aboutsummaryrefslogtreecommitdiffstats
path: root/recipes-kernel/hdm-usb/files/hdm_usb.c
blob: 41690f801fb8c6af9ebf636da98b4128241c9970 (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
/*
 * hdm_usb.c - Hardware dependent module for USB
 *
 * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * This file is licensed under GPLv2.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/usb.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/sysfs.h>
#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/uaccess.h>
#include "mostcore.h"
#include "networking.h"

#define USB_MTU			512
#define NO_ISOCHRONOUS_URB	0
#define AV_PACKETS_PER_XACT	2
#define BUF_CHAIN_SIZE		0xFFFF
#define MAX_NUM_ENDPOINTS	30
#define MAX_SUFFIX_LEN		10
#define MAX_STRING_LEN		80
#define MAX_BUF_SIZE		0xFFFF
#define CEILING(x, y)		(((x) + (y) - 1) / (y))

#define USB_VENDOR_ID_SMSC	0x0424  /* VID: SMSC */
#define USB_DEV_ID_BRDG		0xC001  /* PID: USB Bridge */
#define USB_DEV_ID_INIC		0xCF18  /* PID: USB INIC */
#define HW_RESYNC		0x0000
/* DRCI Addresses */
#define DRCI_REG_NI_STATE	0x0100
#define DRCI_REG_PACKET_BW	0x0101
#define DRCI_REG_NODE_ADDR	0x0102
#define DRCI_REG_NODE_POS	0x0103
#define DRCI_REG_MEP_FILTER	0x0140
#define DRCI_REG_HASH_TBL0	0x0141
#define DRCI_REG_HASH_TBL1	0x0142
#define DRCI_REG_HASH_TBL2	0x0143
#define DRCI_REG_HASH_TBL3	0x0144
#define DRCI_REG_HW_ADDR_HI	0x0145
#define DRCI_REG_HW_ADDR_MI	0x0146
#define DRCI_REG_HW_ADDR_LO	0x0147
#define DRCI_REG_BASE		0x1100
#define DRCI_COMMAND		0x02
#define DRCI_READ_REQ		0xA0
#define DRCI_WRITE_REQ		0xA1

/**
 * struct buf_anchor - used to create a list of pending URBs
 * @urb: pointer to USB request block
 * @clear_work_obj:
 * @list: linked list
 * @urb_completion:
 */
struct buf_anchor {
	struct urb *urb;
	struct work_struct clear_work_obj;
	struct list_head list;
	struct completion urb_compl;
};

#define to_buf_anchor(w) container_of(w, struct buf_anchor, clear_work_obj)

/**
 * struct most_dci_obj - Direct Communication Interface
 * @kobj:position in sysfs
 * @usb_device: pointer to the usb device
 */
struct most_dci_obj {
	struct kobject kobj;
	struct usb_device *usb_device;
};

#define to_dci_obj(p) container_of(p, struct most_dci_obj, kobj)

/**
 * struct most_dev - holds all usb interface specific stuff
 * @parent: parent object in sysfs
 * @usb_device: pointer to usb device
 * @iface: hardware interface
 * @cap: channel capabilities
 * @conf: channel configuration
 * @dci: direct communication interface of hardware
 * @hw_addr: MAC address of hardware
 * @ep_address: endpoint address table
 * @link_stat: link status of hardware
 * @description: device description
 * @suffix: suffix for channel name
 * @anchor_list_lock: locks list access
 * @padding_active: indicates channel uses padding
 * @is_channel_healthy: health status table of each channel
 * @anchor_list: list of anchored items
 * @io_mutex: synchronize I/O with disconnect
 * @link_stat_timer: timer for link status reports
 * @poll_work_obj: work for polling link status
 */
struct most_dev {
	struct kobject *parent;
	struct usb_device *usb_device;
	struct most_interface iface;
	struct most_channel_capability *cap;
	struct most_channel_config *conf;
	struct most_dci_obj *dci;
	u8 hw_addr[6];
	u8 *ep_address;
	u16 link_stat;
	char description[MAX_STRING_LEN];
	char suffix[MAX_NUM_ENDPOINTS][MAX_SUFFIX_LEN];
	spinlock_t anchor_list_lock[MAX_NUM_ENDPOINTS];
	bool padding_active[MAX_NUM_ENDPOINTS];
	bool is_channel_healthy[MAX_NUM_ENDPOINTS];
	struct list_head *anchor_list;
	struct mutex io_mutex;
	struct timer_list link_stat_timer;
	struct work_struct poll_work_obj;
};

#define to_mdev(d) container_of(d, struct most_dev, iface)
#define to_mdev_from_work(w) container_of(w, struct most_dev, poll_work_obj)

static struct workqueue_struct *schedule_usb_work;
static void wq_clear_halt(struct work_struct *wq_obj);
static void wq_netinfo(struct work_struct *wq_obj);

/**
 * drci_rd_reg - read a DCI register
 * @dev: usb device
 * @reg: register address
 * @buf: buffer to store data
 *
 * This is reads data from INIC's direct register communication interface
 */
static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
{
	int retval;
	u16 *dma_buf = kzalloc(sizeof(u16), GFP_KERNEL);
	u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;

	if (!dma_buf)
		return -ENOMEM;

	retval = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
				 DRCI_READ_REQ, req_type,
				 0x0000,
				 reg, dma_buf, sizeof(u16), 5 * HZ);
	*buf = le16_to_cpu(*dma_buf);
	kfree(dma_buf);

	return retval;
}

/**
 * drci_wr_reg - write a DCI register
 * @dev: usb device
 * @reg: register address
 * @data: data to write
 *
 * This is writes data to INIC's direct register communication interface
 */
static inline int drci_wr_reg(struct usb_device *dev, u16 reg, u16 data)
{
	return usb_control_msg(dev,
			       usb_sndctrlpipe(dev, 0),
			       DRCI_WRITE_REQ,
			       USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			       data,
			       reg,
			       NULL,
			       0,
			       5 * HZ);
}

