * Returns true if the physical identifier and the logical cpu index
   * correspond to the same core/thread, false otherwise.
   */
  bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
  {
  	return (u32)phys_id == cpu;
  }
  
  /**
   * Checks if the given "prop_name" property holds the physical id of the
   * core/thread corresponding to the logical cpu 'cpu'. If 'thread' is not
   * NULL, local thread number within the core is returned in it.
   */
  static bool __of_find_n_match_cpu_property(struct device_node *cpun,
  			const char *prop_name, int cpu, unsigned int *thread)
  {
  	const __be32 *cell;
  	int ac, prop_len, tid;
  	u64 hwid;
  
  	ac = of_n_addr_cells(cpun);
  	cell = of_get_property(cpun, prop_name, &prop_len);

  	if (!cell || !ac)

  		return false;

  	prop_len /= sizeof(*cell) * ac;

  	for (tid = 0; tid < prop_len; tid++) {
  		hwid = of_read_number(cell, ac);
  		if (arch_match_cpu_phys_id(cpu, hwid)) {
  			if (thread)
  				*thread = tid;
  			return true;
  		}
  		cell += ac;
  	}
  	return false;
  }

  /*
   * arch_find_n_match_cpu_physical_id - See if the given device node is
   * for the cpu corresponding to logical cpu 'cpu'.  Return true if so,
   * else false.  If 'thread' is non-NULL, the local thread number within the
   * core is returned in it.
   */
  bool __weak arch_find_n_match_cpu_physical_id(struct device_node *cpun,
  					      int cpu, unsigned int *thread)
  {
  	/* Check for non-standard "ibm,ppc-interrupt-server#s" property
  	 * for thread ids on PowerPC. If it doesn't exist fallback to
  	 * standard "reg" property.
  	 */
  	if (IS_ENABLED(CONFIG_PPC) &&
  	    __of_find_n_match_cpu_property(cpun,
  					   "ibm,ppc-interrupt-server#s",
  					   cpu, thread))
  		return true;

  	return __of_find_n_match_cpu_property(cpun, "reg", cpu, thread);

  }

  /**
   * of_get_cpu_node - Get device node associated with the given logical CPU
   *
   * @cpu: CPU number(logical index) for which device node is required
   * @thread: if not NULL, local thread number within the physical core is
   *          returned
   *
   * The main purpose of this function is to retrieve the device node for the
   * given logical CPU index. It should be used to initialize the of_node in
   * cpu device. Once of_node in cpu device is populated, all the further
   * references can use that instead.
   *
   * CPU logical to physical index mapping is architecture specific and is built
   * before booting secondary cores. This function uses arch_match_cpu_phys_id
   * which can be overridden by architecture specific implementation.
   *

   * Returns a node pointer for the logical cpu with refcount incremented, use
   * of_node_put() on it when done. Returns NULL if not found.

   */
  struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
  {

  	struct device_node *cpun;

  	for_each_node_by_type(cpun, "cpu") {
  		if (arch_find_n_match_cpu_physical_id(cpun, cpu, thread))

  			return cpun;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL(of_get_cpu_node);

  /**

   * of_cpu_node_to_id: Get the logical CPU number for a given device_node
   *
   * @cpu_node: Pointer to the device_node for CPU.
   *
   * Returns the logical CPU number of the given CPU device_node.
   * Returns -ENODEV if the CPU is not found.
   */
  int of_cpu_node_to_id(struct device_node *cpu_node)
  {
  	int cpu;
  	bool found = false;
  	struct device_node *np;
  
  	for_each_possible_cpu(cpu) {
  		np = of_cpu_device_node_get(cpu);
  		found = (cpu_node == np);
  		of_node_put(np);
  		if (found)
  			return cpu;
  	}
  
  	return -ENODEV;
  }
  EXPORT_SYMBOL(of_cpu_node_to_id);
  
  /**

   * __of_device_is_compatible() - Check if the node matches given constraints
   * @device: pointer to node
   * @compat: required compatible string, NULL or "" for any match
   * @type: required device_type value, NULL or "" for any match
   * @name: required node name, NULL or "" for any match
   *
   * Checks if the given @compat, @type and @name strings match the
   * properties of the given @device. A constraints can be skipped by
   * passing NULL or an empty string as the constraint.
   *
   * Returns 0 for no match, and a positive integer on match. The return
   * value is a relative score with larger values indicating better
   * matches. The score is weighted for the most specific compatible value
   * to get the highest score. Matching type is next, followed by matching
   * name. Practically speaking, this results in the following priority
   * order for matches:
   *
   * 1. specific compatible && type && name
   * 2. specific compatible && type
   * 3. specific compatible && name
   * 4. specific compatible
   * 5. general compatible && type && name
   * 6. general compatible && type
   * 7. general compatible && name
   * 8. general compatible
   * 9. type && name
   * 10. type
   * 11. name

   */

  static int __of_device_is_compatible(const struct device_node *device,

  				     const char *compat, const char *type, const char *name)
  {
  	struct property *prop;
  	const char *cp;
  	int index = 0, score = 0;
  
  	/* Compatible match has highest priority */
  	if (compat && compat[0]) {
  		prop = __of_find_property(device, "compatible", NULL);
  		for (cp = of_prop_next_string(prop, NULL); cp;
  		     cp = of_prop_next_string(prop, cp), index++) {
  			if (of_compat_cmp(cp, compat, strlen(compat)) == 0) {
  				score = INT_MAX/2 - (index << 2);
  				break;
  			}
  		}
  		if (!score)
  			return 0;
  	}

  	/* Matching type is better than matching name */
  	if (type && type[0]) {
  		if (!device->type || of_node_cmp(type, device->type))
  			return 0;
  		score += 2;

  	}

  	/* Matching name is a bit better than not */
  	if (name && name[0]) {
  		if (!device->name || of_node_cmp(name, device->name))
  			return 0;
  		score++;
  	}
  
  	return score;

  }

  
  /** Checks if the given "compat" string matches one of the strings in
   * the device's "compatible" property
   */
  int of_device_is_compatible(const struct device_node *device,
  		const char *compat)
  {

  	unsigned long flags;

  	int res;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	res = __of_device_is_compatible(device, compat, NULL, NULL);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return res;
  }

