summaryrefslogtreecommitdiff
path: root/drivers/s390/char/con3215.c
blob: 0b05cd76b7d03f26f74d8ad0f2611f05db314a42 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * 3215 line mode terminal driver.
 *
 * Copyright IBM Corp. 1999, 2009
 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 *
 * Updated:
 *  Aug-2000: Added tab support
 *	      Dan Morrison, IBM Corporation <dmorriso@cse.buffalo.edu>
 */

#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/vt_kern.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/panic_notifier.h>
#include <linux/reboot.h>
#include <linux/serial.h> /* ASYNC_* flags */
#include <linux/slab.h>
#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/io.h>
#include <asm/ebcdic.h>
#include <linux/uaccess.h>
#include <asm/delay.h>
#include <asm/cpcmd.h>
#include <asm/setup.h>

#include "ctrlchar.h"

#define NR_3215		    1
#define NR_3215_REQ	    (4*NR_3215)
#define RAW3215_BUFFER_SIZE 65536     /* output buffer size */
#define RAW3215_INBUF_SIZE  256	      /* input buffer size */
#define RAW3215_MIN_SPACE   128	      /* minimum free space for wakeup */
#define RAW3215_MIN_WRITE   1024      /* min. length for immediate output */
#define RAW3215_MAX_BYTES   3968      /* max. bytes to write with one ssch */
#define RAW3215_MAX_NEWLINE 50	      /* max. lines to write with one ssch */
#define RAW3215_NR_CCWS	    3
#define RAW3215_TIMEOUT	    HZ/10     /* time for delayed output */

#define RAW3215_FIXED	    1	      /* 3215 console device is not be freed */
#define RAW3215_WORKING	    4	      /* set if a request is being worked on */
#define RAW3215_THROTTLED   8	      /* set if reading is disabled */
#define RAW3215_STOPPED	    16	      /* set if writing is disabled */
#define RAW3215_TIMER_RUNS  64	      /* set if the output delay timer is on */
#define RAW3215_FLUSHING    128	      /* set to flush buffer (no delay) */

#define TAB_STOP_SIZE	    8	      /* tab stop size */

/*
 * Request types for a 3215 device
 */
enum raw3215_type {
	RAW3215_FREE, RAW3215_READ, RAW3215_WRITE
};

/*
 * Request structure for a 3215 device
 */
struct raw3215_req {
	enum raw3215_type type;	      /* type of the request */
	int start, len;		      /* start index & len in output buffer */
	int delayable;		      /* indication to wait for more data */
	int residual;		      /* residual count for read request */
	struct ccw1 ccws[RAW3215_NR_CCWS]; /* space for the channel program */
	struct raw3215_info *info;    /* pointer to main structure */
	struct raw3215_req *next;     /* pointer to next request */
} __attribute__ ((aligned(8)));

struct raw3215_info {
	struct tty_port port;
	struct ccw_device *cdev;      /* device for tty driver */
	spinlock_t *lock;	      /* pointer to irq lock */
	int flags;		      /* state flags */
	char *buffer;		      /* pointer to output buffer */
	char *inbuf;		      /* pointer to input buffer */
	int head;		      /* first free byte in output buffer */
	int count;		      /* number of bytes in output buffer */
	int written;		      /* number of bytes in write requests */
	struct raw3215_req *queued_read; /* pointer to queued read requests */
	struct raw3215_req *queued_write;/* pointer to queued write requests */
	wait_queue_head_t empty_wait; /* wait queue for flushing */
	struct timer_list timer;      /* timer for delayed output */
	int line_pos;		      /* position on the line (for tabs) */
	char ubuffer[80];	      /* copy_from_user buffer */
};

/* array of 3215 devices structures */
static struct raw3215_info *raw3215[NR_3215];
/* spinlock to protect the raw3215 array */
static DEFINE_SPINLOCK(raw3215_device_lock);
/* list of free request structures */
static struct raw3215_req *raw3215_freelist;
/* spinlock to protect free list */
static DEFINE_SPINLOCK(raw3215_freelist_lock);

static struct tty_driver *tty3215_driver;
static bool con3215_drop = true;

/*
 * Get a request structure from the free list
 */
static inline struct raw3215_req *raw3215_alloc_req(void)
{
	struct raw3215_req *req;
	unsigned long flags;

	spin_lock_irqsave(&raw3215_freelist_lock, flags);
	req = raw3215_freelist;
	raw3215_freelist = req->next;
	spin_unlock_irqrestore(&raw3215_freelist_lock, flags);
	return req;
}

