drivers/of/resolver.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Functions for dealing with DT resolution
   4  *
   5  * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
   6  * Copyright (C) 2012 Texas Instruments Inc.
   7  */
   8
   9 #define pr_fmt(fmt)     "OF: resolver: " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_device.h>
  15 #include <linux/string.h>
  16 #include <linux/ctype.h>
  17 #include <linux/errno.h>
  18 #include <linux/slab.h>
  19
  20 #include "of_private.h"
  21
  22 /* illegal phandle value (set when unresolved) */
  23 #define OF_PHANDLE_ILLEGAL      0xdeadbeef
  24
  25 static phandle live_tree_max_phandle(void)
  26 {
  27         struct device_node *node;
  28         phandle phandle;
  29         unsigned long flags;
  30
  31         raw_spin_lock_irqsave(&devtree_lock, flags);
  32         phandle = 0;
  33         for_each_of_allnodes(node) {
  34                 if (node->phandle != OF_PHANDLE_ILLEGAL &&
  35                                 node->phandle > phandle)
  36                         phandle = node->phandle;
  37         }
  38         raw_spin_unlock_irqrestore(&devtree_lock, flags);
  39
  40         return phandle;
  41 }
  42
  43 static void adjust_overlay_phandles(struct device_node *overlay,
  44                 int phandle_delta)
  45 {
  46         struct device_node *child;
  47         struct property *prop;
  48         phandle phandle;
  49
  50         /* adjust node's phandle in node */
  51         if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
  52                 overlay->phandle += phandle_delta;
  53
  54         /* copy adjusted phandle into *phandle properties */
  55         for_each_property_of_node(overlay, prop) {
  56
  57                 if (of_prop_cmp(prop->name, "phandle") &&
  58                     of_prop_cmp(prop->name, "linux,phandle"))
  59                         continue;
  60
  61                 if (prop->length < 4)
  62                         continue;
  63
  64                 phandle = be32_to_cpup(prop->value);
  65                 if (phandle == OF_PHANDLE_ILLEGAL)
  66                         continue;
  67
  68                 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
  69         }
  70
  71         for_each_child_of_node(overlay, child)
  72                 adjust_overlay_phandles(child, phandle_delta);
  73 }
  74
  75 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
  76                 struct property *prop_fixup, phandle phandle)
  77 {
  78         struct device_node *refnode;
  79         struct property *prop;
  80         char *value, *cur, *end, *node_path, *prop_name, *s;
  81         int offset, len;
  82         int err = 0;
  83
  84         value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
  85         if (!value)
  86                 return -ENOMEM;
  87
  88         /* prop_fixup contains a list of tuples of path:property_name:offset */
  89         end = value + prop_fixup->length;
  90         for (cur = value; cur < end; cur += len + 1) {
  91                 len = strlen(cur);
  92
  93                 node_path = cur;
  94                 s = strchr(cur, ':');
  95                 if (!s) {
  96                         err = -EINVAL;
  97                         goto err_fail;
  98                 }
  99                 *s++ = '\0';
 100
 101                 prop_name = s;
 102                 s = strchr(s, ':');
 103                 if (!s) {
 104                         err = -EINVAL;
 105                         goto err_fail;
 106                 }
 107                 *s++ = '\0';
 108
 109                 err = kstrtoint(s, 10, &offset);
 110                 if (err)
 111                         goto err_fail;
 112
 113                 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
 114                 if (!refnode)
 115                         continue;
 116
 117                 for_each_property_of_node(refnode, prop) {
 118                         if (!of_prop_cmp(prop->name, prop_name))
 119                                 break;
 120                 }
 121                 of_node_put(refnode);
 122
 123                 if (!prop) {
 124                         err = -ENOENT;
 125                         goto err_fail;
 126                 }
 127
 128                 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
 129         }
 130
 131 err_fail:
 132         kfree(value);
 133         return err;
 134 }
 135
 136 /* compare nodes taking into account that 'name' strips out the @ part */
 137 static int node_name_cmp(const struct device_node *dn1,
 138                 const struct device_node *dn2)
 139 {
 140         const char *n1 = kbasename(dn1->full_name);
 141         const char *n2 = kbasename(dn2->full_name);
 142
 143         return of_node_cmp(n1, n2);
 144 }
 145
 146 /*
 147  * Adjust the local phandle references by the given phandle delta.
 148  *
 149  * Subtree @local_fixups, which is overlay node __local_fixups__,
 150  * mirrors the fragment node structure at the root of the overlay.
 151  *
 152  * For each property in the fragments that contains a phandle reference,
 153  * @local_fixups has a property of the same name that contains a list
 154  * of offsets of the phandle reference(s) within the respective property
 155  * value(s).  The values at these offsets will be fixed up.
 156  */
 157 static int adjust_local_phandle_references(struct device_node *local_fixups,
 158                 struct device_node *overlay, int phandle_delta)
 159 {
 160         struct device_node *child, *overlay_child;
 161         struct property *prop_fix, *prop;
 162         int err, i, count;
 163         unsigned int off;
 164
 165         if (!local_fixups)
 166                 return 0;
 167
 168         for_each_property_of_node(local_fixups, prop_fix) {
 169
 170                 /* skip properties added automatically */
 171                 if (!of_prop_cmp(prop_fix->name, "name") ||
 172                     !of_prop_cmp(prop_fix->name, "phandle") ||
 173                     !of_prop_cmp(prop_fix->name, "linux,phandle"))
 174                         continue;
 175
 176                 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
 177                         return -EINVAL;
 178                 count = prop_fix->length / sizeof(__be32);
 179
 180                 for_each_property_of_node(overlay, prop) {
 181                         if (!of_prop_cmp(prop->name, prop_fix->name))
 182                                 break;
 183                 }
 184
 185                 if (!prop)
 186                         return -EINVAL;
 187
 188                 for (i = 0; i < count; i++) {
 189                         off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
 190                         if ((off + 4) > prop->length)
 191                                 return -EINVAL;
 192
 193                         be32_add_cpu(prop->value + off, phandle_delta);
 194                 }
 195         }
 196
 197         /*
 198          * These nested loops recurse down two subtrees in parallel, where the
 199          * node names in the two subtrees match.
