dm: core: Add livetree access functions

Add a basic assortment of functions to access the live device tree. These
come from Linux v4.9 and are modified for U-Boot to the minimum extent
possible. While these functions are now very stable in Linux, it will be
possible to merge in fixes if needed.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_$(SPL_)SIMPLE_BUS)	+= simple-bus.o
 obj-$(CONFIG_DM)	+= dump.o
 obj-$(CONFIG_$(SPL_)REGMAP)	+= regmap.o
 obj-$(CONFIG_$(SPL_)SYSCON)	+= syscon-uclass.o
+obj-$(CONFIG_OF_LIVE) += of_access.o

drivers/core/of_access.c

@@ -0,0 +1,735 @@
+/*
+ * Originally from Linux v4.9
+ * 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.
+ *
+ * Modified for U-Boot
+ * Copyright (c) 2017 Google, Inc
+ *
+ * This file follows drivers/of/base.c with functions in the same order as the
+ * Linux version.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <libfdt.h>
+#include <dm/of_access.h>
+#include <linux/ctype.h>
+#include <linux/err.h>
+#include <linux/ioport.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* list of struct alias_prop aliases */
+LIST_HEAD(aliases_lookup);
+
+/* "/aliaes" node */
+static struct device_node *of_aliases;
+
+/* "/chosen" node */
+static struct device_node *of_chosen;
+
+/* node pointed to by the stdout-path alias */
+static struct device_node *of_stdout;
+
+/* pointer to options given after the alias (separated by :) or NULL if none */
+static const char *of_stdout_options;
+
+/**
+ * struct alias_prop - Alias property in 'aliases' node
+ *
+ * The structure represents one alias property of 'aliases' node as
+ * an entry in aliases_lookup list.
+ *
+ * @link:	List node to link the structure in aliases_lookup list
+ * @alias:	Alias property name
+ * @np:		Pointer to device_node that the alias stands for
+ * @id:		Index value from end of alias name
+ * @stem:	Alias string without the index
+ */
+struct alias_prop {
+	struct list_head link;
+	const char *alias;
+	struct device_node *np;
+	int id;
+	char stem[0];
+};
+
+int of_n_addr_cells(const struct device_node *np)
+{
+	const __be32 *ip;
+
+	do {
+		if (np->parent)
+			np = np->parent;
+		ip = of_get_property(np, "#address-cells", NULL);
+		if (ip)
+			return be32_to_cpup(ip);
+	} while (np->parent);
+
+	/* No #address-cells property for the root node */
+	return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
+}
+
+int of_n_size_cells(const struct device_node *np)
+{
+	const __be32 *ip;
+
+	do {
+		if (np->parent)
+			np = np->parent;
+		ip = of_get_property(np, "#size-cells", NULL);
+		if (ip)
+			return be32_to_cpup(ip);
+	} while (np->parent);
+
+	/* No #size-cells property for the root node */
+	return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
+}
+
+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 (strcmp(pp->name, name) == 0) {
+			if (lenp)
+				*lenp = pp->length;
+			break;
+		}
+	}
+	if (!pp && lenp)
+		*lenp = -FDT_ERR_NOTFOUND;
+
+	return pp;
+}
+
+struct device_node *of_find_all_nodes(struct device_node *prev)
+{
+	struct device_node *np;
+
+	if (!prev) {
+		np = gd->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;
+}
+
+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;
+}
+
+static const char *of_prop_next_string(struct property *prop, const char *cur)
+{
+	const void *curv = cur;
+
+	if (!prop)
+		return NULL;
+
+	if (!cur)
+		return prop->value;
+
+	curv += strlen(cur) + 1;
+	if (curv >= prop->value + prop->length)
+		return NULL;
+
+	return curv;
+}
+
+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;
+}
+
+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"))
+			return true;
+	}
+
+	return false;
+}
+
+struct device_node *of_get_parent(const struct device_node *node)
+{
+	const struct device_node *np;
+
+	if (!node)
+		return NULL;
+
+	np = of_node_get(node->parent);
+
+	return (struct device_node *)np;
+}
+
+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))
+
+static 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 = strrchr(child->full_name, '/');
+
+		name++;
