summaryrefslogtreecommitdiffstats
path: root/drivers/misc/mic/scif/scif_nodeqp.c
blob: 6dfdae3452d609fd07c82cce24f933771a093a70 (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
/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2014 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * 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.
 *
 * Intel SCIF driver.
 *
 */
#include "../bus/scif_bus.h"
#include "scif_peer_bus.h"
#include "scif_main.h"
#include "scif_nodeqp.h"
#include "scif_map.h"

/*
 ************************************************************************
 * SCIF node Queue Pair (QP) setup flow:
 *
 * 1) SCIF driver gets probed with a scif_hw_dev via the scif_hw_bus
 * 2) scif_setup_qp(..) allocates the local qp and calls
 *	scif_setup_qp_connect(..) which allocates and maps the local
 *	buffer for the inbound QP
 * 3) The local node updates the device page with the DMA address of the QP
 * 4) A delayed work is scheduled (qp_dwork) which periodically reads if
 *	the peer node has updated its QP DMA address
 * 5) Once a valid non zero address is found in the QP DMA address field
 *	in the device page, the local node maps the remote node's QP,
 *	updates its outbound QP and sends a SCIF_INIT message to the peer
 * 6) The SCIF_INIT message is received by the peer node QP interrupt bottom
 *	half handler by calling scif_init(..)
 * 7) scif_init(..) registers a new SCIF peer node by calling
 *	scif_peer_register_device(..) which signifies the addition of a new
 *	SCIF node
 * 8) On the mgmt node, P2P network setup/teardown is initiated if all the
 *	remote nodes are online via scif_p2p_setup(..)
 * 9) For P2P setup, the host maps the remote nodes' aperture and memory
 *	bars and sends a SCIF_NODE_ADD message to both nodes
 * 10) As part of scif_nodeadd, both nodes set up their local inbound
 *	QPs and send a SCIF_NODE_ADD_ACK to the mgmt node
 * 11) As part of scif_node_add_ack(..) the mgmt node forwards the
 *	SCIF_NODE_ADD_ACK to the remote nodes
 * 12) As part of scif_node_add_ack(..) the remote nodes update their
 *	outbound QPs, make sure they can access memory on the remote node
 *	and then add a new SCIF peer node by calling
 *	scif_peer_register_device(..) which signifies the addition of a new
 *	SCIF node.
 * 13) The SCIF network is now established across all nodes.
 *
 ************************************************************************
 * SCIF node QP teardown flow (initiated by non mgmt node):
 *
 * 1) SCIF driver gets a remove callback with a scif_hw_dev via the scif_hw_bus
 * 2) The device page QP DMA address field is updated with 0x0
 * 3) A non mgmt node now cleans up all local data structures and sends a
 *	SCIF_EXIT message to the peer and waits for a SCIF_EXIT_ACK
 * 4) As part of scif_exit(..) handling scif_disconnect_node(..) is called
 * 5) scif_disconnect_node(..) sends a SCIF_NODE_REMOVE message to all the
 *	peers and waits for a SCIF_NODE_REMOVE_ACK
 * 6) As part of scif_node_remove(..) a remote node unregisters the peer
 *	node from the SCIF network and sends a SCIF_NODE_REMOVE_ACK
 * 7) When the mgmt node has received all the SCIF_NODE_REMOVE_ACKs
 *	it sends itself a node remove message whose handling cleans up local
 *	data structures and unregisters the peer node from the SCIF network
 * 8) The mgmt node sends a SCIF_EXIT_ACK
 * 9) Upon receipt of the SCIF_EXIT_ACK the node initiating the teardown
 *	completes the SCIF remove routine
 * 10) The SCIF network is now torn down for the node initiating the
 *	teardown sequence
 *
 ************************************************************************
 * SCIF node QP teardown flow (initiated by mgmt node):
 *
 * 1) SCIF driver gets a remove callback with a scif_hw_dev via the scif_hw_bus
 * 2) The device page QP DMA address field is updated with 0x0
 * 3) The mgmt node calls scif_disconnect_node(..)
 * 4) scif_disconnect_node(..) sends a SCIF_NODE_REMOVE message to all the peers
 *	and waits for a SCIF_NODE_REMOVE_ACK
 * 5) As part of scif_node_remove(..) a remote node unregisters the peer
 *	node from the SCIF network and sends a SCIF_NODE_REMOVE_ACK
 * 6) When the mgmt node has received all the SCIF_NODE_REMOVE_ACKs
 *	it unregisters the peer node from the SCIF network
 * 7) The mgmt node sends a SCIF_EXIT message and waits for a SCIF_EXIT_ACK.
 * 8) A non mgmt node upon receipt of a SCIF_EXIT message calls scif_stop(..)
 *	which would clean up local data structures for all SCIF nodes and
 *	then send a SCIF_EXIT_ACK back to the mgmt node
 * 9) Upon receipt of the SCIF_EXIT_ACK the the mgmt node sends itself a node
 *	remove message whose handling cleans up local data structures and
 *	destroys any P2P mappings.
 * 10) The SCIF hardware device for which a remove callback was received is now
 *	disconnected from the SCIF network.
 */
/*
 * Initializes "local" data structures for the QP. Allocates the QP
 * ring buffer (rb) and initializes the "in bound" queue.
 */
int scif_setup_qp_connect(struct scif_qp *qp, dma_addr_t *qp_offset,
			  int local_size, struct scif_dev *scifdev)
{
	void *local_q = NULL;
	int err = 0;
	u32 tmp_rd = 0;

	spin_lock_init(&qp->send_lock);
	spin_lock_init(&qp->recv_lock);

	local_q = kzalloc(local_size, GFP_KERNEL);
	if (!local_q) {
		err = -ENOMEM;
		return err;
	}
	err = scif_map_single(&qp->local_buf, local_q, scifdev, local_size);
	if (err)
		goto kfree;
	/*
	 * To setup the inbound_q, the buffer lives locally, the read pointer
	 * is remote and the write pointer is local.
	 */
	scif_rb_init(&qp->inbound_q,
		     &tmp_rd,
		     &qp->local_write,
		     local_q, get_count_order(local_size));
	/*
	 * The read pointer is NULL initially and it is unsafe to use the ring
	 * buffer til this changes!
	 */
	qp->inbound_q.read_ptr = NULL;
	err = scif_map_single(qp_offset, qp,
			      scifdev, sizeof(struct scif_qp));
	if (err)
		goto unmap;
	qp->local_qp = *qp_offset;
	return err;
unmap:
	scif_unmap_single(qp->local_buf, scifdev, local_size);
	qp->local_buf = 0;
kfree:
	kfree(local_q);
	return err;
}