  EXPORT_SYMBOL(of_device_is_compatible);

  /** Checks if the device is compatible with any of the entries in
   *  a NULL terminated array of strings. Returns the best match
   *  score or 0.
   */
  int of_device_compatible_match(struct device_node *device,
  			       const char *const *compat)
  {
  	unsigned int tmp, score = 0;
  
  	if (!compat)
  		return 0;
  
  	while (*compat) {
  		tmp = of_device_is_compatible(device, *compat);
  		if (tmp > score)
  			score = tmp;
  		compat++;
  	}
  
  	return score;
  }

  /**

   * of_machine_is_compatible - Test root of device tree for a given compatible value

   * @compat: compatible string to look for in root node's compatible property.
   *

   * Returns a positive integer if the root node has the given value in its

   * compatible property.
   */

  int of_machine_is_compatible(const char *compat)

  {
  	struct device_node *root;
  	int rc = 0;
  
  	root = of_find_node_by_path("/");
  	if (root) {
  		rc = of_device_is_compatible(root, compat);
  		of_node_put(root);
  	}
  	return rc;
  }

  EXPORT_SYMBOL(of_machine_is_compatible);

  
  /**

   *  __of_device_is_available - check if a device is available for use

   *

   *  @device: Node to check for availability, with locks already held

   *

   *  Returns true if the status property is absent or set to "okay" or "ok",
   *  false otherwise

   */

  static bool __of_device_is_available(const struct device_node *device)

  {
  	const char *status;
  	int statlen;

  	if (!device)

  		return false;

  	status = __of_get_property(device, "status", &statlen);

  	if (status == NULL)

  		return true;

  
  	if (statlen > 0) {
  		if (!strcmp(status, "okay") || !strcmp(status, "ok"))

  			return true;

  	}

  	return false;

  }

  
  /**
   *  of_device_is_available - check if a device is available for use
   *
   *  @device: Node to check for availability
   *

   *  Returns true if the status property is absent or set to "okay" or "ok",
   *  false otherwise

   */

  bool of_device_is_available(const struct device_node *device)

  {
  	unsigned long flags;

  	bool res;

  
  	raw_spin_lock_irqsave(&devtree_lock, flags);
  	res = __of_device_is_available(device);
  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
  	return res;
  
  }

  EXPORT_SYMBOL(of_device_is_available);
  
  /**

   *  of_device_is_big_endian - check if a device has BE registers
   *
   *  @device: Node to check for endianness
   *
   *  Returns true if the device has a "big-endian" property, or if the kernel
   *  was compiled for BE *and* the device has a "native-endian" property.
   *  Returns false otherwise.
   *
   *  Callers would nominally use ioread32be/iowrite32be if
   *  of_device_is_big_endian() == true, or readl/writel otherwise.
   */
  bool of_device_is_big_endian(const struct device_node *device)
  {
  	if (of_property_read_bool(device, "big-endian"))
  		return true;
  	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
  	    of_property_read_bool(device, "native-endian"))
  		return true;
  	return false;
  }
  EXPORT_SYMBOL(of_device_is_big_endian);
  
  /**

   *	of_get_parent - Get a node's parent if any
   *	@node:	Node to get parent
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_get_parent(const struct device_node *node)
  {
  	struct device_node *np;

  	unsigned long flags;

  
  	if (!node)
  		return NULL;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	np = of_node_get(node->parent);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_get_parent);

  
  /**

   *	of_get_next_parent - Iterate to a node's parent
   *	@node:	Node to get parent of
   *

   *	This is like of_get_parent() except that it drops the
   *	refcount on the passed node, making it suitable for iterating
   *	through a node's parents.

   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_get_next_parent(struct device_node *node)
  {
  	struct device_node *parent;

  	unsigned long flags;

  
  	if (!node)
  		return NULL;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	parent = of_node_get(node->parent);
  	of_node_put(node);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return parent;
  }

  EXPORT_SYMBOL(of_get_next_parent);

  static struct device_node *__of_get_next_child(const struct device_node *node,
  						struct device_node *prev)
  {
  	struct device_node *next;

  	if (!node)
  		return NULL;

  	next = prev ? prev->sibling : node->child;
  	for (; next; next = next->sibling)
  		if (of_node_get(next))
  			break;
  	of_node_put(prev);
  	return next;
  }
  #define __for_each_child_of_node(parent, child) \
  	for (child = __of_get_next_child(parent, NULL); child != NULL; \
  	     child = __of_get_next_child(parent, child))

  /**

   *	of_get_next_child - Iterate a node childs
   *	@node:	parent node
   *	@prev:	previous child of the parent node, or NULL to get first
   *

   *	Returns a node pointer with refcount incremented, use of_node_put() on
   *	it when done. Returns NULL when prev is the last child. Decrements the
   *	refcount of prev.

   */
  struct device_node *of_get_next_child(const struct device_node *node,
  	struct device_node *prev)
  {
  	struct device_node *next;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	next = __of_get_next_child(node, prev);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return next;
  }
  EXPORT_SYMBOL(of_get_next_child);

  
  /**

   *	of_get_next_available_child - Find the next available child node
   *	@node:	parent node
   *	@prev:	previous child of the parent node, or NULL to get first
   *
   *      This function is like of_get_next_child(), except that it
   *      automatically skips any disabled nodes (i.e. status = "disabled").
   */
  struct device_node *of_get_next_available_child(const struct device_node *node,
  	struct device_node *prev)
  {
  	struct device_node *next;

  	unsigned long flags;

  	if (!node)
  		return NULL;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	next = prev ? prev->sibling : node->child;
  	for (; next; next = next->sibling) {

  		if (!__of_device_is_available(next))

  			continue;
  		if (of_node_get(next))
  			break;
  	}
  	of_node_put(prev);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return next;
  }
  EXPORT_SYMBOL(of_get_next_available_child);
  
  /**

   * of_get_compatible_child - Find compatible child node
   * @parent:	parent node
   * @compatible:	compatible string
   *
   * Lookup child node whose compatible property contains the given compatible
   * string.
   *
   * Returns a node pointer with refcount incremented, use of_node_put() on it
   * when done; or NULL if not found.
   */
  struct device_node *of_get_compatible_child(const struct device_node *parent,
  				const char *compatible)
  {
  	struct device_node *child;
  
  	for_each_child_of_node(parent, child) {
  		if (of_device_is_compatible(child, compatible))
  			break;
  	}
  
  	return child;
  }
  EXPORT_SYMBOL(of_get_compatible_child);
  
