summaryrefslogtreecommitdiff
path: root/drivers/s390/char/tty3270.c
blob: 48767e6bab9d4654c09223398cb8c08508c65535 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
/*
 *    IBM/3270 Driver - tty functions.
 *
 *  Author(s):
 *    Original 3270 Code for 2.4 written by Richard Hitt (UTS Global)
 *    Rewritten for 2.5 by Martin Schwidefsky <schwidefsky@de.ibm.com>
 *	-- Copyright IBM Corp. 2003
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/tty.h>
#include <linux/vt_kern.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/interrupt.h>

#include <linux/slab.h>
#include <linux/bootmem.h>
#include <linux/compat.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/ebcdic.h>
#include <asm/uaccess.h>

#include "raw3270.h"
#include "tty3270.h"
#include "keyboard.h"

#define TTY3270_CHAR_BUF_SIZE 256
#define TTY3270_OUTPUT_BUFFER_SIZE 1024
#define TTY3270_STRING_PAGES 5

struct tty_driver *tty3270_driver;
static int tty3270_max_index;

static struct raw3270_fn tty3270_fn;

struct tty3270_cell {
	unsigned char character;
	unsigned char highlight;
	unsigned char f_color;
};

struct tty3270_line {
	struct tty3270_cell *cells;
	int len;
};

#define ESCAPE_NPAR 8

/*
 * The main tty view data structure.
 * FIXME:
 * 1) describe line orientation & lines list concept against screen
 * 2) describe conversion of screen to lines
 * 3) describe line format.
 */
struct tty3270 {
	struct raw3270_view view;
	struct tty_port port;
	void **freemem_pages;		/* Array of pages used for freemem. */
	struct list_head freemem;	/* List of free memory for strings. */

	/* Output stuff. */
	struct list_head lines;		/* List of lines. */
	struct list_head update;	/* List of lines to update. */
	unsigned char wcc;		/* Write control character. */
	int nr_lines;			/* # lines in list. */
	int nr_up;			/* # lines up in history. */
	unsigned long update_flags;	/* Update indication bits. */
	struct string *status;		/* Lower right of display. */
	struct raw3270_request *write;	/* Single write request. */
	struct timer_list timer;	/* Output delay timer. */

	/* Current tty screen. */
	unsigned int cx, cy;		/* Current output position. */
	unsigned int highlight;		/* Blink/reverse/underscore */
	unsigned int f_color;		/* Foreground color */
	struct tty3270_line *screen;

	/* Input stuff. */
	struct string *prompt;		/* Output string for input area. */
	struct string *input;		/* Input string for read request. */
	struct raw3270_request *read;	/* Single read request. */
	struct raw3270_request *kreset;	/* Single keyboard reset request. */
	unsigned char inattr;		/* Visible/invisible input. */
	int throttle, attn;		/* tty throttle/unthrottle. */
	struct tasklet_struct readlet;	/* Tasklet to issue read request. */
	struct kbd_data *kbd;		/* key_maps stuff. */

	/* Escape sequence parsing. */
	int esc_state, esc_ques, esc_npar;
	int esc_par[ESCAPE_NPAR];
	unsigned int saved_cx, saved_cy;
	unsigned int saved_highlight, saved_f_color;

	/* Command recalling. */
	struct list_head rcl_lines;	/* List of recallable lines. */
	struct list_head *rcl_walk;	/* Point in rcl_lines list. */
	int rcl_nr, rcl_max;		/* Number/max number of rcl_lines. */

	/* Character array for put_char/flush_chars. */
	unsigned int char_count;
	char char_buf[TTY3270_CHAR_BUF_SIZE];
};

/* tty3270->update_flags. See tty3270_update for details. */
#define TTY_UPDATE_ERASE	1	/* Use EWRITEA instead of WRITE. */
#define TTY_UPDATE_LIST		2	/* Update lines in tty3270->update. */
#define TTY_UPDATE_INPUT	4	/* Update input line. */
#define TTY_UPDATE_STATUS	8	/* Update status line. */
#define TTY_UPDATE_ALL		16	/* Recreate screen. */

static void tty3270_update(struct tty3270 *);

/*
 * Setup timeout for a device. On timeout trigger an update.
 */
static void tty3270_set_timer(struct tty3270 *tp, int expires)
{
	if (expires == 0)
		del_timer(&tp->timer);
	else
		mod_timer(&tp->timer, jiffies + expires);
}

/*
 * The input line are the two last lines of the screen.
 */
static void
tty3270_update_prompt(struct tty3270 *tp, char *input, int count)
{
	struct string *line;
	unsigned int off;

	line = tp->prompt;
	if (count != 0)
		line->string[5] = TF_INMDT;
	else
		line->string[5] = tp->inattr;
	if (count > tp->view.cols * 2 - 11)
		count = tp->view.cols * 2 - 11;
	memcpy(line->string + 6, input, count);
	line->string[6 + count] = TO_IC;
	/* Clear to end of input line. */
	if (count < tp->view.cols * 2 - 11) {
		line->string[7 + count] = TO_RA;
		line->string[10 + count] = 0;
		off = tp->view.cols * tp->view.rows - 9;
		raw3270_buffer_address(tp->view.dev, line->string+count+8, off);
		line->len = 11 + count;
	} else
		line->len = 7 + count;
	tp->update_flags |= TTY_UPDATE_INPUT;
}

static void
tty3270_create_prompt(struct tty3270 *tp)
{
	static const unsigned char blueprint[] =
		{ TO_SBA, 0, 0, 0x6e, TO_SF, TF_INPUT,
		  /* empty input string */
		  TO_IC, TO_RA, 0, 0, 0 };
	struct string *line;
	unsigned int offset;

	line = alloc_string(&tp->freemem,
			    sizeof(blueprint) + tp->view.cols * 2 - 9);
	tp->prompt = line;
	tp->inattr = TF_INPUT;
	/* Copy blueprint to status line */
	memcpy(line->string, blueprint, sizeof(blueprint));
	line->len = sizeof(blueprint);
	/* Set output offsets. */
	offset = tp->view.cols * (tp->view.rows - 2);
	raw3270_buffer_address(tp->view.dev, line->string + 1, offset);
	offset = tp->view.cols * tp->view.rows - 9;
	raw3270_buffer_address(tp->view.dev, line->string + 8, offset);

	/* Allocate input string for reading. */
	tp->input = alloc_string(&tp->freemem, tp->view.cols * 2 - 9 + 6);
}

/*
 * The status line is the last line of the screen. It shows the string
 * "Running"/"Holding" in the lower right corner of the screen.
 */
static void
tty3270_update_status(struct tty3270 * tp)
{
	char *str;

	str = (tp->nr_up != 0) ? "History" : "Running";
	memcpy(tp->status->string + 8, str, 7);
	codepage_convert(tp->view.ascebc, tp->status->string + 8, 7);
	tp->update_flags |= TTY_UPDATE_STATUS;
}

static void
tty3270_create_status(struct tty3270 * tp)
{
	static const unsigned char blueprint[] =
		{ TO_SBA, 0, 0, TO_SF, TF_LOG, TO_SA, TAT_COLOR, TAC_GREEN,
		  0, 0, 0, 0, 0, 0, 0, TO_SF, TF_LOG, TO_SA, TAT_COLOR,
		  TAC_RESET };
	struct string *line;
	unsigned int offset;

	line = alloc_string(&tp->freemem,sizeof(blueprint));
	tp->status = line;
	/* Copy blueprint to status line */
	memcpy(line->string, blueprint, sizeof(blueprint));
	/* Set address to start of status string (= last 9 characters). */
	offset = tp->view.cols * tp->view.rows - 9;
	raw3270_buffer_address(tp->view.dev, line->string + 1, offset);
}

