summaryrefslogtreecommitdiff
path: root/drivers/of/overlay.c
blob: bd8ff4df723da217fda5ef25b9ad5b870a67bdb1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
// SPDX-License-Identifier: GPL-2.0
/*
 * Functions for working with device tree overlays
 *
 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
 * Copyright (C) 2012 Texas Instruments Inc.
 */

#define pr_fmt(fmt)	"OF: overlay: " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_fdt.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/libfdt.h>
#include <linux/err.h>
#include <linux/idr.h>

#include "of_private.h"

/**
 * struct target - info about current target node as recursing through overlay
 * @np:			node where current level of overlay will be applied
 * @in_livetree:	@np is a node in the live devicetree
 *
 * Used in the algorithm to create the portion of a changeset that describes
 * an overlay fragment, which is a devicetree subtree.  Initially @np is a node
 * in the live devicetree where the overlay subtree is targeted to be grafted
 * into.  When recursing to the next level of the overlay subtree, the target
 * also recurses to the next level of the live devicetree, as long as overlay
 * subtree node also exists in the live devicetree.  When a node in the overlay
 * subtree does not exist at the same level in the live devicetree, target->np
 * points to a newly allocated node, and all subsequent targets in the subtree
 * will be newly allocated nodes.
 */
struct target {
	struct device_node *np;
	bool in_livetree;
};

/**
 * struct fragment - info about fragment nodes in overlay expanded device tree
 * @target:	target of the overlay operation
 * @overlay:	pointer to the __overlay__ node
 */
struct fragment {
	struct device_node *overlay;
	struct device_node *target;
};

/**
 * struct overlay_changeset
 * @id:			changeset identifier
 * @ovcs_list:		list on which we are located
 * @new_fdt:		Memory allocated to hold unflattened aligned FDT
 * @overlay_mem:	the memory chunk that contains @overlay_root
 * @overlay_root:	expanded device tree that contains the fragment nodes
 * @notify_state:	most recent notify action used on overlay
 * @count:		count of fragment structures
 * @fragments:		fragment nodes in the overlay expanded device tree
 * @symbols_fragment:	last element of @fragments[] is the  __symbols__ node
 * @cset:		changeset to apply fragments to live device tree
 */
struct overlay_changeset {
	int id;
	struct list_head ovcs_list;
	const void *new_fdt;
	const void *overlay_mem;
	struct device_node *overlay_root;
	enum of_overlay_notify_action notify_state;
	int count;
	struct fragment *fragments;
	bool symbols_fragment;
	struct of_changeset cset;
};

/* flags are sticky - once set, do not reset */
static int devicetree_state_flags;
#define DTSF_APPLY_FAIL		0x01
#define DTSF_REVERT_FAIL	0x02

/*
 * If a changeset apply or revert encounters an error, an attempt will
 * be made to undo partial changes, but may fail.  If the undo fails
 * we do not know the state of the devicetree.
 */
static int devicetree_corrupt(void)
{
	return devicetree_state_flags &
		(DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
}

static int build_changeset_next_level(struct overlay_changeset *ovcs,
		struct target *target, const struct device_node *overlay_node);

/*
 * of_resolve_phandles() finds the largest phandle in the live tree.
 * of_overlay_apply() may add a larger phandle to the live tree.
 * Do not allow race between two overlays being applied simultaneously:
 *    mutex_lock(&of_overlay_phandle_mutex)
 *    of_resolve_phandles()
 *    of_overlay_apply()
 *    mutex_unlock(&of_overlay_phandle_mutex)
 */
static DEFINE_MUTEX(of_overlay_phandle_mutex);

void of_overlay_mutex_lock(void)
{
	mutex_lock(&of_overlay_phandle_mutex);
}

void of_overlay_mutex_unlock(void)
{
	mutex_unlock(&of_overlay_phandle_mutex);
}

static LIST_HEAD(ovcs_list);
static DEFINE_IDR(ovcs_idr);

static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);

/**
 * of_overlay_notifier_register() - Register notifier for overlay operations
 * @nb:		Notifier block to register
 *
 * Register for notification on overlay operations on device tree nodes. The
 * reported actions definied by @of_reconfig_change. The notifier callback
 * furthermore receives a pointer to the affected device tree node.
 *
 * Note that a notifier callback is not supposed to store pointers to a device
 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
 * respective node it received.
 */
int of_overlay_notifier_register(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&overlay_notify_chain, nb);
}
EXPORT_SYMBOL_GPL(of_overlay_notifier_register);

