aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/hvsi.c
blob: a0370ed752ce01725b4458fb00335adb5ccb905f (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
/*
 * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

/* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
 * and the service processor on IBM pSeries servers. On these servers, there
 * are no serial ports under the OS's control, and sometimes there is no other
 * console available either. However, the service processor has two standard
 * serial ports, so this over-complicated protocol allows the OS to control
 * those ports by proxy.
 *
 * Besides data, the procotol supports the reading/writing of the serial
 * port's DTR line, and the reading of the CD line. This is to allow the OS to
 * control a modem attached to the service processor's serial port. Note that
 * the OS cannot change the speed of the port through this protocol.
 */

#undef DEBUG

#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/major.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/sysrq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <asm/hvcall.h>
#include <asm/hvconsole.h>
#include <asm/prom.h>
#include <asm/uaccess.h>
#include <asm/vio.h>
#include <asm/param.h>

#define HVSI_MAJOR	229
#define HVSI_MINOR	128
#define MAX_NR_HVSI_CONSOLES 4

#define HVSI_TIMEOUT (5*HZ)
#define HVSI_VERSION 1
#define HVSI_MAX_PACKET 256
#define HVSI_MAX_READ 16
#define HVSI_MAX_OUTGOING_DATA 12
#define N_OUTBUF 12

/*
 * we pass data via two 8-byte registers, so we would like our char arrays
 * properly aligned for those loads.
 */
#define __ALIGNED__	__attribute__((__aligned__(sizeof(long))))

struct hvsi_struct {
	struct work_struct writer;
	struct work_struct handshaker;
	wait_queue_head_t emptyq; /* woken when outbuf is emptied */
	wait_queue_head_t stateq; /* woken when HVSI state changes */
	spinlock_t lock;
	int index;
	struct tty_struct *tty;
	unsigned int count;
	uint8_t throttle_buf[128];
	uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
	/* inbuf is for packet reassembly. leave a little room for leftovers. */
	uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
	uint8_t *inbuf_end;
	int n_throttle;
	int n_outbuf;
	uint32_t vtermno;
	uint32_t virq;
	atomic_t seqno; /* HVSI packet sequence number */
	uint16_t mctrl;
	uint8_t state;  /* HVSI protocol state */
	uint8_t flags;
#ifdef CONFIG_MAGIC_SYSRQ
	uint8_t sysrq;
#endif /* CONFIG_MAGIC_SYSRQ */
};
static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];

static struct tty_driver *hvsi_driver;
static int hvsi_count;
static int (*hvsi_wait)(struct hvsi_struct *hp, int state);

enum HVSI_PROTOCOL_STATE {
	HVSI_CLOSED,
	HVSI_WAIT_FOR_VER_RESPONSE,
	HVSI_WAIT_FOR_VER_QUERY,
	HVSI_OPEN,
	HVSI_WAIT_FOR_MCTRL_RESPONSE,
	HVSI_FSP_DIED,
};
#define HVSI_CONSOLE 0x1

#define VS_DATA_PACKET_HEADER           0xff
#define VS_CONTROL_PACKET_HEADER        0xfe
#define VS_QUERY_PACKET_HEADER          0xfd
#define VS_QUERY_RESPONSE_PACKET_HEADER 0xfc

/* control verbs */
#define VSV_SET_MODEM_CTL    1 /* to service processor only */
#define VSV_MODEM_CTL_UPDATE 2 /* from service processor only */
#define VSV_CLOSE_PROTOCOL   3

/* query verbs */
#define VSV_SEND_VERSION_NUMBER 1
#define VSV_SEND_MODEM_CTL_STATUS 2

/* yes, these masks are not consecutive. */
#define HVSI_TSDTR 0x01
#define HVSI_TSCD  0x20

struct hvsi_header {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
} __attribute__((packed));

struct hvsi_data {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint8_t  data[HVSI_MAX_OUTGOING_DATA];
} __attribute__((packed));

struct hvsi_control {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
	/* optional depending on verb: */
	uint32_t word;
	uint32_t mask;
} __attribute__((packed));

struct hvsi_query {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
} __attribute__((packed));

struct hvsi_query_response {
	uint8_t  type;
	uint8_t  len;
	uint16_t seqno;
	uint16_t verb;
	uint16_t query_seqno;
	union {
		uint8_t  version;
		uint32_t mctrl_word;
	} u;
} __attribute__((packed));



