summaryrefslogtreecommitdiff
path: root/drivers/most/core.c
blob: f13d0e14a48b6474c7f0134eaadaefeb727ebc85 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * core.c - Implementation of core module of MOST Linux driver stack
 *
 * Copyright (C) 2013-2020 Microchip Technology Germany II GmbH & Co. KG
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/kobject.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <linux/sysfs.h>
#include <linux/kthread.h>
#include <linux/dma-mapping.h>
#include <linux/idr.h>
#include <linux/most.h>

#define MAX_CHANNELS	64
#define STRING_SIZE	80

static struct ida mdev_id;
static int dummy_num_buffers;
static struct list_head comp_list;

struct pipe {
	struct most_component *comp;
	int refs;
	int num_buffers;
};

struct most_channel {
	struct device dev;
	struct completion cleanup;
	atomic_t mbo_ref;
	atomic_t mbo_nq_level;
	u16 channel_id;
	char name[STRING_SIZE];
	bool is_poisoned;
	struct mutex start_mutex; /* channel activation synchronization */
	struct mutex nq_mutex; /* nq thread synchronization */
	int is_starving;
	struct most_interface *iface;
	struct most_channel_config cfg;
	bool keep_mbo;
	bool enqueue_halt;
	struct list_head fifo;
	spinlock_t fifo_lock; /* fifo access synchronization */
	struct list_head halt_fifo;
	struct list_head list;
	struct pipe pipe0;
	struct pipe pipe1;
	struct list_head trash_fifo;
	struct task_struct *hdm_enqueue_task;
	wait_queue_head_t hdm_fifo_wq;

};

#define to_channel(d) container_of(d, struct most_channel, dev)

struct interface_private {
	int dev_id;
	char name[STRING_SIZE];
	struct most_channel *channel[MAX_CHANNELS];
	struct list_head channel_list;
};

static const struct {
	int most_ch_data_type;
	const char *name;
} ch_data_type[] = {
	{ MOST_CH_CONTROL, "control" },
	{ MOST_CH_ASYNC, "async" },
	{ MOST_CH_SYNC, "sync" },
	{ MOST_CH_ISOC, "isoc"},
	{ MOST_CH_ISOC, "isoc_avp"},
};

/**
 * list_pop_mbo - retrieves the first MBO of the list and removes it
 * @ptr: the list head to grab the MBO from.
 */
#define list_pop_mbo(ptr)						\
({									\
	struct mbo *_mbo = list_first_entry(ptr, struct mbo, list);	\
	list_del(&_mbo->list);						\
	_mbo;								\
})

/**
 * most_free_mbo_coherent - free an MBO and its coherent buffer
 * @mbo: most buffer
 */
static void most_free_mbo_coherent(struct mbo *mbo)
{
	struct most_channel *c = mbo->context;
	u16 const coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;

	if (c->iface->dma_free)
		c->iface->dma_free(mbo, coherent_buf_size);
	else
		kfree(mbo->virt_address);
	kfree(mbo);
	if (atomic_sub_and_test(1, &c->mbo_ref))
		complete(&c->cleanup);
}

/**
 * flush_channel_fifos - clear the channel fifos
 * @c: pointer to channel object
 */
static void flush_channel_fifos(struct most_channel *c)
{
	unsigned long flags, hf_flags;
	struct mbo *mbo, *tmp;

	if (list_empty(&c->fifo) && list_empty(&c->halt_fifo))
		return;

	spin_lock_irqsave(&c->fifo_lock, flags);
	list_for_each_entry_safe(mbo, tmp, &c->fifo, list) {
		list_del(&mbo->list);
		spin_unlock_irqrestore(&c->fifo_lock, flags);
		most_free_mbo_coherent(mbo);
		spin_lock_irqsave(&c->fifo_lock, flags);
	}
	spin_unlock_irqrestore(&c->fifo_lock, flags);

	spin_lock_irqsave(&c->fifo_lock, hf_flags);
	list_for_each_entry_safe(mbo, tmp, &c->halt_fifo, list) {
		list_del(&mbo->list);
		spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
		most_free_mbo_coherent(mbo);
		spin_lock_irqsave(&c->fifo_lock, hf_flags);
	}
	spin_unlock_irqrestore(&c->fifo_lock, hf_flags);

	if (unlikely((!list_empty(&c->fifo) || !list_empty(&c->halt_fifo))))
		dev_warn(&c->dev, "Channel or trash fifo not empty\n");
}

/**
 * flush_trash_fifo - clear the trash fifo
 * @c: pointer to channel object
 */
static int flush_trash_fifo(struct most_channel *c)
{
	struct mbo *mbo, *tmp;
	unsigned long flags;

	spin_lock_irqsave(&c->fifo_lock, flags);
	list_for_each_entry_safe(mbo, tmp, &c->trash_fifo, list) {
		list_del(&mbo->list);
		spin_unlock_irqrestore(&c->fifo_lock, flags);
		most_free_mbo_coherent(mbo);
		spin_lock_irqsave(&c->fifo_lock, flags);
	}
	spin_unlock_irqrestore(&c->fifo_lock, flags);
	return 0;
}