/*
 * Put a request structure back to the free list
 */
static inline void raw3215_free_req(struct raw3215_req *req)
{
	unsigned long flags;

	if (req->type == RAW3215_FREE)
		return;		/* don't free a free request */
	req->type = RAW3215_FREE;
	spin_lock_irqsave(&raw3215_freelist_lock, flags);
	req->next = raw3215_freelist;
	raw3215_freelist = req;
	spin_unlock_irqrestore(&raw3215_freelist_lock, flags);
}

/*
 * Set up a read request that reads up to 160 byte from the 3215 device.
 * If there is a queued read request it is used, but that shouldn't happen
 * because a 3215 terminal won't accept a new read before the old one is
 * completed.
 */
static void raw3215_mk_read_req(struct raw3215_info *raw)
{
	struct raw3215_req *req;
	struct ccw1 *ccw;

	/* there can only be ONE read request at a time */
	req = raw->queued_read;
	if (req == NULL) {
		/* no queued read request, use new req structure */
		req = raw3215_alloc_req();
		req->type = RAW3215_READ;
		req->info = raw;
		raw->queued_read = req;
	}

	ccw = req->ccws;
	ccw->cmd_code = 0x0A; /* read inquiry */
	ccw->flags = 0x20;    /* ignore incorrect length */
	ccw->count = 160;
	ccw->cda = (__u32)__pa(raw->inbuf);
}

/*
 * Set up a write request with the information from the main structure.
 * A ccw chain is created that writes as much as possible from the output
 * buffer to the 3215 device. If a queued write exists it is replaced by
 * the new, probably lengthened request.
 */
static void raw3215_mk_write_req(struct raw3215_info *raw)
{
	struct raw3215_req *req;
	struct ccw1 *ccw;
	int len, count, ix, lines;

	if (raw->count <= raw->written)
		return;
	/* check if there is a queued write request */
	req = raw->queued_write;
	if (req == NULL) {
		/* no queued write request, use new req structure */
		req = raw3215_alloc_req();
		req->type = RAW3215_WRITE;
		req->info = raw;
		raw->queued_write = req;
	} else {
		raw->written -= req->len;
	}

	ccw = req->ccws;
	req->start = (raw->head - raw->count + raw->written) &
		     (RAW3215_BUFFER_SIZE - 1);
	/*
	 * now we have to count newlines. We can at max accept
	 * RAW3215_MAX_NEWLINE newlines in a single ssch due to
	 * a restriction in VM
	 */
	lines = 0;
	ix = req->start;
	while (lines < RAW3215_MAX_NEWLINE && ix != raw->head) {
		if (raw->buffer[ix] == 0x15)
			lines++;
		ix = (ix + 1) & (RAW3215_BUFFER_SIZE - 1);
	}
	len = ((ix - 1 - req->start) & (RAW3215_BUFFER_SIZE - 1)) + 1;
	if (len > RAW3215_MAX_BYTES)
		len = RAW3215_MAX_BYTES;
	req->len = len;
	raw->written += len;

	/* set the indication if we should try to enlarge this request */
	req->delayable = (ix == raw->head) && (len < RAW3215_MIN_WRITE);

	ix = req->start;
	while (len > 0) {
		if (ccw > req->ccws)
			ccw[-1].flags |= 0x40; /* use command chaining */
		ccw->cmd_code = 0x01; /* write, auto carrier return */
		ccw->flags = 0x20;    /* ignore incorrect length ind.  */
		ccw->cda = (__u32)__pa(raw->buffer + ix);
		count = len;
		if (ix + count > RAW3215_BUFFER_SIZE)
			count = RAW3215_BUFFER_SIZE - ix;
		ccw->count = count;
		len -= count;
		ix = (ix + count) & (RAW3215_BUFFER_SIZE - 1);
		ccw++;
	}
	/*
	 * Add a NOP to the channel program. 3215 devices are purely
	 * emulated and its much better to avoid the channel end
	 * interrupt in this case.
	 */
	if (ccw > req->ccws)
		ccw[-1].flags |= 0x40; /* use command chaining */
	ccw->cmd_code = 0x03; /* NOP */
	ccw->flags = 0;
	ccw->cda = 0;
	ccw->count = 1;
}