/**
 * of_overlay_notifier_unregister() - Unregister notifier for overlay operations
 * @nb:		Notifier block to unregister
 */
int of_overlay_notifier_unregister(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
}
EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);

static int overlay_notify(struct overlay_changeset *ovcs,
		enum of_overlay_notify_action action)
{
	struct of_overlay_notify_data nd;
	int i, ret;

	ovcs->notify_state = action;

	for (i = 0; i < ovcs->count; i++) {
		struct fragment *fragment = &ovcs->fragments[i];

		nd.target = fragment->target;
		nd.overlay = fragment->overlay;

		ret = blocking_notifier_call_chain(&overlay_notify_chain,
						   action, &nd);
		if (notifier_to_errno(ret)) {
			ret = notifier_to_errno(ret);
			pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
			       of_overlay_action_name(action), ret, nd.target);
			return ret;
		}
	}

	return 0;
}

/*
 * The values of properties in the "/__symbols__" node are paths in
 * the ovcs->overlay_root.  When duplicating the properties, the paths
 * need to be adjusted to be the correct path for the live device tree.
 *
 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
 * where symbol_path_tail can be a single node or it may be a multi-node path.
 *
 * The duplicated property value will be modified by replacing the
 * "/fragment_name/__overlay/" portion of the value  with the target
 * path from the fragment node.
 */
static struct property *dup_and_fixup_symbol_prop(
		struct overlay_changeset *ovcs, const struct property *prop)
{
	struct fragment *fragment;
	struct property *new_prop;
	struct device_node *fragment_node;
	struct device_node *overlay_node;
	const char *path;
	const char *path_tail;
	const char *target_path;
	int k;
	int overlay_name_len;
	int path_len;
	int path_tail_len;
	int target_path_len;

	if (!prop->value)
		return NULL;
	if (strnlen(prop->value, prop->length) >= prop->length)
		return NULL;
	path = prop->value;
	path_len = strlen(path);

	if (path_len < 1)
		return NULL;
	fragment_node = __of_find_node_by_path(ovcs->overlay_root, path + 1);
	overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
	of_node_put(fragment_node);
	of_node_put(overlay_node);

	for (k = 0; k < ovcs->count; k++) {
		fragment = &ovcs->fragments[k];
		if (fragment->overlay == overlay_node)
			break;
	}
	if (k >= ovcs->count)
		return NULL;

	overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);

	if (overlay_name_len > path_len)
		return NULL;
	path_tail = path + overlay_name_len;
	path_tail_len = strlen(path_tail);

	target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
	if (!target_path)
		return NULL;
	target_path_len = strlen(target_path);

	new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
	if (!new_prop)
		goto err_free_target_path;

	new_prop->name = kstrdup(prop->name, GFP_KERNEL);
	new_prop->length = target_path_len + path_tail_len + 1;
	new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
	if (!new_prop->name || !new_prop->value)
		goto err_free_new_prop;

	strcpy(new_prop->value, target_path);
	strcpy(new_prop->value + target_path_len, path_tail);

	of_property_set_flag(new_prop, OF_DYNAMIC);

	kfree(target_path);

	return new_prop;

err_free_new_prop:
	kfree(new_prop->name);
	kfree(new_prop->value);
	kfree(new_prop);
err_free_target_path:
	kfree(target_path);

	return NULL;
}

/**
 * add_changeset_property() - add @overlay_prop to overlay changeset
 * @ovcs:		overlay changeset
 * @target:		where @overlay_prop will be placed
 * @overlay_prop:	property to add or update, from overlay tree
 * @is_symbols_prop:	1 if @overlay_prop is from node "/__symbols__"
 *
 * If @overlay_prop does not already exist in live devicetree, add changeset
 * entry to add @overlay_prop in @target, else add changeset entry to update
 * value of @overlay_prop.
 *
 * @target may be either in the live devicetree or in a new subtree that
 * is contained in the changeset.
 *
 * Some special properties are not added or updated (no error returned):
 * "name", "phandle", "linux,phandle".
 *
 * Properties "#address-cells" and "#size-cells" are not updated if they
 * are already in the live tree, but if present in the live tree, the values
 * in the overlay must match the values in the live tree.
 *
 * Update of property in symbols node is not allowed.
 *
 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
 * invalid @overlay.
 */
static int add_changeset_property(struct overlay_changeset *ovcs,
		struct target *target, struct property *overlay_prop,
		bool is_symbols_prop)
{
	struct property *new_prop = NULL, *prop;
	int ret = 0;

	if (target->in_livetree)
		if (!of_prop_cmp(overlay_prop->name, "name") ||
		    !of_prop_cmp(overlay_prop->name, "phandle") ||
		    !of_prop_cmp(overlay_prop->name, "linux,phandle"))
			return 0;

	if (target->in_livetree)
		prop = of_find_property(target->np, overlay_prop->name, NULL);
	else
		prop = NULL;

	if (prop) {
		if (!of_prop_cmp(prop->name, "#address-cells")) {
			if (!of_prop_val_eq(prop, overlay_prop)) {
				pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
				       target->np);
				ret = -EINVAL;
			}
			return ret;

