drivers/base/property.c

/*
 * property.c - Unified device property interface.
 *
 * Copyright (C) 2014, Intel Corporation
 * Authors: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 *          Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/property.h>
#include <linux/etherdevice.h>
#include <linux/phy.h>

/**
 * device_add_property_set - Add a collection of properties to a device object.
 * @dev: Device to add properties to.
 * @pset: Collection of properties to add.
 *
 * Associate a collection of device properties represented by @pset with @dev
 * as its secondary firmware node.
 */
void device_add_property_set(struct device *dev, struct property_set *pset)
{
	if (!pset)
		return;

	pset->fwnode.type = FWNODE_PDATA;
	set_secondary_fwnode(dev, &pset->fwnode);
}
EXPORT_SYMBOL_GPL(device_add_property_set);

static inline bool is_pset_node(struct fwnode_handle *fwnode)
{
	return fwnode && fwnode->type == FWNODE_PDATA;
}

static inline struct property_set *to_pset_node(struct fwnode_handle *fwnode)
{
	return is_pset_node(fwnode) ?
		container_of(fwnode, struct property_set, fwnode) : NULL;
}

static struct property_entry *pset_prop_get(struct property_set *pset,
					    const char *name)
{
	struct property_entry *prop;

	if (!pset || !pset->properties)
		return NULL;

	for (prop = pset->properties; prop->name; prop++)
		if (!strcmp(name, prop->name))
			return prop;

	return NULL;
}

static void *pset_prop_find(struct property_set *pset, const char *propname,
			    size_t length)
{
	struct property_entry *prop;
	void *pointer;

	prop = pset_prop_get(pset, propname);
	if (!prop)
		return ERR_PTR(-EINVAL);
	pointer = prop->value.raw_data;
	if (!pointer)
		return ERR_PTR(-ENODATA);
	if (length > prop->length)
		return ERR_PTR(-EOVERFLOW);
	return pointer;
}

static int pset_prop_read_u8_array(struct property_set *pset,
				   const char *propname,
				   u8 *values, size_t nval)
{
	void *pointer;
	size_t length = nval * sizeof(*values);

	pointer = pset_prop_find(pset, propname, length);
	if (IS_ERR(pointer))
		return PTR_ERR(pointer);

	memcpy(values, pointer, length);
	return 0;
}

static int pset_prop_read_u16_array(struct property_set *pset,
				    const char *propname,
				    u16 *values, size_t nval)
{
	void *pointer;
	size_t length = nval * sizeof(*values);

	pointer = pset_prop_find(pset, propname, length);
	if (IS_ERR(pointer))
		return PTR_ERR(pointer);

	memcpy(values, pointer, length);
	return 0;
}

static int pset_prop_read_u32_array(struct property_set *pset,
				    const char *propname,
				    u32 *values, size_t nval)
{
	void *pointer;
	size_t length = nval * sizeof(*values);

	pointer = pset_prop_find(pset, propname, length);
	if (IS_ERR(pointer))
		return PTR_ERR(pointer);

	memcpy(values, pointer, length);
	return 0;
}

static int pset_prop_read_u64_array(struct property_set *pset,
				    const char *propname,
				    u64 *values, size_t nval)
{
	void *pointer;
	size_t length = nval * sizeof(*values);

	pointer = pset_prop_find(pset, propname, length);
	if (IS_ERR(pointer))
		return PTR_ERR(pointer);

	memcpy(values, pointer, length);
	return 0;
}

static int pset_prop_count_elems_of_size(struct property_set *pset,
					 const char *propname, size_t length)
{
	struct property_entry *prop;

	prop = pset_prop_get(pset, propname);
	if (!prop)
		return -EINVAL;

	return prop->length / length;
}

static int pset_prop_read_string_array(struct property_set *pset,
				       const char *propname,
				       const char **strings, size_t nval)
{
	void *pointer;
	size_t length = nval * sizeof(*strings);

	pointer = pset_prop_find(pset, propname, length);
	if (IS_ERR(pointer))
		return PTR_ERR(pointer);

	memcpy(strings, pointer, length);
	return 0;
}

static inline struct fwnode_handle *dev_fwnode(struct device *dev)
{
	return IS_ENABLED(CONFIG_OF) && dev->of_node ?
		&dev->of_node->fwnode : dev->fwnode;
}