+		if (strncmp(path, name, len) == 0 && (strlen(name) == len))
+			return child;
+	}
+	return NULL;
+}
+
+#define for_each_property_of_node(dn, pp) \
+	for (pp = dn->properties; pp != NULL; pp = pp->next)
+
+struct device_node *of_find_node_opts_by_path(const char *path,
+					      const char **opts)
+{
+	struct device_node *np = NULL;
+	struct property *pp;
+	const char *separator = strchr(path, ':');
+
+	if (opts)
+		*opts = separator ? separator + 1 : NULL;
+
+	if (strcmp(path, "/") == 0)
+		return of_node_get(gd->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 */
+	if (!np)
+		np = of_node_get(gd->of_root);
+	while (np && *path == '/') {
+		struct device_node *tmp = np;
+
+		path++; /* Increment past '/' delimiter */
+		np = __of_find_node_by_path(np, path);
+		of_node_put(tmp);
+		path = strchrnul(path, '/');
+		if (separator && separator < path)
+			break;
+	}
+
+	return np;
+}
+
+struct device_node *of_find_compatible_node(struct device_node *from,
+		const char *type, const char *compatible)
+{
+	struct device_node *np;
+
+	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);
+
+	return np;
+}
+
+struct device_node *of_find_node_by_phandle(phandle handle)
+{
+	struct device_node *np;
+
+	if (!handle)
+		return NULL;
+
+	for_each_of_allnodes(np)
+		if (np->phandle == handle)
+			break;
+	(void)of_node_get(np);
+
+	return np;
+}
+
+/**
+ * of_find_property_value_of_size() - find property of given size
+ *
+ * Search for a property in a device node and validate the requested size.
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @len:	requested length of property value
+ *
+ * @return the property value on success, -EINVAL if the property does not
+ * exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
+ * property data isn't large enough.
+ */
+static void *of_find_property_value_of_size(const struct device_node *np,
+					    const char *propname, u32 len)
+{
+	struct property *prop = of_find_property(np, propname, NULL);
+
+	if (!prop)
+		return ERR_PTR(-EINVAL);
+	if (!prop->value)
+		return ERR_PTR(-ENODATA);
+	if (len > prop->length)
+		return ERR_PTR(-EOVERFLOW);
+
+	return prop->value;
+}
+
+int of_read_u32(const struct device_node *np, const char *propname, u32 *outp)
+{
+	const __be32 *val;
+
+	debug("%s: %s: ", __func__, propname);
+	if (!np)
+		return -EINVAL;
+	val = of_find_property_value_of_size(np, propname, sizeof(*outp));
+	if (IS_ERR(val)) {
+		debug("(not found)\n");
+		return PTR_ERR(val);
+	}
+
+	*outp = be32_to_cpup(val);
+	debug("%#x (%d)\n", *outp, *outp);
+
+	return 0;
+}
+
+int of_read_u32_array(const struct device_node *np, const char *propname,
+		      u32 *out_values, size_t sz)
+{
+	const __be32 *val;
+
+	debug("%s: %s: ", __func__, propname);
+	val = of_find_property_value_of_size(np, propname,
+					     sz * sizeof(*out_values));
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	debug("size %zd\n", sz);
+	while (sz--)
+		*out_values++ = be32_to_cpup(val++);
+
+	return 0;
+}
+
+int of_property_match_string(const struct device_node *np, const char *propname,
+			     const char *string)
+{
+	const struct property *prop = of_find_property(np, propname, NULL);
+	size_t l;
+	int i;
+	const char *p, *end;
+
+	if (!prop)
+		return -EINVAL;
+	if (!prop->value)
+		return -ENODATA;
+
+	p = prop->value;
+	end = p + prop->length;
+
+	for (i = 0; p < end; i++, p += l) {
+		l = strnlen(p, end - p) + 1;
+		if (p + l > end)
+			return -EILSEQ;
+		debug("comparing %s with %s\n", string, p);
+		if (strcmp(string, p) == 0)
+			return i; /* Found it; return index */
+	}
+	return -ENODATA;
+}
+
+/**
+ * of_property_read_string_helper() - Utility helper for parsing string properties
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @out_strs:	output array of string pointers.
+ * @sz:		number of array elements to read.
+ * @skip:	Number of strings to skip over at beginning of list.
+ *
+ * Don't call this function directly. It is a utility helper for the
+ * of_property_read_string*() family of functions.