 200          *
 201          * The roots of the subtrees are the overlay's __local_fixups__ node
 202          * and the overlay's root node.
 203          */
 204         for_each_child_of_node(local_fixups, child) {
 205
 206                 for_each_child_of_node(overlay, overlay_child)
 207                         if (!node_name_cmp(child, overlay_child))
 208                                 break;
 209
 210                 if (!overlay_child)
 211                         return -EINVAL;
 212
 213                 err = adjust_local_phandle_references(child, overlay_child,
 214                                 phandle_delta);
 215                 if (err)
 216                         return err;
 217         }
 218
 219         return 0;
 220 }
 221
 222 /**
 223  * of_resolve_phandles - Relocate and resolve overlay against live tree
 224  *
 225  * @overlay:    Pointer to devicetree overlay to relocate and resolve
 226  *
 227  * Modify (relocate) values of local phandles in @overlay to a range that
 228  * does not conflict with the live expanded devicetree.  Update references
 229  * to the local phandles in @overlay.  Update (resolve) phandle references
 230  * in @overlay that refer to the live expanded devicetree.
 231  *
 232  * Phandle values in the live tree are in the range of
 233  * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
 234  * also begin with at 1.  Adjust the phandle values in the overlay to begin
 235  * at live_tree_max_phandle() + 1.  Update references to the phandles to
 236  * the adjusted phandle values.
 237  *
 238  * The name of each property in the "__fixups__" node in the overlay matches
 239  * the name of a symbol (a label) in the live tree.  The values of each
 240  * property in the "__fixups__" node is a list of the property values in the
 241  * overlay that need to be updated to contain the phandle reference
 242  * corresponding to that symbol in the live tree.  Update the references in
 243  * the overlay with the phandle values in the live tree.
 244  *
 245  * @overlay must be detached.
 246  *
 247  * Resolving and applying @overlay to the live expanded devicetree must be
 248  * protected by a mechanism to ensure that multiple overlays are processed
 249  * in a single threaded manner so that multiple overlays will not relocate
 250  * phandles to overlapping ranges.  The mechanism to enforce this is not
 251  * yet implemented.
 252  *
 253  * Return: %0 on success or a negative error value on error.
 254  */
 255 int of_resolve_phandles(struct device_node *overlay)
 256 {
 257         struct device_node *child, *local_fixups, *refnode;
 258         struct device_node *tree_symbols, *overlay_fixups;
 259         struct property *prop;
 260         const char *refpath;
 261         phandle phandle, phandle_delta;
 262         int err;
 263
 264         tree_symbols = NULL;
 265
 266         if (!overlay) {
 267                 pr_err("null overlay\n");
 268                 err = -EINVAL;
 269                 goto out;
 270         }
 271
 272 #if 0
 273         Temporarily disable check so that old style overlay unittests
 274         do not fail when of_resolve_phandles() is moved into
 275         of_overlay_apply().
 276
 277         if (!of_node_check_flag(overlay, OF_DETACHED)) {
 278                 pr_err("overlay not detached\n");
 279                 err = -EINVAL;
 280                 goto out;
 281         }
 282 #endif
 283
 284         phandle_delta = live_tree_max_phandle() + 1;
 285         adjust_overlay_phandles(overlay, phandle_delta);
 286
 287         for_each_child_of_node(overlay, local_fixups)
 288                 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
 289                         break;
 290
 291         err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
 292         if (err)
 293                 goto out;
 294
 295         overlay_fixups = NULL;
 296
 297         for_each_child_of_node(overlay, child) {
 298                 if (!of_node_cmp(child->name, "__fixups__"))
 299                         overlay_fixups = child;
 300         }
 301
 302         if (!overlay_fixups) {
 303                 err = 0;
 304                 goto out;
 305         }
 306
 307         tree_symbols = of_find_node_by_path("/__symbols__");
 308         if (!tree_symbols) {
 309                 pr_err("no symbols in root of device tree.\n");
 310                 err = -EINVAL;
 311                 goto out;
 312         }
 313
 314         for_each_property_of_node(overlay_fixups, prop) {
 315
 316                 /* skip properties added automatically */
 317                 if (!of_prop_cmp(prop->name, "name"))
 318                         continue;
 319
 320                 err = of_property_read_string(tree_symbols,
 321                                 prop->name, &refpath);
 322                 if (err)
 323                         goto out;
 324
 325                 refnode = of_find_node_by_path(refpath);
 326                 if (!refnode) {
 327                         err = -ENOENT;
 328                         goto out;
 329                 }
 330
 331                 phandle = refnode->phandle;
 332                 of_node_put(refnode);
 333
 334                 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
 335                 if (err)
 336                         break;
 337         }
 338
 339 out:
 340         if (err)
 341                 pr_err("overlay phandle fixup failed: %d\n", err);
 342         of_node_put(tree_symbols);
 343
 344         return err;
 345 }
 346 EXPORT_SYMBOL_GPL(of_resolve_phandles);