aboutsummaryrefslogtreecommitdiff
path: root/drivers/s390/cio/device.c
blob: 95b92dfec5a815435630b1e7692591aa2dedad0c (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
1861
1862
1863
1864
1865
1866
/*
 *  drivers/s390/cio/device.c
 *  bus driver for ccw devices
 *
 *    Copyright IBM Corp. 2002,2008
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *		 Cornelia Huck (cornelia.huck@de.ibm.com)
 *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/device.h>
#include <linux/workqueue.h>
#include <linux/timer.h>

#include <asm/ccwdev.h>
#include <asm/cio.h>
#include <asm/param.h>		/* HZ */
#include <asm/cmb.h>
#include <asm/isc.h>

#include "chp.h"
#include "cio.h"
#include "cio_debug.h"
#include "css.h"
#include "device.h"
#include "ioasm.h"
#include "io_sch.h"
#include "blacklist.h"

static struct timer_list recovery_timer;
static DEFINE_SPINLOCK(recovery_lock);
static int recovery_phase;
static const unsigned long recovery_delay[] = { 3, 30, 300 };

/******************* bus type handling ***********************/

/* The Linux driver model distinguishes between a bus type and
 * the bus itself. Of course we only have one channel
 * subsystem driver and one channel system per machine, but
 * we still use the abstraction. T.R. says it's a good idea. */
static int
ccw_bus_match (struct device * dev, struct device_driver * drv)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_driver *cdrv = to_ccwdrv(drv);
	const struct ccw_device_id *ids = cdrv->ids, *found;

	if (!ids)
		return 0;

	found = ccw_device_id_match(ids, &cdev->id);
	if (!found)
		return 0;

	cdev->id.driver_info = found->driver_info;

	return 1;
}

/* Store modalias string delimited by prefix/suffix string into buffer with
 * specified size. Return length of resulting string (excluding trailing '\0')
 * even if string doesn't fit buffer (snprintf semantics). */
static int snprint_alias(char *buf, size_t size,
			 struct ccw_device_id *id, const char *suffix)
{
	int len;

	len = snprintf(buf, size, "ccw:t%04Xm%02X", id->cu_type, id->cu_model);
	if (len > size)
		return len;
	buf += len;
	size -= len;

	if (id->dev_type != 0)
		len += snprintf(buf, size, "dt%04Xdm%02X%s", id->dev_type,
				id->dev_model, suffix);
	else
		len += snprintf(buf, size, "dtdm%s", suffix);

	return len;
}

/* Set up environment variables for ccw device uevent. Return 0 on success,
 * non-zero otherwise. */
static int ccw_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_id *id = &(cdev->id);
	int ret;
	char modalias_buf[30];

	/* CU_TYPE= */
	ret = add_uevent_var(env, "CU_TYPE=%04X", id->cu_type);
	if (ret)
		return ret;

	/* CU_MODEL= */
	ret = add_uevent_var(env, "CU_MODEL=%02X", id->cu_model);
	if (ret)
		return ret;

	/* The next two can be zero, that's ok for us */
	/* DEV_TYPE= */
	ret = add_uevent_var(env, "DEV_TYPE=%04X", id->dev_type);
	if (ret)
		return ret;

	/* DEV_MODEL= */
	ret = add_uevent_var(env, "DEV_MODEL=%02X", id->dev_model);
	if (ret)
		return ret;

	/* MODALIAS=  */
	snprint_alias(modalias_buf, sizeof(modalias_buf), id, "");
	ret = add_uevent_var(env, "MODALIAS=%s", modalias_buf);
	return ret;
}

struct bus_type ccw_bus_type;

static void io_subchannel_irq(struct subchannel *);
static int io_subchannel_probe(struct subchannel *);
static int io_subchannel_remove(struct subchannel *);
static void io_subchannel_shutdown(struct subchannel *);
static int io_subchannel_sch_event(struct subchannel *, int);
static int io_subchannel_chp_event(struct subchannel *, struct chp_link *,
				   int);

static struct css_device_id io_subchannel_ids[] = {
	{ .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
	{ /* end of list */ },
};
MODULE_DEVICE_TABLE(css, io_subchannel_ids);