+ */
+int of_property_read_string_helper(const struct device_node *np,
+				   const char *propname, const char **out_strs,
+				   size_t sz, int skip)
+{
+	const struct property *prop = of_find_property(np, propname, NULL);
+	int l = 0, i = 0;
+	const char *p, *end;
+
+	if (!prop)
+		return -EINVAL;
+	if (!prop->value)
+		return -ENODATA;
+	p = prop->value;
+	end = p + prop->length;
+
+	for (i = 0; p < end && (!out_strs || i < skip + sz); i++, p += l) {
+		l = strnlen(p, end - p) + 1;
+		if (p + l > end)
+			return -EILSEQ;
+		if (out_strs && i >= skip)
+			*out_strs++ = p;
+	}
+	i -= skip;
+	return i <= 0 ? -ENODATA : i;
+}
+
+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)
+{
+	const __be32 *list, *list_end;
+	int rc = 0, cur_index = 0;
+	uint32_t count = 0;
+	struct device_node *node = NULL;
+	phandle phandle;
+	int size;
+
+	/* Retrieve the phandle list property */
+	list = of_get_property(np, list_name, &size);
+	if (!list)
+		return -ENOENT;
+	list_end = list + size / sizeof(*list);
+
+	/* Loop over the phandles until all the requested entry is found */
+	while (list < list_end) {
+		rc = -EINVAL;
+		count = 0;
+
+		/*
+		 * If phandle is 0, then it is an empty entry with no
+		 * arguments.  Skip forward to the next entry.
+		 */
+		phandle = be32_to_cpup(list++);
+		if (phandle) {
+			/*
+			 * Find the provider node and parse the #*-cells
+			 * property to determine the argument length.
+			 *
+			 * This is not needed if the cell count is hard-coded
+			 * (i.e. cells_name not set, but cell_count is set),
+			 * except when we're going to return the found node
+			 * below.
+			 */
+			if (cells_name || cur_index == index) {
+				node = of_find_node_by_phandle(phandle);
+				if (!node) {
+					debug("%s: could not find phandle\n",
+					      np->full_name);
+					goto err;
+				}
+			}
+
+			if (cells_name) {
+				if (of_read_u32(node, cells_name, &count)) {
+					debug("%s: could not get %s for %s\n",
+					      np->full_name, cells_name,
+					      node->full_name);
+					goto err;
+				}
+			} else {
+				count = cell_count;
+			}
+
+			/*
+			 * Make sure that the arguments actually fit in the
+			 * remaining property data length
+			 */
+			if (list + count > list_end) {
+				debug("%s: arguments longer than property\n",
+				      np->full_name);
+				goto err;
+			}
+		}
+
+		/*
+		 * All of the error cases above 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 (!phandle)
+				goto err;
+
+			if (out_args) {
+				int i;
+				if (WARN_ON(count > OF_MAX_PHANDLE_ARGS))
+					count = OF_MAX_PHANDLE_ARGS;
+				out_args->np = node;
+				out_args->args_count = count;
+				for (i = 0; i < count; i++)
+					out_args->args[i] =
+							be32_to_cpup(list++);
+			} else {
+				of_node_put(node);
+			}
+
+			/* Found it! return success */
+			return 0;
+		}
+
+		of_node_put(node);
+		node = NULL;
+		list += count;
+		cur_index++;
+	}
+
+	/*
+	 * Unlock node before returning result; will be one of:
+	 * -ENOENT : index is for empty phandle
+	 * -EINVAL : parsing error on data
+	 * [1..n]  : Number of phandle (count mode; when index = -1)
+	 */
+	rc = index < 0 ? cur_index : -ENOENT;
+ err:
+	if (node)
+		of_node_put(node);
+	return rc;
+}
+
+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;
+}
+
+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);
+}
+
+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);
+	debug("adding DT alias:%s: stem=%s id=%i node=%s\n",
+	      ap->alias, ap->stem, ap->id, of_node_full_name(np));
+}
+
+int of_alias_scan(void)
+{
+	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) {
+		const char *name;
+
+		name = of_get_property(of_chosen, "stdout-path", NULL);
+		if (name)
+			of_stdout = of_find_node_opts_by_path(name,
+							&of_stdout_options);
+	}
+
+	if (!of_aliases)
+		return 0;
+
+	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;
+		ulong id;
+		int 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 (strict_strtoul(end, 10, &id) < 0)
+			continue;
+
+		/* Allocate an alias_prop with enough space for the stem */
+		ap = malloc(sizeof(*ap) + len + 1);
+		if (!ap)
+			return -ENOMEM;
+		memset(ap, 0, sizeof(*ap) + len + 1);
+		ap->alias = start;
+		of_alias_add(ap, np, id, start, len);
+	}
+
+	return 0;
+}
+
+int of_alias_get_id(const 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;
+}
+
+struct device_node *of_get_stdout(void)
+{
+	return of_stdout;
+}

include/dm/of_access.h

@@ -0,0 +1,347 @@
+/*
+ * Originally from Linux v4.9
+ * Copyright (C) 1996-2005 Paul Mackerras.
