summaryrefslogtreecommitdiff
path: root/drivers/hwtracing/intel_th/msu.c
blob: 634f58042c77f36b7e512a84510e2ac8947eab0e (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
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
// SPDX-License-Identifier: GPL-2.0
/*
 * Intel(R) Trace Hub Memory Storage Unit
 *
 * Copyright (C) 2014-2015 Intel Corporation.
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/sizes.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>

#ifdef CONFIG_X86
#include <asm/set_memory.h>
#endif

#include "intel_th.h"
#include "msu.h"

#define msc_dev(x) (&(x)->thdev->dev)

/**
 * struct msc_block - multiblock mode block descriptor
 * @bdesc:	pointer to hardware descriptor (beginning of the block)
 * @addr:	physical address of the block
 */
struct msc_block {
	struct msc_block_desc	*bdesc;
	dma_addr_t		addr;
};

/**
 * struct msc_window - multiblock mode window descriptor
 * @entry:	window list linkage (msc::win_list)
 * @pgoff:	page offset into the buffer that this window starts at
 * @nr_blocks:	number of blocks (pages) in this window
 * @block:	array of block descriptors
 */
struct msc_window {
	struct list_head	entry;
	unsigned long		pgoff;
	unsigned int		nr_blocks;
	struct msc		*msc;
	struct msc_block	block[0];
};

/**
 * struct msc_iter - iterator for msc buffer
 * @entry:		msc::iter_list linkage
 * @msc:		pointer to the MSC device
 * @start_win:		oldest window
 * @win:		current window
 * @offset:		current logical offset into the buffer
 * @start_block:	oldest block in the window
 * @block:		block number in the window
 * @block_off:		offset into current block
 * @wrap_count:		block wrapping handling
 * @eof:		end of buffer reached
 */
struct msc_iter {
	struct list_head	entry;
	struct msc		*msc;
	struct msc_window	*start_win;
	struct msc_window	*win;
	unsigned long		offset;
	int			start_block;
	int			block;
	unsigned int		block_off;
	unsigned int		wrap_count;
	unsigned int		eof;
};

/**
 * struct msc - MSC device representation
 * @reg_base:		register window base address
 * @thdev:		intel_th_device pointer
 * @win_list:		list of windows in multiblock mode
 * @nr_pages:		total number of pages allocated for this buffer
 * @single_sz:		amount of data in single mode
 * @single_wrap:	single mode wrap occurred
 * @base:		buffer's base pointer
 * @base_addr:		buffer's base address
 * @user_count:		number of users of the buffer
 * @mmap_count:		number of mappings
 * @buf_mutex:		mutex to serialize access to buffer-related bits

 * @enabled:		MSC is enabled
 * @wrap:		wrapping is enabled
 * @mode:		MSC operating mode
 * @burst_len:		write burst length
 * @index:		number of this MSC in the MSU
 */
struct msc {
	void __iomem		*reg_base;
	struct intel_th_device	*thdev;

	struct list_head	win_list;
	unsigned long		nr_pages;
	unsigned long		single_sz;
	unsigned int		single_wrap : 1;
	void			*base;
	dma_addr_t		base_addr;

	/* <0: no buffer, 0: no users, >0: active users */
	atomic_t		user_count;

	atomic_t		mmap_count;
	struct mutex		buf_mutex;

	struct list_head	iter_list;

	/* config */
	unsigned int		enabled : 1,
				wrap	: 1;
	unsigned int		mode;
	unsigned int		burst_len;
	unsigned int		index;
};

static inline bool msc_block_is_empty(struct msc_block_desc *bdesc)
{
	/* header hasn't been written */
	if (!bdesc->valid_dw)
		return true;

	/* valid_dw includes the header */
	if (!msc_data_sz(bdesc))
		return true;

	return false;
}

/**
 * msc_oldest_window() - locate the window with oldest data
 * @msc:	MSC device
 *
 * This should only be used in multiblock mode. Caller should hold the
 * msc::user_count reference.
 *
 * Return:	the oldest window with valid data
 */
static struct msc_window *msc_oldest_window(struct msc *msc)
{
	struct msc_window *win;
	u32 reg = ioread32(msc->reg_base + REG_MSU_MSC0NWSA);
	unsigned long win_addr = (unsigned long)reg << PAGE_SHIFT;
	unsigned int found = 0;

	if (list_empty(&msc->win_list))
		return NULL;

	/*
	 * we might need a radix tree for this, depending on how
	 * many windows a typical user would allocate; ideally it's
	 * something like 2, in which case we're good
	 */
	list_for_each_entry(win, &msc->win_list, entry) {
		if (win->block[0].addr == win_addr)
			found++;

		/* skip the empty ones */
		if (msc_block_is_empty(win->block[0].bdesc))
			continue;

		if (found)
			return win;
	}

	return list_entry(msc->win_list.next, struct msc_window, entry);
}

/**
 * msc_win_oldest_block() - locate the oldest block in a given window
 * @win:	window to look at
 *
 * Return:	index of the block with the oldest data
 */
static unsigned int msc_win_oldest_block(struct msc_window *win)
{
	unsigned int blk;
	struct msc_block_desc *bdesc = win->block[0].bdesc;

	/* without wrapping, first block is the oldest */
	if (!msc_block_wrapped(bdesc))
		return 0;

