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/string.h>
  22 #include <linux/slab.h>
  23
  24 /* illegal phandle value (set when unresolved) */
  25 #define OF_PHANDLE_ILLEGAL      0xdeadbeef
  26
  27 /**
  28  * Find a node with the give full name by recursively following any of
  29  * the child node links.
  30  */
  31 static struct device_node *find_node_by_full_name(struct device_node *node,
  32                 const char *full_name)
  33 {
  34         struct device_node *child, *found;
  35
  36         if (!node)
  37                 return NULL;
  38
  39         if (!of_node_cmp(node->full_name, full_name))
  40                 return of_node_get(node);
  41
  42         for_each_child_of_node(node, child) {
  43                 found = find_node_by_full_name(child, full_name);
  44                 if (found != NULL) {
  45                         of_node_put(child);
  46                         return found;
  47                 }
  48         }
  49
  50         return NULL;
  51 }
  52
  53 static phandle live_tree_max_phandle(void)
  54 {
  55         struct device_node *node;
  56         phandle phandle;
  57         unsigned long flags;
  58
  59         raw_spin_lock_irqsave(&devtree_lock, flags);
  60         phandle = 0;
  61         for_each_of_allnodes(node) {
  62                 if (node->phandle != OF_PHANDLE_ILLEGAL &&
  63                                 node->phandle > phandle)
  64                         phandle = node->phandle;
  65         }
  66         raw_spin_unlock_irqrestore(&devtree_lock, flags);
  67
  68         return phandle;
  69 }
  70
  71 static void adjust_overlay_phandles(struct device_node *overlay,
  72                 int phandle_delta)
  73 {
  74         struct device_node *child;
  75         struct property *prop;
  76         phandle phandle;
  77
  78         /* adjust node's phandle in node */
  79         if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
  80                 overlay->phandle += phandle_delta;
  81
  82         /* copy adjusted phandle into *phandle properties */
  83         for_each_property_of_node(overlay, prop) {
  84
  85                 if (of_prop_cmp(prop->name, "phandle") &&
  86                     of_prop_cmp(prop->name, "linux,phandle"))
  87                         continue;
  88
  89                 if (prop->length < 4)
  90                         continue;
  91
  92                 phandle = be32_to_cpup(prop->value);
  93                 if (phandle == OF_PHANDLE_ILLEGAL)
  94                         continue;
  95
  96                 *(uint32_t *)prop->value = cpu_to_be32(overlay->phandle);
  97         }
  98
  99         for_each_child_of_node(overlay, child)
 100                 adjust_overlay_phandles(child, phandle_delta);
 101 }
 102
 103 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
 104                 struct property *prop_fixup, phandle phandle)
 105 {
 106         struct device_node *refnode;
 107         struct property *prop;
 108         char *value, *cur, *end, *node_path, *prop_name, *s;
 109         int offset, len;
 110         int err = 0;
 111
 112         value = kmalloc(prop_fixup->length, GFP_KERNEL);
 113         if (!value)
 114                 return -ENOMEM;
 115         memcpy(value, prop_fixup->value, prop_fixup->length);
 116
 117         /* prop_fixup contains a list of tuples of path:property_name:offset */
 118         end = value + prop_fixup->length;
 119         for (cur = value; cur < end; cur += len + 1) {
 120                 len = strlen(cur);
 121
 122                 node_path = cur;
 123                 s = strchr(cur, ':');
 124                 if (!s) {
 125                         err = -EINVAL;
 126                         goto err_fail;
 127                 }
 128                 *s++ = '\0';
 129
 130                 prop_name = s;
 131                 s = strchr(s, ':');
 132                 if (!s) {
 133                         err = -EINVAL;
 134                         goto err_fail;
 135                 }
 136                 *s++ = '\0';
 137
 138                 err = kstrtoint(s, 10, &offset);
 139                 if (err)
 140                         goto err_fail;
 141
 142                 refnode = find_node_by_full_name(overlay, node_path);
 143                 if (!refnode)
 144                         continue;
 145
 146                 for_each_property_of_node(refnode, prop) {
 147                         if (!of_prop_cmp(prop->name, prop_name))
 148                                 break;
 149                 }
 150                 of_node_put(refnode);
 151
 152                 if (!prop) {
 153                         err = -ENOENT;
 154                         goto err_fail;
 155                 }
 156
 157                 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
 158         }
 159
 160 err_fail:
 161         kfree(value);
 162         return err;
 163 }
 164
 165 /* compare nodes taking into account that 'name' strips out the @ part */
 166 static int node_name_cmp(const struct device_node *dn1,
 167                 const struct device_node *dn2)
 168 {
 169         const char *n1 = strrchr(dn1->full_name, '/') ? : "/";
 170         const char *n2 = strrchr(dn2->full_name, '/') ? : "/";
 171
 172         return of_node_cmp(n1, n2);
 173 }
 174
 175 /*
 176  * Adjust the local phandle references by the given phandle delta.
