1 /* $NetBSD: fdt_overlay.c,v 1.1.1.2 2019/12/22 12:30:38 skrll Exp $ */
2
3 // SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
4 /*
5 * libfdt - Flat Device Tree manipulation
6 * Copyright (C) 2016 Free Electrons
7 * Copyright (C) 2016 NextThing Co.
8 */
9 #include "libfdt_env.h"
10
11 #include <fdt.h>
12 #include <libfdt.h>
13
14 #include "libfdt_internal.h"
15
16 /**
17 * overlay_get_target_phandle - retrieves the target phandle of a fragment
18 * @fdto: pointer to the device tree overlay blob
19 * @fragment: node offset of the fragment in the overlay
20 *
21 * overlay_get_target_phandle() retrieves the target phandle of an
22 * overlay fragment when that fragment uses a phandle (target
23 * property) instead of a path (target-path property).
24 *
25 * returns:
26 * the phandle pointed by the target property
27 * 0, if the phandle was not found
28 * -1, if the phandle was malformed
29 */
overlay_get_target_phandle(const void * fdto,int fragment)30 static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
31 {
32 const fdt32_t *val;
33 int len;
34
35 val = fdt_getprop(fdto, fragment, "target", &len);
36 if (!val)
37 return 0;
38
39 if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1))
40 return (uint32_t)-1;
41
42 return fdt32_to_cpu(*val);
43 }
44
45 /**
46 * overlay_get_target - retrieves the offset of a fragment's target
47 * @fdt: Base device tree blob
48 * @fdto: Device tree overlay blob
49 * @fragment: node offset of the fragment in the overlay
50 * @pathp: pointer which receives the path of the target (or NULL)
51 *
52 * overlay_get_target() retrieves the target offset in the base
53 * device tree of a fragment, no matter how the actual targeting is
54 * done (through a phandle or a path)
55 *
56 * returns:
57 * the targeted node offset in the base device tree
58 * Negative error code on error
59 */
overlay_get_target(const void * fdt,const void * fdto,int fragment,char const ** pathp)60 static int overlay_get_target(const void *fdt, const void *fdto,
61 int fragment, char const **pathp)
62 {
63 uint32_t phandle;
64 const char *path = NULL;
65 int path_len = 0, ret;
66
67 /* Try first to do a phandle based lookup */
68 phandle = overlay_get_target_phandle(fdto, fragment);
69 if (phandle == (uint32_t)-1)
70 return -FDT_ERR_BADPHANDLE;
71
72 /* no phandle, try path */
73 if (!phandle) {
74 /* And then a path based lookup */
75 path = fdt_getprop(fdto, fragment, "target-path", &path_len);
76 if (path)
77 ret = fdt_path_offset(fdt, path);
78 else
79 ret = path_len;
80 } else
81 ret = fdt_node_offset_by_phandle(fdt, phandle);
82
83 /*
84 * If we haven't found either a target or a
85 * target-path property in a node that contains a
86 * __overlay__ subnode (we wouldn't be called
87 * otherwise), consider it a improperly written
88 * overlay
89 */
90 if (ret < 0 && path_len == -FDT_ERR_NOTFOUND)
91 ret = -FDT_ERR_BADOVERLAY;
92
93 /* return on error */
94 if (ret < 0)
95 return ret;
96
97 /* return pointer to path (if available) */
98 if (pathp)
99 *pathp = path ? path : NULL;
100
101 return ret;
102 }
103
104 /**
105 * overlay_phandle_add_offset - Increases a phandle by an offset
106 * @fdt: Base device tree blob
107 * @node: Device tree overlay blob
108 * @name: Name of the property to modify (phandle or linux,phandle)
109 * @delta: offset to apply
110 *
111 * overlay_phandle_add_offset() increments a node phandle by a given
112 * offset.
113 *
114 * returns:
115 * 0 on success.
116 * Negative error code on error
117 */
overlay_phandle_add_offset(void * fdt,int node,const char * name,uint32_t delta)118 static int overlay_phandle_add_offset(void *fdt, int node,
119 const char *name, uint32_t delta)
120 {
121 const fdt32_t *val;
122 uint32_t adj_val;
123 int len;
124
125 val = fdt_getprop(fdt, node, name, &len);
126 if (!val)
127 return len;
128
129 if (len != sizeof(*val))
130 return -FDT_ERR_BADPHANDLE;
131
132 adj_val = fdt32_to_cpu(*val);
133 if ((adj_val + delta) < adj_val)
134 return -FDT_ERR_NOPHANDLES;
135
136 adj_val += delta;
137 if (adj_val == (uint32_t)-1)
138 return -FDT_ERR_NOPHANDLES;
139
140 return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
141 }
142
143 /**
144 * overlay_adjust_node_phandles - Offsets the phandles of a node
145 * @fdto: Device tree overlay blob
146 * @node: Offset of the node we want to adjust
147 * @delta: Offset to shift the phandles of
148 *
149 * overlay_adjust_node_phandles() adds a constant to all the phandles
150 * of a given node. This is mainly use as part of the overlay
151 * application process, when we want to update all the overlay
152 * phandles to not conflict with the overlays of the base device tree.
