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1// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
2/*
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2016 Free Electrons
5 * Copyright (C) 2016 NextThing Co.
6 */
7#include "libfdt_env.h"
8
9#include <fdt.h>
10#include <libfdt.h>
11
12#include "libfdt_internal.h"
13
14/**
15 * overlay_get_target_phandle - retrieves the target phandle of a fragment
16 * @fdto: pointer to the device tree overlay blob
17 * @fragment: node offset of the fragment in the overlay
18 *
19 * overlay_get_target_phandle() retrieves the target phandle of an
20 * overlay fragment when that fragment uses a phandle (target
21 * property) instead of a path (target-path property).
22 *
23 * returns:
24 * the phandle pointed by the target property
25 * 0, if the phandle was not found
26 * -1, if the phandle was malformed
27 */
28static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
29{
30 const fdt32_t *val;
31 int len;
32
33 val = fdt_getprop(fdto, fragment, "target", &len);
34 if (!val)
35 return 0;
36
37 if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1))
38 return (uint32_t)-1;
39
40 return fdt32_to_cpu(*val);
41}
42
43int fdt_overlay_target_offset(const void *fdt, const void *fdto,
44 int fragment_offset, char const **pathp)
45{
46 uint32_t phandle;
47 const char *path = NULL;
48 int path_len = 0, ret;
49
50 /* Try first to do a phandle based lookup */
51 phandle = overlay_get_target_phandle(fdto, fragment_offset);
52 if (phandle == (uint32_t)-1)
53 return -FDT_ERR_BADPHANDLE;
54
55 /* no phandle, try path */
56 if (!phandle) {
57 /* And then a path based lookup */
58 path = fdt_getprop(fdto, fragment_offset, "target-path", &path_len);
59 if (path)
60 ret = fdt_path_offset(fdt, path);
61 else
62 ret = path_len;
63 } else
64 ret = fdt_node_offset_by_phandle(fdt, phandle);
65
66 /*
67 * If we haven't found either a target or a
68 * target-path property in a node that contains a
69 * __overlay__ subnode (we wouldn't be called
70 * otherwise), consider it a improperly written
71 * overlay
72 */
73 if (ret < 0 && path_len == -FDT_ERR_NOTFOUND)
74 ret = -FDT_ERR_BADOVERLAY;
75
76 /* return on error */
77 if (ret < 0)
78 return ret;
79
80 /* return pointer to path (if available) */
81 if (pathp)
82 *pathp = path ? path : NULL;
83
84 return ret;
85}
86
87/**
88 * overlay_phandle_add_offset - Increases a phandle by an offset
89 * @fdt: Base device tree blob
90 * @node: Device tree overlay blob
91 * @name: Name of the property to modify (phandle or linux,phandle)
92 * @delta: offset to apply
93 *
94 * overlay_phandle_add_offset() increments a node phandle by a given
95 * offset.
96 *
97 * returns:
98 * 0 on success.
99 * Negative error code on error
100 */
101static int overlay_phandle_add_offset(void *fdt, int node,
102 const char *name, uint32_t delta)
103{
104 fdt32_t *valp, val;
105 int len;
106
107 valp = fdt_getprop_w(fdt, node, name, &len);
108 if (!valp)
109 return len;
110
111 if (len != sizeof(val))
112 return -FDT_ERR_BADPHANDLE;
113
114 val = fdt32_ld(valp);
115 if (val + delta < val || val + delta == (uint32_t)-1)
116 return -FDT_ERR_NOPHANDLES;
117
118 fdt32_st(valp, val + delta);
119 return 0;
120}
121
122/**
123 * overlay_adjust_node_phandles - Offsets the phandles of a node
124 * @fdto: Device tree overlay blob
125 * @node: Offset of the node we want to adjust
126 * @delta: Offset to shift the phandles of
127 *
128 * overlay_adjust_node_phandles() adds a constant to all the phandles
129 * of a given node. This is mainly use as part of the overlay
130 * application process, when we want to update all the overlay
131 * phandles to not conflict with the overlays of the base device tree.