/**
 * free_anchored_buffers - free device's anchored items
 * @mdev: the device
 * @channel: channel ID
 */
static void free_anchored_buffers(struct most_dev *mdev, unsigned int channel)
{
	struct mbo *mbo;
	struct buf_anchor *anchor, *tmp;
	unsigned long flags;

	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_for_each_entry_safe(anchor, tmp, &mdev->anchor_list[channel],
				 list) {
		struct urb *urb = anchor->urb;

		spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
		if (likely(urb)) {
			mbo = urb->context;
			if (!irqs_disabled()) {
				usb_kill_urb(urb);
			} else {
				usb_unlink_urb(urb);
				wait_for_completion(&anchor->urb_compl);
			}
			if ((mbo) && (mbo->complete)) {
				mbo->status = MBO_E_CLOSE;
				mbo->processed_length = 0;
				mbo->complete(mbo);
			}
			usb_free_urb(urb);
		}
		spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
		list_del(&anchor->list);
		kfree(anchor);
	}
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
}

/**
 * get_stream_frame_size - calculate frame size of current configuration
 * @cfg: channel configuration
 */
static unsigned int get_stream_frame_size(struct most_channel_config *cfg)
{
	unsigned int frame_size = 0;
	unsigned int sub_size = cfg->subbuffer_size;

	if (!sub_size) {
		pr_warn("Misconfig: Subbuffer size zero.\n");
		return frame_size;
	}
	switch (cfg->data_type) {
	case MOST_CH_ISOC_AVP:
		frame_size = AV_PACKETS_PER_XACT * sub_size;
		break;
	case MOST_CH_SYNC:
		if (cfg->packets_per_xact == 0) {
			pr_warn("Misconfig: Packets per XACT zero\n");
			frame_size = 0;
		} else if (cfg->packets_per_xact == 0xFF) {
			frame_size = (USB_MTU / sub_size) * sub_size;
		} else {
			frame_size = cfg->packets_per_xact * sub_size;
		}
		break;
	default:
		pr_warn("Query frame size of non-streaming channel\n");
		break;
	}
	return frame_size;
}

/**
 * hdm_poison_channel - mark buffers of this channel as invalid
 * @iface: pointer to the interface
 * @channel: channel ID
 *
 * This unlinks all URBs submitted to the HCD,
 * calls the associated completion function of the core and removes
 * them from the list.
 *
 * Returns 0 on success or error code otherwise.
 */
static int hdm_poison_channel(struct most_interface *iface, int channel)
{
	struct most_dev *mdev;

	mdev = to_mdev(iface);
	if (unlikely(!iface)) {
		dev_warn(&mdev->usb_device->dev, "Poison: Bad interface.\n");
		return -EIO;
	}
	if (unlikely((channel < 0) || (channel >= iface->num_channels))) {
		dev_warn(&mdev->usb_device->dev, "Channel ID out of range.\n");
		return -ECHRNG;
	}

	mdev->is_channel_healthy[channel] = false;

	mutex_lock(&mdev->io_mutex);
	free_anchored_buffers(mdev, channel);
	if (mdev->padding_active[channel])
		mdev->padding_active[channel] = false;

	if (mdev->conf[channel].data_type == MOST_CH_ASYNC) {
		del_timer_sync(&mdev->link_stat_timer);
		cancel_work_sync(&mdev->poll_work_obj);
	}
	mutex_unlock(&mdev->io_mutex);
	return 0;
}

/**
 * hdm_add_padding - add padding bytes
 * @mdev: most device
 * @channel: channel ID
 * @mbo: buffer object
 *
 * This inserts the INIC hardware specific padding bytes into a streaming
 * channel's buffer
 */
static int hdm_add_padding(struct most_dev *mdev, int channel, struct mbo *mbo)
{
	struct most_channel_config *conf = &mdev->conf[channel];
	unsigned int j, num_frames, frame_size;
	u16 rd_addr, wr_addr;

	frame_size = get_stream_frame_size(conf);
	if (!frame_size)
		return -EIO;
	num_frames = mbo->buffer_length / frame_size;

	if (num_frames < 1) {
		dev_err(&mdev->usb_device->dev,
			"Missed minimal transfer unit.\n");
		return -EIO;
	}

	for (j = 1; j < num_frames; j++) {
		wr_addr = (num_frames - j) * USB_MTU;
		rd_addr = (num_frames - j) * frame_size;
		memmove(mbo->virt_address + wr_addr,
			mbo->virt_address + rd_addr,
			frame_size);
	}
	mbo->buffer_length = num_frames * USB_MTU;
	return 0;
}

/**
 * hdm_remove_padding - remove padding bytes
 * @mdev: most device
 * @channel: channel ID
 * @mbo: buffer object
 *
 * This takes the INIC hardware specific padding bytes off a streaming
 * channel's buffer.
 */
static int hdm_remove_padding(struct most_dev *mdev, int channel,
			      struct mbo *mbo)
{
	unsigned int j, num_frames, frame_size;
	struct most_channel_config *const conf = &mdev->conf[channel];

	frame_size = get_stream_frame_size(conf);
	if (!frame_size)
		return -EIO;
	num_frames = mbo->processed_length / USB_MTU;

	for (j = 1; j < num_frames; j++)
		memmove(mbo->virt_address + frame_size * j,
			mbo->virt_address + USB_MTU * j,
			frame_size);

	mbo->processed_length = frame_size * num_frames;
	return 0;
}

/**
 * hdm_write_completion - completion function for submitted Tx URBs
 * @urb: the URB that has been completed
 *
 * This checks the status of the completed URB. In case the URB has been
 * unlinked before, it is immediately freed. On any other error the MBO
 * transfer flag is set. On success it frees allocated resources and calls
 * the completion function.
 *
 * Context: interrupt!
 */
static void hdm_write_completion(struct urb *urb)
{
	struct mbo *mbo;
	struct buf_anchor *anchor;
	struct most_dev *mdev;
	struct device *dev;
	unsigned int channel;
	unsigned long flags;

