summaryrefslogtreecommitdiffstats
path: root/drivers/char/viocons.c
blob: 7feeb774a10152e29ae13ce0f635403a2f90a65e (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
/* -*- linux-c -*-
 *
 *  drivers/char/viocons.c
 *
 *  iSeries Virtual Terminal
 *
 *  Authors: Dave Boutcher <boutcher@us.ibm.com>
 *           Ryan Arnold <ryanarn@us.ibm.com>
 *           Colin Devilbiss <devilbis@us.ibm.com>
 *           Stephen Rothwell
 *
 * (C) Copyright 2000, 2001, 2002, 2003, 2004 IBM Corporation
 *
 * 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) anyu 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
 */
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/errno.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/console.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <asm/ioctls.h>
#include <linux/kd.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/sysrq.h>

#include <asm/firmware.h>
#include <asm/iseries/vio.h>
#include <asm/iseries/hv_lp_event.h>
#include <asm/iseries/hv_call_event.h>
#include <asm/iseries/hv_lp_config.h>
#include <asm/iseries/hv_call.h>

#ifdef CONFIG_VT
#error You must turn off CONFIG_VT to use CONFIG_VIOCONS
#endif

#define VIOTTY_MAGIC (0x0DCB)
#define VTTY_PORTS 10

#define VIOCONS_KERN_WARN	KERN_WARNING "viocons: "
#define VIOCONS_KERN_INFO	KERN_INFO "viocons: "

static DEFINE_SPINLOCK(consolelock);
static DEFINE_SPINLOCK(consoleloglock);

static int vio_sysrq_pressed;

#define VIOCHAR_NUM_BUF		16

/*
 * Our port information.  We store a pointer to one entry in the
 * tty_driver_data
 */
static struct port_info {
	int magic;
	struct tty_struct *tty;
	HvLpIndex lp;
	u8 vcons;
	u64 seq;	/* sequence number of last HV send */
	u64 ack;	/* last ack from HV */
/*
 * When we get writes faster than we can send it to the partition,
 * buffer the data here. Note that used is a bit map of used buffers.
 * It had better have enough bits to hold VIOCHAR_NUM_BUF the bitops assume
 * it is a multiple of unsigned long
 */
	unsigned long used;
	u8 *buffer[VIOCHAR_NUM_BUF];
	int bufferBytes[VIOCHAR_NUM_BUF];
	int curbuf;
	int bufferOverflow;
	int overflowMessage;
} port_info[VTTY_PORTS];

#define viochar_is_console(pi)	((pi) == &port_info[0])
#define viochar_port(pi)	((pi) - &port_info[0])

static void initDataEvent(struct viocharlpevent *viochar, HvLpIndex lp);

static struct tty_driver *viotty_driver;

static void hvlog(char *fmt, ...)
{
	int i;
	unsigned long flags;
	va_list args;
	static char buf[256];

	spin_lock_irqsave(&consoleloglock, flags);
	va_start(args, fmt);
	i = vscnprintf(buf, sizeof(buf) - 1, fmt, args);
	va_end(args);
	buf[i++] = '\r';
	HvCall_writeLogBuffer(buf, i);
	spin_unlock_irqrestore(&consoleloglock, flags);
}

static void hvlogOutput(const char *buf, int count)
{
	unsigned long flags;
	int begin;
	int index;
	static const char cr = '\r';

	begin = 0;
	spin_lock_irqsave(&consoleloglock, flags);
	for (index = 0; index < count; index++) {
		if (buf[index] == '\n') {
			/*
			 * Start right after the last '\n' or at the zeroth
			 * array position and output the number of characters
			 * including the newline.
			 */
			HvCall_writeLogBuffer(&buf[begin], index - begin + 1);
			begin = index + 1;
			HvCall_writeLogBuffer(&cr, 1);
		}
	}
	if ((index - begin) > 0)
		HvCall_writeLogBuffer(&buf[begin], index - begin);
	spin_unlock_irqrestore(&consoleloglock, flags);
}

/*
 * Make sure we're pointing to a valid port_info structure.  Shamelessly
 * plagerized from serial.c
 */
static inline int viotty_paranoia_check(struct port_info *pi,
					char *name, const char *routine)
{
	static const char *bad_pi_addr = VIOCONS_KERN_WARN
		"warning: bad address for port_info struct (%s) in %s\n";
	static const char *badmagic = VIOCONS_KERN_WARN
		"warning: bad magic number for port_info struct (%s) in %s\n";

	if ((pi < &port_info[0]) || (viochar_port(pi) > VTTY_PORTS)) {
		printk(bad_pi_addr, name, routine);
		return 1;
	}
	if (pi->magic != VIOTTY_MAGIC) {
		printk(badmagic, name, routine);
		return 1;
	}
	return 0;
}