132 *
133 * returns:
134 * 0 on success
135 * Negative error code on failure
136 */
137static int overlay_adjust_node_phandles(void *fdto, int node,
138 uint32_t delta)
139{
140 int child;
141 int ret;
142
143 ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
144 if (ret && ret != -FDT_ERR_NOTFOUND)
145 return ret;
146
147 ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
148 if (ret && ret != -FDT_ERR_NOTFOUND)
149 return ret;
150
151 fdt_for_each_subnode(child, fdto, node) {
152 ret = overlay_adjust_node_phandles(fdto, child, delta);
153 if (ret)
154 return ret;
155 }
156
157 return 0;
158}
159
160/**
161 * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
162 * @fdto: Device tree overlay blob
163 * @delta: Offset to shift the phandles of
164 *
165 * overlay_adjust_local_phandles() adds a constant to all the
166 * phandles of an overlay. This is mainly use as part of the overlay
167 * application process, when we want to update all the overlay
168 * phandles to not conflict with the overlays of the base device tree.
169 *
170 * returns:
171 * 0 on success
172 * Negative error code on failure
173 */
174static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
175{
176 /*
177 * Start adjusting the phandles from the overlay root
178 */
179 return overlay_adjust_node_phandles(fdto, 0, delta);
180}
181
182/**
183 * overlay_update_local_node_references - Adjust the overlay references
184 * @fdto: Device tree overlay blob
185 * @tree_node: Node offset of the node to operate on
186 * @fixup_node: Node offset of the matching local fixups node
187 * @delta: Offset to shift the phandles of
188 *
189 * overlay_update_local_nodes_references() update the phandles
190 * pointing to a node within the device tree overlay by adding a
191 * constant delta.
192 *
193 * This is mainly used as part of a device tree application process,
194 * where you want the device tree overlays phandles to not conflict
195 * with the ones from the base device tree before merging them.
196 *
197 * returns:
198 * 0 on success
199 * Negative error code on failure
200 */
201static int overlay_update_local_node_references(void *fdto,
202 int tree_node,
203 int fixup_node,
204 uint32_t delta)
205{
206 int fixup_prop;
207 int fixup_child;
208 int ret;
209
210 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
211 const fdt32_t *fixup_val;
212 const char *name;
213 char *tree_val;
214 int fixup_len;
215 int tree_len;
216 int i;
217
218 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
219 &name, &fixup_len);
220 if (!fixup_val)
221 return fixup_len;
222
223 if (fixup_len % sizeof(uint32_t))
224 return -FDT_ERR_BADOVERLAY;
225 fixup_len /= sizeof(uint32_t);
226
227 tree_val = fdt_getprop_w(fdto, tree_node, name, &tree_len);
228 if (!tree_val) {
229 if (tree_len == -FDT_ERR_NOTFOUND)
230 return -FDT_ERR_BADOVERLAY;
231
232 return tree_len;
233 }
234
235 for (i = 0; i < fixup_len; i++) {
236 fdt32_t *refp;
237
238 refp = (fdt32_t *)(tree_val + fdt32_ld_(fixup_val + i));
239
240 /*
241 * phandles to fixup can be unaligned, so use
242 * fdt32_{ld,st}() to read/write them.
243 */
244 fdt32_st(refp, fdt32_ld(refp) + delta);
245 }
246 }
247
248 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
249 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
250 NULL);
251 int tree_child;
252
253 tree_child = fdt_subnode_offset(fdto, tree_node,
254 fixup_child_name);
255 if (tree_child == -FDT_ERR_NOTFOUND)
256 return -FDT_ERR_BADOVERLAY;
257 if (tree_child < 0)
258 return tree_child;
259
260 ret = overlay_update_local_node_references(fdto,
261 tree_child,
262 fixup_child,
263 delta);
264 if (ret)
265 return ret;
266 }
267
268 return 0;
269}
270
271/**
272 * overlay_update_local_references - Adjust the overlay references
273 * @fdto: Device tree overlay blob
274 * @delta: Offset to shift the phandles of
275 *
276 * overlay_update_local_references() update all the phandles pointing
277 * to a node within the device tree overlay by adding a constant
278 * delta to not conflict with the base overlay.
279 *
280 * This is mainly used as part of a device tree application process,
281 * where you want the device tree overlays phandles to not conflict
282 * with the ones from the base device tree before merging them.