	mbo = urb->context;
	anchor = mbo->priv;
	mdev = to_mdev(mbo->ifp);
	channel = mbo->hdm_channel_id;
	dev = &mdev->usb_device->dev;

	if ((urb->status == -ENOENT) || (urb->status == -ECONNRESET) ||
	    (!mdev->is_channel_healthy[channel])) {
		complete(&anchor->urb_compl);
		return;
	}

	if (unlikely(urb->status && !(urb->status == -ENOENT ||
				      urb->status == -ECONNRESET ||
				      urb->status == -ESHUTDOWN))) {
		mbo->processed_length = 0;
		switch (urb->status) {
		case -EPIPE:
			dev_warn(dev, "Broken OUT pipe detected\n");
			most_stop_enqueue(&mdev->iface, channel);
			mbo->status = MBO_E_INVAL;
			usb_unlink_urb(urb);
			INIT_WORK(&anchor->clear_work_obj, wq_clear_halt);
			queue_work(schedule_usb_work, &anchor->clear_work_obj);
			return;
		case -ENODEV:
		case -EPROTO:
			mbo->status = MBO_E_CLOSE;
			break;
		default:
			mbo->status = MBO_E_INVAL;
			break;
		}
	} else {
		mbo->status = MBO_SUCCESS;
		mbo->processed_length = urb->actual_length;
	}

	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_del(&anchor->list);
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
	kfree(anchor);

	if (likely(mbo->complete))
		mbo->complete(mbo);
	usb_free_urb(urb);
}

/**
 * hdm_read_completion - completion function for submitted Rx URBs
 * @urb: the URB that has been completed
 *
 * This checks the status of the completed URB. In case the URB has been
 * unlinked before it is immediately freed. On any other error the MBO transfer
 * flag is set. On success it frees allocated resources, removes
 * padding bytes -if necessary- and calls the completion function.
 *
 * Context: interrupt!
 *
 * **************************************************************************
 *                   Error codes returned by in urb->status
 *                   or in iso_frame_desc[n].status (for ISO)
 * *************************************************************************
 *
 * USB device drivers may only test urb status values in completion handlers.
 * This is because otherwise there would be a race between HCDs updating
 * these values on one CPU, and device drivers testing them on another CPU.
 *
 * A transfer's actual_length may be positive even when an error has been
 * reported.  That's because transfers often involve several packets, so that
 * one or more packets could finish before an error stops further endpoint I/O.
 *
 * For isochronous URBs, the urb status value is non-zero only if the URB is
 * unlinked, the device is removed, the host controller is disabled or the total
 * transferred length is less than the requested length and the URB_SHORT_NOT_OK
 * flag is set.  Completion handlers for isochronous URBs should only see
 * urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
 * Individual frame descriptor status fields may report more status codes.
 *
 *
 * 0			Transfer completed successfully
 *
 * -ENOENT		URB was synchronously unlinked by usb_unlink_urb
 *
 * -EINPROGRESS		URB still pending, no results yet
 *			(That is, if drivers see this it's a bug.)
 *
 * -EPROTO (*, **)	a) bitstuff error
 *			b) no response packet received within the
 *			   prescribed bus turn-around time
 *			c) unknown USB error
 *
 * -EILSEQ (*, **)	a) CRC mismatch
 *			b) no response packet received within the
 *			   prescribed bus turn-around time
 *			c) unknown USB error
 *
 *			Note that often the controller hardware does not
 *			distinguish among cases a), b), and c), so a
 *			driver cannot tell whether there was a protocol
 *			error, a failure to respond (often caused by
 *			device disconnect), or some other fault.
 *
 * -ETIME (**)		No response packet received within the prescribed
 *			bus turn-around time.  This error may instead be
 *			reported as -EPROTO or -EILSEQ.
 *
 * -ETIMEDOUT		Synchronous USB message functions use this code
 *			to indicate timeout expired before the transfer
 *			completed, and no other error was reported by HC.
 *
 * -EPIPE (**)		Endpoint stalled.  For non-control endpoints,
 *			reset this status with usb_clear_halt().
 *
 * -ECOMM		During an IN transfer, the host controller
 *			received data from an endpoint faster than it
 *			could be written to system memory
 *
 * -ENOSR		During an OUT transfer, the host controller
 *			could not retrieve data from system memory fast
 *			enough to keep up with the USB data rate
 *
 * -EOVERFLOW (*)	The amount of data returned by the endpoint was
 *			greater than either the max packet size of the
 *			endpoint or the remaining buffer size.  "Babble".
 *
 * -EREMOTEIO		The data read from the endpoint did not fill the
 *			specified buffer, and URB_SHORT_NOT_OK was set in
 *			urb->transfer_flags.
 *
 * -ENODEV		Device was removed.  Often preceded by a burst of
 *			other errors, since the hub driver doesn't detect
 *			device removal events immediately.
 *
 * -EXDEV		ISO transfer only partially completed
 *			(only set in iso_frame_desc[n].status, not urb->status)
 *
 * -EINVAL		ISO madness, if this happens: Log off and go home
 *
 * -ECONNRESET		URB was asynchronously unlinked by usb_unlink_urb
 *
 * -ESHUTDOWN		The device or host controller has been disabled due
 *			to some problem that could not be worked around,
 *			such as a physical disconnect.
 *
 *
 * (*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate
 * hardware problems such as bad devices (including firmware) or cables.
 *
 * (**) This is also one of several codes that different kinds of host
 * controller use to indicate a transfer has failed because of device
 * disconnect.  In the interval before the hub driver starts disconnect
 * processing, devices may receive such fault reports for every request.
 *
 * See <https://www.kernel.org/doc/Documentation/usb/error-codes.txt>
 */
static void hdm_read_completion(struct urb *urb)
{
	struct mbo *mbo;
	struct buf_anchor *anchor;
	struct most_dev *mdev;
	struct device *dev;
	unsigned long flags;
	unsigned int channel;

	mbo = urb->context;
	anchor = mbo->priv;
	mdev = to_mdev(mbo->ifp);
	channel = mbo->hdm_channel_id;
	dev = &mdev->usb_device->dev;

