drivers/of/base.c

   1 /*
   2  * Procedures for creating, accessing and interpreting the device tree.
   3  *
   4  * Paul Mackerras       August 1996.
   5  * Copyright (C) 1996-2005 Paul Mackerras.
   6  *
   7  *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
   8  *    {engebret|bergner}@us.ibm.com
   9  *
  10  *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
  11  *
  12  *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell.
  13  *
  14  *      This program is free software; you can redistribute it and/or
  15  *      modify it under the terms of the GNU General Public License
  16  *      as published by the Free Software Foundation; either version
  17  *      2 of the License, or (at your option) any later version.
  18  */
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/spinlock.h>
  22
  23 struct device_node *allnodes;
  24
  25 /* use when traversing tree through the allnext, child, sibling,
  26  * or parent members of struct device_node.
  27  */
  28 DEFINE_RWLOCK(devtree_lock);
  29
  30 int of_n_addr_cells(struct device_node *np)
  31 {
  32         const int *ip;
  33
  34         do {
  35                 if (np->parent)
  36                         np = np->parent;
  37                 ip = of_get_property(np, "#address-cells", NULL);
  38                 if (ip)
  39                         return *ip;
  40         } while (np->parent);
  41         /* No #address-cells property for the root node */
  42         return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  43 }
  44 EXPORT_SYMBOL(of_n_addr_cells);
  45
  46 int of_n_size_cells(struct device_node *np)
  47 {
  48         const int *ip;
  49
  50         do {
  51                 if (np->parent)
  52                         np = np->parent;
  53                 ip = of_get_property(np, "#size-cells", NULL);
  54                 if (ip)
  55                         return *ip;
  56         } while (np->parent);
  57         /* No #size-cells property for the root node */
  58         return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  59 }
  60 EXPORT_SYMBOL(of_n_size_cells);
  61
  62 struct property *of_find_property(const struct device_node *np,
  63                                   const char *name,
  64                                   int *lenp)
  65 {
  66         struct property *pp;
  67
  68         read_lock(&devtree_lock);
  69         for (pp = np->properties; pp != 0; pp = pp->next) {
  70                 if (of_prop_cmp(pp->name, name) == 0) {
  71                         if (lenp != 0)
  72                                 *lenp = pp->length;
  73                         break;
  74                 }
  75         }
  76         read_unlock(&devtree_lock);
  77
  78         return pp;
  79 }
  80 EXPORT_SYMBOL(of_find_property);
  81
  82 /*
  83  * Find a property with a given name for a given node
  84  * and return the value.
  85  */
  86 const void *of_get_property(const struct device_node *np, const char *name,
  87                          int *lenp)
  88 {
  89         struct property *pp = of_find_property(np, name, lenp);
  90
  91         return pp ? pp->value : NULL;
  92 }
  93 EXPORT_SYMBOL(of_get_property);
  94
  95 /** Checks if the given "compat" string matches one of the strings in
  96  * the device's "compatible" property
  97  */
  98 int of_device_is_compatible(const struct device_node *device,
  99                 const char *compat)
 100 {
 101         const char* cp;
 102         int cplen, l;
 103
 104         cp = of_get_property(device, "compatible", &cplen);
 105         if (cp == NULL)
 106                 return 0;
 107         while (cplen > 0) {
 108                 if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
 109                         return 1;
 110                 l = strlen(cp) + 1;
 111                 cp += l;
 112                 cplen -= l;
 113         }
 114
 115         return 0;
 116 }
 117 EXPORT_SYMBOL(of_device_is_compatible);
 118
 119 /**
 120  *      of_get_parent - Get a node's parent if any
 121  *      @node:  Node to get parent
 122  *
 123  *      Returns a node pointer with refcount incremented, use
 124  *      of_node_put() on it when done.
 125  */
 126 struct device_node *of_get_parent(const struct device_node *node)
 127 {
 128         struct device_node *np;
 129
 130         if (!node)
 131                 return NULL;
 132
 133         read_lock(&devtree_lock);
 134         np = of_node_get(node->parent);
 135         read_unlock(&devtree_lock);
 136         return np;
 137 }
 138 EXPORT_SYMBOL(of_get_parent);
 139
 140 /**
 141  *      of_get_next_child - Iterate a node childs
 142  *      @node:  parent node
 143  *      @prev:  previous child of the parent node, or NULL to get first
 144  *
 145  *      Returns a node pointer with refcount incremented, use
 146  *      of_node_put() on it when done.