static struct css_driver io_subchannel_driver = {
	.owner = THIS_MODULE,
	.subchannel_type = io_subchannel_ids,
	.name = "io_subchannel",
	.irq = io_subchannel_irq,
	.sch_event = io_subchannel_sch_event,
	.chp_event = io_subchannel_chp_event,
	.probe = io_subchannel_probe,
	.remove = io_subchannel_remove,
	.shutdown = io_subchannel_shutdown,
};

struct workqueue_struct *ccw_device_work;
wait_queue_head_t ccw_device_init_wq;
atomic_t ccw_device_init_count;

static void recovery_func(unsigned long data);

static int __init
init_ccw_bus_type (void)
{
	int ret;

	init_waitqueue_head(&ccw_device_init_wq);
	atomic_set(&ccw_device_init_count, 0);
	setup_timer(&recovery_timer, recovery_func, 0);

	ccw_device_work = create_singlethread_workqueue("cio");
	if (!ccw_device_work)
		return -ENOMEM; /* FIXME: better errno ? */
	slow_path_wq = create_singlethread_workqueue("kslowcrw");
	if (!slow_path_wq) {
		ret = -ENOMEM; /* FIXME: better errno ? */
		goto out_err;
	}
	if ((ret = bus_register (&ccw_bus_type)))
		goto out_err;

	ret = css_driver_register(&io_subchannel_driver);
	if (ret)
		goto out_err;

	wait_event(ccw_device_init_wq,
		   atomic_read(&ccw_device_init_count) == 0);
	flush_workqueue(ccw_device_work);
	return 0;
out_err:
	if (ccw_device_work)
		destroy_workqueue(ccw_device_work);
	if (slow_path_wq)
		destroy_workqueue(slow_path_wq);
	return ret;
}

static void __exit
cleanup_ccw_bus_type (void)
{
	css_driver_unregister(&io_subchannel_driver);
	bus_unregister(&ccw_bus_type);
	destroy_workqueue(ccw_device_work);
}

subsys_initcall(init_ccw_bus_type);
module_exit(cleanup_ccw_bus_type);

/************************ device handling **************************/

/*
 * A ccw_device has some interfaces in sysfs in addition to the
 * standard ones.
 * The following entries are designed to export the information which
 * resided in 2.4 in /proc/subchannels. Subchannel and device number
 * are obvious, so they don't have an entry :)
 * TODO: Split chpids and pimpampom up? Where is "in use" in the tree?
 */
static ssize_t
chpids_show (struct device * dev, struct device_attribute *attr, char * buf)
{
	struct subchannel *sch = to_subchannel(dev);
	struct chsc_ssd_info *ssd = &sch->ssd_info;
	ssize_t ret = 0;
	int chp;
	int mask;

	for (chp = 0; chp < 8; chp++) {
		mask = 0x80 >> chp;
		if (ssd->path_mask & mask)
			ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
		else
			ret += sprintf(buf + ret, "00 ");
	}
	ret += sprintf (buf+ret, "\n");
	return min((ssize_t)PAGE_SIZE, ret);
}

static ssize_t
pimpampom_show (struct device * dev, struct device_attribute *attr, char * buf)
{
	struct subchannel *sch = to_subchannel(dev);
	struct pmcw *pmcw = &sch->schib.pmcw;

	return sprintf (buf, "%02x %02x %02x\n",
			pmcw->pim, pmcw->pam, pmcw->pom);
}

static ssize_t
devtype_show (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_id *id = &(cdev->id);

	if (id->dev_type != 0)
		return sprintf(buf, "%04x/%02x\n",
				id->dev_type, id->dev_model);
	else
		return sprintf(buf, "n/a\n");
}

static ssize_t
cutype_show (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_id *id = &(cdev->id);

	return sprintf(buf, "%04x/%02x\n",
		       id->cu_type, id->cu_model);
}

static ssize_t
modalias_show (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_id *id = &(cdev->id);
	int len;

	len = snprint_alias(buf, PAGE_SIZE, id, "\n");