	/*
	 * with wrapping, last written block contains both the newest and the
	 * oldest data for this window.
	 */
	for (blk = 0; blk < win->nr_blocks; blk++) {
		bdesc = win->block[blk].bdesc;

		if (msc_block_last_written(bdesc))
			return blk;
	}

	return 0;
}

/**
 * msc_is_last_win() - check if a window is the last one for a given MSC
 * @win:	window
 * Return:	true if @win is the last window in MSC's multiblock buffer
 */
static inline bool msc_is_last_win(struct msc_window *win)
{
	return win->entry.next == &win->msc->win_list;
}

/**
 * msc_next_window() - return next window in the multiblock buffer
 * @win:	current window
 *
 * Return:	window following the current one
 */
static struct msc_window *msc_next_window(struct msc_window *win)
{
	if (msc_is_last_win(win))
		return list_entry(win->msc->win_list.next, struct msc_window,
				  entry);

	return list_entry(win->entry.next, struct msc_window, entry);
}

static struct msc_block_desc *msc_iter_bdesc(struct msc_iter *iter)
{
	return iter->win->block[iter->block].bdesc;
}

static void msc_iter_init(struct msc_iter *iter)
{
	memset(iter, 0, sizeof(*iter));
	iter->start_block = -1;
	iter->block = -1;
}

static struct msc_iter *msc_iter_install(struct msc *msc)
{
	struct msc_iter *iter;

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

	mutex_lock(&msc->buf_mutex);

	/*
	 * Reading and tracing are mutually exclusive; if msc is
	 * enabled, open() will fail; otherwise existing readers
	 * will prevent enabling the msc and the rest of fops don't
	 * need to worry about it.
	 */
	if (msc->enabled) {
		kfree(iter);
		iter = ERR_PTR(-EBUSY);
		goto unlock;
	}

	msc_iter_init(iter);
	iter->msc = msc;

	list_add_tail(&iter->entry, &msc->iter_list);
unlock:
	mutex_unlock(&msc->buf_mutex);

	return iter;
}

static void msc_iter_remove(struct msc_iter *iter, struct msc *msc)
{
	mutex_lock(&msc->buf_mutex);
	list_del(&iter->entry);
	mutex_unlock(&msc->buf_mutex);

	kfree(iter);
}

static void msc_iter_block_start(struct msc_iter *iter)
{
	if (iter->start_block != -1)
		return;

	iter->start_block = msc_win_oldest_block(iter->win);
	iter->block = iter->start_block;
	iter->wrap_count = 0;

	/*
	 * start with the block with oldest data; if data has wrapped
	 * in this window, it should be in this block
	 */
	if (msc_block_wrapped(msc_iter_bdesc(iter)))
		iter->wrap_count = 2;

}

static int msc_iter_win_start(struct msc_iter *iter, struct msc *msc)
{
	/* already started, nothing to do */
	if (iter->start_win)
		return 0;

	iter->start_win = msc_oldest_window(msc);
	if (!iter->start_win)
		return -EINVAL;

	iter->win = iter->start_win;
	iter->start_block = -1;

	msc_iter_block_start(iter);

	return 0;
}

static int msc_iter_win_advance(struct msc_iter *iter)
{
	iter->win = msc_next_window(iter->win);
	iter->start_block = -1;

	if (iter->win == iter->start_win) {
		iter->eof++;
		return 1;
	}

	msc_iter_block_start(iter);

	return 0;
}

static int msc_iter_block_advance(struct msc_iter *iter)
{
	iter->block_off = 0;

	/* wrapping */
	if (iter->wrap_count && iter->block == iter->start_block) {
		iter->wrap_count--;
		if (!iter->wrap_count)
			/* copied newest data from the wrapped block */
			return msc_iter_win_advance(iter);
	}

	/* no wrapping, check for last written block */
	if (!iter->wrap_count && msc_block_last_written(msc_iter_bdesc(iter)))
		/* copied newest data for the window */
		return msc_iter_win_advance(iter);

	/* block advance */
	if (++iter->block == iter->win->nr_blocks)
		iter->block = 0;

	/* no wrapping, sanity check in case there is no last written block */
	if (!iter->wrap_count && iter->block == iter->start_block)
		return msc_iter_win_advance(iter);

	return 0;
}

/**
 * msc_buffer_iterate() - go through multiblock buffer's data
 * @iter:	iterator structure
 * @size:	amount of data to scan
 * @data:	callback's private data
 * @fn:		iterator callback
 *
 * This will start at the window which will be written to next (containing
 * the oldest data) and work its way to the current window, calling @fn
 * for each chunk of data as it goes.
 *
 * Caller should have msc::user_count reference to make sure the buffer
 * doesn't disappear from under us.
 *
 * Return:	amount of data actually scanned.
 */
static ssize_t
msc_buffer_iterate(struct msc_iter *iter, size_t size, void *data,
		   unsigned long (*fn)(void *, void *, size_t))
{
	struct msc *msc = iter->msc;
	size_t len = size;
	unsigned int advance;

	if (iter->eof)
		return 0;

	/* start with the oldest window */
	if (msc_iter_win_start(iter, msc))
		return 0;

	do {
		unsigned long data_bytes = msc_data_sz(msc_iter_bdesc(iter));
		void *src = (void *)msc_iter_bdesc(iter) + MSC_BDESC;
		size_t tocopy = data_bytes, copied = 0;
		size_t remaining = 0;

		advance = 1;