  /**

   *	of_get_child_by_name - Find the child node by name for a given parent
   *	@node:	parent node
   *	@name:	child name to look for.
   *
   *      This function looks for child node for given matching name
   *
   *	Returns a node pointer if found, with refcount incremented, use
   *	of_node_put() on it when done.
   *	Returns NULL if node is not found.
   */
  struct device_node *of_get_child_by_name(const struct device_node *node,
  				const char *name)
  {
  	struct device_node *child;
  
  	for_each_child_of_node(node, child)
  		if (child->name && (of_node_cmp(child->name, name) == 0))
  			break;
  	return child;
  }
  EXPORT_SYMBOL(of_get_child_by_name);

  struct device_node *__of_find_node_by_path(struct device_node *parent,

  						const char *path)
  {
  	struct device_node *child;

  	int len;

  	len = strcspn(path, "/:");

  	if (!len)
  		return NULL;
  
  	__for_each_child_of_node(parent, child) {

  		const char *name = kbasename(child->full_name);

  		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
  			return child;
  	}
  	return NULL;
  }

  struct device_node *__of_find_node_by_full_path(struct device_node *node,
  						const char *path)
  {
  	const char *separator = strchr(path, ':');
  
  	while (node && *path == '/') {
  		struct device_node *tmp = node;
  
  		path++; /* Increment past '/' delimiter */
  		node = __of_find_node_by_path(node, path);
  		of_node_put(tmp);
  		path = strchrnul(path, '/');
  		if (separator && separator < path)
  			break;
  	}
  	return node;
  }

  /**

   *	of_find_node_opts_by_path - Find a node matching a full OF path

   *	@path: Either the full path to match, or if the path does not
   *	       start with '/', the name of a property of the /aliases
   *	       node (an alias).  In the case of an alias, the node
   *	       matching the alias' value will be returned.

   *	@opts: Address of a pointer into which to store the start of
   *	       an options string appended to the end of the path with
   *	       a ':' separator.

   *
   *	Valid paths:
   *		/foo/bar	Full path
   *		foo		Valid alias
   *		foo/bar		Valid alias + relative path

   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */

  struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)

  {

  	struct device_node *np = NULL;
  	struct property *pp;

  	unsigned long flags;

  	const char *separator = strchr(path, ':');
  
  	if (opts)
  		*opts = separator ? separator + 1 : NULL;

  	if (strcmp(path, "/") == 0)

  		return of_node_get(of_root);

  
  	/* The path could begin with an alias */
  	if (*path != '/') {

  		int len;
  		const char *p = separator;
  
  		if (!p)
  			p = strchrnul(path, '/');
  		len = p - path;

  
  		/* of_aliases must not be NULL */
  		if (!of_aliases)
  			return NULL;
  
  		for_each_property_of_node(of_aliases, pp) {
  			if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
  				np = of_find_node_by_path(pp->value);
  				break;
  			}
  		}
  		if (!np)
  			return NULL;
  		path = p;
  	}
  
  	/* Step down the tree matching path components */

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	if (!np)

  		np = of_node_get(of_root);

  	np = __of_find_node_by_full_path(np, path);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }

  EXPORT_SYMBOL(of_find_node_opts_by_path);

  
  /**
   *	of_find_node_by_name - Find a node by its "name" property

   *	@from:	The node to start searching from or NULL; the node

   *		you pass will not be searched, only the next one

   *		will. Typically, you pass what the previous call
   *		returned. of_node_put() will be called on @from.

   *	@name:	The name string to match against
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_node_by_name(struct device_node *from,
  	const char *name)
  {
  	struct device_node *np;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	for_each_of_allnodes_from(from, np)

  		if (np->name && (of_node_cmp(np->name, name) == 0)
  		    && of_node_get(np))
  			break;
  	of_node_put(from);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_node_by_name);
  
  /**
   *	of_find_node_by_type - Find a node by its "device_type" property
   *	@from:	The node to start searching from, or NULL to start searching
   *		the entire device tree. The node you pass will not be
   *		searched, only the next one will; typically, you pass
   *		what the previous call returned. of_node_put() will be
   *		called on from for you.
   *	@type:	The type string to match against
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_node_by_type(struct device_node *from,
  	const char *type)
  {
  	struct device_node *np;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	for_each_of_allnodes_from(from, np)

  		if (np->type && (of_node_cmp(np->type, type) == 0)
  		    && of_node_get(np))
  			break;
  	of_node_put(from);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_node_by_type);
  
  /**
   *	of_find_compatible_node - Find a node based on type and one of the
   *                                tokens in its "compatible" property
   *	@from:		The node to start searching from or NULL, the node
   *			you pass will not be searched, only the next one
   *			will; typically, you pass what the previous call
   *			returned. of_node_put() will be called on it
   *	@type:		The type string to match "device_type" or NULL to ignore
   *	@compatible:	The string to match to one of the tokens in the device
   *			"compatible" list.
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_compatible_node(struct device_node *from,
  	const char *type, const char *compatible)
  {
  	struct device_node *np;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	for_each_of_allnodes_from(from, np)

  		if (__of_device_is_compatible(np, compatible, type, NULL) &&

  		    of_node_get(np))

  			break;

  	of_node_put(from);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_compatible_node);

  
  /**

   *	of_find_node_with_property - Find a node which has a property with
   *                                   the given name.
   *	@from:		The node to start searching from or NULL, the node
   *			you pass will not be searched, only the next one
   *			will; typically, you pass what the previous call
   *			returned. of_node_put() will be called on it
   *	@prop_name:	The name of the property to look for.
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_node_with_property(struct device_node *from,
  	const char *prop_name)
  {
  	struct device_node *np;
  	struct property *pp;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	for_each_of_allnodes_from(from, np) {

  		for (pp = np->properties; pp; pp = pp->next) {

  			if (of_prop_cmp(pp->name, prop_name) == 0) {
  				of_node_get(np);
  				goto out;
  			}
  		}
  	}
  out:
  	of_node_put(from);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_node_with_property);

  static
  const struct of_device_id *__of_match_node(const struct of_device_id *matches,
  					   const struct device_node *node)

  {

  	const struct of_device_id *best_match = NULL;
  	int score, best_score = 0;

  	if (!matches)
  		return NULL;

  	for (; matches->name[0] || matches->type[0] || matches->compatible[0]; matches++) {
  		score = __of_device_is_compatible(node, matches->compatible,
  						  matches->type, matches->name);
  		if (score > best_score) {
  			best_match = matches;
  			best_score = score;
  		}

  	}

  
  	return best_match;

  }

  
  /**

   * of_match_node - Tell if a device_node has a matching of_match structure

   *	@matches:	array of of device match structures to search in
   *	@node:		the of device structure to match against
   *

   *	Low level utility function used by device matching.