/*
 * Add data to our pending-send buffers.  
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.
 * hvlog can be used to log to the hypervisor buffer
 */
static int buffer_add(struct port_info *pi, const char *buf, size_t len)
{
	size_t bleft;
	size_t curlen;
	const char *curbuf;
	int nextbuf;

	curbuf = buf;
	bleft = len;
	while (bleft > 0) {
		/*
		 * If there is no space left in the current buffer, we have
		 * filled everything up, so return.  If we filled the previous
		 * buffer we would already have moved to the next one.
		 */
		if (pi->bufferBytes[pi->curbuf] == VIOCHAR_MAX_DATA) {
			hvlog ("\n\rviocons: No overflow buffer available for memcpy().\n");
			pi->bufferOverflow++;
			pi->overflowMessage = 1;
			break;
		}

		/*
		 * Turn on the "used" bit for this buffer.  If it's already on,
		 * that's fine.
		 */
		set_bit(pi->curbuf, &pi->used);

		/*
		 * See if this buffer has been allocated.  If not, allocate it.
		 */
		if (pi->buffer[pi->curbuf] == NULL) {
			pi->buffer[pi->curbuf] =
			    kmalloc(VIOCHAR_MAX_DATA, GFP_ATOMIC);
			if (pi->buffer[pi->curbuf] == NULL) {
				hvlog("\n\rviocons: kmalloc failed allocating spaces for buffer %d.",
					pi->curbuf);
				break;
			}
		}

		/* Figure out how much we can copy into this buffer. */
		if (bleft < (VIOCHAR_MAX_DATA - pi->bufferBytes[pi->curbuf]))
			curlen = bleft;
		else
			curlen = VIOCHAR_MAX_DATA - pi->bufferBytes[pi->curbuf];

		/* Copy the data into the buffer. */
		memcpy(pi->buffer[pi->curbuf] + pi->bufferBytes[pi->curbuf],
				curbuf, curlen);

		pi->bufferBytes[pi->curbuf] += curlen;
		curbuf += curlen;
		bleft -= curlen;

		/*
		 * Now see if we've filled this buffer.  If not then
		 * we'll try to use it again later.  If we've filled it
		 * up then we'll advance the curbuf to the next in the
		 * circular queue.
		 */
		if (pi->bufferBytes[pi->curbuf] == VIOCHAR_MAX_DATA) {
			nextbuf = (pi->curbuf + 1) % VIOCHAR_NUM_BUF;
			/*
			 * Move to the next buffer if it hasn't been used yet
			 */
			if (test_bit(nextbuf, &pi->used) == 0)
				pi->curbuf = nextbuf;
		}
	}
	return len - bleft;
}

/*
 * Send pending data
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.
 * hvlog can be used to log to the hypervisor buffer
 */
static void send_buffers(struct port_info *pi)
{
	HvLpEvent_Rc hvrc;
	int nextbuf;
	struct viocharlpevent *viochar;
	unsigned long flags;

	spin_lock_irqsave(&consolelock, flags);

	viochar = (struct viocharlpevent *)
	    vio_get_event_buffer(viomajorsubtype_chario);

	/* Make sure we got a buffer */
	if (viochar == NULL) {
		hvlog("\n\rviocons: Can't get viochar buffer in sendBuffers().");
		spin_unlock_irqrestore(&consolelock, flags);
		return;
	}

	if (pi->used == 0) {
		hvlog("\n\rviocons: in sendbuffers(), but no buffers used.\n");
		vio_free_event_buffer(viomajorsubtype_chario, viochar);
		spin_unlock_irqrestore(&consolelock, flags);
		return;
	}

	/*
	 * curbuf points to the buffer we're filling.  We want to
	 * start sending AFTER this one.  
	 */
	nextbuf = (pi->curbuf + 1) % VIOCHAR_NUM_BUF;

	/*
	 * Loop until we find a buffer with the used bit on
	 */
	while (test_bit(nextbuf, &pi->used) == 0)
		nextbuf = (nextbuf + 1) % VIOCHAR_NUM_BUF;

	initDataEvent(viochar, pi->lp);