		/*
		 * If block wrapping happened, we need to visit the last block
		 * twice, because it contains both the oldest and the newest
		 * data in this window.
		 *
		 * First time (wrap_count==2), in the very beginning, to collect
		 * the oldest data, which is in the range
		 * (data_bytes..DATA_IN_PAGE).
		 *
		 * Second time (wrap_count==1), it's just like any other block,
		 * containing data in the range of [MSC_BDESC..data_bytes].
		 */
		if (iter->block == iter->start_block && iter->wrap_count == 2) {
			tocopy = DATA_IN_PAGE - data_bytes;
			src += data_bytes;
		}

		if (!tocopy)
			goto next_block;

		tocopy -= iter->block_off;
		src += iter->block_off;

		if (len < tocopy) {
			tocopy = len;
			advance = 0;
		}

		remaining = fn(data, src, tocopy);

		if (remaining)
			advance = 0;

		copied = tocopy - remaining;
		len -= copied;
		iter->block_off += copied;
		iter->offset += copied;

		if (!advance)
			break;

next_block:
		if (msc_iter_block_advance(iter))
			break;

	} while (len);

	return size - len;
}

/**
 * msc_buffer_clear_hw_header() - clear hw header for multiblock
 * @msc:	MSC device
 */
static void msc_buffer_clear_hw_header(struct msc *msc)
{
	struct msc_window *win;

	list_for_each_entry(win, &msc->win_list, entry) {
		unsigned int blk;
		size_t hw_sz = sizeof(struct msc_block_desc) -
			offsetof(struct msc_block_desc, hw_tag);

		for (blk = 0; blk < win->nr_blocks; blk++) {
			struct msc_block_desc *bdesc = win->block[blk].bdesc;

			memset(&bdesc->hw_tag, 0, hw_sz);
		}
	}
}

/**
 * msc_configure() - set up MSC hardware
 * @msc:	the MSC device to configure
 *
 * Program storage mode, wrapping, burst length and trace buffer address
 * into a given MSC. Then, enable tracing and set msc::enabled.
 * The latter is serialized on msc::buf_mutex, so make sure to hold it.
 */
static int msc_configure(struct msc *msc)
{
	u32 reg;

	lockdep_assert_held(&msc->buf_mutex);

	if (msc->mode > MSC_MODE_MULTI)
		return -ENOTSUPP;

	if (msc->mode == MSC_MODE_MULTI)
		msc_buffer_clear_hw_header(msc);

	reg = msc->base_addr >> PAGE_SHIFT;
	iowrite32(reg, msc->reg_base + REG_MSU_MSC0BAR);

	if (msc->mode == MSC_MODE_SINGLE) {
		reg = msc->nr_pages;
		iowrite32(reg, msc->reg_base + REG_MSU_MSC0SIZE);
	}

	reg = ioread32(msc->reg_base + REG_MSU_MSC0CTL);
	reg &= ~(MSC_MODE | MSC_WRAPEN | MSC_EN | MSC_RD_HDR_OVRD);

	reg |= MSC_EN;
	reg |= msc->mode << __ffs(MSC_MODE);
	reg |= msc->burst_len << __ffs(MSC_LEN);

	if (msc->wrap)
		reg |= MSC_WRAPEN;

	iowrite32(reg, msc->reg_base + REG_MSU_MSC0CTL);

	msc->thdev->output.multiblock = msc->mode == MSC_MODE_MULTI;
	intel_th_trace_enable(msc->thdev);
	msc->enabled = 1;


	return 0;
}

/**
 * msc_disable() - disable MSC hardware
 * @msc:	MSC device to disable
 *
 * If @msc is enabled, disable tracing on the switch and then disable MSC
 * storage. Caller must hold msc::buf_mutex.
 */
static void msc_disable(struct msc *msc)
{
	unsigned long count;
	u32 reg;

	lockdep_assert_held(&msc->buf_mutex);

	intel_th_trace_disable(msc->thdev);

	for (reg = 0, count = MSC_PLE_WAITLOOP_DEPTH;
	     count && !(reg & MSCSTS_PLE); count--) {
		reg = ioread32(msc->reg_base + REG_MSU_MSC0STS);
		cpu_relax();
	}

	if (!count)
		dev_dbg(msc_dev(msc), "timeout waiting for MSC0 PLE\n");

	if (msc->mode == MSC_MODE_SINGLE) {
		msc->single_wrap = !!(reg & MSCSTS_WRAPSTAT);

		reg = ioread32(msc->reg_base + REG_MSU_MSC0MWP);
		msc->single_sz = reg & ((msc->nr_pages << PAGE_SHIFT) - 1);
		dev_dbg(msc_dev(msc), "MSCnMWP: %08x/%08lx, wrap: %d\n",
			reg, msc->single_sz, msc->single_wrap);
	}

	reg = ioread32(msc->reg_base + REG_MSU_MSC0CTL);
	reg &= ~MSC_EN;
	iowrite32(reg, msc->reg_base + REG_MSU_MSC0CTL);
	msc->enabled = 0;

	iowrite32(0, msc->reg_base + REG_MSU_MSC0BAR);
	iowrite32(0, msc->reg_base + REG_MSU_MSC0SIZE);

	dev_dbg(msc_dev(msc), "MSCnNWSA: %08x\n",
		ioread32(msc->reg_base + REG_MSU_MSC0NWSA));

	reg = ioread32(msc->reg_base + REG_MSU_MSC0STS);
	dev_dbg(msc_dev(msc), "MSCnSTS: %08x\n", reg);
}

static int intel_th_msc_activate(struct intel_th_device *thdev)
{
	struct msc *msc = dev_get_drvdata(&thdev->dev);
	int ret = -EBUSY;

	if (!atomic_inc_unless_negative(&msc->user_count))
		return -ENODEV;

	mutex_lock(&msc->buf_mutex);

