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 <libfdt_env.h>
17 #include "libfdt_internal.h"
20 * fdt_add_region() - Add a new region to our list
21 * @info: State information
22 * @offset: Start offset of region
23 * @size: Size of region
25 * The region is added if there is space, but in any case we increment the
26 * count. If permitted, and the new region overlaps the last one, we merge
29 static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
31 struct fdt_region *reg;
33 reg = info->region ? &info->region[info->count - 1] : NULL;
34 if (info->can_merge && info->count &&
35 info->count <= info->max_regions &&
36 reg && offset <= reg->offset + reg->size) {
37 reg->size = offset + size - reg->offset;
38 } else if (info->count++ < info->max_regions) {
51 static int region_list_contains_offset(struct fdt_region_state *info,
52 const void *fdt, int target)
54 struct fdt_region *reg;
57 target += fdt_off_dt_struct(fdt);
58 for (reg = info->region, num = 0; num < info->count; reg++, num++) {
59 if (target >= reg->offset && target < reg->offset + reg->size)
67 * fdt_add_alias_regions() - Add regions covering the aliases that we want
69 * The /aliases node is not automatically included by fdtgrep unless the
70 * command-line arguments cause to be included (or not excluded). However
71 * aliases are special in that we generally want to include those which
72 * reference a node that fdtgrep includes.
74 * In fact we want to include only aliases for those nodes still included in
75 * the fdt, and drop the other aliases since they point to nodes that will not
78 * This function scans the aliases and adds regions for those which we want
81 * @fdt: Device tree to scan
82 * @region: List of regions
83 * @count: Number of regions in the list so far (i.e. starting point for this
85 * @max_regions: Maximum number of regions in @region list
86 * @info: Place to put the region state
87 * @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
88 * not have enough room in the regions table for the regions we wanted to add.
90 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
91 int max_regions, struct fdt_region_state *info)
93 int base = fdt_off_dt_struct(fdt);
94 int node, node_end, offset;
97 node = fdt_subnode_offset(fdt, 0, "aliases");
99 return -FDT_ERR_NOTFOUND;
102 * Find the next node so that we know where the /aliases node ends. We
103 * need special handling if /aliases is the last node.
105 node_end = fdt_next_subnode(fdt, node);
106 if (node_end == -FDT_ERR_NOTFOUND)
107 /* Move back to the FDT_END_NODE tag of '/' */
108 node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
109 else if (node_end < 0) /* other error */
111 node_end -= sizeof(fdt32_t); /* Move to FDT_END_NODE tag of /aliases */
113 did_alias_header = 0;
114 info->region = region;
117 info->max_regions = max_regions;
119 for (offset = fdt_first_property_offset(fdt, node);
121 offset = fdt_next_property_offset(fdt, offset)) {
122 const struct fdt_property *prop;
126 prop = fdt_get_property_by_offset(fdt, offset, NULL);
127 name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
128 target = fdt_path_offset(fdt, name);
129 if (!region_list_contains_offset(info, fdt, target))
131 next = fdt_next_property_offset(fdt, offset);
135 if (!did_alias_header) {
136 fdt_add_region(info, base + node, 12);
137 did_alias_header = 1;
139 fdt_add_region(info, base + offset, next - offset);
142 /* Add the FDT_END_NODE tag */
143 if (did_alias_header)
144 fdt_add_region(info, base + node_end, sizeof(fdt32_t));
146 return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
150 * fdt_include_supernodes() - Include supernodes required by this node
151 * @info: State information
152 * @depth: Current stack depth
154 * When we decided to include a node or property which is not at the top
155 * level, this function forces the inclusion of higher level nodes. For
156 * example, given this tree:
163 * If we decide to include testing then we need the root node to have a valid
164 * tree. This function adds those regions.
166 static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
168 int base = fdt_off_dt_struct(info->fdt);
173 * Work down the stack looking for supernodes that we didn't include.
174 * The algortihm here is actually pretty simple, since we know that
175 * no previous subnode had to include these nodes, or if it did, we
176 * marked them as included (on the stack) already.