	/*
	 * While we have buffers with data, and our send window
	 * is open, send them
	 */
	while ((test_bit(nextbuf, &pi->used)) &&
	       ((pi->seq - pi->ack) < VIOCHAR_WINDOW)) {
		viochar->len = pi->bufferBytes[nextbuf];
		viochar->event.xCorrelationToken = pi->seq++;
		viochar->event.xSizeMinus1 =
			offsetof(struct viocharlpevent, data) + viochar->len;

		memcpy(viochar->data, pi->buffer[nextbuf], viochar->len);

		hvrc = HvCallEvent_signalLpEvent(&viochar->event);
		if (hvrc) {
			/*
			 * MUST unlock the spinlock before doing a printk
			 */
			vio_free_event_buffer(viomajorsubtype_chario, viochar);
			spin_unlock_irqrestore(&consolelock, flags);

			printk(VIOCONS_KERN_WARN
			       "error sending event! return code %d\n",
			       (int)hvrc);
			return;
		}

		/*
		 * clear the used bit, zero the number of bytes in
		 * this buffer, and move to the next buffer
		 */
		clear_bit(nextbuf, &pi->used);
		pi->bufferBytes[nextbuf] = 0;
		nextbuf = (nextbuf + 1) % VIOCHAR_NUM_BUF;
	}

	/*
	 * If we have emptied all the buffers, start at 0 again.
	 * this will re-use any allocated buffers
	 */
	if (pi->used == 0) {
		pi->curbuf = 0;

		if (pi->overflowMessage)
			pi->overflowMessage = 0;

		if (pi->tty) {
			tty_wakeup(pi->tty);
		}
	}

	vio_free_event_buffer(viomajorsubtype_chario, viochar);
	spin_unlock_irqrestore(&consolelock, flags);
}

/*
 * Our internal writer.  Gets called both from the console device and
 * the tty device.  the tty pointer will be NULL if called from the console.
 * Return total number of bytes "written".
 *
 * NOTE: Don't use printk in here because it gets nastily recursive.  hvlog
 * can be used to log to the hypervisor buffer
 */
static int internal_write(struct port_info *pi, const char *buf, size_t len)
{
	HvLpEvent_Rc hvrc;
	size_t bleft;
	size_t curlen;
	const char *curbuf;
	unsigned long flags;
	struct viocharlpevent *viochar;

	/*
	 * Write to the hvlog of inbound data are now done prior to
	 * calling internal_write() since internal_write() is only called in
	 * the event that an lp event path is active, which isn't the case for
	 * logging attempts prior to console initialization.
	 *
	 * If there is already data queued for this port, send it prior to
	 * attempting to send any new data.
	 */
	if (pi->used)
		send_buffers(pi);

	spin_lock_irqsave(&consolelock, flags);

	viochar = vio_get_event_buffer(viomajorsubtype_chario);
	if (viochar == NULL) {
		spin_unlock_irqrestore(&consolelock, flags);
		hvlog("\n\rviocons: Can't get vio buffer in internal_write().");
		return -EAGAIN;
	}
	initDataEvent(viochar, pi->lp);

	curbuf = buf;
	bleft = len;

	while ((bleft > 0) && (pi->used == 0) &&
	       ((pi->seq - pi->ack) < VIOCHAR_WINDOW)) {
		if (bleft > VIOCHAR_MAX_DATA)
			curlen = VIOCHAR_MAX_DATA;
		else
			curlen = bleft;

		viochar->event.xCorrelationToken = pi->seq++;
		memcpy(viochar->data, curbuf, curlen);
		viochar->len = curlen;
		viochar->event.xSizeMinus1 =
		    offsetof(struct viocharlpevent, data) + curlen;

		hvrc = HvCallEvent_signalLpEvent(&viochar->event);
		if (hvrc) {
			hvlog("viocons: error sending event! %d\n", (int)hvrc);
			goto out;
		}
		curbuf += curlen;
		bleft -= curlen;
	}

	/* If we didn't send it all, buffer as much of it as we can. */
	if (bleft > 0)
		bleft -= buffer_add(pi, curbuf, bleft);
out:
	vio_free_event_buffer(viomajorsubtype_chario, viochar);
	spin_unlock_irqrestore(&consolelock, flags);
	return len - bleft;
}

static struct port_info *get_port_data(struct tty_struct *tty)
{
	unsigned long flags;
	struct port_info *pi;

	spin_lock_irqsave(&consolelock, flags);
	if (tty) {
		pi = (struct port_info *)tty->driver_data;
		if (!pi || viotty_paranoia_check(pi, tty->name,
					     "get_port_data")) {
			pi = NULL;
		}
	} else
		/*
		 * If this is the console device, use the lp from
		 * the first port entry
		 */
		pi = &port_info[0];
	spin_unlock_irqrestore(&consolelock, flags);
	return pi;
}