	/* if there are readers, refuse */
	if (list_empty(&msc->iter_list))
		ret = msc_configure(msc);

	mutex_unlock(&msc->buf_mutex);

	if (ret)
		atomic_dec(&msc->user_count);

	return ret;
}

static void intel_th_msc_deactivate(struct intel_th_device *thdev)
{
	struct msc *msc = dev_get_drvdata(&thdev->dev);

	mutex_lock(&msc->buf_mutex);
	if (msc->enabled) {
		msc_disable(msc);
		atomic_dec(&msc->user_count);
	}
	mutex_unlock(&msc->buf_mutex);
}

/**
 * msc_buffer_contig_alloc() - allocate a contiguous buffer for SINGLE mode
 * @msc:	MSC device
 * @size:	allocation size in bytes
 *
 * This modifies msc::base, which requires msc::buf_mutex to serialize, so the
 * caller is expected to hold it.
 *
 * Return:	0 on success, -errno otherwise.
 */
static int msc_buffer_contig_alloc(struct msc *msc, unsigned long size)
{
	unsigned int order = get_order(size);
	struct page *page;

	if (!size)
		return 0;

	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
	if (!page)
		return -ENOMEM;

	split_page(page, order);
	msc->nr_pages = size >> PAGE_SHIFT;
	msc->base = page_address(page);
	msc->base_addr = page_to_phys(page);

	return 0;
}

/**
 * msc_buffer_contig_free() - free a contiguous buffer
 * @msc:	MSC configured in SINGLE mode
 */
static void msc_buffer_contig_free(struct msc *msc)
{
	unsigned long off;

	for (off = 0; off < msc->nr_pages << PAGE_SHIFT; off += PAGE_SIZE) {
		struct page *page = virt_to_page(msc->base + off);

		page->mapping = NULL;
		__free_page(page);
	}

	msc->nr_pages = 0;
}

/**
 * msc_buffer_contig_get_page() - find a page at a given offset
 * @msc:	MSC configured in SINGLE mode
 * @pgoff:	page offset
 *
 * Return:	page, if @pgoff is within the range, NULL otherwise.
 */
static struct page *msc_buffer_contig_get_page(struct msc *msc,
					       unsigned long pgoff)
{
	if (pgoff >= msc->nr_pages)
		return NULL;

	return virt_to_page(msc->base + (pgoff << PAGE_SHIFT));
}

/**
 * msc_buffer_win_alloc() - alloc a window for a multiblock mode
 * @msc:	MSC device
 * @nr_blocks:	number of pages in this window
 *
 * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
 * to serialize, so the caller is expected to hold it.
 *
 * Return:	0 on success, -errno otherwise.
 */
static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks)
{
	struct msc_window *win;
	unsigned long size = PAGE_SIZE;
	int i, ret = -ENOMEM;

	if (!nr_blocks)
		return 0;

	win = kzalloc(offsetof(struct msc_window, block[nr_blocks]),
		      GFP_KERNEL);
	if (!win)
		return -ENOMEM;

	if (!list_empty(&msc->win_list)) {
		struct msc_window *prev = list_entry(msc->win_list.prev,
						     struct msc_window, entry);

		win->pgoff = prev->pgoff + prev->nr_blocks;
	}

	for (i = 0; i < nr_blocks; i++) {
		win->block[i].bdesc =
			dma_alloc_coherent(msc_dev(msc)->parent->parent, size,
					   &win->block[i].addr, GFP_KERNEL);

		if (!win->block[i].bdesc)
			goto err_nomem;

#ifdef CONFIG_X86
		/* Set the page as uncached */
		set_memory_uc((unsigned long)win->block[i].bdesc, 1);
#endif
	}

	win->msc = msc;
	win->nr_blocks = nr_blocks;

	if (list_empty(&msc->win_list)) {
		msc->base = win->block[0].bdesc;
		msc->base_addr = win->block[0].addr;
	}

	list_add_tail(&win->entry, &msc->win_list);
	msc->nr_pages += nr_blocks;

	return 0;

err_nomem:
	for (i--; i >= 0; i--) {
#ifdef CONFIG_X86
		/* Reset the page to write-back before releasing */
		set_memory_wb((unsigned long)win->block[i].bdesc, 1);
#endif
		dma_free_coherent(msc_dev(msc)->parent->parent, size,
				  win->block[i].bdesc, win->block[i].addr);
	}
	kfree(win);

	return ret;
}

/**
 * msc_buffer_win_free() - free a window from MSC's window list
 * @msc:	MSC device
 * @win:	window to free
 *
 * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
 * to serialize, so the caller is expected to hold it.
 */
static void msc_buffer_win_free(struct msc *msc, struct msc_window *win)
{
	int i;

	msc->nr_pages -= win->nr_blocks;