/*
 * Start a read or a write request
 */
static void raw3215_start_io(struct raw3215_info *raw)
{
	struct raw3215_req *req;
	int res;

	req = raw->queued_read;
	if (req != NULL &&
	    !(raw->flags & (RAW3215_WORKING | RAW3215_THROTTLED))) {
		/* dequeue request */
		raw->queued_read = NULL;
		res = ccw_device_start(raw->cdev, req->ccws,
				       (unsigned long) req, 0, 0);
		if (res != 0) {
			/* do_IO failed, put request back to queue */
			raw->queued_read = req;
		} else {
			raw->flags |= RAW3215_WORKING;
		}
	}
	req = raw->queued_write;
	if (req != NULL &&
	    !(raw->flags & (RAW3215_WORKING | RAW3215_STOPPED))) {
		/* dequeue request */
		raw->queued_write = NULL;
		res = ccw_device_start(raw->cdev, req->ccws,
				       (unsigned long) req, 0, 0);
		if (res != 0) {
			/* do_IO failed, put request back to queue */
			raw->queued_write = req;
		} else {
			raw->flags |= RAW3215_WORKING;
		}
	}
}

/*
 * Function to start a delayed output after RAW3215_TIMEOUT seconds
 */
static void raw3215_timeout(struct timer_list *t)
{
	struct raw3215_info *raw = from_timer(raw, t, timer);
	unsigned long flags;

	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
	raw->flags &= ~RAW3215_TIMER_RUNS;
	raw3215_mk_write_req(raw);
	raw3215_start_io(raw);
	if ((raw->queued_read || raw->queued_write) &&
	    !(raw->flags & RAW3215_WORKING) &&
	    !(raw->flags & RAW3215_TIMER_RUNS)) {
		raw->timer.expires = RAW3215_TIMEOUT + jiffies;
		add_timer(&raw->timer);
		raw->flags |= RAW3215_TIMER_RUNS;
	}
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Function to conditionally start an IO. A read is started immediately,
 * a write is only started immediately if the flush flag is on or the
 * amount of data is bigger than RAW3215_MIN_WRITE. If a write is not
 * done immediately a timer is started with a delay of RAW3215_TIMEOUT.
 */
static inline void raw3215_try_io(struct raw3215_info *raw)
{
	if (!tty_port_initialized(&raw->port))
		return;
	if (raw->queued_read != NULL)
		raw3215_start_io(raw);
	else if (raw->queued_write != NULL) {
		if ((raw->queued_write->delayable == 0) ||
		    (raw->flags & RAW3215_FLUSHING)) {
			/* execute write requests bigger than minimum size */
			raw3215_start_io(raw);
		}
	}
	if ((raw->queued_read || raw->queued_write) &&
	    !(raw->flags & RAW3215_WORKING) &&
	    !(raw->flags & RAW3215_TIMER_RUNS)) {
		raw->timer.expires = RAW3215_TIMEOUT + jiffies;
		add_timer(&raw->timer);
		raw->flags |= RAW3215_TIMER_RUNS;
	}
}

/*
 * Try to start the next IO and wake up processes waiting on the tty.
 */
static void raw3215_next_io(struct raw3215_info *raw, struct tty_struct *tty)
{
	raw3215_mk_write_req(raw);
	raw3215_try_io(raw);
	if (tty && RAW3215_BUFFER_SIZE - raw->count >= RAW3215_MIN_SPACE)
		tty_wakeup(tty);
}

/*
 * Interrupt routine, called from common io layer
 */
static void raw3215_irq(struct ccw_device *cdev, unsigned long intparm,
			struct irb *irb)
{
	struct raw3215_info *raw;
	struct raw3215_req *req;
	struct tty_struct *tty;
	int cstat, dstat;
	int count;

	raw = dev_get_drvdata(&cdev->dev);
	req = (struct raw3215_req *) intparm;
	tty = tty_port_tty_get(&raw->port);
	cstat = irb->scsw.cmd.cstat;
	dstat = irb->scsw.cmd.dstat;
	if (cstat != 0)
		raw3215_next_io(raw, tty);
	if (dstat & 0x01) { /* we got a unit exception */
		dstat &= ~0x01;	 /* we can ignore it */
	}
	switch (dstat) {
	case 0x80:
		if (cstat != 0)
			break;
		/* Attention interrupt, someone hit the enter key */
		raw3215_mk_read_req(raw);
		raw3215_next_io(raw, tty);
		break;
	case 0x08:
	case 0x0C:
		/* Channel end interrupt. */
		if ((raw = req->info) == NULL)
			goto put_tty;	     /* That shouldn't happen ... */
		if (req->type == RAW3215_READ) {
			/* store residual count, then wait for device end */
			req->residual = irb->scsw.cmd.count;
		}
		if (dstat == 0x08)
			break;
		fallthrough;
	case 0x04:
		/* Device end interrupt. */
		if ((raw = req->info) == NULL)
			goto put_tty;	     /* That shouldn't happen ... */
		if (req->type == RAW3215_READ && tty != NULL) {
			unsigned int cchar;