   */
  const struct of_device_id *of_match_node(const struct of_device_id *matches,
  					 const struct device_node *node)
  {
  	const struct of_device_id *match;

  	unsigned long flags;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	match = __of_match_node(matches, node);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return match;
  }

  EXPORT_SYMBOL(of_match_node);
  
  /**

   *	of_find_matching_node_and_match - Find a node based on an of_device_id
   *					  match table.

   *	@from:		The node to start searching from or NULL, the node
   *			you pass will not be searched, only the next one
   *			will; typically, you pass what the previous call
   *			returned. of_node_put() will be called on it
   *	@matches:	array of of device match structures to search in

   *	@match		Updated to point at the matches entry which matched

   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */

  struct device_node *of_find_matching_node_and_match(struct device_node *from,
  					const struct of_device_id *matches,
  					const struct of_device_id **match)

  {
  	struct device_node *np;

  	const struct of_device_id *m;

  	unsigned long flags;

  	if (match)
  		*match = NULL;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	for_each_of_allnodes_from(from, np) {

  		m = __of_match_node(matches, np);

  		if (m && of_node_get(np)) {

  			if (match)

  				*match = m;

  			break;

  		}

  	}
  	of_node_put(from);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }

  EXPORT_SYMBOL(of_find_matching_node_and_match);

  
  /**

   * of_modalias_node - Lookup appropriate modalias for a device node
   * @node:	pointer to a device tree node
   * @modalias:	Pointer to buffer that modalias value will be copied into
   * @len:	Length of modalias value
   *

   * Based on the value of the compatible property, this routine will attempt
   * to choose an appropriate modalias value for a particular device tree node.
   * It does this by stripping the manufacturer prefix (as delimited by a ',')
   * from the first entry in the compatible list property.

   *

   * This routine returns 0 on success, <0 on failure.

   */
  int of_modalias_node(struct device_node *node, char *modalias, int len)
  {

  	const char *compatible, *p;
  	int cplen;

  
  	compatible = of_get_property(node, "compatible", &cplen);

  	if (!compatible || strlen(compatible) > cplen)

  		return -ENODEV;

  	p = strchr(compatible, ',');

  	strlcpy(modalias, p ? p + 1 : compatible, len);

  	return 0;
  }
  EXPORT_SYMBOL_GPL(of_modalias_node);

  /**

   * of_find_node_by_phandle - Find a node given a phandle
   * @handle:	phandle of the node to find
   *
   * Returns a node pointer with refcount incremented, use
   * of_node_put() on it when done.
   */
  struct device_node *of_find_node_by_phandle(phandle handle)
  {

  	struct device_node *np = NULL;

  	unsigned long flags;

  	phandle masked_handle;

  	if (!handle)
  		return NULL;

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  
  	masked_handle = handle & phandle_cache_mask;
  
  	if (phandle_cache) {
  		if (phandle_cache[masked_handle] &&
  		    handle == phandle_cache[masked_handle]->phandle)
  			np = phandle_cache[masked_handle];

  		if (np && of_node_check_flag(np, OF_DETACHED)) {
  			WARN_ON(1); /* did not uncache np on node removal */
  			of_node_put(np);
  			phandle_cache[masked_handle] = NULL;
  			np = NULL;
  		}

  	}
  
  	if (!np) {
  		for_each_of_allnodes(np)

  			if (np->phandle == handle &&
  			    !of_node_check_flag(np, OF_DETACHED)) {

  				if (phandle_cache) {
  					/* will put when removed from cache */
  					of_node_get(np);

  					phandle_cache[masked_handle] = np;

  				}

  				break;
  			}
  	}

  	of_node_get(np);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	return np;
  }
  EXPORT_SYMBOL(of_find_node_by_phandle);

  void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
  {
  	int i;

  	printk("%s %pOF", msg, args->np);

  	for (i = 0; i < args->args_count; i++) {
  		const char delim = i ? ',' : ':';
  
  		pr_cont("%c%08x", delim, args->args[i]);
  	}
  	pr_cont("
  ");

  }

  int of_phandle_iterator_init(struct of_phandle_iterator *it,
  		const struct device_node *np,
  		const char *list_name,
  		const char *cells_name,
  		int cell_count)

  {

  	const __be32 *list;
  	int size;
  
  	memset(it, 0, sizeof(*it));

  
  	list = of_get_property(np, list_name, &size);

  	if (!list)

  		return -ENOENT;

  	it->cells_name = cells_name;
  	it->cell_count = cell_count;
  	it->parent = np;
  	it->list_end = list + size / sizeof(*list);
  	it->phandle_end = list;
  	it->cur = list;
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(of_phandle_iterator_init);

  int of_phandle_iterator_next(struct of_phandle_iterator *it)
  {
  	uint32_t count = 0;
  
  	if (it->node) {
  		of_node_put(it->node);
  		it->node = NULL;
  	}
  
  	if (!it->cur || it->phandle_end >= it->list_end)
  		return -ENOENT;
  
  	it->cur = it->phandle_end;
  
  	/* If phandle is 0, then it is an empty entry with no arguments. */
  	it->phandle = be32_to_cpup(it->cur++);
  
  	if (it->phandle) {

  		/*

  		 * Find the provider node and parse the #*-cells property to
  		 * determine the argument length.