/**
 * device_property_present - check if a property of a device is present
 * @dev: Device whose property is being checked
 * @propname: Name of the property
 *
 * Check if property @propname is present in the device firmware description.
 */
bool device_property_present(struct device *dev, const char *propname)
{
	return fwnode_property_present(dev_fwnode(dev), propname);
}
EXPORT_SYMBOL_GPL(device_property_present);

/**
 * fwnode_property_present - check if a property of a firmware node is present
 * @fwnode: Firmware node whose property to check
 * @propname: Name of the property
 */
bool fwnode_property_present(struct fwnode_handle *fwnode, const char *propname)
{
	if (is_of_node(fwnode))
		return of_property_read_bool(to_of_node(fwnode), propname);
	else if (is_acpi_node(fwnode))
		return !acpi_node_prop_get(fwnode, propname, NULL);
	else if (is_pset_node(fwnode))
		return !!pset_prop_get(to_pset_node(fwnode), propname);
	return false;
}
EXPORT_SYMBOL_GPL(fwnode_property_present);

/**
 * device_property_read_u8_array - return a u8 array property of a device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Function reads an array of u8 properties with @propname from the device
 * firmware description and stores them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_u8_array(struct device *dev, const char *propname,
				  u8 *val, size_t nval)
{
	return fwnode_property_read_u8_array(dev_fwnode(dev), propname, val, nval);
}
EXPORT_SYMBOL_GPL(device_property_read_u8_array);

/**
 * device_property_read_u16_array - return a u16 array property of a device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Function reads an array of u16 properties with @propname from the device
 * firmware description and stores them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_u16_array(struct device *dev, const char *propname,
				   u16 *val, size_t nval)
{
	return fwnode_property_read_u16_array(dev_fwnode(dev), propname, val, nval);
}
EXPORT_SYMBOL_GPL(device_property_read_u16_array);

/**
 * device_property_read_u32_array - return a u32 array property of a device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Function reads an array of u32 properties with @propname from the device
 * firmware description and stores them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_u32_array(struct device *dev, const char *propname,
				   u32 *val, size_t nval)
{
	return fwnode_property_read_u32_array(dev_fwnode(dev), propname, val, nval);
}
EXPORT_SYMBOL_GPL(device_property_read_u32_array);

/**
 * device_property_read_u64_array - return a u64 array property of a device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Function reads an array of u64 properties with @propname from the device
 * firmware description and stores them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_u64_array(struct device *dev, const char *propname,
				   u64 *val, size_t nval)
{
	return fwnode_property_read_u64_array(dev_fwnode(dev), propname, val, nval);
}
EXPORT_SYMBOL_GPL(device_property_read_u64_array);

/**
 * device_property_read_string_array - return a string array property of device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Function reads an array of string properties with @propname from the device
 * firmware description and stores them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO or %-EILSEQ if the property is not an array of strings,
 *	   %-EOVERFLOW if the size of the property is not as expected.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_string_array(struct device *dev, const char *propname,
				      const char **val, size_t nval)
{
	return fwnode_property_read_string_array(dev_fwnode(dev), propname, val, nval);
}
EXPORT_SYMBOL_GPL(device_property_read_string_array);

/**
 * device_property_read_string - return a string property of a device
 * @dev: Device to get the property of
 * @propname: Name of the property
 * @val: The value is stored here
 *
 * Function reads property @propname from the device firmware description and
 * stores the value into @val if found. The value is checked to be a string.
 *
 * Return: %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO or %-EILSEQ if the property type is not a string.
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_read_string(struct device *dev, const char *propname,
				const char **val)
{
	return fwnode_property_read_string(dev_fwnode(dev), propname, val);
}
EXPORT_SYMBOL_GPL(device_property_read_string);