/* When the other side has already done it's allocation, this is called */
int scif_setup_qp_accept(struct scif_qp *qp, dma_addr_t *qp_offset,
			 dma_addr_t phys, int local_size,
			 struct scif_dev *scifdev)
{
	void *local_q;
	void *remote_q;
	struct scif_qp *remote_qp;
	int remote_size;
	int err = 0;

	spin_lock_init(&qp->send_lock);
	spin_lock_init(&qp->recv_lock);
	/* Start by figuring out where we need to point */
	remote_qp = scif_ioremap(phys, sizeof(struct scif_qp), scifdev);
	if (!remote_qp)
		return -EIO;
	qp->remote_qp = remote_qp;
	if (qp->remote_qp->magic != SCIFEP_MAGIC) {
		err = -EIO;
		goto iounmap;
	}
	qp->remote_buf = remote_qp->local_buf;
	remote_size = qp->remote_qp->inbound_q.size;
	remote_q = scif_ioremap(qp->remote_buf, remote_size, scifdev);
	if (!remote_q) {
		err = -EIO;
		goto iounmap;
	}
	qp->remote_qp->local_write = 0;
	/*
	 * To setup the outbound_q, the buffer lives in remote memory,
	 * the read pointer is local, the write pointer is remote
	 */
	scif_rb_init(&qp->outbound_q,
		     &qp->local_read,
		     &qp->remote_qp->local_write,
		     remote_q,
		     get_count_order(remote_size));
	local_q = kzalloc(local_size, GFP_KERNEL);
	if (!local_q) {
		err = -ENOMEM;
		goto iounmap_1;
	}
	err = scif_map_single(&qp->local_buf, local_q, scifdev, local_size);
	if (err)
		goto kfree;
	qp->remote_qp->local_read = 0;
	/*
	 * To setup the inbound_q, the buffer lives locally, the read pointer
	 * is remote and the write pointer is local
	 */
	scif_rb_init(&qp->inbound_q,
		     &qp->remote_qp->local_read,
		     &qp->local_write,
		     local_q, get_count_order(local_size));
	err = scif_map_single(qp_offset, qp, scifdev,
			      sizeof(struct scif_qp));
	if (err)
		goto unmap;
	qp->local_qp = *qp_offset;
	return err;
unmap:
	scif_unmap_single(qp->local_buf, scifdev, local_size);
	qp->local_buf = 0;
kfree:
	kfree(local_q);
iounmap_1:
	scif_iounmap(remote_q, remote_size, scifdev);
	qp->outbound_q.rb_base = NULL;
iounmap:
	scif_iounmap(qp->remote_qp, sizeof(struct scif_qp), scifdev);
	qp->remote_qp = NULL;
	return err;
}

int scif_setup_qp_connect_response(struct scif_dev *scifdev,
				   struct scif_qp *qp, u64 payload)
{
	int err = 0;
	void *r_buf;
	int remote_size;
	phys_addr_t tmp_phys;

	qp->remote_qp = scif_ioremap(payload, sizeof(struct scif_qp), scifdev);

	if (!qp->remote_qp) {
		err = -ENOMEM;
		goto error;
	}

	if (qp->remote_qp->magic != SCIFEP_MAGIC) {
		dev_err(&scifdev->sdev->dev,
			"SCIFEP_MAGIC mismatch between self %d remote %d\n",
			scif_dev[scif_info.nodeid].node, scifdev->node);
		err = -ENODEV;
		goto error;
	}

	tmp_phys = qp->remote_qp->local_buf;
	remote_size = qp->remote_qp->inbound_q.size;
	r_buf = scif_ioremap(tmp_phys, remote_size, scifdev);

	if (!r_buf)
		return -EIO;

	qp->local_read = 0;
	scif_rb_init(&qp->outbound_q,
		     &qp->local_read,
		     &qp->remote_qp->local_write,
		     r_buf,
		     get_count_order(remote_size));
	/*
	 * resetup the inbound_q now that we know where the
	 * inbound_read really is.
	 */
	scif_rb_init(&qp->inbound_q,
		     &qp->remote_qp->local_read,
		     &qp->local_write,
		     qp->inbound_q.rb_base,
		     get_count_order(qp->inbound_q.size));
error:
	return err;
}

static __always_inline void
scif_send_msg_intr(struct scif_dev *scifdev)
{
	struct scif_hw_dev *sdev = scifdev->sdev;

	if (scifdev_is_p2p(scifdev))
		sdev->hw_ops->send_p2p_intr(sdev, scifdev->rdb, &scifdev->mmio);
	else
		sdev->hw_ops->send_intr(sdev, scifdev->rdb);
}

int scif_qp_response(phys_addr_t phys, struct scif_dev *scifdev)
{
	int err = 0;
	struct scifmsg msg;

	err = scif_setup_qp_connect_response(scifdev, scifdev->qpairs, phys);
	if (!err) {
		/*
		 * Now that everything is setup and mapped, we're ready
		 * to tell the peer about our queue's location
		 */
		msg.uop = SCIF_INIT;
		msg.dst.node = scifdev->node;
		err = scif_nodeqp_send(scifdev, &msg);
	}
	return err;
}

void scif_send_exit(struct scif_dev *scifdev)
{
	struct scifmsg msg;
	int ret;

	scifdev->exit = OP_IN_PROGRESS;
	msg.uop = SCIF_EXIT;
	msg.src.node = scif_info.nodeid;
	msg.dst.node = scifdev->node;
	ret = scif_nodeqp_send(scifdev, &msg);
	if (ret)
		goto done;
	/* Wait for a SCIF_EXIT_ACK message */
	wait_event_timeout(scif_info.exitwq, scifdev->exit == OP_COMPLETED,
			   SCIF_NODE_ALIVE_TIMEOUT);
done:
	scifdev->exit = OP_IDLE;
}