  		 */

  		it->node = of_find_node_by_phandle(it->phandle);

  		if (it->cells_name) {
  			if (!it->node) {

  				pr_err("%pOF: could not find phandle
  ",
  				       it->parent);

  				goto err;

  			}

  			if (of_property_read_u32(it->node, it->cells_name,
  						 &count)) {

  				pr_err("%pOF: could not get %s for %pOF
  ",
  				       it->parent,

  				       it->cells_name,

  				       it->node);

  				goto err;

  			}

  		} else {
  			count = it->cell_count;

  		}

  		/*

  		 * Make sure that the arguments actually fit in the remaining
  		 * property data length
  		 */
  		if (it->cur + count > it->list_end) {

  			pr_err("%pOF: arguments longer than property
  ",
  			       it->parent);

  			goto err;
  		}
  	}
  
  	it->phandle_end = it->cur + count;
  	it->cur_count = count;
  
  	return 0;
  
  err:
  	if (it->node) {
  		of_node_put(it->node);
  		it->node = NULL;
  	}
  
  	return -EINVAL;
  }

  EXPORT_SYMBOL_GPL(of_phandle_iterator_next);

  int of_phandle_iterator_args(struct of_phandle_iterator *it,
  			     uint32_t *args,
  			     int size)
  {
  	int i, count;
  
  	count = it->cur_count;
  
  	if (WARN_ON(size < count))
  		count = size;
  
  	for (i = 0; i < count; i++)
  		args[i] = be32_to_cpup(it->cur++);
  
  	return count;
  }

  static int __of_parse_phandle_with_args(const struct device_node *np,
  					const char *list_name,

  					const char *cells_name,
  					int cell_count, int index,

  					struct of_phandle_args *out_args)

  {

  	struct of_phandle_iterator it;
  	int rc, cur_index = 0;

  	/* Loop over the phandles until all the requested entry is found */

  	of_for_each_phandle(&it, rc, np, list_name, cells_name, cell_count) {

  		/*

  		 * All of the error cases bail out of the loop, so at

  		 * this point, the parsing is successful. If the requested
  		 * index matches, then fill the out_args structure and return,
  		 * or return -ENOENT for an empty entry.
  		 */

  		rc = -ENOENT;

  		if (cur_index == index) {

  			if (!it.phandle)

  				goto err;

  
  			if (out_args) {

  				int c;
  
  				c = of_phandle_iterator_args(&it,
  							     out_args->args,
  							     MAX_PHANDLE_ARGS);

  				out_args->np = it.node;

  				out_args->args_count = c;

  			} else {

  				of_node_put(it.node);

  			}

  
  			/* Found it! return success */

  			return 0;

  		}

  		cur_index++;
  	}

  	/*
  	 * Unlock node before returning result; will be one of:
  	 * -ENOENT : index is for empty phandle
  	 * -EINVAL : parsing error on data
  	 */

   err:

  	of_node_put(it.node);

  	return rc;

  }

  /**

   * of_parse_phandle - Resolve a phandle property to a device_node pointer
   * @np: Pointer to device node holding phandle property
   * @phandle_name: Name of property holding a phandle value
   * @index: For properties holding a table of phandles, this is the index into
   *         the table
   *
   * Returns the device_node pointer with refcount incremented.  Use
   * of_node_put() on it when done.
   */
  struct device_node *of_parse_phandle(const struct device_node *np,
  				     const char *phandle_name, int index)
  {

  	struct of_phandle_args args;
  
  	if (index < 0)
  		return NULL;

  	if (__of_parse_phandle_with_args(np, phandle_name, NULL, 0,
  					 index, &args))

  		return NULL;

  	return args.np;

  }
  EXPORT_SYMBOL(of_parse_phandle);
  
  /**

   * of_parse_phandle_with_args() - Find a node pointed by phandle in a list
   * @np:		pointer to a device tree node containing a list
   * @list_name:	property name that contains a list
   * @cells_name:	property name that specifies phandles' arguments count
   * @index:	index of a phandle to parse out
   * @out_args:	optional pointer to output arguments structure (will be filled)
   *
   * This function is useful to parse lists of phandles and their arguments.
   * Returns 0 on success and fills out_args, on error returns appropriate
   * errno value.
   *

   * Caller is responsible to call of_node_put() on the returned out_args->np

   * pointer.
   *
   * Example:
   *
   * phandle1: node1 {

   *	#list-cells = <2>;

   * }
   *
   * phandle2: node2 {

   *	#list-cells = <1>;

   * }
   *
   * node3 {

   *	list = <&phandle1 1 2 &phandle2 3>;

   * }
   *
   * To get a device_node of the `node2' node you may call this:
   * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args);
   */

  int of_parse_phandle_with_args(const struct device_node *np, const char *list_name,
  				const char *cells_name, int index,
  				struct of_phandle_args *out_args)
  {
  	if (index < 0)
  		return -EINVAL;

  	return __of_parse_phandle_with_args(np, list_name, cells_name, 0,
  					    index, out_args);

  }

  EXPORT_SYMBOL(of_parse_phandle_with_args);

  /**

   * of_parse_phandle_with_args_map() - Find a node pointed by phandle in a list and remap it
   * @np:		pointer to a device tree node containing a list
   * @list_name:	property name that contains a list
   * @stem_name:	stem of property names that specify phandles' arguments count
   * @index:	index of a phandle to parse out
   * @out_args:	optional pointer to output arguments structure (will be filled)
   *
   * This function is useful to parse lists of phandles and their arguments.
   * Returns 0 on success and fills out_args, on error returns appropriate errno
   * value. The difference between this function and of_parse_phandle_with_args()
   * is that this API remaps a phandle if the node the phandle points to has
   * a <@stem_name>-map property.
   *
   * Caller is responsible to call of_node_put() on the returned out_args->np
   * pointer.
   *
   * Example:
   *
   * phandle1: node1 {
   *	#list-cells = <2>;
   * }
   *
   * phandle2: node2 {
   *	#list-cells = <1>;
   * }
   *
   * phandle3: node3 {
   * 	#list-cells = <1>;
   * 	list-map = <0 &phandle2 3>,
   * 		   <1 &phandle2 2>,
   * 		   <2 &phandle1 5 1>;
   *	list-map-mask = <0x3>;
   * };
   *
   * node4 {
   *	list = <&phandle1 1 2 &phandle3 0>;
   * }
   *
   * To get a device_node of the `node2' node you may call this:
   * of_parse_phandle_with_args(node4, "list", "list", 1, &args);
   */
  int of_parse_phandle_with_args_map(const struct device_node *np,
  				   const char *list_name,
  				   const char *stem_name,
  				   int index, struct of_phandle_args *out_args)
  {
  	char *cells_name, *map_name = NULL, *mask_name = NULL;
  	char *pass_name = NULL;
  	struct device_node *cur, *new = NULL;
  	const __be32 *map, *mask, *pass;
  	static const __be32 dummy_mask[] = { [0 ... MAX_PHANDLE_ARGS] = ~0 };
  	static const __be32 dummy_pass[] = { [0 ... MAX_PHANDLE_ARGS] = 0 };
  	__be32 initial_match_array[MAX_PHANDLE_ARGS];
  	const __be32 *match_array = initial_match_array;
  	int i, ret, map_len, match;
  	u32 list_size, new_size;
  