	list_del(&win->entry);
	if (list_empty(&msc->win_list)) {
		msc->base = NULL;
		msc->base_addr = 0;
	}

	for (i = 0; i < win->nr_blocks; i++) {
		struct page *page = virt_to_page(win->block[i].bdesc);

		page->mapping = NULL;
#ifdef CONFIG_X86
		/* Reset the page to write-back before releasing */
		set_memory_wb((unsigned long)win->block[i].bdesc, 1);
#endif
		dma_free_coherent(msc_dev(win->msc)->parent->parent, PAGE_SIZE,
				  win->block[i].bdesc, win->block[i].addr);
	}

	kfree(win);
}

/**
 * msc_buffer_relink() - set up block descriptors for multiblock mode
 * @msc:	MSC device
 *
 * This traverses msc::win_list, which requires msc::buf_mutex to serialize,
 * so the caller is expected to hold it.
 */
static void msc_buffer_relink(struct msc *msc)
{
	struct msc_window *win, *next_win;

	/* call with msc::mutex locked */
	list_for_each_entry(win, &msc->win_list, entry) {
		unsigned int blk;
		u32 sw_tag = 0;

		/*
		 * Last window's next_win should point to the first window
		 * and MSC_SW_TAG_LASTWIN should be set.
		 */
		if (msc_is_last_win(win)) {
			sw_tag |= MSC_SW_TAG_LASTWIN;
			next_win = list_entry(msc->win_list.next,
					      struct msc_window, entry);
		} else {
			next_win = list_entry(win->entry.next,
					      struct msc_window, entry);
		}

		for (blk = 0; blk < win->nr_blocks; blk++) {
			struct msc_block_desc *bdesc = win->block[blk].bdesc;

			memset(bdesc, 0, sizeof(*bdesc));

			bdesc->next_win = next_win->block[0].addr >> PAGE_SHIFT;

			/*
			 * Similarly to last window, last block should point
			 * to the first one.
			 */
			if (blk == win->nr_blocks - 1) {
				sw_tag |= MSC_SW_TAG_LASTBLK;
				bdesc->next_blk =
					win->block[0].addr >> PAGE_SHIFT;
			} else {
				bdesc->next_blk =
					win->block[blk + 1].addr >> PAGE_SHIFT;
			}

			bdesc->sw_tag = sw_tag;
			bdesc->block_sz = PAGE_SIZE / 64;
		}
	}

	/*
	 * Make the above writes globally visible before tracing is
	 * enabled to make sure hardware sees them coherently.
	 */
	wmb();
}

static void msc_buffer_multi_free(struct msc *msc)
{
	struct msc_window *win, *iter;

	list_for_each_entry_safe(win, iter, &msc->win_list, entry)
		msc_buffer_win_free(msc, win);
}

static int msc_buffer_multi_alloc(struct msc *msc, unsigned long *nr_pages,
				  unsigned int nr_wins)
{
	int ret, i;

	for (i = 0; i < nr_wins; i++) {
		ret = msc_buffer_win_alloc(msc, nr_pages[i]);
		if (ret) {
			msc_buffer_multi_free(msc);
			return ret;
		}
	}

	msc_buffer_relink(msc);

	return 0;
}

/**
 * msc_buffer_free() - free buffers for MSC
 * @msc:	MSC device
 *
 * Free MSC's storage buffers.
 *
 * This modifies msc::win_list and msc::base, which requires msc::buf_mutex to
 * serialize, so the caller is expected to hold it.
 */
static void msc_buffer_free(struct msc *msc)
{
	if (msc->mode == MSC_MODE_SINGLE)
		msc_buffer_contig_free(msc);
	else if (msc->mode == MSC_MODE_MULTI)
		msc_buffer_multi_free(msc);
}

/**
 * msc_buffer_alloc() - allocate a buffer for MSC
 * @msc:	MSC device
 * @size:	allocation size in bytes
 *
 * Allocate a storage buffer for MSC, depending on the msc::mode, it will be
 * either done via msc_buffer_contig_alloc() for SINGLE operation mode or
 * msc_buffer_win_alloc() for multiblock operation. The latter allocates one
 * window per invocation, so in multiblock mode this can be called multiple
 * times for the same MSC to allocate multiple windows.
 *
 * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
 * to serialize, so the caller is expected to hold it.
 *
 * Return:	0 on success, -errno otherwise.
 */
static int msc_buffer_alloc(struct msc *msc, unsigned long *nr_pages,
			    unsigned int nr_wins)
{
	int ret;

	/* -1: buffer not allocated */
	if (atomic_read(&msc->user_count) != -1)
		return -EBUSY;

	if (msc->mode == MSC_MODE_SINGLE) {
		if (nr_wins != 1)
			return -EINVAL;

		ret = msc_buffer_contig_alloc(msc, nr_pages[0] << PAGE_SHIFT);
	} else if (msc->mode == MSC_MODE_MULTI) {
		ret = msc_buffer_multi_alloc(msc, nr_pages, nr_wins);
	} else {
		ret = -ENOTSUPP;
	}

	if (!ret) {
		/* allocation should be visible before the counter goes to 0 */
		smp_mb__before_atomic();

		if (WARN_ON_ONCE(atomic_cmpxchg(&msc->user_count, -1, 0) != -1))
			return -EINVAL;
	}

	return ret;
}

/**
 * msc_buffer_unlocked_free_unless_used() - free a buffer unless it's in use
 * @msc:	MSC device
 *
 * This will free MSC buffer unless it is in use or there is no allocated
 * buffer.
 * Caller needs to hold msc::buf_mutex.
 *
 * Return:	0 on successful deallocation or if there was no buffer to
 *		deallocate, -EBUSY if there are active users.
 */
static int msc_buffer_unlocked_free_unless_used(struct msc *msc)
{
	int count, ret = 0;

	count = atomic_cmpxchg(&msc->user_count, 0, -1);

