summaryrefslogtreecommitdiff
path: root/fs/debugfs/file.c
blob: c6f4a9a98b85353686b50b98e57d3263a2dfbc47 (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
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
// SPDX-License-Identifier: GPL-2.0
/*
 *  file.c - part of debugfs, a tiny little debug file system
 *
 *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
 *  Copyright (C) 2004 IBM Inc.
 *
 *  debugfs is for people to use instead of /proc or /sys.
 *  See Documentation/filesystems/ for more details.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/debugfs.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>
#include <linux/poll.h>
#include <linux/security.h>

#include "internal.h"

struct poll_table_struct;

static ssize_t default_read_file(struct file *file, char __user *buf,
				 size_t count, loff_t *ppos)
{
	return 0;
}

static ssize_t default_write_file(struct file *file, const char __user *buf,
				   size_t count, loff_t *ppos)
{
	return count;
}

const struct file_operations debugfs_noop_file_operations = {
	.read =		default_read_file,
	.write =	default_write_file,
	.open =		simple_open,
	.llseek =	noop_llseek,
};

#define F_DENTRY(filp) ((filp)->f_path.dentry)

const struct file_operations *debugfs_real_fops(const struct file *filp)
{
	struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata;

	if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) {
		/*
		 * Urgh, we've been called w/o a protecting
		 * debugfs_file_get().
		 */
		WARN_ON(1);
		return NULL;
	}

	return fsd->real_fops;
}
EXPORT_SYMBOL_GPL(debugfs_real_fops);

/**
 * debugfs_file_get - mark the beginning of file data access
 * @dentry: the dentry object whose data is being accessed.
 *
 * Up to a matching call to debugfs_file_put(), any successive call
 * into the file removing functions debugfs_remove() and
 * debugfs_remove_recursive() will block. Since associated private
 * file data may only get freed after a successful return of any of
 * the removal functions, you may safely access it after a successful
 * call to debugfs_file_get() without worrying about lifetime issues.
 *
 * If -%EIO is returned, the file has already been removed and thus,
 * it is not safe to access any of its data. If, on the other hand,
 * it is allowed to access the file data, zero is returned.
 */
int debugfs_file_get(struct dentry *dentry)
{
	struct debugfs_fsdata *fsd;
	void *d_fsd;

	/*
	 * This could only happen if some debugfs user erroneously calls
	 * debugfs_file_get() on a dentry that isn't even a file, let
	 * them know about it.
	 */
	if (WARN_ON(!d_is_reg(dentry)))
		return -EINVAL;

	d_fsd = READ_ONCE(dentry->d_fsdata);
	if (!((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) {
		fsd = d_fsd;
	} else {
		fsd = kmalloc(sizeof(*fsd), GFP_KERNEL);
		if (!fsd)
			return -ENOMEM;

		fsd->real_fops = (void *)((unsigned long)d_fsd &
					~DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
		refcount_set(&fsd->active_users, 1);
		init_completion(&fsd->active_users_drained);
		INIT_LIST_HEAD(&fsd->cancellations);
		mutex_init(&fsd->cancellations_mtx);

		if (cmpxchg(&dentry->d_fsdata, d_fsd, fsd) != d_fsd) {
			mutex_destroy(&fsd->cancellations_mtx);
			kfree(fsd);
			fsd = READ_ONCE(dentry->d_fsdata);
		}
	}

	/*
	 * In case of a successful cmpxchg() above, this check is
	 * strictly necessary and must follow it, see the comment in
	 * __debugfs_remove_file().
	 * OTOH, if the cmpxchg() hasn't been executed or wasn't
	 * successful, this serves the purpose of not starving
	 * removers.
	 */
	if (d_unlinked(dentry))
		return -EIO;

	if (!refcount_inc_not_zero(&fsd->active_users))
		return -EIO;

	return 0;
}
EXPORT_SYMBOL_GPL(debugfs_file_get);

/**
 * debugfs_file_put - mark the end of file data access
 * @dentry: the dentry object formerly passed to
 *          debugfs_file_get().
 *
 * Allow any ongoing concurrent call into debugfs_remove() or
 * debugfs_remove_recursive() blocked by a former call to
 * debugfs_file_get() to proceed and return to its caller.
 */
void debugfs_file_put(struct dentry *dentry)
{
	struct debugfs_fsdata *fsd = READ_ONCE(dentry->d_fsdata);

	if (refcount_dec_and_test(&fsd->active_users))
		complete(&fsd->active_users_drained);
}
EXPORT_SYMBOL_GPL(debugfs_file_put);