 147  */
 148 struct device_node *of_get_next_child(const struct device_node *node,
 149         struct device_node *prev)
 150 {
 151         struct device_node *next;
 152
 153         read_lock(&devtree_lock);
 154         next = prev ? prev->sibling : node->child;
 155         for (; next; next = next->sibling)
 156                 if (of_node_get(next))
 157                         break;
 158         of_node_put(prev);
 159         read_unlock(&devtree_lock);
 160         return next;
 161 }
 162 EXPORT_SYMBOL(of_get_next_child);
 163
 164 /**
 165  *      of_find_node_by_path - Find a node matching a full OF path
 166  *      @path:  The full path to match
 167  *
 168  *      Returns a node pointer with refcount incremented, use
 169  *      of_node_put() on it when done.
 170  */
 171 struct device_node *of_find_node_by_path(const char *path)
 172 {
 173         struct device_node *np = allnodes;
 174
 175         read_lock(&devtree_lock);
 176         for (; np; np = np->allnext) {
 177                 if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
 178                     && of_node_get(np))
 179                         break;
 180         }
 181         read_unlock(&devtree_lock);
 182         return np;
 183 }
 184 EXPORT_SYMBOL(of_find_node_by_path);
 185
 186 /**
 187  *      of_find_node_by_name - Find a node by its "name" property
 188  *      @from:  The node to start searching from or NULL, the node
 189  *              you pass will not be searched, only the next one
 190  *              will; typically, you pass what the previous call
 191  *              returned. of_node_put() will be called on it
 192  *      @name:  The name string to match against
 193  *
 194  *      Returns a node pointer with refcount incremented, use
 195  *      of_node_put() on it when done.
 196  */
 197 struct device_node *of_find_node_by_name(struct device_node *from,
 198         const char *name)
 199 {
 200         struct device_node *np;
 201
 202         read_lock(&devtree_lock);
 203         np = from ? from->allnext : allnodes;
 204         for (; np; np = np->allnext)
 205                 if (np->name && (of_node_cmp(np->name, name) == 0)
 206                     && of_node_get(np))
 207                         break;
 208         of_node_put(from);
 209         read_unlock(&devtree_lock);
 210         return np;
 211 }
 212 EXPORT_SYMBOL(of_find_node_by_name);
 213
 214 /**
 215  *      of_find_node_by_type - Find a node by its "device_type" property
 216  *      @from:  The node to start searching from, or NULL to start searching
 217  *              the entire device tree. The node you pass will not be
 218  *              searched, only the next one will; typically, you pass
 219  *              what the previous call returned. of_node_put() will be
 220  *              called on from for you.
 221  *      @type:  The type string to match against
 222  *
 223  *      Returns a node pointer with refcount incremented, use
 224  *      of_node_put() on it when done.
 225  */
 226 struct device_node *of_find_node_by_type(struct device_node *from,
 227         const char *type)
 228 {
 229         struct device_node *np;
 230
 231         read_lock(&devtree_lock);
 232         np = from ? from->allnext : allnodes;
 233         for (; np; np = np->allnext)
 234                 if (np->type && (of_node_cmp(np->type, type) == 0)
 235                     && of_node_get(np))
 236                         break;
 237         of_node_put(from);
 238         read_unlock(&devtree_lock);
 239         return np;
 240 }
 241 EXPORT_SYMBOL(of_find_node_by_type);
 242
 243 /**
 244  *      of_find_compatible_node - Find a node based on type and one of the
 245  *                                tokens in its "compatible" property
 246  *      @from:          The node to start searching from or NULL, the node
 247  *                      you pass will not be searched, only the next one
 248  *                      will; typically, you pass what the previous call
 249  *                      returned. of_node_put() will be called on it
 250  *      @type:          The type string to match "device_type" or NULL to ignore
 251  *      @compatible:    The string to match to one of the tokens in the device
 252  *                      "compatible" list.
 253  *
 254  *      Returns a node pointer with refcount incremented, use
 255  *      of_node_put() on it when done.
 256  */
 257 struct device_node *of_find_compatible_node(struct device_node *from,
 258         const char *type, const char *compatible)
 259 {
 260         struct device_node *np;
 261
 262         read_lock(&devtree_lock);
 263         np = from ? from->allnext : allnodes;
 264         for (; np; np = np->allnext) {
 265                 if (type
 266                     && !(np->type && (of_node_cmp(np->type, type) == 0)))
 267                         continue;
 268                 if (of_device_is_compatible(np, compatible) && of_node_get(np))
 269                         break;
 270         }
 271         of_node_put(from);
 272         read_unlock(&devtree_lock);
 273         return np;
 274 }
 275 EXPORT_SYMBOL(of_find_compatible_node);