  	if (index < 0)
  		return -EINVAL;
  
  	cells_name = kasprintf(GFP_KERNEL, "#%s-cells", stem_name);
  	if (!cells_name)
  		return -ENOMEM;
  
  	ret = -ENOMEM;
  	map_name = kasprintf(GFP_KERNEL, "%s-map", stem_name);
  	if (!map_name)
  		goto free;
  
  	mask_name = kasprintf(GFP_KERNEL, "%s-map-mask", stem_name);
  	if (!mask_name)
  		goto free;
  
  	pass_name = kasprintf(GFP_KERNEL, "%s-map-pass-thru", stem_name);
  	if (!pass_name)
  		goto free;
  
  	ret = __of_parse_phandle_with_args(np, list_name, cells_name, 0, index,
  					   out_args);
  	if (ret)
  		goto free;
  
  	/* Get the #<list>-cells property */
  	cur = out_args->np;
  	ret = of_property_read_u32(cur, cells_name, &list_size);
  	if (ret < 0)
  		goto put;
  
  	/* Precalculate the match array - this simplifies match loop */
  	for (i = 0; i < list_size; i++)
  		initial_match_array[i] = cpu_to_be32(out_args->args[i]);
  
  	ret = -EINVAL;
  	while (cur) {
  		/* Get the <list>-map property */
  		map = of_get_property(cur, map_name, &map_len);
  		if (!map) {
  			ret = 0;
  			goto free;
  		}
  		map_len /= sizeof(u32);
  
  		/* Get the <list>-map-mask property (optional) */
  		mask = of_get_property(cur, mask_name, NULL);
  		if (!mask)
  			mask = dummy_mask;
  		/* Iterate through <list>-map property */
  		match = 0;
  		while (map_len > (list_size + 1) && !match) {
  			/* Compare specifiers */
  			match = 1;
  			for (i = 0; i < list_size; i++, map_len--)
  				match &= !((match_array[i] ^ *map++) & mask[i]);
  
  			of_node_put(new);
  			new = of_find_node_by_phandle(be32_to_cpup(map));
  			map++;
  			map_len--;
  
  			/* Check if not found */
  			if (!new)
  				goto put;
  
  			if (!of_device_is_available(new))
  				match = 0;
  
  			ret = of_property_read_u32(new, cells_name, &new_size);
  			if (ret)
  				goto put;
  
  			/* Check for malformed properties */
  			if (WARN_ON(new_size > MAX_PHANDLE_ARGS))
  				goto put;
  			if (map_len < new_size)
  				goto put;
  
  			/* Move forward by new node's #<list>-cells amount */
  			map += new_size;
  			map_len -= new_size;
  		}
  		if (!match)
  			goto put;
  
  		/* Get the <list>-map-pass-thru property (optional) */
  		pass = of_get_property(cur, pass_name, NULL);
  		if (!pass)
  			pass = dummy_pass;
  
  		/*
  		 * Successfully parsed a <list>-map translation; copy new
  		 * specifier into the out_args structure, keeping the
  		 * bits specified in <list>-map-pass-thru.
  		 */
  		match_array = map - new_size;
  		for (i = 0; i < new_size; i++) {
  			__be32 val = *(map - new_size + i);
  
  			if (i < list_size) {
  				val &= ~pass[i];
  				val |= cpu_to_be32(out_args->args[i]) & pass[i];
  			}
  
  			out_args->args[i] = be32_to_cpu(val);
  		}
  		out_args->args_count = list_size = new_size;
  		/* Iterate again with new provider */
  		out_args->np = new;
  		of_node_put(cur);
  		cur = new;
  	}
  put:
  	of_node_put(cur);
  	of_node_put(new);
  free:
  	kfree(mask_name);
  	kfree(map_name);
  	kfree(cells_name);
  	kfree(pass_name);
  
  	return ret;
  }
  EXPORT_SYMBOL(of_parse_phandle_with_args_map);
  
  /**

   * of_parse_phandle_with_fixed_args() - Find a node pointed by phandle in a list
   * @np:		pointer to a device tree node containing a list
   * @list_name:	property name that contains a list
   * @cell_count: number of argument cells following the phandle
   * @index:	index of a phandle to parse out
   * @out_args:	optional pointer to output arguments structure (will be filled)
   *
   * This function is useful to parse lists of phandles and their arguments.
   * Returns 0 on success and fills out_args, on error returns appropriate
   * errno value.
   *

   * Caller is responsible to call of_node_put() on the returned out_args->np

   * pointer.
   *
   * Example:
   *
   * phandle1: node1 {
   * }
   *
   * phandle2: node2 {
   * }
   *
   * node3 {

   *	list = <&phandle1 0 2 &phandle2 2 3>;

   * }
   *
   * To get a device_node of the `node2' node you may call this:
   * of_parse_phandle_with_fixed_args(node3, "list", 2, 1, &args);
   */
  int of_parse_phandle_with_fixed_args(const struct device_node *np,
  				const char *list_name, int cell_count,
  				int index, struct of_phandle_args *out_args)
  {
  	if (index < 0)
  		return -EINVAL;
  	return __of_parse_phandle_with_args(np, list_name, NULL, cell_count,
  					   index, out_args);
  }
  EXPORT_SYMBOL(of_parse_phandle_with_fixed_args);
  