		} else if (!of_prop_cmp(prop->name, "#size-cells")) {
			if (!of_prop_val_eq(prop, overlay_prop)) {
				pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
				       target->np);
				ret = -EINVAL;
			}
			return ret;
		}
	}

	if (is_symbols_prop) {
		if (prop)
			return -EINVAL;
		new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
	} else {
		new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
	}

	if (!new_prop)
		return -ENOMEM;

	if (!prop) {
		if (!target->in_livetree) {
			new_prop->next = target->np->deadprops;
			target->np->deadprops = new_prop;
		}
		ret = of_changeset_add_property(&ovcs->cset, target->np,
						new_prop);
	} else {
		ret = of_changeset_update_property(&ovcs->cset, target->np,
						   new_prop);
	}

	if (!of_node_check_flag(target->np, OF_OVERLAY))
		pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n",
		       target->np, new_prop->name);

	if (ret) {
		kfree(new_prop->name);
		kfree(new_prop->value);
		kfree(new_prop);
	}
	return ret;
}

/**
 * add_changeset_node() - add @node (and children) to overlay changeset
 * @ovcs:	overlay changeset
 * @target:	where @node will be placed in live tree or changeset
 * @node:	node from within overlay device tree fragment
 *
 * If @node does not already exist in @target, add changeset entry
 * to add @node in @target.
 *
 * If @node already exists in @target, and the existing node has
 * a phandle, the overlay node is not allowed to have a phandle.
 *
 * If @node has child nodes, add the children recursively via
 * build_changeset_next_level().
 *
 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
 *       not contain the full path in node->full_name.  Thus an overlay
 *       created from an FDT also will not contain the full path in
 *       node->full_name.  However, a live devicetree created from Open
 *       Firmware may have the full path in node->full_name.
 *
 *       add_changeset_node() follows the FDT convention and does not include
 *       the full path in node->full_name.  Even though it expects the overlay
 *       to not contain the full path, it uses kbasename() to remove the
 *       full path should it exist.  It also uses kbasename() in comparisons
 *       to nodes in the live devicetree so that it can apply an overlay to
 *       a live devicetree created from Open Firmware.
 *
 * NOTE_2: Multiple mods of created nodes not supported.
 *
 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
 * invalid @overlay.
 */
static int add_changeset_node(struct overlay_changeset *ovcs,
		struct target *target, struct device_node *node)
{
	const char *node_kbasename;
	const __be32 *phandle;
	struct device_node *tchild;
	struct target target_child;
	int ret = 0, size;

	node_kbasename = kbasename(node->full_name);

	for_each_child_of_node(target->np, tchild)
		if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
			break;

	if (!tchild) {
		tchild = __of_node_dup(NULL, node_kbasename);
		if (!tchild)
			return -ENOMEM;

		tchild->parent = target->np;
		tchild->name = __of_get_property(node, "name", NULL);

		if (!tchild->name)
			tchild->name = "<NULL>";

		/* ignore obsolete "linux,phandle" */
		phandle = __of_get_property(node, "phandle", &size);
		if (phandle && (size == 4))
			tchild->phandle = be32_to_cpup(phandle);

		of_node_set_flag(tchild, OF_OVERLAY);

		ret = of_changeset_attach_node(&ovcs->cset, tchild);
		if (ret)
			return ret;

		target_child.np = tchild;
		target_child.in_livetree = false;

		ret = build_changeset_next_level(ovcs, &target_child, node);
		of_node_put(tchild);
		return ret;
	}

	if (node->phandle && tchild->phandle) {
		ret = -EINVAL;
	} else {
		target_child.np = tchild;
		target_child.in_livetree = target->in_livetree;
		ret = build_changeset_next_level(ovcs, &target_child, node);
	}
	of_node_put(tchild);