153 *
154 * returns:
155 * 0 on success
156 * Negative error code on failure
157 */
overlay_adjust_node_phandles(void * fdto,int node,uint32_t delta)158 static int overlay_adjust_node_phandles(void *fdto, int node,
159 uint32_t delta)
160 {
161 int child;
162 int ret;
163
164 ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
165 if (ret && ret != -FDT_ERR_NOTFOUND)
166 return ret;
167
168 ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
169 if (ret && ret != -FDT_ERR_NOTFOUND)
170 return ret;
171
172 fdt_for_each_subnode(child, fdto, node) {
173 ret = overlay_adjust_node_phandles(fdto, child, delta);
174 if (ret)
175 return ret;
176 }
177
178 return 0;
179 }
180
181 /**
182 * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
183 * @fdto: Device tree overlay blob
184 * @delta: Offset to shift the phandles of
185 *
186 * overlay_adjust_local_phandles() adds a constant to all the
187 * phandles of an overlay. This is mainly use as part of the overlay
188 * application process, when we want to update all the overlay
189 * phandles to not conflict with the overlays of the base device tree.
190 *
191 * returns:
192 * 0 on success
193 * Negative error code on failure
194 */
overlay_adjust_local_phandles(void * fdto,uint32_t delta)195 static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
196 {
197 /*
198 * Start adjusting the phandles from the overlay root
199 */
200 return overlay_adjust_node_phandles(fdto, 0, delta);
201 }
202
203 /**
204 * overlay_update_local_node_references - Adjust the overlay references
205 * @fdto: Device tree overlay blob
206 * @tree_node: Node offset of the node to operate on
207 * @fixup_node: Node offset of the matching local fixups node
208 * @delta: Offset to shift the phandles of
209 *
210 * overlay_update_local_nodes_references() update the phandles
211 * pointing to a node within the device tree overlay by adding a
212 * constant delta.
213 *
214 * This is mainly used as part of a device tree application process,
215 * where you want the device tree overlays phandles to not conflict
216 * with the ones from the base device tree before merging them.
217 *
218 * returns:
219 * 0 on success
220 * Negative error code on failure
221 */
overlay_update_local_node_references(void * fdto,int tree_node,int fixup_node,uint32_t delta)222 static int overlay_update_local_node_references(void *fdto,
223 int tree_node,
224 int fixup_node,
225 uint32_t delta)
226 {
227 int fixup_prop;
228 int fixup_child;
229 int ret;
230
231 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
232 const fdt32_t *fixup_val;
233 const char *tree_val;
234 const char *name;
235 int fixup_len;
236 int tree_len;
237 int i;
238
239 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
240 &name, &fixup_len);
241 if (!fixup_val)
242 return fixup_len;
243
244 if (fixup_len % sizeof(uint32_t))
245 return -FDT_ERR_BADOVERLAY;
246
247 tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
248 if (!tree_val) {
249 if (tree_len == -FDT_ERR_NOTFOUND)
250 return -FDT_ERR_BADOVERLAY;
251
252 return tree_len;
253 }
254
255 for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
256 fdt32_t adj_val;
257 uint32_t poffset;
258
259 poffset = fdt32_to_cpu(fixup_val[i]);
260
261 /*
262 * phandles to fixup can be unaligned.
263 *
264 * Use a memcpy for the architectures that do
265 * not support unaligned accesses.