/*
 * Set output offsets to 3270 datastream fragment of a tty string.
 * (TO_SBA offset at the start and TO_RA offset at the end of the string)
 */
static void
tty3270_update_string(struct tty3270 *tp, struct string *line, int nr)
{
	unsigned char *cp;

	raw3270_buffer_address(tp->view.dev, line->string + 1,
			       tp->view.cols * nr);
	cp = line->string + line->len - 4;
	if (*cp == TO_RA)
		raw3270_buffer_address(tp->view.dev, cp + 1,
				       tp->view.cols * (nr + 1));
}

/*
 * Rebuild update list to print all lines.
 */
static void
tty3270_rebuild_update(struct tty3270 *tp)
{
	struct string *s, *n;
	int line, nr_up;

	/* 
	 * Throw away update list and create a new one,
	 * containing all lines that will fit on the screen.
	 */
	list_for_each_entry_safe(s, n, &tp->update, update)
		list_del_init(&s->update);
	line = tp->view.rows - 3;
	nr_up = tp->nr_up;
	list_for_each_entry_reverse(s, &tp->lines, list) {
		if (nr_up > 0) {
			nr_up--;
			continue;
		}
		tty3270_update_string(tp, s, line);
		list_add(&s->update, &tp->update);
		if (--line < 0)
			break;
	}
	tp->update_flags |= TTY_UPDATE_LIST;
}

/*
 * Alloc string for size bytes. If there is not enough room in
 * freemem, free strings until there is room.
 */
static struct string *
tty3270_alloc_string(struct tty3270 *tp, size_t size)
{
	struct string *s, *n;

	s = alloc_string(&tp->freemem, size);
	if (s)
		return s;
	list_for_each_entry_safe(s, n, &tp->lines, list) {
		BUG_ON(tp->nr_lines <= tp->view.rows - 2);
		list_del(&s->list);
		if (!list_empty(&s->update))
			list_del(&s->update);
		tp->nr_lines--;
		if (free_string(&tp->freemem, s) >= size)
			break;
	}
	s = alloc_string(&tp->freemem, size);
	BUG_ON(!s);
	if (tp->nr_up != 0 &&
	    tp->nr_up + tp->view.rows - 2 >= tp->nr_lines) {
		tp->nr_up = tp->nr_lines - tp->view.rows + 2;
		tty3270_rebuild_update(tp);
		tty3270_update_status(tp);
	}
	return s;
}

/*
 * Add an empty line to the list.
 */
static void
tty3270_blank_line(struct tty3270 *tp)
{
	static const unsigned char blueprint[] =
		{ TO_SBA, 0, 0, TO_SA, TAT_EXTHI, TAX_RESET,
		  TO_SA, TAT_COLOR, TAC_RESET, TO_RA, 0, 0, 0 };
	struct string *s;

	s = tty3270_alloc_string(tp, sizeof(blueprint));
	memcpy(s->string, blueprint, sizeof(blueprint));
	s->len = sizeof(blueprint);
	list_add_tail(&s->list, &tp->lines);
	tp->nr_lines++;
	if (tp->nr_up != 0)
		tp->nr_up++;
}

/*
 * Write request completion callback.
 */
static void
tty3270_write_callback(struct raw3270_request *rq, void *data)
{
	struct tty3270 *tp = container_of(rq->view, struct tty3270, view);

	if (rq->rc != 0) {
		/* Write wasn't successful. Refresh all. */
		tp->update_flags = TTY_UPDATE_ALL;
		tty3270_set_timer(tp, 1);
	}
	raw3270_request_reset(rq);
	xchg(&tp->write, rq);
}

/*
 * Update 3270 display.
 */
static void
tty3270_update(struct tty3270 *tp)
{
	static char invalid_sba[2] = { 0xff, 0xff };
	struct raw3270_request *wrq;
	unsigned long updated;
	struct string *s, *n;
	char *sba, *str;
	int rc, len;

	wrq = xchg(&tp->write, 0);
	if (!wrq) {
		tty3270_set_timer(tp, 1);
		return;
	}

	spin_lock(&tp->view.lock);
	updated = 0;
	if (tp->update_flags & TTY_UPDATE_ALL) {
		tty3270_rebuild_update(tp);
		tty3270_update_status(tp);
		tp->update_flags = TTY_UPDATE_ERASE | TTY_UPDATE_LIST |
			TTY_UPDATE_INPUT | TTY_UPDATE_STATUS;
	}
	if (tp->update_flags & TTY_UPDATE_ERASE) {
		/* Use erase write alternate to erase display. */
		raw3270_request_set_cmd(wrq, TC_EWRITEA);
		updated |= TTY_UPDATE_ERASE;
	} else
		raw3270_request_set_cmd(wrq, TC_WRITE);

	raw3270_request_add_data(wrq, &tp->wcc, 1);
	tp->wcc = TW_NONE;

	/*
	 * Update status line.
	 */
	if (tp->update_flags & TTY_UPDATE_STATUS)
		if (raw3270_request_add_data(wrq, tp->status->string,
					     tp->status->len) == 0)
			updated |= TTY_UPDATE_STATUS;

	/*
	 * Write input line.
	 */
	if (tp->update_flags & TTY_UPDATE_INPUT)
		if (raw3270_request_add_data(wrq, tp->prompt->string,
					     tp->prompt->len) == 0)
			updated |= TTY_UPDATE_INPUT;

	sba = invalid_sba;
	
	if (tp->update_flags & TTY_UPDATE_LIST) {
		/* Write strings in the update list to the screen. */
		list_for_each_entry_safe(s, n, &tp->update, update) {
			str = s->string;
			len = s->len;
			/*
			 * Skip TO_SBA at the start of the string if the
			 * last output position matches the start address
			 * of this line.
			 */
			if (s->string[1] == sba[0] && s->string[2] == sba[1])
				str += 3, len -= 3;
			if (raw3270_request_add_data(wrq, str, len) != 0)
				break;
			list_del_init(&s->update);
			sba = s->string + s->len - 3;
		}
		if (list_empty(&tp->update))
			updated |= TTY_UPDATE_LIST;
	}
	wrq->callback = tty3270_write_callback;
	rc = raw3270_start(&tp->view, wrq);
	if (rc == 0) {
		tp->update_flags &= ~updated;
		if (tp->update_flags)
			tty3270_set_timer(tp, 1);
	} else {
		raw3270_request_reset(wrq);
		xchg(&tp->write, wrq);
	}
	spin_unlock(&tp->view.lock);
}