static inline int is_console(struct hvsi_struct *hp)
{
	return hp->flags & HVSI_CONSOLE;
}

static inline int is_open(struct hvsi_struct *hp)
{
	/* if we're waiting for an mctrl then we're already open */
	return (hp->state == HVSI_OPEN)
			|| (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
}

static inline void print_state(struct hvsi_struct *hp)
{
#ifdef DEBUG
	static const char *state_names[] = {
		"HVSI_CLOSED",
		"HVSI_WAIT_FOR_VER_RESPONSE",
		"HVSI_WAIT_FOR_VER_QUERY",
		"HVSI_OPEN",
		"HVSI_WAIT_FOR_MCTRL_RESPONSE",
		"HVSI_FSP_DIED",
	};
	const char *name = state_names[hp->state];

	if (hp->state > ARRAY_SIZE(state_names))
		name = "UNKNOWN";

	pr_debug("hvsi%i: state = %s\n", hp->index, name);
#endif /* DEBUG */
}

static inline void __set_state(struct hvsi_struct *hp, int state)
{
	hp->state = state;
	print_state(hp);
	wake_up_all(&hp->stateq);
}

static inline void set_state(struct hvsi_struct *hp, int state)
{
	unsigned long flags;

	spin_lock_irqsave(&hp->lock, flags);
	__set_state(hp, state);
	spin_unlock_irqrestore(&hp->lock, flags);
}

static inline int len_packet(const uint8_t *packet)
{
	return (int)((struct hvsi_header *)packet)->len;
}

static inline int is_header(const uint8_t *packet)
{
	struct hvsi_header *header = (struct hvsi_header *)packet;
	return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
}

static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
{
	if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
		return 0; /* don't even have the packet header */

	if (hp->inbuf_end < (packet + len_packet(packet)))
		return 0; /* don't have the rest of the packet */

	return 1;
}

/* shift remaining bytes in packetbuf down */
static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
{
	int remaining = (int)(hp->inbuf_end - read_to);

	pr_debug("%s: %i chars remain\n", __FUNCTION__, remaining);

	if (read_to != hp->inbuf)
		memmove(hp->inbuf, read_to, remaining);

	hp->inbuf_end = hp->inbuf + remaining;
}

#ifdef DEBUG
#define dbg_dump_packet(packet) dump_packet(packet)
#define dbg_dump_hex(data, len) dump_hex(data, len)
#else
#define dbg_dump_packet(packet) do { } while (0)
#define dbg_dump_hex(data, len) do { } while (0)
#endif

static void dump_hex(const uint8_t *data, int len)
{
	int i;

	printk("    ");
	for (i=0; i < len; i++)
		printk("%.2x", data[i]);

	printk("\n    ");
	for (i=0; i < len; i++) {
		if (isprint(data[i]))
			printk("%c", data[i]);
		else
			printk(".");
	}
	printk("\n");
}

static void dump_packet(uint8_t *packet)
{
	struct hvsi_header *header = (struct hvsi_header *)packet;

	printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
			header->seqno);

	dump_hex(packet, header->len);
}

static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
{
	unsigned long got;

	got = hvc_get_chars(hp->vtermno, buf, count);

	return got;
}

static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
	struct tty_struct **to_hangup, struct hvsi_struct **to_handshake)
{
	struct hvsi_control *header = (struct hvsi_control *)packet;

	switch (header->verb) {
		case VSV_MODEM_CTL_UPDATE:
			if ((header->word & HVSI_TSCD) == 0) {
				/* CD went away; no more connection */
				pr_debug("hvsi%i: CD dropped\n", hp->index);
				hp->mctrl &= TIOCM_CD;
				if (!(hp->tty->flags & CLOCAL))
					*to_hangup = hp->tty;
			}
			break;
		case VSV_CLOSE_PROTOCOL:
			pr_debug("hvsi%i: service processor came back\n", hp->index);
			if (hp->state != HVSI_CLOSED) {
				*to_handshake = hp;
			}
			break;
		default:
			printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
				hp->index);
			dump_packet(packet);
			break;
	}
}

static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
{
	struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;

	switch (hp->state) {
		case HVSI_WAIT_FOR_VER_RESPONSE:
			__set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
			break;
		case HVSI_WAIT_FOR_MCTRL_RESPONSE:
			hp->mctrl = 0;
			if (resp->u.mctrl_word & HVSI_TSDTR)
				hp->mctrl |= TIOCM_DTR;
			if (resp->u.mctrl_word & HVSI_TSCD)
				hp->mctrl |= TIOCM_CD;
			__set_state(hp, HVSI_OPEN);
			break;
		default:
			printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
			dump_packet(packet);
			break;
	}
}