283 *
284 * returns:
285 * 0 on success
286 * Negative error code on failure
287 */
288static int overlay_update_local_references(void *fdto, uint32_t delta)
289{
290 int fixups;
291
292 fixups = fdt_path_offset(fdto, "/__local_fixups__");
293 if (fixups < 0) {
294 /* There's no local phandles to adjust, bail out */
295 if (fixups == -FDT_ERR_NOTFOUND)
296 return 0;
297
298 return fixups;
299 }
300
301 /*
302 * Update our local references from the root of the tree
303 */
304 return overlay_update_local_node_references(fdto, 0, fixups,
305 delta);
306}
307
308/**
309 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
310 * @fdt: Base Device Tree blob
311 * @fdto: Device tree overlay blob
312 * @symbols_off: Node offset of the symbols node in the base device tree
313 * @path: Path to a node holding a phandle in the overlay
314 * @path_len: number of path characters to consider
315 * @name: Name of the property holding the phandle reference in the overlay
316 * @name_len: number of name characters to consider
317 * @poffset: Offset within the overlay property where the phandle is stored
318 * @phandle: Phandle referencing the node
319 *
320 * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
321 * a node in the base device tree.
322 *
323 * This is part of the device tree overlay application process, when
324 * you want all the phandles in the overlay to point to the actual
325 * base dt nodes.
326 *
327 * returns:
328 * 0 on success
329 * Negative error code on failure
330 */
331static int overlay_fixup_one_phandle(void *fdt, void *fdto,
332 int symbols_off,
333 const char *path, uint32_t path_len,
334 const char *name, uint32_t name_len,
335 int poffset, uint32_t phandle)
336{
337 fdt32_t phandle_prop;
338 int fixup_off;
339
340 if (symbols_off < 0)
341 return symbols_off;
342
343 fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
344 if (fixup_off == -FDT_ERR_NOTFOUND)
345 return -FDT_ERR_BADOVERLAY;
346 if (fixup_off < 0)
347 return fixup_off;
348
349 phandle_prop = cpu_to_fdt32(phandle);
350 return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
351 name, name_len, poffset,
352 &phandle_prop,
353 sizeof(phandle_prop));
354};
355
356/**
357 * overlay_fixup_phandle - Set an overlay phandle to the base one
358 * @fdt: Base Device Tree blob
359 * @fdto: Device tree overlay blob
360 * @symbols_off: Node offset of the symbols node in the base device tree
361 * @property: Property offset in the overlay holding the list of fixups
362 *
363 * overlay_fixup_phandle() resolves all the overlay phandles pointed
364 * to in a __fixups__ property, and updates them to match the phandles
365 * in use in the base device tree.
366 *
367 * This is part of the device tree overlay application process, when
368 * you want all the phandles in the overlay to point to the actual
369 * base dt nodes.
370 *
371 * returns:
372 * 0 on success
373 * Negative error code on failure
374 */
375static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
376 int property)
377{
378 const char *value;
379 const char *label;
380 int len;
381 const char *symbol_path;
382 int prop_len;
383 int symbol_off;
384 uint32_t phandle;
385
386 value = fdt_getprop_by_offset(fdto, property,
387 &label, &len);
388 if (!value) {
389 if (len == -FDT_ERR_NOTFOUND)
390 return -FDT_ERR_INTERNAL;
391
392 return len;
393 }
394
395 symbol_path = fdt_getprop(fdt, symbols_off, label, &prop_len);
396 if (!symbol_path)
397 return prop_len;
398
399 symbol_off = fdt_path_offset(fdt, symbol_path);
400 if (symbol_off < 0)
401 return symbol_off;
402
403 phandle = fdt_get_phandle(fdt, symbol_off);
404 if (!phandle)
405 return -FDT_ERR_NOTFOUND;
406
407 do {
408 const char *path, *name, *fixup_end;