 177  *
 178  * Subtree @local_fixups, which is overlay node __local_fixups__,
 179  * mirrors the fragment node structure at the root of the overlay.
 180  *
 181  * For each property in the fragments that contains a phandle reference,
 182  * @local_fixups has a property of the same name that contains a list
 183  * of offsets of the phandle reference(s) within the respective property
 184  * value(s).  The values at these offsets will be fixed up.
 185  */
 186 static int adjust_local_phandle_references(struct device_node *local_fixups,
 187                 struct device_node *overlay, int phandle_delta)
 188 {
 189         struct device_node *child, *overlay_child;
 190         struct property *prop_fix, *prop;
 191         int err, i, count;
 192         unsigned int off;
 193         phandle phandle;
 194
 195         if (!local_fixups)
 196                 return 0;
 197
 198         for_each_property_of_node(local_fixups, prop_fix) {
 199
 200                 /* skip properties added automatically */
 201                 if (!of_prop_cmp(prop_fix->name, "name") ||
 202                     !of_prop_cmp(prop_fix->name, "phandle") ||
 203                     !of_prop_cmp(prop_fix->name, "linux,phandle"))
 204                         continue;
 205
 206                 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
 207                         return -EINVAL;
 208                 count = prop_fix->length / sizeof(__be32);
 209
 210                 for_each_property_of_node(overlay, prop) {
 211                         if (!of_prop_cmp(prop->name, prop_fix->name))
 212                                 break;
 213                 }
 214
 215                 if (!prop)
 216                         return -EINVAL;
 217
 218                 for (i = 0; i < count; i++) {
 219                         off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
 220                         if ((off + 4) > prop->length)
 221                                 return -EINVAL;
 222
 223                         phandle = be32_to_cpu(*(__be32 *)(prop->value + off));
 224                         phandle += phandle_delta;
 225                         *(__be32 *)(prop->value + off) = cpu_to_be32(phandle);
 226                 }
 227         }
 228
 229         /*
 230          * These nested loops recurse down two subtrees in parallel, where the
 231          * node names in the two subtrees match.
 232          *
 233          * The roots of the subtrees are the overlay's __local_fixups__ node
 234          * and the overlay's root node.
 235          */
 236         for_each_child_of_node(local_fixups, child) {
 237
 238                 for_each_child_of_node(overlay, overlay_child)
 239                         if (!node_name_cmp(child, overlay_child))
 240                                 break;
 241
 242                 if (!overlay_child)
 243                         return -EINVAL;
 244
 245                 err = adjust_local_phandle_references(child, overlay_child,
 246                                 phandle_delta);
 247                 if (err)
 248                         return err;
 249         }
 250
 251         return 0;
 252 }
 253
 254 /**
 255  * of_resolve_phandles - Relocate and resolve overlay against live tree
 256  *
 257  * @overlay:    Pointer to devicetree overlay to relocate and resolve
 258  *
 259  * Modify (relocate) values of local phandles in @overlay to a range that
 260  * does not conflict with the live expanded devicetree.  Update references
 261  * to the local phandles in @overlay.  Update (resolve) phandle references
 262  * in @overlay that refer to the live expanded devicetree.