	if ((urb->status == -ENOENT) || (urb->status == -ECONNRESET) ||
	    (!mdev->is_channel_healthy[channel])) {
		complete(&anchor->urb_compl);
		return;
	}

	if (unlikely(urb->status && !(urb->status == -ENOENT ||
				      urb->status == -ECONNRESET ||
				      urb->status == -ESHUTDOWN))) {
		mbo->processed_length = 0;
		switch (urb->status) {
		case -EPIPE:
			dev_warn(dev, "Broken IN pipe detected\n");
			mbo->status = MBO_E_INVAL;
			usb_unlink_urb(urb);
			INIT_WORK(&anchor->clear_work_obj, wq_clear_halt);
			queue_work(schedule_usb_work, &anchor->clear_work_obj);
			return;
		case -ENODEV:
		case -EPROTO:
			mbo->status = MBO_E_CLOSE;
			break;
		case -EOVERFLOW:
			dev_warn(dev, "Babble on IN pipe detected\n");
		default:
			mbo->status = MBO_E_INVAL;
			break;
		}
	} else {
		mbo->processed_length = urb->actual_length;
		if (!mdev->padding_active[channel]) {
			mbo->status = MBO_SUCCESS;
		} else {
			if (hdm_remove_padding(mdev, channel, mbo)) {
				mbo->processed_length = 0;
				mbo->status = MBO_E_INVAL;
			} else {
				mbo->status = MBO_SUCCESS;
			}
		}
	}
	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_del(&anchor->list);
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
	kfree(anchor);

	if (likely(mbo->complete))
		mbo->complete(mbo);
	usb_free_urb(urb);
}

/**
 * hdm_enqueue - receive a buffer to be used for data transfer
 * @iface: interface to enqueue to
 * @channel: ID of the channel
 * @mbo: pointer to the buffer object
 *
 * This allocates a new URB and fills it according to the channel
 * that is being used for transmission of data. Before the URB is
 * submitted it is stored in the private anchor list.
 *
 * Returns 0 on success. On any error the URB is freed and a error code
 * is returned.
 *
 * Context: Could in _some_ cases be interrupt!
 */
static int hdm_enqueue(struct most_interface *iface, int channel,
		       struct mbo *mbo)
{
	struct most_dev *mdev;
	struct buf_anchor *anchor;
	struct most_channel_config *conf;
	struct device *dev;
	int retval = 0;
	struct urb *urb;
	unsigned long flags;
	unsigned long length;
	void *virt_address;

	if (unlikely(!iface || !mbo))
		return -EIO;
	if (unlikely(iface->num_channels <= channel) || (channel < 0))
		return -ECHRNG;

	mdev = to_mdev(iface);
	conf = &mdev->conf[channel];
	dev = &mdev->usb_device->dev;

	if (!mdev->usb_device)
		return -ENODEV;

	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_ATOMIC);
	if (!urb) {
		dev_err(dev, "Failed to allocate URB\n");
		return -ENOMEM;
	}

	anchor = kzalloc(sizeof(*anchor), GFP_ATOMIC);
	if (!anchor) {
		retval = -ENOMEM;
		goto _error;
	}

	anchor->urb = urb;
	init_completion(&anchor->urb_compl);
	mbo->priv = anchor;

	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_add_tail(&anchor->list, &mdev->anchor_list[channel]);
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);

	if ((mdev->padding_active[channel]) &&
	    (conf->direction & MOST_CH_TX))
		if (hdm_add_padding(mdev, channel, mbo)) {
			retval = -EIO;
			goto _error_1;
		}

	urb->transfer_dma = mbo->bus_address;
	virt_address = mbo->virt_address;
	length = mbo->buffer_length;

	if (conf->direction & MOST_CH_TX) {
		usb_fill_bulk_urb(urb, mdev->usb_device,
				  usb_sndbulkpipe(mdev->usb_device,
						  mdev->ep_address[channel]),
				  virt_address,
				  length,
				  hdm_write_completion,
				  mbo);
		if (conf->data_type != MOST_CH_ISOC_AVP)
			urb->transfer_flags |= URB_ZERO_PACKET;
	} else {
		usb_fill_bulk_urb(urb, mdev->usb_device,
				  usb_rcvbulkpipe(mdev->usb_device,
						  mdev->ep_address[channel]),
				  virt_address,
				  length + conf->extra_len,
				  hdm_read_completion,
				  mbo);
	}
	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (retval) {
		dev_err(dev, "URB submit failed with error %d.\n", retval);
		goto _error_1;
	}
	return 0;

_error_1:
	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_del(&anchor->list);
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);
	kfree(anchor);
_error:
	usb_free_urb(urb);
	return retval;
}

/**
 * hdm_configure_channel - receive channel configuration from core
 * @iface: interface
 * @channel: channel ID
 * @conf: structure that holds the configuration information
 */
static int hdm_configure_channel(struct most_interface *iface, int channel,
				 struct most_channel_config *conf)
{
	unsigned int num_frames;
	unsigned int frame_size;
	unsigned int temp_size;
	unsigned int tail_space;
	struct most_dev *mdev;
	struct device *dev;

	mdev = to_mdev(iface);
	mdev->is_channel_healthy[channel] = true;
	dev = &mdev->usb_device->dev;

	if (unlikely(!iface || !conf)) {
		dev_err(dev, "Bad interface or config pointer.\n");
		return -EINVAL;
	}
	if (unlikely((channel < 0) || (channel >= iface->num_channels))) {
		dev_err(dev, "Channel ID out of range.\n");
		return -EINVAL;
	}
	if ((!conf->num_buffers) || (!conf->buffer_size)) {
		dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
		return -EINVAL;
	}

	if (!(conf->data_type == MOST_CH_SYNC) &&
	    !((conf->data_type == MOST_CH_ISOC_AVP) &&
	      (conf->packets_per_xact != 0xFF))) {
		mdev->padding_active[channel] = false;
		goto exit;
	}

	mdev->padding_active[channel] = true;
	temp_size = conf->buffer_size;

	frame_size = get_stream_frame_size(conf);
	if ((frame_size == 0) || (frame_size > USB_MTU)) {
		dev_warn(dev, "Misconfig: frame size wrong\n");
		return -EINVAL;
	}

	if (conf->buffer_size % frame_size) {
		u16 tmp_val;

		tmp_val = conf->buffer_size / frame_size;
		conf->buffer_size = tmp_val * frame_size;
		dev_notice(dev,
			   "Channel %d - rounding buffer size to %d bytes, channel config says %d bytes\n",
			   channel,
			   conf->buffer_size,
			   temp_size);
	}

	num_frames = conf->buffer_size / frame_size;
	tail_space = num_frames * (USB_MTU - frame_size);
	temp_size += tail_space;