static ssize_t available_directions_show(struct device *dev,
					 struct device_attribute *attr,
					 char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	strcpy(buf, "");
	if (c->iface->channel_vector[i].direction & MOST_CH_RX)
		strcat(buf, "rx ");
	if (c->iface->channel_vector[i].direction & MOST_CH_TX)
		strcat(buf, "tx ");
	strcat(buf, "\n");
	return strlen(buf);
}

static ssize_t available_datatypes_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	strcpy(buf, "");
	if (c->iface->channel_vector[i].data_type & MOST_CH_CONTROL)
		strcat(buf, "control ");
	if (c->iface->channel_vector[i].data_type & MOST_CH_ASYNC)
		strcat(buf, "async ");
	if (c->iface->channel_vector[i].data_type & MOST_CH_SYNC)
		strcat(buf, "sync ");
	if (c->iface->channel_vector[i].data_type & MOST_CH_ISOC)
		strcat(buf, "isoc ");
	strcat(buf, "\n");
	return strlen(buf);
}

static ssize_t number_of_packet_buffers_show(struct device *dev,
					     struct device_attribute *attr,
					     char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	return snprintf(buf, PAGE_SIZE, "%d\n",
			c->iface->channel_vector[i].num_buffers_packet);
}

static ssize_t number_of_stream_buffers_show(struct device *dev,
					     struct device_attribute *attr,
					     char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	return snprintf(buf, PAGE_SIZE, "%d\n",
			c->iface->channel_vector[i].num_buffers_streaming);
}

static ssize_t size_of_packet_buffer_show(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	return snprintf(buf, PAGE_SIZE, "%d\n",
			c->iface->channel_vector[i].buffer_size_packet);
}

static ssize_t size_of_stream_buffer_show(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	struct most_channel *c = to_channel(dev);
	unsigned int i = c->channel_id;

	return snprintf(buf, PAGE_SIZE, "%d\n",
			c->iface->channel_vector[i].buffer_size_streaming);
}

static ssize_t channel_starving_show(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->is_starving);
}

static ssize_t set_number_of_buffers_show(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.num_buffers);
}

static ssize_t set_buffer_size_show(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.buffer_size);
}

static ssize_t set_direction_show(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{
	struct most_channel *c = to_channel(dev);

	if (c->cfg.direction & MOST_CH_TX)
		return snprintf(buf, PAGE_SIZE, "tx\n");
	else if (c->cfg.direction & MOST_CH_RX)
		return snprintf(buf, PAGE_SIZE, "rx\n");
	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
}

static ssize_t set_datatype_show(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	int i;
	struct most_channel *c = to_channel(dev);

	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
		if (c->cfg.data_type & ch_data_type[i].most_ch_data_type)
			return snprintf(buf, PAGE_SIZE, "%s",
					ch_data_type[i].name);
	}
	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
}

static ssize_t set_subbuffer_size_show(struct device *dev,
				       struct device_attribute *attr,
				       char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.subbuffer_size);
}

static ssize_t set_packets_per_xact_show(struct device *dev,
					 struct device_attribute *attr,
					 char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.packets_per_xact);
}

static ssize_t set_dbr_size_show(struct device *dev,
				 struct device_attribute *attr, char *buf)
{
	struct most_channel *c = to_channel(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.dbr_size);
}

#define to_dev_attr(a) container_of(a, struct device_attribute, attr)
static umode_t channel_attr_is_visible(struct kobject *kobj,
				       struct attribute *attr, int index)
{
	struct device_attribute *dev_attr = to_dev_attr(attr);
	struct device *dev = kobj_to_dev(kobj);
	struct most_channel *c = to_channel(dev);

	if (!strcmp(dev_attr->attr.name, "set_dbr_size") &&
	    (c->iface->interface != ITYPE_MEDIALB_DIM2))
		return 0;
	if (!strcmp(dev_attr->attr.name, "set_packets_per_xact") &&
	    (c->iface->interface != ITYPE_USB))
		return 0;

	return attr->mode;
}

#define DEV_ATTR(_name)  (&dev_attr_##_name.attr)

static DEVICE_ATTR_RO(available_directions);
static DEVICE_ATTR_RO(available_datatypes);
static DEVICE_ATTR_RO(number_of_packet_buffers);
static DEVICE_ATTR_RO(number_of_stream_buffers);
static DEVICE_ATTR_RO(size_of_stream_buffer);
static DEVICE_ATTR_RO(size_of_packet_buffer);
static DEVICE_ATTR_RO(channel_starving);
static DEVICE_ATTR_RO(set_buffer_size);
static DEVICE_ATTR_RO(set_number_of_buffers);
static DEVICE_ATTR_RO(set_direction);
static DEVICE_ATTR_RO(set_datatype);
static DEVICE_ATTR_RO(set_subbuffer_size);
static DEVICE_ATTR_RO(set_packets_per_xact);
static DEVICE_ATTR_RO(set_dbr_size);

static struct attribute *channel_attrs[] = {
	DEV_ATTR(available_directions),
	DEV_ATTR(available_datatypes),
	DEV_ATTR(number_of_packet_buffers),
	DEV_ATTR(number_of_stream_buffers),
	DEV_ATTR(size_of_stream_buffer),
	DEV_ATTR(size_of_packet_buffer),
	DEV_ATTR(channel_starving),
	DEV_ATTR(set_buffer_size),
	DEV_ATTR(set_number_of_buffers),
	DEV_ATTR(set_direction),
	DEV_ATTR(set_datatype),
	DEV_ATTR(set_subbuffer_size),
	DEV_ATTR(set_packets_per_xact),
	DEV_ATTR(set_dbr_size),
	NULL,
};