/* respond to service processor's version query */
static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
{
	struct hvsi_query_response packet __ALIGNED__;
	int wrote;

	packet.type = VS_QUERY_RESPONSE_PACKET_HEADER;
	packet.len = sizeof(struct hvsi_query_response);
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.verb = VSV_SEND_VERSION_NUMBER;
	packet.u.version = HVSI_VERSION;
	packet.query_seqno = query_seqno+1;

	pr_debug("%s: sending %i bytes\n", __FUNCTION__, packet.len);
	dbg_dump_hex((uint8_t*)&packet, packet.len);

	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
	if (wrote != packet.len) {
		printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
			hp->index);
		return -EIO;
	}

	return 0;
}

static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
{
	struct hvsi_query *query = (struct hvsi_query *)packet;

	switch (hp->state) {
		case HVSI_WAIT_FOR_VER_QUERY:
			hvsi_version_respond(hp, query->seqno);
			__set_state(hp, HVSI_OPEN);
			break;
		default:
			printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
			dump_packet(packet);
			break;
	}
}

static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
{
	int i;

	for (i=0; i < len; i++) {
		char c = buf[i];
#ifdef CONFIG_MAGIC_SYSRQ
		if (c == '\0') {
			hp->sysrq = 1;
			continue;
		} else if (hp->sysrq) {
			handle_sysrq(c, NULL, hp->tty);
			hp->sysrq = 0;
			continue;
		}
#endif /* CONFIG_MAGIC_SYSRQ */
		tty_insert_flip_char(hp->tty, c, 0);
	}
}

/*
 * We could get 252 bytes of data at once here. But the tty layer only
 * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
 * it. Accordingly we won't send more than 128 bytes at a time to the flip
 * buffer, which will give the tty buffer a chance to throttle us. Should the
 * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
 * revisited.
 */
#define TTY_THRESHOLD_THROTTLE 128
static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
		const uint8_t *packet)
{
	const struct hvsi_header *header = (const struct hvsi_header *)packet;
	const uint8_t *data = packet + sizeof(struct hvsi_header);
	int datalen = header->len - sizeof(struct hvsi_header);
	int overflow = datalen - TTY_THRESHOLD_THROTTLE;

	pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);

	if (datalen == 0)
		return NULL;

	if (overflow > 0) {
		pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __FUNCTION__);
		datalen = TTY_THRESHOLD_THROTTLE;
	}

	hvsi_insert_chars(hp, data, datalen);

	if (overflow > 0) {
		/*
		 * we still have more data to deliver, so we need to save off the
		 * overflow and send it later
		 */
		pr_debug("%s: deferring overflow\n", __FUNCTION__);
		memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
		hp->n_throttle = overflow;
	}

	return hp->tty;
}

/*
 * Returns true/false indicating data successfully read from hypervisor.
 * Used both to get packets for tty connections and to advance the state
 * machine during console handshaking (in which case tty = NULL and we ignore
 * incoming data).
 */
static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,
		struct tty_struct **hangup, struct hvsi_struct **handshake)
{
	uint8_t *packet = hp->inbuf;
	int chunklen;

	*flip = NULL;
	*hangup = NULL;
	*handshake = NULL;

	chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
	if (chunklen == 0) {
		pr_debug("%s: 0-length read\n", __FUNCTION__);
		return 0;
	}

	pr_debug("%s: got %i bytes\n", __FUNCTION__, chunklen);
	dbg_dump_hex(hp->inbuf_end, chunklen);

	hp->inbuf_end += chunklen;

