lib/libfdt/fdt_overlay.c

   1 #include "libfdt_env.h"
   2
   3 #include <fdt.h>
   4 #include <libfdt.h>
   5
   6 #include "libfdt_internal.h"
   7
   8 /**
   9  * overlay_get_target_phandle - retrieves the target phandle of a fragment
  10  * @fdto: pointer to the device tree overlay blob
  11  * @fragment: node offset of the fragment in the overlay
  12  *
  13  * overlay_get_target_phandle() retrieves the target phandle of an
  14  * overlay fragment when that fragment uses a phandle (target
  15  * property) instead of a path (target-path property).
  16  *
  17  * returns:
  18  *      the phandle pointed by the target property
  19  *      0, if the phandle was not found
  20  *      -1, if the phandle was malformed
  21  */
  22 static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
  23 {
  24         const uint32_t *val;
  25         int len;
  26
  27         val = fdt_getprop(fdto, fragment, "target", &len);
  28         if (!val)
  29                 return 0;
  30
  31         if ((len != sizeof(*val)) || (*val == (uint32_t)-1))
  32                 return (uint32_t)-1;
  33
  34         return fdt32_to_cpu(*val);
  35 }
  36
  37 /**
  38  * overlay_get_target - retrieves the offset of a fragment's target
  39  * @fdt: Base device tree blob
  40  * @fdto: Device tree overlay blob
  41  * @fragment: node offset of the fragment in the overlay
  42  *
  43  * overlay_get_target() retrieves the target offset in the base
  44  * device tree of a fragment, no matter how the actual targetting is
  45  * done (through a phandle or a path)
  46  *
  47  * returns:
  48  *      the targetted node offset in the base device tree
  49  *      Negative error code on error
  50  */
  51 static int overlay_get_target(const void *fdt, const void *fdto,
  52                               int fragment)
  53 {
  54         uint32_t phandle;
  55         const char *path;
  56         int path_len;
  57
  58         /* Try first to do a phandle based lookup */
  59         phandle = overlay_get_target_phandle(fdto, fragment);
  60         if (phandle == (uint32_t)-1)
  61                 return -FDT_ERR_BADPHANDLE;
  62
  63         if (phandle)
  64                 return fdt_node_offset_by_phandle(fdt, phandle);
  65
  66         /* And then a path based lookup */
  67         path = fdt_getprop(fdto, fragment, "target-path", &path_len);
  68         if (!path) {
  69                 /*
  70                  * If we haven't found either a target or a
  71                  * target-path property in a node that contains a
  72                  * __overlay__ subnode (we wouldn't be called
  73                  * otherwise), consider it a improperly written
  74                  * overlay
  75                  */
  76                 if (path_len == -FDT_ERR_NOTFOUND)
  77                         return -FDT_ERR_BADOVERLAY;
  78
  79                 return path_len;
  80         }
  81
  82         return fdt_path_offset(fdt, path);
  83 }
  84
  85 /**
  86  * overlay_phandle_add_offset - Increases a phandle by an offset
  87  * @fdt: Base device tree blob
  88  * @node: Device tree overlay blob
  89  * @name: Name of the property to modify (phandle or linux,phandle)
  90  * @delta: offset to apply
  91  *
  92  * overlay_phandle_add_offset() increments a node phandle by a given
  93  * offset.
  94  *
  95  * returns:
  96  *      0 on success.
  97  *      Negative error code on error
  98  */
  99 static int overlay_phandle_add_offset(void *fdt, int node,
 100                                       const char *name, uint32_t delta)
 101 {
 102         const uint32_t *val;
 103         uint32_t adj_val;
 104         int len;
 105
 106         val = fdt_getprop(fdt, node, name, &len);
 107         if (!val)
 108                 return len;
 109
 110         if (len != sizeof(*val))
 111                 return -FDT_ERR_BADPHANDLE;
 112
 113         adj_val = fdt32_to_cpu(*val);
 114         if ((adj_val + delta) < adj_val)
 115                 return -FDT_ERR_NOPHANDLES;
 116
 117         adj_val += delta;
 118         if (adj_val == (uint32_t)-1)
 119                 return -FDT_ERR_NOPHANDLES;
 120
 121         return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
 122 }
 123
 124 /**
 125  * overlay_adjust_node_phandles - Offsets the phandles of a node
 126  * @fdto: Device tree overlay blob
 127  * @node: Offset of the node we want to adjust
 128  * @delta: Offset to shift the phandles of
 129  *
 130  * overlay_adjust_node_phandles() adds a constant to all the phandles
 131  * of a given node. This is mainly use as part of the overlay
 132  * application process, when we want to update all the overlay
 133  * phandles to not conflict with the overlays of the base device tree.
