/*
* Procedures for creating, accessing and interpreting the device tree.
*
* Paul Mackerras August 1996.
* Copyright (C) 1996-2005 Paul Mackerras.
*
* Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
* {engebret|bergner}@us.ibm.com
*
* Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
*
* Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
struct device_node *allnodes;
/* use when traversing tree through the allnext, child, sibling,
* or parent members of struct device_node.
*/
DEFINE_RWLOCK(devtree_lock);
int of_n_addr_cells(struct device_node *np)
{
const int *ip;
do {
if (np->parent)
np = np->parent;
ip = of_get_property(np, "#address-cells", NULL);
if (ip)
return *ip;
} while (np->parent);
/* No #address-cells property for the root node */
return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_addr_cells);
int of_n_size_cells(struct device_node *np)
{
const int *ip;
do {
if (np->parent)
np = np->parent;
ip = of_get_property(np, "#size-cells", NULL);
if (ip)
return *ip;
} while (np->parent);
/* No #size-cells property for the root node */
return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
}
EXPORT_SYMBOL(of_n_size_cells);
struct property *of_find_property(const struct device_node *np,
const char *name,
int *lenp)
{
struct property *pp;
if (!np)
return NULL;
read_lock(&devtree_lock);
for (pp = np->properties; pp != 0; pp = pp->next) {
if (of_prop_cmp(pp->name, name) == 0) {
if (lenp != 0)
*lenp = pp->length;
break;
}
}
read_unlock(&devtree_lock);
return pp;
}
EXPORT_SYMBOL(of_find_property);
/*
* Find a property with a given name for a given node
* and return the value.
*/
const void *of_get_property(const struct device_node *np, const char *name,
int *lenp)
{
struct property *pp = of_find_property(np, name, lenp);
return pp ? pp->value : NULL;
}
EXPORT_SYMBOL(of_get_property);
/** Checks if the given "compat" string matches one of the strings in
* the device's "compatible" property
*/
int of_device_is_compatible(const struct device_node *device,
const char *compat)
{
const char* cp;
int cplen, l;
cp = of_get_property(device, "compatible", &cplen);
if (cp == NULL)
return 0;
while (cplen > 0) {
if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
return 1;
l = strlen(cp) + 1;
cp += l;
cplen -= l;
}
return 0;
}
EXPORT_SYMBOL(of_device_is_compatible);
/**
* of_device_is_available - check if a device is available for use
*
* @device: Node to check for availability
*
* Returns 1 if the status property is absent or set to "okay" or "ok",
* 0 otherwise
*/
int of_device_is_available(const struct device_node *device)
{
const char *status;
int statlen;
status = of_get_property(device, "status", &statlen);
if (status == NULL)
return 1;
if (statlen > 0) {
if (!strcmp(status, "okay") || !strcmp(status, "ok"))
return 1;
}
return 0;
}
EXPORT_SYMBOL(of_device_is_available);
/**
* of_get_parent - Get a node's parent if any
* @node: Node to get parent
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_get_parent(const struct device_node *node)
{
struct device_node *np;
if (!node)
return NULL;
read_lock(&devtree_lock);
np = of_node_get(node->parent);
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_get_parent);
/**
* of_get_next_parent - Iterate to a node's parent
* @node: Node to get parent of
*
* This is like of_get_parent() except that it drops the
* refcount on the passed node, making it suitable for iterating
* through a node's parents.
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_get_next_parent(struct device_node *node)
{
struct device_node *parent;
if (!node)
return NULL;
read_lock(&devtree_lock);
parent = of_node_get(node->parent);
of_node_put(node);
read_unlock(&devtree_lock);
return parent;
}
/**
* of_get_next_child - Iterate a node childs
* @node: parent node
* @prev: previous child of the parent node, or NULL to get first
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_get_next_child(const struct device_node *node,
struct device_node *prev)
{
struct device_node *next;
read_lock(&devtree_lock);
next = prev ? prev->sibling : node->child;
for (; next; next = next->sibling)
if (of_node_get(next))
break;
of_node_put(prev);
read_unlock(&devtree_lock);
return next;
}
EXPORT_SYMBOL(of_get_next_child);
/**
* of_find_node_by_path - Find a node matching a full OF path
* @path: The full path to match
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_find_node_by_path(const char *path)
{
struct device_node *np = allnodes;
read_lock(&devtree_lock);
for (; np; np = np->allnext) {
if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
&& of_node_get(np))
break;
}
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_find_node_by_path);
/**
* of_find_node_by_name - Find a node by its "name" property
* @from: The node to start searching from or NULL, the node
* you pass will not be searched, only the next one
* will; typically, you pass what the previous call
* returned. of_node_put() will be called on it
* @name: The name string to match against
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_find_node_by_name(struct device_node *from,
const char *name)
{
struct device_node *np;
read_lock(&devtree_lock);
np = from ? from->allnext : allnodes;
for (; np; np = np->allnext)
if (np->name && (of_node_cmp(np->name, name) == 0)
&& of_node_get(np))
break;
of_node_put(from);
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_find_node_by_name);
/**
* of_find_node_by_type - Find a node by its "device_type" property
* @from: The node to start searching from, or NULL to start searching
* the entire device tree. The node you pass will not be
* searched, only the next one will; typically, you pass
* what the previous call returned. of_node_put() will be
* called on from for you.
