of: Move OF property and graph API from base.c to property.c

base.c contains both core OF functions and increasingly other
functionality such as accessing properties and graphs, including
convenience functions. In the near future this would also include OF
specific implementation of the fwnode property and graph APIs.

Create driver/of/property.c to contain procedures for accessing and
interpreting device tree properties. The procedures are moved from
drivers/of/base.c, with no changes other than copying only the includes
required by the moved procedures.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 766 insertions, 0 deletions

diff --git a/drivers/of/property.c b/drivers/of/property.c
new file mode 100644
index 000000000000..457c313a8924
--- /dev/null
+++ b/drivers/of/property.c
@@ -0,0 +1,766 @@
+/*
+ * drivers/of/property.c - Procedures for accessing and interpreting
+ *			   Devicetree properties and graphs.
+ *
+ * Initially created by copying procedures from drivers/of/base.c. This
+ * file contains the OF property as well as the OF graph interface
+ * functions.
+ *
+ * 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.
+ *
+ *      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.
+ */
+
+#define pr_fmt(fmt)	"OF: " fmt
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_graph.h>
+#include <linux/string.h>
+
+#include "of_private.h"
+
+/**
+ * of_property_count_elems_of_size - Count the number of elements in a property
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @elem_size:	size of the individual element
+ *
+ * Search for a property in a device node and count the number of elements of
+ * size elem_size in it. Returns number of elements on sucess, -EINVAL if the
+ * property does not exist or its length does not match a multiple of elem_size
+ * and -ENODATA if the property does not have a value.
+ */
+int of_property_count_elems_of_size(const struct device_node *np,
+				const char *propname, int elem_size)
+{
+	struct property *prop = of_find_property(np, propname, NULL);
+
+	if (!prop)
+		return -EINVAL;
+	if (!prop->value)
+		return -ENODATA;
+
+	if (prop->length % elem_size != 0) {
+		pr_err("size of %s in node %s is not a multiple of %d\n",
+		       propname, np->full_name, elem_size);
+		return -EINVAL;
+	}
+
+	return prop->length / elem_size;
+}
+EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);
+
+/**
+ * of_find_property_value_of_size
+ *
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @min:	minimum allowed length of property value
+ * @max:	maximum allowed length of property value (0 means unlimited)
+ * @len:	if !=NULL, actual length is written to here
+ *
+ * Search for a property in a device node and valid the requested size.
+ * Returns 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 is too small or too large.
+ *
+ */
+static void *of_find_property_value_of_size(const struct device_node *np,
+			const char *propname, u32 min, u32 max, size_t *len)
+{
+	struct property *prop = of_find_property(np, propname, NULL);
+
+	if (!prop)
+		return ERR_PTR(-EINVAL);
+	if (!prop->value)
+		return ERR_PTR(-ENODATA);
+	if (prop->length < min)
+		return ERR_PTR(-EOVERFLOW);
+	if (max && prop->length > max)
+		return ERR_PTR(-EOVERFLOW);
+
+	if (len)
+		*len = prop->length;
+
+	return prop->value;
+}
+
+/**
+ * of_property_read_u32_index - Find and read a u32 from a multi-value 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 u32 in the list of values
+ * @out_value:	pointer to return value, modified only if no error.
+ *
+ * Search for a property in a device node and read nth 32-bit value from
+ * it. Returns 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.
+ *
+ * The out_value is modified only if a valid u32 value can be decoded.
+ */
+int of_property_read_u32_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u32 *out_value)
+{
+	const u32 *val = of_find_property_value_of_size(np, propname,
+					((index + 1) * sizeof(*out_value)),
+					0,
+					NULL);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	*out_value = be32_to_cpup(((__be32 *)val) + index);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_u32_index);
+
+/**
+ * of_property_read_u64_index - Find and read a u64 from a multi-value 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 u64 in the list of values
+ * @out_value:	pointer to return value, modified only if no error.
+ *
+ * Search for a property in a device node and read nth 64-bit value from
+ * it. Returns 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.