409 const char *fixup_str = value;
410 uint32_t path_len, name_len;
411 uint32_t fixup_len;
412 char *sep, *endptr;
413 int poffset, ret;
414
415 fixup_end = memchr(value, '\0', len);
416 if (!fixup_end)
417 return -FDT_ERR_BADOVERLAY;
418 fixup_len = fixup_end - fixup_str;
419
420 len -= fixup_len + 1;
421 value += fixup_len + 1;
422
423 path = fixup_str;
424 sep = memchr(fixup_str, ':', fixup_len);
425 if (!sep || *sep != ':')
426 return -FDT_ERR_BADOVERLAY;
427
428 path_len = sep - path;
429 if (path_len == (fixup_len - 1))
430 return -FDT_ERR_BADOVERLAY;
431
432 fixup_len -= path_len + 1;
433 name = sep + 1;
434 sep = memchr(name, ':', fixup_len);
435 if (!sep || *sep != ':')
436 return -FDT_ERR_BADOVERLAY;
437
438 name_len = sep - name;
439 if (!name_len)
440 return -FDT_ERR_BADOVERLAY;
441
442 poffset = strtoul(sep + 1, &endptr, 10);
443 if ((*endptr != '\0') || (endptr <= (sep + 1)))
444 return -FDT_ERR_BADOVERLAY;
445
446 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
447 path, path_len, name, name_len,
448 poffset, phandle);
449 if (ret)
450 return ret;
451 } while (len > 0);
452
453 return 0;
454}
455
456/**
457 * overlay_fixup_phandles - Resolve the overlay phandles to the base
458 * device tree
459 * @fdt: Base Device Tree blob
460 * @fdto: Device tree overlay blob
461 *
462 * overlay_fixup_phandles() resolves all the overlay phandles pointing
463 * to nodes in the base device tree.
464 *
465 * This is one of the steps of the device tree overlay application
466 * process, when you want all the phandles in the overlay to point to
467 * the actual base dt nodes.
468 *
469 * returns:
470 * 0 on success
471 * Negative error code on failure
472 */
473static int overlay_fixup_phandles(void *fdt, void *fdto)
474{
475 int fixups_off, symbols_off;
476 int property;
477
478 /* We can have overlays without any fixups */
479 fixups_off = fdt_path_offset(fdto, "/__fixups__");
480 if (fixups_off == -FDT_ERR_NOTFOUND)
481 return 0; /* nothing to do */
482 if (fixups_off < 0)
483 return fixups_off;
484
485 /* And base DTs without symbols */
486 symbols_off = fdt_path_offset(fdt, "/__symbols__");
487 if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
488 return symbols_off;
489
490 fdt_for_each_property_offset(property, fdto, fixups_off) {
491 int ret;
492
493 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
494 if (ret)
495 return ret;
496 }
497
498 return 0;
499}
500
501/**
502 * overlay_adjust_local_conflicting_phandle: Changes a phandle value
503 * @fdto: Device tree overlay
504 * @node: The node the phandle is set for
505 * @fdt_phandle: The new value for the phandle
506 *
507 * returns:
508 * 0 on success
509 * Negative error code on failure
510 */
511static int overlay_adjust_local_conflicting_phandle(void *fdto, int node,
512 uint32_t fdt_phandle)
513{
514 const fdt32_t *php;
515 int len, ret;
516
517 php = fdt_getprop(fdto, node, "phandle", &len);
518 if (php && len == sizeof(*php)) {
519 ret = fdt_setprop_inplace_u32(fdto, node, "phandle", fdt_phandle);
520 if (ret)
521 return ret;
522 }
523
524 php = fdt_getprop(fdto, node, "linux,phandle", &len);
525 if (php && len == sizeof(*php)) {
526 ret = fdt_setprop_inplace_u32(fdto, node, "linux,phandle", fdt_phandle);
527 if (ret)
528 return ret;
529 }
530
531 return 0;
532}
533
534/**
535 * overlay_update_node_conflicting_references - Recursively replace phandle values
536 * @fdto: Device tree overlay blob
537 * @tree_node: Node to recurse into
538 * @fixup_node: Node offset of the matching local fixups node
539 * @fdt_phandle: Value to replace phandles with
540 * @fdto_phandle: Value to be replaced
541 *
542 * Replaces all phandles with value @fdto_phandle by @fdt_phandle.