/**
 * device_property_match_string - find a string in an array and return index
 * @dev: Device to get the property of
 * @propname: Name of the property holding the array
 * @string: String to look for
 *
 * Find a given string in a string array and if it is found return the
 * index back.
 *
 * Return: %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of strings,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int device_property_match_string(struct device *dev, const char *propname,
				 const char *string)
{
	return fwnode_property_match_string(dev_fwnode(dev), propname, string);
}
EXPORT_SYMBOL_GPL(device_property_match_string);

#define OF_DEV_PROP_READ_ARRAY(node, propname, type, val, nval) \
	(val) ? of_property_read_##type##_array((node), (propname), (val), (nval)) \
	      : of_property_count_elems_of_size((node), (propname), sizeof(type))

#define PSET_PROP_READ_ARRAY(node, propname, type, val, nval)				\
	(val) ? pset_prop_read_##type##_array((node), (propname), (val), (nval))	\
	      : pset_prop_count_elems_of_size((node), (propname), sizeof(type))

#define FWNODE_PROP_READ_ARRAY(_fwnode_, _propname_, _type_, _proptype_, _val_, _nval_) \
({ \
	int _ret_; \
	if (is_of_node(_fwnode_)) \
		_ret_ = OF_DEV_PROP_READ_ARRAY(to_of_node(_fwnode_), _propname_, \
					       _type_, _val_, _nval_); \
	else if (is_acpi_node(_fwnode_)) \
		_ret_ = acpi_node_prop_read(_fwnode_, _propname_, _proptype_, \
					    _val_, _nval_); \
	else if (is_pset_node(_fwnode_)) 						\
		_ret_ = PSET_PROP_READ_ARRAY(to_pset_node(_fwnode_), _propname_,	\
					     _type_, _val_, _nval_);			\
	else \
		_ret_ = -ENXIO; \
	_ret_; \
})

/**
 * fwnode_property_read_u8_array - return a u8 array property of firmware node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Read an array of u8 properties with @propname from @fwnode and stores them to
 * @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_u8_array(struct fwnode_handle *fwnode,
				  const char *propname, u8 *val, size_t nval)
{
	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u8, DEV_PROP_U8,
				      val, nval);
}
EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);

/**
 * fwnode_property_read_u16_array - return a u16 array property of firmware node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Read an array of u16 properties with @propname from @fwnode and store them to
 * @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_u16_array(struct fwnode_handle *fwnode,
				   const char *propname, u16 *val, size_t nval)
{
	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u16, DEV_PROP_U16,
				      val, nval);
}
EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);

/**
 * fwnode_property_read_u32_array - return a u32 array property of firmware node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Read an array of u32 properties with @propname from @fwnode store them to
 * @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_u32_array(struct fwnode_handle *fwnode,
				   const char *propname, u32 *val, size_t nval)
{
	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u32, DEV_PROP_U32,
				      val, nval);
}
EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);

/**
 * fwnode_property_read_u64_array - return a u64 array property firmware node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Read an array of u64 properties with @propname from @fwnode and store them to
 * @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of numbers,
 *	   %-EOVERFLOW if the size of the property is not as expected,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_u64_array(struct fwnode_handle *fwnode,
				   const char *propname, u64 *val, size_t nval)
{
	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u64, DEV_PROP_U64,
				      val, nval);
}
EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);