static const struct attribute_group channel_attr_group = {
	.attrs = channel_attrs,
	.is_visible = channel_attr_is_visible,
};

static const struct attribute_group *channel_attr_groups[] = {
	&channel_attr_group,
	NULL,
};

static ssize_t description_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	struct most_interface *iface = dev_get_drvdata(dev);

	return snprintf(buf, PAGE_SIZE, "%s\n", iface->description);
}

static ssize_t interface_show(struct device *dev,
			      struct device_attribute *attr,
			      char *buf)
{
	struct most_interface *iface = dev_get_drvdata(dev);

	switch (iface->interface) {
	case ITYPE_LOOPBACK:
		return snprintf(buf, PAGE_SIZE, "loopback\n");
	case ITYPE_I2C:
		return snprintf(buf, PAGE_SIZE, "i2c\n");
	case ITYPE_I2S:
		return snprintf(buf, PAGE_SIZE, "i2s\n");
	case ITYPE_TSI:
		return snprintf(buf, PAGE_SIZE, "tsi\n");
	case ITYPE_HBI:
		return snprintf(buf, PAGE_SIZE, "hbi\n");
	case ITYPE_MEDIALB_DIM:
		return snprintf(buf, PAGE_SIZE, "mlb_dim\n");
	case ITYPE_MEDIALB_DIM2:
		return snprintf(buf, PAGE_SIZE, "mlb_dim2\n");
	case ITYPE_USB:
		return snprintf(buf, PAGE_SIZE, "usb\n");
	case ITYPE_PCIE:
		return snprintf(buf, PAGE_SIZE, "pcie\n");
	}
	return snprintf(buf, PAGE_SIZE, "unknown\n");
}

static DEVICE_ATTR_RO(description);
static DEVICE_ATTR_RO(interface);

static struct attribute *interface_attrs[] = {
	DEV_ATTR(description),
	DEV_ATTR(interface),
	NULL,
};

static const struct attribute_group interface_attr_group = {
	.attrs = interface_attrs,
};

static const struct attribute_group *interface_attr_groups[] = {
	&interface_attr_group,
	NULL,
};

static struct most_component *match_component(char *name)
{
	struct most_component *comp;

	list_for_each_entry(comp, &comp_list, list) {
		if (!strcmp(comp->name, name))
			return comp;
	}
	return NULL;
}

struct show_links_data {
	int offs;
	char *buf;
};

static int print_links(struct device *dev, void *data)
{
	struct show_links_data *d = data;
	int offs = d->offs;
	char *buf = d->buf;
	struct most_channel *c;
	struct most_interface *iface = dev_get_drvdata(dev);

	list_for_each_entry(c, &iface->p->channel_list, list) {
		if (c->pipe0.comp) {
			offs += scnprintf(buf + offs,
					 PAGE_SIZE - offs,
					 "%s:%s:%s\n",
					 c->pipe0.comp->name,
					 dev_name(iface->dev),
					 dev_name(&c->dev));
		}
		if (c->pipe1.comp) {
			offs += scnprintf(buf + offs,
					 PAGE_SIZE - offs,
					 "%s:%s:%s\n",
					 c->pipe1.comp->name,
					 dev_name(iface->dev),
					 dev_name(&c->dev));
		}
	}
	d->offs = offs;
	return 0;
}

static int most_match(struct device *dev, struct device_driver *drv)
{
	if (!strcmp(dev_name(dev), "most"))
		return 0;
	else
		return 1;
}

static const struct bus_type mostbus = {
	.name = "most",
	.match = most_match,
};

static ssize_t links_show(struct device_driver *drv, char *buf)
{
	struct show_links_data d = { .buf = buf };

	bus_for_each_dev(&mostbus, NULL, &d, print_links);
	return d.offs;
}

static ssize_t components_show(struct device_driver *drv, char *buf)
{
	struct most_component *comp;
	int offs = 0;

	list_for_each_entry(comp, &comp_list, list) {
		offs += scnprintf(buf + offs, PAGE_SIZE - offs, "%s\n",
				 comp->name);
	}
	return offs;
}

/**
 * get_channel - get pointer to channel
 * @mdev: name of the device interface
 * @mdev_ch: name of channel
 */
static struct most_channel *get_channel(char *mdev, char *mdev_ch)
{
	struct device *dev = NULL;
	struct most_interface *iface;
	struct most_channel *c, *tmp;

	dev = bus_find_device_by_name(&mostbus, NULL, mdev);
	if (!dev)
		return NULL;
	put_device(dev);
	iface = dev_get_drvdata(dev);
	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
		if (!strcmp(dev_name(&c->dev), mdev_ch))
			return c;
	}
	return NULL;
}

static
inline int link_channel_to_component(struct most_channel *c,
				     struct most_component *comp,
				     char *name,
				     char *comp_param)
{
	int ret;
	struct most_component **comp_ptr;

	if (!c->pipe0.comp)
		comp_ptr = &c->pipe0.comp;
	else if (!c->pipe1.comp)
		comp_ptr = &c->pipe1.comp;
	else
		return -ENOSPC;