  /**

   * of_count_phandle_with_args() - Find the number of phandles references in a property
   * @np:		pointer to a device tree node containing a list
   * @list_name:	property name that contains a list
   * @cells_name:	property name that specifies phandles' arguments count
   *
   * Returns the number of phandle + argument tuples within a property. It
   * is a typical pattern to encode a list of phandle and variable
   * arguments into a single property. The number of arguments is encoded
   * by a property in the phandle-target node. For example, a gpios
   * property would contain a list of GPIO specifies consisting of a
   * phandle and 1 or more arguments. The number of arguments are
   * determined by the #gpio-cells property in the node pointed to by the
   * phandle.
   */
  int of_count_phandle_with_args(const struct device_node *np, const char *list_name,
  				const char *cells_name)
  {

  	struct of_phandle_iterator it;
  	int rc, cur_index = 0;
  
  	rc = of_phandle_iterator_init(&it, np, list_name, cells_name, 0);
  	if (rc)
  		return rc;
  
  	while ((rc = of_phandle_iterator_next(&it)) == 0)
  		cur_index += 1;
  
  	if (rc != -ENOENT)
  		return rc;
  
  	return cur_index;

  }
  EXPORT_SYMBOL(of_count_phandle_with_args);

  /**

   * __of_add_property - Add a property to a node without lock operations
   */

  int __of_add_property(struct device_node *np, struct property *prop)

  {
  	struct property **next;
  
  	prop->next = NULL;
  	next = &np->properties;
  	while (*next) {
  		if (strcmp(prop->name, (*next)->name) == 0)
  			/* duplicate ! don't insert it */
  			return -EEXIST;
  
  		next = &(*next)->next;
  	}
  	*next = prop;
  
  	return 0;
  }
  
  /**

   * of_add_property - Add a property to a node

   */

  int of_add_property(struct device_node *np, struct property *prop)

  {

  	unsigned long flags;

  	int rc;

  	mutex_lock(&of_mutex);

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	rc = __of_add_property(np, prop);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	if (!rc)

  		__of_add_property_sysfs(np, prop);

  	mutex_unlock(&of_mutex);

  	if (!rc)
  		of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL);

  	return rc;

  }

  int __of_remove_property(struct device_node *np, struct property *prop)
  {
  	struct property **next;
  
  	for (next = &np->properties; *next; next = &(*next)->next) {
  		if (*next == prop)
  			break;
  	}
  	if (*next == NULL)
  		return -ENODEV;
  
  	/* found the node */
  	*next = prop->next;
  	prop->next = np->deadprops;
  	np->deadprops = prop;
  
  	return 0;
  }

  /**

   * of_remove_property - Remove a property from a node.

   *
   * Note that we don't actually remove it, since we have given out
   * who-knows-how-many pointers to the data using get-property.
   * Instead we just move the property to the "dead properties"
   * list, so it won't be found any more.
   */

  int of_remove_property(struct device_node *np, struct property *prop)

  {

  	unsigned long flags;

  	int rc;

  	if (!prop)
  		return -ENODEV;

  	mutex_lock(&of_mutex);

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	rc = __of_remove_property(np, prop);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	if (!rc)
  		__of_remove_property_sysfs(np, prop);

  	mutex_unlock(&of_mutex);

  	if (!rc)
  		of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL);

  	return rc;

  }

  int __of_update_property(struct device_node *np, struct property *newprop,
  		struct property **oldpropp)

  {

  	struct property **next, *oldprop;

  	for (next = &np->properties; *next; next = &(*next)->next) {
  		if (of_prop_cmp((*next)->name, newprop->name) == 0)
  			break;
  	}
  	*oldpropp = oldprop = *next;

  	if (oldprop) {

  		/* replace the node */

  		newprop->next = oldprop->next;
  		*next = newprop;
  		oldprop->next = np->deadprops;
  		np->deadprops = oldprop;
  	} else {
  		/* new node */
  		newprop->next = NULL;
  		*next = newprop;

  	}

  	return 0;
  }

  /*

   * of_update_property - Update a property in a node, if the property does

   * not exist, add it.

   *

   * Note that we don't actually remove it, since we have given out
   * who-knows-how-many pointers to the data using get-property.
   * Instead we just move the property to the "dead properties" list,
   * and add the new property to the property list

   */

  int of_update_property(struct device_node *np, struct property *newprop)

  {

  	struct property *oldprop;

  	unsigned long flags;

  	int rc;

  	if (!newprop->name)
  		return -EINVAL;

  	mutex_lock(&of_mutex);

  	raw_spin_lock_irqsave(&devtree_lock, flags);

  	rc = __of_update_property(np, newprop, &oldprop);

  	raw_spin_unlock_irqrestore(&devtree_lock, flags);

  	if (!rc)
  		__of_update_property_sysfs(np, newprop, oldprop);

  	mutex_unlock(&of_mutex);

  	if (!rc)
  		of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop);

  	return rc;

  }

  static void of_alias_add(struct alias_prop *ap, struct device_node *np,
  			 int id, const char *stem, int stem_len)
  {
  	ap->np = np;
  	ap->id = id;
  	strncpy(ap->stem, stem, stem_len);
  	ap->stem[stem_len] = 0;
  	list_add_tail(&ap->link, &aliases_lookup);

  	pr_debug("adding DT alias:%s: stem=%s id=%i node=%pOF
  ",
  		 ap->alias, ap->stem, ap->id, np);

  }

  /*
   * of_alias_max_index() - get the maximum index for a given alias stem
   * @stem:   The alias stem for which the maximum index is searched for
   *
   * Given an alias stem (the alias without the number) this function
   * returns the maximum number for which an alias exists.
   *
   * Return: The maximum existing alias index or -ENODEV if no alias
   *         exists for this stem.
   */
  int of_alias_max_index(const char *stem)
  {
  	struct alias_prop *app;
  	int max = -ENODEV;
  
  	mutex_lock(&of_mutex);
  
  	list_for_each_entry(app, &aliases_lookup, link) {
  		if (strcmp(app->stem, stem))
  			continue;
  		if (app->id > max)
  			max = app->id;
  	}
  
  	mutex_unlock(&of_mutex);
  
  	return max;
  }
  EXPORT_SYMBOL_GPL(of_alias_max_index);

  /**

   * of_alias_scan - Scan all properties of the 'aliases' node

   *

   * The function scans all the properties of the 'aliases' node and populates
   * the global lookup table with the properties.  It returns the
   * number of alias properties found, or an error code in case of failure.