543 *
544 * returns:
545 * 0 on success
546 * Negative error code on failure
547 */
548static int overlay_update_node_conflicting_references(void *fdto, int tree_node,
549 int fixup_node,
550 uint32_t fdt_phandle,
551 uint32_t fdto_phandle)
552{
553 int fixup_prop;
554 int fixup_child;
555 int ret;
556
557 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
558 const fdt32_t *fixup_val;
559 const char *name;
560 char *tree_val;
561 int fixup_len;
562 int tree_len;
563 int i;
564
565 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
566 &name, &fixup_len);
567 if (!fixup_val)
568 return fixup_len;
569
570 if (fixup_len % sizeof(uint32_t))
571 return -FDT_ERR_BADOVERLAY;
572 fixup_len /= sizeof(uint32_t);
573
574 tree_val = fdt_getprop_w(fdto, tree_node, name, &tree_len);
575 if (!tree_val) {
576 if (tree_len == -FDT_ERR_NOTFOUND)
577 return -FDT_ERR_BADOVERLAY;
578
579 return tree_len;
580 }
581
582 for (i = 0; i < fixup_len; i++) {
583 fdt32_t *refp;
584 uint32_t valp;
585
586 refp = (fdt32_t *)(tree_val + fdt32_ld_(fixup_val + i));
587 valp = fdt32_ld(refp);
588
589 if (valp == fdto_phandle)
590 fdt32_st(refp, fdt_phandle);
591 }
592 }
593
594 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
595 const char *fixup_child_name = fdt_get_name(fdto, fixup_child, NULL);
596 int tree_child;
597
598 tree_child = fdt_subnode_offset(fdto, tree_node, fixup_child_name);
599
600 if (tree_child == -FDT_ERR_NOTFOUND)
601 return -FDT_ERR_BADOVERLAY;
602 if (tree_child < 0)
603 return tree_child;
604
605 ret = overlay_update_node_conflicting_references(fdto, tree_child,
606 fixup_child,
607 fdt_phandle,
608 fdto_phandle);
609 if (ret)
610 return ret;
611 }
612
613 return 0;
614}
615
616/**
617 * overlay_update_local_conflicting_references - Recursively replace phandle values
618 * @fdto: Device tree overlay blob
619 * @fdt_phandle: Value to replace phandles with
620 * @fdto_phandle: Value to be replaced
621 *
622 * Replaces all phandles with value @fdto_phandle by @fdt_phandle.
623 *
624 * returns:
625 * 0 on success
626 * Negative error code on failure
627 */
628static int overlay_update_local_conflicting_references(void *fdto,
629 uint32_t fdt_phandle,
630 uint32_t fdto_phandle)
631{
632 int fixups;
633
634 fixups = fdt_path_offset(fdto, "/__local_fixups__");
635 if (fixups == -FDT_ERR_NOTFOUND)
636 return 0;
637 if (fixups < 0)
638 return fixups;
639
640 return overlay_update_node_conflicting_references(fdto, 0, fixups,
641 fdt_phandle,
642 fdto_phandle);
643}
644
645/**
646 * overlay_prevent_phandle_overwrite_node - Helper function for overlay_prevent_phandle_overwrite
647 * @fdt: Base Device tree blob
648 * @fdtnode: Node in fdt that is checked for an overwrite
649 * @fdto: Device tree overlay blob
650 * @fdtonode: Node in fdto matching @fdtnode
651 *
652 * returns:
653 * 0 on success
654 * Negative error code on failure
655 */
656static int overlay_prevent_phandle_overwrite_node(void *fdt, int fdtnode,
657 void *fdto, int fdtonode)
658{
659 uint32_t fdt_phandle, fdto_phandle;
660 int fdtochild;
661
662 fdt_phandle = fdt_get_phandle(fdt, fdtnode);
663 fdto_phandle = fdt_get_phandle(fdto, fdtonode);
664
665 if (fdt_phandle && fdto_phandle) {
666 int ret;
667
668 ret = overlay_adjust_local_conflicting_phandle(fdto, fdtonode,
669 fdt_phandle);
670 if (ret)
671 return ret;
672
673 ret = overlay_update_local_conflicting_references(fdto,
674 fdt_phandle,
675 fdto_phandle);
676 if (ret)
677 return ret;
678 }
679
680 fdt_for_each_subnode(fdtochild, fdto, fdtonode) {
681 const char *name = fdt_get_name(fdto, fdtochild, NULL);
682 int fdtchild;
683 int ret;
684
685 fdtchild = fdt_subnode_offset(fdt, fdtnode, name);
686 if (fdtchild == -FDT_ERR_NOTFOUND)
687 /*
688 * no further overwrites possible here as this node is
689 * new
690 */
691 continue;
692
693 ret = overlay_prevent_phandle_overwrite_node(fdt, fdtchild,
694 fdto, fdtochild);
695 if (ret)
696 return ret;
697 }
698
699 return 0;
700}
701
702/**
703 * overlay_prevent_phandle_overwrite - Fixes overlay phandles to not overwrite base phandles
704 * @fdt: Base Device Tree blob
705 * @fdto: Device tree overlay blob
706 *
707 * Checks recursively if applying fdto overwrites phandle values in the base
708 * dtb. When such a phandle is found, the fdto is changed to use the fdt's
709 * phandle value to not break references in the base.