/**
 * debugfs_enter_cancellation - enter a debugfs cancellation
 * @file: the file being accessed
 * @cancellation: the cancellation object, the cancel callback
 *	inside of it must be initialized
 *
 * When a debugfs file is removed it needs to wait for all active
 * operations to complete. However, the operation itself may need
 * to wait for hardware or completion of some asynchronous process
 * or similar. As such, it may need to be cancelled to avoid long
 * waits or even deadlocks.
 *
 * This function can be used inside a debugfs handler that may
 * need to be cancelled. As soon as this function is called, the
 * cancellation's 'cancel' callback may be called, at which point
 * the caller should proceed to call debugfs_leave_cancellation()
 * and leave the debugfs handler function as soon as possible.
 * Note that the 'cancel' callback is only ever called in the
 * context of some kind of debugfs_remove().
 *
 * This function must be paired with debugfs_leave_cancellation().
 */
void debugfs_enter_cancellation(struct file *file,
				struct debugfs_cancellation *cancellation)
{
	struct debugfs_fsdata *fsd;
	struct dentry *dentry = F_DENTRY(file);

	INIT_LIST_HEAD(&cancellation->list);

	if (WARN_ON(!d_is_reg(dentry)))
		return;

	if (WARN_ON(!cancellation->cancel))
		return;

	fsd = READ_ONCE(dentry->d_fsdata);
	if (WARN_ON(!fsd ||
		    ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)))
		return;

	mutex_lock(&fsd->cancellations_mtx);
	list_add(&cancellation->list, &fsd->cancellations);
	mutex_unlock(&fsd->cancellations_mtx);

	/* if we're already removing wake it up to cancel */
	if (d_unlinked(dentry))
		complete(&fsd->active_users_drained);
}
EXPORT_SYMBOL_GPL(debugfs_enter_cancellation);

/**
 * debugfs_leave_cancellation - leave cancellation section
 * @file: the file being accessed
 * @cancellation: the cancellation previously registered with
 *	debugfs_enter_cancellation()
 *
 * See the documentation of debugfs_enter_cancellation().
 */
void debugfs_leave_cancellation(struct file *file,
				struct debugfs_cancellation *cancellation)
{
	struct debugfs_fsdata *fsd;
	struct dentry *dentry = F_DENTRY(file);

	if (WARN_ON(!d_is_reg(dentry)))
		return;

	fsd = READ_ONCE(dentry->d_fsdata);
	if (WARN_ON(!fsd ||
		    ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)))
		return;

	mutex_lock(&fsd->cancellations_mtx);
	if (!list_empty(&cancellation->list))
		list_del(&cancellation->list);
	mutex_unlock(&fsd->cancellations_mtx);
}
EXPORT_SYMBOL_GPL(debugfs_leave_cancellation);

/*
 * Only permit access to world-readable files when the kernel is locked down.
 * We also need to exclude any file that has ways to write or alter it as root
 * can bypass the permissions check.
 */
static int debugfs_locked_down(struct inode *inode,
			       struct file *filp,
			       const struct file_operations *real_fops)
{
	if ((inode->i_mode & 07777 & ~0444) == 0 &&
	    !(filp->f_mode & FMODE_WRITE) &&
	    !real_fops->unlocked_ioctl &&
	    !real_fops->compat_ioctl &&
	    !real_fops->mmap)
		return 0;

	if (security_locked_down(LOCKDOWN_DEBUGFS))
		return -EPERM;

	return 0;
}

static int open_proxy_open(struct inode *inode, struct file *filp)
{
	struct dentry *dentry = F_DENTRY(filp);
	const struct file_operations *real_fops = NULL;
	int r;

	r = debugfs_file_get(dentry);
	if (r)
		return r == -EIO ? -ENOENT : r;

	real_fops = debugfs_real_fops(filp);

	r = debugfs_locked_down(inode, filp, real_fops);
	if (r)
		goto out;

	if (!fops_get(real_fops)) {
#ifdef CONFIG_MODULES
		if (real_fops->owner &&
		    real_fops->owner->state == MODULE_STATE_GOING) {
			r = -ENXIO;
			goto out;
		}
#endif