   *
   * @dt_alloc:	An allocator that provides a virtual address to memory

   *		for storing the resulting tree

   */
  void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
  {
  	struct property *pp;

  	of_aliases = of_find_node_by_path("/aliases");

  	of_chosen = of_find_node_by_path("/chosen");
  	if (of_chosen == NULL)
  		of_chosen = of_find_node_by_path("/chosen@0");

  
  	if (of_chosen) {

  		/* linux,stdout-path and /aliases/stdout are for legacy compatibility */

  		const char *name = NULL;
  
  		if (of_property_read_string(of_chosen, "stdout-path", &name))
  			of_property_read_string(of_chosen, "linux,stdout-path",
  						&name);

  		if (IS_ENABLED(CONFIG_PPC) && !name)

  			of_property_read_string(of_aliases, "stdout", &name);

  		if (name)

  			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);

  	}

  	if (!of_aliases)
  		return;

  	for_each_property_of_node(of_aliases, pp) {

  		const char *start = pp->name;
  		const char *end = start + strlen(start);
  		struct device_node *np;
  		struct alias_prop *ap;
  		int id, len;
  
  		/* Skip those we do not want to proceed */
  		if (!strcmp(pp->name, "name") ||
  		    !strcmp(pp->name, "phandle") ||
  		    !strcmp(pp->name, "linux,phandle"))
  			continue;
  
  		np = of_find_node_by_path(pp->value);
  		if (!np)
  			continue;
  
  		/* walk the alias backwards to extract the id and work out
  		 * the 'stem' string */
  		while (isdigit(*(end-1)) && end > start)
  			end--;
  		len = end - start;
  
  		if (kstrtoint(end, 10, &id) < 0)
  			continue;
  
  		/* Allocate an alias_prop with enough space for the stem */

  		ap = dt_alloc(sizeof(*ap) + len + 1, __alignof__(*ap));

  		if (!ap)
  			continue;

  		memset(ap, 0, sizeof(*ap) + len + 1);

  		ap->alias = start;
  		of_alias_add(ap, np, id, start, len);
  	}
  }
  
  /**
   * of_alias_get_id - Get alias id for the given device_node
   * @np:		Pointer to the given device_node
   * @stem:	Alias stem of the given device_node
   *

   * The function travels the lookup table to get the alias id for the given
   * device_node and alias stem.  It returns the alias id if found.

   */
  int of_alias_get_id(struct device_node *np, const char *stem)
  {
  	struct alias_prop *app;
  	int id = -ENODEV;

  	mutex_lock(&of_mutex);

  	list_for_each_entry(app, &aliases_lookup, link) {
  		if (strcmp(app->stem, stem) != 0)
  			continue;
  
  		if (np == app->np) {
  			id = app->id;
  			break;
  		}
  	}

  	mutex_unlock(&of_mutex);

  
  	return id;
  }
  EXPORT_SYMBOL_GPL(of_alias_get_id);

  /**
   * of_alias_get_highest_id - Get highest alias id for the given stem
   * @stem:	Alias stem to be examined
   *
   * The function travels the lookup table to get the highest alias id for the
   * given alias stem.  It returns the alias id if found.
   */
  int of_alias_get_highest_id(const char *stem)
  {
  	struct alias_prop *app;
  	int id = -ENODEV;
  
  	mutex_lock(&of_mutex);
  	list_for_each_entry(app, &aliases_lookup, link) {
  		if (strcmp(app->stem, stem) != 0)
  			continue;
  
  		if (app->id > id)
  			id = app->id;
  	}
  	mutex_unlock(&of_mutex);
  
  	return id;
  }
  EXPORT_SYMBOL_GPL(of_alias_get_highest_id);

  /**

   * of_console_check() - Test and setup console for DT setup
   * @dn - Pointer to device node
   * @name - Name to use for preferred console without index. ex. "ttyS"
   * @index - Index to use for preferred console.
   *
   * Check if the given device node matches the stdout-path property in the
   * /chosen node. If it does then register it as the preferred console and return
   * TRUE. Otherwise return FALSE.

   */

  bool of_console_check(struct device_node *dn, char *name, int index)

  {

  	if (!dn || dn != of_stdout || console_set_on_cmdline)

  		return false;

  
  	/*
  	 * XXX: cast `options' to char pointer to suppress complication
  	 * warnings: printk, UART and console drivers expect char pointer.
  	 */
  	return !add_preferred_console(name, index, (char *)of_stdout_options);

  }

  EXPORT_SYMBOL_GPL(of_console_check);

  
  /**
   *	of_find_next_cache_node - Find a node's subsidiary cache
   *	@np:	node of type "cpu" or "cache"
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.  Caller should hold a reference
   *	to np.
   */
  struct device_node *of_find_next_cache_node(const struct device_node *np)
  {

  	struct device_node *child, *cache_node;

  	cache_node = of_parse_phandle(np, "l2-cache", 0);
  	if (!cache_node)
  		cache_node = of_parse_phandle(np, "next-level-cache", 0);

  	if (cache_node)
  		return cache_node;

  
  	/* OF on pmac has nodes instead of properties named "l2-cache"
  	 * beneath CPU nodes.
  	 */
  	if (!strcmp(np->type, "cpu"))
  		for_each_child_of_node(np, child)
  			if (!strcmp(child->type, "cache"))
  				return child;
  
  	return NULL;
  }

  
  /**

   * of_find_last_cache_level - Find the level at which the last cache is
   * 		present for the given logical cpu
   *
   * @cpu: cpu number(logical index) for which the last cache level is needed
   *
   * Returns the the level at which the last cache is present. It is exactly
   * same as  the total number of cache levels for the given logical cpu.
   */
  int of_find_last_cache_level(unsigned int cpu)
  {
  	u32 cache_level = 0;
  	struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
  
  	while (np) {
  		prev = np;
  		of_node_put(np);
  		np = of_find_next_cache_node(np);
  	}
  
  	of_property_read_u32(prev, "cache-level", &cache_level);
  
  	return cache_level;
  }