266 */
267 memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
268
269 adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta);
270
271 ret = fdt_setprop_inplace_namelen_partial(fdto,
272 tree_node,
273 name,
274 strlen(name),
275 poffset,
276 &adj_val,
277 sizeof(adj_val));
278 if (ret == -FDT_ERR_NOSPACE)
279 return -FDT_ERR_BADOVERLAY;
280
281 if (ret)
282 return ret;
283 }
284 }
285
286 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
287 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
288 NULL);
289 int tree_child;
290
291 tree_child = fdt_subnode_offset(fdto, tree_node,
292 fixup_child_name);
293 if (tree_child == -FDT_ERR_NOTFOUND)
294 return -FDT_ERR_BADOVERLAY;
295 if (tree_child < 0)
296 return tree_child;
297
298 ret = overlay_update_local_node_references(fdto,
299 tree_child,
300 fixup_child,
301 delta);
302 if (ret)
303 return ret;
304 }
305
306 return 0;
307 }
308
309 /**
310 * overlay_update_local_references - Adjust the overlay references
311 * @fdto: Device tree overlay blob
312 * @delta: Offset to shift the phandles of
313 *
314 * overlay_update_local_references() update all the phandles pointing
315 * to a node within the device tree overlay by adding a constant
316 * delta to not conflict with the base overlay.
317 *
318 * This is mainly used as part of a device tree application process,
319 * where you want the device tree overlays phandles to not conflict
320 * with the ones from the base device tree before merging them.
321 *
322 * returns:
323 * 0 on success
324 * Negative error code on failure
325 */
overlay_update_local_references(void * fdto,uint32_t delta)326 static int overlay_update_local_references(void *fdto, uint32_t delta)
327 {
328 int fixups;
329
330 fixups = fdt_path_offset(fdto, "/__local_fixups__");
331 if (fixups < 0) {
332 /* There's no local phandles to adjust, bail out */
333 if (fixups == -FDT_ERR_NOTFOUND)
334 return 0;
335
336 return fixups;
337 }
338
339 /*
340 * Update our local references from the root of the tree
341 */
342 return overlay_update_local_node_references(fdto, 0, fixups,
343 delta);
344 }
345
346 /**
347 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
348 * @fdt: Base Device Tree blob
349 * @fdto: Device tree overlay blob
350 * @symbols_off: Node offset of the symbols node in the base device tree
351 * @path: Path to a node holding a phandle in the overlay
352 * @path_len: number of path characters to consider
353 * @name: Name of the property holding the phandle reference in the overlay
354 * @name_len: number of name characters to consider
355 * @poffset: Offset within the overlay property where the phandle is stored
356 * @label: Label of the node referenced by the phandle
357 *
358 * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
359 * a node in the base device tree.
360 *
361 * This is part of the device tree overlay application process, when
362 * you want all the phandles in the overlay to point to the actual
363 * base dt nodes.
364 *
365 * returns:
366 * 0 on success
367 * Negative error code on failure
368 */
overlay_fixup_one_phandle(void * fdt,void * fdto,int symbols_off,const char * path,uint32_t path_len,const char * name,uint32_t name_len,int poffset,const char * label)369 static int overlay_fixup_one_phandle(void *fdt, void *fdto,
370 int symbols_off,
371 const char *path, uint32_t path_len,
372 const char *name, uint32_t name_len,
373 int poffset, const char *label)
374 {
375 const char *symbol_path;
376 uint32_t phandle;
377 fdt32_t phandle_prop;
378 int symbol_off, fixup_off;
379 int prop_len;
380
381 if (symbols_off < 0)
382 return symbols_off;
383
384 symbol_path = fdt_getprop(fdt, symbols_off, label,
385 &prop_len);
386 if (!symbol_path)
387 return prop_len;
388
389 symbol_off = fdt_path_offset(fdt, symbol_path);
390 if (symbol_off < 0)
391 return symbol_off;
392
393 phandle = fdt_get_phandle(fdt, symbol_off);
394 if (!phandle)
395 return -FDT_ERR_NOTFOUND;
396
397 fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
398 if (fixup_off == -FDT_ERR_NOTFOUND)
399 return -FDT_ERR_BADOVERLAY;
400 if (fixup_off < 0)
401 return fixup_off;
402
403 phandle_prop = cpu_to_fdt32(phandle);
404 return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
405 name, name_len, poffset,
406 &phandle_prop,
407 sizeof(phandle_prop));
408 };
409
410 /**
411 * overlay_fixup_phandle - Set an overlay phandle to the base one
412 * @fdt: Base Device Tree blob
413 * @fdto: Device tree overlay blob
414 * @symbols_off: Node offset of the symbols node in the base device tree
415 * @property: Property offset in the overlay holding the list of fixups
416 *
417 * overlay_fixup_phandle() resolves all the overlay phandles pointed
418 * to in a __fixups__ property, and updates them to match the phandles
419 * in use in the base device tree.
