1 // SPDX-License-Identifier: GPL-2.0+ OR BSD-2-Clause
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2013 Google, Inc
5 * Written by Simon Glass <sjg@chromium.org>
8 #include <linux/libfdt_env.h>
12 #include <linux/libfdt.h>
17 #define FDT_MAX_DEPTH 32
19 static int str_in_list(const char *str, char * const list[], int count)
23 for (i = 0; i < count; i++)
24 if (!strcmp(list[i], str))
30 int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
31 char * const exc_prop[], int exc_prop_count,
32 struct fdt_region region[], int max_regions,
33 char *path, int path_len, int add_string_tab)
35 int stack[FDT_MAX_DEPTH] = { 0 };
43 int base = fdt_off_dt_struct(fdt);
48 const struct fdt_property *prop;
57 tag = fdt_next_tag(fdt, offset, &nextoffset);
64 prop = fdt_get_property_by_offset(fdt, offset, NULL);
65 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
66 if (str_in_list(str, exc_prop, exc_prop_count))
77 if (depth == FDT_MAX_DEPTH)
78 return -FDT_ERR_BADSTRUCTURE;
79 name = fdt_get_name(fdt, offset, &len);
80 if (end - path + 2 + len >= path_len)
81 return -FDT_ERR_NOSPACE;
89 if (str_in_list(path, inc, inc_count))
99 /* Depth must never go below -1 */
101 return -FDT_ERR_BADSTRUCTURE;
103 want = stack[depth--];
104 while (end > path && *--end != '/')
114 if (include && start == -1) {
115 /* Should we merge with previous? */
116 if (count && count <= max_regions &&
117 offset == region[count - 1].offset +
118 region[count - 1].size - base)
119 start = region[--count].offset - base;
124 if (!include && start != -1) {
125 if (count < max_regions) {
126 region[count].offset = base + start;
127 region[count].size = stop_at - start;
132 } while (tag != FDT_END);
134 if (nextoffset != fdt_size_dt_struct(fdt))
135 return -FDT_ERR_BADLAYOUT;
137 /* Add a region for the END tag and the string table */
138 if (count < max_regions) {
139 region[count].offset = base + start;
140 region[count].size = nextoffset - start;
142 region[count].size += fdt_size_dt_strings(fdt);
150 * fdt_add_region() - Add a new region to our list
151 * @info: State information
152 * @offset: Start offset of region
153 * @size: Size of region
155 * The region is added if there is space, but in any case we increment the
156 * count. If permitted, and the new region overlaps the last one, we merge
159 static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
161 struct fdt_region *reg;
163 reg = info->region ? &info->region[info->count - 1] : NULL;
164 if (info->can_merge && info->count &&
165 info->count <= info->max_regions &&
166 reg && offset <= reg->offset + reg->size) {
167 reg->size = offset + size - reg->offset;
168 } else if (info->count++ < info->max_regions) {
171 reg->offset = offset;
181 static int region_list_contains_offset(struct fdt_region_state *info,
182 const void *fdt, int target)
184 struct fdt_region *reg;
187 target += fdt_off_dt_struct(fdt);
188 for (reg = info->region, num = 0; num < info->count; reg++, num++) {
189 if (target >= reg->offset && target < reg->offset + reg->size)
197 * fdt_add_alias_regions() - Add regions covering the aliases that we want
199 * The /aliases node is not automatically included by fdtgrep unless the
200 * command-line arguments cause to be included (or not excluded). However
201 * aliases are special in that we generally want to include those which
202 * reference a node that fdtgrep includes.
204 * In fact we want to include only aliases for those nodes still included in
205 * the fdt, and drop the other aliases since they point to nodes that will not
208 * This function scans the aliases and adds regions for those which we want
211 * @fdt: Device tree to scan
212 * @region: List of regions
213 * @count: Number of regions in the list so far (i.e. starting point for this
215 * @max_regions: Maximum number of regions in @region list
216 * @info: Place to put the region state
217 * @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
218 * not have enough room in the regions table for the regions we wanted to add.
220 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
221 int max_regions, struct fdt_region_state *info)
223 int base = fdt_off_dt_struct(fdt);
224 int node, node_end, offset;
225 int did_alias_header;
227 node = fdt_subnode_offset(fdt, 0, "aliases");
229 return -FDT_ERR_NOTFOUND;
232 * Find the next node so that we know where the /aliases node ends. We
233 * need special handling if /aliases is the last node.