/*
 * Initialize the common fields in a charLpEvent
 */
static void initDataEvent(struct viocharlpevent *viochar, HvLpIndex lp)
{
	struct HvLpEvent *hev = &viochar->event;

	memset(viochar, 0, sizeof(struct viocharlpevent));

	hev->flags = HV_LP_EVENT_VALID | HV_LP_EVENT_DEFERRED_ACK |
		HV_LP_EVENT_INT;
	hev->xType = HvLpEvent_Type_VirtualIo;
	hev->xSubtype = viomajorsubtype_chario | viochardata;
	hev->xSourceLp = HvLpConfig_getLpIndex();
	hev->xTargetLp = lp;
	hev->xSizeMinus1 = sizeof(struct viocharlpevent);
	hev->xSourceInstanceId = viopath_sourceinst(lp);
	hev->xTargetInstanceId = viopath_targetinst(lp);
}

/*
 * early console device write
 */
static void viocons_write_early(struct console *co, const char *s, unsigned count)
{
	hvlogOutput(s, count);
}

/*
 * console device write
 */
static void viocons_write(struct console *co, const char *s, unsigned count)
{
	int index;
	int begin;
	struct port_info *pi;

	static const char cr = '\r';

	/*
	 * Check port data first because the target LP might be valid but
	 * simply not active, in which case we want to hvlog the output.
	 */
	pi = get_port_data(NULL);
	if (pi == NULL) {
		hvlog("\n\rviocons_write: unable to get port data.");
		return;
	}

	hvlogOutput(s, count);

	if (!viopath_isactive(pi->lp))
		return;

	/* 
	 * Any newline character found will cause a
	 * carriage return character to be emitted as well. 
	 */
	begin = 0;
	for (index = 0; index < count; index++) {
		if (s[index] == '\n') {
			/* 
			 * Newline found. Print everything up to and 
			 * including the newline
			 */
			internal_write(pi, &s[begin], index - begin + 1);
			begin = index + 1;
			/* Emit a carriage return as well */
			internal_write(pi, &cr, 1);
		}
	}

	/* If any characters left to write, write them now */
	if ((index - begin) > 0)
		internal_write(pi, &s[begin], index - begin);
}

/*
 * Work out the device associate with this console
 */
static struct tty_driver *viocons_device(struct console *c, int *index)
{
	*index = c->index;
	return viotty_driver;
}

/*
 * console device I/O methods
 */
static struct console viocons_early = {
	.name = "viocons",
	.write = viocons_write_early,
	.flags = CON_PRINTBUFFER,
	.index = -1,
};

static struct console viocons = {
	.name = "viocons",
	.write = viocons_write,
	.device = viocons_device,
	.flags = CON_PRINTBUFFER,
	.index = -1,
};

/*
 * TTY Open method
 */
static int viotty_open(struct tty_struct *tty, struct file *filp)
{
	int port;
	unsigned long flags;
	struct port_info *pi;

	port = tty->index;

	if ((port < 0) || (port >= VTTY_PORTS))
		return -ENODEV;

	spin_lock_irqsave(&consolelock, flags);

	pi = &port_info[port];
	/* If some other TTY is already connected here, reject the open */
	if ((pi->tty) && (pi->tty != tty)) {
		spin_unlock_irqrestore(&consolelock, flags);
		printk(VIOCONS_KERN_WARN
		       "attempt to open device twice from different ttys\n");
		return -EBUSY;
	}
	tty->driver_data = pi;
	pi->tty = tty;
	spin_unlock_irqrestore(&consolelock, flags);

	return 0;
}

/*
 * TTY Close method
 */
static void viotty_close(struct tty_struct *tty, struct file *filp)
{
	unsigned long flags;
	struct port_info *pi;

	spin_lock_irqsave(&consolelock, flags);
	pi = (struct port_info *)tty->driver_data;

	if (!pi || viotty_paranoia_check(pi, tty->name, "viotty_close")) {
		spin_unlock_irqrestore(&consolelock, flags);
		return;
	}
	if (tty->count == 1)
		pi->tty = NULL;
	spin_unlock_irqrestore(&consolelock, flags);
}