420 *
421 * This is part of the device tree overlay application process, when
422 * you want all the phandles in the overlay to point to the actual
423 * base dt nodes.
424 *
425 * returns:
426 * 0 on success
427 * Negative error code on failure
428 */
overlay_fixup_phandle(void * fdt,void * fdto,int symbols_off,int property)429 static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
430 int property)
431 {
432 const char *value;
433 const char *label;
434 int len;
435
436 value = fdt_getprop_by_offset(fdto, property,
437 &label, &len);
438 if (!value) {
439 if (len == -FDT_ERR_NOTFOUND)
440 return -FDT_ERR_INTERNAL;
441
442 return len;
443 }
444
445 do {
446 const char *path, *name, *fixup_end;
447 const char *fixup_str = value;
448 uint32_t path_len, name_len;
449 uint32_t fixup_len;
450 char *sep, *endptr;
451 int poffset, ret;
452
453 fixup_end = memchr(value, '\0', len);
454 if (!fixup_end)
455 return -FDT_ERR_BADOVERLAY;
456 fixup_len = fixup_end - fixup_str;
457
458 len -= fixup_len + 1;
459 value += fixup_len + 1;
460
461 path = fixup_str;
462 sep = memchr(fixup_str, ':', fixup_len);
463 if (!sep || *sep != ':')
464 return -FDT_ERR_BADOVERLAY;
465
466 path_len = sep - path;
467 if (path_len == (fixup_len - 1))
468 return -FDT_ERR_BADOVERLAY;
469
470 fixup_len -= path_len + 1;
471 name = sep + 1;
472 sep = memchr(name, ':', fixup_len);
473 if (!sep || *sep != ':')
474 return -FDT_ERR_BADOVERLAY;
475
476 name_len = sep - name;
477 if (!name_len)
478 return -FDT_ERR_BADOVERLAY;
479
480 poffset = strtoul(sep + 1, &endptr, 10);
481 if ((*endptr != '\0') || (endptr <= (sep + 1)))
482 return -FDT_ERR_BADOVERLAY;
483
484 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
485 path, path_len, name, name_len,
486 poffset, label);
487 if (ret)
488 return ret;
489 } while (len > 0);
490
491 return 0;
492 }
493
494 /**
495 * overlay_fixup_phandles - Resolve the overlay phandles to the base
496 * device tree
497 * @fdt: Base Device Tree blob
498 * @fdto: Device tree overlay blob
499 *
500 * overlay_fixup_phandles() resolves all the overlay phandles pointing
501 * to nodes in the base device tree.
502 *
503 * This is one of the steps of the device tree overlay application
504 * process, when you want all the phandles in the overlay to point to
505 * the actual base dt nodes.
506 *
507 * returns:
508 * 0 on success
509 * Negative error code on failure
510 */
overlay_fixup_phandles(void * fdt,void * fdto)511 static int overlay_fixup_phandles(void *fdt, void *fdto)
512 {
513 int fixups_off, symbols_off;
514 int property;
515
516 /* We can have overlays without any fixups */
517 fixups_off = fdt_path_offset(fdto, "/__fixups__");
518 if (fixups_off == -FDT_ERR_NOTFOUND)
519 return 0; /* nothing to do */
520 if (fixups_off < 0)
521 return fixups_off;
522
523 /* And base DTs without symbols */
524 symbols_off = fdt_path_offset(fdt, "/__symbols__");
525 if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
526 return symbols_off;
527
528 fdt_for_each_property_offset(property, fdto, fixups_off) {
529 int ret;
530
531 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
532 if (ret)
533 return ret;
534 }
535
536 return 0;
537 }
538
539 /**
540 * overlay_apply_node - Merges a node into the base device tree
541 * @fdt: Base Device Tree blob
542 * @target: Node offset in the base device tree to apply the fragment to
543 * @fdto: Device tree overlay blob
544 * @node: Node offset in the overlay holding the changes to merge
545 *
546 * overlay_apply_node() merges a node into a target base device tree
547 * node pointed.
548 *
549 * This is part of the final step in the device tree overlay
550 * application process, when all the phandles have been adjusted and
551 * resolved and you just have to merge overlay into the base device
552 * tree.