		/* Huh? Module did not clean up after itself at exit? */
		WARN(1, "debugfs file owner did not clean up at exit: %pd",
			dentry);
		r = -ENXIO;
		goto out;
	}
	replace_fops(filp, real_fops);

	if (real_fops->open)
		r = real_fops->open(inode, filp);

out:
	debugfs_file_put(dentry);
	return r;
}

const struct file_operations debugfs_open_proxy_file_operations = {
	.open = open_proxy_open,
};

#define PROTO(args...) args
#define ARGS(args...) args

#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args)		\
static ret_type full_proxy_ ## name(proto)				\
{									\
	struct dentry *dentry = F_DENTRY(filp);			\
	const struct file_operations *real_fops;			\
	ret_type r;							\
									\
	r = debugfs_file_get(dentry);					\
	if (unlikely(r))						\
		return r;						\
	real_fops = debugfs_real_fops(filp);				\
	r = real_fops->name(args);					\
	debugfs_file_put(dentry);					\
	return r;							\
}

FULL_PROXY_FUNC(llseek, loff_t, filp,
		PROTO(struct file *filp, loff_t offset, int whence),
		ARGS(filp, offset, whence));

FULL_PROXY_FUNC(read, ssize_t, filp,
		PROTO(struct file *filp, char __user *buf, size_t size,
			loff_t *ppos),
		ARGS(filp, buf, size, ppos));

FULL_PROXY_FUNC(write, ssize_t, filp,
		PROTO(struct file *filp, const char __user *buf, size_t size,
			loff_t *ppos),
		ARGS(filp, buf, size, ppos));

FULL_PROXY_FUNC(unlocked_ioctl, long, filp,
		PROTO(struct file *filp, unsigned int cmd, unsigned long arg),
		ARGS(filp, cmd, arg));

static __poll_t full_proxy_poll(struct file *filp,
				struct poll_table_struct *wait)
{
	struct dentry *dentry = F_DENTRY(filp);
	__poll_t r = 0;
	const struct file_operations *real_fops;

	if (debugfs_file_get(dentry))
		return EPOLLHUP;

	real_fops = debugfs_real_fops(filp);
	r = real_fops->poll(filp, wait);
	debugfs_file_put(dentry);
	return r;
}

static int full_proxy_release(struct inode *inode, struct file *filp)
{
	const struct dentry *dentry = F_DENTRY(filp);
	const struct file_operations *real_fops = debugfs_real_fops(filp);
	const struct file_operations *proxy_fops = filp->f_op;
	int r = 0;

	/*
	 * We must not protect this against removal races here: the
	 * original releaser should be called unconditionally in order
	 * not to leak any resources. Releasers must not assume that
	 * ->i_private is still being meaningful here.
	 */
	if (real_fops->release)
		r = real_fops->release(inode, filp);

	replace_fops(filp, d_inode(dentry)->i_fop);
	kfree(proxy_fops);
	fops_put(real_fops);
	return r;
}

static void __full_proxy_fops_init(struct file_operations *proxy_fops,
				const struct file_operations *real_fops)
{
	proxy_fops->release = full_proxy_release;
	if (real_fops->llseek)
		proxy_fops->llseek = full_proxy_llseek;
	if (real_fops->read)
		proxy_fops->read = full_proxy_read;
	if (real_fops->write)
		proxy_fops->write = full_proxy_write;
	if (real_fops->poll)
		proxy_fops->poll = full_proxy_poll;
	if (real_fops->unlocked_ioctl)
		proxy_fops->unlocked_ioctl = full_proxy_unlocked_ioctl;
}

static int full_proxy_open(struct inode *inode, struct file *filp)
{
	struct dentry *dentry = F_DENTRY(filp);
	const struct file_operations *real_fops = NULL;
	struct file_operations *proxy_fops = NULL;
	int r;

	r = debugfs_file_get(dentry);
	if (r)
		return r == -EIO ? -ENOENT : r;

	real_fops = debugfs_real_fops(filp);

	r = debugfs_locked_down(inode, filp, real_fops);
	if (r)
		goto out;

	if (!fops_get(real_fops)) {
#ifdef CONFIG_MODULES
		if (real_fops->owner &&
		    real_fops->owner->state == MODULE_STATE_GOING) {
			r = -ENXIO;
			goto out;
		}
#endif