int scif_setup_qp(struct scif_dev *scifdev)
{
	int err = 0;
	int local_size;
	struct scif_qp *qp;

	local_size = SCIF_NODE_QP_SIZE;

	qp = kzalloc(sizeof(*qp), GFP_KERNEL);
	if (!qp) {
		err = -ENOMEM;
		return err;
	}
	qp->magic = SCIFEP_MAGIC;
	scifdev->qpairs = qp;
	err = scif_setup_qp_connect(qp, &scifdev->qp_dma_addr,
				    local_size, scifdev);
	if (err)
		goto free_qp;
	/*
	 * We're as setup as we can be. The inbound_q is setup, w/o a usable
	 * outbound q.  When we get a message, the read_ptr will be updated,
	 * and we will pull the message.
	 */
	return err;
free_qp:
	kfree(scifdev->qpairs);
	scifdev->qpairs = NULL;
	return err;
}

static void scif_p2p_freesg(struct scatterlist *sg)
{
	kfree(sg);
}

static struct scatterlist *
scif_p2p_setsg(phys_addr_t pa, int page_size, int page_cnt)
{
	struct scatterlist *sg;
	struct page *page;
	int i;

	sg = kcalloc(page_cnt, sizeof(struct scatterlist), GFP_KERNEL);
	if (!sg)
		return NULL;
	sg_init_table(sg, page_cnt);
	for (i = 0; i < page_cnt; i++) {
		page = pfn_to_page(pa >> PAGE_SHIFT);
		sg_set_page(&sg[i], page, page_size, 0);
		pa += page_size;
	}
	return sg;
}

/* Init p2p mappings required to access peerdev from scifdev */
static struct scif_p2p_info *
scif_init_p2p_info(struct scif_dev *scifdev, struct scif_dev *peerdev)
{
	struct scif_p2p_info *p2p;
	int num_mmio_pages, num_aper_pages, sg_page_shift, err, num_aper_chunks;
	struct scif_hw_dev *psdev = peerdev->sdev;
	struct scif_hw_dev *sdev = scifdev->sdev;

	num_mmio_pages = psdev->mmio->len >> PAGE_SHIFT;
	num_aper_pages = psdev->aper->len >> PAGE_SHIFT;

	p2p = kzalloc(sizeof(*p2p), GFP_KERNEL);
	if (!p2p)
		return NULL;
	p2p->ppi_sg[SCIF_PPI_MMIO] = scif_p2p_setsg(psdev->mmio->pa,
						    PAGE_SIZE, num_mmio_pages);
	if (!p2p->ppi_sg[SCIF_PPI_MMIO])
		goto free_p2p;
	p2p->sg_nentries[SCIF_PPI_MMIO] = num_mmio_pages;
	sg_page_shift = get_order(min(psdev->aper->len, (u64)(1 << 30)));
	num_aper_chunks = num_aper_pages >> (sg_page_shift - PAGE_SHIFT);
	p2p->ppi_sg[SCIF_PPI_APER] = scif_p2p_setsg(psdev->aper->pa,
						    1 << sg_page_shift,
						    num_aper_chunks);
	p2p->sg_nentries[SCIF_PPI_APER] = num_aper_chunks;
	err = dma_map_sg(&sdev->dev, p2p->ppi_sg[SCIF_PPI_MMIO],
			 num_mmio_pages, PCI_DMA_BIDIRECTIONAL);
	if (err != num_mmio_pages)
		goto scif_p2p_free;
	err = dma_map_sg(&sdev->dev, p2p->ppi_sg[SCIF_PPI_APER],
			 num_aper_chunks, PCI_DMA_BIDIRECTIONAL);
	if (err != num_aper_chunks)
		goto dma_unmap;
	p2p->ppi_da[SCIF_PPI_MMIO] = sg_dma_address(p2p->ppi_sg[SCIF_PPI_MMIO]);
	p2p->ppi_da[SCIF_PPI_APER] = sg_dma_address(p2p->ppi_sg[SCIF_PPI_APER]);
	p2p->ppi_len[SCIF_PPI_MMIO] = num_mmio_pages;
	p2p->ppi_len[SCIF_PPI_APER] = num_aper_pages;
	p2p->ppi_peer_id = peerdev->node;
	return p2p;
dma_unmap:
	dma_unmap_sg(&sdev->dev, p2p->ppi_sg[SCIF_PPI_MMIO],
		     p2p->sg_nentries[SCIF_PPI_MMIO], DMA_BIDIRECTIONAL);
scif_p2p_free:
	scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_MMIO]);
	scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_APER]);
free_p2p:
	kfree(p2p);
	return NULL;
}

/**
 * scif_node_connect: Respond to SCIF_NODE_CONNECT interrupt message
 * @dst: Destination node
 *
 * Connect the src and dst node by setting up the p2p connection
 * between them. Management node here acts like a proxy.
 */
static void scif_node_connect(struct scif_dev *scifdev, int dst)
{
	struct scif_dev *dev_j = scifdev;
	struct scif_dev *dev_i = NULL;
	struct scif_p2p_info *p2p_ij = NULL;    /* bus addr for j from i */
	struct scif_p2p_info *p2p_ji = NULL;    /* bus addr for i from j */
	struct scif_p2p_info *p2p;
	struct list_head *pos, *tmp;
	struct scifmsg msg;
	int err;
	u64 tmppayload;

	if (dst < 1 || dst > scif_info.maxid)
		return;

	dev_i = &scif_dev[dst];

	if (!_scifdev_alive(dev_i))
		return;
	/*
	 * If the p2p connection is already setup or in the process of setting
	 * up then just ignore this request. The requested node will get
	 * informed by SCIF_NODE_ADD_ACK or SCIF_NODE_ADD_NACK
	 */
	if (!list_empty(&dev_i->p2p)) {
		list_for_each_safe(pos, tmp, &dev_i->p2p) {
			p2p = list_entry(pos, struct scif_p2p_info, ppi_list);
			if (p2p->ppi_peer_id == dev_j->node)
				return;
		}
	}
	p2p_ij = scif_init_p2p_info(dev_i, dev_j);
	if (!p2p_ij)
		return;
	p2p_ji = scif_init_p2p_info(dev_j, dev_i);
	if (!p2p_ji)
		return;
	list_add_tail(&p2p_ij->ppi_list, &dev_i->p2p);
	list_add_tail(&p2p_ji->ppi_list, &dev_j->p2p);

