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 /* illegal phandle value (set when unresolved) */
  24 #define OF_PHANDLE_ILLEGAL      0xdeadbeef
  25
  26 /**
  27  * Find a node with the give full name by recursively following any of
  28  * the child node links.
  29  */
  30 static struct device_node *find_node_by_full_name(struct device_node *node,
  31                 const char *full_name)
  32 {
  33         struct device_node *child, *found;
  34
  35         if (!node)
  36                 return NULL;
  37
  38         if (!of_node_cmp(node->full_name, full_name))
  39                 return of_node_get(node);
  40
  41         for_each_child_of_node(node, child) {
  42                 found = find_node_by_full_name(child, full_name);
  43                 if (found != NULL) {
  44                         of_node_put(child);
  45                         return found;
  46                 }
  47         }
  48
  49         return NULL;
  50 }
  51
  52 static phandle live_tree_max_phandle(void)
  53 {
  54         struct device_node *node;
  55         phandle phandle;
  56         unsigned long flags;
  57
  58         raw_spin_lock_irqsave(&devtree_lock, flags);
  59         phandle = 0;
  60         for_each_of_allnodes(node) {
  61                 if (node->phandle != OF_PHANDLE_ILLEGAL &&
  62                                 node->phandle > phandle)
  63                         phandle = node->phandle;
  64         }
  65         raw_spin_unlock_irqrestore(&devtree_lock, flags);
  66
  67         return phandle;
  68 }
  69
  70 static void adjust_overlay_phandles(struct device_node *overlay,
  71                 int phandle_delta)
  72 {
  73         struct device_node *child;
  74         struct property *prop;
  75         phandle phandle;
  76
  77         /* adjust node's phandle in node */
  78         if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
  79                 overlay->phandle += phandle_delta;
  80
  81         /* copy adjusted phandle into *phandle properties */
  82         for_each_property_of_node(overlay, prop) {
  83
  84                 if (of_prop_cmp(prop->name, "phandle") &&
  85                     of_prop_cmp(prop->name, "linux,phandle"))
  86                         continue;
  87
  88                 if (prop->length < 4)
  89                         continue;
  90
  91                 phandle = be32_to_cpup(prop->value);
  92                 if (phandle == OF_PHANDLE_ILLEGAL)
  93                         continue;
  94
  95                 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
  96         }
  97
  98         for_each_child_of_node(overlay, child)
  99                 adjust_overlay_phandles(child, phandle_delta);
 100 }
 101
 102 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
 103                 struct property *prop_fixup, phandle phandle)
 104 {
 105         struct device_node *refnode;
 106         struct property *prop;
 107         char *value, *cur, *end, *node_path, *prop_name, *s;
 108         int offset, len;
 109         int err = 0;
 110
 111         value = kmalloc(prop_fixup->length, GFP_KERNEL);
 112         if (!value)
 113                 return -ENOMEM;
 114         memcpy(value, prop_fixup->value, prop_fixup->length);
 115
 116         /* prop_fixup contains a list of tuples of path:property_name:offset */
 117         end = value + prop_fixup->length;
 118         for (cur = value; cur < end; cur += len + 1) {
 119                 len = strlen(cur);
 120
 121                 node_path = cur;
 122                 s = strchr(cur, ':');
 123                 if (!s) {
 124                         err = -EINVAL;
 125                         goto err_fail;
 126                 }
 127                 *s++ = '\0';
 128
 129                 prop_name = s;
 130                 s = strchr(s, ':');
 131                 if (!s) {
 132                         err = -EINVAL;
 133                         goto err_fail;
 134                 }
 135                 *s++ = '\0';
 136
 137                 err = kstrtoint(s, 10, &offset);
 138                 if (err)
 139                         goto err_fail;
 140
 141                 refnode = find_node_by_full_name(overlay, node_path);
 142                 if (!refnode)
 143                         continue;
 144
 145                 for_each_property_of_node(refnode, prop) {
 146                         if (!of_prop_cmp(prop->name, prop_name))
 147                                 break;
 148                 }
 149                 of_node_put(refnode);
 150
 151                 if (!prop) {
 152                         err = -ENOENT;
 153                         goto err_fail;
 154                 }
 155
 156                 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
 157         }
 158
 159 err_fail:
 160         kfree(value);
 161         return err;
 162 }
 163
 164 /* compare nodes taking into account that 'name' strips out the @ part */
 165 static int node_name_cmp(const struct device_node *dn1,
 166                 const struct device_node *dn2)
 167 {
 168         const char *n1 = strrchr(dn1->full_name, '/') ? : "/";
 169         const char *n2 = strrchr(dn2->full_name, '/') ? : "/";
 170
 171         return of_node_cmp(n1, n2);
 172 }
 173
 174 /*
 175  * Adjust the local phandle references by the given phandle delta.
