On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:

[mmotm.git] / drivers / of / base.c

/*
 * 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_find_node_with_property - Find a node which has a property with
 *                                   the given name.
 *      @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
 *      @prop_name:     The name of the property to look for.
 *
 *      Returns a node pointer with refcount incremented, use
 *      of_node_put() on it when done.
 */
struct device_node *of_find_node_with_property(struct device_node *from,
        const char *prop_name)
{
        struct device_node *np;
        struct property *pp;

        read_lock(&devtree_lock);
        np = from ? from->allnext : allnodes;
        for (; np; np = np->allnext) {
                for (pp = np->properties; pp != 0; pp = pp->next) {
                        if (of_prop_cmp(pp->name, prop_name) == 0) {
                                of_node_get(np);
                                goto out;
                        }
                }
        }
out:
        of_node_put(from);
        read_unlock(&devtree_lock);
        return np;
}
EXPORT_SYMBOL(of_find_node_with_property);

/**
 * 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[] = {
        { "fsl,mcu-mpc8349emitx", "mcu-mpc8349emitx" },
        { "mmc-spi-slot", "mmc_spi" },
};

/**
 * 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.  Two
 * separate methods are attempted to derive a modalias value.
 *
 * First method is to lookup the compatible value in of_modalias_table.
 * Second 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. 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);

/**
 * 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(struct device_node *np, const char *phandle_name, int index)
{
        const phandle *phandle;
        int size;

        phandle = of_get_property(np, phandle_name, &size);
        if ((!phandle) || (size < sizeof(*phandle) * (index + 1)))
                return NULL;

        return of_find_node_by_phandle(phandle[index]);
}
EXPORT_SYMBOL(of_parse_phandle);

/**
 * of_parse_phandles_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_node:   optional pointer to device_node struct pointer (will be filled)
 * @out_args:   optional pointer to arguments pointer (will be filled)
 *
 * This function is useful to parse lists of phandles and their arguments.
 * Returns 0 on success and fills out_node and out_args, on error returns
 * appropriate errno value.
 *
 * 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_phandles_with_args(node3, "list", "#list-cells", 2, &node2, &args);
 */
int of_parse_phandles_with_args(struct device_node *np, const char *list_name,
                                const char *cells_name, int index,
                                struct device_node **out_node,
                                const void **out_args)
{
        int ret = -EINVAL;
        const u32 *list;
        const u32 *list_end;
        int size;
        int cur_index = 0;
        struct device_node *node = NULL;
        const void *args = NULL;

        list = of_get_property(np, list_name, &size);
        if (!list) {
                ret = -ENOENT;
                goto err0;
        }
        list_end = list + size / sizeof(*list);

        while (list < list_end) {
                const u32 *cells;
                const phandle *phandle;

                phandle = list++;
                args = list;

                /* one cell hole in the list = <>; */
                if (!*phandle)
                        goto next;

                node = of_find_node_by_phandle(*phandle);
                if (!node) {
                        pr_debug("%s: could not find phandle\n",
                                 np->full_name);
                        goto err0;
                }

                cells = of_get_property(node, cells_name, &size);
                if (!cells || size != sizeof(*cells)) {
                        pr_debug("%s: could not get %s for %s\n",
                                 np->full_name, cells_name, node->full_name);
                        goto err1;
                }

                list += *cells;
                if (list > list_end) {
                        pr_debug("%s: insufficient arguments length\n",
                                 np->full_name);
                        goto err1;
                }
next:
                if (cur_index == index)
                        break;

                of_node_put(node);
                node = NULL;
                args = NULL;
                cur_index++;
        }

        if (!node) {
                /*
                 * args w/o node indicates that the loop above has stopped at
                 * the 'hole' cell. Report this differently.
                 */
                if (args)
                        ret = -EEXIST;
                else
                        ret = -ENOENT;
                goto err0;
        }

        if (out_node)
                *out_node = node;
        if (out_args)
                *out_args = args;

        return 0;
err1:
        of_node_put(node);
err0:
        pr_debug("%s failed with status %d\n", __func__, ret);
        return ret;
}
EXPORT_SYMBOL(of_parse_phandles_with_args);