710 *
711 * returns:
712 * 0 on success
713 * Negative error code on failure
714 */
715static int overlay_prevent_phandle_overwrite(void *fdt, void *fdto)
716{
717 int fragment;
718
719 fdt_for_each_subnode(fragment, fdto, 0) {
720 int overlay;
721 int target;
722 int ret;
723
724 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
725 if (overlay == -FDT_ERR_NOTFOUND)
726 continue;
727
728 if (overlay < 0)
729 return overlay;
730
731 target = fdt_overlay_target_offset(fdt, fdto, fragment, NULL);
732 if (target == -FDT_ERR_NOTFOUND)
733 /*
734 * The subtree doesn't exist in the base, so nothing
735 * will be overwritten.
736 */
737 continue;
738 else if (target < 0)
739 return target;
740
741 ret = overlay_prevent_phandle_overwrite_node(fdt, target,
742 fdto, overlay);
743 if (ret)
744 return ret;
745 }
746
747 return 0;
748}
749
750/**
751 * overlay_apply_node - Merges a node into the base device tree
752 * @fdt: Base Device Tree blob
753 * @target: Node offset in the base device tree to apply the fragment to
754 * @fdto: Device tree overlay blob
755 * @node: Node offset in the overlay holding the changes to merge
756 *
757 * overlay_apply_node() merges a node into a target base device tree
758 * node pointed.
759 *
760 * This is part of the final step in the device tree overlay
761 * application process, when all the phandles have been adjusted and
762 * resolved and you just have to merge overlay into the base device
763 * tree.
764 *
765 * returns:
766 * 0 on success
767 * Negative error code on failure
768 */
769static int overlay_apply_node(void *fdt, int target,
770 void *fdto, int node)
771{
772 int property;
773 int subnode;
774
775 fdt_for_each_property_offset(property, fdto, node) {
776 const char *name;
777 const void *prop;
778 int prop_len;
779 int ret;
780
781 prop = fdt_getprop_by_offset(fdto, property, &name,
782 &prop_len);
783 if (prop_len == -FDT_ERR_NOTFOUND)
784 return -FDT_ERR_INTERNAL;
785 if (prop_len < 0)
786 return prop_len;
787
788 ret = fdt_setprop(fdt, target, name, prop, prop_len);
789 if (ret)
790 return ret;
791 }
792
793 fdt_for_each_subnode(subnode, fdto, node) {
794 const char *name = fdt_get_name(fdto, subnode, NULL);
795 int nnode;
796 int ret;
797
798 nnode = fdt_add_subnode(fdt, target, name);
799 if (nnode == -FDT_ERR_EXISTS) {
800 nnode = fdt_subnode_offset(fdt, target, name);
801 if (nnode == -FDT_ERR_NOTFOUND)
802 return -FDT_ERR_INTERNAL;
803 }
804
805 if (nnode < 0)
806 return nnode;
807
808 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
809 if (ret)
810 return ret;
811 }
812
813 return 0;
814}
815
816/**
817 * overlay_merge - Merge an overlay into its base device tree
818 * @fdt: Base Device Tree blob
819 * @fdto: Device tree overlay blob
820 *
821 * overlay_merge() merges an overlay into its base device tree.
