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 #include "libfdt_internal.h"
19 #define FDT_MAX_DEPTH 32
21 static int str_in_list(const char *str, char * const list[], int count)
25 for (i = 0; i < count; i++)
26 if (!strcmp(list[i], str))
32 int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
33 char * const exc_prop[], int exc_prop_count,
34 struct fdt_region region[], int max_regions,
35 char *path, int path_len, int add_string_tab)
37 int stack[FDT_MAX_DEPTH] = { 0 };
45 int base = fdt_off_dt_struct(fdt);
50 const struct fdt_property *prop;
59 tag = fdt_next_tag(fdt, offset, &nextoffset);
66 prop = fdt_get_property_by_offset(fdt, offset, NULL);
67 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
68 if (str_in_list(str, exc_prop, exc_prop_count))
79 if (depth == FDT_MAX_DEPTH)
80 return -FDT_ERR_BADSTRUCTURE;
81 name = fdt_get_name(fdt, offset, &len);
82 if (end - path + 2 + len >= path_len)
83 return -FDT_ERR_NOSPACE;
91 if (str_in_list(path, inc, inc_count))
102 want = stack[depth--];
103 while (end > path && *--end != '/')
113 if (include && start == -1) {
114 /* Should we merge with previous? */
115 if (count && count <= max_regions &&
116 offset == region[count - 1].offset +
117 region[count - 1].size - base)
118 start = region[--count].offset - base;
123 if (!include && start != -1) {
124 if (count < max_regions) {
125 region[count].offset = base + start;
126 region[count].size = stop_at - start;
131 } while (tag != FDT_END);
133 if (nextoffset != fdt_size_dt_struct(fdt))
134 return -FDT_ERR_BADLAYOUT;
136 /* Add a region for the END tag and the string table */
137 if (count < max_regions) {
138 region[count].offset = base + start;
139 region[count].size = nextoffset - start;
141 region[count].size += fdt_size_dt_strings(fdt);
149 * fdt_add_region() - Add a new region to our list
150 * @info: State information
151 * @offset: Start offset of region
152 * @size: Size of region
154 * The region is added if there is space, but in any case we increment the
155 * count. If permitted, and the new region overlaps the last one, we merge
158 static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
160 struct fdt_region *reg;
162 reg = info->region ? &info->region[info->count - 1] : NULL;
163 if (info->can_merge && info->count &&
164 info->count <= info->max_regions &&
165 reg && offset <= reg->offset + reg->size) {
166 reg->size = offset + size - reg->offset;
167 } else if (info->count++ < info->max_regions) {
170 reg->offset = offset;
180 static int region_list_contains_offset(struct fdt_region_state *info,
181 const void *fdt, int target)
183 struct fdt_region *reg;
186 target += fdt_off_dt_struct(fdt);
187 for (reg = info->region, num = 0; num < info->count; reg++, num++) {
188 if (target >= reg->offset && target < reg->offset + reg->size)
196 * fdt_add_alias_regions() - Add regions covering the aliases that we want
198 * The /aliases node is not automatically included by fdtgrep unless the
199 * command-line arguments cause to be included (or not excluded). However
200 * aliases are special in that we generally want to include those which
201 * reference a node that fdtgrep includes.
203 * In fact we want to include only aliases for those nodes still included in
204 * the fdt, and drop the other aliases since they point to nodes that will not
207 * This function scans the aliases and adds regions for those which we want
210 * @fdt: Device tree to scan
211 * @region: List of regions
212 * @count: Number of regions in the list so far (i.e. starting point for this
214 * @max_regions: Maximum number of regions in @region list
215 * @info: Place to put the region state
216 * @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
217 * not have enough room in the regions table for the regions we wanted to add.
219 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
220 int max_regions, struct fdt_region_state *info)
222 int base = fdt_off_dt_struct(fdt);
223 int node, node_end, offset;
224 int did_alias_header;
226 node = fdt_subnode_offset(fdt, 0, "aliases");
228 return -FDT_ERR_NOTFOUND;
231 * Find the next node so that we know where the /aliases node ends. We
232 * need special handling if /aliases is the last node.
234 node_end = fdt_next_subnode(fdt, node);
235 if (node_end == -FDT_ERR_NOTFOUND)
236 /* Move back to the FDT_END_NODE tag of '/' */
237 node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
238 else if (node_end < 0) /* other error */
240 node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
242 did_alias_header = 0;
243 info->region = region;
246 info->max_regions = max_regions;
248 for (offset = fdt_first_property_offset(fdt, node);
250 offset = fdt_next_property_offset(fdt, offset)) {
251 const struct fdt_property *prop;
255 prop = fdt_get_property_by_offset(fdt, offset, NULL);
256 name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
257 target = fdt_path_offset(fdt, name);
258 if (!region_list_contains_offset(info, fdt, target))
260 next = fdt_next_property_offset(fdt, offset);
264 if (!did_alias_header) {
265 fdt_add_region(info, base + node, 12);
266 did_alias_header = 1;
268 fdt_add_region(info, base + offset, next - offset);
271 /* Add the FDT_END_NODE tag */
272 if (did_alias_header)
273 fdt_add_region(info, base + node_end, sizeof(fdt32_t));
275 return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
279 * fdt_include_supernodes() - Include supernodes required by this node
280 * @info: State information
281 * @depth: Current stack depth
283 * When we decided to include a node or property which is not at the top
284 * level, this function forces the inclusion of higher level nodes. For
285 * example, given this tree:
292 * If we decide to include testing then we need the root node to have a valid
293 * tree. This function adds those regions.