 134  *
 135  * returns:
 136  *      0 on success
 137  *      Negative error code on failure
 138  */
 139 static int overlay_adjust_node_phandles(void *fdto, int node,
 140                                         uint32_t delta)
 141 {
 142         int child;
 143         int ret;
 144
 145         ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
 146         if (ret && ret != -FDT_ERR_NOTFOUND)
 147                 return ret;
 148
 149         ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
 150         if (ret && ret != -FDT_ERR_NOTFOUND)
 151                 return ret;
 152
 153         fdt_for_each_subnode(child, fdto, node) {
 154                 ret = overlay_adjust_node_phandles(fdto, child, delta);
 155                 if (ret)
 156                         return ret;
 157         }
 158
 159         return 0;
 160 }
 161
 162 /**
 163  * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
 164  * @fdto: Device tree overlay blob
 165  * @delta: Offset to shift the phandles of
 166  *
 167  * overlay_adjust_local_phandles() adds a constant to all the
 168  * phandles of an overlay. This is mainly use as part of the overlay
 169  * application process, when we want to update all the overlay
 170  * phandles to not conflict with the overlays of the base device tree.
 171  *
 172  * returns:
 173  *      0 on success
 174  *      Negative error code on failure
 175  */
 176 static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
 177 {
 178         /*
 179          * Start adjusting the phandles from the overlay root
 180          */
 181         return overlay_adjust_node_phandles(fdto, 0, delta);
 182 }
 183
 184 /**
 185  * overlay_update_local_node_references - Adjust the overlay references
 186  * @fdto: Device tree overlay blob
 187  * @tree_node: Node offset of the node to operate on
 188  * @fixup_node: Node offset of the matching local fixups node
 189  * @delta: Offset to shift the phandles of
 190  *
 191  * overlay_update_local_nodes_references() update the phandles
 192  * pointing to a node within the device tree overlay by adding a
 193  * constant delta.
 194  *
 195  * This is mainly used as part of a device tree application process,
 196  * where you want the device tree overlays phandles to not conflict
 197  * with the ones from the base device tree before merging them.
 198  *
 199  * returns:
 200  *      0 on success
 201  *      Negative error code on failure
 202  */
 203 static int overlay_update_local_node_references(void *fdto,
 204                                                 int tree_node,
 205                                                 int fixup_node,
 206                                                 uint32_t delta)
 207 {
 208         int fixup_prop;
 209         int fixup_child;
 210         int ret;
 211
 212         fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
 213                 const uint32_t *fixup_val;
 214                 const char *tree_val;
 215                 const char *name;
 216                 int fixup_len;
 217                 int tree_len;
 218                 int i;
 219
 220                 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
 221                                                   &name, &fixup_len);
 222                 if (!fixup_val)
 223                         return fixup_len;
 224
 225                 if (fixup_len % sizeof(uint32_t))
 226                         return -FDT_ERR_BADOVERLAY;
 227
 228                 tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
 229                 if (!tree_val) {
 230                         if (tree_len == -FDT_ERR_NOTFOUND)
 231                                 return -FDT_ERR_BADOVERLAY;
 232
 233                         return tree_len;
 234                 }
 235
 236                 for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
 237                         uint32_t adj_val, poffset;
 238
 239                         poffset = fdt32_to_cpu(fixup_val[i]);
 240
 241                         /*
 242                          * phandles to fixup can be unaligned.
 243                          *
 244                          * Use a memcpy for the architectures that do
 245                          * not support unaligned accesses.
