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_parent - Iterate to a node's parent
 142  *      @node:  Node to get parent of
 143  *
 144  *      This is like of_get_parent() except that it drops the
 145  *      refcount on the passed node, making it suitable for iterating
 146  *      through a node's parents.
 147  *
 148  *      Returns a node pointer with refcount incremented, use
 149  *      of_node_put() on it when done.
 150  */
 151 struct device_node *of_get_next_parent(struct device_node *node)
 152 {
 153         struct device_node *parent;
 154
 155         if (!node)
 156                 return NULL;
 157
 158         read_lock(&devtree_lock);
 159         parent = of_node_get(node->parent);
 160         of_node_put(node);
 161         read_unlock(&devtree_lock);
 162         return parent;
 163 }
 164
 165 /**
 166  *      of_get_next_child - Iterate a node childs
 167  *      @node:  parent node
 168  *      @prev:  previous child of the parent node, or NULL to get first
 169  *
 170  *      Returns a node pointer with refcount incremented, use
 171  *      of_node_put() on it when done.
 172  */
 173 struct device_node *of_get_next_child(const struct device_node *node,
 174         struct device_node *prev)
 175 {
 176         struct device_node *next;
 177
 178         read_lock(&devtree_lock);
 179         next = prev ? prev->sibling : node->child;
 180         for (; next; next = next->sibling)
 181                 if (of_node_get(next))
 182                         break;
 183         of_node_put(prev);
 184         read_unlock(&devtree_lock);
 185         return next;
 186 }
 187 EXPORT_SYMBOL(of_get_next_child);
 188
 189 /**
 190  *      of_find_node_by_path - Find a node matching a full OF path
 191  *      @path:  The full path to match
 192  *
 193  *      Returns a node pointer with refcount incremented, use
 194  *      of_node_put() on it when done.
 195  */
 196 struct device_node *of_find_node_by_path(const char *path)
 197 {
 198         struct device_node *np = allnodes;
 199
 200         read_lock(&devtree_lock);
 201         for (; np; np = np->allnext) {
 202                 if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
 203                     && of_node_get(np))
 204                         break;
 205         }
 206         read_unlock(&devtree_lock);
 207         return np;
 208 }
 209 EXPORT_SYMBOL(of_find_node_by_path);
 210
 211 /**
 212  *      of_find_node_by_name - Find a node by its "name" property
 213  *      @from:  The node to start searching from or NULL, the node
 214  *              you pass will not be searched, only the next one
 215  *              will; typically, you pass what the previous call
 216  *              returned. of_node_put() will be called on it
 217  *      @name:  The name string to match against
 218  *
 219  *      Returns a node pointer with refcount incremented, use
 220  *      of_node_put() on it when done.
 221  */
 222 struct device_node *of_find_node_by_name(struct device_node *from,
 223         const char *name)
 224 {
 225         struct device_node *np;
 226
 227         read_lock(&devtree_lock);
 228         np = from ? from->allnext : allnodes;
 229         for (; np; np = np->allnext)
 230                 if (np->name && (of_node_cmp(np->name, name) == 0)
 231                     && of_node_get(np))
 232                         break;
 233         of_node_put(from);
 234         read_unlock(&devtree_lock);
 235         return np;
 236 }
 237 EXPORT_SYMBOL(of_find_node_by_name);
 238
 239 /**
 240  *      of_find_node_by_type - Find a node by its "device_type" property
 241  *      @from:  The node to start searching from, or NULL to start searching
 242  *              the entire device tree. The node you pass will not be
 243  *              searched, only the next one will; typically, you pass
 244  *              what the previous call returned. of_node_put() will be
 245  *              called on from for you.
 246  *      @type:  The type string to match against
 247  *
 248  *      Returns a node pointer with refcount incremented, use
 249  *      of_node_put() on it when done.