	/*
	 * Send a SCIF_NODE_ADD to dev_i, pass it its bus address
	 * as seen from dev_j
	 */
	msg.uop = SCIF_NODE_ADD;
	msg.src.node = dev_j->node;
	msg.dst.node = dev_i->node;

	msg.payload[0] = p2p_ji->ppi_da[SCIF_PPI_APER];
	msg.payload[1] = p2p_ij->ppi_da[SCIF_PPI_MMIO];
	msg.payload[2] = p2p_ij->ppi_da[SCIF_PPI_APER];
	msg.payload[3] = p2p_ij->ppi_len[SCIF_PPI_APER] << PAGE_SHIFT;

	err = scif_nodeqp_send(dev_i,  &msg);
	if (err) {
		dev_err(&scifdev->sdev->dev,
			"%s %d error %d\n", __func__, __LINE__, err);
		return;
	}

	/* Same as above but to dev_j */
	msg.uop = SCIF_NODE_ADD;
	msg.src.node = dev_i->node;
	msg.dst.node = dev_j->node;

	tmppayload = msg.payload[0];
	msg.payload[0] = msg.payload[2];
	msg.payload[2] = tmppayload;
	msg.payload[1] = p2p_ji->ppi_da[SCIF_PPI_MMIO];
	msg.payload[3] = p2p_ji->ppi_len[SCIF_PPI_APER] << PAGE_SHIFT;

	scif_nodeqp_send(dev_j, &msg);
}

static void scif_p2p_setup(void)
{
	int i, j;

	if (!scif_info.p2p_enable)
		return;

	for (i = 1; i <= scif_info.maxid; i++)
		if (!_scifdev_alive(&scif_dev[i]))
			return;

	for (i = 1; i <= scif_info.maxid; i++) {
		for (j = 1; j <= scif_info.maxid; j++) {
			struct scif_dev *scifdev = &scif_dev[i];

			if (i == j)
				continue;
			scif_node_connect(scifdev, j);
		}
	}
}

void scif_qp_response_ack(struct work_struct *work)
{
	struct scif_dev *scifdev = container_of(work, struct scif_dev,
						init_msg_work);
	struct scif_peer_dev *spdev;

	/* Drop the INIT message if it has already been received */
	if (_scifdev_alive(scifdev))
		return;

	spdev = scif_peer_register_device(scifdev);
	if (IS_ERR(spdev))
		return;

	if (scif_is_mgmt_node()) {
		mutex_lock(&scif_info.conflock);
		scif_p2p_setup();
		mutex_unlock(&scif_info.conflock);
	}
}

static char *message_types[] = {"BAD",
				"INIT",
				"EXIT",
				"SCIF_EXIT_ACK",
				"SCIF_NODE_ADD",
				"SCIF_NODE_ADD_ACK",
				"SCIF_NODE_ADD_NACK",
				"REMOVE_NODE",
				"REMOVE_NODE_ACK",
				"CNCT_REQ",
				"CNCT_GNT",
				"CNCT_GNTACK",
				"CNCT_GNTNACK",
				"CNCT_REJ",
				"DISCNCT",
				"DISCNT_ACK",
				"CLIENT_SENT",
				"CLIENT_RCVD",
				"SCIF_GET_NODE_INFO"};

static void
scif_display_message(struct scif_dev *scifdev, struct scifmsg *msg,
		     const char *label)
{
	if (!scif_info.en_msg_log)
		return;
	if (msg->uop > SCIF_MAX_MSG) {
		dev_err(&scifdev->sdev->dev,
			"%s: unknown msg type %d\n", label, msg->uop);
		return;
	}
	dev_info(&scifdev->sdev->dev,
		 "%s: msg type %s, src %d:%d, dest %d:%d payload 0x%llx:0x%llx:0x%llx:0x%llx\n",
		 label, message_types[msg->uop], msg->src.node, msg->src.port,
		 msg->dst.node, msg->dst.port, msg->payload[0], msg->payload[1],
		 msg->payload[2], msg->payload[3]);
}

int _scif_nodeqp_send(struct scif_dev *scifdev, struct scifmsg *msg)
{
	struct scif_qp *qp = scifdev->qpairs;
	int err = -ENOMEM, loop_cnt = 0;

	scif_display_message(scifdev, msg, "Sent");
	if (!qp) {
		err = -EINVAL;
		goto error;
	}
	spin_lock(&qp->send_lock);

	while ((err = scif_rb_write(&qp->outbound_q,
				    msg, sizeof(struct scifmsg)))) {
		mdelay(1);
#define SCIF_NODEQP_SEND_TO_MSEC (3 * 1000)
		if (loop_cnt++ > (SCIF_NODEQP_SEND_TO_MSEC)) {
			err = -ENODEV;
			break;
		}
	}
	if (!err)
		scif_rb_commit(&qp->outbound_q);
	spin_unlock(&qp->send_lock);
	if (!err) {
		if (scifdev_self(scifdev))
			/*
			 * For loopback we need to emulate an interrupt by
			 * queuing work for the queue handling real node
			 * Qp interrupts.
			 */
			queue_work(scifdev->intr_wq, &scifdev->intr_bh);
		else
			scif_send_msg_intr(scifdev);
	}
error:
	if (err)
		dev_dbg(&scifdev->sdev->dev,
			"%s %d error %d uop %d\n",
			 __func__, __LINE__, err, msg->uop);
	return err;
}

/**
 * scif_nodeqp_send - Send a message on the node queue pair
 * @scifdev: Scif Device.
 * @msg: The message to be sent.
 */
int scif_nodeqp_send(struct scif_dev *scifdev, struct scifmsg *msg)
{
	int err;
	struct device *spdev = NULL;

	if (msg->uop > SCIF_EXIT_ACK) {
		/* Dont send messages once the exit flow has begun */
		if (OP_IDLE != scifdev->exit)
			return -ENODEV;
		spdev = scif_get_peer_dev(scifdev);
		if (IS_ERR(spdev)) {
			err = PTR_ERR(spdev);
			return err;
		}
	}
	err = _scif_nodeqp_send(scifdev, msg);
	if (msg->uop > SCIF_EXIT_ACK)
		scif_put_peer_dev(spdev);
	return err;
}