+ *
+ * Updates for PPC64 by Peter Bergner & David Engebretsen, IBM Corp.
+ * Updates for SPARC64 by David S. Miller
+ * Derived from PowerPC and Sparc prom.h files by Stephen Rothwell, IBM Corp.
+ *
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * Modified for U-Boot
+ * Copyright (c) 2017 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _DM_OF_ACCESS_H
+#define _DM_OF_ACCESS_H
+
+#include <dm/of.h>
+
+/**
+ * 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);
+
+#define for_each_of_allnodes_from(from, dn) \
+	for (dn = of_find_all_nodes(from); dn; dn = of_find_all_nodes(dn))
+#define for_each_of_allnodes(dn) for_each_of_allnodes_from(NULL, dn)
+
+/* Dummy functions to mirror Linux. These are not used in U-Boot */
+#define of_node_get(x) (x)
+static inline void of_node_put(const struct device_node *np) { }
+
+/**
+ * of_n_addr_cells() - Get the number of address cells for a node
+ *
+ * This walks back up the tree to find the closest #address-cells property
+ * which controls the given node.
+ *
+ * @np: Node pointer to check
+ * @return number of address cells this node uses
+ */
+int of_n_addr_cells(const struct device_node *np);
+
+/**
+ * of_n_size_cells() - Get the number of size cells for a node
+ *
+ * This walks back up the tree to find the closest #size-cells property
+ * which controls the given node.
+ *
+ * @np: Node pointer to check
+ * @return number of size cells this node uses
+ */
+int of_n_size_cells(const struct device_node *np);
+
+/**
+ * of_find_property() - find a property in a node
+ *
+ * @np: Pointer to device node holding property
+ * @name: Name of property
+ * @lenp: If non-NULL, returns length of property
+ * @return pointer to property, or NULL if not found
+ */
+struct property *of_find_property(const struct device_node *np,
+				  const char *name, int *lenp);
+
+/**
+ * of_get_property() - get a property value
+ *
+ * Find a property with a given name for a given node and return the value.
+ *
+ * @np: Pointer to device node holding property
+ * @name: Name of property
+ * @lenp: If non-NULL, returns length of property
+ * @return pointer to property value, or NULL if not found
+ */
+const void *of_get_property(const struct device_node *np, const char *name,
+			    int *lenp);
+
+/**
+ * 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.
+ *
+ * @return 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
+ */
+int of_device_is_compatible(const struct device_node *np, const char *compat,
+			    const char *type, const char *name);
+
+/**
+ * of_device_is_available() - check if a device is available for use
+ *
+ * @device: Node to check for availability
+ *
+ * @return true if the status property is absent or set to "okay", false
+ * otherwise
+ */
+bool of_device_is_available(const struct device_node *np);
+
+/**
+ * of_get_parent() - Get a node's parent, if any
+ *
+ * @node: Node to check
+ * @eturns a node pointer, or NULL if none
+ */
+struct device_node *of_get_parent(const struct device_node *np);
+
+/**
+ * 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. Can be NULL
+ *
+ * Valid paths:
+ *	/foo/bar	Full path
+ *	foo		Valid alias
+ *	foo/bar		Valid alias + relative path
+ *
+ * @return a node pointer or NULL if not found
+ */
+struct device_node *of_find_node_opts_by_path(const char *path,
+					      const char **opts);
+
+static inline struct device_node *of_find_node_by_path(const char *path)
+{
+	return of_find_node_opts_by_path(path, NULL);
+}
+
+/**
+ * of_find_compatible_node() - find a node based on its compatible string
+ *
+ * Find a node based on type and one of the tokens in its "compatible" property
+ * @from: 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.
+ * @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.