	/* handle all completed packets */
	while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
		struct hvsi_header *header = (struct hvsi_header *)packet;

		if (!is_header(packet)) {
			printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
			/* skip bytes until we find a header or run out of data */
			while ((packet < hp->inbuf_end) && (!is_header(packet)))
				packet++;
			continue;
		}

		pr_debug("%s: handling %i-byte packet\n", __FUNCTION__,
				len_packet(packet));
		dbg_dump_packet(packet);

		switch (header->type) {
			case VS_DATA_PACKET_HEADER:
				if (!is_open(hp))
					break;
				if (hp->tty == NULL)
					break; /* no tty buffer to put data in */
				*flip = hvsi_recv_data(hp, packet);
				break;
			case VS_CONTROL_PACKET_HEADER:
				hvsi_recv_control(hp, packet, hangup, handshake);
				break;
			case VS_QUERY_RESPONSE_PACKET_HEADER:
				hvsi_recv_response(hp, packet);
				break;
			case VS_QUERY_PACKET_HEADER:
				hvsi_recv_query(hp, packet);
				break;
			default:
				printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
						hp->index, header->type);
				dump_packet(packet);
				break;
		}

		packet += len_packet(packet);

		if (*hangup || *handshake) {
			pr_debug("%s: hangup or handshake\n", __FUNCTION__);
			/*
			 * we need to send the hangup now before receiving any more data.
			 * If we get "data, hangup, data", we can't deliver the second
			 * data before the hangup.
			 */
			break;
		}
	}

	compact_inbuf(hp, packet);

	return 1;
}

static void hvsi_send_overflow(struct hvsi_struct *hp)
{
	pr_debug("%s: delivering %i bytes overflow\n", __FUNCTION__,
			hp->n_throttle);

	hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
	hp->n_throttle = 0;
}

/*
 * must get all pending data because we only get an irq on empty->non-empty
 * transition
 */
static irqreturn_t hvsi_interrupt(int irq, void *arg, struct pt_regs *regs)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)arg;
	struct tty_struct *flip;
	struct tty_struct *hangup;
	struct hvsi_struct *handshake;
	unsigned long flags;
	int again = 1;

	pr_debug("%s\n", __FUNCTION__);

	while (again) {
		spin_lock_irqsave(&hp->lock, flags);
		again = hvsi_load_chunk(hp, &flip, &hangup, &handshake);
		spin_unlock_irqrestore(&hp->lock, flags);

		/*
		 * we have to call tty_flip_buffer_push() and tty_hangup() outside our
		 * spinlock. But we also have to keep going until we've read all the
		 * available data.
		 */

		if (flip) {
			/* there was data put in the tty flip buffer */
			tty_flip_buffer_push(flip);
			flip = NULL;
		}

		if (hangup) {
			tty_hangup(hangup);
		}

		if (handshake) {
			pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
			schedule_work(&handshake->handshaker);
		}
	}

	spin_lock_irqsave(&hp->lock, flags);
	if (hp->tty && hp->n_throttle
			&& (!test_bit(TTY_THROTTLED, &hp->tty->flags))) {
		/* we weren't hung up and we weren't throttled, so we can deliver the
		 * rest now */
		flip = hp->tty;
		hvsi_send_overflow(hp);
	}
	spin_unlock_irqrestore(&hp->lock, flags);

	if (flip) {
		tty_flip_buffer_push(flip);
	}

	return IRQ_HANDLED;
}

/* for boot console, before the irq handler is running */
static int __init poll_for_state(struct hvsi_struct *hp, int state)
{
	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;

	for (;;) {
		hvsi_interrupt(hp->virq, (void *)hp, NULL); /* get pending data */

		if (hp->state == state)
			return 0;

		mdelay(5);
		if (time_after(jiffies, end_jiffies))
			return -EIO;
	}
}

/* wait for irq handler to change our state */
static int wait_for_state(struct hvsi_struct *hp, int state)
{
	int ret = 0;

	if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
		ret = -EIO;

	return ret;
}

static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
{
	struct hvsi_query packet __ALIGNED__;
	int wrote;

	packet.type = VS_QUERY_PACKET_HEADER;
	packet.len = sizeof(struct hvsi_query);
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.verb = verb;

	pr_debug("%s: sending %i bytes\n", __FUNCTION__, packet.len);
	dbg_dump_hex((uint8_t*)&packet, packet.len);

