2 * libfdt - Flat Device Tree manipulation
3 * Copyright (C) 2013 Google, Inc
4 * Written by Simon Glass <sjg@chromium.org>
5 * SPDX-License-Identifier: GPL-2.0+ BSD-2-Clause
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))
100 want = stack[depth--];
101 while (end > path && *--end != '/')
111 if (include && start == -1) {
112 /* Should we merge with previous? */
113 if (count && count <= max_regions &&
114 offset == region[count - 1].offset +
115 region[count - 1].size - base)
116 start = region[--count].offset - base;
121 if (!include && start != -1) {
122 if (count < max_regions) {
123 region[count].offset = base + start;
124 region[count].size = stop_at - start;
129 } while (tag != FDT_END);
131 if (nextoffset != fdt_size_dt_struct(fdt))
132 return -FDT_ERR_BADLAYOUT;
134 /* Add a region for the END tag and the string table */
135 if (count < max_regions) {
136 region[count].offset = base + start;
137 region[count].size = nextoffset - start;
139 region[count].size += fdt_size_dt_strings(fdt);
147 * fdt_add_region() - Add a new region to our list
148 * @info: State information
149 * @offset: Start offset of region
150 * @size: Size of region
152 * The region is added if there is space, but in any case we increment the
153 * count. If permitted, and the new region overlaps the last one, we merge
156 static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
158 struct fdt_region *reg;
160 reg = info->region ? &info->region[info->count - 1] : NULL;
161 if (info->can_merge && info->count &&
162 info->count <= info->max_regions &&
163 reg && offset <= reg->offset + reg->size) {
164 reg->size = offset + size - reg->offset;
165 } else if (info->count++ < info->max_regions) {
168 reg->offset = offset;
178 static int region_list_contains_offset(struct fdt_region_state *info,
179 const void *fdt, int target)
181 struct fdt_region *reg;
184 target += fdt_off_dt_struct(fdt);
185 for (reg = info->region, num = 0; num < info->count; reg++, num++) {
186 if (target >= reg->offset && target < reg->offset + reg->size)
194 * fdt_add_alias_regions() - Add regions covering the aliases that we want
196 * The /aliases node is not automatically included by fdtgrep unless the
197 * command-line arguments cause to be included (or not excluded). However
198 * aliases are special in that we generally want to include those which
199 * reference a node that fdtgrep includes.
201 * In fact we want to include only aliases for those nodes still included in
202 * the fdt, and drop the other aliases since they point to nodes that will not
205 * This function scans the aliases and adds regions for those which we want
208 * @fdt: Device tree to scan
209 * @region: List of regions
210 * @count: Number of regions in the list so far (i.e. starting point for this
212 * @max_regions: Maximum number of regions in @region list
213 * @info: Place to put the region state
214 * @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
215 * not have enough room in the regions table for the regions we wanted to add.
217 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
218 int max_regions, struct fdt_region_state *info)
220 int base = fdt_off_dt_struct(fdt);
221 int node, node_end, offset;
222 int did_alias_header;
224 node = fdt_subnode_offset(fdt, 0, "aliases");
226 return -FDT_ERR_NOTFOUND;
229 * Find the next node so that we know where the /aliases node ends. We
230 * need special handling if /aliases is the last node.
232 node_end = fdt_next_subnode(fdt, node);
233 if (node_end == -FDT_ERR_NOTFOUND)
234 /* Move back to the FDT_END_NODE tag of '/' */
235 node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
236 else if (node_end < 0) /* other error */
238 node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
240 did_alias_header = 0;
241 info->region = region;
244 info->max_regions = max_regions;
246 for (offset = fdt_first_property_offset(fdt, node);
248 offset = fdt_next_property_offset(fdt, offset)) {
249 const struct fdt_property *prop;
253 prop = fdt_get_property_by_offset(fdt, offset, NULL);
254 name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
255 target = fdt_path_offset(fdt, name);
256 if (!region_list_contains_offset(info, fdt, target))
258 next = fdt_next_property_offset(fdt, offset);
262 if (!did_alias_header) {
263 fdt_add_region(info, base + node, 12);
264 did_alias_header = 1;
266 fdt_add_region(info, base + offset, next - offset);
269 /* Add the FDT_END_NODE tag */
270 if (did_alias_header)
271 fdt_add_region(info, base + node_end, sizeof(fdt32_t));
273 return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
277 * fdt_include_supernodes() - Include supernodes required by this node
278 * @info: State information
279 * @depth: Current stack depth
281 * When we decided to include a node or property which is not at the top
282 * level, this function forces the inclusion of higher level nodes. For
283 * example, given this tree:
290 * If we decide to include testing then we need the root node to have a valid
291 * tree. This function adds those regions.