/*
 * TTY Write method
 */
static int viotty_write(struct tty_struct *tty, const unsigned char *buf,
		int count)
{
	struct port_info *pi;

	pi = get_port_data(tty);
	if (pi == NULL) {
		hvlog("\n\rviotty_write: no port data.");
		return -ENODEV;
	}

	if (viochar_is_console(pi))
		hvlogOutput(buf, count);

	/*
	 * If the path to this LP is closed, don't bother doing anything more.
	 * just dump the data on the floor and return count.  For some reason
	 * some user level programs will attempt to probe available tty's and
	 * they'll attempt a viotty_write on an invalid port which maps to an
	 * invalid target lp.  If this is the case then ignore the
	 * viotty_write call and, since the viopath isn't active to this
	 * partition, return count.
	 */
	if (!viopath_isactive(pi->lp))
		return count;

	return internal_write(pi, buf, count);
}

/*
 * TTY put_char method
 */
static int viotty_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct port_info *pi;

	pi = get_port_data(tty);
	if (pi == NULL)
		return 0;

	/* This will append '\r' as well if the char is '\n' */
	if (viochar_is_console(pi))
		hvlogOutput(&ch, 1);

	if (viopath_isactive(pi->lp))
		internal_write(pi, &ch, 1);
	return 1;
}

/*
 * TTY write_room method
 */
static int viotty_write_room(struct tty_struct *tty)
{
	int i;
	int room = 0;
	struct port_info *pi;
	unsigned long flags;

	spin_lock_irqsave(&consolelock, flags);
	pi = (struct port_info *)tty->driver_data;
	if (!pi || viotty_paranoia_check(pi, tty->name, "viotty_write_room")) {
		spin_unlock_irqrestore(&consolelock, flags);
		return 0;
	}

	/* If no buffers are used, return the max size. */
	if (pi->used == 0) {
		spin_unlock_irqrestore(&consolelock, flags);
		return VIOCHAR_MAX_DATA * VIOCHAR_NUM_BUF;
	}

	/*
	 * We retain the spinlock because we want to get an accurate
	 * count and it can change on us between each operation if we
	 * don't hold the spinlock.
	 */
	for (i = 0; ((i < VIOCHAR_NUM_BUF) && (room < VIOCHAR_MAX_DATA)); i++)
		room += (VIOCHAR_MAX_DATA - pi->bufferBytes[i]);
	spin_unlock_irqrestore(&consolelock, flags);

	if (room > VIOCHAR_MAX_DATA)
		room = VIOCHAR_MAX_DATA;
	return room;
}

/*
 * TTY chars_in_buffer method
 */
static int viotty_chars_in_buffer(struct tty_struct *tty)
{
	return 0;
}

static int viotty_ioctl(struct tty_struct *tty, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	/*
	 * the ioctls below read/set the flags usually shown in the leds
	 * don't use them - they will go away without warning
	 */
	case KDGETLED:
	case KDGKBLED:
		return put_user(0, (char *)arg);

	case KDSKBLED:
		return 0;
	}
	return -ENOIOCTLCMD;
}

/*
 * Handle an open charLpEvent.  Could be either interrupt or ack
 */
static void vioHandleOpenEvent(struct HvLpEvent *event)
{
	unsigned long flags;
	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
	u8 port = cevent->virtual_device;
	struct port_info *pi;
	int reject = 0;

	if (hvlpevent_is_ack(event)) {
		if (port >= VTTY_PORTS)
			return;

		spin_lock_irqsave(&consolelock, flags);
		/* Got the lock, don't cause console output */

		pi = &port_info[port];
		if (event->xRc == HvLpEvent_Rc_Good) {
			pi->seq = pi->ack = 0;
			/*
			 * This line allows connections from the primary
			 * partition but once one is connected from the
			 * primary partition nothing short of a reboot
			 * of linux will allow access from the hosting
			 * partition again without a required iSeries fix.
			 */
			pi->lp = event->xTargetLp;
		}

		spin_unlock_irqrestore(&consolelock, flags);
		if (event->xRc != HvLpEvent_Rc_Good)
			printk(VIOCONS_KERN_WARN
			       "handle_open_event: event->xRc == (%d).\n",
			       event->xRc);

		if (event->xCorrelationToken != 0) {
			atomic_t *aptr= (atomic_t *)event->xCorrelationToken;
			atomic_set(aptr, 1);
		} else
			printk(VIOCONS_KERN_WARN
			       "weird...got open ack without atomic\n");
		return;
	}