+ *
+ * The out_value is modified only if a valid u64 value can be decoded.
+ */
+int of_property_read_u64_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u64 *out_value)
+{
+	const u64 *val = of_find_property_value_of_size(np, propname,
+					((index + 1) * sizeof(*out_value)),
+					0, NULL);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	*out_value = be64_to_cpup(((__be64 *)val) + index);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_u64_index);
+
+/**
+ * of_property_read_variable_u8_array - Find and read an array of u8 from a
+ * property, with bounds on the minimum and maximum array size.
+ *
+ * @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_min:	minimum number of array elements to read
+ * @sz_max:	maximum number of array elements to read, if zero there is no
+ *		upper limit on the number of elements in the dts entry but only
+ *		sz_min will be read.
+ *
+ * Search for a property in a device node and read 8-bit value(s) from
+ * it. Returns number of elements read on success, -EINVAL if the property
+ * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
+ * if the property data is smaller than sz_min or longer than sz_max.
+ *
+ * dts entry of array should be like:
+ *	property = /bits/ 8 <0x50 0x60 0x70>;
+ *
+ * The out_values is modified only if a valid u8 value can be decoded.
+ */
+int of_property_read_variable_u8_array(const struct device_node *np,
+					const char *propname, u8 *out_values,
+					size_t sz_min, size_t sz_max)
+{
+	size_t sz, count;
+	const u8 *val = of_find_property_value_of_size(np, propname,
+						(sz_min * sizeof(*out_values)),
+						(sz_max * sizeof(*out_values)),
+						&sz);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	if (!sz_max)
+		sz = sz_min;
+	else
+		sz /= sizeof(*out_values);
+
+	count = sz;
+	while (count--)
+		*out_values++ = *val++;
+
+	return sz;
+}
+EXPORT_SYMBOL_GPL(of_property_read_variable_u8_array);
+
+/**
+ * of_property_read_variable_u16_array - Find and read an array of u16 from a
+ * property, with bounds on the minimum and maximum array size.
+ *
+ * @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_min:	minimum number of array elements to read
+ * @sz_max:	maximum number of array elements to read, if zero there is no
+ *		upper limit on the number of elements in the dts entry but only
+ *		sz_min will be read.
+ *
+ * Search for a property in a device node and read 16-bit value(s) from
+ * it. Returns number of elements read on success, -EINVAL if the property
+ * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
+ * if the property data is smaller than sz_min or longer than sz_max.
+ *
+ * dts entry of array should be like:
+ *	property = /bits/ 16 <0x5000 0x6000 0x7000>;
+ *
+ * The out_values is modified only if a valid u16 value can be decoded.
+ */
+int of_property_read_variable_u16_array(const struct device_node *np,
+					const char *propname, u16 *out_values,
+					size_t sz_min, size_t sz_max)
+{
+	size_t sz, count;
+	const __be16 *val = of_find_property_value_of_size(np, propname,
+						(sz_min * sizeof(*out_values)),
+						(sz_max * sizeof(*out_values)),
+						&sz);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	if (!sz_max)
+		sz = sz_min;
+	else
+		sz /= sizeof(*out_values);
+
+	count = sz;
+	while (count--)
+		*out_values++ = be16_to_cpup(val++);
+
+	return sz;
+}
+EXPORT_SYMBOL_GPL(of_property_read_variable_u16_array);
+
+/**
+ * of_property_read_variable_u32_array - Find and read an array of 32 bit
+ * integers from a property, with bounds on the minimum and maximum array size.
+ *
+ * @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_min:	minimum number of array elements to read
+ * @sz_max:	maximum number of array elements to read, if zero there is no
+ *		upper limit on the number of elements in the dts entry but only
+ *		sz_min will be read.
+ *
+ * Search for a property in a device node and read 32-bit value(s) from
+ * it. Returns number of elements read on success, -EINVAL if the property
+ * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
+ * if the property data is smaller than sz_min or longer than sz_max.
+ *
+ * The out_values is modified only if a valid u32 value can be decoded.