	*comp_ptr = comp;
	ret = comp->probe_channel(c->iface, c->channel_id, &c->cfg, name,
				  comp_param);
	if (ret) {
		*comp_ptr = NULL;
		return ret;
	}
	return 0;
}

int most_set_cfg_buffer_size(char *mdev, char *mdev_ch, u16 val)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	c->cfg.buffer_size = val;
	return 0;
}

int most_set_cfg_subbuffer_size(char *mdev, char *mdev_ch, u16 val)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	c->cfg.subbuffer_size = val;
	return 0;
}

int most_set_cfg_dbr_size(char *mdev, char *mdev_ch, u16 val)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	c->cfg.dbr_size = val;
	return 0;
}

int most_set_cfg_num_buffers(char *mdev, char *mdev_ch, u16 val)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	c->cfg.num_buffers = val;
	return 0;
}

int most_set_cfg_datatype(char *mdev, char *mdev_ch, char *buf)
{
	int i;
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
		if (!strcmp(buf, ch_data_type[i].name)) {
			c->cfg.data_type = ch_data_type[i].most_ch_data_type;
			break;
		}
	}

	if (i == ARRAY_SIZE(ch_data_type))
		dev_warn(&c->dev, "Invalid attribute settings\n");
	return 0;
}

int most_set_cfg_direction(char *mdev, char *mdev_ch, char *buf)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	if (!strcmp(buf, "dir_rx")) {
		c->cfg.direction = MOST_CH_RX;
	} else if (!strcmp(buf, "rx")) {
		c->cfg.direction = MOST_CH_RX;
	} else if (!strcmp(buf, "dir_tx")) {
		c->cfg.direction = MOST_CH_TX;
	} else if (!strcmp(buf, "tx")) {
		c->cfg.direction = MOST_CH_TX;
	} else {
		dev_err(&c->dev, "Invalid direction\n");
		return -ENODATA;
	}
	return 0;
}

int most_set_cfg_packets_xact(char *mdev, char *mdev_ch, u16 val)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);

	if (!c)
		return -ENODEV;
	c->cfg.packets_per_xact = val;
	return 0;
}

int most_cfg_complete(char *comp_name)
{
	struct most_component *comp;

	comp = match_component(comp_name);
	if (!comp)
		return -ENODEV;

	return comp->cfg_complete();
}

int most_add_link(char *mdev, char *mdev_ch, char *comp_name, char *link_name,
		  char *comp_param)
{
	struct most_channel *c = get_channel(mdev, mdev_ch);
	struct most_component *comp = match_component(comp_name);

	if (!c || !comp)
		return -ENODEV;

	return link_channel_to_component(c, comp, link_name, comp_param);
}

int most_remove_link(char *mdev, char *mdev_ch, char *comp_name)
{
	struct most_channel *c;
	struct most_component *comp;

	comp = match_component(comp_name);
	if (!comp)
		return -ENODEV;
	c = get_channel(mdev, mdev_ch);
	if (!c)
		return -ENODEV;

	if (comp->disconnect_channel(c->iface, c->channel_id))
		return -EIO;
	if (c->pipe0.comp == comp)
		c->pipe0.comp = NULL;
	if (c->pipe1.comp == comp)
		c->pipe1.comp = NULL;
	return 0;
}

#define DRV_ATTR(_name)  (&driver_attr_##_name.attr)

static DRIVER_ATTR_RO(links);
static DRIVER_ATTR_RO(components);

static struct attribute *mc_attrs[] = {
	DRV_ATTR(links),
	DRV_ATTR(components),
	NULL,
};

static const struct attribute_group mc_attr_group = {
	.attrs = mc_attrs,
};

static const struct attribute_group *mc_attr_groups[] = {
	&mc_attr_group,
	NULL,
};

static struct device_driver mostbus_driver = {
	.name = "most_core",
	.bus = &mostbus,
	.groups = mc_attr_groups,
};

static inline void trash_mbo(struct mbo *mbo)
{
	unsigned long flags;
	struct most_channel *c = mbo->context;

	spin_lock_irqsave(&c->fifo_lock, flags);
	list_add(&mbo->list, &c->trash_fifo);
	spin_unlock_irqrestore(&c->fifo_lock, flags);
}

static bool hdm_mbo_ready(struct most_channel *c)
{
	bool empty;

	if (c->enqueue_halt)
		return false;

	spin_lock_irq(&c->fifo_lock);
	empty = list_empty(&c->halt_fifo);
	spin_unlock_irq(&c->fifo_lock);

	return !empty;
}

static void nq_hdm_mbo(struct mbo *mbo)
{
	unsigned long flags;
	struct most_channel *c = mbo->context;

	spin_lock_irqsave(&c->fifo_lock, flags);
	list_add_tail(&mbo->list, &c->halt_fifo);
	spin_unlock_irqrestore(&c->fifo_lock, flags);
	wake_up_interruptible(&c->hdm_fifo_wq);
}

static int hdm_enqueue_thread(void *data)
{
	struct most_channel *c = data;
	struct mbo *mbo;
	int ret;
	typeof(c->iface->enqueue) enqueue = c->iface->enqueue;

	while (likely(!kthread_should_stop())) {
		wait_event_interruptible(c->hdm_fifo_wq,
					 hdm_mbo_ready(c) ||
					 kthread_should_stop());

		mutex_lock(&c->nq_mutex);
		spin_lock_irq(&c->fifo_lock);
		if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
			spin_unlock_irq(&c->fifo_lock);
			mutex_unlock(&c->nq_mutex);
			continue;
		}

		mbo = list_pop_mbo(&c->halt_fifo);
		spin_unlock_irq(&c->fifo_lock);

		if (c->cfg.direction == MOST_CH_RX)
			mbo->buffer_length = c->cfg.buffer_size;

		ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
		mutex_unlock(&c->nq_mutex);

		if (unlikely(ret)) {
			dev_err(&c->dev, "Buffer enqueue failed\n");
			nq_hdm_mbo(mbo);
			c->hdm_enqueue_task = NULL;
			return 0;
		}
	}

	return 0;
}

static int run_enqueue_thread(struct most_channel *c, int channel_id)
{
	struct task_struct *task =
		kthread_run(hdm_enqueue_thread, c, "hdm_fifo_%d",
			    channel_id);

	if (IS_ERR(task))
		return PTR_ERR(task);

	c->hdm_enqueue_task = task;
	return 0;
}

/**
 * arm_mbo - recycle MBO for further usage
 * @mbo: most buffer
 *
 * This puts an MBO back to the list to have it ready for up coming
 * tx transactions.
 *
 * In case the MBO belongs to a channel that recently has been
 * poisoned, the MBO is scheduled to be trashed.
 * Calls the completion handler of an attached component.
 */
static void arm_mbo(struct mbo *mbo)
{
	unsigned long flags;
	struct most_channel *c;

	c = mbo->context;

	if (c->is_poisoned) {
		trash_mbo(mbo);
		return;
	}

	spin_lock_irqsave(&c->fifo_lock, flags);
	++*mbo->num_buffers_ptr;
	list_add_tail(&mbo->list, &c->fifo);
	spin_unlock_irqrestore(&c->fifo_lock, flags);

	if (c->pipe0.refs && c->pipe0.comp->tx_completion)
		c->pipe0.comp->tx_completion(c->iface, c->channel_id);

	if (c->pipe1.refs && c->pipe1.comp->tx_completion)
		c->pipe1.comp->tx_completion(c->iface, c->channel_id);
}

/**
 * arm_mbo_chain - helper function that arms an MBO chain for the HDM
 * @c: pointer to interface channel
 * @dir: direction of the channel
 * @compl: pointer to completion function
 *
 * This allocates buffer objects including the containing DMA coherent
 * buffer and puts them in the fifo.
 * Buffers of Rx channels are put in the kthread fifo, hence immediately
 * submitted to the HDM.
 *
 * Returns the number of allocated and enqueued MBOs.
 */
static int arm_mbo_chain(struct most_channel *c, int dir,
			 void (*compl)(struct mbo *))
{
	unsigned int i;
	struct mbo *mbo;
	unsigned long flags;
	u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;

	atomic_set(&c->mbo_nq_level, 0);

	for (i = 0; i < c->cfg.num_buffers; i++) {
		mbo = kzalloc(sizeof(*mbo), GFP_KERNEL);
		if (!mbo)
			goto flush_fifos;

		mbo->context = c;
		mbo->ifp = c->iface;
		mbo->hdm_channel_id = c->channel_id;
		if (c->iface->dma_alloc) {
			mbo->virt_address =
				c->iface->dma_alloc(mbo, coherent_buf_size);
		} else {
			mbo->virt_address =
				kzalloc(coherent_buf_size, GFP_KERNEL);
		}
		if (!mbo->virt_address)
			goto release_mbo;

		mbo->complete = compl;
		mbo->num_buffers_ptr = &dummy_num_buffers;
		if (dir == MOST_CH_RX) {
			nq_hdm_mbo(mbo);
			atomic_inc(&c->mbo_nq_level);
		} else {
			spin_lock_irqsave(&c->fifo_lock, flags);
			list_add_tail(&mbo->list, &c->fifo);
			spin_unlock_irqrestore(&c->fifo_lock, flags);
		}
	}
	return c->cfg.num_buffers;

release_mbo:
	kfree(mbo);

flush_fifos:
	flush_channel_fifos(c);
	return 0;
}

/**
 * most_submit_mbo - submits an MBO to fifo
 * @mbo: most buffer
 */
void most_submit_mbo(struct mbo *mbo)
{
	if (WARN_ONCE(!mbo || !mbo->context,
		      "Bad buffer or missing channel reference\n"))
		return;

	nq_hdm_mbo(mbo);
}
EXPORT_SYMBOL_GPL(most_submit_mbo);

/**
 * most_write_completion - write completion handler
 * @mbo: most buffer
 *
 * This recycles the MBO for further usage. In case the channel has been
 * poisoned, the MBO is scheduled to be trashed.
 */
static void most_write_completion(struct mbo *mbo)
{
	struct most_channel *c;

	c = mbo->context;
	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE)))
		trash_mbo(mbo);
	else
		arm_mbo(mbo);
}

int channel_has_mbo(struct most_interface *iface, int id,
		    struct most_component *comp)
{
	struct most_channel *c = iface->p->channel[id];
	unsigned long flags;
	int empty;

	if (unlikely(!c))
		return -EINVAL;

	if (c->pipe0.refs && c->pipe1.refs &&
	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
		return 0;

	spin_lock_irqsave(&c->fifo_lock, flags);
	empty = list_empty(&c->fifo);
	spin_unlock_irqrestore(&c->fifo_lock, flags);
	return !empty;
}
EXPORT_SYMBOL_GPL(channel_has_mbo);