	return ret;
}

/**
 * build_changeset_next_level() - add level of overlay changeset
 * @ovcs:		overlay changeset
 * @target:		where to place @overlay_node in live tree
 * @overlay_node:	node from within an overlay device tree fragment
 *
 * Add the properties (if any) and nodes (if any) from @overlay_node to the
 * @ovcs->cset changeset.  If an added node has child nodes, they will
 * be added recursively.
 *
 * Do not allow symbols node to have any children.
 *
 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
 * invalid @overlay_node.
 */
static int build_changeset_next_level(struct overlay_changeset *ovcs,
		struct target *target, const struct device_node *overlay_node)
{
	struct device_node *child;
	struct property *prop;
	int ret;

	for_each_property_of_node(overlay_node, prop) {
		ret = add_changeset_property(ovcs, target, prop, 0);
		if (ret) {
			pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
				 target->np, prop->name, ret);
			return ret;
		}
	}

	for_each_child_of_node(overlay_node, child) {
		ret = add_changeset_node(ovcs, target, child);
		if (ret) {
			pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n",
				 target->np, child, ret);
			of_node_put(child);
			return ret;
		}
	}

	return 0;
}

/*
 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
 */
static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
		struct target *target,
		const struct device_node *overlay_symbols_node)
{
	struct property *prop;
	int ret;

	for_each_property_of_node(overlay_symbols_node, prop) {
		ret = add_changeset_property(ovcs, target, prop, 1);
		if (ret) {
			pr_debug("Failed to apply symbols prop @%pOF/%s, err=%d\n",
				 target->np, prop->name, ret);
			return ret;
		}
	}

	return 0;
}

static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
		struct of_changeset_entry *ce_1)
{
	struct of_changeset_entry *ce_2;
	char *fn_1, *fn_2;
	int node_path_match;

	if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
	    ce_1->action != OF_RECONFIG_DETACH_NODE)
		return 0;

	ce_2 = ce_1;
	list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
		if ((ce_2->action != OF_RECONFIG_ATTACH_NODE &&
		     ce_2->action != OF_RECONFIG_DETACH_NODE) ||
		    of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
			continue;

		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
		node_path_match = !strcmp(fn_1, fn_2);
		kfree(fn_1);
		kfree(fn_2);
		if (node_path_match) {
			pr_err("ERROR: multiple fragments add and/or delete node %pOF\n",
			       ce_1->np);
			return -EINVAL;
		}
	}

	return 0;
}

static int find_dup_cset_prop(struct overlay_changeset *ovcs,
		struct of_changeset_entry *ce_1)
{
	struct of_changeset_entry *ce_2;
	char *fn_1, *fn_2;
	int node_path_match;

	if (ce_1->action != OF_RECONFIG_ADD_PROPERTY &&
	    ce_1->action != OF_RECONFIG_REMOVE_PROPERTY &&
	    ce_1->action != OF_RECONFIG_UPDATE_PROPERTY)
		return 0;

	ce_2 = ce_1;
	list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
		if ((ce_2->action != OF_RECONFIG_ADD_PROPERTY &&
		     ce_2->action != OF_RECONFIG_REMOVE_PROPERTY &&
		     ce_2->action != OF_RECONFIG_UPDATE_PROPERTY) ||
		    of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
			continue;

		fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
		fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
		node_path_match = !strcmp(fn_1, fn_2);
		kfree(fn_1);
		kfree(fn_2);
		if (node_path_match &&
		    !of_prop_cmp(ce_1->prop->name, ce_2->prop->name)) {
			pr_err("ERROR: multiple fragments add, update, and/or delete property %pOF/%s\n",
			       ce_1->np, ce_1->prop->name);
			return -EINVAL;
		}
	}

	return 0;
}

/**
 * changeset_dup_entry_check() - check for duplicate entries
 * @ovcs:	Overlay changeset
 *
 * Check changeset @ovcs->cset for multiple {add or delete} node entries for
 * the same node or duplicate {add, delete, or update} properties entries
 * for the same property.
 *
 * Return: 0 on success, or -EINVAL if duplicate changeset entry found.
 */
static int changeset_dup_entry_check(struct overlay_changeset *ovcs)
{
	struct of_changeset_entry *ce_1;
	int dup_entry = 0;

	list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
		dup_entry |= find_dup_cset_node_entry(ovcs, ce_1);
		dup_entry |= find_dup_cset_prop(ovcs, ce_1);
	}

	return dup_entry ? -EINVAL : 0;
}

/**
 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
 * @ovcs:	Overlay changeset
 *
 * Create changeset @ovcs->cset to contain the nodes and properties of the
 * overlay device tree fragments in @ovcs->fragments[].  If an error occurs,
 * any portions of the changeset that were successfully created will remain
 * in @ovcs->cset.
 *
 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
 * invalid overlay in @ovcs->fragments[].
 */
static int build_changeset(struct overlay_changeset *ovcs)
{
	struct fragment *fragment;
	struct target target;
	int fragments_count, i, ret;