822 *
823 * This is the next to last step in the device tree overlay application
824 * process, when all the phandles have been adjusted and resolved and
825 * you just have to merge overlay into the base device tree.
826 *
827 * returns:
828 * 0 on success
829 * Negative error code on failure
830 */
831static int overlay_merge(void *fdt, void *fdto)
832{
833 int fragment;
834
835 fdt_for_each_subnode(fragment, fdto, 0) {
836 int overlay;
837 int target;
838 int ret;
839
840 /*
841 * Each fragments will have an __overlay__ node. If
842 * they don't, it's not supposed to be merged
843 */
844 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
845 if (overlay == -FDT_ERR_NOTFOUND)
846 continue;
847
848 if (overlay < 0)
849 return overlay;
850
851 target = fdt_overlay_target_offset(fdt, fdto, fragment, NULL);
852 if (target < 0)
853 return target;
854
855 ret = overlay_apply_node(fdt, target, fdto, overlay);
856 if (ret)
857 return ret;
858 }
859
860 return 0;
861}
862
863static int get_path_len(const void *fdt, int nodeoffset)
864{
865 int len = 0, namelen;
866 const char *name;
867
868 FDT_RO_PROBE(fdt);
869
870 for (;;) {
871 name = fdt_get_name(fdt, nodeoffset, &namelen);
872 if (!name)
873 return namelen;
874
875 /* root? we're done */
876 if (namelen == 0)
877 break;
878
879 nodeoffset = fdt_parent_offset(fdt, nodeoffset);
880 if (nodeoffset < 0)
881 return nodeoffset;
882 len += namelen + 1;
883 }
884
885 /* in case of root pretend it's "/" */
886 if (len == 0)
887 len++;
888 return len;
889}
890
891/**
892 * overlay_symbol_update - Update the symbols of base tree after a merge
893 * @fdt: Base Device Tree blob
894 * @fdto: Device tree overlay blob
895 *
896 * overlay_symbol_update() updates the symbols of the base tree with the
897 * symbols of the applied overlay
898 *
899 * This is the last step in the device tree overlay application
900 * process, allowing the reference of overlay symbols by subsequent
901 * overlay operations.
902 *
903 * returns:
904 * 0 on success
905 * Negative error code on failure
906 */
907static int overlay_symbol_update(void *fdt, void *fdto)
908{
909 int root_sym, ov_sym, prop, path_len, fragment, target;
910 int len, frag_name_len, ret, rel_path_len;
911 const char *s, *e;
912 const char *path;
913 const char *name;
914 const char *frag_name;
915 const char *rel_path;
916 const char *target_path;
917 char *buf;
918 void *p;
919
920 ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");
921
922 /* if no overlay symbols exist no problem */
923 if (ov_sym < 0)
924 return 0;
925
926 root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");
927
928 /* it no root symbols exist we should create them */
929 if (root_sym == -FDT_ERR_NOTFOUND)
930 root_sym = fdt_add_subnode(fdt, 0, "__symbols__");
931
932 /* any error is fatal now */
933 if (root_sym < 0)
934 return root_sym;
935
936 /* iterate over each overlay symbol */
937 fdt_for_each_property_offset(prop, fdto, ov_sym) {
938 path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
939 if (!path)
940 return path_len;
941
942 /* verify it's a string property (terminated by a single \0) */
943 if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
944 return -FDT_ERR_BADVALUE;
945
946 /* keep end marker to avoid strlen() */
947 e = path + path_len;
948
949 if (*path != '/')
950 return -FDT_ERR_BADVALUE;
951
952 /* get fragment name first */
953 s = strchr(path + 1, '/');
954 if (!s) {
955 /* Symbol refers to something that won't end
956 * up in the target tree */
957 continue;