553 *
554 * returns:
555 * 0 on success
556 * Negative error code on failure
557 */
overlay_apply_node(void * fdt,int target,void * fdto,int node)558 static int overlay_apply_node(void *fdt, int target,
559 void *fdto, int node)
560 {
561 int property;
562 int subnode;
563
564 fdt_for_each_property_offset(property, fdto, node) {
565 const char *name;
566 const void *prop;
567 int prop_len;
568 int ret;
569
570 prop = fdt_getprop_by_offset(fdto, property, &name,
571 &prop_len);
572 if (prop_len == -FDT_ERR_NOTFOUND)
573 return -FDT_ERR_INTERNAL;
574 if (prop_len < 0)
575 return prop_len;
576
577 ret = fdt_setprop(fdt, target, name, prop, prop_len);
578 if (ret)
579 return ret;
580 }
581
582 fdt_for_each_subnode(subnode, fdto, node) {
583 const char *name = fdt_get_name(fdto, subnode, NULL);
584 int nnode;
585 int ret;
586
587 nnode = fdt_add_subnode(fdt, target, name);
588 if (nnode == -FDT_ERR_EXISTS) {
589 nnode = fdt_subnode_offset(fdt, target, name);
590 if (nnode == -FDT_ERR_NOTFOUND)
591 return -FDT_ERR_INTERNAL;
592 }
593
594 if (nnode < 0)
595 return nnode;
596
597 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
598 if (ret)
599 return ret;
600 }
601
602 return 0;
603 }
604
605 /**
606 * overlay_merge - Merge an overlay into its base device tree
607 * @fdt: Base Device Tree blob
608 * @fdto: Device tree overlay blob
609 *
610 * overlay_merge() merges an overlay into its base device tree.
611 *
612 * This is the next to last step in the device tree overlay application
613 * process, when all the phandles have been adjusted and resolved and
614 * you just have to merge overlay into the base device tree.
615 *
616 * returns:
617 * 0 on success
618 * Negative error code on failure
619 */
overlay_merge(void * fdt,void * fdto)620 static int overlay_merge(void *fdt, void *fdto)
621 {
622 int fragment;
623
624 fdt_for_each_subnode(fragment, fdto, 0) {
625 int overlay;
626 int target;
627 int ret;
628
629 /*
630 * Each fragments will have an __overlay__ node. If
631 * they don't, it's not supposed to be merged
632 */
633 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
634 if (overlay == -FDT_ERR_NOTFOUND)
635 continue;
636
637 if (overlay < 0)
638 return overlay;
639
640 target = overlay_get_target(fdt, fdto, fragment, NULL);
641 if (target < 0)
642 return target;
643
644 ret = overlay_apply_node(fdt, target, fdto, overlay);
645 if (ret)
646 return ret;
647 }
648
649 return 0;
650 }
651
get_path_len(const void * fdt,int nodeoffset)652 static int get_path_len(const void *fdt, int nodeoffset)
653 {
654 int len = 0, namelen;
655 const char *name;
656
657 FDT_RO_PROBE(fdt);
658
659 for (;;) {
660 name = fdt_get_name(fdt, nodeoffset, &namelen);
661 if (!name)
662 return namelen;
663
664 /* root? we're done */
665 if (namelen == 0)
666 break;
667
668 nodeoffset = fdt_parent_offset(fdt, nodeoffset);
669 if (nodeoffset < 0)
670 return nodeoffset;
671 len += namelen + 1;
672 }
673
674 /* in case of root pretend it's "/" */
675 if (len == 0)
676 len++;
677 return len;
678 }
679
680 /**
681 * overlay_symbol_update - Update the symbols of base tree after a merge
682 * @fdt: Base Device Tree blob
683 * @fdto: Device tree overlay blob
684 *
685 * overlay_symbol_update() updates the symbols of the base tree with the
686 * symbols of the applied overlay
687 *
688 * This is the last step in the device tree overlay application
689 * process, allowing the reference of overlay symbols by subsequent
690 * overlay operations.