295 static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
297 int base = fdt_off_dt_struct(info->fdt);
302 * Work down the stack looking for supernodes that we didn't include.
303 * The algortihm here is actually pretty simple, since we know that
304 * no previous subnode had to include these nodes, or if it did, we
305 * marked them as included (on the stack) already.
307 for (i = 0; i <= depth; i++) {
308 if (!info->stack[i].included) {
309 start = info->stack[i].offset;
311 /* Add the FDT_BEGIN_NODE tag of this supernode */
312 fdt_next_tag(info->fdt, start, &stop_at);
313 if (fdt_add_region(info, base + start, stop_at - start))
316 /* Remember that this supernode is now included */
317 info->stack[i].included = 1;
321 /* Force (later) generation of the FDT_END_NODE tag */
322 if (!info->stack[i].want)
323 info->stack[i].want = WANT_NODES_ONLY;
338 int fdt_first_region(const void *fdt,
339 int (*h_include)(void *priv, const void *fdt, int offset,
340 int type, const char *data, int size),
341 void *priv, struct fdt_region *region,
342 char *path, int path_len, int flags,
343 struct fdt_region_state *info)
345 struct fdt_region_ptrs *p = &info->ptrs;
347 /* Set up our state */
350 info->max_regions = 1;
352 p->want = WANT_NOTHING;
357 p->done = FDT_DONE_NOTHING;
359 return fdt_next_region(fdt, h_include, priv, region,
360 path, path_len, flags, info);
363 /***********************************************************************
365 * Theory of operation
367 * Note: in this description 'included' means that a node (or other part
368 * of the tree) should be included in the region list, i.e. it will have
369 * a region which covers its part of the tree.
371 * This function maintains some state from the last time it is called.
372 * It checks the next part of the tree that it is supposed to look at
373 * (p.nextoffset) to see if that should be included or not. When it
374 * finds something to include, it sets info->start to its offset. This
375 * marks the start of the region we want to include.
377 * Once info->start is set to the start (i.e. not -1), we continue
378 * scanning until we find something that we don't want included. This
379 * will be the end of a region. At this point we can close off the
380 * region and add it to the list. So we do so, and reset info->start
383 * One complication here is that we want to merge regions. So when we
384 * come to add another region later, we may in fact merge it with the
385 * previous one if one ends where the other starts.
387 * The function fdt_add_region() will return -1 if it fails to add the
388 * region, because we already have a region ready to be returned, and
389 * the new one cannot be merged in with it. In this case, we must return
390 * the region we found, and wait for another call to this function.
391 * When it comes, we will repeat the processing of the tag and again
392 * try to add a region. This time it will succeed.
394 * The current state of the pointers (stack, offset, etc.) is maintained
395 * in a ptrs member. At the start of every loop iteration we make a copy
396 * of it. The copy is then updated as the tag is processed. Only if we
397 * get to the end of the loop iteration (and successfully call
398 * fdt_add_region() if we need to) can we commit the changes we have
399 * made to these pointers. For example, if we see an FDT_END_NODE tag,
400 * we will decrement the depth value. But if we need to add a region
401 * for this tag (let's say because the previous tag is included and this
402 * FDT_END_NODE tag is not included) then we will only commit the result
403 * if we were able to add the region. That allows us to retry again next
406 * We keep track of a variable called 'want' which tells us what we want
407 * to include when there is no specific information provided by the
408 * h_include function for a particular property. This basically handles
409 * the inclusion of properties which are pulled in by virtue of the node
410 * they are in. So if you include a node, its properties are also
411 * included. In this case 'want' will be WANT_NODES_AND_PROPS. The
412 * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
413 * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
414 * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
415 * included, and properties will be skipped. If WANT_NOTHING is
416 * selected, then we will just rely on what the h_include() function
419 * Using 'want' we work out 'include', which tells us whether this
420 * current tag should be included or not. As you can imagine, if the
421 * value of 'include' changes, that means we are on a boundary between
422 * nodes to include and nodes to exclude. At this point we either close
423 * off a previous region and add it to the list, or mark the start of a
426 * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
427 * string list. Each of these dealt with as a whole (i.e. we create a
428 * region for each if it is to be included). For mem_rsvmap we don't
429 * allow it to merge with the first struct region. For the stringlist,
430 * we don't allow it to merge with the last struct region (which
431 * contains at minimum the FDT_END tag).