/*
 * Command recalling.
 */
static void
tty3270_rcl_add(struct tty3270 *tp, char *input, int len)
{
	struct string *s;

	tp->rcl_walk = NULL;
	if (len <= 0)
		return;
	if (tp->rcl_nr >= tp->rcl_max) {
		s = list_entry(tp->rcl_lines.next, struct string, list);
		list_del(&s->list);
		free_string(&tp->freemem, s);
		tp->rcl_nr--;
	}
	s = tty3270_alloc_string(tp, len);
	memcpy(s->string, input, len);
	list_add_tail(&s->list, &tp->rcl_lines);
	tp->rcl_nr++;
}

static void
tty3270_rcl_backward(struct kbd_data *kbd)
{
	struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);
	struct string *s;

	spin_lock_bh(&tp->view.lock);
	if (tp->inattr == TF_INPUT) {
		if (tp->rcl_walk && tp->rcl_walk->prev != &tp->rcl_lines)
			tp->rcl_walk = tp->rcl_walk->prev;
		else if (!list_empty(&tp->rcl_lines))
			tp->rcl_walk = tp->rcl_lines.prev;
		s = tp->rcl_walk ? 
			list_entry(tp->rcl_walk, struct string, list) : NULL;
		if (tp->rcl_walk) {
			s = list_entry(tp->rcl_walk, struct string, list);
			tty3270_update_prompt(tp, s->string, s->len);
		} else
			tty3270_update_prompt(tp, NULL, 0);
		tty3270_set_timer(tp, 1);
	}
	spin_unlock_bh(&tp->view.lock);
}

/*
 * Deactivate tty view.
 */
static void
tty3270_exit_tty(struct kbd_data *kbd)
{
	struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);

	raw3270_deactivate_view(&tp->view);
}

/*
 * Scroll forward in history.
 */
static void
tty3270_scroll_forward(struct kbd_data *kbd)
{
	struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);
	int nr_up;

	spin_lock_bh(&tp->view.lock);
	nr_up = tp->nr_up - tp->view.rows + 2;
	if (nr_up < 0)
		nr_up = 0;
	if (nr_up != tp->nr_up) {
		tp->nr_up = nr_up;
		tty3270_rebuild_update(tp);
		tty3270_update_status(tp);
		tty3270_set_timer(tp, 1);
	}
	spin_unlock_bh(&tp->view.lock);
}

/*
 * Scroll backward in history.
 */
static void
tty3270_scroll_backward(struct kbd_data *kbd)
{
	struct tty3270 *tp = container_of(kbd->port, struct tty3270, port);
	int nr_up;

	spin_lock_bh(&tp->view.lock);
	nr_up = tp->nr_up + tp->view.rows - 2;
	if (nr_up + tp->view.rows - 2 > tp->nr_lines)
		nr_up = tp->nr_lines - tp->view.rows + 2;
	if (nr_up != tp->nr_up) {
		tp->nr_up = nr_up;
		tty3270_rebuild_update(tp);
		tty3270_update_status(tp);
		tty3270_set_timer(tp, 1);
	}
	spin_unlock_bh(&tp->view.lock);
}

/*
 * Pass input line to tty.
 */
static void
tty3270_read_tasklet(struct raw3270_request *rrq)
{
	static char kreset_data = TW_KR;
	struct tty3270 *tp = container_of(rrq->view, struct tty3270, view);
	char *input;
	int len;

	spin_lock_bh(&tp->view.lock);
	/*
	 * Two AID keys are special: For 0x7d (enter) the input line
	 * has to be emitted to the tty and for 0x6d the screen
	 * needs to be redrawn.
	 */
	input = NULL;
	len = 0;
	if (tp->input->string[0] == 0x7d) {
		/* Enter: write input to tty. */
		input = tp->input->string + 6;
		len = tp->input->len - 6 - rrq->rescnt;
		if (tp->inattr != TF_INPUTN)
			tty3270_rcl_add(tp, input, len);
		if (tp->nr_up > 0) {
			tp->nr_up = 0;
			tty3270_rebuild_update(tp);
			tty3270_update_status(tp);
		}
		/* Clear input area. */
		tty3270_update_prompt(tp, NULL, 0);
		tty3270_set_timer(tp, 1);
	} else if (tp->input->string[0] == 0x6d) {
		/* Display has been cleared. Redraw. */
		tp->update_flags = TTY_UPDATE_ALL;
		tty3270_set_timer(tp, 1);
	}
	spin_unlock_bh(&tp->view.lock);

	/* Start keyboard reset command. */
	raw3270_request_reset(tp->kreset);
	raw3270_request_set_cmd(tp->kreset, TC_WRITE);
	raw3270_request_add_data(tp->kreset, &kreset_data, 1);
	raw3270_start(&tp->view, tp->kreset);

	while (len-- > 0)
		kbd_keycode(tp->kbd, *input++);
	/* Emit keycode for AID byte. */
	kbd_keycode(tp->kbd, 256 + tp->input->string[0]);

	raw3270_request_reset(rrq);
	xchg(&tp->read, rrq);
	raw3270_put_view(&tp->view);
}

/*
 * Read request completion callback.
 */
static void
tty3270_read_callback(struct raw3270_request *rq, void *data)
{
	struct tty3270 *tp = container_of(rq->view, struct tty3270, view);
	raw3270_get_view(rq->view);
	/* Schedule tasklet to pass input to tty. */
	tasklet_schedule(&tp->readlet);
}

/*
 * Issue a read request. Call with device lock.
 */
static void
tty3270_issue_read(struct tty3270 *tp, int lock)
{
	struct raw3270_request *rrq;
	int rc;

	rrq = xchg(&tp->read, 0);
	if (!rrq)
		/* Read already scheduled. */
		return;
	rrq->callback = tty3270_read_callback;
	rrq->callback_data = tp;
	raw3270_request_set_cmd(rrq, TC_READMOD);
	raw3270_request_set_data(rrq, tp->input->string, tp->input->len);
	/* Issue the read modified request. */
	if (lock) {
		rc = raw3270_start(&tp->view, rrq);
	} else
		rc = raw3270_start_irq(&tp->view, rrq);
	if (rc) {
		raw3270_request_reset(rrq);
		xchg(&tp->read, rrq);
	}
}

/*
 * Switch to the tty view.
 */
static int
tty3270_activate(struct raw3270_view *view)
{
	struct tty3270 *tp = container_of(view, struct tty3270, view);

	tp->update_flags = TTY_UPDATE_ALL;
	tty3270_set_timer(tp, 1);
	return 0;
}

static void
tty3270_deactivate(struct raw3270_view *view)
{
	struct tty3270 *tp = container_of(view, struct tty3270, view);

	del_timer(&tp->timer);
}

static int
tty3270_irq(struct tty3270 *tp, struct raw3270_request *rq, struct irb *irb)
{
	/* Handle ATTN. Schedule tasklet to read aid. */
	if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION) {
		if (!tp->throttle)
			tty3270_issue_read(tp, 0);
		else
			tp->attn = 1;
	}

	if (rq) {
		if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK)
			rq->rc = -EIO;
		else
			/* Normal end. Copy residual count. */
			rq->rescnt = irb->scsw.cmd.count;
	}
	return RAW3270_IO_DONE;
}