			count = 160 - req->residual;
			EBCASC(raw->inbuf, count);
			cchar = ctrlchar_handle(raw->inbuf, count, tty);
			switch (cchar & CTRLCHAR_MASK) {
			case CTRLCHAR_SYSRQ:
				break;

			case CTRLCHAR_CTRL:
				tty_insert_flip_char(&raw->port, cchar,
						TTY_NORMAL);
				tty_flip_buffer_push(&raw->port);
				break;

			case CTRLCHAR_NONE:
				if (count < 2 ||
				    (strncmp(raw->inbuf+count-2, "\252n", 2) &&
				     strncmp(raw->inbuf+count-2, "^n", 2)) ) {
					/* add the auto \n */
					raw->inbuf[count] = '\n';
					count++;
				} else
					count -= 2;
				tty_insert_flip_string(&raw->port, raw->inbuf,
						count);
				tty_flip_buffer_push(&raw->port);
				break;
			}
		} else if (req->type == RAW3215_WRITE) {
			raw->count -= req->len;
			raw->written -= req->len;
		}
		raw->flags &= ~RAW3215_WORKING;
		raw3215_free_req(req);
		/* check for empty wait */
		if (waitqueue_active(&raw->empty_wait) &&
		    raw->queued_write == NULL &&
		    raw->queued_read == NULL) {
			wake_up_interruptible(&raw->empty_wait);
		}
		raw3215_next_io(raw, tty);
		break;
	default:
		/* Strange interrupt, I'll do my best to clean up */
		if (req != NULL && req->type != RAW3215_FREE) {
			if (req->type == RAW3215_WRITE) {
				raw->count -= req->len;
				raw->written -= req->len;
			}
			raw->flags &= ~RAW3215_WORKING;
			raw3215_free_req(req);
		}
		raw3215_next_io(raw, tty);
	}
put_tty:
	tty_kref_put(tty);
}

/*
 * Need to drop data to avoid blocking. Drop as much data as possible.
 * This is unqueued part in the buffer and the queued part in the request.
 * Also adjust the head position to append new data and set count
 * accordingly.
 *
 * Return number of bytes available in buffer.
 */
static unsigned int raw3215_drop(struct raw3215_info *raw)
{
	struct raw3215_req *req;

	req = raw->queued_write;
	if (req) {
		/* Drop queued data and delete request */
		raw->written -= req->len;
		raw3215_free_req(req);
		raw->queued_write = NULL;
	}
	raw->head = (raw->head - raw->count + raw->written) &
		    (RAW3215_BUFFER_SIZE - 1);
	raw->count = raw->written;

	return RAW3215_BUFFER_SIZE - raw->count;
}

/*
 * Wait until length bytes are available int the output buffer.
 * If drop mode is active and wait condition holds true, start dropping
 * data.
 * Has to be called with the s390irq lock held. Can be called
 * disabled.
 */
static unsigned int raw3215_make_room(struct raw3215_info *raw,
				      unsigned int length, bool drop)
{
	while (RAW3215_BUFFER_SIZE - raw->count < length) {
		if (drop)
			return raw3215_drop(raw);

		/* there might be a request pending */
		raw->flags |= RAW3215_FLUSHING;
		raw3215_mk_write_req(raw);
		raw3215_try_io(raw);
		raw->flags &= ~RAW3215_FLUSHING;
#ifdef CONFIG_TN3215_CONSOLE
		ccw_device_wait_idle(raw->cdev);
#endif
		/* Enough room freed up ? */
		if (RAW3215_BUFFER_SIZE - raw->count >= length)
			break;
		/* there might be another cpu waiting for the lock */
		spin_unlock(get_ccwdev_lock(raw->cdev));
		udelay(100);
		spin_lock(get_ccwdev_lock(raw->cdev));
	}
	return length;
}