+ */
+int of_property_read_variable_u32_array(const struct device_node *np,
+			       const char *propname, u32 *out_values,
+			       size_t sz_min, size_t sz_max)
+{
+	size_t sz, count;
+	const __be32 *val = of_find_property_value_of_size(np, propname,
+						(sz_min * sizeof(*out_values)),
+						(sz_max * sizeof(*out_values)),
+						&sz);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	if (!sz_max)
+		sz = sz_min;
+	else
+		sz /= sizeof(*out_values);
+
+	count = sz;
+	while (count--)
+		*out_values++ = be32_to_cpup(val++);
+
+	return sz;
+}
+EXPORT_SYMBOL_GPL(of_property_read_variable_u32_array);
+
+/**
+ * of_property_read_u64 - Find and read a 64 bit integer from a property
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @out_value:	pointer to return value, modified only if return value is 0.
+ *
+ * Search for a property in a device node and read a 64-bit value from
+ * it. Returns 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.
+ *
+ * The out_value is modified only if a valid u64 value can be decoded.
+ */
+int of_property_read_u64(const struct device_node *np, const char *propname,
+			 u64 *out_value)
+{
+	const __be32 *val = of_find_property_value_of_size(np, propname,
+						sizeof(*out_value),
+						0,
+						NULL);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	*out_value = of_read_number(val, 2);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_u64);
+
+/**
+ * of_property_read_variable_u64_array - Find and read an array of 64 bit
+ * integers from a property, with bounds on the minimum and maximum array size.
+ *
+ * @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_min:	minimum number of array elements to read
+ * @sz_max:	maximum number of array elements to read, if zero there is no
+ *		upper limit on the number of elements in the dts entry but only
+ *		sz_min will be read.
+ *
+ * Search for a property in a device node and read 64-bit value(s) from
+ * it. Returns number of elements read on success, -EINVAL if the property
+ * does not exist, -ENODATA if property does not have a value, and -EOVERFLOW
+ * if the property data is smaller than sz_min or longer than sz_max.
+ *
+ * The out_values is modified only if a valid u64 value can be decoded.
+ */
+int of_property_read_variable_u64_array(const struct device_node *np,
+			       const char *propname, u64 *out_values,
+			       size_t sz_min, size_t sz_max)
+{
+	size_t sz, count;
+	const __be32 *val = of_find_property_value_of_size(np, propname,
+						(sz_min * sizeof(*out_values)),
+						(sz_max * sizeof(*out_values)),
+						&sz);
+
+	if (IS_ERR(val))
+		return PTR_ERR(val);
+
+	if (!sz_max)
+		sz = sz_min;
+	else
+		sz /= sizeof(*out_values);
+
+	count = sz;
+	while (count--) {
+		*out_values++ = of_read_number(val, 2);
+		val += 2;
+	}
+
+	return sz;
+}
+EXPORT_SYMBOL_GPL(of_property_read_variable_u64_array);
+
+/**
+ * of_property_read_string - Find and read a string from a property
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ * @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). 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.
+ */
+int of_property_read_string(const struct device_node *np, const char *propname,
+				const char **out_string)
+{
+	const struct property *prop = of_find_property(np, propname, NULL);
+	if (!prop)
+		return -EINVAL;
+	if (!prop->value)
+		return -ENODATA;
+	if (strnlen(prop->value, prop->length) >= prop->length)
+		return -EILSEQ;
+	*out_string = prop->value;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_property_read_string);
+
+/**
+ * of_property_match_string() - Find string in a list and return index
+ * @np: pointer to node containing string list property
+ * @propname: string list property name
+ * @string: pointer to string to search for in string list
+ *
+ * This function searches a string list property and returns the index
+ * of a specific string value.