 250  */
 251 struct device_node *of_find_node_by_type(struct device_node *from,
 252         const char *type)
 253 {
 254         struct device_node *np;
 255
 256         read_lock(&devtree_lock);
 257         np = from ? from->allnext : allnodes;
 258         for (; np; np = np->allnext)
 259                 if (np->type && (of_node_cmp(np->type, type) == 0)
 260                     && of_node_get(np))
 261                         break;
 262         of_node_put(from);
 263         read_unlock(&devtree_lock);
 264         return np;
 265 }
 266 EXPORT_SYMBOL(of_find_node_by_type);
 267
 268 /**
 269  *      of_find_compatible_node - Find a node based on type and one of the
 270  *                                tokens in its "compatible" property
 271  *      @from:          The node to start searching from or NULL, the node
 272  *                      you pass will not be searched, only the next one
 273  *                      will; typically, you pass what the previous call
 274  *                      returned. of_node_put() will be called on it
 275  *      @type:          The type string to match "device_type" or NULL to ignore
 276  *      @compatible:    The string to match to one of the tokens in the device
 277  *                      "compatible" list.
 278  *
 279  *      Returns a node pointer with refcount incremented, use
 280  *      of_node_put() on it when done.
 281  */
 282 struct device_node *of_find_compatible_node(struct device_node *from,
 283         const char *type, const char *compatible)
 284 {
 285         struct device_node *np;
 286
 287         read_lock(&devtree_lock);
 288         np = from ? from->allnext : allnodes;
 289         for (; np; np = np->allnext) {
 290                 if (type
 291                     && !(np->type && (of_node_cmp(np->type, type) == 0)))
 292                         continue;
 293                 if (of_device_is_compatible(np, compatible) && of_node_get(np))
 294                         break;
 295         }
 296         of_node_put(from);
 297         read_unlock(&devtree_lock);
 298         return np;
 299 }
 300 EXPORT_SYMBOL(of_find_compatible_node);
 301
 302 /**
 303  * of_match_node - Tell if an device_node has a matching of_match structure
 304  *      @matches:       array of of device match structures to search in
 305  *      @node:          the of device structure to match against
 306  *
 307  *      Low level utility function used by device matching.
 308  */
 309 const struct of_device_id *of_match_node(const struct of_device_id *matches,
 310                                          const struct device_node *node)
 311 {
 312         while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
 313                 int match = 1;
 314                 if (matches->name[0])
 315                         match &= node->name
 316                                 && !strcmp(matches->name, node->name);
 317                 if (matches->type[0])
 318                         match &= node->type
 319                                 && !strcmp(matches->type, node->type);
 320                 if (matches->compatible[0])
 321                         match &= of_device_is_compatible(node,
 322                                                 matches->compatible);
 323                 if (match)
 324                         return matches;
 325                 matches++;
 326         }
 327         return NULL;
 328 }
 329 EXPORT_SYMBOL(of_match_node);
 330
 331 /**
 332  *      of_find_matching_node - Find a node based on an of_device_id match
 333  *                              table.
 334  *      @from:          The node to start searching from or NULL, the node
 335  *                      you pass will not be searched, only the next one
 336  *                      will; typically, you pass what the previous call
 337  *                      returned. of_node_put() will be called on it
 338  *      @matches:       array of of device match structures to search in
 339  *
 340  *      Returns a node pointer with refcount incremented, use
 341  *      of_node_put() on it when done.
 342  */
 343 struct device_node *of_find_matching_node(struct device_node *from,
 344                                           const struct of_device_id *matches)
 345 {
 346         struct device_node *np;
 347
 348         read_lock(&devtree_lock);
 349         np = from ? from->allnext : allnodes;
 350         for (; np; np = np->allnext) {
 351                 if (of_match_node(matches, np) && of_node_get(np))
 352                         break;
 353         }
 354         of_node_put(from);
 355         read_unlock(&devtree_lock);
 356         return np;
 357 }
 358 EXPORT_SYMBOL(of_find_matching_node);