+ * @return node pointer or NULL if not found
+ */
+struct device_node *of_find_compatible_node(struct device_node *from,
+				const char *type, const char *compatible);
+
+/**
+ * of_find_node_by_phandle() - Find a node given a phandle
+ *
+ * @handle:	phandle of the node to find
+ *
+ * @return node pointer, or NULL if not found
+ */
+struct device_node *of_find_node_by_phandle(phandle handle);
+
+/**
+ * of_read_u32() - Find and read a 32-bit integer from a property
+ *
+ * Search for a property in a device node and read a 32-bit value from
+ * it.
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @outp:	pointer to return value, modified only if return value is 0.
+ *
+ * @return 0 on success, -EINVAL if the property does not exist,
+ * -ENODATA if property does not have a value, and -EOVERFLOW if the
+ * property data isn't large enough.
+ */
+int of_read_u32(const struct device_node *np, const char *propname, u32 *outp);
+
+/**
+ * of_read_u32_array() - Find and read an array of 32 bit integers
+ *
+ * Search for a property in a device node and read 32-bit value(s) from
+ * it.
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @out_values:	pointer to return value, modified only if return value is 0.
+ * @sz:		number of array elements to read
+ * @return 0 on success, -EINVAL if the property does not exist, -ENODATA
+ * if property does not have a value, and -EOVERFLOW is longer than sz.
+ */
+int of_read_u32_array(const struct device_node *np, const char *propname,
+		      u32 *out_values, size_t sz);
+
+/**
+ * of_property_match_string() - Find string in a list and return index
+ *
+ * This function searches a string list property and returns the index
+ * of a specific string value.
+ *
+ * @np: pointer to node containing string list property
+ * @propname: string list property name
+ * @string: pointer to string to search for in string list
+ * @return 0 on success, -EINVAL if the property does not exist, -ENODATA
+ * if property does not have a value, and -EOVERFLOW is longer than sz.
+ */
+int of_property_match_string(const struct device_node *np, const char *propname,
+			     const char *string);
+
+int of_property_read_string_helper(const struct device_node *np,
+				   const char *propname, const char **out_strs,
+				   size_t sz, int index);
+
+/**
+ * of_property_read_string_index() - Find and read a string from a multiple
+ * strings property.
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @index:	index of the string in the list of strings
+ * @out_string:	pointer to null terminated return string, modified only if
+ *		return value is 0.
+ *
+ * Search for a property in a device tree node and retrieve a null
+ * terminated string value (pointer to data, not a copy) in the list of strings
+ * contained in that property.
+ * Returns 0 on success, -EINVAL if the property does not exist, -ENODATA if
+ * property does not have a value, and -EILSEQ if the string is not
+ * null-terminated within the length of the property data.
+ *
+ * The out_string pointer is modified only if a valid string can be decoded.
+ */
+static inline int of_property_read_string_index(const struct device_node *np,
+						const char *propname,
+						int index, const char **output)
+{
+	int rc = of_property_read_string_helper(np, propname, output, 1, index);
+	return rc < 0 ? rc : 0;
+}
+
+/**
+ * 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);
+
+/**
+ * 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)
+ * @return 0 on success (with @out_args filled out if not NULL), -ENOENT if
+ *	@list_name does not exist, -EINVAL if a phandle was not found,
+ *	@cells_name could not be found, the arguments were truncated or there
+ *	were too many arguments.
+ *
+ * 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);
+
+/**
+ * of_alias_scan() - Scan all properties of the 'aliases' node
+ *
+ * The function scans all the properties of the 'aliases' node and populates
+ * the lookup table with the properties.  It returns the number of alias
+ * properties found, or an error code in case of failure.
+ *
+ * @return 9 if OK, -ENOMEM if not enough memory
+ */
+int of_alias_scan(void);
+
+/**
+ * of_alias_get_id - Get alias id for the given device_node
+ *
+ * Travels the lookup table to get the alias id for the given device_node and
+ * alias stem.
+ *
+ * @np:		Pointer to the given device_node
+ * @stem:	Alias stem of the given device_node
+ * @return alias ID, if found, else -ENODEV
+ */
+int of_alias_get_id(const struct device_node *np, const char *stem);
+
+/**
+ * of_get_stdout() - Get node to use for stdout
+ *
+ * @return node referred to by stdout-path alias, or NULL if none
+ */
+struct device_node *of_get_stdout(void);
+
+#endif