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         if (!np)
  69                 return NULL;
  70
  71         read_lock(&devtree_lock);
  72         for (pp = np->properties; pp != 0; pp = pp->next) {
  73                 if (of_prop_cmp(pp->name, name) == 0) {
  74                         if (lenp != 0)
  75                                 *lenp = pp->length;
  76                         break;
  77                 }
  78         }
  79         read_unlock(&devtree_lock);
  80
  81         return pp;
  82 }
  83 EXPORT_SYMBOL(of_find_property);
  84
  85 /*
  86  * Find a property with a given name for a given node
  87  * and return the value.
  88  */
  89 const void *of_get_property(const struct device_node *np, const char *name,
  90                          int *lenp)
  91 {
  92         struct property *pp = of_find_property(np, name, lenp);
  93
  94         return pp ? pp->value : NULL;
  95 }
  96 EXPORT_SYMBOL(of_get_property);
  97
  98 /** Checks if the given "compat" string matches one of the strings in
  99  * the device's "compatible" property
 100  */
 101 int of_device_is_compatible(const struct device_node *device,
 102                 const char *compat)
 103 {
 104         const char* cp;
 105         int cplen, l;
 106
 107         cp = of_get_property(device, "compatible", &cplen);
 108         if (cp == NULL)
 109                 return 0;
 110         while (cplen > 0) {
 111                 if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
 112                         return 1;
 113                 l = strlen(cp) + 1;
 114                 cp += l;
 115                 cplen -= l;
 116         }
 117
 118         return 0;
 119 }
 120 EXPORT_SYMBOL(of_device_is_compatible);
 121
 122 /**
 123  *  of_device_is_available - check if a device is available for use
 124  *
 125  *  @device: Node to check for availability
 126  *
 127  *  Returns 1 if the status property is absent or set to "okay" or "ok",
 128  *  0 otherwise
 129  */
 130 int of_device_is_available(const struct device_node *device)
 131 {
 132         const char *status;
 133         int statlen;
 134
 135         status = of_get_property(device, "status", &statlen);
 136         if (status == NULL)
 137                 return 1;
 138
 139         if (statlen > 0) {
 140                 if (!strcmp(status, "okay") || !strcmp(status, "ok"))
 141                         return 1;
 142         }
 143
 144         return 0;
 145 }
 146 EXPORT_SYMBOL(of_device_is_available);
 147
 148 /**
 149  *      of_get_parent - Get a node's parent if any
 150  *      @node:  Node to get parent
 151  *
 152  *      Returns a node pointer with refcount incremented, use
 153  *      of_node_put() on it when done.
 154  */
 155 struct device_node *of_get_parent(const struct device_node *node)
 156 {
 157         struct device_node *np;
 158
 159         if (!node)
 160                 return NULL;
 161
 162         read_lock(&devtree_lock);
 163         np = of_node_get(node->parent);
 164         read_unlock(&devtree_lock);
 165         return np;
 166 }
 167 EXPORT_SYMBOL(of_get_parent);
 168
 169 /**
 170  *      of_get_next_parent - Iterate to a node's parent
 171  *      @node:  Node to get parent of
 172  *
 173  *      This is like of_get_parent() except that it drops the
 174  *      refcount on the passed node, making it suitable for iterating
 175  *      through a node's parents.
 176  *
 177  *      Returns a node pointer with refcount incremented, use
 178  *      of_node_put() on it when done.
 179  */
 180 struct device_node *of_get_next_parent(struct device_node *node)
 181 {
 182         struct device_node *parent;
 183
 184         if (!node)
 185                 return NULL;
 186
 187         read_lock(&devtree_lock);
 188         parent = of_node_get(node->parent);
 189         of_node_put(node);
 190         read_unlock(&devtree_lock);
 191         return parent;
 192 }
 193
 194 /**
 195  *      of_get_next_child - Iterate a node childs
 196  *      @node:  parent node
 197  *      @prev:  previous child of the parent node, or NULL to get first
 198  *
 199  *      Returns a node pointer with refcount incremented, use
 200  *      of_node_put() on it when done.
 201  */
 202 struct device_node *of_get_next_child(const struct device_node *node,
 203         struct device_node *prev)
 204 {
 205         struct device_node *next;
 206
 207         read_lock(&devtree_lock);
 208         next = prev ? prev->sibling : node->child;
 209         for (; next; next = next->sibling)
 210                 if (of_node_get(next))
 211                         break;
 212         of_node_put(prev);
 213         read_unlock(&devtree_lock);
 214         return next;
 215 }
 216 EXPORT_SYMBOL(of_get_next_child);
 217
 218 /**
 219  *      of_find_node_by_path - Find a node matching a full OF path
 220  *      @path:  The full path to match
 221  *
 222  *      Returns a node pointer with refcount incremented, use
 223  *      of_node_put() on it when done.