	/*
	 * if there is a symbols fragment in ovcs->fragments[i] it is
	 * the final element in the array
	 */
	if (ovcs->symbols_fragment)
		fragments_count = ovcs->count - 1;
	else
		fragments_count = ovcs->count;

	for (i = 0; i < fragments_count; i++) {
		fragment = &ovcs->fragments[i];

		target.np = fragment->target;
		target.in_livetree = true;
		ret = build_changeset_next_level(ovcs, &target,
						 fragment->overlay);
		if (ret) {
			pr_debug("fragment apply failed '%pOF'\n",
				 fragment->target);
			return ret;
		}
	}

	if (ovcs->symbols_fragment) {
		fragment = &ovcs->fragments[ovcs->count - 1];

		target.np = fragment->target;
		target.in_livetree = true;
		ret = build_changeset_symbols_node(ovcs, &target,
						   fragment->overlay);
		if (ret) {
			pr_debug("symbols fragment apply failed '%pOF'\n",
				 fragment->target);
			return ret;
		}
	}

	return changeset_dup_entry_check(ovcs);
}

/*
 * Find the target node using a number of different strategies
 * in order of preference:
 *
 * 1) "target" property containing the phandle of the target
 * 2) "target-path" property containing the path of the target
 */
static struct device_node *find_target(struct device_node *info_node)
{
	struct device_node *node;
	const char *path;
	u32 val;
	int ret;

	ret = of_property_read_u32(info_node, "target", &val);
	if (!ret) {
		node = of_find_node_by_phandle(val);
		if (!node)
			pr_err("find target, node: %pOF, phandle 0x%x not found\n",
			       info_node, val);
		return node;
	}

	ret = of_property_read_string(info_node, "target-path", &path);
	if (!ret) {
		node =  of_find_node_by_path(path);
		if (!node)
			pr_err("find target, node: %pOF, path '%s' not found\n",
			       info_node, path);
		return node;
	}

	pr_err("find target, node: %pOF, no target property\n", info_node);

	return NULL;
}

/**
 * init_overlay_changeset() - initialize overlay changeset from overlay tree
 * @ovcs:		Overlay changeset to build
 *
 * Initialize @ovcs.  Populate @ovcs->fragments with node information from
 * the top level of @overlay_root.  The relevant top level nodes are the
 * fragment nodes and the __symbols__ node.  Any other top level node will
 * be ignored.  Populate other @ovcs fields.
 *
 * Return: 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
 * detected in @overlay_root.  On error return, the caller of
 * init_overlay_changeset() must call free_overlay_changeset().
 */
static int init_overlay_changeset(struct overlay_changeset *ovcs)
{
	struct device_node *node, *overlay_node;
	struct fragment *fragment;
	struct fragment *fragments;
	int cnt, ret;

	/*
	 * None of the resources allocated by this function will be freed in
	 * the error paths.  Instead the caller of this function is required
	 * to call free_overlay_changeset() (which will free the resources)
	 * if error return.
	 */

	/*
	 * Warn for some issues.  Can not return -EINVAL for these until
	 * of_unittest_apply_overlay() is fixed to pass these checks.
	 */
	if (!of_node_check_flag(ovcs->overlay_root, OF_DYNAMIC))
		pr_debug("%s() ovcs->overlay_root is not dynamic\n", __func__);

	if (!of_node_check_flag(ovcs->overlay_root, OF_DETACHED))
		pr_debug("%s() ovcs->overlay_root is not detached\n", __func__);

	if (!of_node_is_root(ovcs->overlay_root))
		pr_debug("%s() ovcs->overlay_root is not root\n", __func__);

	of_changeset_init(&ovcs->cset);

	cnt = 0;