/*
 * scif_misc_handler:
 *
 * Work queue handler for servicing miscellaneous SCIF tasks.
 * Examples include:
 * 1) Cleanup of zombie endpoints.
 */
void scif_misc_handler(struct work_struct *work)
{
	scif_cleanup_zombie_epd();
}

/**
 * scif_init() - Respond to SCIF_INIT interrupt message
 * @scifdev:    Remote SCIF device node
 * @msg:        Interrupt message
 */
static __always_inline void
scif_init(struct scif_dev *scifdev, struct scifmsg *msg)
{
	/*
	 * Allow the thread waiting for device page updates for the peer QP DMA
	 * address to complete initializing the inbound_q.
	 */
	flush_delayed_work(&scifdev->qp_dwork);
	/*
	 * Delegate the peer device registration to a workqueue, otherwise if
	 * SCIF client probe (called during peer device registration) calls
	 * scif_connect(..), it will block the message processing thread causing
	 * a deadlock.
	 */
	schedule_work(&scifdev->init_msg_work);
}

/**
 * scif_exit() - Respond to SCIF_EXIT interrupt message
 * @scifdev:    Remote SCIF device node
 * @msg:        Interrupt message
 *
 * This function stops the SCIF interface for the node which sent
 * the SCIF_EXIT message and starts waiting for that node to
 * resetup the queue pair again.
 */
static __always_inline void
scif_exit(struct scif_dev *scifdev, struct scifmsg *unused)
{
	scifdev->exit_ack_pending = true;
	if (scif_is_mgmt_node())
		scif_disconnect_node(scifdev->node, false);
	else
		scif_stop(scifdev);
	schedule_delayed_work(&scifdev->qp_dwork,
			      msecs_to_jiffies(1000));
}

/**
 * scif_exitack() - Respond to SCIF_EXIT_ACK interrupt message
 * @scifdev:    Remote SCIF device node
 * @msg:        Interrupt message
 *
 */
static __always_inline void
scif_exit_ack(struct scif_dev *scifdev, struct scifmsg *unused)
{
	scifdev->exit = OP_COMPLETED;
	wake_up(&scif_info.exitwq);
}

/**
 * scif_node_add() - Respond to SCIF_NODE_ADD interrupt message
 * @scifdev:    Remote SCIF device node
 * @msg:        Interrupt message
 *
 * When the mgmt node driver has finished initializing a MIC node queue pair it
 * marks the node as online. It then looks for all currently online MIC cards
 * and send a SCIF_NODE_ADD message to identify the ID of the new card for
 * peer to peer initialization
 *
 * The local node allocates its incoming queue and sends its address in the
 * SCIF_NODE_ADD_ACK message back to the mgmt node, the mgmt node "reflects"
 * this message to the new node
 */
static __always_inline void
scif_node_add(struct scif_dev *scifdev, struct scifmsg *msg)
{
	struct scif_dev *newdev;
	dma_addr_t qp_offset;
	int qp_connect;
	struct scif_hw_dev *sdev;

	dev_dbg(&scifdev->sdev->dev,
		"Scifdev %d:%d received NODE_ADD msg for node %d\n",
		scifdev->node, msg->dst.node, msg->src.node);
	dev_dbg(&scifdev->sdev->dev,
		"Remote address for this node's aperture %llx\n",
		msg->payload[0]);
	newdev = &scif_dev[msg->src.node];
	newdev->node = msg->src.node;
	newdev->sdev = scif_dev[SCIF_MGMT_NODE].sdev;
	sdev = newdev->sdev;

	if (scif_setup_intr_wq(newdev)) {
		dev_err(&scifdev->sdev->dev,
			"failed to setup interrupts for %d\n", msg->src.node);
		goto interrupt_setup_error;
	}
	newdev->mmio.va = ioremap_nocache(msg->payload[1], sdev->mmio->len);
	if (!newdev->mmio.va) {
		dev_err(&scifdev->sdev->dev,
			"failed to map mmio for %d\n", msg->src.node);
		goto mmio_map_error;
	}
	newdev->qpairs = kzalloc(sizeof(*newdev->qpairs), GFP_KERNEL);
	if (!newdev->qpairs)
		goto qp_alloc_error;
	/*
	 * Set the base address of the remote node's memory since it gets
	 * added to qp_offset
	 */
	newdev->base_addr = msg->payload[0];

	qp_connect = scif_setup_qp_connect(newdev->qpairs, &qp_offset,
					   SCIF_NODE_QP_SIZE, newdev);
	if (qp_connect) {
		dev_err(&scifdev->sdev->dev,
			"failed to setup qp_connect %d\n", qp_connect);
		goto qp_connect_error;
	}

	newdev->db = sdev->hw_ops->next_db(sdev);
	newdev->cookie = sdev->hw_ops->request_irq(sdev, scif_intr_handler,
						   "SCIF_INTR", newdev,
						   newdev->db);
	if (IS_ERR(newdev->cookie))
		goto qp_connect_error;
	newdev->qpairs->magic = SCIFEP_MAGIC;
	newdev->qpairs->qp_state = SCIF_QP_OFFLINE;

	msg->uop = SCIF_NODE_ADD_ACK;
	msg->dst.node = msg->src.node;
	msg->src.node = scif_info.nodeid;
	msg->payload[0] = qp_offset;
	msg->payload[2] = newdev->db;
	scif_nodeqp_send(&scif_dev[SCIF_MGMT_NODE], msg);
	return;
qp_connect_error:
	kfree(newdev->qpairs);
	newdev->qpairs = NULL;
qp_alloc_error:
	iounmap(newdev->mmio.va);
	newdev->mmio.va = NULL;
mmio_map_error:
interrupt_setup_error:
	dev_err(&scifdev->sdev->dev,
		"node add failed for node %d\n", msg->src.node);
	msg->uop = SCIF_NODE_ADD_NACK;
	msg->dst.node = msg->src.node;
	msg->src.node = scif_info.nodeid;
	scif_nodeqp_send(&scif_dev[SCIF_MGMT_NODE], msg);
}

void scif_poll_qp_state(struct work_struct *work)
{
#define SCIF_NODE_QP_RETRY 100
#define SCIF_NODE_QP_TIMEOUT 100
	struct scif_dev *peerdev = container_of(work, struct scif_dev,
							p2p_dwork.work);
	struct scif_qp *qp = &peerdev->qpairs[0];