	/* calculate extra length to comply w/ HW padding */
	conf->extra_len = (CEILING(temp_size, USB_MTU) * USB_MTU)
			  - conf->buffer_size;
exit:
	mdev->conf[channel] = *conf;
	return 0;
}

/**
 * hdm_update_netinfo - retrieve latest networking information
 * @mdev: device interface
 *
 * This triggers the USB vendor requests to read the hardware address and
 * the current link status of the attached device.
 */
static int hdm_update_netinfo(struct most_dev *mdev)
{
	struct usb_device *usb_device = mdev->usb_device;
	struct device *dev = &usb_device->dev;
	u16 hi, mi, lo, link;

	if (!is_valid_ether_addr(mdev->hw_addr)) {
		if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_HI, &hi) < 0) {
			dev_err(dev, "Vendor request \"hw_addr_hi\" failed\n");
			return -1;
		}

		if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_MI, &mi) < 0) {
			dev_err(dev, "Vendor request \"hw_addr_mid\" failed\n");
			return -1;
		}

		if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_LO, &lo) < 0) {
			dev_err(dev, "Vendor request \"hw_addr_low\" failed\n");
			return -1;
		}

		mutex_lock(&mdev->io_mutex);
		mdev->hw_addr[0] = hi >> 8;
		mdev->hw_addr[1] = hi;
		mdev->hw_addr[2] = mi >> 8;
		mdev->hw_addr[3] = mi;
		mdev->hw_addr[4] = lo >> 8;
		mdev->hw_addr[5] = lo;
		mutex_unlock(&mdev->io_mutex);
	}

	if (drci_rd_reg(usb_device, DRCI_REG_NI_STATE, &link) < 0) {
		dev_err(dev, "Vendor request \"link status\" failed\n");
		return -1;
	}

	mutex_lock(&mdev->io_mutex);
	mdev->link_stat = link;
	mutex_unlock(&mdev->io_mutex);
	return 0;
}

/**
 * hdm_request_netinfo - request network information
 * @iface: pointer to interface
 * @channel: channel ID
 *
 * This is used as trigger to set up the link status timer that
 * polls for the NI state of the INIC every 2 seconds.
 *
 */
static void hdm_request_netinfo(struct most_interface *iface, int channel)
{
	struct most_dev *mdev;

	BUG_ON(!iface);
	mdev = to_mdev(iface);
	mdev->link_stat_timer.expires = jiffies + HZ;
	mod_timer(&mdev->link_stat_timer, mdev->link_stat_timer.expires);
}

/**
 * link_stat_timer_handler - add work to link_stat work queue
 * @data: pointer to USB device instance
 *
 * The handler runs in interrupt context. That's why we need to defer the
 * tasks to a work queue.
 */
static void link_stat_timer_handler(unsigned long data)
{
	struct most_dev *mdev = (struct most_dev *)data;

	queue_work(schedule_usb_work, &mdev->poll_work_obj);
	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
	add_timer(&mdev->link_stat_timer);
}

/**
 * wq_netinfo - work queue function
 * @wq_obj: object that holds data for our deferred work to do
 *
 * This retrieves the network interface status of the USB INIC
 * and compares it with the current status. If the status has
 * changed, it updates the status of the core.
 */
static void wq_netinfo(struct work_struct *wq_obj)
{
	struct most_dev *mdev;
	int i, prev_link_stat;
	u8 prev_hw_addr[6];

	mdev = to_mdev_from_work(wq_obj);
	prev_link_stat = mdev->link_stat;

	for (i = 0; i < 6; i++)
		prev_hw_addr[i] = mdev->hw_addr[i];

	if (hdm_update_netinfo(mdev) < 0)
		return;
	if ((prev_link_stat != mdev->link_stat) ||
	    (prev_hw_addr[0] != mdev->hw_addr[0]) ||
	    (prev_hw_addr[1] != mdev->hw_addr[1]) ||
	    (prev_hw_addr[2] != mdev->hw_addr[2]) ||
	    (prev_hw_addr[3] != mdev->hw_addr[3]) ||
	    (prev_hw_addr[4] != mdev->hw_addr[4]) ||
	    (prev_hw_addr[5] != mdev->hw_addr[5]))
		most_deliver_netinfo(&mdev->iface, mdev->link_stat,
				     &mdev->hw_addr[0]);
}

/**
 * wq_clear_halt - work queue function
 * @wq_obj: work_struct object to execute
 *
 * This sends a clear_halt to the given USB pipe.
 */
static void wq_clear_halt(struct work_struct *wq_obj)
{
	struct buf_anchor *anchor;
	struct most_dev *mdev;
	struct mbo *mbo;
	struct urb *urb;
	unsigned int channel;
	unsigned long flags;

	anchor = to_buf_anchor(wq_obj);
	urb = anchor->urb;
	mbo = urb->context;
	mdev = to_mdev(mbo->ifp);
	channel = mbo->hdm_channel_id;

	if (usb_clear_halt(urb->dev, urb->pipe))
		dev_warn(&mdev->usb_device->dev, "Failed to reset endpoint.\n");

	usb_free_urb(urb);
	spin_lock_irqsave(&mdev->anchor_list_lock[channel], flags);
	list_del(&anchor->list);
	spin_unlock_irqrestore(&mdev->anchor_list_lock[channel], flags);

	if (likely(mbo->complete))
		mbo->complete(mbo);
	if (mdev->conf[channel].direction & MOST_CH_TX)
		most_resume_enqueue(&mdev->iface, channel);

	kfree(anchor);
}

/**
 * hdm_usb_fops - file operation table for USB driver
 */
static const struct file_operations hdm_usb_fops = {
	.owner = THIS_MODULE,
};