/*
 * Allocate tty3270 structure.
 */
static struct tty3270 *
tty3270_alloc_view(void)
{
	struct tty3270 *tp;
	int pages;

	tp = kzalloc(sizeof(struct tty3270), GFP_KERNEL);
	if (!tp)
		goto out_err;
	tp->freemem_pages =
		kmalloc(sizeof(void *) * TTY3270_STRING_PAGES, GFP_KERNEL);
	if (!tp->freemem_pages)
		goto out_tp;
	INIT_LIST_HEAD(&tp->freemem);
	INIT_LIST_HEAD(&tp->lines);
	INIT_LIST_HEAD(&tp->update);
	INIT_LIST_HEAD(&tp->rcl_lines);
	tp->rcl_max = 20;

	for (pages = 0; pages < TTY3270_STRING_PAGES; pages++) {
		tp->freemem_pages[pages] = (void *)
			__get_free_pages(GFP_KERNEL|GFP_DMA, 0);
		if (!tp->freemem_pages[pages])
			goto out_pages;
		add_string_memory(&tp->freemem,
				  tp->freemem_pages[pages], PAGE_SIZE);
	}
	tp->write = raw3270_request_alloc(TTY3270_OUTPUT_BUFFER_SIZE);
	if (IS_ERR(tp->write))
		goto out_pages;
	tp->read = raw3270_request_alloc(0);
	if (IS_ERR(tp->read))
		goto out_write;
	tp->kreset = raw3270_request_alloc(1);
	if (IS_ERR(tp->kreset))
		goto out_read;
	tp->kbd = kbd_alloc();
	if (!tp->kbd)
		goto out_reset;

	tty_port_init(&tp->port);
	setup_timer(&tp->timer, (void (*)(unsigned long)) tty3270_update,
		    (unsigned long) tp);
	tasklet_init(&tp->readlet,
		     (void (*)(unsigned long)) tty3270_read_tasklet,
		     (unsigned long) tp->read);

	return tp;

out_reset:
	raw3270_request_free(tp->kreset);
out_read:
	raw3270_request_free(tp->read);
out_write:
	raw3270_request_free(tp->write);
out_pages:
	while (pages--)
		free_pages((unsigned long) tp->freemem_pages[pages], 0);
	kfree(tp->freemem_pages);
	tty_port_destroy(&tp->port);
out_tp:
	kfree(tp);
out_err:
	return ERR_PTR(-ENOMEM);
}

/*
 * Free tty3270 structure.
 */
static void
tty3270_free_view(struct tty3270 *tp)
{
	int pages;

	del_timer_sync(&tp->timer);
	kbd_free(tp->kbd);
	raw3270_request_free(tp->kreset);
	raw3270_request_free(tp->read);
	raw3270_request_free(tp->write);
	for (pages = 0; pages < TTY3270_STRING_PAGES; pages++)
		free_pages((unsigned long) tp->freemem_pages[pages], 0);
	kfree(tp->freemem_pages);
	tty_port_destroy(&tp->port);
	kfree(tp);
}

/*
 * Allocate tty3270 screen.
 */
static int
tty3270_alloc_screen(struct tty3270 *tp)
{
	unsigned long size;
	int lines;

	size = sizeof(struct tty3270_line) * (tp->view.rows - 2);
	tp->screen = kzalloc(size, GFP_KERNEL);
	if (!tp->screen)
		goto out_err;
	for (lines = 0; lines < tp->view.rows - 2; lines++) {
		size = sizeof(struct tty3270_cell) * tp->view.cols;
		tp->screen[lines].cells = kzalloc(size, GFP_KERNEL);
		if (!tp->screen[lines].cells)
			goto out_screen;
	}
	return 0;
out_screen:
	while (lines--)
		kfree(tp->screen[lines].cells);
	kfree(tp->screen);
out_err:
	return -ENOMEM;
}

/*
 * Free tty3270 screen.
 */
static void
tty3270_free_screen(struct tty3270 *tp)
{
	int lines;

	for (lines = 0; lines < tp->view.rows - 2; lines++)
		kfree(tp->screen[lines].cells);
	kfree(tp->screen);
}

/*
 * Unlink tty3270 data structure from tty.
 */
static void
tty3270_release(struct raw3270_view *view)
{
	struct tty3270 *tp = container_of(view, struct tty3270, view);
	struct tty_struct *tty = tty_port_tty_get(&tp->port);

	if (tty) {
		tty->driver_data = NULL;
		tty_port_tty_set(&tp->port, NULL);
		tty_hangup(tty);
		raw3270_put_view(&tp->view);
		tty_kref_put(tty);
	}
}

/*
 * Free tty3270 data structure
 */
static void
tty3270_free(struct raw3270_view *view)
{
	struct tty3270 *tp = container_of(view, struct tty3270, view);
	tty3270_free_screen(tp);
	tty3270_free_view(tp);
}

/*
 * Delayed freeing of tty3270 views.
 */
static void
tty3270_del_views(void)
{
	int i;

	for (i = RAW3270_FIRSTMINOR; i <= tty3270_max_index; i++) {
		struct raw3270_view *view = raw3270_find_view(&tty3270_fn, i);
		if (!IS_ERR(view))
			raw3270_del_view(view);
	}
}

static struct raw3270_fn tty3270_fn = {
	.activate = tty3270_activate,
	.deactivate = tty3270_deactivate,
	.intv = (void *) tty3270_irq,
	.release = tty3270_release,
	.free = tty3270_free
};

/*
 * This routine is called whenever a 3270 tty is opened first time.
 */
static int tty3270_install(struct tty_driver *driver, struct tty_struct *tty)
{
	struct raw3270_view *view;
	struct tty3270 *tp;
	int i, rc;

	/* Check if the tty3270 is already there. */
	view = raw3270_find_view(&tty3270_fn, tty->index);
	if (!IS_ERR(view)) {
		tp = container_of(view, struct tty3270, view);
		tty->driver_data = tp;
		tty->winsize.ws_row = tp->view.rows - 2;
		tty->winsize.ws_col = tp->view.cols;
		tty->low_latency = 0;
		/* why to reassign? */
		tty_port_tty_set(&tp->port, tty);
		tp->inattr = TF_INPUT;
		return tty_port_install(&tp->port, driver, tty);
	}
	if (tty3270_max_index < tty->index)
		tty3270_max_index = tty->index;

	/* Quick exit if there is no device for tty->index. */
	if (PTR_ERR(view) == -ENODEV)
		return -ENODEV;

	/* Allocate tty3270 structure on first open. */
	tp = tty3270_alloc_view();
	if (IS_ERR(tp))
		return PTR_ERR(tp);

	rc = raw3270_add_view(&tp->view, &tty3270_fn, tty->index);
	if (rc) {
		tty3270_free_view(tp);
		return rc;
	}

	rc = tty3270_alloc_screen(tp);
	if (rc) {
		raw3270_put_view(&tp->view);
		raw3270_del_view(&tp->view);
		return rc;
	}

	tty_port_tty_set(&tp->port, tty);
	tty->low_latency = 0;
	tty->winsize.ws_row = tp->view.rows - 2;
	tty->winsize.ws_col = tp->view.cols;

	tty3270_create_prompt(tp);
	tty3270_create_status(tp);
	tty3270_update_status(tp);

