drivers/of/resolver.c

   1 /*
   2  * Functions for dealing with DT resolution
   3  *
   4  * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
   5  * Copyright (C) 2012 Texas Instruments Inc.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * version 2 as published by the Free Software Foundation.
  10  */
  11
  12 #define pr_fmt(fmt)     "OF: resolver: " fmt
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/of_device.h>
  18 #include <linux/string.h>
  19 #include <linux/ctype.h>
  20 #include <linux/errno.h>
  21 #include <linux/slab.h>
  22
  23 #include "of_private.h"
  24
  25 /* illegal phandle value (set when unresolved) */
  26 #define OF_PHANDLE_ILLEGAL      0xdeadbeef
  27
  28 static phandle live_tree_max_phandle(void)
  29 {
  30         struct device_node *node;
  31         phandle phandle;
  32         unsigned long flags;
  33
  34         raw_spin_lock_irqsave(&devtree_lock, flags);
  35         phandle = 0;
  36         for_each_of_allnodes(node) {
  37                 if (node->phandle != OF_PHANDLE_ILLEGAL &&
  38                                 node->phandle > phandle)
  39                         phandle = node->phandle;
  40         }
  41         raw_spin_unlock_irqrestore(&devtree_lock, flags);
  42
  43         return phandle;
  44 }
  45
  46 static void adjust_overlay_phandles(struct device_node *overlay,
  47                 int phandle_delta)
  48 {
  49         struct device_node *child;
  50         struct property *prop;
  51         phandle phandle;
  52
  53         /* adjust node's phandle in node */
  54         if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
  55                 overlay->phandle += phandle_delta;
  56
  57         /* copy adjusted phandle into *phandle properties */
  58         for_each_property_of_node(overlay, prop) {
  59
  60                 if (of_prop_cmp(prop->name, "phandle") &&
  61                     of_prop_cmp(prop->name, "linux,phandle"))
  62                         continue;
  63
  64                 if (prop->length < 4)
  65                         continue;
  66
  67                 phandle = be32_to_cpup(prop->value);
  68                 if (phandle == OF_PHANDLE_ILLEGAL)
  69                         continue;
  70
  71                 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
  72         }
  73
  74         for_each_child_of_node(overlay, child)
  75                 adjust_overlay_phandles(child, phandle_delta);
  76 }
  77
  78 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
  79                 struct property *prop_fixup, phandle phandle)
  80 {
  81         struct device_node *refnode;
  82         struct property *prop;
  83         char *value, *cur, *end, *node_path, *prop_name, *s;
  84         int offset, len;
  85         int err = 0;
  86
  87         value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
  88         if (!value)
  89                 return -ENOMEM;
  90
  91         /* prop_fixup contains a list of tuples of path:property_name:offset */
  92         end = value + prop_fixup->length;
  93         for (cur = value; cur < end; cur += len + 1) {
  94                 len = strlen(cur);
  95
  96                 node_path = cur;
  97                 s = strchr(cur, ':');
  98                 if (!s) {
  99                         err = -EINVAL;
 100                         goto err_fail;
 101                 }
 102                 *s++ = '\0';
 103
 104                 prop_name = s;
 105                 s = strchr(s, ':');
 106                 if (!s) {
 107                         err = -EINVAL;
 108                         goto err_fail;
 109                 }
 110                 *s++ = '\0';
 111
 112                 err = kstrtoint(s, 10, &offset);
 113                 if (err)
 114                         goto err_fail;
 115
 116                 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
 117                 if (!refnode)
 118                         continue;
 119
 120                 for_each_property_of_node(refnode, prop) {
 121                         if (!of_prop_cmp(prop->name, prop_name))
 122                                 break;
 123                 }
 124                 of_node_put(refnode);
 125
 126                 if (!prop) {
 127                         err = -ENOENT;
 128                         goto err_fail;
 129                 }
 130
 131                 if (offset < 0 || offset + sizeof(__be32) > prop->length) {
 132                         err = -EINVAL;
 133                         goto err_fail;
 134                 }
 135
 136                 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
 137         }
 138
 139 err_fail:
 140         kfree(value);
 141         return err;
 142 }
 143
 144 /* compare nodes taking into account that 'name' strips out the @ part */
 145 static int node_name_cmp(const struct device_node *dn1,
 146                 const struct device_node *dn2)
 147 {
 148         const char *n1 = kbasename(dn1->full_name);
 149         const char *n2 = kbasename(dn2->full_name);
 150
 151         return of_node_cmp(n1, n2);
 152 }
 153
 154 /*
 155  * Adjust the local phandle references by the given phandle delta.
 156  *
 157  * Subtree @local_fixups, which is overlay node __local_fixups__,
 158  * mirrors the fragment node structure at the root of the overlay.
 159  *
 160  * For each property in the fragments that contains a phandle reference,
 161  * @local_fixups has a property of the same name that contains a list
 162  * of offsets of the phandle reference(s) within the respective property
 163  * value(s).  The values at these offsets will be fixed up.