	if (qp->qp_state != SCIF_QP_ONLINE ||
	    qp->remote_qp->qp_state != SCIF_QP_ONLINE) {
		if (peerdev->p2p_retry++ == SCIF_NODE_QP_RETRY) {
			dev_err(&peerdev->sdev->dev,
				"Warning: QP check timeout with state %d\n",
				qp->qp_state);
			goto timeout;
		}
		schedule_delayed_work(&peerdev->p2p_dwork,
				      msecs_to_jiffies(SCIF_NODE_QP_TIMEOUT));
		return;
	}
	scif_peer_register_device(peerdev);
	return;
timeout:
	dev_err(&peerdev->sdev->dev,
		"%s %d remote node %d offline,  state = 0x%x\n",
		__func__, __LINE__, peerdev->node, qp->qp_state);
	qp->remote_qp->qp_state = SCIF_QP_OFFLINE;
	scif_cleanup_scifdev(peerdev);
}

/**
 * scif_node_add_ack() - Respond to SCIF_NODE_ADD_ACK interrupt message
 * @scifdev:    Remote SCIF device node
 * @msg:        Interrupt message
 *
 * After a MIC node receives the SCIF_NODE_ADD_ACK message it send this
 * message to the mgmt node to confirm the sequence is finished.
 *
 */
static __always_inline void
scif_node_add_ack(struct scif_dev *scifdev, struct scifmsg *msg)
{
	struct scif_dev *peerdev;
	struct scif_qp *qp;
	struct scif_dev *dst_dev = &scif_dev[msg->dst.node];

	dev_dbg(&scifdev->sdev->dev,
		"Scifdev %d received SCIF_NODE_ADD_ACK msg src %d dst %d\n",
		scifdev->node, msg->src.node, msg->dst.node);
	dev_dbg(&scifdev->sdev->dev,
		"payload %llx %llx %llx %llx\n", msg->payload[0],
		msg->payload[1], msg->payload[2], msg->payload[3]);
	if (scif_is_mgmt_node()) {
		/*
		 * the lock serializes with scif_qp_response_ack. The mgmt node
		 * is forwarding the NODE_ADD_ACK message from src to dst we
		 * need to make sure that the dst has already received a
		 * NODE_ADD for src and setup its end of the qp to dst
		 */
		mutex_lock(&scif_info.conflock);
		msg->payload[1] = scif_info.maxid;
		scif_nodeqp_send(dst_dev, msg);
		mutex_unlock(&scif_info.conflock);
		return;
	}
	peerdev = &scif_dev[msg->src.node];
	peerdev->sdev = scif_dev[SCIF_MGMT_NODE].sdev;
	peerdev->node = msg->src.node;

	qp = &peerdev->qpairs[0];

	if ((scif_setup_qp_connect_response(peerdev, &peerdev->qpairs[0],
					    msg->payload[0])))
		goto local_error;
	peerdev->rdb = msg->payload[2];
	qp->remote_qp->qp_state = SCIF_QP_ONLINE;
	schedule_delayed_work(&peerdev->p2p_dwork, 0);
	return;
local_error:
	scif_cleanup_scifdev(peerdev);
}

/**
 * scif_node_add_nack: Respond to SCIF_NODE_ADD_NACK interrupt message
 * @msg:        Interrupt message
 *
 * SCIF_NODE_ADD failed, so inform the waiting wq.
 */
static __always_inline void
scif_node_add_nack(struct scif_dev *scifdev, struct scifmsg *msg)
{
	if (scif_is_mgmt_node()) {
		struct scif_dev *dst_dev = &scif_dev[msg->dst.node];

		dev_dbg(&scifdev->sdev->dev,
			"SCIF_NODE_ADD_NACK received from %d\n", scifdev->node);
		scif_nodeqp_send(dst_dev, msg);
	}
}

/*
 * scif_node_remove: Handle SCIF_NODE_REMOVE message
 * @msg: Interrupt message
 *
 * Handle node removal.
 */
static __always_inline void
scif_node_remove(struct scif_dev *scifdev, struct scifmsg *msg)
{
	int node = msg->payload[0];
	struct scif_dev *scdev = &scif_dev[node];

	scdev->node_remove_ack_pending = true;
	scif_handle_remove_node(node);
}

/*
 * scif_node_remove_ack: Handle SCIF_NODE_REMOVE_ACK message
 * @msg: Interrupt message
 *
 * The peer has acked a SCIF_NODE_REMOVE message.
 */
static __always_inline void
scif_node_remove_ack(struct scif_dev *scifdev, struct scifmsg *msg)
{
	struct scif_dev *sdev = &scif_dev[msg->payload[0]];

	atomic_inc(&sdev->disconn_rescnt);
	wake_up(&sdev->disconn_wq);
}

/**
 * scif_get_node_info: Respond to SCIF_GET_NODE_INFO interrupt message
 * @msg:        Interrupt message
 *
 * Retrieve node info i.e maxid and total from the mgmt node.
 */
static __always_inline void
scif_get_node_info_resp(struct scif_dev *scifdev, struct scifmsg *msg)
{
	if (scif_is_mgmt_node()) {
		swap(msg->dst.node, msg->src.node);
		mutex_lock(&scif_info.conflock);
		msg->payload[1] = scif_info.maxid;
		msg->payload[2] = scif_info.total;
		mutex_unlock(&scif_info.conflock);
		scif_nodeqp_send(scifdev, msg);
	} else {
		struct completion *node_info =
			(struct completion *)msg->payload[3];

		mutex_lock(&scif_info.conflock);
		scif_info.maxid = msg->payload[1];
		scif_info.total = msg->payload[2];
		complete_all(node_info);
		mutex_unlock(&scif_info.conflock);
	}
}

static void
scif_msg_unknown(struct scif_dev *scifdev, struct scifmsg *msg)
{
	/* Bogus Node Qp Message? */
	dev_err(&scifdev->sdev->dev,
		"Unknown message 0x%xn scifdev->node 0x%x\n",
		msg->uop, scifdev->node);
}