293 static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
295 int base = fdt_off_dt_struct(info->fdt);
300 * Work down the stack looking for supernodes that we didn't include.
301 * The algortihm here is actually pretty simple, since we know that
302 * no previous subnode had to include these nodes, or if it did, we
303 * marked them as included (on the stack) already.
305 for (i = 0; i <= depth; i++) {
306 if (!info->stack[i].included) {
307 start = info->stack[i].offset;
309 /* Add the FDT_BEGIN_NODE tag of this supernode */
310 fdt_next_tag(info->fdt, start, &stop_at);
311 if (fdt_add_region(info, base + start, stop_at - start))
314 /* Remember that this supernode is now included */
315 info->stack[i].included = 1;
319 /* Force (later) generation of the FDT_END_NODE tag */
320 if (!info->stack[i].want)
321 info->stack[i].want = WANT_NODES_ONLY;
336 int fdt_first_region(const void *fdt,
337 int (*h_include)(void *priv, const void *fdt, int offset,
338 int type, const char *data, int size),
339 void *priv, struct fdt_region *region,
340 char *path, int path_len, int flags,
341 struct fdt_region_state *info)
343 struct fdt_region_ptrs *p = &info->ptrs;
345 /* Set up our state */
348 info->max_regions = 1;
350 p->want = WANT_NOTHING;
355 p->done = FDT_DONE_NOTHING;
357 return fdt_next_region(fdt, h_include, priv, region,
358 path, path_len, flags, info);
361 /***********************************************************************
363 * Theory of operation
365 * Note: in this description 'included' means that a node (or other part
366 * of the tree) should be included in the region list, i.e. it will have
367 * a region which covers its part of the tree.
369 * This function maintains some state from the last time it is called.
370 * It checks the next part of the tree that it is supposed to look at
371 * (p.nextoffset) to see if that should be included or not. When it
372 * finds something to include, it sets info->start to its offset. This
373 * marks the start of the region we want to include.
375 * Once info->start is set to the start (i.e. not -1), we continue
376 * scanning until we find something that we don't want included. This
377 * will be the end of a region. At this point we can close off the
378 * region and add it to the list. So we do so, and reset info->start
381 * One complication here is that we want to merge regions. So when we
382 * come to add another region later, we may in fact merge it with the
383 * previous one if one ends where the other starts.
385 * The function fdt_add_region() will return -1 if it fails to add the
386 * region, because we already have a region ready to be returned, and
387 * the new one cannot be merged in with it. In this case, we must return
388 * the region we found, and wait for another call to this function.
389 * When it comes, we will repeat the processing of the tag and again
390 * try to add a region. This time it will succeed.
392 * The current state of the pointers (stack, offset, etc.) is maintained
393 * in a ptrs member. At the start of every loop iteration we make a copy
394 * of it. The copy is then updated as the tag is processed. Only if we
395 * get to the end of the loop iteration (and successfully call
396 * fdt_add_region() if we need to) can we commit the changes we have
397 * made to these pointers. For example, if we see an FDT_END_NODE tag,
398 * we will decrement the depth value. But if we need to add a region
399 * for this tag (let's say because the previous tag is included and this
400 * FDT_END_NODE tag is not included) then we will only commit the result
401 * if we were able to add the region. That allows us to retry again next
404 * We keep track of a variable called 'want' which tells us what we want
405 * to include when there is no specific information provided by the
406 * h_include function for a particular property. This basically handles
407 * the inclusion of properties which are pulled in by virtue of the node
408 * they are in. So if you include a node, its properties are also
409 * included. In this case 'want' will be WANT_NODES_AND_PROPS. The
410 * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
411 * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
412 * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
413 * included, and properties will be skipped. If WANT_NOTHING is
414 * selected, then we will just rely on what the h_include() function
417 * Using 'want' we work out 'include', which tells us whether this
418 * current tag should be included or not. As you can imagine, if the
419 * value of 'include' changes, that means we are on a boundary between
420 * nodes to include and nodes to exclude. At this point we either close
421 * off a previous region and add it to the list, or mark the start of a
424 * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
425 * string list. Each of these dealt with as a whole (i.e. we create a
426 * region for each if it is to be included). For mem_rsvmap we don't
427 * allow it to merge with the first struct region. For the stringlist,
428 * we don't allow it to merge with the last struct region (which
429 * contains at minimum the FDT_END tag).