	/* This had better require an ack, otherwise complain */
	if (!hvlpevent_need_ack(event)) {
		printk(VIOCONS_KERN_WARN "viocharopen without ack bit!\n");
		return;
	}

	spin_lock_irqsave(&consolelock, flags);
	/* Got the lock, don't cause console output */

	/* Make sure this is a good virtual tty */
	if (port >= VTTY_PORTS) {
		event->xRc = HvLpEvent_Rc_SubtypeError;
		cevent->subtype_result_code = viorc_openRejected;
		/*
		 * Flag state here since we can't printk while holding
		 * a spinlock.
		 */
		reject = 1;
	} else {
		pi = &port_info[port];
		if ((pi->lp != HvLpIndexInvalid) &&
				(pi->lp != event->xSourceLp)) {
			/*
			 * If this is tty is already connected to a different
			 * partition, fail.
			 */
			event->xRc = HvLpEvent_Rc_SubtypeError;
			cevent->subtype_result_code = viorc_openRejected;
			reject = 2;
		} else {
			pi->lp = event->xSourceLp;
			event->xRc = HvLpEvent_Rc_Good;
			cevent->subtype_result_code = viorc_good;
			pi->seq = pi->ack = 0;
			reject = 0;
		}
	}

	spin_unlock_irqrestore(&consolelock, flags);

	if (reject == 1)
		printk(VIOCONS_KERN_WARN "open rejected: bad virtual tty.\n");
	else if (reject == 2)
		printk(VIOCONS_KERN_WARN
			"open rejected: console in exclusive use by another partition.\n");

	/* Return the acknowledgement */
	HvCallEvent_ackLpEvent(event);
}

/*
 * Handle a close charLpEvent.  This should ONLY be an Interrupt because the
 * virtual console should never actually issue a close event to the hypervisor
 * because the virtual console never goes away.  A close event coming from the
 * hypervisor simply means that there are no client consoles connected to the
 * virtual console.
 *
 * Regardless of the number of connections masqueraded on the other side of
 * the hypervisor ONLY ONE close event should be called to accompany the ONE
 * open event that is called.  The close event should ONLY be called when NO
 * MORE connections (masqueraded or not) exist on the other side of the
 * hypervisor.
 */
static void vioHandleCloseEvent(struct HvLpEvent *event)
{
	unsigned long flags;
	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
	u8 port = cevent->virtual_device;

	if (hvlpevent_is_int(event)) {
		if (port >= VTTY_PORTS) {
			printk(VIOCONS_KERN_WARN
					"close message from invalid virtual device.\n");
			return;
		}

		/* For closes, just mark the console partition invalid */
		spin_lock_irqsave(&consolelock, flags);
		/* Got the lock, don't cause console output */

		if (port_info[port].lp == event->xSourceLp)
			port_info[port].lp = HvLpIndexInvalid;

		spin_unlock_irqrestore(&consolelock, flags);
		printk(VIOCONS_KERN_INFO "close from %d\n", event->xSourceLp);
	} else
		printk(VIOCONS_KERN_WARN
				"got unexpected close acknowlegement\n");
}

/*
 * Handle a config charLpEvent.  Could be either interrupt or ack
 */
static void vioHandleConfig(struct HvLpEvent *event)
{
	struct viocharlpevent *cevent = (struct viocharlpevent *)event;

	HvCall_writeLogBuffer(cevent->data, cevent->len);

	if (cevent->data[0] == 0x01)
		printk(VIOCONS_KERN_INFO "window resized to %d: %d: %d: %d\n",
		       cevent->data[1], cevent->data[2],
		       cevent->data[3], cevent->data[4]);
	else
		printk(VIOCONS_KERN_WARN "unknown config event\n");
}

/*
 * Handle a data charLpEvent. 
 */
static void vioHandleData(struct HvLpEvent *event)
{
	struct tty_struct *tty;
	unsigned long flags;
	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
	struct port_info *pi;
	int index;
	int num_pushed;
	u8 port = cevent->virtual_device;

	if (port >= VTTY_PORTS) {
		printk(VIOCONS_KERN_WARN "data on invalid virtual device %d\n",
				port);
		return;
	}

	/*
	 * Hold the spinlock so that we don't take an interrupt that
	 * changes tty between the time we fetch the port_info
	 * pointer and the time we paranoia check.
	 */
	spin_lock_irqsave(&consolelock, flags);
	pi = &port_info[port];