/**
 * most_get_mbo - get pointer to an MBO of pool
 * @iface: pointer to interface instance
 * @id: channel ID
 * @comp: driver component
 *
 * This attempts to get a free buffer out of the channel fifo.
 * Returns a pointer to MBO on success or NULL otherwise.
 */
struct mbo *most_get_mbo(struct most_interface *iface, int id,
			 struct most_component *comp)
{
	struct mbo *mbo;
	struct most_channel *c;
	unsigned long flags;
	int *num_buffers_ptr;

	c = iface->p->channel[id];
	if (unlikely(!c))
		return NULL;

	if (c->pipe0.refs && c->pipe1.refs &&
	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
		return NULL;

	if (comp == c->pipe0.comp)
		num_buffers_ptr = &c->pipe0.num_buffers;
	else if (comp == c->pipe1.comp)
		num_buffers_ptr = &c->pipe1.num_buffers;
	else
		num_buffers_ptr = &dummy_num_buffers;

	spin_lock_irqsave(&c->fifo_lock, flags);
	if (list_empty(&c->fifo)) {
		spin_unlock_irqrestore(&c->fifo_lock, flags);
		return NULL;
	}
	mbo = list_pop_mbo(&c->fifo);
	--*num_buffers_ptr;
	spin_unlock_irqrestore(&c->fifo_lock, flags);

	mbo->num_buffers_ptr = num_buffers_ptr;
	mbo->buffer_length = c->cfg.buffer_size;
	return mbo;
}
EXPORT_SYMBOL_GPL(most_get_mbo);

/**
 * most_put_mbo - return buffer to pool
 * @mbo: most buffer
 */
void most_put_mbo(struct mbo *mbo)
{
	struct most_channel *c = mbo->context;

	if (c->cfg.direction == MOST_CH_TX) {
		arm_mbo(mbo);
		return;
	}
	nq_hdm_mbo(mbo);
	atomic_inc(&c->mbo_nq_level);
}
EXPORT_SYMBOL_GPL(most_put_mbo);

/**
 * most_read_completion - read completion handler
 * @mbo: most buffer
 *
 * This function is called by the HDM when data has been received from the
 * hardware and copied to the buffer of the MBO.
 *
 * In case the channel has been poisoned it puts the buffer in the trash queue.
 * Otherwise, it passes the buffer to an component for further processing.
 */
static void most_read_completion(struct mbo *mbo)
{
	struct most_channel *c = mbo->context;

	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE))) {
		trash_mbo(mbo);
		return;
	}

	if (mbo->status == MBO_E_INVAL) {
		nq_hdm_mbo(mbo);
		atomic_inc(&c->mbo_nq_level);
		return;
	}

	if (atomic_sub_and_test(1, &c->mbo_nq_level))
		c->is_starving = 1;

	if (c->pipe0.refs && c->pipe0.comp->rx_completion &&
	    c->pipe0.comp->rx_completion(mbo) == 0)
		return;

	if (c->pipe1.refs && c->pipe1.comp->rx_completion &&
	    c->pipe1.comp->rx_completion(mbo) == 0)
		return;

	most_put_mbo(mbo);
}

/**
 * most_start_channel - prepares a channel for communication
 * @iface: pointer to interface instance
 * @id: channel ID
 * @comp: driver component
 *
 * This prepares the channel for usage. Cross-checks whether the
 * channel's been properly configured.
 *
 * Returns 0 on success or error code otherwise.
 */
int most_start_channel(struct most_interface *iface, int id,
		       struct most_component *comp)
{
	int num_buffer;
	int ret;
	struct most_channel *c = iface->p->channel[id];

	if (unlikely(!c))
		return -EINVAL;

	mutex_lock(&c->start_mutex);
	if (c->pipe0.refs + c->pipe1.refs > 0)
		goto out; /* already started by another component */

	if (!try_module_get(iface->mod)) {
		dev_err(&c->dev, "Failed to acquire HDM lock\n");
		mutex_unlock(&c->start_mutex);
		return -ENOLCK;
	}

	c->cfg.extra_len = 0;
	if (c->iface->configure(c->iface, c->channel_id, &c->cfg)) {
		dev_err(&c->dev, "Channel configuration failed. Go check settings...\n");
		ret = -EINVAL;
		goto err_put_module;
	}

	init_waitqueue_head(&c->hdm_fifo_wq);

	if (c->cfg.direction == MOST_CH_RX)
		num_buffer = arm_mbo_chain(c, c->cfg.direction,
					   most_read_completion);
	else
		num_buffer = arm_mbo_chain(c, c->cfg.direction,
					   most_write_completion);
	if (unlikely(!num_buffer)) {
		ret = -ENOMEM;
		goto err_put_module;
	}

	ret = run_enqueue_thread(c, id);
	if (ret)
		goto err_put_module;

	c->is_starving = 0;
	c->pipe0.num_buffers = c->cfg.num_buffers / 2;
	c->pipe1.num_buffers = c->cfg.num_buffers - c->pipe0.num_buffers;
	atomic_set(&c->mbo_ref, num_buffer);

out:
	if (comp == c->pipe0.comp)
		c->pipe0.refs++;
	if (comp == c->pipe1.comp)
		c->pipe1.refs++;
	mutex_unlock(&c->start_mutex);
	return 0;

err_put_module:
	module_put(iface->mod);
	mutex_unlock(&c->start_mutex);
	return ret;
}
EXPORT_SYMBOL_GPL(most_start_channel);