	/* fragment nodes */
	for_each_child_of_node(ovcs->overlay_root, node) {
		overlay_node = of_get_child_by_name(node, "__overlay__");
		if (overlay_node) {
			cnt++;
			of_node_put(overlay_node);
		}
	}

	node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
	if (node) {
		cnt++;
		of_node_put(node);
	}

	fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
	if (!fragments) {
		ret = -ENOMEM;
		goto err_out;
	}
	ovcs->fragments = fragments;

	cnt = 0;
	for_each_child_of_node(ovcs->overlay_root, node) {
		overlay_node = of_get_child_by_name(node, "__overlay__");
		if (!overlay_node)
			continue;

		fragment = &fragments[cnt];
		fragment->overlay = overlay_node;
		fragment->target = find_target(node);
		if (!fragment->target) {
			of_node_put(fragment->overlay);
			ret = -EINVAL;
			of_node_put(node);
			goto err_out;
		}

		cnt++;
	}

	/*
	 * if there is a symbols fragment in ovcs->fragments[i] it is
	 * the final element in the array
	 */
	node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
	if (node) {
		ovcs->symbols_fragment = 1;
		fragment = &fragments[cnt];
		fragment->overlay = node;
		fragment->target = of_find_node_by_path("/__symbols__");

		if (!fragment->target) {
			pr_err("symbols in overlay, but not in live tree\n");
			ret = -EINVAL;
			goto err_out;
		}

		cnt++;
	}

	if (!cnt) {
		pr_err("no fragments or symbols in overlay\n");
		ret = -EINVAL;
		goto err_out;
	}

	ovcs->count = cnt;

	return 0;

err_out:
	pr_err("%s() failed, ret = %d\n", __func__, ret);

	return ret;
}

static void free_overlay_changeset(struct overlay_changeset *ovcs)
{
	int i;

	if (ovcs->cset.entries.next)
		of_changeset_destroy(&ovcs->cset);

	if (ovcs->id) {
		idr_remove(&ovcs_idr, ovcs->id);
		list_del(&ovcs->ovcs_list);
		ovcs->id = 0;
	}


	for (i = 0; i < ovcs->count; i++) {
		of_node_put(ovcs->fragments[i].target);
		of_node_put(ovcs->fragments[i].overlay);
	}
	kfree(ovcs->fragments);

	/*
	 * There should be no live pointers into ovcs->overlay_mem and
	 * ovcs->new_fdt due to the policy that overlay notifiers are not
	 * allowed to retain pointers into the overlay devicetree other
	 * than during the window from OF_OVERLAY_PRE_APPLY overlay
	 * notifiers until the OF_OVERLAY_POST_REMOVE overlay notifiers.
	 *
	 * A memory leak will occur here if within the window.
	 */

	if (ovcs->notify_state == OF_OVERLAY_INIT ||
	    ovcs->notify_state == OF_OVERLAY_POST_REMOVE) {
		kfree(ovcs->overlay_mem);
		kfree(ovcs->new_fdt);
	}
	kfree(ovcs);
}

/*
 * internal documentation
 *
 * of_overlay_apply() - Create and apply an overlay changeset
 * @ovcs:	overlay changeset
 *
 * Creates and applies an overlay changeset.
 *
 * If an error is returned by an overlay changeset pre-apply notifier
 * then no further overlay changeset pre-apply notifier will be called.
 *
 * If an error is returned by an overlay changeset post-apply notifier
 * then no further overlay changeset post-apply notifier will be called.
 *
 * If more than one notifier returns an error, then the last notifier
 * error to occur is returned.
 *
 * If an error occurred while applying the overlay changeset, then an
 * attempt is made to revert any changes that were made to the
 * device tree.  If there were any errors during the revert attempt
 * then the state of the device tree can not be determined, and any
 * following attempt to apply or remove an overlay changeset will be
 * refused.
 *
 * Returns 0 on success, or a negative error number.  On error return,
 * the caller of of_overlay_apply() must call free_overlay_changeset().
 */

static int of_overlay_apply(struct overlay_changeset *ovcs)
{
	int ret = 0, ret_revert, ret_tmp;

	ret = of_resolve_phandles(ovcs->overlay_root);
	if (ret)
		goto out;

	ret = init_overlay_changeset(ovcs);
	if (ret)
		goto out;

	ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
	if (ret)
		goto out;

	ret = build_changeset(ovcs);
	if (ret)
		goto out;

	ret_revert = 0;
	ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
	if (ret) {
		if (ret_revert) {
			pr_debug("overlay changeset revert error %d\n",
				 ret_revert);
			devicetree_state_flags |= DTSF_APPLY_FAIL;
		}
		goto out;
	}

	ret = __of_changeset_apply_notify(&ovcs->cset);
	if (ret)
		pr_err("overlay apply changeset entry notify error %d\n", ret);
	/* notify failure is not fatal, continue */

	ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
	if (ret_tmp)
		if (!ret)
			ret = ret_tmp;

out:
	pr_debug("%s() err=%d\n", __func__, ret);

	return ret;
}

/*
 * of_overlay_fdt_apply() - Create and apply an overlay changeset
 * @overlay_fdt:	pointer to overlay FDT
 * @overlay_fdt_size:	number of bytes in @overlay_fdt
 * @ret_ovcs_id:	pointer for returning created changeset id
 *
 * Creates and applies an overlay changeset.
 *
 * See of_overlay_apply() for important behavior information.
 *
 * Return: 0 on success, or a negative error number.  *@ret_ovcs_id is set to
 * the value of overlay changeset id, which can be passed to of_overlay_remove()
 * to remove the overlay.
 *
 * On error return, the changeset may be partially applied.  This is especially
 * likely if an OF_OVERLAY_POST_APPLY notifier returns an error.  In this case
 * the caller should call of_overlay_remove() with the value in *@ret_ovcs_id.
 */

int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
			 int *ret_ovcs_id)
{
	void *new_fdt;
	void *new_fdt_align;
	void *overlay_mem;
	int ret;
	u32 size;
	struct overlay_changeset *ovcs;

	*ret_ovcs_id = 0;

	if (devicetree_corrupt()) {
		pr_err("devicetree state suspect, refuse to apply overlay\n");
		return -EBUSY;
	}

	if (overlay_fdt_size < sizeof(struct fdt_header) ||
	    fdt_check_header(overlay_fdt)) {
		pr_err("Invalid overlay_fdt header\n");
		return -EINVAL;
	}

	size = fdt_totalsize(overlay_fdt);
	if (overlay_fdt_size < size)
		return -EINVAL;

	ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
	if (!ovcs)
		return -ENOMEM;

	of_overlay_mutex_lock();
	mutex_lock(&of_mutex);

	/*
	 * ovcs->notify_state must be set to OF_OVERLAY_INIT before allocating
	 * ovcs resources, implicitly set by kzalloc() of ovcs
	 */

	ovcs->id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
	if (ovcs->id <= 0) {
		ret = ovcs->id;
		goto err_free_ovcs;
	}

	INIT_LIST_HEAD(&ovcs->ovcs_list);
	list_add_tail(&ovcs->ovcs_list, &ovcs_list);

	/*
	 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
	 * will create pointers to the passed in FDT in the unflattened tree.
	 */
	new_fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
	if (!new_fdt) {
		ret = -ENOMEM;
		goto err_free_ovcs;
	}
	ovcs->new_fdt = new_fdt;

	new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
	memcpy(new_fdt_align, overlay_fdt, size);

	overlay_mem = of_fdt_unflatten_tree(new_fdt_align, NULL,
					    &ovcs->overlay_root);
	if (!overlay_mem) {
		pr_err("unable to unflatten overlay_fdt\n");
		ret = -EINVAL;
		goto err_free_ovcs;
	}
	ovcs->overlay_mem = overlay_mem;

	ret = of_overlay_apply(ovcs);
	/*
	 * If of_overlay_apply() error, calling free_overlay_changeset() may
	 * result in a memory leak if the apply partly succeeded, so do NOT
	 * goto err_free_ovcs.  Instead, the caller of of_overlay_fdt_apply()
	 * can call of_overlay_remove();
	 */
	*ret_ovcs_id = ovcs->id;
	goto out_unlock;

err_free_ovcs:
	free_overlay_changeset(ovcs);

out_unlock:
	mutex_unlock(&of_mutex);
	of_overlay_mutex_unlock();
	return ret;
}
EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);

/*
 * Find @np in @tree.
 *
 * Returns 1 if @np is @tree or is contained in @tree, else 0
 */
static int find_node(struct device_node *tree, struct device_node *np)
{
	struct device_node *child;

	if (tree == np)
		return 1;

	for_each_child_of_node(tree, child) {
		if (find_node(child, np)) {
			of_node_put(child);
			return 1;
		}
	}

	return 0;
}

/*
 * Is @remove_ce_node a child of, a parent of, or the same as any
 * node in an overlay changeset more topmost than @remove_ovcs?
 *
 * Returns 1 if found, else 0
 */
static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
		struct device_node *remove_ce_node)
{
	struct overlay_changeset *ovcs;
	struct of_changeset_entry *ce;

	list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
		if (ovcs == remove_ovcs)
			break;

		list_for_each_entry(ce, &ovcs->cset.entries, node) {
			if (find_node(ce->np, remove_ce_node)) {
				pr_err("%s: #%d overlaps with #%d @%pOF\n",
					__func__, remove_ovcs->id, ovcs->id,
					remove_ce_node);
				return 1;
			}
			if (find_node(remove_ce_node, ce->np)) {
				pr_err("%s: #%d overlaps with #%d @%pOF\n",
					__func__, remove_ovcs->id, ovcs->id,
					remove_ce_node);
				return 1;
			}
		}
	}