	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
	if (wrote != packet.len) {
		printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
			wrote);
		return -EIO;
	}

	return 0;
}

static int hvsi_get_mctrl(struct hvsi_struct *hp)
{
	int ret;

	set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
	hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);

	ret = hvsi_wait(hp, HVSI_OPEN);
	if (ret < 0) {
		printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
		set_state(hp, HVSI_OPEN);
		return ret;
	}

	pr_debug("%s: mctrl 0x%x\n", __FUNCTION__, hp->mctrl);

	return 0;
}

/* note that we can only set DTR */
static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
{
	struct hvsi_control packet __ALIGNED__;
	int wrote;

	packet.type = VS_CONTROL_PACKET_HEADER,
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.len = sizeof(struct hvsi_control);
	packet.verb = VSV_SET_MODEM_CTL;
	packet.mask = HVSI_TSDTR;

	if (mctrl & TIOCM_DTR)
		packet.word = HVSI_TSDTR;

	pr_debug("%s: sending %i bytes\n", __FUNCTION__, packet.len);
	dbg_dump_hex((uint8_t*)&packet, packet.len);

	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
	if (wrote != packet.len) {
		printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
		return -EIO;
	}

	return 0;
}

static void hvsi_drain_input(struct hvsi_struct *hp)
{
	uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;

	while (time_before(end_jiffies, jiffies))
		if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
			break;
}

static int hvsi_handshake(struct hvsi_struct *hp)
{
	int ret;

	/*
	 * We could have a CLOSE or other data waiting for us before we even try
	 * to open; try to throw it all away so we don't get confused. (CLOSE
	 * is the first message sent up the pipe when the FSP comes online. We
	 * need to distinguish between "it came up a while ago and we're the first
	 * user" and "it was just reset before it saw our handshake packet".)
	 */
	hvsi_drain_input(hp);

	set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
	ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
	if (ret < 0) {
		printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
		return ret;
	}

	ret = hvsi_wait(hp, HVSI_OPEN);
	if (ret < 0)
		return ret;

	return 0;
}

static void hvsi_handshaker(void *arg)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)arg;

	if (hvsi_handshake(hp) >= 0)
		return;

	printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
	if (is_console(hp)) {
		/*
		 * ttys will re-attempt the handshake via hvsi_open, but
		 * the console will not.
		 */
		printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
	}
}

static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
{
	struct hvsi_data packet __ALIGNED__;
	int ret;

	BUG_ON(count > HVSI_MAX_OUTGOING_DATA);

	packet.type = VS_DATA_PACKET_HEADER;
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.len = count + sizeof(struct hvsi_header);
	memcpy(&packet.data, buf, count);

	ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
	if (ret == packet.len) {
		/* return the number of chars written, not the packet length */
		return count;
	}
	return ret; /* return any errors */
}

static void hvsi_close_protocol(struct hvsi_struct *hp)
{
	struct hvsi_control packet __ALIGNED__;

	packet.type = VS_CONTROL_PACKET_HEADER;
	packet.seqno = atomic_inc_return(&hp->seqno);
	packet.len = 6;
	packet.verb = VSV_CLOSE_PROTOCOL;

	pr_debug("%s: sending %i bytes\n", __FUNCTION__, packet.len);
	dbg_dump_hex((uint8_t*)&packet, packet.len);

	hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
}

static int hvsi_open(struct tty_struct *tty, struct file *filp)
{
	struct hvsi_struct *hp;
	unsigned long flags;
	int line = tty->index;
	int ret;

	pr_debug("%s\n", __FUNCTION__);

	if (line < 0 || line >= hvsi_count)
		return -ENODEV;
	hp = &hvsi_ports[line];

	tty->driver_data = hp;
	tty->low_latency = 1; /* avoid throttle/tty_flip_buffer_push race */

	mb();
	if (hp->state == HVSI_FSP_DIED)
		return -EIO;

	spin_lock_irqsave(&hp->lock, flags);
	hp->tty = tty;
	hp->count++;
	atomic_set(&hp->seqno, 0);
	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
	spin_unlock_irqrestore(&hp->lock, flags);

	if (is_console(hp))
		return 0; /* this has already been handshaked as the console */

	ret = hvsi_handshake(hp);
	if (ret < 0) {
		printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
		return ret;
	}

	ret = hvsi_get_mctrl(hp);
	if (ret < 0) {
		printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
		return ret;
	}

	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
	if (ret < 0) {
		printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
		return ret;
	}

	return 0;
}

/* wait for hvsi_write_worker to empty hp->outbuf */
static void hvsi_flush_output(struct hvsi_struct *hp)
{
	wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);