#define	RAW3215_COUNT	1
#define	RAW3215_STORE	2

/*
 * Add text to console buffer. Find tabs in input and calculate size
 * including tab replacement.
 * This function operates in 2 different modes, depending on parameter
 * opmode:
 * RAW3215_COUNT: Get the size needed for the input string with
 *	proper tab replacement calculation.
 *	Return value is the number of bytes required to store the
 *	input. However no data is actually stored.
 *	The parameter todrop is not used.
 * RAW3215_STORE: Add data to the console buffer. The parameter todrop is
 *	valid and contains the number of bytes to be dropped from head of
 *	string	without blocking.
 *	Return value is the number of bytes copied.
 */
static unsigned int raw3215_addtext(const char *str, unsigned int length,
				    struct raw3215_info *raw, int opmode,
				    unsigned int todrop)
{
	unsigned int c, ch, i, blanks, expanded_size = 0;
	unsigned int column = raw->line_pos;

	if (opmode == RAW3215_COUNT)
		todrop = 0;

	for (c = 0; c < length; ++c) {
		blanks = 1;
		ch = str[c];

		switch (ch) {
		case '\n':
			expanded_size++;
			column = 0;
			break;
		case '\t':
			blanks = TAB_STOP_SIZE - (column % TAB_STOP_SIZE);
			column += blanks;
			expanded_size += blanks;
			ch = ' ';
			break;
		default:
			expanded_size++;
			column++;
			break;
		}

		if (opmode == RAW3215_COUNT)
			continue;
		if (todrop && expanded_size < todrop)	/* Drop head data */
			continue;
		for (i = 0; i < blanks; i++) {
			raw->buffer[raw->head] = (char)_ascebc[(int)ch];
			raw->head = (raw->head + 1) & (RAW3215_BUFFER_SIZE - 1);
			raw->count++;
		}
		raw->line_pos = column;
	}
	return expanded_size - todrop;
}

/*
 * String write routine for 3215 devices
 */
static void raw3215_write(struct raw3215_info *raw, const char *str,
			  unsigned int length)
{
	unsigned int count, avail;
	unsigned long flags;

	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);

	count = raw3215_addtext(str, length, raw, RAW3215_COUNT, 0);

	avail = raw3215_make_room(raw, count, con3215_drop);
	if (avail) {
		raw3215_addtext(str, length, raw, RAW3215_STORE,
				count - avail);
	}
	if (!(raw->flags & RAW3215_WORKING)) {
		raw3215_mk_write_req(raw);
		/* start or queue request */
		raw3215_try_io(raw);
	}
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Put character routine for 3215 devices
 */
static void raw3215_putchar(struct raw3215_info *raw, unsigned char ch)
{
	raw3215_write(raw, &ch, 1);
}

/*
 * Flush routine, it simply sets the flush flag and tries to start
 * pending IO.
 */
static void raw3215_flush_buffer(struct raw3215_info *raw)
{
	unsigned long flags;

	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
	if (raw->count > 0) {
		raw->flags |= RAW3215_FLUSHING;
		raw3215_try_io(raw);
		raw->flags &= ~RAW3215_FLUSHING;
	}
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

/*
 * Fire up a 3215 device.
 */
static int raw3215_startup(struct raw3215_info *raw)
{
	unsigned long flags;

	if (tty_port_initialized(&raw->port))
		return 0;
	raw->line_pos = 0;
	tty_port_set_initialized(&raw->port, true);
	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
	raw3215_try_io(raw);
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);

	return 0;
}

/*
 * Shutdown a 3215 device.
 */
static void raw3215_shutdown(struct raw3215_info *raw)
{
	DECLARE_WAITQUEUE(wait, current);
	unsigned long flags;

	if (!tty_port_initialized(&raw->port) || (raw->flags & RAW3215_FIXED))
		return;
	/* Wait for outstanding requests, then free irq */
	spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
	if ((raw->flags & RAW3215_WORKING) ||
	    raw->queued_write != NULL ||
	    raw->queued_read != NULL) {
		add_wait_queue(&raw->empty_wait, &wait);
		set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
		schedule();
		spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
		remove_wait_queue(&raw->empty_wait, &wait);
		set_current_state(TASK_RUNNING);
		tty_port_set_initialized(&raw->port, true);
	}
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
}

static struct raw3215_info *raw3215_alloc_info(void)
{
	struct raw3215_info *info;

	info = kzalloc(sizeof(struct raw3215_info), GFP_KERNEL | GFP_DMA);
	if (!info)
		return NULL;

	info->buffer = kzalloc(RAW3215_BUFFER_SIZE, GFP_KERNEL | GFP_DMA);
	info->inbuf = kzalloc(RAW3215_INBUF_SIZE, GFP_KERNEL | GFP_DMA);
	if (!info->buffer || !info->inbuf) {
		kfree(info->inbuf);
		kfree(info->buffer);
		kfree(info);
		return NULL;
	}

	timer_setup(&info->timer, raw3215_timeout, 0);
	init_waitqueue_head(&info->empty_wait);
	tty_port_init(&info->port);

	return info;
}

static void raw3215_free_info(struct raw3215_info *raw)
{
	kfree(raw->inbuf);
	kfree(raw->buffer);
	tty_port_destroy(&raw->port);
	kfree(raw);
}

static int raw3215_probe(struct ccw_device *cdev)
{
	struct raw3215_info *raw;
	int line;