		/* Huh? Module did not cleanup after itself at exit? */
		WARN(1, "debugfs file owner did not clean up at exit: %pd",
			dentry);
		r = -ENXIO;
		goto out;
	}

	proxy_fops = kzalloc(sizeof(*proxy_fops), GFP_KERNEL);
	if (!proxy_fops) {
		r = -ENOMEM;
		goto free_proxy;
	}
	__full_proxy_fops_init(proxy_fops, real_fops);
	replace_fops(filp, proxy_fops);

	if (real_fops->open) {
		r = real_fops->open(inode, filp);
		if (r) {
			replace_fops(filp, d_inode(dentry)->i_fop);
			goto free_proxy;
		} else if (filp->f_op != proxy_fops) {
			/* No protection against file removal anymore. */
			WARN(1, "debugfs file owner replaced proxy fops: %pd",
				dentry);
			goto free_proxy;
		}
	}

	goto out;
free_proxy:
	kfree(proxy_fops);
	fops_put(real_fops);
out:
	debugfs_file_put(dentry);
	return r;
}

const struct file_operations debugfs_full_proxy_file_operations = {
	.open = full_proxy_open,
};

ssize_t debugfs_attr_read(struct file *file, char __user *buf,
			size_t len, loff_t *ppos)
{
	struct dentry *dentry = F_DENTRY(file);
	ssize_t ret;

	ret = debugfs_file_get(dentry);
	if (unlikely(ret))
		return ret;
	ret = simple_attr_read(file, buf, len, ppos);
	debugfs_file_put(dentry);
	return ret;
}
EXPORT_SYMBOL_GPL(debugfs_attr_read);

static ssize_t debugfs_attr_write_xsigned(struct file *file, const char __user *buf,
			 size_t len, loff_t *ppos, bool is_signed)
{
	struct dentry *dentry = F_DENTRY(file);
	ssize_t ret;

	ret = debugfs_file_get(dentry);
	if (unlikely(ret))
		return ret;
	if (is_signed)
		ret = simple_attr_write_signed(file, buf, len, ppos);
	else
		ret = simple_attr_write(file, buf, len, ppos);
	debugfs_file_put(dentry);
	return ret;
}

ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
			 size_t len, loff_t *ppos)
{
	return debugfs_attr_write_xsigned(file, buf, len, ppos, false);
}
EXPORT_SYMBOL_GPL(debugfs_attr_write);

ssize_t debugfs_attr_write_signed(struct file *file, const char __user *buf,
			 size_t len, loff_t *ppos)
{
	return debugfs_attr_write_xsigned(file, buf, len, ppos, true);
}
EXPORT_SYMBOL_GPL(debugfs_attr_write_signed);

static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode,
					struct dentry *parent, void *value,
					const struct file_operations *fops,
					const struct file_operations *fops_ro,
					const struct file_operations *fops_wo)
{
	/* if there are no write bits set, make read only */
	if (!(mode & S_IWUGO))
		return debugfs_create_file_unsafe(name, mode, parent, value,
						fops_ro);
	/* if there are no read bits set, make write only */
	if (!(mode & S_IRUGO))
		return debugfs_create_file_unsafe(name, mode, parent, value,
						fops_wo);

	return debugfs_create_file_unsafe(name, mode, parent, value, fops);
}

static int debugfs_u8_set(void *data, u64 val)
{
	*(u8 *)data = val;
	return 0;
}
static int debugfs_u8_get(void *data, u64 *val)
{
	*val = *(u8 *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");

/**
 * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_u8(const char *name, umode_t mode, struct dentry *parent,
		       u8 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u8,
				   &fops_u8_ro, &fops_u8_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_u8);

static int debugfs_u16_set(void *data, u64 val)
{
	*(u16 *)data = val;
	return 0;
}
static int debugfs_u16_get(void *data, u64 *val)
{
	*val = *(u16 *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");

/**
 * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_u16(const char *name, umode_t mode, struct dentry *parent,
			u16 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u16,
				   &fops_u16_ro, &fops_u16_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_u16);

static int debugfs_u32_set(void *data, u64 val)
{
	*(u32 *)data = val;
	return 0;
}
static int debugfs_u32_get(void *data, u64 *val)
{
	*val = *(u32 *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");