 164  */
 165 static int adjust_local_phandle_references(struct device_node *local_fixups,
 166                 struct device_node *overlay, int phandle_delta)
 167 {
 168         struct device_node *child, *overlay_child;
 169         struct property *prop_fix, *prop;
 170         int err, i, count;
 171         unsigned int off;
 172
 173         if (!local_fixups)
 174                 return 0;
 175
 176         for_each_property_of_node(local_fixups, prop_fix) {
 177
 178                 /* skip properties added automatically */
 179                 if (!of_prop_cmp(prop_fix->name, "name") ||
 180                     !of_prop_cmp(prop_fix->name, "phandle") ||
 181                     !of_prop_cmp(prop_fix->name, "linux,phandle"))
 182                         continue;
 183
 184                 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
 185                         return -EINVAL;
 186                 count = prop_fix->length / sizeof(__be32);
 187
 188                 for_each_property_of_node(overlay, prop) {
 189                         if (!of_prop_cmp(prop->name, prop_fix->name))
 190                                 break;
 191                 }
 192
 193                 if (!prop)
 194                         return -EINVAL;
 195
 196                 for (i = 0; i < count; i++) {
 197                         off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
 198                         if ((off + 4) > prop->length)
 199                                 return -EINVAL;
 200
 201                         be32_add_cpu(prop->value + off, phandle_delta);
 202                 }
 203         }
 204
 205         /*
 206          * These nested loops recurse down two subtrees in parallel, where the
 207          * node names in the two subtrees match.
 208          *
 209          * The roots of the subtrees are the overlay's __local_fixups__ node
 210          * and the overlay's root node.
 211          */
 212         for_each_child_of_node(local_fixups, child) {
 213
 214                 for_each_child_of_node(overlay, overlay_child)
 215                         if (!node_name_cmp(child, overlay_child))
 216                                 break;
 217
 218                 if (!overlay_child)
 219                         return -EINVAL;
 220
 221                 err = adjust_local_phandle_references(child, overlay_child,
 222                                 phandle_delta);
 223                 if (err)
 224                         return err;
 225         }
 226
 227         return 0;
 228 }
 229
 230 /**
 231  * of_resolve_phandles - Relocate and resolve overlay against live tree
 232  *
 233  * @overlay:    Pointer to devicetree overlay to relocate and resolve
 234  *
 235  * Modify (relocate) values of local phandles in @overlay to a range that
 236  * does not conflict with the live expanded devicetree.  Update references
 237  * to the local phandles in @overlay.  Update (resolve) phandle references
 238  * in @overlay that refer to the live expanded devicetree.
 239  *
 240  * Phandle values in the live tree are in the range of
 241  * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
 242  * also begin with at 1.  Adjust the phandle values in the overlay to begin
 243  * at live_tree_max_phandle() + 1.  Update references to the phandles to
 244  * the adjusted phandle values.
 245  *
 246  * The name of each property in the "__fixups__" node in the overlay matches
 247  * the name of a symbol (a label) in the live tree.  The values of each
 248  * property in the "__fixups__" node is a list of the property values in the
 249  * overlay that need to be updated to contain the phandle reference
 250  * corresponding to that symbol in the live tree.  Update the references in
 251  * the overlay with the phandle values in the live tree.
 252  *
 253  * @overlay must be detached.
 254  *
 255  * Resolving and applying @overlay to the live expanded devicetree must be
 256  * protected by a mechanism to ensure that multiple overlays are processed
 257  * in a single threaded manner so that multiple overlays will not relocate
 258  * phandles to overlapping ranges.  The mechanism to enforce this is not
 259  * yet implemented.
 260  *
 261  * Return: %0 on success or a negative error value on error.
 262  */
 263 int of_resolve_phandles(struct device_node *overlay)
 264 {
 265         struct device_node *child, *local_fixups, *refnode;
 266         struct device_node *tree_symbols, *overlay_fixups;
 267         struct property *prop;
 268         const char *refpath;
 269         phandle phandle, phandle_delta;
 270         int err;
 271
 272         tree_symbols = NULL;
 273
 274         if (!overlay) {
 275                 pr_err("null overlay\n");
 276                 err = -EINVAL;
 277                 goto out;
 278         }
 279
 280 #if 0
 281         Temporarily disable check so that old style overlay unittests
 282         do not fail when of_resolve_phandles() is moved into
 283         of_overlay_apply().
 284
 285         if (!of_node_check_flag(overlay, OF_DETACHED)) {
 286                 pr_err("overlay not detached\n");
 287                 err = -EINVAL;
 288                 goto out;
 289         }
 290 #endif
 291
 292         phandle_delta = live_tree_max_phandle() + 1;
 293         adjust_overlay_phandles(overlay, phandle_delta);
 294
 295         for_each_child_of_node(overlay, local_fixups)
 296                 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
 297                         break;
 298
 299         err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
 300         if (err)
 301                 goto out;
 302
 303         overlay_fixups = NULL;
 304
 305         for_each_child_of_node(overlay, child) {
 306                 if (!of_node_cmp(child->name, "__fixups__"))
 307                         overlay_fixups = child;
 308         }
 309
 310         if (!overlay_fixups) {
 311                 err = 0;
 312                 goto out;
 313         }
 314
 315         tree_symbols = of_find_node_by_path("/__symbols__");
 316         if (!tree_symbols) {
 317                 pr_err("no symbols in root of device tree.\n");
 318                 err = -EINVAL;
 319                 goto out;
 320         }
 321
 322         for_each_property_of_node(overlay_fixups, prop) {
 323
 324                 /* skip properties added automatically */
 325                 if (!of_prop_cmp(prop->name, "name"))
 326                         continue;
 327
 328                 err = of_property_read_string(tree_symbols,
 329                                 prop->name, &refpath);
 330                 if (err)
 331                         goto out;
 332
 333                 refnode = of_find_node_by_path(refpath);
 334                 if (!refnode) {
 335                         err = -ENOENT;
 336                         goto out;
 337                 }
 338
 339                 phandle = refnode->phandle;
 340                 of_node_put(refnode);
 341
 342                 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
 343                 if (err)
 344                         break;
 345         }
 346
 347 out:
 348         if (err)
 349                 pr_err("overlay phandle fixup failed: %d\n", err);
 350         of_node_put(tree_symbols);
 351
 352         return err;
 353 }
 354 EXPORT_SYMBOL_GPL(of_resolve_phandles);