 176  *
 177  * Subtree @local_fixups, which is overlay node __local_fixups__,
 178  * mirrors the fragment node structure at the root of the overlay.
 179  *
 180  * For each property in the fragments that contains a phandle reference,
 181  * @local_fixups has a property of the same name that contains a list
 182  * of offsets of the phandle reference(s) within the respective property
 183  * value(s).  The values at these offsets will be fixed up.
 184  */
 185 static int adjust_local_phandle_references(struct device_node *local_fixups,
 186                 struct device_node *overlay, int phandle_delta)
 187 {
 188         struct device_node *child, *overlay_child;
 189         struct property *prop_fix, *prop;
 190         int err, i, count;
 191         unsigned int off;
 192         phandle phandle;
 193
 194         if (!local_fixups)
 195                 return 0;
 196
 197         for_each_property_of_node(local_fixups, prop_fix) {
 198
 199                 /* skip properties added automatically */
 200                 if (!of_prop_cmp(prop_fix->name, "name") ||
 201                     !of_prop_cmp(prop_fix->name, "phandle") ||
 202                     !of_prop_cmp(prop_fix->name, "linux,phandle"))
 203                         continue;
 204
 205                 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
 206                         return -EINVAL;
 207                 count = prop_fix->length / sizeof(__be32);
 208
 209                 for_each_property_of_node(overlay, prop) {
 210                         if (!of_prop_cmp(prop->name, prop_fix->name))
 211                                 break;
 212                 }
 213
 214                 if (!prop)
 215                         return -EINVAL;
 216
 217                 for (i = 0; i < count; i++) {
 218                         off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
 219                         if ((off + 4) > prop->length)
 220                                 return -EINVAL;
 221
 222                         phandle = be32_to_cpu(*(__be32 *)(prop->value + off));
 223                         phandle += phandle_delta;
 224                         *(__be32 *)(prop->value + off) = cpu_to_be32(phandle);
 225                 }
 226         }
 227
 228         /*
 229          * These nested loops recurse down two subtrees in parallel, where the
 230          * node names in the two subtrees match.
 231          *
 232          * The roots of the subtrees are the overlay's __local_fixups__ node
 233          * and the overlay's root node.
 234          */
 235         for_each_child_of_node(local_fixups, child) {
 236
 237                 for_each_child_of_node(overlay, overlay_child)
 238                         if (!node_name_cmp(child, overlay_child))
 239                                 break;
 240
 241                 if (!overlay_child)
 242                         return -EINVAL;
 243
 244                 err = adjust_local_phandle_references(child, overlay_child,
 245                                 phandle_delta);
 246                 if (err)
 247                         return err;
 248         }
 249
 250         return 0;
 251 }
 252
 253 /**
 254  * of_resolve_phandles - Relocate and resolve overlay against live tree
 255  *
 256  * @overlay:    Pointer to devicetree overlay to relocate and resolve
 257  *
 258  * Modify (relocate) values of local phandles in @overlay to a range that
 259  * does not conflict with the live expanded devicetree.  Update references
 260  * to the local phandles in @overlay.  Update (resolve) phandle references
 261  * in @overlay that refer to the live expanded devicetree.