/**
 * fwnode_property_read_string_array - return string array property of a node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The values are stored here or %NULL to return the number of values
 * @nval: Size of the @val array
 *
 * Read an string list property @propname from the given firmware node and store
 * them to @val if found.
 *
 * Return: number of values if @val was %NULL,
 *         %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of strings,
 *	   %-EOVERFLOW if the size of the property is not as expected,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_string_array(struct fwnode_handle *fwnode,
				      const char *propname, const char **val,
				      size_t nval)
{
	if (is_of_node(fwnode))
		return val ?
			of_property_read_string_array(to_of_node(fwnode),
						      propname, val, nval) :
			of_property_count_strings(to_of_node(fwnode), propname);
	else if (is_acpi_node(fwnode))
		return acpi_node_prop_read(fwnode, propname, DEV_PROP_STRING,
					   val, nval);
	else if (is_pset_node(fwnode))
		return val ?
			pset_prop_read_string_array(to_pset_node(fwnode),
						    propname, val, nval) :
			pset_prop_count_elems_of_size(to_pset_node(fwnode),
						      propname,
						      sizeof(const char *));
	return -ENXIO;
}
EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);

/**
 * fwnode_property_read_string - return a string property of a firmware node
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property
 * @val: The value is stored here
 *
 * Read property @propname from the given firmware node and store the value into
 * @val if found.  The value is checked to be a string.
 *
 * Return: %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO or %-EILSEQ if the property is not a string,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_read_string(struct fwnode_handle *fwnode,
				const char *propname, const char **val)
{
	if (is_of_node(fwnode))
		return of_property_read_string(to_of_node(fwnode), propname, val);
	else if (is_acpi_node(fwnode))
		return acpi_node_prop_read(fwnode, propname, DEV_PROP_STRING,
					   val, 1);
	else if (is_pset_node(fwnode))
		return pset_prop_read_string_array(to_pset_node(fwnode),
						   propname, val, 1);
	return -ENXIO;
}
EXPORT_SYMBOL_GPL(fwnode_property_read_string);

/**
 * fwnode_property_match_string - find a string in an array and return index
 * @fwnode: Firmware node to get the property of
 * @propname: Name of the property holding the array
 * @string: String to look for
 *
 * Find a given string in a string array and if it is found return the
 * index back.
 *
 * Return: %0 if the property was found (success),
 *	   %-EINVAL if given arguments are not valid,
 *	   %-ENODATA if the property does not have a value,
 *	   %-EPROTO if the property is not an array of strings,
 *	   %-ENXIO if no suitable firmware interface is present.
 */
int fwnode_property_match_string(struct fwnode_handle *fwnode,
	const char *propname, const char *string)
{
	const char **values;
	int nval, ret, i;

	nval = fwnode_property_read_string_array(fwnode, propname, NULL, 0);
	if (nval < 0)
		return nval;

	values = kcalloc(nval, sizeof(*values), GFP_KERNEL);
	if (!values)
		return -ENOMEM;

	ret = fwnode_property_read_string_array(fwnode, propname, values, nval);
	if (ret < 0)
		goto out;

	ret = -ENODATA;
	for (i = 0; i < nval; i++) {
		if (!strcmp(values[i], string)) {
			ret = i;
			break;
		}
	}
out:
	kfree(values);
	return ret;
}
EXPORT_SYMBOL_GPL(fwnode_property_match_string);

/**
 * device_get_next_child_node - Return the next child node handle for a device
 * @dev: Device to find the next child node for.
 * @child: Handle to one of the device's child nodes or a null handle.
 */
struct fwnode_handle *device_get_next_child_node(struct device *dev,
						 struct fwnode_handle *child)
{
	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
		struct device_node *node;

		node = of_get_next_available_child(dev->of_node, to_of_node(child));
		if (node)
			return &node->fwnode;
	} else if (IS_ENABLED(CONFIG_ACPI)) {
		return acpi_get_next_subnode(dev, child);
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(device_get_next_child_node);

/**
 * fwnode_handle_put - Drop reference to a device node
 * @fwnode: Pointer to the device node to drop the reference to.
 *
 * This has to be used when terminating device_for_each_child_node() iteration
 * with break or return to prevent stale device node references from being left
 * behind.
 */
void fwnode_handle_put(struct fwnode_handle *fwnode)
{
	if (is_of_node(fwnode))
		of_node_put(to_of_node(fwnode));
}
EXPORT_SYMBOL_GPL(fwnode_handle_put);