/**
 * most_stop_channel - stops a running channel
 * @iface: pointer to interface instance
 * @id: channel ID
 * @comp: driver component
 */
int most_stop_channel(struct most_interface *iface, int id,
		      struct most_component *comp)
{
	struct most_channel *c;

	if (unlikely((!iface) || (id >= iface->num_channels) || (id < 0))) {
		pr_err("Bad interface or index out of range\n");
		return -EINVAL;
	}
	c = iface->p->channel[id];
	if (unlikely(!c))
		return -EINVAL;

	mutex_lock(&c->start_mutex);
	if (c->pipe0.refs + c->pipe1.refs >= 2)
		goto out;

	if (c->hdm_enqueue_task)
		kthread_stop(c->hdm_enqueue_task);
	c->hdm_enqueue_task = NULL;

	if (iface->mod)
		module_put(iface->mod);

	c->is_poisoned = true;
	if (c->iface->poison_channel(c->iface, c->channel_id)) {
		dev_err(&c->dev, "Failed to stop channel %d of interface %s\n", c->channel_id,
			c->iface->description);
		mutex_unlock(&c->start_mutex);
		return -EAGAIN;
	}
	flush_trash_fifo(c);
	flush_channel_fifos(c);

#ifdef CMPL_INTERRUPTIBLE
	if (wait_for_completion_interruptible(&c->cleanup)) {
		dev_err(&c->dev, "Interrupted while cleaning up channel %d\n", c->channel_id);
		mutex_unlock(&c->start_mutex);
		return -EINTR;
	}
#else
	wait_for_completion(&c->cleanup);
#endif
	c->is_poisoned = false;

out:
	if (comp == c->pipe0.comp)
		c->pipe0.refs--;
	if (comp == c->pipe1.comp)
		c->pipe1.refs--;
	mutex_unlock(&c->start_mutex);
	return 0;
}
EXPORT_SYMBOL_GPL(most_stop_channel);

/**
 * most_register_component - registers a driver component with the core
 * @comp: driver component
 */
int most_register_component(struct most_component *comp)
{
	if (!comp) {
		pr_err("Bad component\n");
		return -EINVAL;
	}
	list_add_tail(&comp->list, &comp_list);
	return 0;
}
EXPORT_SYMBOL_GPL(most_register_component);

static int disconnect_channels(struct device *dev, void *data)
{
	struct most_interface *iface;
	struct most_channel *c, *tmp;
	struct most_component *comp = data;

	iface = dev_get_drvdata(dev);
	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
		if (c->pipe0.comp == comp || c->pipe1.comp == comp)
			comp->disconnect_channel(c->iface, c->channel_id);
		if (c->pipe0.comp == comp)
			c->pipe0.comp = NULL;
		if (c->pipe1.comp == comp)
			c->pipe1.comp = NULL;
	}
	return 0;
}

/**
 * most_deregister_component - deregisters a driver component with the core
 * @comp: driver component
 */
int most_deregister_component(struct most_component *comp)
{
	if (!comp) {
		pr_err("Bad component\n");
		return -EINVAL;
	}

	bus_for_each_dev(&mostbus, NULL, comp, disconnect_channels);
	list_del(&comp->list);
	return 0;
}
EXPORT_SYMBOL_GPL(most_deregister_component);

static void release_channel(struct device *dev)
{
	struct most_channel *c = to_channel(dev);

	kfree(c);
}

/**
 * most_register_interface - registers an interface with core
 * @iface: device interface
 *
 * Allocates and initializes a new interface instance and all of its channels.
 * Returns a pointer to kobject or an error pointer.
 */
int most_register_interface(struct most_interface *iface)
{
	unsigned int i;
	int id;
	struct most_channel *c;

	if (!iface || !iface->enqueue || !iface->configure ||
	    !iface->poison_channel || (iface->num_channels > MAX_CHANNELS))
		return -EINVAL;

	id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
	if (id < 0) {
		dev_err(iface->dev, "Failed to allocate device ID\n");
		return id;
	}

	iface->p = kzalloc(sizeof(*iface->p), GFP_KERNEL);
	if (!iface->p) {
		ida_simple_remove(&mdev_id, id);
		return -ENOMEM;
	}