 262  *
 263  * Phandle values in the live tree are in the range of
 264  * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
 265  * also begin with at 1.  Adjust the phandle values in the overlay to begin
 266  * at live_tree_max_phandle() + 1.  Update references to the phandles to
 267  * the adjusted phandle values.
 268  *
 269  * The name of each property in the "__fixups__" node in the overlay matches
 270  * the name of a symbol (a label) in the live tree.  The values of each
 271  * property in the "__fixups__" node is a list of the property values in the
 272  * overlay that need to be updated to contain the phandle reference
 273  * corresponding to that symbol in the live tree.  Update the references in
 274  * the overlay with the phandle values in the live tree.
 275  *
 276  * @overlay must be detached.
 277  *
 278  * Resolving and applying @overlay to the live expanded devicetree must be
 279  * protected by a mechanism to ensure that multiple overlays are processed
 280  * in a single threaded manner so that multiple overlays will not relocate
 281  * phandles to overlapping ranges.  The mechanism to enforce this is not
 282  * yet implemented.
 283  *
 284  * Return: %0 on success or a negative error value on error.
 285  */
 286 int of_resolve_phandles(struct device_node *overlay)
 287 {
 288         struct device_node *child, *local_fixups, *refnode;
 289         struct device_node *tree_symbols, *overlay_fixups;
 290         struct property *prop;
 291         const char *refpath;
 292         phandle phandle, phandle_delta;
 293         int err;
 294
 295         tree_symbols = NULL;
 296
 297         if (!overlay) {
 298                 pr_err("null overlay\n");
 299                 err = -EINVAL;
 300                 goto out;
 301         }
 302         if (!of_node_check_flag(overlay, OF_DETACHED)) {
 303                 pr_err("overlay not detached\n");
 304                 err = -EINVAL;
 305                 goto out;
 306         }
 307
 308         phandle_delta = live_tree_max_phandle() + 1;
 309         adjust_overlay_phandles(overlay, phandle_delta);
 310
 311         for_each_child_of_node(overlay, local_fixups)
 312                 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
 313                         break;
 314
 315         err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
 316         if (err)
 317                 goto out;
 318
 319         overlay_fixups = NULL;
 320
 321         for_each_child_of_node(overlay, child) {
 322                 if (!of_node_cmp(child->name, "__fixups__"))
 323                         overlay_fixups = child;
 324         }
 325
 326         if (!overlay_fixups) {
 327                 err = 0;
 328                 goto out;
 329         }
 330
 331         tree_symbols = of_find_node_by_path("/__symbols__");
 332         if (!tree_symbols) {
 333                 pr_err("no symbols in root of device tree.\n");
 334                 err = -EINVAL;
 335                 goto out;
 336         }
 337
 338         for_each_property_of_node(overlay_fixups, prop) {
 339
 340                 /* skip properties added automatically */
 341                 if (!of_prop_cmp(prop->name, "name"))
 342                         continue;
 343
 344                 err = of_property_read_string(tree_symbols,
 345                                 prop->name, &refpath);
 346                 if (err)
 347                         goto out;
 348
 349                 refnode = of_find_node_by_path(refpath);
 350                 if (!refnode) {
 351                         err = -ENOENT;
 352                         goto out;
 353                 }
 354
 355                 phandle = refnode->phandle;
 356                 of_node_put(refnode);
 357
 358                 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
 359                 if (err)
 360                         break;
 361         }
 362
 363 out:
 364         if (err)
 365                 pr_err("overlay phandle fixup failed: %d\n", err);
 366         of_node_put(tree_symbols);
 367
 368         return err;
 369 }
 370 EXPORT_SYMBOL_GPL(of_resolve_phandles);