235 node_end = fdt_next_subnode(fdt, node);
236 if (node_end == -FDT_ERR_NOTFOUND)
237 /* Move back to the FDT_END_NODE tag of '/' */
238 node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
239 else if (node_end < 0) /* other error */
241 node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
243 did_alias_header = 0;
244 info->region = region;
247 info->max_regions = max_regions;
249 for (offset = fdt_first_property_offset(fdt, node);
251 offset = fdt_next_property_offset(fdt, offset)) {
252 const struct fdt_property *prop;
256 prop = fdt_get_property_by_offset(fdt, offset, NULL);
257 name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
258 target = fdt_path_offset(fdt, name);
259 if (!region_list_contains_offset(info, fdt, target))
261 next = fdt_next_property_offset(fdt, offset);
265 if (!did_alias_header) {
266 fdt_add_region(info, base + node, 12);
267 did_alias_header = 1;
269 fdt_add_region(info, base + offset, next - offset);
272 /* Add the FDT_END_NODE tag */
273 if (did_alias_header)
274 fdt_add_region(info, base + node_end, sizeof(fdt32_t));
276 return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
280 * fdt_include_supernodes() - Include supernodes required by this node
281 * @info: State information
282 * @depth: Current stack depth
284 * When we decided to include a node or property which is not at the top
285 * level, this function forces the inclusion of higher level nodes. For
286 * example, given this tree:
293 * If we decide to include testing then we need the root node to have a valid
294 * tree. This function adds those regions.
296 static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
298 int base = fdt_off_dt_struct(info->fdt);
303 * Work down the stack looking for supernodes that we didn't include.
304 * The algortihm here is actually pretty simple, since we know that
305 * no previous subnode had to include these nodes, or if it did, we
306 * marked them as included (on the stack) already.
308 for (i = 0; i <= depth; i++) {
309 if (!info->stack[i].included) {
310 start = info->stack[i].offset;
312 /* Add the FDT_BEGIN_NODE tag of this supernode */
313 fdt_next_tag(info->fdt, start, &stop_at);
314 if (fdt_add_region(info, base + start, stop_at - start))
317 /* Remember that this supernode is now included */
318 info->stack[i].included = 1;
322 /* Force (later) generation of the FDT_END_NODE tag */
323 if (!info->stack[i].want)
324 info->stack[i].want = WANT_NODES_ONLY;
339 int fdt_first_region(const void *fdt,
340 int (*h_include)(void *priv, const void *fdt, int offset,
341 int type, const char *data, int size),
342 void *priv, struct fdt_region *region,
343 char *path, int path_len, int flags,
344 struct fdt_region_state *info)
346 struct fdt_region_ptrs *p = &info->ptrs;
348 /* Set up our state */
351 info->max_regions = 1;
353 p->want = WANT_NOTHING;
358 p->done = FDT_DONE_NOTHING;
360 return fdt_next_region(fdt, h_include, priv, region,
361 path, path_len, flags, info);
364 /***********************************************************************
366 * Theory of operation
368 * Note: in this description 'included' means that a node (or other part
369 * of the tree) should be included in the region list, i.e. it will have
370 * a region which covers its part of the tree.
372 * This function maintains some state from the last time it is called.
373 * It checks the next part of the tree that it is supposed to look at
374 * (p.nextoffset) to see if that should be included or not. When it
375 * finds something to include, it sets info->start to its offset. This
376 * marks the start of the region we want to include.
378 * Once info->start is set to the start (i.e. not -1), we continue
379 * scanning until we find something that we don't want included. This
380 * will be the end of a region. At this point we can close off the
381 * region and add it to the list. So we do so, and reset info->start
384 * One complication here is that we want to merge regions. So when we
385 * come to add another region later, we may in fact merge it with the
386 * previous one if one ends where the other starts.
388 * The function fdt_add_region() will return -1 if it fails to add the
389 * region, because we already have a region ready to be returned, and
390 * the new one cannot be merged in with it. In this case, we must return
391 * the region we found, and wait for another call to this function.
392 * When it comes, we will repeat the processing of the tag and again
393 * try to add a region. This time it will succeed.
395 * The current state of the pointers (stack, offset, etc.) is maintained
396 * in a ptrs member. At the start of every loop iteration we make a copy
397 * of it. The copy is then updated as the tag is processed. Only if we
398 * get to the end of the loop iteration (and successfully call
399 * fdt_add_region() if we need to) can we commit the changes we have
400 * made to these pointers. For example, if we see an FDT_END_NODE tag,
401 * we will decrement the depth value. But if we need to add a region
402 * for this tag (let's say because the previous tag is included and this
403 * FDT_END_NODE tag is not included) then we will only commit the result
404 * if we were able to add the region. That allows us to retry again next
407 * We keep track of a variable called 'want' which tells us what we want
408 * to include when there is no specific information provided by the
409 * h_include function for a particular property. This basically handles
410 * the inclusion of properties which are pulled in by virtue of the node
411 * they are in. So if you include a node, its properties are also
412 * included. In this case 'want' will be WANT_NODES_AND_PROPS. The
413 * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
414 * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
415 * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
416 * included, and properties will be skipped. If WANT_NOTHING is
417 * selected, then we will just rely on what the h_include() function
420 * Using 'want' we work out 'include', which tells us whether this
421 * current tag should be included or not. As you can imagine, if the
422 * value of 'include' changes, that means we are on a boundary between
423 * nodes to include and nodes to exclude. At this point we either close
424 * off a previous region and add it to the list, or mark the start of a
427 * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
428 * string list. Each of these dealt with as a whole (i.e. we create a
429 * region for each if it is to be included). For mem_rsvmap we don't
430 * allow it to merge with the first struct region. For the stringlist,
431 * we don't allow it to merge with the last struct region (which
432 * contains at minimum the FDT_END tag).