/**
 * usb_device_id - ID table for HCD device probing
 */
static struct usb_device_id usbid[] = {
	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_BRDG), },
	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_INIC), },
	{ } /* Terminating entry */
};

#define MOST_DCI_RO_ATTR(_name) \
	struct most_dci_attribute most_dci_attr_##_name = \
		__ATTR(_name, S_IRUGO, show_value, NULL)

#define MOST_DCI_ATTR(_name) \
	struct most_dci_attribute most_dci_attr_##_name = \
		__ATTR(_name, S_IRUGO | S_IWUSR, show_value, store_value)

/**
 * struct most_dci_attribute - to access the attributes of a dci object
 * @attr: attributes of a dci object
 * @show: pointer to the show function
 * @store: pointer to the store function
 */
struct most_dci_attribute {
	struct attribute attr;
	ssize_t (*show)(struct most_dci_obj *d,
			struct most_dci_attribute *attr,
			char *buf);
	ssize_t (*store)(struct most_dci_obj *d,
			 struct most_dci_attribute *attr,
			 const char *buf,
			 size_t count);
};

#define to_dci_attr(a) container_of(a, struct most_dci_attribute, attr)

/**
 * dci_attr_show - show function for dci object
 * @kobj: pointer to kobject
 * @attr: pointer to attribute struct
 * @buf: buffer
 */
static ssize_t dci_attr_show(struct kobject *kobj, struct attribute *attr,
			     char *buf)
{
	struct most_dci_attribute *dci_attr = to_dci_attr(attr);
	struct most_dci_obj *dci_obj = to_dci_obj(kobj);

	if (!dci_attr->show)
		return -EIO;

	return dci_attr->show(dci_obj, dci_attr, buf);
}

/**
 * dci_attr_store - store function for dci object
 * @kobj: pointer to kobject
 * @attr: pointer to attribute struct
 * @buf: buffer
 * @len: length of buffer
 */
static ssize_t dci_attr_store(struct kobject *kobj,
			      struct attribute *attr,
			      const char *buf,
			      size_t len)
{
	struct most_dci_attribute *dci_attr = to_dci_attr(attr);
	struct most_dci_obj *dci_obj = to_dci_obj(kobj);

	if (!dci_attr->store)
		return -EIO;

	return dci_attr->store(dci_obj, dci_attr, buf, len);
}

static const struct sysfs_ops most_dci_sysfs_ops = {
	.show = dci_attr_show,
	.store = dci_attr_store,
};

/**
 * most_dci_release - release function for dci object
 * @kobj: pointer to kobject
 *
 * This frees the memory allocated for the dci object
 */
static void most_dci_release(struct kobject *kobj)
{
	struct most_dci_obj *dci_obj = to_dci_obj(kobj);

	kfree(dci_obj);
}

static ssize_t show_value(struct most_dci_obj *dci_obj,
			  struct most_dci_attribute *attr, char *buf)
{
	u16 tmp_val;
	u16 reg_addr;
	int err;

	if (!strcmp(attr->attr.name, "ni_state"))
		reg_addr = DRCI_REG_NI_STATE;
	else if (!strcmp(attr->attr.name, "packet_bandwidth"))
		reg_addr = DRCI_REG_PACKET_BW;
	else if (!strcmp(attr->attr.name, "node_address"))
		reg_addr = DRCI_REG_NODE_ADDR;
	else if (!strcmp(attr->attr.name, "node_position"))
		reg_addr = DRCI_REG_NODE_POS;
	else if (!strcmp(attr->attr.name, "mep_filter"))
		reg_addr = DRCI_REG_MEP_FILTER;
	else if (!strcmp(attr->attr.name, "mep_hash0"))
		reg_addr = DRCI_REG_HASH_TBL0;
	else if (!strcmp(attr->attr.name, "mep_hash1"))
		reg_addr = DRCI_REG_HASH_TBL1;
	else if (!strcmp(attr->attr.name, "mep_hash2"))
		reg_addr = DRCI_REG_HASH_TBL2;
	else if (!strcmp(attr->attr.name, "mep_hash3"))
		reg_addr = DRCI_REG_HASH_TBL3;
	else if (!strcmp(attr->attr.name, "mep_eui48_hi"))
		reg_addr = DRCI_REG_HW_ADDR_HI;
	else if (!strcmp(attr->attr.name, "mep_eui48_mi"))
		reg_addr = DRCI_REG_HW_ADDR_MI;
	else if (!strcmp(attr->attr.name, "mep_eui48_lo"))
		reg_addr = DRCI_REG_HW_ADDR_LO;
	else
		return -EIO;

	err = drci_rd_reg(dci_obj->usb_device, reg_addr, &tmp_val);
	if (err < 0)
		return err;

	return snprintf(buf, PAGE_SIZE, "%04x\n", tmp_val);
}

static ssize_t store_value(struct most_dci_obj *dci_obj,
			   struct most_dci_attribute *attr,
			   const char *buf, size_t count)
{
	u16 val;
	u16 reg_addr;
	int err;