	/* Create blank line for every line in the tty output area. */
	for (i = 0; i < tp->view.rows - 2; i++)
		tty3270_blank_line(tp);

	tp->kbd->port = &tp->port;
	tp->kbd->fn_handler[KVAL(K_INCRCONSOLE)] = tty3270_exit_tty;
	tp->kbd->fn_handler[KVAL(K_SCROLLBACK)] = tty3270_scroll_backward;
	tp->kbd->fn_handler[KVAL(K_SCROLLFORW)] = tty3270_scroll_forward;
	tp->kbd->fn_handler[KVAL(K_CONS)] = tty3270_rcl_backward;
	kbd_ascebc(tp->kbd, tp->view.ascebc);

	raw3270_activate_view(&tp->view);

	rc = tty_port_install(&tp->port, driver, tty);
	if (rc) {
		raw3270_put_view(&tp->view);
		return rc;
	}

	tty->driver_data = tp;

	return 0;
}

/*
 * This routine is called whenever a 3270 tty is opened.
 */
static int
tty3270_open(struct tty_struct *tty, struct file *filp)
{
	struct tty3270 *tp = tty->driver_data;
	struct tty_port *port = &tp->port;

	port->count++;
	tty_port_tty_set(port, tty);
	return 0;
}

/*
 * This routine is called when the 3270 tty is closed. We wait
 * for the remaining request to be completed. Then we clean up.
 */
static void
tty3270_close(struct tty_struct *tty, struct file * filp)
{
	struct tty3270 *tp = tty->driver_data;

	if (tty->count > 1)
		return;
	if (tp) {
		tty->driver_data = NULL;
		tty_port_tty_set(&tp->port, NULL);
	}
}

static void tty3270_cleanup(struct tty_struct *tty)
{
	struct tty3270 *tp = tty->driver_data;

	if (tp)
		raw3270_put_view(&tp->view);
}

/*
 * We always have room.
 */
static int
tty3270_write_room(struct tty_struct *tty)
{
	return INT_MAX;
}

/*
 * Insert character into the screen at the current position with the
 * current color and highlight. This function does NOT do cursor movement.
 */
static void tty3270_put_character(struct tty3270 *tp, char ch)
{
	struct tty3270_line *line;
	struct tty3270_cell *cell;

	line = tp->screen + tp->cy;
	if (line->len <= tp->cx) {
		while (line->len < tp->cx) {
			cell = line->cells + line->len;
			cell->character = tp->view.ascebc[' '];
			cell->highlight = tp->highlight;
			cell->f_color = tp->f_color;
			line->len++;
		}
		line->len++;
	}
	cell = line->cells + tp->cx;
	cell->character = tp->view.ascebc[(unsigned int) ch];
	cell->highlight = tp->highlight;
	cell->f_color = tp->f_color;
}

/*
 * Convert a tty3270_line to a 3270 data fragment usable for output.
 */
static void
tty3270_convert_line(struct tty3270 *tp, int line_nr)
{
	struct tty3270_line *line;
	struct tty3270_cell *cell;
	struct string *s, *n;
	unsigned char highlight;
	unsigned char f_color;
	char *cp;
	int flen, i;

	/* Determine how long the fragment will be. */
	flen = 3;		/* Prefix (TO_SBA). */
	line = tp->screen + line_nr;
	flen += line->len;
	highlight = TAX_RESET;
	f_color = TAC_RESET;
	for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
		if (cell->highlight != highlight) {
			flen += 3;	/* TO_SA to switch highlight. */
			highlight = cell->highlight;
		}
		if (cell->f_color != f_color) {
			flen += 3;	/* TO_SA to switch color. */
			f_color = cell->f_color;
		}
	}
	if (highlight != TAX_RESET)
		flen += 3;	/* TO_SA to reset hightlight. */
	if (f_color != TAC_RESET)
		flen += 3;	/* TO_SA to reset color. */
	if (line->len < tp->view.cols)
		flen += 4;	/* Postfix (TO_RA). */

	/* Find the line in the list. */
	i = tp->view.rows - 2 - line_nr;
	list_for_each_entry_reverse(s, &tp->lines, list)
		if (--i <= 0)
			break;
	/*
	 * Check if the line needs to get reallocated.
	 */
	if (s->len != flen) {
		/* Reallocate string. */
		n = tty3270_alloc_string(tp, flen);
		list_add(&n->list, &s->list);
		list_del_init(&s->list);
		if (!list_empty(&s->update))
			list_del_init(&s->update);
		free_string(&tp->freemem, s);
		s = n;
	}

	/* Write 3270 data fragment. */
	cp = s->string;
	*cp++ = TO_SBA;
	*cp++ = 0;
	*cp++ = 0;

	highlight = TAX_RESET;
	f_color = TAC_RESET;
	for (i = 0, cell = line->cells; i < line->len; i++, cell++) {
		if (cell->highlight != highlight) {
			*cp++ = TO_SA;
			*cp++ = TAT_EXTHI;
			*cp++ = cell->highlight;
			highlight = cell->highlight;
		}
		if (cell->f_color != f_color) {
			*cp++ = TO_SA;
			*cp++ = TAT_COLOR;
			*cp++ = cell->f_color;
			f_color = cell->f_color;
		}
		*cp++ = cell->character;
	}
	if (highlight != TAX_RESET) {
		*cp++ = TO_SA;
		*cp++ = TAT_EXTHI;
		*cp++ = TAX_RESET;
	}
	if (f_color != TAC_RESET) {
		*cp++ = TO_SA;
		*cp++ = TAT_COLOR;
		*cp++ = TAC_RESET;
	}
	if (line->len < tp->view.cols) {
		*cp++ = TO_RA;
		*cp++ = 0;
		*cp++ = 0;
		*cp++ = 0;
	}

	if (tp->nr_up + line_nr < tp->view.rows - 2) {
		/* Line is currently visible on screen. */
		tty3270_update_string(tp, s, line_nr);
		/* Add line to update list. */
		if (list_empty(&s->update)) {
			list_add_tail(&s->update, &tp->update);
			tp->update_flags |= TTY_UPDATE_LIST;
		}
	}
}

/*
 * Do carriage return.
 */
static void
tty3270_cr(struct tty3270 *tp)
{
	tp->cx = 0;
}

/*
 * Do line feed.
 */
static void
tty3270_lf(struct tty3270 *tp)
{
	struct tty3270_line temp;
	int i;

	tty3270_convert_line(tp, tp->cy);
	if (tp->cy < tp->view.rows - 3) {
		tp->cy++;
		return;
	}
	/* Last line just filled up. Add new, blank line. */
	tty3270_blank_line(tp);
	temp = tp->screen[0];
	temp.len = 0;
	for (i = 0; i < tp->view.rows - 3; i++)
		tp->screen[i] = tp->screen[i+1];
	tp->screen[tp->view.rows - 3] = temp;
	tty3270_rebuild_update(tp);
}

static void
tty3270_ri(struct tty3270 *tp)
{
	if (tp->cy > 0) {
	    tty3270_convert_line(tp, tp->cy);
	    tp->cy--;
	}
}