178 for (i = 0; i <= depth; i++) {
179 if (!info->stack[i].included) {
180 start = info->stack[i].offset;
182 /* Add the FDT_BEGIN_NODE tag of this supernode */
183 fdt_next_tag(info->fdt, start, &stop_at);
184 if (fdt_add_region(info, base + start, stop_at - start))
187 /* Remember that this supernode is now included */
188 info->stack[i].included = 1;
192 /* Force (later) generation of the FDT_END_NODE tag */
193 if (!info->stack[i].want)
194 info->stack[i].want = WANT_NODES_ONLY;
209 int fdt_first_region(const void *fdt,
210 int (*h_include)(void *priv, const void *fdt, int offset,
211 int type, const char *data, int size),
212 void *priv, struct fdt_region *region,
213 char *path, int path_len, int flags,
214 struct fdt_region_state *info)
216 struct fdt_region_ptrs *p = &info->ptrs;
218 /* Set up our state */
221 info->max_regions = 1;
223 p->want = WANT_NOTHING;
228 p->done = FDT_DONE_NOTHING;
230 return fdt_next_region(fdt, h_include, priv, region,
231 path, path_len, flags, info);
234 /***********************************************************************
236 * Theory of operation
238 * Note: in this description 'included' means that a node (or other part
239 * of the tree) should be included in the region list, i.e. it will have
240 * a region which covers its part of the tree.
242 * This function maintains some state from the last time it is called.
243 * It checks the next part of the tree that it is supposed to look at
244 * (p.nextoffset) to see if that should be included or not. When it
245 * finds something to include, it sets info->start to its offset. This
246 * marks the start of the region we want to include.
248 * Once info->start is set to the start (i.e. not -1), we continue
249 * scanning until we find something that we don't want included. This
250 * will be the end of a region. At this point we can close off the
251 * region and add it to the list. So we do so, and reset info->start
254 * One complication here is that we want to merge regions. So when we
255 * come to add another region later, we may in fact merge it with the
256 * previous one if one ends where the other starts.
258 * The function fdt_add_region() will return -1 if it fails to add the
259 * region, because we already have a region ready to be returned, and
260 * the new one cannot be merged in with it. In this case, we must return
261 * the region we found, and wait for another call to this function.
262 * When it comes, we will repeat the processing of the tag and again
263 * try to add a region. This time it will succeed.
265 * The current state of the pointers (stack, offset, etc.) is maintained
266 * in a ptrs member. At the start of every loop iteration we make a copy
267 * of it. The copy is then updated as the tag is processed. Only if we
268 * get to the end of the loop iteration (and successfully call
269 * fdt_add_region() if we need to) can we commit the changes we have
270 * made to these pointers. For example, if we see an FDT_END_NODE tag,
271 * we will decrement the depth value. But if we need to add a region
272 * for this tag (let's say because the previous tag is included and this
273 * FDT_END_NODE tag is not included) then we will only commit the result
274 * if we were able to add the region. That allows us to retry again next
277 * We keep track of a variable called 'want' which tells us what we want
278 * to include when there is no specific information provided by the
279 * h_include function for a particular property. This basically handles
280 * the inclusion of properties which are pulled in by virtue of the node
281 * they are in. So if you include a node, its properties are also
282 * included. In this case 'want' will be WANT_NODES_AND_PROPS. The
283 * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
284 * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
285 * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
286 * included, and properties will be skipped. If WANT_NOTHING is
287 * selected, then we will just rely on what the h_include() function
290 * Using 'want' we work out 'include', which tells us whether this
291 * current tag should be included or not. As you can imagine, if the
292 * value of 'include' changes, that means we are on a boundary between
293 * nodes to include and nodes to exclude. At this point we either close
294 * off a previous region and add it to the list, or mark the start of a
297 * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
298 * string list. Each of these dealt with as a whole (i.e. we create a
299 * region for each if it is to be included). For mem_rsvmap we don't
300 * allow it to merge with the first struct region. For the stringlist,
301 * we don't allow it to merge with the last struct region (which
302 * contains at minimum the FDT_END tag).
304 *********************************************************************/
306 int fdt_next_region(const void *fdt,
307 int (*h_include)(void *priv, const void *fdt, int offset,
308 int type, const char *data, int size),
309 void *priv, struct fdt_region *region,
310 char *path, int path_len, int flags,
311 struct fdt_region_state *info)
313 int base = fdt_off_dt_struct(fdt);
317 info->region = region;
319 if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
320 (flags & FDT_REG_ADD_MEM_RSVMAP)) {
321 /* Add the memory reserve map into its own region */
322 if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
323 fdt_off_dt_struct(fdt) -
324 fdt_off_mem_rsvmap(fdt)))
326 info->can_merge = 0; /* Don't allow merging with this */
327 info->ptrs.done = FDT_DONE_MEM_RSVMAP;
331 * Work through the tags one by one, deciding whether each needs to
332 * be included or not. We set the variable 'include' to indicate our
333 * decision. 'want' is used to track what we want to include - it
334 * allows us to pick up all the properties (and/or subnode tags) of
337 while (info->ptrs.done < FDT_DONE_STRUCT) {
338 const struct fdt_property *prop;
339 struct fdt_region_ptrs p;
349 * Make a copy of our pointers. If we make it to the end of
350 * this block then we will commit them back to info->ptrs.