	/* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
	cancel_delayed_work(&hp->writer);
	flush_scheduled_work();

	/*
	 * it's also possible that our timeout expired and hvsi_write_worker
	 * didn't manage to push outbuf. poof.
	 */
	hp->n_outbuf = 0;
}

static void hvsi_close(struct tty_struct *tty, struct file *filp)
{
	struct hvsi_struct *hp = tty->driver_data;
	unsigned long flags;

	pr_debug("%s\n", __FUNCTION__);

	if (tty_hung_up_p(filp))
		return;

	spin_lock_irqsave(&hp->lock, flags);

	if (--hp->count == 0) {
		hp->tty = NULL;
		hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */

		/* only close down connection if it is not the console */
		if (!is_console(hp)) {
			h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
			__set_state(hp, HVSI_CLOSED);
			/*
			 * any data delivered to the tty layer after this will be
			 * discarded (except for XON/XOFF)
			 */
			tty->closing = 1;

			spin_unlock_irqrestore(&hp->lock, flags);

			/* let any existing irq handlers finish. no more will start. */
			synchronize_irq(hp->virq);

			/* hvsi_write_worker will re-schedule until outbuf is empty. */
			hvsi_flush_output(hp);

			/* tell FSP to stop sending data */
			hvsi_close_protocol(hp);

			/*
			 * drain anything FSP is still in the middle of sending, and let
			 * hvsi_handshake drain the rest on the next open.
			 */
			hvsi_drain_input(hp);

			spin_lock_irqsave(&hp->lock, flags);
		}
	} else if (hp->count < 0)
		printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
		       hp - hvsi_ports, hp->count);

	spin_unlock_irqrestore(&hp->lock, flags);
}

static void hvsi_hangup(struct tty_struct *tty)
{
	struct hvsi_struct *hp = tty->driver_data;
	unsigned long flags;

	pr_debug("%s\n", __FUNCTION__);

	spin_lock_irqsave(&hp->lock, flags);

	hp->count = 0;
	hp->n_outbuf = 0;
	hp->tty = NULL;

	spin_unlock_irqrestore(&hp->lock, flags);
}

/* called with hp->lock held */
static void hvsi_push(struct hvsi_struct *hp)
{
	int n;

	if (hp->n_outbuf <= 0)
		return;

	n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
	if (n > 0) {
		/* success */
		pr_debug("%s: wrote %i chars\n", __FUNCTION__, n);
		hp->n_outbuf = 0;
	} else if (n == -EIO) {
		__set_state(hp, HVSI_FSP_DIED);
		printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
	}
}

/* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
static void hvsi_write_worker(void *arg)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)arg;
	unsigned long flags;
#ifdef DEBUG
	static long start_j = 0;

	if (start_j == 0)
		start_j = jiffies;
#endif /* DEBUG */

	spin_lock_irqsave(&hp->lock, flags);

	pr_debug("%s: %i chars in buffer\n", __FUNCTION__, hp->n_outbuf);

	if (!is_open(hp)) {
		/*
		 * We could have a non-open connection if the service processor died
		 * while we were busily scheduling ourselves. In that case, it could
		 * be minutes before the service processor comes back, so only try
		 * again once a second.
		 */
		schedule_delayed_work(&hp->writer, HZ);
		goto out;
	}

	hvsi_push(hp);
	if (hp->n_outbuf > 0)
		schedule_delayed_work(&hp->writer, 10);
	else {
#ifdef DEBUG
		pr_debug("%s: outbuf emptied after %li jiffies\n", __FUNCTION__,
				jiffies - start_j);
		start_j = 0;
#endif /* DEBUG */
		wake_up_all(&hp->emptyq);
		if (test_bit(TTY_DO_WRITE_WAKEUP, &hp->tty->flags)
				&& hp->tty->ldisc.write_wakeup)
			hp->tty->ldisc.write_wakeup(hp->tty);
		wake_up_interruptible(&hp->tty->write_wait);
	}

out:
	spin_unlock_irqrestore(&hp->lock, flags);
}

static int hvsi_write_room(struct tty_struct *tty)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;

	return N_OUTBUF - hp->n_outbuf;
}

static int hvsi_chars_in_buffer(struct tty_struct *tty)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;