	return 0;
}

/*
 * We can safely remove the overlay only if it's the top-most one.
 * Newly applied overlays are inserted at the tail of the overlay list,
 * so a top most overlay is the one that is closest to the tail.
 *
 * The topmost check is done by exploiting this property. For each
 * affected device node in the log list we check if this overlay is
 * the one closest to the tail. If another overlay has affected this
 * device node and is closest to the tail, then removal is not permited.
 */
static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
{
	struct of_changeset_entry *remove_ce;

	list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
		if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
			pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
			return 0;
		}
	}

	return 1;
}

/**
 * of_overlay_remove() - Revert and free an overlay changeset
 * @ovcs_id:	Pointer to overlay changeset id
 *
 * Removes an overlay if it is permissible.  @ovcs_id was previously returned
 * by of_overlay_fdt_apply().
 *
 * If an error occurred while attempting to revert the overlay changeset,
 * then an attempt is made to re-apply any changeset entry that was
 * reverted.  If an error occurs on re-apply then the state of the device
 * tree can not be determined, and any following attempt to apply or remove
 * an overlay changeset will be refused.
 *
 * A non-zero return value will not revert the changeset if error is from:
 *   - parameter checks
 *   - overlay changeset pre-remove notifier
 *   - overlay changeset entry revert
 *
 * If an error is returned by an overlay changeset pre-remove notifier
 * then no further overlay changeset pre-remove notifier will be called.
 *
 * If more than one notifier returns an error, then the last notifier
 * error to occur is returned.
 *
 * A non-zero return value will revert the changeset if error is from:
 *   - overlay changeset entry notifier
 *   - overlay changeset post-remove notifier
 *
 * If an error is returned by an overlay changeset post-remove notifier
 * then no further overlay changeset post-remove notifier will be called.
 *
 * Return: 0 on success, or a negative error number.  *@ovcs_id is set to
 * zero after reverting the changeset, even if a subsequent error occurs.
 */
int of_overlay_remove(int *ovcs_id)
{
	struct overlay_changeset *ovcs;
	int ret, ret_apply, ret_tmp;

	if (devicetree_corrupt()) {
		pr_err("suspect devicetree state, refuse to remove overlay\n");
		ret = -EBUSY;
		goto out;
	}

	mutex_lock(&of_mutex);

	ovcs = idr_find(&ovcs_idr, *ovcs_id);
	if (!ovcs) {
		ret = -ENODEV;
		pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
		goto err_unlock;
	}

	if (!overlay_removal_is_ok(ovcs)) {
		ret = -EBUSY;
		goto err_unlock;
	}

	ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
	if (ret)
		goto err_unlock;

	ret_apply = 0;
	ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
	if (ret) {
		if (ret_apply)
			devicetree_state_flags |= DTSF_REVERT_FAIL;
		goto err_unlock;
	}

	ret = __of_changeset_revert_notify(&ovcs->cset);
	if (ret)
		pr_err("overlay remove changeset entry notify error %d\n", ret);
	/* notify failure is not fatal, continue */

	*ovcs_id = 0;

	/*
	 * Note that the overlay memory will be kfree()ed by
	 * free_overlay_changeset() even if the notifier for
	 * OF_OVERLAY_POST_REMOVE returns an error.
	 */
	ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
	if (ret_tmp)
		if (!ret)
			ret = ret_tmp;

	free_overlay_changeset(ovcs);

err_unlock:
	/*
	 * If jumped over free_overlay_changeset(), then did not kfree()
	 * overlay related memory.  This is a memory leak unless a subsequent
	 * of_overlay_remove() of this overlay is successful.
	 */
	mutex_unlock(&of_mutex);

out:
	pr_debug("%s() err=%d\n", __func__, ret);

	return ret;
}
EXPORT_SYMBOL_GPL(of_overlay_remove);

/**
 * of_overlay_remove_all() - Reverts and frees all overlay changesets
 *
 * Removes all overlays from the system in the correct order.
 *
 * Return: 0 on success, or a negative error number
 */
int of_overlay_remove_all(void)
{
	struct overlay_changeset *ovcs, *ovcs_n;
	int ret;

	/* the tail of list is guaranteed to be safe to remove */
	list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
		ret = of_overlay_remove(&ovcs->id);
		if (ret)
			return ret;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(of_overlay_remove_all);