* @type: The type string to match against
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_find_node_by_type(struct device_node *from,
const char *type)
{
struct device_node *np;
read_lock(&devtree_lock);
np = from ? from->allnext : allnodes;
for (; np; np = np->allnext)
if (np->type && (of_node_cmp(np->type, type) == 0)
&& of_node_get(np))
break;
of_node_put(from);
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_find_node_by_type);
/**
* of_find_compatible_node - Find a node based on type and one of the
* tokens in its "compatible" property
* @from: The node to start searching from or NULL, the node
* you pass will not be searched, only the next one
* will; typically, you pass what the previous call
* returned. of_node_put() will be called on it
* @type: The type string to match "device_type" or NULL to ignore
* @compatible: The string to match to one of the tokens in the device
* "compatible" list.
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_find_compatible_node(struct device_node *from,
const char *type, const char *compatible)
{
struct device_node *np;
read_lock(&devtree_lock);
np = from ? from->allnext : allnodes;
for (; np; np = np->allnext) {
if (type
&& !(np->type && (of_node_cmp(np->type, type) == 0)))
continue;
if (of_device_is_compatible(np, compatible) && of_node_get(np))
break;
}
of_node_put(from);
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_find_compatible_node);
/**
* of_match_node - Tell if an device_node has a matching of_match structure
* @matches: array of of device match structures to search in
* @node: the of device structure to match against
*
* Low level utility function used by device matching.
*/
const struct of_device_id *of_match_node(const struct of_device_id *matches,
const struct device_node *node)
{
while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
int match = 1;
if (matches->name[0])
match &= node->name
&& !strcmp(matches->name, node->name);
if (matches->type[0])
match &= node->type
&& !strcmp(matches->type, node->type);
if (matches->compatible[0])
match &= of_device_is_compatible(node,
matches->compatible);
if (match)
return matches;
matches++;
}
return NULL;
}
EXPORT_SYMBOL(of_match_node);
/**
* of_find_matching_node - Find a node based on an of_device_id match
* table.
* @from: The node to start searching from or NULL, the node
* you pass will not be searched, only the next one
* will; typically, you pass what the previous call
* returned. of_node_put() will be called on it
* @matches: array of of device match structures to search in
*
* Returns a node pointer with refcount incremented, use
* of_node_put() on it when done.
*/
struct device_node *of_find_matching_node(struct device_node *from,
const struct of_device_id *matches)
{
struct device_node *np;
read_lock(&devtree_lock);
np = from ? from->allnext : allnodes;
for (; np; np = np->allnext) {
if (of_match_node(matches, np) && of_node_get(np))
break;
}
of_node_put(from);
read_unlock(&devtree_lock);
return np;
}
EXPORT_SYMBOL(of_find_matching_node);
/**
* of_modalias_table: Table of explicit compatible ==> modalias mappings
*
* This table allows particulare compatible property values to be mapped
* to modalias strings. This is useful for busses which do not directly
* understand the OF device tree but are populated based on data contained
* within the device tree. SPI and I2C are the two current users of this
* table.
*
* In most cases, devices do not need to be listed in this table because
* the modalias value can be derived directly from the compatible table.
* However, if for any reason a value cannot be derived, then this table
* provides a method to override the implicit derivation.
*
* At the moment, a single table is used for all bus types because it is
* assumed that the data size is small and that the compatible values
* should already be distinct enough to differentiate between SPI, I2C
* and other devices.
*/
struct of_modalias_table {
char *of_device;
char *modalias;
};
static struct of_modalias_table of_modalias_table[] = {
/* Empty for now; add entries as needed */
};
/**
* of_modalias_node - Lookup appropriate modalias for a device node
* @node: pointer to a device tree node
* @modalias: Pointer to buffer that modalias value will be copied into
* @len: Length of modalias value
*
* Based on the value of the compatible property, this routine will determine
* an appropriate modalias value for a particular device tree node. Three
* separate methods are used to derive a modalias value.
*
* First method is to lookup the compatible value in of_modalias_table.
* Second is to look for a "linux,<modalias>" entry in the compatible list
* and used that for modalias. Third is to strip off the manufacturer
* prefix from the first compatible entry and use the remainder as modalias
*
* This routine returns 0 on success
*/
int of_modalias_node(struct device_node *node, char *modalias, int len)
{
int i, cplen;
const char *compatible;
const char *p;
/* 1. search for exception list entry */
for (i = 0; i < ARRAY_SIZE(of_modalias_table); i++) {
compatible = of_modalias_table[i].of_device;
if (!of_device_is_compatible(node, compatible))
continue;
strlcpy(modalias, of_modalias_table[i].modalias, len);
return 0;
}
compatible = of_get_property(node, "compatible", &cplen);
if (!compatible)
return -ENODEV;
/* 2. search for linux,<modalias> entry */
p = compatible;
while (cplen > 0) {
if (!strncmp(p, "linux,", 6)) {
p += 6;
strlcpy(modalias, p, len);
return 0;
}
i = strlen(p) + 1;
p += i;
cplen -= i;
}
/* 3. take first compatible entry and strip manufacturer */
p = strchr(compatible, ',');
if (!p)
return -ENODEV;
p++;
strlcpy(modalias, p, len);
return 0;
}
EXPORT_SYMBOL_GPL(of_modalias_node);