958 }
959
960 frag_name = path + 1;
961 frag_name_len = s - path - 1;
962
963 /* verify format; safe since "s" lies in \0 terminated prop */
964 len = sizeof("/__overlay__/") - 1;
965 if ((e - s) > len && (memcmp(s, "/__overlay__/", len) == 0)) {
966 /* /<fragment-name>/__overlay__/<relative-subnode-path> */
967 rel_path = s + len;
968 rel_path_len = e - rel_path - 1;
969 } else if ((e - s) == len
970 && (memcmp(s, "/__overlay__", len - 1) == 0)) {
971 /* /<fragment-name>/__overlay__ */
972 rel_path = "";
973 rel_path_len = 0;
974 } else {
975 /* Symbol refers to something that won't end
976 * up in the target tree */
977 continue;
978 }
979
980 /* find the fragment index in which the symbol lies */
981 ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
982 frag_name_len);
983 /* not found? */
984 if (ret < 0)
985 return -FDT_ERR_BADOVERLAY;
986 fragment = ret;
987
988 /* an __overlay__ subnode must exist */
989 ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
990 if (ret < 0)
991 return -FDT_ERR_BADOVERLAY;
992
993 /* get the target of the fragment */
994 ret = fdt_overlay_target_offset(fdt, fdto, fragment, &target_path);
995 if (ret < 0)
996 return ret;
997 target = ret;
998
999 /* if we have a target path use */
1000 if (!target_path) {
1001 ret = get_path_len(fdt, target);
1002 if (ret < 0)
1003 return ret;
1004 len = ret;
1005 } else {
1006 len = strlen(target_path);
1007 }
1008
1009 ret = fdt_setprop_placeholder(fdt, root_sym, name,
1010 len + (len > 1) + rel_path_len + 1, &p);
1011 if (ret < 0)
1012 return ret;
1013
1014 if (!target_path) {
1015 /* again in case setprop_placeholder changed it */
1016 ret = fdt_overlay_target_offset(fdt, fdto, fragment, &target_path);
1017 if (ret < 0)
1018 return ret;
1019 target = ret;
1020 }
1021
1022 buf = p;
1023 if (len > 1) { /* target is not root */
1024 if (!target_path) {
1025 ret = fdt_get_path(fdt, target, buf, len + 1);
1026 if (ret < 0)
1027 return ret;
1028 } else
1029 memcpy(buf, target_path, len + 1);
1030
1031 } else
1032 len--;
1033
1034 buf[len] = '/';
1035 memcpy(buf + len + 1, rel_path, rel_path_len);
1036 buf[len + 1 + rel_path_len] = '\0';
1037 }
1038
1039 return 0;
1040}
1041
1042int fdt_overlay_apply(void *fdt, void *fdto)
1043{
1044 uint32_t delta;
1045 int ret;
1046
1047 FDT_RO_PROBE(fdt);
1048 FDT_RO_PROBE(fdto);
1049
1050 ret = fdt_find_max_phandle(fdt, &delta);
1051 if (ret)
1052 goto err;
1053
1054 /* Increase all phandles in the fdto by delta */
1055 ret = overlay_adjust_local_phandles(fdto, delta);
1056 if (ret)
1057 goto err;
1058
1059 /* Adapt the phandle values in fdto to the above increase */
1060 ret = overlay_update_local_references(fdto, delta);
1061 if (ret)
1062 goto err;
1063
1064 /* Update fdto's phandles using symbols from fdt */
1065 ret = overlay_fixup_phandles(fdt, fdto);
1066 if (ret)
1067 goto err;
1068
1069 /* Don't overwrite phandles in fdt */
1070 ret = overlay_prevent_phandle_overwrite(fdt, fdto);
1071 if (ret)
1072 goto err;
1073
1074 ret = overlay_merge(fdt, fdto);
1075 if (ret)
1076 goto err;
1077
1078 ret = overlay_symbol_update(fdt, fdto);
1079 if (ret)
1080 goto err;
1081
1082 /*
1083 * The overlay has been damaged, erase its magic.
1084 */
1085 fdt_set_magic(fdto, ~0);
1086
1087 return 0;
1088
1089err:
1090 /*
1091 * The overlay might have been damaged, erase its magic.
1092 */
1093 fdt_set_magic(fdto, ~0);
1094
1095 /*
1096 * The base device tree might have been damaged, erase its
1097 * magic.
1098 */
1099 fdt_set_magic(fdt, ~0);
1100
1101 return ret;
1102}