 263  *
 264  * Phandle values in the live tree are in the range of
 265  * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
 266  * also begin with at 1.  Adjust the phandle values in the overlay to begin
 267  * at live_tree_max_phandle() + 1.  Update references to the phandles to
 268  * the adjusted phandle values.
 269  *
 270  * The name of each property in the "__fixups__" node in the overlay matches
 271  * the name of a symbol (a label) in the live tree.  The values of each
 272  * property in the "__fixups__" node is a list of the property values in the
 273  * overlay that need to be updated to contain the phandle reference
 274  * corresponding to that symbol in the live tree.  Update the references in
 275  * the overlay with the phandle values in the live tree.
 276  *
 277  * @overlay must be detached.
 278  *
 279  * Resolving and applying @overlay to the live expanded devicetree must be
 280  * protected by a mechanism to ensure that multiple overlays are processed
 281  * in a single threaded manner so that multiple overlays will not relocate
 282  * phandles to overlapping ranges.  The mechanism to enforce this is not
 283  * yet implemented.
 284  *
 285  * Return: %0 on success or a negative error value on error.
 286  */
 287 int of_resolve_phandles(struct device_node *overlay)
 288 {
 289         struct device_node *child, *local_fixups, *refnode;
 290         struct device_node *tree_symbols, *overlay_fixups;
 291         struct property *prop;
 292         const char *refpath;
 293         phandle phandle, phandle_delta;
 294         int err;
 295
 296         tree_symbols = NULL;
 297
 298         if (!overlay) {
 299                 pr_err("null overlay\n");
 300                 err = -EINVAL;
 301                 goto out;
 302         }
 303         if (!of_node_check_flag(overlay, OF_DETACHED)) {
 304                 pr_err("overlay not detached\n");
 305                 err = -EINVAL;
 306                 goto out;
 307         }
 308
 309         phandle_delta = live_tree_max_phandle() + 1;
 310         adjust_overlay_phandles(overlay, phandle_delta);
 311
 312         for_each_child_of_node(overlay, local_fixups)
 313                 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
 314                         break;
 315
 316         err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
 317         if (err)
 318                 goto out;
 319
 320         overlay_fixups = NULL;
 321
 322         for_each_child_of_node(overlay, child) {
 323                 if (!of_node_cmp(child->name, "__fixups__"))
 324                         overlay_fixups = child;
 325         }
 326
 327         if (!overlay_fixups) {
 328                 err = 0;
 329                 goto out;
 330         }
 331
 332         tree_symbols = of_find_node_by_path("/__symbols__");
 333         if (!tree_symbols) {
 334                 pr_err("no symbols in root of device tree.\n");
 335                 err = -EINVAL;
 336                 goto out;
 337         }
 338
 339         for_each_property_of_node(overlay_fixups, prop) {
 340
 341                 /* skip properties added automatically */
 342                 if (!of_prop_cmp(prop->name, "name"))
 343                         continue;
 344
 345                 err = of_property_read_string(tree_symbols,
 346                                 prop->name, &refpath);
 347                 if (err)
 348                         goto out;
 349
 350                 refnode = of_find_node_by_path(refpath);
 351                 if (!refnode) {
 352                         err = -ENOENT;
 353                         goto out;
 354                 }
 355
 356                 phandle = refnode->phandle;
 357                 of_node_put(refnode);
 358
 359                 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
 360                 if (err)
 361                         break;
 362         }
 363
 364 out:
 365         if (err)
 366                 pr_err("overlay phandle fixup failed: %d\n", err);
 367         of_node_put(tree_symbols);
 368
 369         return err;
 370 }
 371 EXPORT_SYMBOL_GPL(of_resolve_phandles);