 246                          */
 247                         memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
 248
 249                         adj_val = fdt32_to_cpu(adj_val);
 250                         adj_val += delta;
 251                         adj_val = cpu_to_fdt32(adj_val);
 252
 253                         ret = fdt_setprop_inplace_namelen_partial(fdto,
 254                                                                   tree_node,
 255                                                                   name,
 256                                                                   strlen(name),
 257                                                                   poffset,
 258                                                                   &adj_val,
 259                                                                   sizeof(adj_val));
 260                         if (ret == -FDT_ERR_NOSPACE)
 261                                 return -FDT_ERR_BADOVERLAY;
 262
 263                         if (ret)
 264                                 return ret;
 265                 }
 266         }
 267
 268         fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
 269                 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
 270                                                             NULL);
 271                 int tree_child;
 272
 273                 tree_child = fdt_subnode_offset(fdto, tree_node,
 274                                                 fixup_child_name);
 275                 if (ret == -FDT_ERR_NOTFOUND)
 276                         return -FDT_ERR_BADOVERLAY;
 277                 if (tree_child < 0)
 278                         return tree_child;
 279
 280                 ret = overlay_update_local_node_references(fdto,
 281                                                            tree_child,
 282                                                            fixup_child,
 283                                                            delta);
 284                 if (ret)
 285                         return ret;
 286         }
 287
 288         return 0;
 289 }
 290
 291 /**
 292  * overlay_update_local_references - Adjust the overlay references
 293  * @fdto: Device tree overlay blob
 294  * @delta: Offset to shift the phandles of
 295  *
 296  * overlay_update_local_references() update all the phandles pointing
 297  * to a node within the device tree overlay by adding a constant
 298  * delta to not conflict with the base overlay.
 299  *
 300  * This is mainly used as part of a device tree application process,
 301  * where you want the device tree overlays phandles to not conflict
 302  * with the ones from the base device tree before merging them.
 303  *
 304  * returns:
 305  *      0 on success
 306  *      Negative error code on failure
 307  */
 308 static int overlay_update_local_references(void *fdto, uint32_t delta)
 309 {
 310         int fixups;
 311
 312         fixups = fdt_path_offset(fdto, "/__local_fixups__");
 313         if (fixups < 0) {
 314                 /* There's no local phandles to adjust, bail out */
 315                 if (fixups == -FDT_ERR_NOTFOUND)
 316                         return 0;
 317
 318                 return fixups;
 319         }
 320
 321         /*
 322          * Update our local references from the root of the tree
 323          */
 324         return overlay_update_local_node_references(fdto, 0, fixups,
 325                                                     delta);
 326 }
 327
 328 /**
 329  * overlay_fixup_one_phandle - Set an overlay phandle to the base one
 330  * @fdt: Base Device Tree blob
 331  * @fdto: Device tree overlay blob
 332  * @symbols_off: Node offset of the symbols node in the base device tree
 333  * @path: Path to a node holding a phandle in the overlay
 334  * @path_len: number of path characters to consider
 335  * @name: Name of the property holding the phandle reference in the overlay
 336  * @name_len: number of name characters to consider
 337  * @poffset: Offset within the overlay property where the phandle is stored
 338  * @label: Label of the node referenced by the phandle
 339  *
 340  * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
 341  * a node in the base device tree.
 342  *
 343  * This is part of the device tree overlay application process, when
 344  * you want all the phandles in the overlay to point to the actual
 345  * base dt nodes.
 346  *
 347  * returns:
 348  *      0 on success
 349  *      Negative error code on failure
 350  */
 351 static int overlay_fixup_one_phandle(void *fdt, void *fdto,
 352                                      int symbols_off,
 353                                      const char *path, uint32_t path_len,
 354                                      const char *name, uint32_t name_len,
 355                                      int poffset, const char *label)
 356 {
 357         const char *symbol_path;
 358         uint32_t phandle;
 359         int symbol_off, fixup_off;
 360         int prop_len;
 361
 362         symbol_path = fdt_getprop(fdt, symbols_off, label,
 363                                   &prop_len);
 364         if (!symbol_path)
 365                 return prop_len;
 366
 367         symbol_off = fdt_path_offset(fdt, symbol_path);
 368         if (symbol_off < 0)
 369                 return symbol_off;
 370
 371         phandle = fdt_get_phandle(fdt, symbol_off);
 372         if (!phandle)
 373                 return -FDT_ERR_NOTFOUND;
 374
 375         fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
 376         if (fixup_off == -FDT_ERR_NOTFOUND)
 377                 return -FDT_ERR_BADOVERLAY;
 378         if (fixup_off < 0)
 379                 return fixup_off;
 380
 381         phandle = cpu_to_fdt32(phandle);
 382         return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
 383                                                    name, name_len, poffset,
 384                                                    &phandle, sizeof(phandle));
 385 };
 386
 387 /**
 388  * overlay_fixup_phandle - Set an overlay phandle to the base one
 389  * @fdt: Base Device Tree blob
 390  * @fdto: Device tree overlay blob
 391  * @symbols_off: Node offset of the symbols node in the base device tree
 392  * @property: Property offset in the overlay holding the list of fixups
 393  *
 394  * overlay_fixup_phandle() resolves all the overlay phandles pointed
 395  * to in a __fixups__ property, and updates them to match the phandles
 396  * in use in the base device tree.