	/* > 0: buffer is allocated and has users */
	if (count > 0)
		ret = -EBUSY;
	/* 0: buffer is allocated, no users */
	else if (!count)
		msc_buffer_free(msc);
	/* < 0: no buffer, nothing to do */

	return ret;
}

/**
 * msc_buffer_free_unless_used() - free a buffer unless it's in use
 * @msc:	MSC device
 *
 * This is a locked version of msc_buffer_unlocked_free_unless_used().
 */
static int msc_buffer_free_unless_used(struct msc *msc)
{
	int ret;

	mutex_lock(&msc->buf_mutex);
	ret = msc_buffer_unlocked_free_unless_used(msc);
	mutex_unlock(&msc->buf_mutex);

	return ret;
}

/**
 * msc_buffer_get_page() - get MSC buffer page at a given offset
 * @msc:	MSC device
 * @pgoff:	page offset into the storage buffer
 *
 * This traverses msc::win_list, so holding msc::buf_mutex is expected from
 * the caller.
 *
 * Return:	page if @pgoff corresponds to a valid buffer page or NULL.
 */
static struct page *msc_buffer_get_page(struct msc *msc, unsigned long pgoff)
{
	struct msc_window *win;

	if (msc->mode == MSC_MODE_SINGLE)
		return msc_buffer_contig_get_page(msc, pgoff);

	list_for_each_entry(win, &msc->win_list, entry)
		if (pgoff >= win->pgoff && pgoff < win->pgoff + win->nr_blocks)
			goto found;

	return NULL;

found:
	pgoff -= win->pgoff;
	return virt_to_page(win->block[pgoff].bdesc);
}

/**
 * struct msc_win_to_user_struct - data for copy_to_user() callback
 * @buf:	userspace buffer to copy data to
 * @offset:	running offset
 */
struct msc_win_to_user_struct {
	char __user	*buf;
	unsigned long	offset;
};

/**
 * msc_win_to_user() - iterator for msc_buffer_iterate() to copy data to user
 * @data:	callback's private data
 * @src:	source buffer
 * @len:	amount of data to copy from the source buffer
 */
static unsigned long msc_win_to_user(void *data, void *src, size_t len)
{
	struct msc_win_to_user_struct *u = data;
	unsigned long ret;

	ret = copy_to_user(u->buf + u->offset, src, len);
	u->offset += len - ret;

	return ret;
}


/*
 * file operations' callbacks
 */

static int intel_th_msc_open(struct inode *inode, struct file *file)
{
	struct intel_th_device *thdev = file->private_data;
	struct msc *msc = dev_get_drvdata(&thdev->dev);
	struct msc_iter *iter;

	if (!capable(CAP_SYS_RAWIO))
		return -EPERM;

	iter = msc_iter_install(msc);
	if (IS_ERR(iter))
		return PTR_ERR(iter);

	file->private_data = iter;

	return nonseekable_open(inode, file);
}

static int intel_th_msc_release(struct inode *inode, struct file *file)
{
	struct msc_iter *iter = file->private_data;
	struct msc *msc = iter->msc;

	msc_iter_remove(iter, msc);

	return 0;
}

static ssize_t
msc_single_to_user(struct msc *msc, char __user *buf, loff_t off, size_t len)
{
	unsigned long size = msc->nr_pages << PAGE_SHIFT, rem = len;
	unsigned long start = off, tocopy = 0;

	if (msc->single_wrap) {
		start += msc->single_sz;
		if (start < size) {
			tocopy = min(rem, size - start);
			if (copy_to_user(buf, msc->base + start, tocopy))
				return -EFAULT;

			buf += tocopy;
			rem -= tocopy;
			start += tocopy;
		}

		start &= size - 1;
		if (rem) {
			tocopy = min(rem, msc->single_sz - start);
			if (copy_to_user(buf, msc->base + start, tocopy))
				return -EFAULT;

			rem -= tocopy;
		}

		return len - rem;
	}

	if (copy_to_user(buf, msc->base + start, rem))
		return -EFAULT;

	return len;
}

static ssize_t intel_th_msc_read(struct file *file, char __user *buf,
				 size_t len, loff_t *ppos)
{
	struct msc_iter *iter = file->private_data;
	struct msc *msc = iter->msc;
	size_t size;
	loff_t off = *ppos;
	ssize_t ret = 0;

	if (!atomic_inc_unless_negative(&msc->user_count))
		return 0;

	if (msc->mode == MSC_MODE_SINGLE && !msc->single_wrap)
		size = msc->single_sz;
	else
		size = msc->nr_pages << PAGE_SHIFT;

	if (!size)
		goto put_count;

	if (off >= size)
		goto put_count;

	if (off + len >= size)
		len = size - off;