static void (*scif_intr_func[SCIF_MAX_MSG + 1])
	    (struct scif_dev *, struct scifmsg *msg) = {
	scif_msg_unknown,	/* Error */
	scif_init,		/* SCIF_INIT */
	scif_exit,		/* SCIF_EXIT */
	scif_exit_ack,		/* SCIF_EXIT_ACK */
	scif_node_add,		/* SCIF_NODE_ADD */
	scif_node_add_ack,	/* SCIF_NODE_ADD_ACK */
	scif_node_add_nack,	/* SCIF_NODE_ADD_NACK */
	scif_node_remove,	/* SCIF_NODE_REMOVE */
	scif_node_remove_ack,	/* SCIF_NODE_REMOVE_ACK */
	scif_cnctreq,		/* SCIF_CNCT_REQ */
	scif_cnctgnt,		/* SCIF_CNCT_GNT */
	scif_cnctgnt_ack,	/* SCIF_CNCT_GNTACK */
	scif_cnctgnt_nack,	/* SCIF_CNCT_GNTNACK */
	scif_cnctrej,		/* SCIF_CNCT_REJ */
	scif_discnct,		/* SCIF_DISCNCT */
	scif_discnt_ack,	/* SCIF_DISCNT_ACK */
	scif_clientsend,	/* SCIF_CLIENT_SENT */
	scif_clientrcvd,	/* SCIF_CLIENT_RCVD */
	scif_get_node_info_resp,/* SCIF_GET_NODE_INFO */
};

/**
 * scif_nodeqp_msg_handler() - Common handler for node messages
 * @scifdev: Remote device to respond to
 * @qp: Remote memory pointer
 * @msg: The message to be handled.
 *
 * This routine calls the appropriate routine to handle a Node Qp
 * message receipt
 */
static int scif_max_msg_id = SCIF_MAX_MSG;

static void
scif_nodeqp_msg_handler(struct scif_dev *scifdev,
			struct scif_qp *qp, struct scifmsg *msg)
{
	scif_display_message(scifdev, msg, "Rcvd");

	if (msg->uop > (u32)scif_max_msg_id) {
		/* Bogus Node Qp Message? */
		dev_err(&scifdev->sdev->dev,
			"Unknown message 0x%xn scifdev->node 0x%x\n",
			msg->uop, scifdev->node);
		return;
	}

	scif_intr_func[msg->uop](scifdev, msg);
}

/**
 * scif_nodeqp_intrhandler() - Interrupt handler for node messages
 * @scifdev:    Remote device to respond to
 * @qp:         Remote memory pointer
 *
 * This routine is triggered by the interrupt mechanism.  It reads
 * messages from the node queue RB and calls the Node QP Message handling
 * routine.
 */
void scif_nodeqp_intrhandler(struct scif_dev *scifdev, struct scif_qp *qp)
{
	struct scifmsg msg;
	int read_size;

	do {
		read_size = scif_rb_get_next(&qp->inbound_q, &msg, sizeof(msg));
		if (!read_size)
			break;
		scif_nodeqp_msg_handler(scifdev, qp, &msg);
		/*
		 * The node queue pair is unmapped so skip the read pointer
		 * update after receipt of a SCIF_EXIT_ACK
		 */
		if (SCIF_EXIT_ACK == msg.uop)
			break;
		scif_rb_update_read_ptr(&qp->inbound_q);
	} while (1);
}

/**
 * scif_loopb_wq_handler - Loopback Workqueue Handler.
 * @work: loop back work
 *
 * This work queue routine is invoked by the loopback work queue handler.
 * It grabs the recv lock, dequeues any available messages from the head
 * of the loopback message list, calls the node QP message handler,
 * waits for it to return, then frees up this message and dequeues more
 * elements of the list if available.
 */
static void scif_loopb_wq_handler(struct work_struct *unused)
{
	struct scif_dev *scifdev = scif_info.loopb_dev;
	struct scif_qp *qp = scifdev->qpairs;
	struct scif_loopb_msg *msg;

	do {
		msg = NULL;
		spin_lock(&qp->recv_lock);
		if (!list_empty(&scif_info.loopb_recv_q)) {
			msg = list_first_entry(&scif_info.loopb_recv_q,
					       struct scif_loopb_msg,
					       list);
			list_del(&msg->list);
		}
		spin_unlock(&qp->recv_lock);

		if (msg) {
			scif_nodeqp_msg_handler(scifdev, qp, &msg->msg);
			kfree(msg);
		}
	} while (msg);
}

/**
 * scif_loopb_msg_handler() - Workqueue handler for loopback messages.
 * @scifdev: SCIF device
 * @qp: Queue pair.
 *
 * This work queue routine is triggered when a loopback message is received.
 *
 * We need special handling for receiving Node Qp messages on a loopback SCIF
 * device via two workqueues for receiving messages.
 *
 * The reason we need the extra workqueue which is not required with *normal*
 * non-loopback SCIF devices is the potential classic deadlock described below:
 *
 * Thread A tries to send a message on a loopback SCIF device and blocks since
 * there is no space in the RB while it has the send_lock held or another
 * lock called lock X for example.
 *
 * Thread B: The Loopback Node QP message receive workqueue receives the message
 * and tries to send a message (eg an ACK) to the loopback SCIF device. It tries
 * to grab the send lock again or lock X and deadlocks with Thread A. The RB
 * cannot be drained any further due to this classic deadlock.
 *
 * In order to avoid deadlocks as mentioned above we have an extra level of
 * indirection achieved by having two workqueues.
 * 1) The first workqueue whose handler is scif_loopb_msg_handler reads
 * messages from the Node QP RB, adds them to a list and queues work for the
 * second workqueue.
 *
 * 2) The second workqueue whose handler is scif_loopb_wq_handler dequeues
 * messages from the list, handles them, frees up the memory and dequeues
 * more elements from the list if possible.
 */
int
scif_loopb_msg_handler(struct scif_dev *scifdev, struct scif_qp *qp)
{
	int read_size;
	struct scif_loopb_msg *msg;

	do {
		msg = kmalloc(sizeof(*msg), GFP_KERNEL);
		if (!msg)
			return -ENOMEM;
		read_size = scif_rb_get_next(&qp->inbound_q, &msg->msg,
					     sizeof(struct scifmsg));
		if (read_size != sizeof(struct scifmsg)) {
			kfree(msg);
			scif_rb_update_read_ptr(&qp->inbound_q);
			break;
		}
		spin_lock(&qp->recv_lock);
		list_add_tail(&msg->list, &scif_info.loopb_recv_q);
		spin_unlock(&qp->recv_lock);
		queue_work(scif_info.loopb_wq, &scif_info.loopb_work);
		scif_rb_update_read_ptr(&qp->inbound_q);
	} while (read_size == sizeof(struct scifmsg));
	return read_size;
}