	return len > PAGE_SIZE ? PAGE_SIZE : len;
}

static ssize_t
online_show (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);

	return sprintf(buf, cdev->online ? "1\n" : "0\n");
}

int ccw_device_is_orphan(struct ccw_device *cdev)
{
	return sch_is_pseudo_sch(to_subchannel(cdev->dev.parent));
}

static void ccw_device_unregister(struct ccw_device *cdev)
{
	if (test_and_clear_bit(1, &cdev->private->registered))
		device_del(&cdev->dev);
}

static void ccw_device_remove_orphan_cb(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	ccw_device_unregister(cdev);
	put_device(&cdev->dev);
	/* Release cdev reference for workqueue processing. */
	put_device(&cdev->dev);
}

static void ccw_device_call_sch_unregister(struct work_struct *work);

static void
ccw_device_remove_disconnected(struct ccw_device *cdev)
{
	unsigned long flags;

	/*
	 * Forced offline in disconnected state means
	 * 'throw away device'.
	 */
	/* Get cdev reference for workqueue processing. */
	if (!get_device(&cdev->dev))
		return;
	if (ccw_device_is_orphan(cdev)) {
		/*
		 * Deregister ccw device.
		 * Unfortunately, we cannot do this directly from the
		 * attribute method.
		 */
		spin_lock_irqsave(cdev->ccwlock, flags);
		cdev->private->state = DEV_STATE_NOT_OPER;
		spin_unlock_irqrestore(cdev->ccwlock, flags);
		PREPARE_WORK(&cdev->private->kick_work,
				ccw_device_remove_orphan_cb);
	} else
		/* Deregister subchannel, which will kill the ccw device. */
		PREPARE_WORK(&cdev->private->kick_work,
				ccw_device_call_sch_unregister);
	queue_work(slow_path_wq, &cdev->private->kick_work);
}

/**
 * ccw_device_set_offline() - disable a ccw device for I/O
 * @cdev: target ccw device
 *
 * This function calls the driver's set_offline() function for @cdev, if
 * given, and then disables @cdev.
 * Returns:
 *   %0 on success and a negative error value on failure.
 * Context:
 *  enabled, ccw device lock not held
 */
int ccw_device_set_offline(struct ccw_device *cdev)
{
	int ret;

	if (!cdev)
		return -ENODEV;
	if (!cdev->online || !cdev->drv)
		return -EINVAL;

	if (cdev->drv->set_offline) {
		ret = cdev->drv->set_offline(cdev);
		if (ret != 0)
			return ret;
	}
	cdev->online = 0;
	spin_lock_irq(cdev->ccwlock);
	ret = ccw_device_offline(cdev);
	if (ret == -ENODEV) {
		if (cdev->private->state != DEV_STATE_NOT_OPER) {
			cdev->private->state = DEV_STATE_OFFLINE;
			dev_fsm_event(cdev, DEV_EVENT_NOTOPER);
		}
		spin_unlock_irq(cdev->ccwlock);
		return ret;
	}
	spin_unlock_irq(cdev->ccwlock);
	if (ret == 0)
		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
	else {
		CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
			      "device 0.%x.%04x\n",
			      ret, cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno);
		cdev->online = 1;
	}
 	return ret;
}

/**
 * ccw_device_set_online() - enable a ccw device for I/O
 * @cdev: target ccw device
 *
 * This function first enables @cdev and then calls the driver's set_online()
 * function for @cdev, if given. If set_online() returns an error, @cdev is
 * disabled again.
 * Returns:
 *   %0 on success and a negative error value on failure.
 * Context:
 *  enabled, ccw device lock not held
 */
int ccw_device_set_online(struct ccw_device *cdev)
{
	int ret;

	if (!cdev)
		return -ENODEV;
	if (cdev->online || !cdev->drv)
		return -EINVAL;