	INIT_LIST_HEAD(&iface->p->channel_list);
	iface->p->dev_id = id;
	strscpy(iface->p->name, iface->description, sizeof(iface->p->name));
	iface->dev->bus = &mostbus;
	iface->dev->groups = interface_attr_groups;
	dev_set_drvdata(iface->dev, iface);
	if (device_register(iface->dev)) {
		dev_err(iface->dev, "Failed to register interface device\n");
		kfree(iface->p);
		put_device(iface->dev);
		ida_simple_remove(&mdev_id, id);
		return -ENOMEM;
	}

	for (i = 0; i < iface->num_channels; i++) {
		const char *name_suffix = iface->channel_vector[i].name_suffix;

		c = kzalloc(sizeof(*c), GFP_KERNEL);
		if (!c)
			goto err_free_resources;
		if (!name_suffix)
			snprintf(c->name, STRING_SIZE, "ch%d", i);
		else
			snprintf(c->name, STRING_SIZE, "%s", name_suffix);
		c->dev.init_name = c->name;
		c->dev.parent = iface->dev;
		c->dev.groups = channel_attr_groups;
		c->dev.release = release_channel;
		iface->p->channel[i] = c;
		c->is_starving = 0;
		c->iface = iface;
		c->channel_id = i;
		c->keep_mbo = false;
		c->enqueue_halt = false;
		c->is_poisoned = false;
		c->cfg.direction = 0;
		c->cfg.data_type = 0;
		c->cfg.num_buffers = 0;
		c->cfg.buffer_size = 0;
		c->cfg.subbuffer_size = 0;
		c->cfg.packets_per_xact = 0;
		spin_lock_init(&c->fifo_lock);
		INIT_LIST_HEAD(&c->fifo);
		INIT_LIST_HEAD(&c->trash_fifo);
		INIT_LIST_HEAD(&c->halt_fifo);
		init_completion(&c->cleanup);
		atomic_set(&c->mbo_ref, 0);
		mutex_init(&c->start_mutex);
		mutex_init(&c->nq_mutex);
		list_add_tail(&c->list, &iface->p->channel_list);
		if (device_register(&c->dev)) {
			dev_err(&c->dev, "Failed to register channel device\n");
			goto err_free_most_channel;
		}
	}
	most_interface_register_notify(iface->description);
	return 0;

err_free_most_channel:
	put_device(&c->dev);

err_free_resources:
	while (i > 0) {
		c = iface->p->channel[--i];
		device_unregister(&c->dev);
	}
	kfree(iface->p);
	device_unregister(iface->dev);
	ida_simple_remove(&mdev_id, id);
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(most_register_interface);

/**
 * most_deregister_interface - deregisters an interface with core
 * @iface: device interface
 *
 * Before removing an interface instance from the list, all running
 * channels are stopped and poisoned.
 */
void most_deregister_interface(struct most_interface *iface)
{
	int i;
	struct most_channel *c;

	for (i = 0; i < iface->num_channels; i++) {
		c = iface->p->channel[i];
		if (c->pipe0.comp)
			c->pipe0.comp->disconnect_channel(c->iface,
							c->channel_id);
		if (c->pipe1.comp)
			c->pipe1.comp->disconnect_channel(c->iface,
							c->channel_id);
		c->pipe0.comp = NULL;
		c->pipe1.comp = NULL;
		list_del(&c->list);
		device_unregister(&c->dev);
	}

	ida_simple_remove(&mdev_id, iface->p->dev_id);
	kfree(iface->p);
	device_unregister(iface->dev);
}
EXPORT_SYMBOL_GPL(most_deregister_interface);

/**
 * most_stop_enqueue - prevents core from enqueueing MBOs
 * @iface: pointer to interface
 * @id: channel id
 *
 * This is called by an HDM that _cannot_ attend to its duties and
 * is imminent to get run over by the core. The core is not going to
 * enqueue any further packets unless the flagging HDM calls
 * most_resume enqueue().
 */
void most_stop_enqueue(struct most_interface *iface, int id)
{
	struct most_channel *c = iface->p->channel[id];

	if (!c)
		return;

	mutex_lock(&c->nq_mutex);
	c->enqueue_halt = true;
	mutex_unlock(&c->nq_mutex);
}
EXPORT_SYMBOL_GPL(most_stop_enqueue);

/**
 * most_resume_enqueue - allow core to enqueue MBOs again
 * @iface: pointer to interface
 * @id: channel id
 *
 * This clears the enqueue halt flag and enqueues all MBOs currently
 * sitting in the wait fifo.
 */
void most_resume_enqueue(struct most_interface *iface, int id)
{
	struct most_channel *c = iface->p->channel[id];

	if (!c)
		return;

	mutex_lock(&c->nq_mutex);
	c->enqueue_halt = false;
	mutex_unlock(&c->nq_mutex);

	wake_up_interruptible(&c->hdm_fifo_wq);
}
EXPORT_SYMBOL_GPL(most_resume_enqueue);

static int __init most_init(void)
{
	int err;

	INIT_LIST_HEAD(&comp_list);
	ida_init(&mdev_id);

	err = bus_register(&mostbus);
	if (err) {
		pr_err("Failed to register most bus\n");
		return err;
	}
	err = driver_register(&mostbus_driver);
	if (err) {
		pr_err("Failed to register core driver\n");
		goto err_unregister_bus;
	}
	configfs_init();
	return 0;

err_unregister_bus:
	bus_unregister(&mostbus);
	return err;
}

static void __exit most_exit(void)
{
	driver_unregister(&mostbus_driver);
	bus_unregister(&mostbus);
	ida_destroy(&mdev_id);
}

subsys_initcall(most_init);
module_exit(most_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");