linux/drivers/of/property.c

/*
 * 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);