	spin_lock_irq(cdev->ccwlock);
	ret = ccw_device_online(cdev);
	spin_unlock_irq(cdev->ccwlock);
	if (ret == 0)
		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
	else {
		CIO_MSG_EVENT(0, "ccw_device_online returned %d, "
			      "device 0.%x.%04x\n",
			      ret, cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno);
		return ret;
	}
	if (cdev->private->state != DEV_STATE_ONLINE)
		return -ENODEV;
	if (!cdev->drv->set_online || cdev->drv->set_online(cdev) == 0) {
		cdev->online = 1;
		return 0;
	}
	spin_lock_irq(cdev->ccwlock);
	ret = ccw_device_offline(cdev);
	spin_unlock_irq(cdev->ccwlock);
	if (ret == 0)
		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
	else
		CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
			      "device 0.%x.%04x\n",
			      ret, cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno);
	return (ret == 0) ? -ENODEV : ret;
}

static void online_store_handle_offline(struct ccw_device *cdev)
{
	if (cdev->private->state == DEV_STATE_DISCONNECTED)
		ccw_device_remove_disconnected(cdev);
	else if (cdev->drv && cdev->drv->set_offline)
		ccw_device_set_offline(cdev);
}

static int online_store_recog_and_online(struct ccw_device *cdev)
{
	int ret;

	/* Do device recognition, if needed. */
	if (cdev->id.cu_type == 0) {
		ret = ccw_device_recognition(cdev);
		if (ret) {
			CIO_MSG_EVENT(0, "Couldn't start recognition "
				      "for device 0.%x.%04x (ret=%d)\n",
				      cdev->private->dev_id.ssid,
				      cdev->private->dev_id.devno, ret);
			return ret;
		}
		wait_event(cdev->private->wait_q,
			   cdev->private->flags.recog_done);
	}
	if (cdev->drv && cdev->drv->set_online)
		ccw_device_set_online(cdev);
	return 0;
}
static int online_store_handle_online(struct ccw_device *cdev, int force)
{
	int ret;

	ret = online_store_recog_and_online(cdev);
	if (ret)
		return ret;
	if (force && cdev->private->state == DEV_STATE_BOXED) {
		ret = ccw_device_stlck(cdev);
		if (ret)
			return ret;
		if (cdev->id.cu_type == 0)
			cdev->private->state = DEV_STATE_NOT_OPER;
		online_store_recog_and_online(cdev);
	}
	return 0;
}

static ssize_t online_store (struct device *dev, struct device_attribute *attr,
			     const char *buf, size_t count)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	int force, ret;
	unsigned long i;

	if (atomic_cmpxchg(&cdev->private->onoff, 0, 1) != 0)
		return -EAGAIN;

	if (cdev->drv && !try_module_get(cdev->drv->owner)) {
		atomic_set(&cdev->private->onoff, 0);
		return -EINVAL;
	}
	if (!strncmp(buf, "force\n", count)) {
		force = 1;
		i = 1;
		ret = 0;
	} else {
		force = 0;
		ret = strict_strtoul(buf, 16, &i);
	}
	if (ret)
		goto out;
	switch (i) {
	case 0:
		online_store_handle_offline(cdev);
		ret = count;
		break;
	case 1:
		ret = online_store_handle_online(cdev, force);
		if (!ret)
			ret = count;
		break;
	default:
		ret = -EINVAL;
	}
out:
	if (cdev->drv)
		module_put(cdev->drv->owner);
	atomic_set(&cdev->private->onoff, 0);
	return ret;
}

static ssize_t
available_show (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct subchannel *sch;

	if (ccw_device_is_orphan(cdev))
		return sprintf(buf, "no device\n");
	switch (cdev->private->state) {
	case DEV_STATE_BOXED:
		return sprintf(buf, "boxed\n");
	case DEV_STATE_DISCONNECTED:
	case DEV_STATE_DISCONNECTED_SENSE_ID:
	case DEV_STATE_NOT_OPER:
		sch = to_subchannel(dev->parent);
		if (!sch->lpm)
			return sprintf(buf, "no path\n");
		else
			return sprintf(buf, "no device\n");
	default:
		/* All other states considered fine. */
		return sprintf(buf, "good\n");
	}
}