+ */
+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;
+		pr_debug("comparing %s with %s\n", string, p);
+		if (strcmp(string, p) == 0)
+			return i; /* Found it; return index */
+	}
+	return -ENODATA;
+}
+EXPORT_SYMBOL_GPL(of_property_match_string);
+
+/**
+ * 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;
+}
+EXPORT_SYMBOL_GPL(of_property_read_string_helper);
+
+const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
+			       u32 *pu)
+{
+	const void *curv = cur;
+
+	if (!prop)
+		return NULL;
+
+	if (!cur) {
+		curv = prop->value;
+		goto out_val;
+	}
+
+	curv += sizeof(*cur);
+	if (curv >= prop->value + prop->length)
+		return NULL;
+
+out_val:
+	*pu = be32_to_cpup(curv);
+	return curv;
+}
+EXPORT_SYMBOL_GPL(of_prop_next_u32);
+
+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;
+}
+EXPORT_SYMBOL_GPL(of_prop_next_string);
+
+/**
+ * of_graph_parse_endpoint() - parse common endpoint node properties
+ * @node: pointer to endpoint device_node
+ * @endpoint: pointer to the OF endpoint data structure
+ *
+ * The caller should hold a reference to @node.
+ */
+int of_graph_parse_endpoint(const struct device_node *node,
+			    struct of_endpoint *endpoint)
+{
+	struct device_node *port_node = of_get_parent(node);
+
+	WARN_ONCE(!port_node, "%s(): endpoint %s has no parent node\n",
+		  __func__, node->full_name);
+
+	memset(endpoint, 0, sizeof(*endpoint));
+
+	endpoint->local_node = node;
+	/*
+	 * It doesn't matter whether the two calls below succeed.
+	 * If they don't then the default value 0 is used.
+	 */
+	of_property_read_u32(port_node, "reg", &endpoint->port);
+	of_property_read_u32(node, "reg", &endpoint->id);
+
+	of_node_put(port_node);
+
+	return 0;
+}
+EXPORT_SYMBOL(of_graph_parse_endpoint);
+
+/**
+ * of_graph_get_port_by_id() - get the port matching a given id
+ * @parent: pointer to the parent device node
+ * @id: id of the port
+ *
+ * Return: A 'port' node pointer with refcount incremented. The caller
+ * has to use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_port_by_id(struct device_node *parent, u32 id)
+{
+	struct device_node *node, *port;
+
+	node = of_get_child_by_name(parent, "ports");
+	if (node)
+		parent = node;
+
+	for_each_child_of_node(parent, port) {
+		u32 port_id = 0;
+
+		if (of_node_cmp(port->name, "port") != 0)
+			continue;
+		of_property_read_u32(port, "reg", &port_id);
+		if (id == port_id)
+			break;
+	}
+
+	of_node_put(node);
+
+	return port;
+}
+EXPORT_SYMBOL(of_graph_get_port_by_id);
+
+/**
+ * of_graph_get_next_endpoint() - get next endpoint node
+ * @parent: pointer to the parent device node
+ * @prev: previous endpoint node, or NULL to get first
+ *
+ * Return: An 'endpoint' node pointer with refcount incremented. Refcount
+ * of the passed @prev node is decremented.
+ */
+struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
+					struct device_node *prev)
+{
+	struct device_node *endpoint;
+	struct device_node *port;
+
+	if (!parent)
+		return NULL;
+
+	/*
+	 * Start by locating the port node. If no previous endpoint is specified
+	 * search for the first port node, otherwise get the previous endpoint
+	 * parent port node.
+	 */
+	if (!prev) {
+		struct device_node *node;
+
+		node = of_get_child_by_name(parent, "ports");
+		if (node)
+			parent = node;
+
+		port = of_get_child_by_name(parent, "port");
+		of_node_put(node);
+
+		if (!port) {
+			pr_err("graph: no port node found in %s\n",
+			       parent->full_name);
+			return NULL;
+		}
+	} else {
+		port = of_get_parent(prev);
+		if (WARN_ONCE(!port, "%s(): endpoint %s has no parent node\n",
+			      __func__, prev->full_name))
+			return NULL;
+	}
+
+	while (1) {
+		/*
+		 * Now that we have a port node, get the next endpoint by
+		 * getting the next child. If the previous endpoint is NULL this
+		 * will return the first child.