	/* Console is special. */
	if (raw3215[0] && (raw3215[0] == dev_get_drvdata(&cdev->dev)))
		return 0;

	raw = raw3215_alloc_info();
	if (raw == NULL)
		return -ENOMEM;

	raw->cdev = cdev;
	dev_set_drvdata(&cdev->dev, raw);
	cdev->handler = raw3215_irq;

	spin_lock(&raw3215_device_lock);
	for (line = 0; line < NR_3215; line++) {
		if (!raw3215[line]) {
			raw3215[line] = raw;
			break;
		}
	}
	spin_unlock(&raw3215_device_lock);
	if (line == NR_3215) {
		raw3215_free_info(raw);
		return -ENODEV;
	}

	return 0;
}

static void raw3215_remove(struct ccw_device *cdev)
{
	struct raw3215_info *raw;
	unsigned int line;

	ccw_device_set_offline(cdev);
	raw = dev_get_drvdata(&cdev->dev);
	if (raw) {
		spin_lock(&raw3215_device_lock);
		for (line = 0; line < NR_3215; line++)
			if (raw3215[line] == raw)
				break;
		raw3215[line] = NULL;
		spin_unlock(&raw3215_device_lock);
		dev_set_drvdata(&cdev->dev, NULL);
		raw3215_free_info(raw);
	}
}

static int raw3215_set_online(struct ccw_device *cdev)
{
	struct raw3215_info *raw;

	raw = dev_get_drvdata(&cdev->dev);
	if (!raw)
		return -ENODEV;

	return raw3215_startup(raw);
}

static int raw3215_set_offline(struct ccw_device *cdev)
{
	struct raw3215_info *raw;

	raw = dev_get_drvdata(&cdev->dev);
	if (!raw)
		return -ENODEV;

	raw3215_shutdown(raw);

	return 0;
}

static struct ccw_device_id raw3215_id[] = {
	{ CCW_DEVICE(0x3215, 0) },
	{ /* end of list */ },
};

static ssize_t con_drop_store(struct device_driver *dev, const char *buf, size_t count)
{
	bool drop;
	int rc;

	rc = kstrtobool(buf, &drop);
	if (!rc)
		con3215_drop = drop;
	return rc ?: count;
}

static ssize_t con_drop_show(struct device_driver *dev, char *buf)
{
	return sysfs_emit(buf, "%d\n", con3215_drop ? 1 : 0);
}

static DRIVER_ATTR_RW(con_drop);

static struct attribute *con3215_drv_attrs[] = {
	&driver_attr_con_drop.attr,
	NULL,
};

static struct attribute_group con3215_drv_attr_group = {
	.attrs = con3215_drv_attrs,
	NULL,
};

static const struct attribute_group *con3215_drv_attr_groups[] = {
	&con3215_drv_attr_group,
	NULL,
};

static struct ccw_driver raw3215_ccw_driver = {
	.driver = {
		.name	= "3215",
		.groups = con3215_drv_attr_groups,
		.owner	= THIS_MODULE,
	},
	.ids		= raw3215_id,
	.probe		= &raw3215_probe,
	.remove		= &raw3215_remove,
	.set_online	= &raw3215_set_online,
	.set_offline	= &raw3215_set_offline,
	.int_class	= IRQIO_C15,
};

static void handle_write(struct raw3215_info *raw, const char *str, int count)
{
	int i;

	while (count > 0) {
		i = min_t(int, count, RAW3215_BUFFER_SIZE - 1);
		raw3215_write(raw, str, i);
		count -= i;
		str += i;
	}
}

#ifdef CONFIG_TN3215_CONSOLE
/*
 * Write a string to the 3215 console
 */
static void con3215_write(struct console *co, const char *str, unsigned int count)
{
	handle_write(raw3215[0], str, count);
}

static struct tty_driver *con3215_device(struct console *c, int *index)
{
	*index = c->index;
	return tty3215_driver;
}