static DEVICE_ATTR(chpids, 0444, chpids_show, NULL);
static DEVICE_ATTR(pimpampom, 0444, pimpampom_show, NULL);
static DEVICE_ATTR(devtype, 0444, devtype_show, NULL);
static DEVICE_ATTR(cutype, 0444, cutype_show, NULL);
static DEVICE_ATTR(modalias, 0444, modalias_show, NULL);
static DEVICE_ATTR(online, 0644, online_show, online_store);
static DEVICE_ATTR(availability, 0444, available_show, NULL);

static struct attribute *io_subchannel_attrs[] = {
	&dev_attr_chpids.attr,
	&dev_attr_pimpampom.attr,
	NULL,
};

static struct attribute_group io_subchannel_attr_group = {
	.attrs = io_subchannel_attrs,
};

static struct attribute * ccwdev_attrs[] = {
	&dev_attr_devtype.attr,
	&dev_attr_cutype.attr,
	&dev_attr_modalias.attr,
	&dev_attr_online.attr,
	&dev_attr_cmb_enable.attr,
	&dev_attr_availability.attr,
	NULL,
};

static struct attribute_group ccwdev_attr_group = {
	.attrs = ccwdev_attrs,
};

static struct attribute_group *ccwdev_attr_groups[] = {
	&ccwdev_attr_group,
	NULL,
};

/* this is a simple abstraction for device_register that sets the
 * correct bus type and adds the bus specific files */
static int ccw_device_register(struct ccw_device *cdev)
{
	struct device *dev = &cdev->dev;
	int ret;

	dev->bus = &ccw_bus_type;

	if ((ret = device_add(dev)))
		return ret;

	set_bit(1, &cdev->private->registered);
	return ret;
}

struct match_data {
	struct ccw_dev_id dev_id;
	struct ccw_device * sibling;
};

static int
match_devno(struct device * dev, void * data)
{
	struct match_data * d = data;
	struct ccw_device * cdev;

	cdev = to_ccwdev(dev);
	if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
	    !ccw_device_is_orphan(cdev) &&
	    ccw_dev_id_is_equal(&cdev->private->dev_id, &d->dev_id) &&
	    (cdev != d->sibling))
		return 1;
	return 0;
}

static struct ccw_device * get_disc_ccwdev_by_dev_id(struct ccw_dev_id *dev_id,
						     struct ccw_device *sibling)
{
	struct device *dev;
	struct match_data data;

	data.dev_id = *dev_id;
	data.sibling = sibling;
	dev = bus_find_device(&ccw_bus_type, NULL, &data, match_devno);

	return dev ? to_ccwdev(dev) : NULL;
}

static int match_orphan(struct device *dev, void *data)
{
	struct ccw_dev_id *dev_id;
	struct ccw_device *cdev;

	dev_id = data;
	cdev = to_ccwdev(dev);
	return ccw_dev_id_is_equal(&cdev->private->dev_id, dev_id);
}

static struct ccw_device *
get_orphaned_ccwdev_by_dev_id(struct channel_subsystem *css,
			      struct ccw_dev_id *dev_id)
{
	struct device *dev;

	dev = device_find_child(&css->pseudo_subchannel->dev, dev_id,
				match_orphan);

	return dev ? to_ccwdev(dev) : NULL;
}

static void
ccw_device_add_changed(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	if (device_add(&cdev->dev)) {
		put_device(&cdev->dev);
		return;
	}
	set_bit(1, &cdev->private->registered);
}

void ccw_device_do_unreg_rereg(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;
	struct subchannel *sch;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	sch = to_subchannel(cdev->dev.parent);

	ccw_device_unregister(cdev);
	PREPARE_WORK(&cdev->private->kick_work,
		     ccw_device_add_changed);
	queue_work(ccw_device_work, &cdev->private->kick_work);
}

static void
ccw_device_release(struct device *dev)
{
	struct ccw_device *cdev;

	cdev = to_ccwdev(dev);
	kfree(cdev->private);
	kfree(cdev);
}

static struct ccw_device * io_subchannel_allocate_dev(struct subchannel *sch)
{
	struct ccw_device *cdev;