351 * Otherwise we can try again from the same starting state
352 * next time we are called.
357 * Find the tag, and the offset of the next one. If we need to
358 * stop including tags, then by default we stop *after*
359 * including the current tag
361 offset = p.nextoffset;
362 tag = fdt_next_tag(fdt, offset, &p.nextoffset);
363 stop_at = p.nextoffset;
368 prop = fdt_get_property_by_offset(fdt, offset, NULL);
369 str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
370 val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
373 include = p.want >= WANT_NODES_AND_PROPS;
377 * Make sure we include the } for this block.
378 * It might be more correct to have this done
379 * by the call to fdt_include_supernodes() in
380 * the case where it adds the node we are
381 * currently in, but this is equivalent.
383 if ((flags & FDT_REG_SUPERNODES) && val &&
385 p.want = WANT_NODES_ONLY;
388 /* Value grepping is not yet supported */
392 include = p.want >= WANT_NODES_AND_PROPS;
399 if (p.depth == FDT_MAX_DEPTH)
400 return -FDT_ERR_TOODEEP;
401 name = fdt_get_name(fdt, offset, &len);
402 if (p.end - path + 2 + len >= path_len)
403 return -FDT_ERR_NOSPACE;
405 /* Build the full path of this node */
406 if (p.end != path + 1)
410 info->stack[p.depth].want = p.want;
411 info->stack[p.depth].offset = offset;
414 * If we are not intending to include this node unless
415 * it matches, make sure we stop *before* its tag.
417 if (p.want == WANT_NODES_ONLY ||
418 !(flags & (FDT_REG_DIRECT_SUBNODES |
419 FDT_REG_ALL_SUBNODES))) {
421 p.want = WANT_NOTHING;
423 val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
426 /* Include this if requested */
428 p.want = (flags & FDT_REG_ALL_SUBNODES) ?
429 WANT_ALL_NODES_AND_PROPS :
430 WANT_NODES_AND_PROPS;
433 /* If not requested, decay our 'p.want' value */
435 if (p.want != WANT_ALL_NODES_AND_PROPS)
438 /* Not including this tag, so stop now */
444 * Decide whether to include this tag, and update our
445 * stack with the state for this node
448 info->stack[p.depth].included = include;
454 return -FDT_ERR_BADSTRUCTURE;
457 * If we don't want this node, stop right away, unless
458 * we are including subnodes
460 if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
462 p.want = info->stack[p.depth].want;
464 while (p.end > path && *--p.end != '/')
470 /* We always include the end tag */
472 p.done = FDT_DONE_STRUCT;
476 /* If this tag is to be included, mark it as region start */
477 if (include && info->start == -1) {
478 /* Include any supernodes required by this one */
479 if (flags & FDT_REG_SUPERNODES) {
480 if (fdt_include_supernodes(info, p.depth))
483 info->start = offset;
487 * If this tag is not to be included, finish up the current
490 if (!include && info->start != -1) {
491 if (fdt_add_region(info, base + info->start,
492 stop_at - info->start))
498 /* If we have made it this far, we can commit our pointers */
502 /* Add a region for the END tag and a separate one for string table */
503 if (info->ptrs.done < FDT_DONE_END) {
504 if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
505 return -FDT_ERR_BADSTRUCTURE;
507 if (fdt_add_region(info, base + info->start,
508 info->ptrs.nextoffset - info->start))
512 if (info->ptrs.done < FDT_DONE_STRINGS) {
513 if (flags & FDT_REG_ADD_STRING_TAB) {
515 if (fdt_off_dt_strings(fdt) <
516 base + info->ptrs.nextoffset)
517 return -FDT_ERR_BADLAYOUT;
518 if (fdt_add_region(info, fdt_off_dt_strings(fdt),
519 fdt_size_dt_strings(fdt)))
525 return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;