	if (!strcmp(attr->attr.name, "mep_filter"))
		reg_addr = DRCI_REG_MEP_FILTER;
	else if (!strcmp(attr->attr.name, "mep_hash0"))
		reg_addr = DRCI_REG_HASH_TBL0;
	else if (!strcmp(attr->attr.name, "mep_hash1"))
		reg_addr = DRCI_REG_HASH_TBL1;
	else if (!strcmp(attr->attr.name, "mep_hash2"))
		reg_addr = DRCI_REG_HASH_TBL2;
	else if (!strcmp(attr->attr.name, "mep_hash3"))
		reg_addr = DRCI_REG_HASH_TBL3;
	else if (!strcmp(attr->attr.name, "mep_eui48_hi"))
		reg_addr = DRCI_REG_HW_ADDR_HI;
	else if (!strcmp(attr->attr.name, "mep_eui48_mi"))
		reg_addr = DRCI_REG_HW_ADDR_MI;
	else if (!strcmp(attr->attr.name, "mep_eui48_lo"))
		reg_addr = DRCI_REG_HW_ADDR_LO;
	else
		return -EIO;

	err = kstrtou16(buf, 16, &val);
	if (err)
		return err;

	err = drci_wr_reg(dci_obj->usb_device, reg_addr, val);
	if (err < 0)
		return err;

	return count;
}

static MOST_DCI_RO_ATTR(ni_state);
static MOST_DCI_RO_ATTR(packet_bandwidth);
static MOST_DCI_RO_ATTR(node_address);
static MOST_DCI_RO_ATTR(node_position);
static MOST_DCI_ATTR(mep_filter);
static MOST_DCI_ATTR(mep_hash0);
static MOST_DCI_ATTR(mep_hash1);
static MOST_DCI_ATTR(mep_hash2);
static MOST_DCI_ATTR(mep_hash3);
static MOST_DCI_ATTR(mep_eui48_hi);
static MOST_DCI_ATTR(mep_eui48_mi);
static MOST_DCI_ATTR(mep_eui48_lo);

/**
 * most_dci_def_attrs - array of default attribute files of the dci object
 */
static struct attribute *most_dci_def_attrs[] = {
	&most_dci_attr_ni_state.attr,
	&most_dci_attr_packet_bandwidth.attr,
	&most_dci_attr_node_address.attr,
	&most_dci_attr_node_position.attr,
	&most_dci_attr_mep_filter.attr,
	&most_dci_attr_mep_hash0.attr,
	&most_dci_attr_mep_hash1.attr,
	&most_dci_attr_mep_hash2.attr,
	&most_dci_attr_mep_hash3.attr,
	&most_dci_attr_mep_eui48_hi.attr,
	&most_dci_attr_mep_eui48_mi.attr,
	&most_dci_attr_mep_eui48_lo.attr,
	NULL,
};

/**
 * DCI ktype
 */
static struct kobj_type most_dci_ktype = {
	.sysfs_ops = &most_dci_sysfs_ops,
	.release = most_dci_release,
	.default_attrs = most_dci_def_attrs,
};

/**
 * create_most_dci_obj - allocates a dci object
 * @parent: parent kobject
 *
 * This creates a dci object and registers it with sysfs.
 * Returns a pointer to the object or NULL when something went wrong.
 */
static struct
most_dci_obj *create_most_dci_obj(struct kobject *parent)
{
	struct most_dci_obj *most_dci;
	int retval;

	most_dci = kzalloc(sizeof(*most_dci), GFP_KERNEL);
	if (!most_dci)
		return NULL;

	retval = kobject_init_and_add(&most_dci->kobj, &most_dci_ktype, parent,
				      "dci");
	if (retval) {
		kobject_put(&most_dci->kobj);
		return NULL;
	}
	return most_dci;
}

/**
 * destroy_most_dci_obj - DCI object release function
 * @p: pointer to dci object
 */
static void destroy_most_dci_obj(struct most_dci_obj *p)
{
	kobject_put(&p->kobj);
}

/**
 * hdm_probe - probe function of USB device driver
 * @interface: Interface of the attached USB device
 * @id: Pointer to the USB ID table.
 *
 * This allocates and initializes the device instance, adds the new
 * entry to the internal list, scans the USB descriptors and registers
 * the interface with the core.
 * Additionally, the DCI objects are created and the hardware is sync'd.
 *
 * Return 0 on success. In case of an error a negative number is returned.
 */
static int
hdm_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
	unsigned int i;
	unsigned int num_endpoints;
	struct most_channel_capability *tmp_cap;
	struct most_dev *mdev;
	struct usb_device *usb_dev;
	struct device *dev;
	struct usb_host_interface *usb_iface_desc;
	struct usb_endpoint_descriptor *ep_desc;
	int ret = 0;
	int err;

	usb_iface_desc = interface->cur_altsetting;
	usb_dev = interface_to_usbdev(interface);
	dev = &usb_dev->dev;
	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
	if (!mdev)
		goto exit_ENOMEM;

	usb_set_intfdata(interface, mdev);
	num_endpoints = usb_iface_desc->desc.bNumEndpoints;
	mutex_init(&mdev->io_mutex);
	INIT_WORK(&mdev->poll_work_obj, wq_netinfo);
	setup_timer(&mdev->link_stat_timer, link_stat_timer_handler,
		    (unsigned long)mdev);

	mdev->usb_device = usb_dev;
	mdev->link_stat_timer.expires = jiffies + (2 * HZ);

	mdev->iface.mod = hdm_usb_fops.owner;
	mdev->iface.interface = ITYPE_USB;
	mdev->iface.configure = hdm_configure_channel;
	mdev->iface.request_netinfo = hdm_request_netinfo;
	mdev->iface.enqueue = hdm_enqueue;
	mdev->iface.poison_channel = hdm_poison_channel;
	mdev->iface.description = mdev->description;
	mdev->iface.num_channels = num_endpoints;

	snprintf(mdev->description, sizeof(mdev->description),
		 "usb_device %d-%s:%d.%d",
		 usb_dev->bus->busnum,
		 usb_dev->devpath,
		 usb_dev->config->desc.bConfigurationValue,
		 usb_iface_desc->desc.bInterfaceNumber);

	mdev->conf = kcalloc(num_endpoints, sizeof(*mdev->conf), GFP_KERNEL);
	if (!mdev->conf)
		goto exit_free;

	mdev->cap = kcalloc(num_endpoints, sizeof(*mdev->cap), GFP_KERNEL);
	if (!mdev->cap)
		goto exit_free1;