 397  *
 398  * This is part of the device tree overlay application process, when
 399  * you want all the phandles in the overlay to point to the actual
 400  * base dt nodes.
 401  *
 402  * returns:
 403  *      0 on success
 404  *      Negative error code on failure
 405  */
 406 static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
 407                                  int property)
 408 {
 409         const char *value;
 410         const char *label;
 411         int len;
 412
 413         value = fdt_getprop_by_offset(fdto, property,
 414                                       &label, &len);
 415         if (!value) {
 416                 if (len == -FDT_ERR_NOTFOUND)
 417                         return -FDT_ERR_INTERNAL;
 418
 419                 return len;
 420         }
 421
 422         do {
 423                 const char *path, *name, *fixup_end;
 424                 const char *fixup_str = value;
 425                 uint32_t path_len, name_len;
 426                 uint32_t fixup_len;
 427                 char *sep, *endptr;
 428                 int poffset, ret;
 429
 430                 fixup_end = memchr(value, '\0', len);
 431                 if (!fixup_end)
 432                         return -FDT_ERR_BADOVERLAY;
 433                 fixup_len = fixup_end - fixup_str;
 434
 435                 len -= fixup_len + 1;
 436                 value += fixup_len + 1;
 437
 438                 path = fixup_str;
 439                 sep = memchr(fixup_str, ':', fixup_len);
 440                 if (!sep || *sep != ':')
 441                         return -FDT_ERR_BADOVERLAY;
 442
 443                 path_len = sep - path;
 444                 if (path_len == (fixup_len - 1))
 445                         return -FDT_ERR_BADOVERLAY;
 446
 447                 fixup_len -= path_len + 1;
 448                 name = sep + 1;
 449                 sep = memchr(name, ':', fixup_len);
 450                 if (!sep || *sep != ':')
 451                         return -FDT_ERR_BADOVERLAY;
 452
 453                 name_len = sep - name;
 454                 if (!name_len)
 455                         return -FDT_ERR_BADOVERLAY;
 456
 457                 poffset = strtoul(sep + 1, &endptr, 10);
 458                 if ((*endptr != '\0') || (endptr <= (sep + 1)))
 459                         return -FDT_ERR_BADOVERLAY;
 460
 461                 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
 462                                                 path, path_len, name, name_len,
 463                                                 poffset, label);
 464                 if (ret)
 465                         return ret;
 466         } while (len > 0);
 467
 468         return 0;
 469 }
 470
 471 /**
 472  * overlay_fixup_phandles - Resolve the overlay phandles to the base
 473  *                          device tree
 474  * @fdt: Base Device Tree blob
 475  * @fdto: Device tree overlay blob
 476  *
 477  * overlay_fixup_phandles() resolves all the overlay phandles pointing
 478  * to nodes in the base device tree.
 479  *
 480  * This is one of the steps of the device tree overlay application
 481  * process, when you want all the phandles in the overlay to point to
 482  * the actual base dt nodes.
 483  *
 484  * returns:
 485  *      0 on success
 486  *      Negative error code on failure
 487  */
 488 static int overlay_fixup_phandles(void *fdt, void *fdto)
 489 {
 490         int fixups_off, symbols_off;
 491         int property;
 492
 493         /* We can have overlays without any fixups */
 494         fixups_off = fdt_path_offset(fdto, "/__fixups__");
 495         if ((fixups_off < 0 && (fixups_off != -FDT_ERR_NOTFOUND)))
 496                 return fixups_off;
 497
 498         /* And base DTs without symbols */
 499         symbols_off = fdt_path_offset(fdt, "/__symbols__");
 500         if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
 501                 return symbols_off;
 502
 503         fdt_for_each_property_offset(property, fdto, fixups_off) {
 504                 int ret;
 505
 506                 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
 507                 if (ret)
 508                         return ret;
 509         }
 510
 511         return 0;
 512 }
 513
 514 /**
 515  * overlay_apply_node - Merges a node into the base device tree
 516  * @fdt: Base Device Tree blob
 517  * @target: Node offset in the base device tree to apply the fragment to
 518  * @fdto: Device tree overlay blob
 519  * @node: Node offset in the overlay holding the changes to merge
 520  *
 521  * overlay_apply_node() merges a node into a target base device tree
 522  * node pointed.