	return hp->n_outbuf;
}

static int hvsi_write(struct tty_struct *tty,
		     const unsigned char *buf, int count)
{
	struct hvsi_struct *hp = tty->driver_data;
	const char *source = buf;
	unsigned long flags;
	int total = 0;
	int origcount = count;

	spin_lock_irqsave(&hp->lock, flags);

	pr_debug("%s: %i chars in buffer\n", __FUNCTION__, hp->n_outbuf);

	if (!is_open(hp)) {
		/* we're either closing or not yet open; don't accept data */
		pr_debug("%s: not open\n", __FUNCTION__);
		goto out;
	}

	/*
	 * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
	 * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
	 * will see there is no room in outbuf and return.
	 */
	while ((count > 0) && (hvsi_write_room(hp->tty) > 0)) {
		int chunksize = min(count, hvsi_write_room(hp->tty));

		BUG_ON(hp->n_outbuf < 0);
		memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
		hp->n_outbuf += chunksize;

		total += chunksize;
		source += chunksize;
		count -= chunksize;
		hvsi_push(hp);
	}

	if (hp->n_outbuf > 0) {
		/*
		 * we weren't able to write it all to the hypervisor.
		 * schedule another push attempt.
		 */
		schedule_delayed_work(&hp->writer, 10);
	}

out:
	spin_unlock_irqrestore(&hp->lock, flags);

	if (total != origcount)
		pr_debug("%s: wanted %i, only wrote %i\n", __FUNCTION__, origcount,
			total);

	return total;
}

/*
 * I have never seen throttle or unthrottle called, so this little throttle
 * buffering scheme may or may not work.
 */
static void hvsi_throttle(struct tty_struct *tty)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;

	pr_debug("%s\n", __FUNCTION__);

	h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
}

static void hvsi_unthrottle(struct tty_struct *tty)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;
	unsigned long flags;
	int shouldflip = 0;

	pr_debug("%s\n", __FUNCTION__);

	spin_lock_irqsave(&hp->lock, flags);
	if (hp->n_throttle) {
		hvsi_send_overflow(hp);
		shouldflip = 1;
	}
	spin_unlock_irqrestore(&hp->lock, flags);

	if (shouldflip)
		tty_flip_buffer_push(hp->tty);

	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
}

static int hvsi_tiocmget(struct tty_struct *tty, struct file *file)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;

	hvsi_get_mctrl(hp);
	return hp->mctrl;
}

static int hvsi_tiocmset(struct tty_struct *tty, struct file *file,
		unsigned int set, unsigned int clear)
{
	struct hvsi_struct *hp = (struct hvsi_struct *)tty->driver_data;
	unsigned long flags;
	uint16_t new_mctrl;

	/* we can only alter DTR */
	clear &= TIOCM_DTR;
	set &= TIOCM_DTR;

	spin_lock_irqsave(&hp->lock, flags);

	new_mctrl = (hp->mctrl & ~clear) | set;

	if (hp->mctrl != new_mctrl) {
		hvsi_set_mctrl(hp, new_mctrl);
		hp->mctrl = new_mctrl;
	}
	spin_unlock_irqrestore(&hp->lock, flags);

	return 0;
}


static struct tty_operations hvsi_ops = {
	.open = hvsi_open,
	.close = hvsi_close,
	.write = hvsi_write,
	.hangup = hvsi_hangup,
	.write_room = hvsi_write_room,
	.chars_in_buffer = hvsi_chars_in_buffer,
	.throttle = hvsi_throttle,
	.unthrottle = hvsi_unthrottle,
	.tiocmget = hvsi_tiocmget,
	.tiocmset = hvsi_tiocmset,
};

static int __init hvsi_init(void)
{
	int i;

	hvsi_driver = alloc_tty_driver(hvsi_count);
	if (!hvsi_driver)
		return -ENOMEM;

	hvsi_driver->owner = THIS_MODULE;
	hvsi_driver->devfs_name = "hvsi/";
	hvsi_driver->driver_name = "hvsi";
	hvsi_driver->name = "hvsi";
	hvsi_driver->major = HVSI_MAJOR;
	hvsi_driver->minor_start = HVSI_MINOR;
	hvsi_driver->type = TTY_DRIVER_TYPE_SYSTEM;
	hvsi_driver->init_termios = tty_std_termios;
	hvsi_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
	hvsi_driver->flags = TTY_DRIVER_REAL_RAW;
	tty_set_operations(hvsi_driver, &hvsi_ops);