/**
 * scif_setup_loopback_qp - One time setup work for Loopback Node Qp.
 * @scifdev: SCIF device
 *
 * Sets up the required loopback workqueues, queue pairs and ring buffers
 */
int scif_setup_loopback_qp(struct scif_dev *scifdev)
{
	int err = 0;
	void *local_q;
	struct scif_qp *qp;
	struct scif_peer_dev *spdev;

	err = scif_setup_intr_wq(scifdev);
	if (err)
		goto exit;
	INIT_LIST_HEAD(&scif_info.loopb_recv_q);
	snprintf(scif_info.loopb_wqname, sizeof(scif_info.loopb_wqname),
		 "SCIF LOOPB %d", scifdev->node);
	scif_info.loopb_wq =
		alloc_ordered_workqueue(scif_info.loopb_wqname, 0);
	if (!scif_info.loopb_wq) {
		err = -ENOMEM;
		goto destroy_intr;
	}
	INIT_WORK(&scif_info.loopb_work, scif_loopb_wq_handler);
	/* Allocate Self Qpair */
	scifdev->qpairs = kzalloc(sizeof(*scifdev->qpairs), GFP_KERNEL);
	if (!scifdev->qpairs) {
		err = -ENOMEM;
		goto destroy_loopb_wq;
	}

	qp = scifdev->qpairs;
	qp->magic = SCIFEP_MAGIC;
	spin_lock_init(&qp->send_lock);
	spin_lock_init(&qp->recv_lock);

	local_q = kzalloc(SCIF_NODE_QP_SIZE, GFP_KERNEL);
	if (!local_q) {
		err = -ENOMEM;
		goto free_qpairs;
	}
	/*
	 * For loopback the inbound_q and outbound_q are essentially the same
	 * since the Node sends a message on the loopback interface to the
	 * outbound_q which is then received on the inbound_q.
	 */
	scif_rb_init(&qp->outbound_q,
		     &qp->local_read,
		     &qp->local_write,
		     local_q, get_count_order(SCIF_NODE_QP_SIZE));

	scif_rb_init(&qp->inbound_q,
		     &qp->local_read,
		     &qp->local_write,
		     local_q, get_count_order(SCIF_NODE_QP_SIZE));
	scif_info.nodeid = scifdev->node;
	spdev = scif_peer_register_device(scifdev);
	if (IS_ERR(spdev)) {
		err = PTR_ERR(spdev);
		goto free_local_q;
	}
	scif_info.loopb_dev = scifdev;
	return err;
free_local_q:
	kfree(local_q);
free_qpairs:
	kfree(scifdev->qpairs);
destroy_loopb_wq:
	destroy_workqueue(scif_info.loopb_wq);
destroy_intr:
	scif_destroy_intr_wq(scifdev);
exit:
	return err;
}

/**
 * scif_destroy_loopback_qp - One time uninit work for Loopback Node Qp
 * @scifdev: SCIF device
 *
 * Destroys the workqueues and frees up the Ring Buffer and Queue Pair memory.
 */
int scif_destroy_loopback_qp(struct scif_dev *scifdev)
{
	struct scif_peer_dev *spdev;

	rcu_read_lock();
	spdev = rcu_dereference(scifdev->spdev);
	rcu_read_unlock();
	if (spdev)
		scif_peer_unregister_device(spdev);
	destroy_workqueue(scif_info.loopb_wq);
	scif_destroy_intr_wq(scifdev);
	kfree(scifdev->qpairs->outbound_q.rb_base);
	kfree(scifdev->qpairs);
	scifdev->sdev = NULL;
	scif_info.loopb_dev = NULL;
	return 0;
}

void scif_destroy_p2p(struct scif_dev *scifdev)
{
	struct scif_dev *peer_dev;
	struct scif_p2p_info *p2p;
	struct list_head *pos, *tmp;
	int bd;

	mutex_lock(&scif_info.conflock);
	/* Free P2P mappings in the given node for all its peer nodes */
	list_for_each_safe(pos, tmp, &scifdev->p2p) {
		p2p = list_entry(pos, struct scif_p2p_info, ppi_list);
		dma_unmap_sg(&scifdev->sdev->dev, p2p->ppi_sg[SCIF_PPI_MMIO],
			     p2p->sg_nentries[SCIF_PPI_MMIO],
			     DMA_BIDIRECTIONAL);
		dma_unmap_sg(&scifdev->sdev->dev, p2p->ppi_sg[SCIF_PPI_APER],
			     p2p->sg_nentries[SCIF_PPI_APER],
			     DMA_BIDIRECTIONAL);
		scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_MMIO]);
		scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_APER]);
		list_del(pos);
		kfree(p2p);
	}

	/* Free P2P mapping created in the peer nodes for the given node */
	for (bd = SCIF_MGMT_NODE + 1; bd <= scif_info.maxid; bd++) {
		peer_dev = &scif_dev[bd];
		list_for_each_safe(pos, tmp, &peer_dev->p2p) {
			p2p = list_entry(pos, struct scif_p2p_info, ppi_list);
			if (p2p->ppi_peer_id == scifdev->node) {
				dma_unmap_sg(&peer_dev->sdev->dev,
					     p2p->ppi_sg[SCIF_PPI_MMIO],
					     p2p->sg_nentries[SCIF_PPI_MMIO],
					     DMA_BIDIRECTIONAL);
				dma_unmap_sg(&peer_dev->sdev->dev,
					     p2p->ppi_sg[SCIF_PPI_APER],
					     p2p->sg_nentries[SCIF_PPI_APER],
					     DMA_BIDIRECTIONAL);
				scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_MMIO]);
				scif_p2p_freesg(p2p->ppi_sg[SCIF_PPI_APER]);
				list_del(pos);
				kfree(p2p);
			}
		}
	}
	mutex_unlock(&scif_info.conflock);
}