	mdev->iface.channel_vector = mdev->cap;
	mdev->iface.priv = NULL;

	mdev->ep_address =
		kcalloc(num_endpoints, sizeof(*mdev->ep_address), GFP_KERNEL);
	if (!mdev->ep_address)
		goto exit_free2;

	mdev->anchor_list =
		kcalloc(num_endpoints, sizeof(*mdev->anchor_list), GFP_KERNEL);
	if (!mdev->anchor_list)
		goto exit_free3;

	tmp_cap = mdev->cap;
	for (i = 0; i < num_endpoints; i++) {
		ep_desc = &usb_iface_desc->endpoint[i].desc;
		mdev->ep_address[i] = ep_desc->bEndpointAddress;
		mdev->padding_active[i] = false;
		mdev->is_channel_healthy[i] = true;

		snprintf(&mdev->suffix[i][0], MAX_SUFFIX_LEN, "ep%02x",
			 mdev->ep_address[i]);

		tmp_cap->name_suffix = &mdev->suffix[i][0];
		tmp_cap->buffer_size_packet = MAX_BUF_SIZE;
		tmp_cap->buffer_size_streaming = MAX_BUF_SIZE;
		tmp_cap->num_buffers_packet = BUF_CHAIN_SIZE;
		tmp_cap->num_buffers_streaming = BUF_CHAIN_SIZE;
		tmp_cap->data_type = MOST_CH_CONTROL | MOST_CH_ASYNC |
				     MOST_CH_ISOC_AVP | MOST_CH_SYNC;
		if (ep_desc->bEndpointAddress & USB_DIR_IN)
			tmp_cap->direction = MOST_CH_RX;
		else
			tmp_cap->direction = MOST_CH_TX;
		tmp_cap++;
		INIT_LIST_HEAD(&mdev->anchor_list[i]);
		spin_lock_init(&mdev->anchor_list_lock[i]);
		err = drci_wr_reg(usb_dev,
				  DRCI_REG_BASE + DRCI_COMMAND +
				  ep_desc->bEndpointAddress * 16,
				  1);
		if (err < 0)
			pr_warn("DCI Sync for EP %02x failed",
				ep_desc->bEndpointAddress);
	}
	dev_notice(dev, "claimed gadget: Vendor=%4.4x ProdID=%4.4x Bus=%02x Device=%02x\n",
		   le16_to_cpu(usb_dev->descriptor.idVendor),
		   le16_to_cpu(usb_dev->descriptor.idProduct),
		   usb_dev->bus->busnum,
		   usb_dev->devnum);

	dev_notice(dev, "device path: /sys/bus/usb/devices/%d-%s:%d.%d\n",
		   usb_dev->bus->busnum,
		   usb_dev->devpath,
		   usb_dev->config->desc.bConfigurationValue,
		   usb_iface_desc->desc.bInterfaceNumber);

	mdev->parent = most_register_interface(&mdev->iface);
	if (IS_ERR(mdev->parent)) {
		ret = PTR_ERR(mdev->parent);
		goto exit_free4;
	}

	mutex_lock(&mdev->io_mutex);
	if (le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_INIC) {
		/* this increments the reference count of the instance
		 * object of the core
		 */
		mdev->dci = create_most_dci_obj(mdev->parent);
		if (!mdev->dci) {
			mutex_unlock(&mdev->io_mutex);
			most_deregister_interface(&mdev->iface);
			ret = -ENOMEM;
			goto exit_free4;
		}

		kobject_uevent(&mdev->dci->kobj, KOBJ_ADD);
		mdev->dci->usb_device = mdev->usb_device;
	}
	mutex_unlock(&mdev->io_mutex);
	return 0;

exit_free4:
	kfree(mdev->anchor_list);
exit_free3:
	kfree(mdev->ep_address);
exit_free2:
	kfree(mdev->cap);
exit_free1:
	kfree(mdev->conf);
exit_free:
	kfree(mdev);
exit_ENOMEM:
	if (ret == 0 || ret == -ENOMEM) {
		ret = -ENOMEM;
		dev_err(dev, "out of memory\n");
	}
	return ret;
}

/**
 * hdm_disconnect - disconnect function of USB device driver
 * @interface: Interface of the attached USB device
 *
 * This deregisters the interface with the core, removes the kernel timer
 * and frees resources.
 *
 * Context: hub kernel thread
 */
static void hdm_disconnect(struct usb_interface *interface)
{
	struct most_dev *mdev;

	mdev = usb_get_intfdata(interface);
	mutex_lock(&mdev->io_mutex);
	usb_set_intfdata(interface, NULL);
	mdev->usb_device = NULL;
	mutex_unlock(&mdev->io_mutex);

	del_timer_sync(&mdev->link_stat_timer);
	cancel_work_sync(&mdev->poll_work_obj);

	destroy_most_dci_obj(mdev->dci);
	most_deregister_interface(&mdev->iface);

	kfree(mdev->anchor_list);
	kfree(mdev->cap);
	kfree(mdev->conf);
	kfree(mdev->ep_address);
	kfree(mdev);
}

static struct usb_driver hdm_usb = {
	.name = "hdm_usb",
	.id_table = usbid,
	.probe = hdm_probe,
	.disconnect = hdm_disconnect,
};

static int __init hdm_usb_init(void)
{
	pr_info("hdm_usb_init()\n");
	if (usb_register(&hdm_usb)) {
		pr_err("could not register hdm_usb driver\n");
		return -EIO;
	}
	schedule_usb_work = create_workqueue("hdmu_work");
	if (!schedule_usb_work) {
		pr_err("could not create workqueue\n");
		usb_deregister(&hdm_usb);
		return -ENOMEM;
	}
	return 0;
}

static void __exit hdm_usb_exit(void)
{
	pr_info("hdm_usb_exit()\n");
	destroy_workqueue(schedule_usb_work);
	usb_deregister(&hdm_usb);
}

module_init(hdm_usb_init);
module_exit(hdm_usb_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
MODULE_DESCRIPTION("HDM_4_USB");