/*
 * Insert characters at current position.
 */
static void
tty3270_insert_characters(struct tty3270 *tp, int n)
{
	struct tty3270_line *line;
	int k;

	line = tp->screen + tp->cy;
	while (line->len < tp->cx) {
		line->cells[line->len].character = tp->view.ascebc[' '];
		line->cells[line->len].highlight = TAX_RESET;
		line->cells[line->len].f_color = TAC_RESET;
		line->len++;
	}
	if (n > tp->view.cols - tp->cx)
		n = tp->view.cols - tp->cx;
	k = min_t(int, line->len - tp->cx, tp->view.cols - tp->cx - n);
	while (k--)
		line->cells[tp->cx + n + k] = line->cells[tp->cx + k];
	line->len += n;
	if (line->len > tp->view.cols)
		line->len = tp->view.cols;
	while (n-- > 0) {
		line->cells[tp->cx + n].character = tp->view.ascebc[' '];
		line->cells[tp->cx + n].highlight = tp->highlight;
		line->cells[tp->cx + n].f_color = tp->f_color;
	}
}

/*
 * Delete characters at current position.
 */
static void
tty3270_delete_characters(struct tty3270 *tp, int n)
{
	struct tty3270_line *line;
	int i;

	line = tp->screen + tp->cy;
	if (line->len <= tp->cx)
		return;
	if (line->len - tp->cx <= n) {
		line->len = tp->cx;
		return;
	}
	for (i = tp->cx; i + n < line->len; i++)
		line->cells[i] = line->cells[i + n];
	line->len -= n;
}

/*
 * Erase characters at current position.
 */
static void
tty3270_erase_characters(struct tty3270 *tp, int n)
{
	struct tty3270_line *line;
	struct tty3270_cell *cell;

	line = tp->screen + tp->cy;
	while (line->len > tp->cx && n-- > 0) {
		cell = line->cells + tp->cx++;
		cell->character = ' ';
		cell->highlight = TAX_RESET;
		cell->f_color = TAC_RESET;
	}
	tp->cx += n;
	tp->cx = min_t(int, tp->cx, tp->view.cols - 1);
}

/*
 * Erase line, 3 different cases:
 *  Esc [ 0 K	Erase from current position to end of line inclusive
 *  Esc [ 1 K	Erase from beginning of line to current position inclusive
 *  Esc [ 2 K	Erase entire line (without moving cursor)
 */
static void
tty3270_erase_line(struct tty3270 *tp, int mode)
{
	struct tty3270_line *line;
	struct tty3270_cell *cell;
	int i;

	line = tp->screen + tp->cy;
	if (mode == 0)
		line->len = tp->cx;
	else if (mode == 1) {
		for (i = 0; i < tp->cx; i++) {
			cell = line->cells + i;
			cell->character = ' ';
			cell->highlight = TAX_RESET;
			cell->f_color = TAC_RESET;
		}
		if (line->len <= tp->cx)
			line->len = tp->cx + 1;
	} else if (mode == 2)
		line->len = 0;
	tty3270_convert_line(tp, tp->cy);
}

/*
 * Erase display, 3 different cases:
 *  Esc [ 0 J	Erase from current position to bottom of screen inclusive
 *  Esc [ 1 J	Erase from top of screen to current position inclusive
 *  Esc [ 2 J	Erase entire screen (without moving the cursor)
 */
static void
tty3270_erase_display(struct tty3270 *tp, int mode)
{
	int i;

	if (mode == 0) {
		tty3270_erase_line(tp, 0);
		for (i = tp->cy + 1; i < tp->view.rows - 2; i++) {
			tp->screen[i].len = 0;
			tty3270_convert_line(tp, i);
		}
	} else if (mode == 1) {
		for (i = 0; i < tp->cy; i++) {
			tp->screen[i].len = 0;
			tty3270_convert_line(tp, i);
		}
		tty3270_erase_line(tp, 1);
	} else if (mode == 2) {
		for (i = 0; i < tp->view.rows - 2; i++) {
			tp->screen[i].len = 0;
			tty3270_convert_line(tp, i);
		}
	}
	tty3270_rebuild_update(tp);
}

/*
 * Set attributes found in an escape sequence.
 *  Esc [ <attr> ; <attr> ; ... m
 */
static void
tty3270_set_attributes(struct tty3270 *tp)
{
	static unsigned char f_colors[] = {
		TAC_DEFAULT, TAC_RED, TAC_GREEN, TAC_YELLOW, TAC_BLUE,
		TAC_PINK, TAC_TURQ, TAC_WHITE, 0, TAC_DEFAULT
	};
	int i, attr;

	for (i = 0; i <= tp->esc_npar; i++) {
		attr = tp->esc_par[i];
		switch (attr) {
		case 0:		/* Reset */
			tp->highlight = TAX_RESET;
			tp->f_color = TAC_RESET;
			break;
		/* Highlight. */
		case 4:		/* Start underlining. */
			tp->highlight = TAX_UNDER;
			break;
		case 5:		/* Start blink. */
			tp->highlight = TAX_BLINK;
			break;
		case 7:		/* Start reverse. */
			tp->highlight = TAX_REVER;
			break;
		case 24:	/* End underlining */
			if (tp->highlight == TAX_UNDER)
				tp->highlight = TAX_RESET;
			break;
		case 25:	/* End blink. */
			if (tp->highlight == TAX_BLINK)
				tp->highlight = TAX_RESET;
			break;
		case 27:	/* End reverse. */
			if (tp->highlight == TAX_REVER)
				tp->highlight = TAX_RESET;
			break;
		/* Foreground color. */
		case 30:	/* Black */
		case 31:	/* Red */
		case 32:	/* Green */
		case 33:	/* Yellow */
		case 34:	/* Blue */
		case 35:	/* Magenta */
		case 36:	/* Cyan */
		case 37:	/* White */
		case 39:	/* Black */
			tp->f_color = f_colors[attr - 30];
			break;
		}
	}
}

static inline int
tty3270_getpar(struct tty3270 *tp, int ix)
{
	return (tp->esc_par[ix] > 0) ? tp->esc_par[ix] : 1;
}

static void
tty3270_goto_xy(struct tty3270 *tp, int cx, int cy)
{
	int max_cx = max(0, cx);
	int max_cy = max(0, cy);

	tp->cx = min_t(int, tp->view.cols - 1, max_cx);
	cy = min_t(int, tp->view.rows - 3, max_cy);
	if (cy != tp->cy) {
		tty3270_convert_line(tp, tp->cy);
		tp->cy = cy;
	}
}