	for (i=0; i < hvsi_count; i++) {
		struct hvsi_struct *hp = &hvsi_ports[i];
		int ret = 1;

		ret = request_irq(hp->virq, hvsi_interrupt, SA_INTERRUPT, "hvsi", hp);
		if (ret)
			printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
				hp->virq, ret);
	}
	hvsi_wait = wait_for_state; /* irqs active now */

	if (tty_register_driver(hvsi_driver))
		panic("Couldn't register hvsi console driver\n");

	printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);

	return 0;
}
device_initcall(hvsi_init);

/***** console (not tty) code: *****/

static void hvsi_console_print(struct console *console, const char *buf,
		unsigned int count)
{
	struct hvsi_struct *hp = &hvsi_ports[console->index];
	char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
	unsigned int i = 0, n = 0;
	int ret, donecr = 0;

	mb();
	if (!is_open(hp))
		return;

	/*
	 * ugh, we have to translate LF -> CRLF ourselves, in place.
	 * copied from hvc_console.c:
	 */
	while (count > 0 || i > 0) {
		if (count > 0 && i < sizeof(c)) {
			if (buf[n] == '\n' && !donecr) {
				c[i++] = '\r';
				donecr = 1;
			} else {
				c[i++] = buf[n++];
				donecr = 0;
				--count;
			}
		} else {
			ret = hvsi_put_chars(hp, c, i);
			if (ret < 0)
				i = 0;
			i -= ret;
		}
	}
}

static struct tty_driver *hvsi_console_device(struct console *console,
	int *index)
{
	*index = console->index;
	return hvsi_driver;
}

static int __init hvsi_console_setup(struct console *console, char *options)
{
	struct hvsi_struct *hp = &hvsi_ports[console->index];
	int ret;

	if (console->index < 0 || console->index >= hvsi_count)
		return -1;

	/* give the FSP a chance to change the baud rate when we re-open */
	hvsi_close_protocol(hp);

	ret = hvsi_handshake(hp);
	if (ret < 0)
		return ret;

	ret = hvsi_get_mctrl(hp);
	if (ret < 0)
		return ret;

	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
	if (ret < 0)
		return ret;

	hp->flags |= HVSI_CONSOLE;

	return 0;
}

static struct console hvsi_con_driver = {
	.name		= "hvsi",
	.write		= hvsi_console_print,
	.device		= hvsi_console_device,
	.setup		= hvsi_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
};

static int __init hvsi_console_init(void)
{
	struct device_node *vty;

	hvsi_wait = poll_for_state; /* no irqs yet; must poll */

	/* search device tree for vty nodes */
	for (vty = of_find_compatible_node(NULL, "serial", "hvterm-protocol");
			vty != NULL;
			vty = of_find_compatible_node(vty, "serial", "hvterm-protocol")) {
		struct hvsi_struct *hp;
		uint32_t *vtermno;
		uint32_t *irq;

		vtermno = (uint32_t *)get_property(vty, "reg", NULL);
		irq = (uint32_t *)get_property(vty, "interrupts", NULL);
		if (!vtermno || !irq)
			continue;

		if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
			of_node_put(vty);
			break;
		}

		hp = &hvsi_ports[hvsi_count];
		INIT_WORK(&hp->writer, hvsi_write_worker, hp);
		INIT_WORK(&hp->handshaker, hvsi_handshaker, hp);
		init_waitqueue_head(&hp->emptyq);
		init_waitqueue_head(&hp->stateq);
		spin_lock_init(&hp->lock);
		hp->index = hvsi_count;
		hp->inbuf_end = hp->inbuf;
		hp->state = HVSI_CLOSED;
		hp->vtermno = *vtermno;
		hp->virq = virt_irq_create_mapping(irq[0]);
		if (hp->virq == NO_IRQ) {
			printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
				__FUNCTION__, hp->virq);
			continue;
		} else
			hp->virq = irq_offset_up(hp->virq);

		hvsi_count++;
	}

	if (hvsi_count)
		register_console(&hvsi_con_driver);
	return 0;
}
console_initcall(hvsi_console_init);