434 *********************************************************************/
436 int fdt_next_region(const void *fdt,
437 int (*h_include)(void *priv, const void *fdt, int offset,
438 int type, const char *data, int size),
439 void *priv, struct fdt_region *region,
440 char *path, int path_len, int flags,
441 struct fdt_region_state *info)
443 int base = fdt_off_dt_struct(fdt);
447 info->region = region;
449 if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
450 (flags & FDT_REG_ADD_MEM_RSVMAP)) {
451 /* Add the memory reserve map into its own region */
452 if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
453 fdt_off_dt_struct(fdt) -
454 fdt_off_mem_rsvmap(fdt)))
456 info->can_merge = 0; /* Don't allow merging with this */
457 info->ptrs.done = FDT_DONE_MEM_RSVMAP;
461 * Work through the tags one by one, deciding whether each needs to
462 * be included or not. We set the variable 'include' to indicate our
463 * decision. 'want' is used to track what we want to include - it
464 * allows us to pick up all the properties (and/or subnode tags) of
467 while (info->ptrs.done < FDT_DONE_STRUCT) {
468 const struct fdt_property *prop;
469 struct fdt_region_ptrs p;
479 * Make a copy of our pointers. If we make it to the end of
480 * this block then we will commit them back to info->ptrs.
481 * Otherwise we can try again from the same starting state
482 * next time we are called.
487 * Find the tag, and the offset of the next one. If we need to
488 * stop including tags, then by default we stop *after*
489 * including the current tag
491 offset = p.nextoffset;
492 tag = fdt_next_tag(fdt, offset, &p.nextoffset);
493 stop_at = p.nextoffset;
498 prop = fdt_get_property_by_offset(fdt, offset, NULL);
499 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
500 val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
503 include = p.want >= WANT_NODES_AND_PROPS;
507 * Make sure we include the } for this block.
508 * It might be more correct to have this done
509 * by the call to fdt_include_supernodes() in
510 * the case where it adds the node we are
511 * currently in, but this is equivalent.
513 if ((flags & FDT_REG_SUPERNODES) && val &&
515 p.want = WANT_NODES_ONLY;
518 /* Value grepping is not yet supported */
522 include = p.want >= WANT_NODES_AND_PROPS;
529 if (p.depth == FDT_MAX_DEPTH)
530 return -FDT_ERR_BADSTRUCTURE;
531 name = fdt_get_name(fdt, offset, &len);
532 if (p.end - path + 2 + len >= path_len)
533 return -FDT_ERR_NOSPACE;
535 /* Build the full path of this node */
536 if (p.end != path + 1)
540 info->stack[p.depth].want = p.want;
541 info->stack[p.depth].offset = offset;
544 * If we are not intending to include this node unless
545 * it matches, make sure we stop *before* its tag.
547 if (p.want == WANT_NODES_ONLY ||
548 !(flags & (FDT_REG_DIRECT_SUBNODES |
549 FDT_REG_ALL_SUBNODES))) {
551 p.want = WANT_NOTHING;
553 val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
556 /* Include this if requested */
558 p.want = (flags & FDT_REG_ALL_SUBNODES) ?
559 WANT_ALL_NODES_AND_PROPS :
560 WANT_NODES_AND_PROPS;
563 /* If not requested, decay our 'p.want' value */
565 if (p.want != WANT_ALL_NODES_AND_PROPS)
568 /* Not including this tag, so stop now */
574 * Decide whether to include this tag, and update our
575 * stack with the state for this node
578 info->stack[p.depth].included = include;
584 return -FDT_ERR_BADSTRUCTURE;
587 * If we don't want this node, stop right away, unless
588 * we are including subnodes
590 if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
592 p.want = info->stack[p.depth].want;
594 while (p.end > path && *--p.end != '/')
600 /* We always include the end tag */
602 p.done = FDT_DONE_STRUCT;
606 /* If this tag is to be included, mark it as region start */
607 if (include && info->start == -1) {
608 /* Include any supernodes required by this one */
609 if (flags & FDT_REG_SUPERNODES) {
610 if (fdt_include_supernodes(info, p.depth))
613 info->start = offset;
617 * If this tag is not to be included, finish up the current
620 if (!include && info->start != -1) {
621 if (fdt_add_region(info, base + info->start,
622 stop_at - info->start))
628 /* If we have made it this far, we can commit our pointers */
632 /* Add a region for the END tag and a separate one for string table */
633 if (info->ptrs.done < FDT_DONE_END) {
634 if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
635 return -FDT_ERR_BADSTRUCTURE;
637 if (fdt_add_region(info, base + info->start,
638 info->ptrs.nextoffset - info->start))
642 if (info->ptrs.done < FDT_DONE_STRINGS) {
643 if (flags & FDT_REG_ADD_STRING_TAB) {
645 if (fdt_off_dt_strings(fdt) <
646 base + info->ptrs.nextoffset)
647 return -FDT_ERR_BADLAYOUT;
648 if (fdt_add_region(info, fdt_off_dt_strings(fdt),
649 fdt_size_dt_strings(fdt)))
655 return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;