/*
 * Process escape sequences. Known sequences:
 *  Esc 7			Save Cursor Position
 *  Esc 8			Restore Cursor Position
 *  Esc [ Pn ; Pn ; .. m	Set attributes
 *  Esc [ Pn ; Pn H		Cursor Position
 *  Esc [ Pn ; Pn f		Cursor Position
 *  Esc [ Pn A			Cursor Up
 *  Esc [ Pn B			Cursor Down
 *  Esc [ Pn C			Cursor Forward
 *  Esc [ Pn D			Cursor Backward
 *  Esc [ Pn G			Cursor Horizontal Absolute
 *  Esc [ Pn X			Erase Characters
 *  Esc [ Ps J			Erase in Display
 *  Esc [ Ps K			Erase in Line
 * // FIXME: add all the new ones.
 *
 *  Pn is a numeric parameter, a string of zero or more decimal digits.
 *  Ps is a selective parameter.
 */
static void
tty3270_escape_sequence(struct tty3270 *tp, char ch)
{
	enum { ESnormal, ESesc, ESsquare, ESgetpars };

	if (tp->esc_state == ESnormal) {
		if (ch == 0x1b)
			/* Starting new escape sequence. */
			tp->esc_state = ESesc;
		return;
	}
	if (tp->esc_state == ESesc) {
		tp->esc_state = ESnormal;
		switch (ch) {
		case '[':
			tp->esc_state = ESsquare;
			break;
		case 'E':
			tty3270_cr(tp);
			tty3270_lf(tp);
			break;
		case 'M':
			tty3270_ri(tp);
			break;
		case 'D':
			tty3270_lf(tp);
			break;
		case 'Z':		/* Respond ID. */
			kbd_puts_queue(&tp->port, "\033[?6c");
			break;
		case '7':		/* Save cursor position. */
			tp->saved_cx = tp->cx;
			tp->saved_cy = tp->cy;
			tp->saved_highlight = tp->highlight;
			tp->saved_f_color = tp->f_color;
			break;
		case '8':		/* Restore cursor position. */
			tty3270_convert_line(tp, tp->cy);
			tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
			tp->highlight = tp->saved_highlight;
			tp->f_color = tp->saved_f_color;
			break;
		case 'c':		/* Reset terminal. */
			tp->cx = tp->saved_cx = 0;
			tp->cy = tp->saved_cy = 0;
			tp->highlight = tp->saved_highlight = TAX_RESET;
			tp->f_color = tp->saved_f_color = TAC_RESET;
			tty3270_erase_display(tp, 2);
			break;
		}
		return;
	}
	if (tp->esc_state == ESsquare) {
		tp->esc_state = ESgetpars;
		memset(tp->esc_par, 0, sizeof(tp->esc_par));
		tp->esc_npar = 0;
		tp->esc_ques = (ch == '?');
		if (tp->esc_ques)
			return;
	}
	if (tp->esc_state == ESgetpars) {
		if (ch == ';' && tp->esc_npar < ESCAPE_NPAR - 1) {
			tp->esc_npar++;
			return;
		}
		if (ch >= '0' && ch <= '9') {
			tp->esc_par[tp->esc_npar] *= 10;
			tp->esc_par[tp->esc_npar] += ch - '0';
			return;
		}
	}
	tp->esc_state = ESnormal;
	if (ch == 'n' && !tp->esc_ques) {
		if (tp->esc_par[0] == 5)		/* Status report. */
			kbd_puts_queue(&tp->port, "\033[0n");
		else if (tp->esc_par[0] == 6) {	/* Cursor report. */
			char buf[40];
			sprintf(buf, "\033[%d;%dR", tp->cy + 1, tp->cx + 1);
			kbd_puts_queue(&tp->port, buf);
		}
		return;
	}
	if (tp->esc_ques)
		return;
	switch (ch) {
	case 'm':
		tty3270_set_attributes(tp);
		break;
	case 'H':	/* Set cursor position. */
	case 'f':
		tty3270_goto_xy(tp, tty3270_getpar(tp, 1) - 1,
				tty3270_getpar(tp, 0) - 1);
		break;
	case 'd':	/* Set y position. */
		tty3270_goto_xy(tp, tp->cx, tty3270_getpar(tp, 0) - 1);
		break;
	case 'A':	/* Cursor up. */
	case 'F':
		tty3270_goto_xy(tp, tp->cx, tp->cy - tty3270_getpar(tp, 0));
		break;
	case 'B':	/* Cursor down. */
	case 'e':
	case 'E':
		tty3270_goto_xy(tp, tp->cx, tp->cy + tty3270_getpar(tp, 0));
		break;
	case 'C':	/* Cursor forward. */
	case 'a':
		tty3270_goto_xy(tp, tp->cx + tty3270_getpar(tp, 0), tp->cy);
		break;
	case 'D':	/* Cursor backward. */
		tty3270_goto_xy(tp, tp->cx - tty3270_getpar(tp, 0), tp->cy);
		break;
	case 'G':	/* Set x position. */
	case '`':
		tty3270_goto_xy(tp, tty3270_getpar(tp, 0), tp->cy);
		break;
	case 'X':	/* Erase Characters. */
		tty3270_erase_characters(tp, tty3270_getpar(tp, 0));
		break;
	case 'J':	/* Erase display. */
		tty3270_erase_display(tp, tp->esc_par[0]);
		break;
	case 'K':	/* Erase line. */
		tty3270_erase_line(tp, tp->esc_par[0]);
		break;
	case 'P':	/* Delete characters. */
		tty3270_delete_characters(tp, tty3270_getpar(tp, 0));
		break;
	case '@':	/* Insert characters. */
		tty3270_insert_characters(tp, tty3270_getpar(tp, 0));
		break;
	case 's':	/* Save cursor position. */
		tp->saved_cx = tp->cx;
		tp->saved_cy = tp->cy;
		tp->saved_highlight = tp->highlight;
		tp->saved_f_color = tp->f_color;
		break;
	case 'u':	/* Restore cursor position. */
		tty3270_convert_line(tp, tp->cy);
		tty3270_goto_xy(tp, tp->saved_cx, tp->saved_cy);
		tp->highlight = tp->saved_highlight;
		tp->f_color = tp->saved_f_color;
		break;
	}
}

/*
 * String write routine for 3270 ttys
 */
static void
tty3270_do_write(struct tty3270 *tp, struct tty_struct *tty,
		const unsigned char *buf, int count)
{
	int i_msg, i;

	spin_lock_bh(&tp->view.lock);
	for (i_msg = 0; !tty->stopped && i_msg < count; i_msg++) {
		if (tp->esc_state != 0) {
			/* Continue escape sequence. */
			tty3270_escape_sequence(tp, buf[i_msg]);
			continue;
		}

		switch (buf[i_msg]) {
		case 0x07:		/* '\a' -- Alarm */
			tp->wcc |= TW_PLUSALARM;
			break;
		case 0x08:		/* Backspace. */
			if (tp->cx > 0) {
				tp->cx--;
				tty3270_put_character(tp, ' ');
			}
			break;
		case 0x09:		/* '\t' -- Tabulate */
			for (i = tp->cx % 8; i < 8; i++) {
				if (tp->cx >= tp->view.cols) {
					tty3270_cr(tp);
					tty3270_lf(tp);
					break;
				}
				tty3270_put_character(tp, ' ');
				tp->cx++;
			}
			break;
		case 0x0a:		/* '\n' -- New Line */
			tty3270_cr(tp);
			tty3270_lf(tp);
			break;
		case 0x0c:		/* '\f' -- Form Feed */
			tty3270_erase_display(tp, 2);
			tp->cx = tp->cy = 0;
			break;
		case 0x0d:		/* '\r' -- Carriage Return */
			tp->cx = 0;
			break;
		case 0x0f:		/* SuSE "exit alternate mode" */
			break;
		case 0x1b:		/* Start escape sequence. */
			tty3270_escape_sequence(tp, buf[i_msg]);
			break;
		default:		/* Insert normal character. */
			if (tp->cx >= tp->view.cols) {
				tty3270_cr(tp);
				tty3270_lf(tp);
			}
			tty3270_put_character(tp, buf[i_msg]);
			tp->cx++;
			break;
		}
	}
	/* Convert current line to 3270 data fragment. */
	tty3270_convert_line(tp, tp->cy);

