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