/*
   * 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.
   *
   *      This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */
  #include <linux/module.h>
  #include <linux/of.h>

  #include <linux/spinlock.h>

  struct device_node *allnodes;

  /* use when traversing tree through the allnext, child, sibling,
   * or parent members of struct device_node.
   */
  DEFINE_RWLOCK(devtree_lock);

  
  int of_n_addr_cells(struct device_node *np)
  {
  	const int *ip;
  
  	do {
  		if (np->parent)
  			np = np->parent;
  		ip = of_get_property(np, "#address-cells", NULL);
  		if (ip)
  			return *ip;
  	} 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)
  {
  	const int *ip;
  
  	do {
  		if (np->parent)
  			np = np->parent;
  		ip = of_get_property(np, "#size-cells", NULL);
  		if (ip)
  			return *ip;
  	} while (np->parent);
  	/* No #size-cells property for the root node */
  	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  }
  EXPORT_SYMBOL(of_n_size_cells);

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

  	if (!np)
  		return NULL;

  	read_lock(&devtree_lock);
  	for (pp = np->properties; pp != 0; pp = pp->next) {
  		if (of_prop_cmp(pp->name, name) == 0) {
  			if (lenp != 0)
  				*lenp = pp->length;
  			break;
  		}
  	}
  	read_unlock(&devtree_lock);
  
  	return pp;
  }
  EXPORT_SYMBOL(of_find_property);

  /*
   * 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);

  
  /** 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)
  {
  	const char* cp;
  	int cplen, l;
  
  	cp = of_get_property(device, "compatible", &cplen);
  	if (cp == NULL)
  		return 0;
  	while (cplen > 0) {
  		if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
  			return 1;
  		l = strlen(cp) + 1;
  		cp += l;
  		cplen -= l;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(of_device_is_compatible);

  
  /**

   *  of_device_is_available - check if a device is available for use
   *
   *  @device: Node to check for availability
   *
   *  Returns 1 if the status property is absent or set to "okay" or "ok",
   *  0 otherwise
   */
  int of_device_is_available(const struct device_node *device)
  {
  	const char *status;
  	int statlen;
  
  	status = of_get_property(device, "status", &statlen);
  	if (status == NULL)
  		return 1;
  
  	if (statlen > 0) {
  		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
  			return 1;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(of_device_is_available);
  
  /**

   *	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;
  
  	if (!node)
  		return NULL;
  
  	read_lock(&devtree_lock);
  	np = of_node_get(node->parent);
  	read_unlock(&devtree_lock);
  	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;
  
  	if (!node)
  		return NULL;
  
  	read_lock(&devtree_lock);
  	parent = of_node_get(node->parent);
  	of_node_put(node);
  	read_unlock(&devtree_lock);
  	return parent;
  }
  
  /**

   *	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.
   */
  struct device_node *of_get_next_child(const struct device_node *node,
  	struct device_node *prev)
  {
  	struct device_node *next;
  
  	read_lock(&devtree_lock);
  	next = prev ? prev->sibling : node->child;
  	for (; next; next = next->sibling)
  		if (of_node_get(next))
  			break;
  	of_node_put(prev);
  	read_unlock(&devtree_lock);
  	return next;
  }
  EXPORT_SYMBOL(of_get_next_child);

  
  /**
   *	of_find_node_by_path - Find a node matching a full OF path
   *	@path:	The full path to match
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_node_by_path(const char *path)
  {
  	struct device_node *np = allnodes;
  
  	read_lock(&devtree_lock);
  	for (; np; np = np->allnext) {
  		if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
  		    && of_node_get(np))
  			break;
  	}
  	read_unlock(&devtree_lock);
  	return np;
  }
  EXPORT_SYMBOL(of_find_node_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 it
   *	@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;
  
  	read_lock(&devtree_lock);
  	np = from ? from->allnext : allnodes;
  	for (; np; np = np->allnext)
  		if (np->name && (of_node_cmp(np->name, name) == 0)
  		    && of_node_get(np))
  			break;
  	of_node_put(from);
  	read_unlock(&devtree_lock);
  	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;
  
  	read_lock(&devtree_lock);
  	np = from ? from->allnext : allnodes;
  	for (; np; np = np->allnext)
  		if (np->type && (of_node_cmp(np->type, type) == 0)
  		    && of_node_get(np))
  			break;
  	of_node_put(from);
  	read_unlock(&devtree_lock);
  	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;
  
  	read_lock(&devtree_lock);
  	np = from ? from->allnext : allnodes;
  	for (; np; np = np->allnext) {
  		if (type
  		    && !(np->type && (of_node_cmp(np->type, type) == 0)))
  			continue;
  		if (of_device_is_compatible(np, compatible) && of_node_get(np))
  			break;
  	}
  	of_node_put(from);
  	read_unlock(&devtree_lock);
  	return np;
  }
  EXPORT_SYMBOL(of_find_compatible_node);

  
  /**
   * of_match_node - Tell if an 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)
  {
  	while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
  		int match = 1;
  		if (matches->name[0])
  			match &= node->name
  				&& !strcmp(matches->name, node->name);
  		if (matches->type[0])
  			match &= node->type
  				&& !strcmp(matches->type, node->type);
  		if (matches->compatible[0])
  			match &= of_device_is_compatible(node,
  						matches->compatible);
  		if (match)
  			return matches;
  		matches++;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL(of_match_node);
  
  /**
   *	of_find_matching_node - 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
   *
   *	Returns a node pointer with refcount incremented, use
   *	of_node_put() on it when done.
   */
  struct device_node *of_find_matching_node(struct device_node *from,
  					  const struct of_device_id *matches)
  {
  	struct device_node *np;
  
  	read_lock(&devtree_lock);
  	np = from ? from->allnext : allnodes;
  	for (; np; np = np->allnext) {
  		if (of_match_node(matches, np) && of_node_get(np))
  			break;
  	}
  	of_node_put(from);
  	read_unlock(&devtree_lock);
  	return np;
  }
  EXPORT_SYMBOL(of_find_matching_node);