/**
 * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_u32(const char *name, umode_t mode, struct dentry *parent,
			u32 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u32,
				   &fops_u32_ro, &fops_u32_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32);

static int debugfs_u64_set(void *data, u64 val)
{
	*(u64 *)data = val;
	return 0;
}

static int debugfs_u64_get(void *data, u64 *val)
{
	*val = *(u64 *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");

/**
 * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_u64(const char *name, umode_t mode, struct dentry *parent,
			u64 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u64,
				   &fops_u64_ro, &fops_u64_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_u64);

static int debugfs_ulong_set(void *data, u64 val)
{
	*(unsigned long *)data = val;
	return 0;
}

static int debugfs_ulong_get(void *data, u64 *val)
{
	*val = *(unsigned long *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong, debugfs_ulong_get, debugfs_ulong_set,
			"%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_ro, debugfs_ulong_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n");

/**
 * debugfs_create_ulong - create a debugfs file that is used to read and write
 * an unsigned long value.
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_ulong(const char *name, umode_t mode, struct dentry *parent,
			  unsigned long *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_ulong,
				   &fops_ulong_ro, &fops_ulong_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_ulong);

DEFINE_DEBUGFS_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n");

DEFINE_DEBUGFS_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set,
			"0x%04llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n");

DEFINE_DEBUGFS_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set,
			"0x%08llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n");

DEFINE_DEBUGFS_ATTRIBUTE(fops_x64, debugfs_u64_get, debugfs_u64_set,
			"0x%016llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x64_ro, debugfs_u64_get, NULL, "0x%016llx\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_x64_wo, NULL, debugfs_u64_set, "0x%016llx\n");

/*
 * debugfs_create_x{8,16,32,64} - create a debugfs file that is used to read and write an unsigned {8,16,32,64}-bit value
 *
 * These functions are exactly the same as the above functions (but use a hex
 * output for the decimal challenged). For details look at the above unsigned
 * decimal functions.
 */

/**
 * debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_x8(const char *name, umode_t mode, struct dentry *parent,
		       u8 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x8,
				   &fops_x8_ro, &fops_x8_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_x8);

/**
 * debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_x16(const char *name, umode_t mode, struct dentry *parent,
			u16 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x16,
				   &fops_x16_ro, &fops_x16_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_x16);

/**
 * debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_x32(const char *name, umode_t mode, struct dentry *parent,
			u32 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x32,
				   &fops_x32_ro, &fops_x32_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_x32);

/**
 * debugfs_create_x64 - create a debugfs file that is used to read and write an unsigned 64-bit value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_x64(const char *name, umode_t mode, struct dentry *parent,
			u64 *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x64,
				   &fops_x64_ro, &fops_x64_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_x64);


static int debugfs_size_t_set(void *data, u64 val)
{
	*(size_t *)data = val;
	return 0;
}
static int debugfs_size_t_get(void *data, u64 *val)
{
	*val = *(size_t *)data;
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set,
			"%llu\n"); /* %llu and %zu are more or less the same */
DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t_ro, debugfs_size_t_get, NULL, "%llu\n");
DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t_wo, NULL, debugfs_size_t_set, "%llu\n");

/**
 * debugfs_create_size_t - create a debugfs file that is used to read and write an size_t value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_size_t(const char *name, umode_t mode,
			   struct dentry *parent, size_t *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_size_t,
				   &fops_size_t_ro, &fops_size_t_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_size_t);

static int debugfs_atomic_t_set(void *data, u64 val)
{
	atomic_set((atomic_t *)data, val);
	return 0;
}
static int debugfs_atomic_t_get(void *data, u64 *val)
{
	*val = atomic_read((atomic_t *)data);
	return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t, debugfs_atomic_t_get,
			debugfs_atomic_t_set, "%lld\n");
DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_ro, debugfs_atomic_t_get, NULL,
			"%lld\n");
DEFINE_DEBUGFS_ATTRIBUTE_SIGNED(fops_atomic_t_wo, NULL, debugfs_atomic_t_set,
			"%lld\n");

/**
 * debugfs_create_atomic_t - create a debugfs file that is used to read and
 * write an atomic_t value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 */
void debugfs_create_atomic_t(const char *name, umode_t mode,
			     struct dentry *parent, atomic_t *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_atomic_t,
				   &fops_atomic_t_ro, &fops_atomic_t_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_atomic_t);

ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf,
			       size_t count, loff_t *ppos)
{
	char buf[2];
	bool val;
	int r;
	struct dentry *dentry = F_DENTRY(file);

	r = debugfs_file_get(dentry);
	if (unlikely(r))
		return r;
	val = *(bool *)file->private_data;
	debugfs_file_put(dentry);

	if (val)
		buf[0] = 'Y';
	else
		buf[0] = 'N';
	buf[1] = '\n';
	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}
EXPORT_SYMBOL_GPL(debugfs_read_file_bool);

ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf,
				size_t count, loff_t *ppos)
{
	bool bv;
	int r;
	bool *val = file->private_data;
	struct dentry *dentry = F_DENTRY(file);

	r = kstrtobool_from_user(user_buf, count, &bv);
	if (!r) {
		r = debugfs_file_get(dentry);
		if (unlikely(r))
			return r;
		*val = bv;
		debugfs_file_put(dentry);
	}

	return count;
}
EXPORT_SYMBOL_GPL(debugfs_write_file_bool);

static const struct file_operations fops_bool = {
	.read =		debugfs_read_file_bool,
	.write =	debugfs_write_file_bool,
	.open =		simple_open,
	.llseek =	default_llseek,
};

static const struct file_operations fops_bool_ro = {
	.read =		debugfs_read_file_bool,
	.open =		simple_open,
	.llseek =	default_llseek,
};

static const struct file_operations fops_bool_wo = {
	.write =	debugfs_write_file_bool,
	.open =		simple_open,
	.llseek =	default_llseek,
};

/**
 * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent,
			 bool *value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool,
				   &fops_bool_ro, &fops_bool_wo);
}
EXPORT_SYMBOL_GPL(debugfs_create_bool);

ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf,
			      size_t count, loff_t *ppos)
{
	struct dentry *dentry = F_DENTRY(file);
	char *str, *copy = NULL;
	int copy_len, len;
	ssize_t ret;

	ret = debugfs_file_get(dentry);
	if (unlikely(ret))
		return ret;

	str = *(char **)file->private_data;
	len = strlen(str) + 1;
	copy = kmalloc(len, GFP_KERNEL);
	if (!copy) {
		debugfs_file_put(dentry);
		return -ENOMEM;
	}

	copy_len = strscpy(copy, str, len);
	debugfs_file_put(dentry);
	if (copy_len < 0) {
		kfree(copy);
		return copy_len;
	}

	copy[copy_len] = '\n';

	ret = simple_read_from_buffer(user_buf, count, ppos, copy, len);
	kfree(copy);

	return ret;
}
EXPORT_SYMBOL_GPL(debugfs_create_str);

static ssize_t debugfs_write_file_str(struct file *file, const char __user *user_buf,
				      size_t count, loff_t *ppos)
{
	struct dentry *dentry = F_DENTRY(file);
	char *old, *new = NULL;
	int pos = *ppos;
	int r;

	r = debugfs_file_get(dentry);
	if (unlikely(r))
		return r;

	old = *(char **)file->private_data;

	/* only allow strict concatenation */
	r = -EINVAL;
	if (pos && pos != strlen(old))
		goto error;

	r = -E2BIG;
	if (pos + count + 1 > PAGE_SIZE)
		goto error;

	r = -ENOMEM;
	new = kmalloc(pos + count + 1, GFP_KERNEL);
	if (!new)
		goto error;

	if (pos)
		memcpy(new, old, pos);

	r = -EFAULT;
	if (copy_from_user(new + pos, user_buf, count))
		goto error;

	new[pos + count] = '\0';
	strim(new);

	rcu_assign_pointer(*(char __rcu **)file->private_data, new);
	synchronize_rcu();
	kfree(old);

	debugfs_file_put(dentry);
	return count;

error:
	kfree(new);
	debugfs_file_put(dentry);
	return r;
}

static const struct file_operations fops_str = {
	.read =		debugfs_read_file_str,
	.write =	debugfs_write_file_str,
	.open =		simple_open,
	.llseek =	default_llseek,
};

static const struct file_operations fops_str_ro = {
	.read =		debugfs_read_file_str,
	.open =		simple_open,
	.llseek =	default_llseek,
};

static const struct file_operations fops_str_wo = {
	.write =	debugfs_write_file_str,
	.open =		simple_open,
	.llseek =	default_llseek,
};