 523  *
 524  * This is part of the final step in the device tree overlay
 525  * application process, when all the phandles have been adjusted and
 526  * resolved and you just have to merge overlay into the base device
 527  * tree.
 528  *
 529  * returns:
 530  *      0 on success
 531  *      Negative error code on failure
 532  */
 533 static int overlay_apply_node(void *fdt, int target,
 534                               void *fdto, int node)
 535 {
 536         int property;
 537         int subnode;
 538
 539         fdt_for_each_property_offset(property, fdto, node) {
 540                 const char *name;
 541                 const void *prop;
 542                 int prop_len;
 543                 int ret;
 544
 545                 prop = fdt_getprop_by_offset(fdto, property, &name,
 546                                              &prop_len);
 547                 if (prop_len == -FDT_ERR_NOTFOUND)
 548                         return -FDT_ERR_INTERNAL;
 549                 if (prop_len < 0)
 550                         return prop_len;
 551
 552                 ret = fdt_setprop(fdt, target, name, prop, prop_len);
 553                 if (ret)
 554                         return ret;
 555         }
 556
 557         fdt_for_each_subnode(subnode, fdto, node) {
 558                 const char *name = fdt_get_name(fdto, subnode, NULL);
 559                 int nnode;
 560                 int ret;
 561
 562                 nnode = fdt_add_subnode(fdt, target, name);
 563                 if (nnode == -FDT_ERR_EXISTS) {
 564                         nnode = fdt_subnode_offset(fdt, target, name);
 565                         if (nnode == -FDT_ERR_NOTFOUND)
 566                                 return -FDT_ERR_INTERNAL;
 567                 }
 568
 569                 if (nnode < 0)
 570                         return nnode;
 571
 572                 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
 573                 if (ret)
 574                         return ret;
 575         }
 576
 577         return 0;
 578 }
 579
 580 /**
 581  * overlay_merge - Merge an overlay into its base device tree
 582  * @fdt: Base Device Tree blob
 583  * @fdto: Device tree overlay blob
 584  *
 585  * overlay_merge() merges an overlay into its base device tree.
 586  *
 587  * This is the final step in the device tree overlay application
 588  * process, when all the phandles have been adjusted and resolved and
 589  * you just have to merge overlay into the base device tree.
 590  *
 591  * returns:
 592  *      0 on success
 593  *      Negative error code on failure
 594  */
 595 static int overlay_merge(void *fdt, void *fdto)
 596 {
 597         int fragment;
 598
 599         fdt_for_each_subnode(fragment, fdto, 0) {
 600                 int overlay;
 601                 int target;
 602                 int ret;
 603
 604                 /*
 605                  * Each fragments will have an __overlay__ node. If
 606                  * they don't, it's not supposed to be merged
 607                  */
 608                 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
 609                 if (overlay == -FDT_ERR_NOTFOUND)
 610                         continue;
 611
 612                 if (overlay < 0)
 613                         return overlay;
 614
 615                 target = overlay_get_target(fdt, fdto, fragment);
 616                 if (target < 0)
 617                         return target;
 618
 619                 ret = overlay_apply_node(fdt, target, fdto, overlay);
 620                 if (ret)
 621                         return ret;
 622         }
 623
 624         return 0;
 625 }
 626
 627 int fdt_overlay_apply(void *fdt, void *fdto)
 628 {
 629         uint32_t delta = fdt_get_max_phandle(fdt);
 630         int ret;
 631
 632         FDT_CHECK_HEADER(fdt);
 633         FDT_CHECK_HEADER(fdto);
 634
 635         ret = overlay_adjust_local_phandles(fdto, delta);
 636         if (ret)
 637                 goto err;
 638
 639         ret = overlay_update_local_references(fdto, delta);
 640         if (ret)
 641                 goto err;
 642
 643         ret = overlay_fixup_phandles(fdt, fdto);
 644         if (ret)
 645                 goto err;
 646
 647         ret = overlay_merge(fdt, fdto);
 648         if (ret)
 649                 goto err;
 650
 651         /*
 652          * The overlay has been damaged, erase its magic.
 653          */
 654         fdt_set_magic(fdto, ~0);
 655
 656         return 0;
 657
 658 err:
 659         /*
 660          * The overlay might have been damaged, erase its magic.
 661          */
 662         fdt_set_magic(fdto, ~0);
 663
 664         /*
 665          * The base device tree might have been damaged, erase its
 666          * magic.
 667          */
 668         fdt_set_magic(fdt, ~0);
 669
 670         return ret;
 671 }