	/*
	 * Change 05/01/2003 - Ryan Arnold: If a partition other than
	 * the current exclusive partition tries to send us data
	 * events then just drop them on the floor because we don't
	 * want his stinking data.  He isn't authorized to receive
	 * data because he wasn't the first one to get the console,
	 * therefore he shouldn't be allowed to send data either.
	 * This will work without an iSeries fix.
	 */
	if (pi->lp != event->xSourceLp) {
		spin_unlock_irqrestore(&consolelock, flags);
		return;
	}

	tty = pi->tty;
	if (tty == NULL) {
		spin_unlock_irqrestore(&consolelock, flags);
		printk(VIOCONS_KERN_WARN "no tty for virtual device %d\n",
				port);
		return;
	}

	if (tty->magic != TTY_MAGIC) {
		spin_unlock_irqrestore(&consolelock, flags);
		printk(VIOCONS_KERN_WARN "tty bad magic\n");
		return;
	}

	/*
	 * Just to be paranoid, make sure the tty points back to this port
	 */
	pi = (struct port_info *)tty->driver_data;
	if (!pi || viotty_paranoia_check(pi, tty->name, "vioHandleData")) {
		spin_unlock_irqrestore(&consolelock, flags);
		return;
	}
	spin_unlock_irqrestore(&consolelock, flags);

	/*
	 * Change 07/21/2003 - Ryan Arnold: functionality added to
	 * support sysrq utilizing ^O as the sysrq key.  The sysrq
	 * functionality will only work if built into the kernel and
	 * then only if sysrq is enabled through the proc filesystem.
	 */
	num_pushed = 0;
	for (index = 0; index < cevent->len; index++) {
		/*
		 * Will be optimized away if !CONFIG_MAGIC_SYSRQ:
		 */
		if (sysrq_on()) {
			/* 0x0f is the ascii character for ^O */
			if (cevent->data[index] == '\x0f') {
				vio_sysrq_pressed = 1;
				/*
				 * continue because we don't want to add
				 * the sysrq key into the data string.
				 */
				continue;
			} else if (vio_sysrq_pressed) {
				handle_sysrq(cevent->data[index], tty);
				vio_sysrq_pressed = 0;
				/*
				 * continue because we don't want to add
				 * the sysrq sequence into the data string.
				 */
				continue;
			}
		}
		/*
		 * The sysrq sequence isn't included in this check if
		 * sysrq is enabled and compiled into the kernel because
		 * the sequence will never get inserted into the buffer.
		 * Don't attempt to copy more data into the buffer than we
		 * have room for because it would fail without indication.
		 */
		if(tty_insert_flip_char(tty, cevent->data[index], TTY_NORMAL) == 0) {
			printk(VIOCONS_KERN_WARN "input buffer overflow!\n");
			break;
		}
		num_pushed++;
	}

	if (num_pushed)
		tty_flip_buffer_push(tty);
}

/*
 * Handle an ack charLpEvent. 
 */
static void vioHandleAck(struct HvLpEvent *event)
{
	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
	unsigned long flags;
	u8 port = cevent->virtual_device;

	if (port >= VTTY_PORTS) {
		printk(VIOCONS_KERN_WARN "data on invalid virtual device\n");
		return;
	}

	spin_lock_irqsave(&consolelock, flags);
	port_info[port].ack = event->xCorrelationToken;
	spin_unlock_irqrestore(&consolelock, flags);

	if (port_info[port].used)
		send_buffers(&port_info[port]);
}

/*
 * Handle charLpEvents and route to the appropriate routine
 */
static void vioHandleCharEvent(struct HvLpEvent *event)
{
	int charminor;

	if (event == NULL)
		return;

	charminor = event->xSubtype & VIOMINOR_SUBTYPE_MASK;
	switch (charminor) {
	case viocharopen:
		vioHandleOpenEvent(event);
		break;
	case viocharclose:
		vioHandleCloseEvent(event);
		break;
	case viochardata:
		vioHandleData(event);
		break;
	case viocharack:
		vioHandleAck(event);
		break;
	case viocharconfig:
		vioHandleConfig(event);
		break;
	default:
		if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
			event->xRc = HvLpEvent_Rc_InvalidSubtype;
			HvCallEvent_ackLpEvent(event);
		}
	}
}