/*
 * The below function is called as a panic/reboot notifier before the
 * system enters a disabled, endless loop.
 *
 * Notice we must use the spin_trylock() alternative, to prevent lockups
 * in atomic context (panic routine runs with secondary CPUs, local IRQs
 * and preemption disabled).
 */
static int con3215_notify(struct notifier_block *self,
			  unsigned long event, void *data)
{
	struct raw3215_info *raw;
	unsigned long flags;

	raw = raw3215[0];  /* console 3215 is the first one */
	if (!spin_trylock_irqsave(get_ccwdev_lock(raw->cdev), flags))
		return NOTIFY_DONE;
	raw3215_make_room(raw, RAW3215_BUFFER_SIZE, false);
	spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);

	return NOTIFY_DONE;
}

static struct notifier_block on_panic_nb = {
	.notifier_call = con3215_notify,
	.priority = INT_MIN + 1, /* run the callback late */
};

static struct notifier_block on_reboot_nb = {
	.notifier_call = con3215_notify,
	.priority = INT_MIN + 1, /* run the callback late */
};

/*
 *  The console structure for the 3215 console
 */
static struct console con3215 = {
	.name	 = "ttyS",
	.write	 = con3215_write,
	.device	 = con3215_device,
	.flags	 = CON_PRINTBUFFER,
};

/*
 * 3215 console initialization code called from console_init().
 */
static int __init con3215_init(void)
{
	struct ccw_device *cdev;
	struct raw3215_info *raw;
	struct raw3215_req *req;
	int i;

	/* Check if 3215 is to be the console */
	if (!CONSOLE_IS_3215)
		return -ENODEV;

	/* Set the console mode for VM */
	if (MACHINE_IS_VM) {
		cpcmd("TERM CONMODE 3215", NULL, 0, NULL);
		cpcmd("TERM AUTOCR OFF", NULL, 0, NULL);
	}

	/* allocate 3215 request structures */
	raw3215_freelist = NULL;
	for (i = 0; i < NR_3215_REQ; i++) {
		req = kzalloc(sizeof(struct raw3215_req), GFP_KERNEL | GFP_DMA);
		if (!req)
			return -ENOMEM;
		req->next = raw3215_freelist;
		raw3215_freelist = req;
	}

	cdev = ccw_device_create_console(&raw3215_ccw_driver);
	if (IS_ERR(cdev))
		return -ENODEV;

	raw3215[0] = raw = raw3215_alloc_info();
	raw->cdev = cdev;
	dev_set_drvdata(&cdev->dev, raw);
	cdev->handler = raw3215_irq;

	raw->flags |= RAW3215_FIXED;
	if (ccw_device_enable_console(cdev)) {
		ccw_device_destroy_console(cdev);
		raw3215_free_info(raw);
		raw3215[0] = NULL;
		return -ENODEV;
	}

	/* Request the console irq */
	if (raw3215_startup(raw) != 0) {
		raw3215_free_info(raw);
		raw3215[0] = NULL;
		return -ENODEV;
	}
	atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
	register_reboot_notifier(&on_reboot_nb);
	register_console(&con3215);
	return 0;
}
console_initcall(con3215_init);
#endif

static int tty3215_install(struct tty_driver *driver, struct tty_struct *tty)
{
	struct raw3215_info *raw;

	raw = raw3215[tty->index];
	if (raw == NULL)
		return -ENODEV;

	tty->driver_data = raw;

	return tty_port_install(&raw->port, driver, tty);
}

/*
 * tty3215_open
 *
 * This routine is called whenever a 3215 tty is opened.
 */
static int tty3215_open(struct tty_struct *tty, struct file * filp)
{
	struct raw3215_info *raw = tty->driver_data;

	tty_port_tty_set(&raw->port, tty);

	/*
	 * Start up 3215 device
	 */
	return raw3215_startup(raw);
}

/*
 * tty3215_close()
 *
 * This routine is called when the 3215 tty is closed. We wait
 * for the remaining request to be completed. Then we clean up.
 */
static void tty3215_close(struct tty_struct *tty, struct file * filp)
{
	struct raw3215_info *raw = tty->driver_data;

	if (raw == NULL || tty->count > 1)
		return;
	tty->closing = 1;
	/* Shutdown the terminal */
	raw3215_shutdown(raw);
	tty->closing = 0;
	tty_port_tty_set(&raw->port, NULL);
}

/*
 * Returns the amount of free space in the output buffer.
 */
static unsigned int tty3215_write_room(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;