	if (msc->mode == MSC_MODE_SINGLE) {
		ret = msc_single_to_user(msc, buf, off, len);
		if (ret >= 0)
			*ppos += ret;
	} else if (msc->mode == MSC_MODE_MULTI) {
		struct msc_win_to_user_struct u = {
			.buf	= buf,
			.offset	= 0,
		};

		ret = msc_buffer_iterate(iter, len, &u, msc_win_to_user);
		if (ret >= 0)
			*ppos = iter->offset;
	} else {
		ret = -ENOTSUPP;
	}

put_count:
	atomic_dec(&msc->user_count);

	return ret;
}

/*
 * vm operations callbacks (vm_ops)
 */

static void msc_mmap_open(struct vm_area_struct *vma)
{
	struct msc_iter *iter = vma->vm_file->private_data;
	struct msc *msc = iter->msc;

	atomic_inc(&msc->mmap_count);
}

static void msc_mmap_close(struct vm_area_struct *vma)
{
	struct msc_iter *iter = vma->vm_file->private_data;
	struct msc *msc = iter->msc;
	unsigned long pg;

	if (!atomic_dec_and_mutex_lock(&msc->mmap_count, &msc->buf_mutex))
		return;

	/* drop page _refcounts */
	for (pg = 0; pg < msc->nr_pages; pg++) {
		struct page *page = msc_buffer_get_page(msc, pg);

		if (WARN_ON_ONCE(!page))
			continue;

		if (page->mapping)
			page->mapping = NULL;
	}

	/* last mapping -- drop user_count */
	atomic_dec(&msc->user_count);
	mutex_unlock(&msc->buf_mutex);
}

static int msc_mmap_fault(struct vm_fault *vmf)
{
	struct msc_iter *iter = vmf->vma->vm_file->private_data;
	struct msc *msc = iter->msc;

	vmf->page = msc_buffer_get_page(msc, vmf->pgoff);
	if (!vmf->page)
		return VM_FAULT_SIGBUS;

	get_page(vmf->page);
	vmf->page->mapping = vmf->vma->vm_file->f_mapping;
	vmf->page->index = vmf->pgoff;

	return 0;
}

static const struct vm_operations_struct msc_mmap_ops = {
	.open	= msc_mmap_open,
	.close	= msc_mmap_close,
	.fault	= msc_mmap_fault,
};

static int intel_th_msc_mmap(struct file *file, struct vm_area_struct *vma)
{
	unsigned long size = vma->vm_end - vma->vm_start;
	struct msc_iter *iter = vma->vm_file->private_data;
	struct msc *msc = iter->msc;
	int ret = -EINVAL;

	if (!size || offset_in_page(size))
		return -EINVAL;

	if (vma->vm_pgoff)
		return -EINVAL;

	/* grab user_count once per mmap; drop in msc_mmap_close() */
	if (!atomic_inc_unless_negative(&msc->user_count))
		return -EINVAL;

	if (msc->mode != MSC_MODE_SINGLE &&
	    msc->mode != MSC_MODE_MULTI)
		goto out;

	if (size >> PAGE_SHIFT != msc->nr_pages)
		goto out;

	atomic_set(&msc->mmap_count, 1);
	ret = 0;

out:
	if (ret)
		atomic_dec(&msc->user_count);

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_flags |= VM_DONTEXPAND | VM_DONTCOPY;
	vma->vm_ops = &msc_mmap_ops;
	return ret;
}

static const struct file_operations intel_th_msc_fops = {
	.open		= intel_th_msc_open,
	.release	= intel_th_msc_release,
	.read		= intel_th_msc_read,
	.mmap		= intel_th_msc_mmap,
	.llseek		= no_llseek,
	.owner		= THIS_MODULE,
};

static int intel_th_msc_init(struct msc *msc)
{
	atomic_set(&msc->user_count, -1);

	msc->mode = MSC_MODE_MULTI;
	mutex_init(&msc->buf_mutex);
	INIT_LIST_HEAD(&msc->win_list);
	INIT_LIST_HEAD(&msc->iter_list);

	msc->burst_len =
		(ioread32(msc->reg_base + REG_MSU_MSC0CTL) & MSC_LEN) >>
		__ffs(MSC_LEN);

	return 0;
}

static const char * const msc_mode[] = {
	[MSC_MODE_SINGLE]	= "single",
	[MSC_MODE_MULTI]	= "multi",
	[MSC_MODE_EXI]		= "ExI",
	[MSC_MODE_DEBUG]	= "debug",
};

static ssize_t
wrap_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct msc *msc = dev_get_drvdata(dev);

	return scnprintf(buf, PAGE_SIZE, "%d\n", msc->wrap);
}

static ssize_t
wrap_store(struct device *dev, struct device_attribute *attr, const char *buf,
	   size_t size)
{
	struct msc *msc = dev_get_drvdata(dev);
	unsigned long val;
	int ret;

	ret = kstrtoul(buf, 10, &val);
	if (ret)
		return ret;

	msc->wrap = !!val;

	return size;
}

static DEVICE_ATTR_RW(wrap);

static ssize_t
mode_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct msc *msc = dev_get_drvdata(dev);

	return scnprintf(buf, PAGE_SIZE, "%s\n", msc_mode[msc->mode]);
}

static ssize_t
mode_store(struct device *dev, struct device_attribute *attr, const char *buf,
	   size_t size)
{
	struct msc *msc = dev_get_drvdata(dev);
	size_t len = size;
	char *cp;
	int i, ret;