/*
 * Send an open event
 */
static int send_open(HvLpIndex remoteLp, void *sem)
{
	return HvCallEvent_signalLpEventFast(remoteLp,
			HvLpEvent_Type_VirtualIo,
			viomajorsubtype_chario | viocharopen,
			HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
			viopath_sourceinst(remoteLp),
			viopath_targetinst(remoteLp),
			(u64)(unsigned long)sem, VIOVERSION << 16,
			0, 0, 0, 0);
}

static const struct tty_operations serial_ops = {
	.open = viotty_open,
	.close = viotty_close,
	.write = viotty_write,
	.put_char = viotty_put_char,
	.write_room = viotty_write_room,
	.chars_in_buffer = viotty_chars_in_buffer,
	.ioctl = viotty_ioctl,
};

static int __init viocons_init2(void)
{
	atomic_t wait_flag;
	int rc;

	if (!firmware_has_feature(FW_FEATURE_ISERIES))
		return -ENODEV;

	/* +2 for fudge */
	rc = viopath_open(HvLpConfig_getPrimaryLpIndex(),
			viomajorsubtype_chario, VIOCHAR_WINDOW + 2);
	if (rc)
		printk(VIOCONS_KERN_WARN "error opening to primary %d\n", rc);

	if (viopath_hostLp == HvLpIndexInvalid)
		vio_set_hostlp();

	/*
	 * And if the primary is not the same as the hosting LP, open to the 
	 * hosting lp
	 */
	if ((viopath_hostLp != HvLpIndexInvalid) &&
	    (viopath_hostLp != HvLpConfig_getPrimaryLpIndex())) {
		printk(VIOCONS_KERN_INFO "open path to hosting (%d)\n",
				viopath_hostLp);
		rc = viopath_open(viopath_hostLp, viomajorsubtype_chario,
				VIOCHAR_WINDOW + 2);	/* +2 for fudge */
		if (rc)
			printk(VIOCONS_KERN_WARN
				"error opening to partition %d: %d\n",
				viopath_hostLp, rc);
	}

	if (vio_setHandler(viomajorsubtype_chario, vioHandleCharEvent) < 0)
		printk(VIOCONS_KERN_WARN
				"error seting handler for console events!\n");

	/*
	 * First, try to open the console to the hosting lp.
	 * Wait on a semaphore for the response.
	 */
	atomic_set(&wait_flag, 0);
	if ((viopath_isactive(viopath_hostLp)) &&
	    (send_open(viopath_hostLp, (void *)&wait_flag) == 0)) {
		printk(VIOCONS_KERN_INFO "hosting partition %d\n",
			viopath_hostLp);
		while (atomic_read(&wait_flag) == 0)
			mb();
		atomic_set(&wait_flag, 0);
	}

	/*
	 * If we don't have an active console, try the primary
	 */
	if ((!viopath_isactive(port_info[0].lp)) &&
	    (viopath_isactive(HvLpConfig_getPrimaryLpIndex())) &&
	    (send_open(HvLpConfig_getPrimaryLpIndex(), (void *)&wait_flag)
	     == 0)) {
		printk(VIOCONS_KERN_INFO "opening console to primary partition\n");
		while (atomic_read(&wait_flag) == 0)
			mb();
	}

	/* Initialize the tty_driver structure */
	viotty_driver = alloc_tty_driver(VTTY_PORTS);
	viotty_driver->owner = THIS_MODULE;
	viotty_driver->driver_name = "vioconsole";
	viotty_driver->name = "tty";
	viotty_driver->name_base = 1;
	viotty_driver->major = TTY_MAJOR;
	viotty_driver->minor_start = 1;
	viotty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
	viotty_driver->subtype = 1;
	viotty_driver->init_termios = tty_std_termios;
	viotty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
	tty_set_operations(viotty_driver, &serial_ops);

	if (tty_register_driver(viotty_driver)) {
		printk(VIOCONS_KERN_WARN "couldn't register console driver\n");
		put_tty_driver(viotty_driver);
		viotty_driver = NULL;
	}

	unregister_console(&viocons_early);
	register_console(&viocons);

	return 0;
}

static int __init viocons_init(void)
{
	int i;

	if (!firmware_has_feature(FW_FEATURE_ISERIES))
		return -ENODEV;

	printk(VIOCONS_KERN_INFO "registering console\n");
	for (i = 0; i < VTTY_PORTS; i++) {
		port_info[i].lp = HvLpIndexInvalid;
		port_info[i].magic = VIOTTY_MAGIC;
	}
	HvCall_setLogBufferFormatAndCodepage(HvCall_LogBuffer_ASCII, 437);
	add_preferred_console("viocons", 0, NULL);
	register_console(&viocons_early);
	return 0;
}

console_initcall(viocons_init);
module_init(viocons_init2);