/**
 * debugfs_create_str - create a debugfs file that is used to read and write a string value
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @value: a pointer to the variable that the file should read to and write
 *         from.
 *
 * This function creates a file in debugfs with the given name that
 * contains the value of the variable @value.  If the @mode variable is so
 * set, it can be read from, and written to.
 */
void debugfs_create_str(const char *name, umode_t mode,
			struct dentry *parent, char **value)
{
	debugfs_create_mode_unsafe(name, mode, parent, value, &fops_str,
				   &fops_str_ro, &fops_str_wo);
}

static ssize_t read_file_blob(struct file *file, char __user *user_buf,
			      size_t count, loff_t *ppos)
{
	struct debugfs_blob_wrapper *blob = file->private_data;
	struct dentry *dentry = F_DENTRY(file);
	ssize_t r;

	r = debugfs_file_get(dentry);
	if (unlikely(r))
		return r;
	r = simple_read_from_buffer(user_buf, count, ppos, blob->data,
				blob->size);
	debugfs_file_put(dentry);
	return r;
}

static ssize_t write_file_blob(struct file *file, const char __user *user_buf,
			       size_t count, loff_t *ppos)
{
	struct debugfs_blob_wrapper *blob = file->private_data;
	struct dentry *dentry = F_DENTRY(file);
	ssize_t r;

	r = debugfs_file_get(dentry);
	if (unlikely(r))
		return r;
	r = simple_write_to_buffer(blob->data, blob->size, ppos, user_buf,
				   count);

	debugfs_file_put(dentry);
	return r;
}

static const struct file_operations fops_blob = {
	.read =		read_file_blob,
	.write =	write_file_blob,
	.open =		simple_open,
	.llseek =	default_llseek,
};

/**
 * debugfs_create_blob - create a debugfs file that is used to read and write
 * a binary blob
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 *        to the blob data and the size of the data.
 *
 * This function creates a file in debugfs with the given name that exports
 * @blob->data as a binary blob. If the @mode variable is so set it can be
 * read from and written to.
 *
 * This function will return a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the debugfs_remove() function when the file is
 * to be removed (no automatic cleanup happens if your module is unloaded,
 * you are responsible here.)  If an error occurs, ERR_PTR(-ERROR) will be
 * returned.
 *
 * If debugfs is not enabled in the kernel, the value ERR_PTR(-ENODEV) will
 * be returned.
 */
struct dentry *debugfs_create_blob(const char *name, umode_t mode,
				   struct dentry *parent,
				   struct debugfs_blob_wrapper *blob)
{
	return debugfs_create_file_unsafe(name, mode & 0644, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);

static size_t u32_format_array(char *buf, size_t bufsize,
			       u32 *array, int array_size)
{
	size_t ret = 0;

	while (--array_size >= 0) {
		size_t len;
		char term = array_size ? ' ' : '\n';

		len = snprintf(buf, bufsize, "%u%c", *array++, term);
		ret += len;

		buf += len;
		bufsize -= len;
	}
	return ret;
}

static int u32_array_open(struct inode *inode, struct file *file)
{
	struct debugfs_u32_array *data = inode->i_private;
	int size, elements = data->n_elements;
	char *buf;

	/*
	 * Max size:
	 *  - 10 digits + ' '/'\n' = 11 bytes per number
	 *  - terminating NUL character
	 */
	size = elements*11;
	buf = kmalloc(size+1, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
	buf[size] = 0;

	file->private_data = buf;
	u32_format_array(buf, size, data->array, data->n_elements);

	return nonseekable_open(inode, file);
}

static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
			      loff_t *ppos)
{
	size_t size = strlen(file->private_data);

	return simple_read_from_buffer(buf, len, ppos,
					file->private_data, size);
}

static int u32_array_release(struct inode *inode, struct file *file)
{
	kfree(file->private_data);

	return 0;
}

static const struct file_operations u32_array_fops = {
	.owner	 = THIS_MODULE,
	.open	 = u32_array_open,
	.release = u32_array_release,
	.read	 = u32_array_read,
	.llseek  = no_llseek,
};