+		 */
+		endpoint = of_get_next_child(port, prev);
+		if (endpoint) {
+			of_node_put(port);
+			return endpoint;
+		}
+
+		/* No more endpoints under this port, try the next one. */
+		prev = NULL;
+
+		do {
+			port = of_get_next_child(parent, port);
+			if (!port)
+				return NULL;
+		} while (of_node_cmp(port->name, "port"));
+	}
+}
+EXPORT_SYMBOL(of_graph_get_next_endpoint);
+
+/**
+ * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
+ * @parent: pointer to the parent device node
+ * @port_reg: identifier (value of reg property) of the parent port node
+ * @reg: identifier (value of reg property) of the endpoint node
+ *
+ * Return: An 'endpoint' node pointer which is identified by reg and at the same
+ * is the child of a port node identified by port_reg. reg and port_reg are
+ * ignored when they are -1.
+ */
+struct device_node *of_graph_get_endpoint_by_regs(
+	const struct device_node *parent, int port_reg, int reg)
+{
+	struct of_endpoint endpoint;
+	struct device_node *node = NULL;
+
+	for_each_endpoint_of_node(parent, node) {
+		of_graph_parse_endpoint(node, &endpoint);
+		if (((port_reg == -1) || (endpoint.port == port_reg)) &&
+			((reg == -1) || (endpoint.id == reg)))
+			return node;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_graph_get_endpoint_by_regs);
+
+/**
+ * of_graph_get_remote_port_parent() - get remote port's parent node
+ * @node: pointer to a local endpoint device_node
+ *
+ * Return: Remote device node associated with remote endpoint node linked
+ *	   to @node. Use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_remote_port_parent(
+			       const struct device_node *node)
+{
+	struct device_node *np;
+	unsigned int depth;
+
+	/* Get remote endpoint node. */
+	np = of_parse_phandle(node, "remote-endpoint", 0);
+
+	/* Walk 3 levels up only if there is 'ports' node. */
+	for (depth = 3; depth && np; depth--) {
+		np = of_get_next_parent(np);
+		if (depth == 2 && of_node_cmp(np->name, "ports"))
+			break;
+	}
+	return np;
+}
+EXPORT_SYMBOL(of_graph_get_remote_port_parent);
+
+/**
+ * of_graph_get_remote_port() - get remote port node
+ * @node: pointer to a local endpoint device_node
+ *
+ * Return: Remote port node associated with remote endpoint node linked
+ *	   to @node. Use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_remote_port(const struct device_node *node)
+{
+	struct device_node *np;
+
+	/* Get remote endpoint node. */
+	np = of_parse_phandle(node, "remote-endpoint", 0);
+	if (!np)
+		return NULL;
+	return of_get_next_parent(np);
+}
+EXPORT_SYMBOL(of_graph_get_remote_port);
+
+/**
+ * of_graph_get_remote_node() - get remote parent device_node for given port/endpoint
+ * @node: pointer to parent device_node containing graph port/endpoint
+ * @port: identifier (value of reg property) of the parent port node
+ * @endpoint: identifier (value of reg property) of the endpoint node
+ *
+ * Return: Remote device node associated with remote endpoint node linked
+ *	   to @node. Use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_remote_node(const struct device_node *node,
+					     u32 port, u32 endpoint)
+{
+	struct device_node *endpoint_node, *remote;
+
+	endpoint_node = of_graph_get_endpoint_by_regs(node, port, endpoint);
+	if (!endpoint_node) {
+		pr_debug("no valid endpoint (%d, %d) for node %s\n",
+			 port, endpoint, node->full_name);
+		return NULL;
+	}
+
+	remote = of_graph_get_remote_port_parent(endpoint_node);
+	of_node_put(endpoint_node);
+	if (!remote) {
+		pr_debug("no valid remote node\n");
+		return NULL;
+	}
+
+	if (!of_device_is_available(remote)) {
+		pr_debug("not available for remote node\n");
+		return NULL;
+	}
+
+	return remote;
+}
+EXPORT_SYMBOL(of_graph_get_remote_node);