433 *********************************************************************/
435 int fdt_next_region(const void *fdt,
436 int (*h_include)(void *priv, const void *fdt, int offset,
437 int type, const char *data, int size),
438 void *priv, struct fdt_region *region,
439 char *path, int path_len, int flags,
440 struct fdt_region_state *info)
442 int base = fdt_off_dt_struct(fdt);
446 info->region = region;
448 if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
449 (flags & FDT_REG_ADD_MEM_RSVMAP)) {
450 /* Add the memory reserve map into its own region */
451 if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
452 fdt_off_dt_struct(fdt) -
453 fdt_off_mem_rsvmap(fdt)))
455 info->can_merge = 0; /* Don't allow merging with this */
456 info->ptrs.done = FDT_DONE_MEM_RSVMAP;
460 * Work through the tags one by one, deciding whether each needs to
461 * be included or not. We set the variable 'include' to indicate our
462 * decision. 'want' is used to track what we want to include - it
463 * allows us to pick up all the properties (and/or subnode tags) of
466 while (info->ptrs.done < FDT_DONE_STRUCT) {
467 const struct fdt_property *prop;
468 struct fdt_region_ptrs p;
478 * Make a copy of our pointers. If we make it to the end of
479 * this block then we will commit them back to info->ptrs.
480 * Otherwise we can try again from the same starting state
481 * next time we are called.
486 * Find the tag, and the offset of the next one. If we need to
487 * stop including tags, then by default we stop *after*
488 * including the current tag
490 offset = p.nextoffset;
491 tag = fdt_next_tag(fdt, offset, &p.nextoffset);
492 stop_at = p.nextoffset;
497 prop = fdt_get_property_by_offset(fdt, offset, NULL);
498 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
499 val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
502 include = p.want >= WANT_NODES_AND_PROPS;
506 * Make sure we include the } for this block.
507 * It might be more correct to have this done
508 * by the call to fdt_include_supernodes() in
509 * the case where it adds the node we are
510 * currently in, but this is equivalent.
512 if ((flags & FDT_REG_SUPERNODES) && val &&
514 p.want = WANT_NODES_ONLY;
517 /* Value grepping is not yet supported */
521 include = p.want >= WANT_NODES_AND_PROPS;
528 if (p.depth == FDT_MAX_DEPTH)
529 return -FDT_ERR_BADSTRUCTURE;
530 name = fdt_get_name(fdt, offset, &len);
531 if (p.end - path + 2 + len >= path_len)
532 return -FDT_ERR_NOSPACE;
534 /* Build the full path of this node */
535 if (p.end != path + 1)
539 info->stack[p.depth].want = p.want;
540 info->stack[p.depth].offset = offset;
543 * If we are not intending to include this node unless
544 * it matches, make sure we stop *before* its tag.
546 if (p.want == WANT_NODES_ONLY ||
547 !(flags & (FDT_REG_DIRECT_SUBNODES |
548 FDT_REG_ALL_SUBNODES))) {
550 p.want = WANT_NOTHING;
552 val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
555 /* Include this if requested */
557 p.want = (flags & FDT_REG_ALL_SUBNODES) ?
558 WANT_ALL_NODES_AND_PROPS :
559 WANT_NODES_AND_PROPS;
562 /* If not requested, decay our 'p.want' value */
564 if (p.want != WANT_ALL_NODES_AND_PROPS)
567 /* Not including this tag, so stop now */
573 * Decide whether to include this tag, and update our
574 * stack with the state for this node
577 info->stack[p.depth].included = include;
583 return -FDT_ERR_BADSTRUCTURE;
586 * If we don't want this node, stop right away, unless
587 * we are including subnodes
589 if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
591 p.want = info->stack[p.depth].want;
593 while (p.end > path && *--p.end != '/')
599 /* We always include the end tag */
601 p.done = FDT_DONE_STRUCT;
605 /* If this tag is to be included, mark it as region start */
606 if (include && info->start == -1) {
607 /* Include any supernodes required by this one */
608 if (flags & FDT_REG_SUPERNODES) {
609 if (fdt_include_supernodes(info, p.depth))
612 info->start = offset;
616 * If this tag is not to be included, finish up the current
619 if (!include && info->start != -1) {
620 if (fdt_add_region(info, base + info->start,
621 stop_at - info->start))
627 /* If we have made it this far, we can commit our pointers */
631 /* Add a region for the END tag and a separate one for string table */
632 if (info->ptrs.done < FDT_DONE_END) {
633 if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
634 return -FDT_ERR_BADSTRUCTURE;
636 if (fdt_add_region(info, base + info->start,
637 info->ptrs.nextoffset - info->start))
641 if (info->ptrs.done < FDT_DONE_STRINGS) {
642 if (flags & FDT_REG_ADD_STRING_TAB) {
644 if (fdt_off_dt_strings(fdt) <
645 base + info->ptrs.nextoffset)
646 return -FDT_ERR_BADLAYOUT;
647 if (fdt_add_region(info, fdt_off_dt_strings(fdt),
648 fdt_size_dt_strings(fdt)))
654 return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;