/**
 * debugfs_create_u32_array - create a debugfs file that is used to read u32
 * array.
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have.
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @array: wrapper struct containing data pointer and size of the array.
 *
 * This function creates a file in debugfs with the given name that exports
 * @array as data. If the @mode variable is so set it can be read from.
 * Writing is not supported. Seek within the file is also not supported.
 * Once array is created its size can not be changed.
 */
void debugfs_create_u32_array(const char *name, umode_t mode,
			      struct dentry *parent,
			      struct debugfs_u32_array *array)
{
	debugfs_create_file_unsafe(name, mode, parent, array, &u32_array_fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32_array);

#ifdef CONFIG_HAS_IOMEM

/*
 * The regset32 stuff is used to print 32-bit registers using the
 * seq_file utilities. We offer printing a register set in an already-opened
 * sequential file or create a debugfs file that only prints a regset32.
 */

/**
 * debugfs_print_regs32 - use seq_print to describe a set of registers
 * @s: the seq_file structure being used to generate output
 * @regs: an array if struct debugfs_reg32 structures
 * @nregs: the length of the above array
 * @base: the base address to be used in reading the registers
 * @prefix: a string to be prefixed to every output line
 *
 * This function outputs a text block describing the current values of
 * some 32-bit hardware registers. It is meant to be used within debugfs
 * files based on seq_file that need to show registers, intermixed with other
 * information. The prefix argument may be used to specify a leading string,
 * because some peripherals have several blocks of identical registers,
 * for example configuration of dma channels
 */
void debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
			  int nregs, void __iomem *base, char *prefix)
{
	int i;

	for (i = 0; i < nregs; i++, regs++) {
		if (prefix)
			seq_printf(s, "%s", prefix);
		seq_printf(s, "%s = 0x%08x\n", regs->name,
			   readl(base + regs->offset));
		if (seq_has_overflowed(s))
			break;
	}
}
EXPORT_SYMBOL_GPL(debugfs_print_regs32);

static int debugfs_regset32_show(struct seq_file *s, void *data)
{
	struct debugfs_regset32 *regset = s->private;

	if (regset->dev)
		pm_runtime_get_sync(regset->dev);

	debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");

	if (regset->dev)
		pm_runtime_put(regset->dev);

	return 0;
}

DEFINE_SHOW_ATTRIBUTE(debugfs_regset32);

/**
 * debugfs_create_regset32 - create a debugfs file that returns register values
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the debugfs filesystem.
 * @regset: a pointer to a struct debugfs_regset32, which contains a pointer
 *          to an array of register definitions, the array size and the base
 *          address where the register bank is to be found.
 *
 * This function creates a file in debugfs with the given name that reports
 * the names and values of a set of 32-bit registers. If the @mode variable
 * is so set it can be read from. Writing is not supported.
 */
void debugfs_create_regset32(const char *name, umode_t mode,
			     struct dentry *parent,
			     struct debugfs_regset32 *regset)
{
	debugfs_create_file(name, mode, parent, regset, &debugfs_regset32_fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_regset32);

#endif /* CONFIG_HAS_IOMEM */

struct debugfs_devm_entry {
	int (*read)(struct seq_file *seq, void *data);
	struct device *dev;
};

static int debugfs_devm_entry_open(struct inode *inode, struct file *f)
{
	struct debugfs_devm_entry *entry = inode->i_private;

	return single_open(f, entry->read, entry->dev);
}

static const struct file_operations debugfs_devm_entry_ops = {
	.owner = THIS_MODULE,
	.open = debugfs_devm_entry_open,
	.release = single_release,
	.read = seq_read,
	.llseek = seq_lseek
};

/**
 * debugfs_create_devm_seqfile - create a debugfs file that is bound to device.
 *
 * @dev: device related to this debugfs file.
 * @name: name of the debugfs file.
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *	directory dentry if set.  If this parameter is %NULL, then the
 *	file will be created in the root of the debugfs filesystem.
 * @read_fn: function pointer called to print the seq_file content.
 */
void debugfs_create_devm_seqfile(struct device *dev, const char *name,
				 struct dentry *parent,
				 int (*read_fn)(struct seq_file *s, void *data))
{
	struct debugfs_devm_entry *entry;

	if (IS_ERR(parent))
		return;

	entry = devm_kzalloc(dev, sizeof(*entry), GFP_KERNEL);
	if (!entry)
		return;

	entry->read = read_fn;
	entry->dev = dev;

	debugfs_create_file(name, S_IRUGO, parent, entry,
			    &debugfs_devm_entry_ops);
}
EXPORT_SYMBOL_GPL(debugfs_create_devm_seqfile);