 224  */
 225 struct device_node *of_find_node_by_path(const char *path)
 226 {
 227         struct device_node *np = allnodes;
 228
 229         read_lock(&devtree_lock);
 230         for (; np; np = np->allnext) {
 231                 if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
 232                     && of_node_get(np))
 233                         break;
 234         }
 235         read_unlock(&devtree_lock);
 236         return np;
 237 }
 238 EXPORT_SYMBOL(of_find_node_by_path);
 239
 240 /**
 241  *      of_find_node_by_name - Find a node by its "name" property
 242  *      @from:  The node to start searching from or NULL, the node
 243  *              you pass will not be searched, only the next one
 244  *              will; typically, you pass what the previous call
 245  *              returned. of_node_put() will be called on it
 246  *      @name:  The name 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_name(struct device_node *from,
 252         const char *name)
 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->name && (of_node_cmp(np->name, name) == 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_name);
 267
 268 /**
 269  *      of_find_node_by_type - Find a node by its "device_type" property
 270  *      @from:  The node to start searching from, or NULL to start searching
 271  *              the entire device tree. The node you pass will not be
 272  *              searched, only the next one will; typically, you pass
 273  *              what the previous call returned. of_node_put() will be
 274  *              called on from for you.
 275  *      @type:  The type string to match against
 276  *
 277  *      Returns a node pointer with refcount incremented, use
 278  *      of_node_put() on it when done.
 279  */
 280 struct device_node *of_find_node_by_type(struct device_node *from,
 281         const char *type)
 282 {
 283         struct device_node *np;
 284
 285         read_lock(&devtree_lock);
 286         np = from ? from->allnext : allnodes;
 287         for (; np; np = np->allnext)
 288                 if (np->type && (of_node_cmp(np->type, type) == 0)
 289                     && of_node_get(np))
 290                         break;
 291         of_node_put(from);
 292         read_unlock(&devtree_lock);
 293         return np;
 294 }
 295 EXPORT_SYMBOL(of_find_node_by_type);
 296
 297 /**
 298  *      of_find_compatible_node - Find a node based on type and one of the
 299  *                                tokens in its "compatible" property
 300  *      @from:          The node to start searching from or NULL, the node
 301  *                      you pass will not be searched, only the next one
 302  *                      will; typically, you pass what the previous call
 303  *                      returned. of_node_put() will be called on it
 304  *      @type:          The type string to match "device_type" or NULL to ignore
 305  *      @compatible:    The string to match to one of the tokens in the device
 306  *                      "compatible" list.
 307  *
 308  *      Returns a node pointer with refcount incremented, use
 309  *      of_node_put() on it when done.
 310  */
 311 struct device_node *of_find_compatible_node(struct device_node *from,
 312         const char *type, const char *compatible)
 313 {
 314         struct device_node *np;
 315
 316         read_lock(&devtree_lock);
 317         np = from ? from->allnext : allnodes;
 318         for (; np; np = np->allnext) {
 319                 if (type
 320                     && !(np->type && (of_node_cmp(np->type, type) == 0)))
 321                         continue;
 322                 if (of_device_is_compatible(np, compatible) && of_node_get(np))
 323                         break;
 324         }
 325         of_node_put(from);
 326         read_unlock(&devtree_lock);
 327         return np;
 328 }
 329 EXPORT_SYMBOL(of_find_compatible_node);
 330
 331 /**
 332  * of_match_node - Tell if an device_node has a matching of_match structure
 333  *      @matches:       array of of device match structures to search in
 334  *      @node:          the of device structure to match against
 335  *
 336  *      Low level utility function used by device matching.
 337  */
 338 const struct of_device_id *of_match_node(const struct of_device_id *matches,
 339                                          const struct device_node *node)
 340 {
 341         while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
 342                 int match = 1;
 343                 if (matches->name[0])
 344                         match &= node->name
 345                                 && !strcmp(matches->name, node->name);
 346                 if (matches->type[0])
 347                         match &= node->type
 348                                 && !strcmp(matches->type, node->type);
 349                 if (matches->compatible[0])
 350                         match &= of_device_is_compatible(node,
 351                                                 matches->compatible);
 352                 if (match)
 353                         return matches;
 354                 matches++;
 355         }
 356         return NULL;
 357 }
 358 EXPORT_SYMBOL(of_match_node);
 359
 360 /**
 361  *      of_find_matching_node - Find a node based on an of_device_id match
 362  *                              table.
 363  *      @from:          The node to start searching from or NULL, the node
 364  *                      you pass will not be searched, only the next one
 365  *                      will; typically, you pass what the previous call
 366  *                      returned. of_node_put() will be called on it
 367  *      @matches:       array of of device match structures to search in
 368  *
 369  *      Returns a node pointer with refcount incremented, use
 370  *      of_node_put() on it when done.
 371  */
 372 struct device_node *of_find_matching_node(struct device_node *from,
 373                                           const struct of_device_id *matches)
 374 {
 375         struct device_node *np;
 376
 377         read_lock(&devtree_lock);
 378         np = from ? from->allnext : allnodes;
 379         for (; np; np = np->allnext) {
 380                 if (of_match_node(matches, np) && of_node_get(np))
 381                         break;
 382         }
 383         of_node_put(from);
 384         read_unlock(&devtree_lock);
 385         return np;
 386 }
 387 EXPORT_SYMBOL(of_find_matching_node);