	/* Subtract TAB_STOP_SIZE to allow for a tab, 8 <<< 64K */
	if ((RAW3215_BUFFER_SIZE - raw->count - TAB_STOP_SIZE) >= 0)
		return RAW3215_BUFFER_SIZE - raw->count - TAB_STOP_SIZE;
	else
		return 0;
}

/*
 * String write routine for 3215 ttys
 */
static int tty3215_write(struct tty_struct *tty,
			 const unsigned char *buf, int count)
{
	handle_write(tty->driver_data, buf, count);
	return count;
}

/*
 * Put character routine for 3215 ttys
 */
static int tty3215_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct raw3215_info *raw = tty->driver_data;

	raw3215_putchar(raw, ch);

	return 1;
}

static void tty3215_flush_chars(struct tty_struct *tty)
{
}

/*
 * Returns the number of characters in the output buffer
 */
static unsigned int tty3215_chars_in_buffer(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;

	return raw->count;
}

static void tty3215_flush_buffer(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;

	raw3215_flush_buffer(raw);
	tty_wakeup(tty);
}

/*
 * Disable reading from a 3215 tty
 */
static void tty3215_throttle(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;

	raw->flags |= RAW3215_THROTTLED;
}

/*
 * Enable reading from a 3215 tty
 */
static void tty3215_unthrottle(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;
	unsigned long flags;

	if (raw->flags & RAW3215_THROTTLED) {
		spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
		raw->flags &= ~RAW3215_THROTTLED;
		raw3215_try_io(raw);
		spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
	}
}

/*
 * Disable writing to a 3215 tty
 */
static void tty3215_stop(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;

	raw->flags |= RAW3215_STOPPED;
}

/*
 * Enable writing to a 3215 tty
 */
static void tty3215_start(struct tty_struct *tty)
{
	struct raw3215_info *raw = tty->driver_data;
	unsigned long flags;

	if (raw->flags & RAW3215_STOPPED) {
		spin_lock_irqsave(get_ccwdev_lock(raw->cdev), flags);
		raw->flags &= ~RAW3215_STOPPED;
		raw3215_try_io(raw);
		spin_unlock_irqrestore(get_ccwdev_lock(raw->cdev), flags);
	}
}

static const struct tty_operations tty3215_ops = {
	.install = tty3215_install,
	.open = tty3215_open,
	.close = tty3215_close,
	.write = tty3215_write,
	.put_char = tty3215_put_char,
	.flush_chars = tty3215_flush_chars,
	.write_room = tty3215_write_room,
	.chars_in_buffer = tty3215_chars_in_buffer,
	.flush_buffer = tty3215_flush_buffer,
	.throttle = tty3215_throttle,
	.unthrottle = tty3215_unthrottle,
	.stop = tty3215_stop,
	.start = tty3215_start,
};

static int __init con3215_setup_drop(char *str)
{
	bool drop;
	int rc;

	rc = kstrtobool(str, &drop);
	if (!rc)
		con3215_drop = drop;
	return rc;
}
early_param("con3215_drop", con3215_setup_drop);

/*
 * 3215 tty registration code called from tty_init().
 * Most kernel services (incl. kmalloc) are available at this poimt.
 */
static int __init tty3215_init(void)
{
	struct tty_driver *driver;
	int ret;

	if (!CONSOLE_IS_3215)
		return 0;

	driver = tty_alloc_driver(NR_3215, TTY_DRIVER_REAL_RAW);
	if (IS_ERR(driver))
		return PTR_ERR(driver);

	ret = ccw_driver_register(&raw3215_ccw_driver);
	if (ret) {
		tty_driver_kref_put(driver);
		return ret;
	}
	/*
	 * Initialize the tty_driver structure
	 * Entries in tty3215_driver that are NOT initialized:
	 * proc_entry, set_termios, flush_buffer, set_ldisc, write_proc
	 */

	driver->driver_name = "tty3215";
	driver->name = "ttyS";
	driver->major = TTY_MAJOR;
	driver->minor_start = 64;
	driver->type = TTY_DRIVER_TYPE_SYSTEM;
	driver->subtype = SYSTEM_TYPE_TTY;
	driver->init_termios = tty_std_termios;
	driver->init_termios.c_iflag = IGNBRK | IGNPAR;
	driver->init_termios.c_oflag = ONLCR;
	driver->init_termios.c_lflag = ISIG;
	tty_set_operations(driver, &tty3215_ops);
	ret = tty_register_driver(driver);
	if (ret) {
		tty_driver_kref_put(driver);
		return ret;
	}
	tty3215_driver = driver;
	return 0;
}
device_initcall(tty3215_init);