/**
 * device_get_child_node_count - return the number of child nodes for device
 * @dev: Device to cound the child nodes for
 */
unsigned int device_get_child_node_count(struct device *dev)
{
	struct fwnode_handle *child;
	unsigned int count = 0;

	device_for_each_child_node(dev, child)
		count++;

	return count;
}
EXPORT_SYMBOL_GPL(device_get_child_node_count);

bool device_dma_supported(struct device *dev)
{
	/* For DT, this is always supported.
	 * For ACPI, this depends on CCA, which
	 * is determined by the acpi_dma_supported().
	 */
	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
		return true;

	return acpi_dma_supported(ACPI_COMPANION(dev));
}
EXPORT_SYMBOL_GPL(device_dma_supported);

enum dev_dma_attr device_get_dma_attr(struct device *dev)
{
	enum dev_dma_attr attr = DEV_DMA_NOT_SUPPORTED;

	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
		if (of_dma_is_coherent(dev->of_node))
			attr = DEV_DMA_COHERENT;
		else
			attr = DEV_DMA_NON_COHERENT;
	} else
		attr = acpi_get_dma_attr(ACPI_COMPANION(dev));

	return attr;
}
EXPORT_SYMBOL_GPL(device_get_dma_attr);

/**
 * device_get_phy_mode - Get phy mode for given device
 * @dev:	Pointer to the given device
 *
 * The function gets phy interface string from property 'phy-mode' or
 * 'phy-connection-type', and return its index in phy_modes table, or errno in
 * error case.
 */
int device_get_phy_mode(struct device *dev)
{
	const char *pm;
	int err, i;

	err = device_property_read_string(dev, "phy-mode", &pm);
	if (err < 0)
		err = device_property_read_string(dev,
						  "phy-connection-type", &pm);
	if (err < 0)
		return err;

	for (i = 0; i < PHY_INTERFACE_MODE_MAX; i++)
		if (!strcasecmp(pm, phy_modes(i)))
			return i;

	return -ENODEV;
}
EXPORT_SYMBOL_GPL(device_get_phy_mode);

static void *device_get_mac_addr(struct device *dev,
				 const char *name, char *addr,
				 int alen)
{
	int ret = device_property_read_u8_array(dev, name, addr, alen);

	if (ret == 0 && alen == ETH_ALEN && is_valid_ether_addr(addr))
		return addr;
	return NULL;
}

/**
 * device_get_mac_address - Get the MAC for a given device
 * @dev:	Pointer to the device
 * @addr:	Address of buffer to store the MAC in
 * @alen:	Length of the buffer pointed to by addr, should be ETH_ALEN
 *
 * Search the firmware node for the best MAC address to use.  'mac-address' is
 * checked first, because that is supposed to contain to "most recent" MAC
 * address. If that isn't set, then 'local-mac-address' is checked next,
 * because that is the default address.  If that isn't set, then the obsolete
 * 'address' is checked, just in case we're using an old device tree.
 *
 * Note that the 'address' property is supposed to contain a virtual address of
 * the register set, but some DTS files have redefined that property to be the
 * MAC address.
 *
 * All-zero MAC addresses are rejected, because those could be properties that
 * exist in the firmware tables, but were not updated by the firmware.  For
 * example, the DTS could define 'mac-address' and 'local-mac-address', with
 * zero MAC addresses.  Some older U-Boots only initialized 'local-mac-address'.
 * In this case, the real MAC is in 'local-mac-address', and 'mac-address'
 * exists but is all zeros.
*/
void *device_get_mac_address(struct device *dev, char *addr, int alen)
{
	char *res;

	res = device_get_mac_addr(dev, "mac-address", addr, alen);
	if (res)
		return res;

	res = device_get_mac_addr(dev, "local-mac-address", addr, alen);
	if (res)
		return res;

	return device_get_mac_addr(dev, "address", addr, alen);
}
EXPORT_SYMBOL(device_get_mac_address);