691 *
692 * returns:
693 * 0 on success
694 * Negative error code on failure
695 */
overlay_symbol_update(void * fdt,void * fdto)696 static int overlay_symbol_update(void *fdt, void *fdto)
697 {
698 int root_sym, ov_sym, prop, path_len, fragment, target;
699 int len, frag_name_len, ret, rel_path_len;
700 const char *s, *e;
701 const char *path;
702 const char *name;
703 const char *frag_name;
704 const char *rel_path;
705 const char *target_path;
706 char *buf;
707 void *p;
708
709 ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");
710
711 /* if no overlay symbols exist no problem */
712 if (ov_sym < 0)
713 return 0;
714
715 root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");
716
717 /* it no root symbols exist we should create them */
718 if (root_sym == -FDT_ERR_NOTFOUND)
719 root_sym = fdt_add_subnode(fdt, 0, "__symbols__");
720
721 /* any error is fatal now */
722 if (root_sym < 0)
723 return root_sym;
724
725 /* iterate over each overlay symbol */
726 fdt_for_each_property_offset(prop, fdto, ov_sym) {
727 path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
728 if (!path)
729 return path_len;
730
731 /* verify it's a string property (terminated by a single \0) */
732 if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
733 return -FDT_ERR_BADVALUE;
734
735 /* keep end marker to avoid strlen() */
736 e = path + path_len;
737
738 if (*path != '/')
739 return -FDT_ERR_BADVALUE;
740
741 /* get fragment name first */
742 s = strchr(path + 1, '/');
743 if (!s) {
744 /* Symbol refers to something that won't end
745 * up in the target tree */
746 continue;
747 }
748
749 frag_name = path + 1;
750 frag_name_len = s - path - 1;
751
752 /* verify format; safe since "s" lies in \0 terminated prop */
753 len = sizeof("/__overlay__/") - 1;
754 if ((e - s) > len && (memcmp(s, "/__overlay__/", len) == 0)) {
755 /* /<fragment-name>/__overlay__/<relative-subnode-path> */
756 rel_path = s + len;
757 rel_path_len = e - rel_path;
758 } else if ((e - s) == len
759 && (memcmp(s, "/__overlay__", len - 1) == 0)) {
760 /* /<fragment-name>/__overlay__ */
761 rel_path = "";
762 rel_path_len = 0;
763 } else {
764 /* Symbol refers to something that won't end
765 * up in the target tree */
766 continue;
767 }
768
769 /* find the fragment index in which the symbol lies */
770 ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
771 frag_name_len);
772 /* not found? */
773 if (ret < 0)
774 return -FDT_ERR_BADOVERLAY;
775 fragment = ret;
776
777 /* an __overlay__ subnode must exist */
778 ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
779 if (ret < 0)
780 return -FDT_ERR_BADOVERLAY;
781
782 /* get the target of the fragment */
783 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
784 if (ret < 0)
785 return ret;
786 target = ret;
787
788 /* if we have a target path use */
789 if (!target_path) {
790 ret = get_path_len(fdt, target);
791 if (ret < 0)
792 return ret;
793 len = ret;
794 } else {
795 len = strlen(target_path);
796 }
797
798 ret = fdt_setprop_placeholder(fdt, root_sym, name,
799 len + (len > 1) + rel_path_len + 1, &p);
800 if (ret < 0)
801 return ret;
802
803 if (!target_path) {
804 /* again in case setprop_placeholder changed it */
805 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
806 if (ret < 0)
807 return ret;
808 target = ret;
809 }
810
811 buf = p;
812 if (len > 1) { /* target is not root */
813 if (!target_path) {
814 ret = fdt_get_path(fdt, target, buf, len + 1);
815 if (ret < 0)
816 return ret;
817 } else
818 memcpy(buf, target_path, len + 1);
819
820 } else
821 len--;
822
823 buf[len] = '/';
824 memcpy(buf + len + 1, rel_path, rel_path_len);
825 buf[len + 1 + rel_path_len] = '\0';
826 }
827
828 return 0;
829 }
830
fdt_overlay_apply(void * fdt,void * fdto)831 int fdt_overlay_apply(void *fdt, void *fdto)
832 {
833 uint32_t delta;
834 int ret;
835
836 FDT_RO_PROBE(fdt);
837 FDT_RO_PROBE(fdto);
838
839 ret = fdt_find_max_phandle(fdt, &delta);
840 if (ret)
841 goto err;
842
843 ret = overlay_adjust_local_phandles(fdto, delta);
844 if (ret)
845 goto err;
846
847 ret = overlay_update_local_references(fdto, delta);
848 if (ret)
849 goto err;
850
851 ret = overlay_fixup_phandles(fdt, fdto);
852 if (ret)
853 goto err;
854
855 ret = overlay_merge(fdt, fdto);
856 if (ret)
857 goto err;
858
859 ret = overlay_symbol_update(fdt, fdto);
860 if (ret)
861 goto err;
862
863 /*
864 * The overlay has been damaged, erase its magic.
865 */
866 fdt_set_magic(fdto, ~0);
867
868 return 0;
869
870 err:
871 /*
872 * The overlay might have been damaged, erase its magic.
873 */
874 fdt_set_magic(fdto, ~0);
875
876 /*
877 * The base device tree might have been damaged, erase its
878 * magic.
879 */
880 fdt_set_magic(fdt, ~0);
881
882 return ret;
883 }
884