431 *********************************************************************/
433 int fdt_next_region(const void *fdt,
434 int (*h_include)(void *priv, const void *fdt, int offset,
435 int type, const char *data, int size),
436 void *priv, struct fdt_region *region,
437 char *path, int path_len, int flags,
438 struct fdt_region_state *info)
440 int base = fdt_off_dt_struct(fdt);
444 info->region = region;
446 if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
447 (flags & FDT_REG_ADD_MEM_RSVMAP)) {
448 /* Add the memory reserve map into its own region */
449 if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
450 fdt_off_dt_struct(fdt) -
451 fdt_off_mem_rsvmap(fdt)))
453 info->can_merge = 0; /* Don't allow merging with this */
454 info->ptrs.done = FDT_DONE_MEM_RSVMAP;
458 * Work through the tags one by one, deciding whether each needs to
459 * be included or not. We set the variable 'include' to indicate our
460 * decision. 'want' is used to track what we want to include - it
461 * allows us to pick up all the properties (and/or subnode tags) of
464 while (info->ptrs.done < FDT_DONE_STRUCT) {
465 const struct fdt_property *prop;
466 struct fdt_region_ptrs p;
476 * Make a copy of our pointers. If we make it to the end of
477 * this block then we will commit them back to info->ptrs.
478 * Otherwise we can try again from the same starting state
479 * next time we are called.
484 * Find the tag, and the offset of the next one. If we need to
485 * stop including tags, then by default we stop *after*
486 * including the current tag
488 offset = p.nextoffset;
489 tag = fdt_next_tag(fdt, offset, &p.nextoffset);
490 stop_at = p.nextoffset;
495 prop = fdt_get_property_by_offset(fdt, offset, NULL);
496 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
497 val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
500 include = p.want >= WANT_NODES_AND_PROPS;
504 * Make sure we include the } for this block.
505 * It might be more correct to have this done
506 * by the call to fdt_include_supernodes() in
507 * the case where it adds the node we are
508 * currently in, but this is equivalent.
510 if ((flags & FDT_REG_SUPERNODES) && val &&
512 p.want = WANT_NODES_ONLY;
515 /* Value grepping is not yet supported */
519 include = p.want >= WANT_NODES_AND_PROPS;
526 if (p.depth == FDT_MAX_DEPTH)
527 return -FDT_ERR_BADSTRUCTURE;
528 name = fdt_get_name(fdt, offset, &len);
529 if (p.end - path + 2 + len >= path_len)
530 return -FDT_ERR_NOSPACE;
532 /* Build the full path of this node */
533 if (p.end != path + 1)
537 info->stack[p.depth].want = p.want;
538 info->stack[p.depth].offset = offset;
541 * If we are not intending to include this node unless
542 * it matches, make sure we stop *before* its tag.
544 if (p.want == WANT_NODES_ONLY ||
545 !(flags & (FDT_REG_DIRECT_SUBNODES |
546 FDT_REG_ALL_SUBNODES))) {
548 p.want = WANT_NOTHING;
550 val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
553 /* Include this if requested */
555 p.want = (flags & FDT_REG_ALL_SUBNODES) ?
556 WANT_ALL_NODES_AND_PROPS :
557 WANT_NODES_AND_PROPS;
560 /* If not requested, decay our 'p.want' value */
562 if (p.want != WANT_ALL_NODES_AND_PROPS)
565 /* Not including this tag, so stop now */
571 * Decide whether to include this tag, and update our
572 * stack with the state for this node
575 info->stack[p.depth].included = include;
581 return -FDT_ERR_BADSTRUCTURE;
584 * If we don't want this node, stop right away, unless
585 * we are including subnodes
587 if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
589 p.want = info->stack[p.depth].want;
591 while (p.end > path && *--p.end != '/')
597 /* We always include the end tag */
599 p.done = FDT_DONE_STRUCT;
603 /* If this tag is to be included, mark it as region start */
604 if (include && info->start == -1) {
605 /* Include any supernodes required by this one */
606 if (flags & FDT_REG_SUPERNODES) {
607 if (fdt_include_supernodes(info, p.depth))
610 info->start = offset;
614 * If this tag is not to be included, finish up the current
617 if (!include && info->start != -1) {
618 if (fdt_add_region(info, base + info->start,
619 stop_at - info->start))
625 /* If we have made it this far, we can commit our pointers */
629 /* Add a region for the END tag and a separate one for string table */
630 if (info->ptrs.done < FDT_DONE_END) {
631 if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
632 return -FDT_ERR_BADSTRUCTURE;
634 if (fdt_add_region(info, base + info->start,
635 info->ptrs.nextoffset - info->start))
639 if (info->ptrs.done < FDT_DONE_STRINGS) {
640 if (flags & FDT_REG_ADD_STRING_TAB) {
642 if (fdt_off_dt_strings(fdt) <
643 base + info->ptrs.nextoffset)
644 return -FDT_ERR_BADLAYOUT;
645 if (fdt_add_region(info, fdt_off_dt_strings(fdt),
646 fdt_size_dt_strings(fdt)))
652 return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;