	/* Setup timer to update display after 1/10 second */
	if (!timer_pending(&tp->timer))
		tty3270_set_timer(tp, HZ/10);

	spin_unlock_bh(&tp->view.lock);
}

/*
 * String write routine for 3270 ttys
 */
static int
tty3270_write(struct tty_struct * tty,
	      const unsigned char *buf, int count)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return 0;
	if (tp->char_count > 0) {
		tty3270_do_write(tp, tty, tp->char_buf, tp->char_count);
		tp->char_count = 0;
	}
	tty3270_do_write(tp, tty, buf, count);
	return count;
}

/*
 * Put single characters to the ttys character buffer
 */
static int tty3270_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp || tp->char_count >= TTY3270_CHAR_BUF_SIZE)
		return 0;
	tp->char_buf[tp->char_count++] = ch;
	return 1;
}

/*
 * Flush all characters from the ttys characeter buffer put there
 * by tty3270_put_char.
 */
static void
tty3270_flush_chars(struct tty_struct *tty)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return;
	if (tp->char_count > 0) {
		tty3270_do_write(tp, tty, tp->char_buf, tp->char_count);
		tp->char_count = 0;
	}
}

/*
 * Returns the number of characters in the output buffer. This is
 * used in tty_wait_until_sent to wait until all characters have
 * appeared on the screen.
 */
static int
tty3270_chars_in_buffer(struct tty_struct *tty)
{
	return 0;
}

static void
tty3270_flush_buffer(struct tty_struct *tty)
{
}

/*
 * Check for visible/invisible input switches
 */
static void
tty3270_set_termios(struct tty_struct *tty, struct ktermios *old)
{
	struct tty3270 *tp;
	int new;

	tp = tty->driver_data;
	if (!tp)
		return;
	spin_lock_bh(&tp->view.lock);
	if (L_ICANON(tty)) {
		new = L_ECHO(tty) ? TF_INPUT: TF_INPUTN;
		if (new != tp->inattr) {
			tp->inattr = new;
			tty3270_update_prompt(tp, NULL, 0);
			tty3270_set_timer(tp, 1);
		}
	}
	spin_unlock_bh(&tp->view.lock);
}

/*
 * Disable reading from a 3270 tty
 */
static void
tty3270_throttle(struct tty_struct * tty)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return;
	tp->throttle = 1;
}

/*
 * Enable reading from a 3270 tty
 */
static void
tty3270_unthrottle(struct tty_struct * tty)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return;
	tp->throttle = 0;
	if (tp->attn)
		tty3270_issue_read(tp, 1);
}

/*
 * Hang up the tty device.
 */
static void
tty3270_hangup(struct tty_struct *tty)
{
	// FIXME: implement
}

static void
tty3270_wait_until_sent(struct tty_struct *tty, int timeout)
{
}

static int tty3270_ioctl(struct tty_struct *tty, unsigned int cmd,
			 unsigned long arg)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return -ENODEV;
	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;
	return kbd_ioctl(tp->kbd, cmd, arg);
}

#ifdef CONFIG_COMPAT
static long tty3270_compat_ioctl(struct tty_struct *tty,
				 unsigned int cmd, unsigned long arg)
{
	struct tty3270 *tp;

	tp = tty->driver_data;
	if (!tp)
		return -ENODEV;
	if (tty->flags & (1 << TTY_IO_ERROR))
		return -EIO;
	return kbd_ioctl(tp->kbd, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static const struct tty_operations tty3270_ops = {
	.install = tty3270_install,
	.cleanup = tty3270_cleanup,
	.open = tty3270_open,
	.close = tty3270_close,
	.write = tty3270_write,
	.put_char = tty3270_put_char,
	.flush_chars = tty3270_flush_chars,
	.write_room = tty3270_write_room,
	.chars_in_buffer = tty3270_chars_in_buffer,
	.flush_buffer = tty3270_flush_buffer,
	.throttle = tty3270_throttle,
	.unthrottle = tty3270_unthrottle,
	.hangup = tty3270_hangup,
	.wait_until_sent = tty3270_wait_until_sent,
	.ioctl = tty3270_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = tty3270_compat_ioctl,
#endif
	.set_termios = tty3270_set_termios
};

void tty3270_create_cb(int minor)
{
	tty_register_device(tty3270_driver, minor, NULL);
}

void tty3270_destroy_cb(int minor)
{
	tty_unregister_device(tty3270_driver, minor);
}

struct raw3270_notifier tty3270_notifier =
{
	.create = tty3270_create_cb,
	.destroy = tty3270_destroy_cb,
};

/*
 * 3270 tty registration code called from tty_init().
 * Most kernel services (incl. kmalloc) are available at this poimt.
 */
static int __init tty3270_init(void)
{
	struct tty_driver *driver;
	int ret;

	driver = tty_alloc_driver(RAW3270_MAXDEVS,
				  TTY_DRIVER_REAL_RAW |
				  TTY_DRIVER_DYNAMIC_DEV |
				  TTY_DRIVER_RESET_TERMIOS);
	if (IS_ERR(driver))
		return PTR_ERR(driver);

	/*
	 * Initialize the tty_driver structure
	 * Entries in tty3270_driver that are NOT initialized:
	 * proc_entry, set_termios, flush_buffer, set_ldisc, write_proc
	 */
	driver->driver_name = "tty3270";
	driver->name = "3270/tty";
	driver->major = IBM_TTY3270_MAJOR;
	driver->minor_start = 0;
	driver->type = TTY_DRIVER_TYPE_SYSTEM;
	driver->subtype = SYSTEM_TYPE_TTY;
	driver->init_termios = tty_std_termios;
	tty_set_operations(driver, &tty3270_ops);
	ret = tty_register_driver(driver);
	if (ret) {
		put_tty_driver(driver);
		return ret;
	}
	tty3270_driver = driver;
	raw3270_register_notifier(&tty3270_notifier);
	return 0;
}

static void __exit
tty3270_exit(void)
{
	struct tty_driver *driver;

	raw3270_unregister_notifier(&tty3270_notifier);
	driver = tty3270_driver;
	tty3270_driver = NULL;
	tty_unregister_driver(driver);
	put_tty_driver(driver);
	tty3270_del_views();
}

MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(IBM_TTY3270_MAJOR);

module_init(tty3270_init);
module_exit(tty3270_exit);