	if (!capable(CAP_SYS_RAWIO))
		return -EPERM;

	cp = memchr(buf, '\n', len);
	if (cp)
		len = cp - buf;

	for (i = 0; i < ARRAY_SIZE(msc_mode); i++)
		if (!strncmp(msc_mode[i], buf, len))
			goto found;

	return -EINVAL;

found:
	mutex_lock(&msc->buf_mutex);
	ret = msc_buffer_unlocked_free_unless_used(msc);
	if (!ret)
		msc->mode = i;
	mutex_unlock(&msc->buf_mutex);

	return ret ? ret : size;
}

static DEVICE_ATTR_RW(mode);

static ssize_t
nr_pages_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct msc *msc = dev_get_drvdata(dev);
	struct msc_window *win;
	size_t count = 0;

	mutex_lock(&msc->buf_mutex);

	if (msc->mode == MSC_MODE_SINGLE)
		count = scnprintf(buf, PAGE_SIZE, "%ld\n", msc->nr_pages);
	else if (msc->mode == MSC_MODE_MULTI) {
		list_for_each_entry(win, &msc->win_list, entry) {
			count += scnprintf(buf + count, PAGE_SIZE - count,
					   "%d%c", win->nr_blocks,
					   msc_is_last_win(win) ? '\n' : ',');
		}
	} else {
		count = scnprintf(buf, PAGE_SIZE, "unsupported\n");
	}

	mutex_unlock(&msc->buf_mutex);

	return count;
}

static ssize_t
nr_pages_store(struct device *dev, struct device_attribute *attr,
	       const char *buf, size_t size)
{
	struct msc *msc = dev_get_drvdata(dev);
	unsigned long val, *win = NULL, *rewin;
	size_t len = size;
	const char *p = buf;
	char *end, *s;
	int ret, nr_wins = 0;

	if (!capable(CAP_SYS_RAWIO))
		return -EPERM;

	ret = msc_buffer_free_unless_used(msc);
	if (ret)
		return ret;

	/* scan the comma-separated list of allocation sizes */
	end = memchr(buf, '\n', len);
	if (end)
		len = end - buf;

	do {
		end = memchr(p, ',', len);
		s = kstrndup(p, end ? end - p : len, GFP_KERNEL);
		if (!s) {
			ret = -ENOMEM;
			goto free_win;
		}

		ret = kstrtoul(s, 10, &val);
		kfree(s);

		if (ret || !val)
			goto free_win;

		if (nr_wins && msc->mode == MSC_MODE_SINGLE) {
			ret = -EINVAL;
			goto free_win;
		}

		nr_wins++;
		rewin = krealloc(win, sizeof(*win) * nr_wins, GFP_KERNEL);
		if (!rewin) {
			kfree(win);
			return -ENOMEM;
		}

		win = rewin;
		win[nr_wins - 1] = val;

		if (!end)
			break;

		len -= end - p;
		p = end + 1;
	} while (len);

	mutex_lock(&msc->buf_mutex);
	ret = msc_buffer_alloc(msc, win, nr_wins);
	mutex_unlock(&msc->buf_mutex);

free_win:
	kfree(win);

	return ret ? ret : size;
}

static DEVICE_ATTR_RW(nr_pages);

static struct attribute *msc_output_attrs[] = {
	&dev_attr_wrap.attr,
	&dev_attr_mode.attr,
	&dev_attr_nr_pages.attr,
	NULL,
};

static struct attribute_group msc_output_group = {
	.attrs	= msc_output_attrs,
};

static int intel_th_msc_probe(struct intel_th_device *thdev)
{
	struct device *dev = &thdev->dev;
	struct resource *res;
	struct msc *msc;
	void __iomem *base;
	int err;

	res = intel_th_device_get_resource(thdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENODEV;

	base = devm_ioremap(dev, res->start, resource_size(res));
	if (!base)
		return -ENOMEM;

	msc = devm_kzalloc(dev, sizeof(*msc), GFP_KERNEL);
	if (!msc)
		return -ENOMEM;

	msc->index = thdev->id;

	msc->thdev = thdev;
	msc->reg_base = base + msc->index * 0x100;

	err = intel_th_msc_init(msc);
	if (err)
		return err;

	dev_set_drvdata(dev, msc);

	return 0;
}

static void intel_th_msc_remove(struct intel_th_device *thdev)
{
	struct msc *msc = dev_get_drvdata(&thdev->dev);
	int ret;

	intel_th_msc_deactivate(thdev);

	/*
	 * Buffers should not be used at this point except if the
	 * output character device is still open and the parent
	 * device gets detached from its bus, which is a FIXME.
	 */
	ret = msc_buffer_free_unless_used(msc);
	WARN_ON_ONCE(ret);
}

static struct intel_th_driver intel_th_msc_driver = {
	.probe	= intel_th_msc_probe,
	.remove	= intel_th_msc_remove,
	.activate	= intel_th_msc_activate,
	.deactivate	= intel_th_msc_deactivate,
	.fops	= &intel_th_msc_fops,
	.attr_group	= &msc_output_group,
	.driver	= {
		.name	= "msc",
		.owner	= THIS_MODULE,
	},
};

module_driver(intel_th_msc_driver,
	      intel_th_driver_register,
	      intel_th_driver_unregister);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Intel(R) Trace Hub Memory Storage Unit driver");
MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");