	cdev  = kzalloc(sizeof(*cdev), GFP_KERNEL);
	if (cdev) {
		cdev->private = kzalloc(sizeof(struct ccw_device_private),
					GFP_KERNEL | GFP_DMA);
		if (cdev->private)
			return cdev;
	}
	kfree(cdev);
	return ERR_PTR(-ENOMEM);
}

static int io_subchannel_initialize_dev(struct subchannel *sch,
					struct ccw_device *cdev)
{
	cdev->private->cdev = cdev;
	atomic_set(&cdev->private->onoff, 0);
	cdev->dev.parent = &sch->dev;
	cdev->dev.release = ccw_device_release;
	INIT_WORK(&cdev->private->kick_work, NULL);
	cdev->dev.groups = ccwdev_attr_groups;
	/* Do first half of device_register. */
	device_initialize(&cdev->dev);
	if (!get_device(&sch->dev)) {
		if (cdev->dev.release)
			cdev->dev.release(&cdev->dev);
		return -ENODEV;
	}
	return 0;
}

static struct ccw_device * io_subchannel_create_ccwdev(struct subchannel *sch)
{
	struct ccw_device *cdev;
	int ret;

	cdev = io_subchannel_allocate_dev(sch);
	if (!IS_ERR(cdev)) {
		ret = io_subchannel_initialize_dev(sch, cdev);
		if (ret) {
			kfree(cdev);
			cdev = ERR_PTR(ret);
		}
	}
	return cdev;
}

static int io_subchannel_recog(struct ccw_device *, struct subchannel *);

static void sch_attach_device(struct subchannel *sch,
			      struct ccw_device *cdev)
{
	css_update_ssd_info(sch);
	spin_lock_irq(sch->lock);
	sch_set_cdev(sch, cdev);
	cdev->private->schid = sch->schid;
	cdev->ccwlock = sch->lock;
	ccw_device_trigger_reprobe(cdev);
	spin_unlock_irq(sch->lock);
}

static void sch_attach_disconnected_device(struct subchannel *sch,
					   struct ccw_device *cdev)
{
	struct subchannel *other_sch;
	int ret;

	other_sch = to_subchannel(get_device(cdev->dev.parent));
	ret = device_move(&cdev->dev, &sch->dev);
	if (ret) {
		CIO_MSG_EVENT(0, "Moving disconnected device 0.%x.%04x failed "
			      "(ret=%d)!\n", cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno, ret);
		put_device(&other_sch->dev);
		return;
	}
	sch_set_cdev(other_sch, NULL);
	/* No need to keep a subchannel without ccw device around. */
	css_sch_device_unregister(other_sch);
	put_device(&other_sch->dev);
	sch_attach_device(sch, cdev);
}

static void sch_attach_orphaned_device(struct subchannel *sch,
				       struct ccw_device *cdev)
{
	int ret;

	/* Try to move the ccw device to its new subchannel. */
	ret = device_move(&cdev->dev, &sch->dev);
	if (ret) {
		CIO_MSG_EVENT(0, "Moving device 0.%x.%04x from orphanage "
			      "failed (ret=%d)!\n",
			      cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno, ret);
		return;
	}
	sch_attach_device(sch, cdev);
}

static void sch_create_and_recog_new_device(struct subchannel *sch)
{
	struct ccw_device *cdev;

	/* Need to allocate a new ccw device. */
	cdev = io_subchannel_create_ccwdev(sch);
	if (IS_ERR(cdev)) {
		/* OK, we did everything we could... */
		css_sch_device_unregister(sch);
		return;
	}
	spin_lock_irq(sch->lock);
	sch_set_cdev(sch, cdev);
	spin_unlock_irq(sch->lock);
	/* Start recognition for the new ccw device. */
	if (io_subchannel_recog(cdev, sch)) {
		spin_lock_irq(sch->lock);
		sch_set_cdev(sch, NULL);
		spin_unlock_irq(sch->lock);
		if (cdev->dev.release)
			cdev->dev.release(&cdev->dev);
		css_sch_device_unregister(sch);
	}
}


void ccw_device_move_to_orphanage(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;
	struct ccw_device *replacing_cdev;
	struct subchannel *sch;
	int ret;
	struct channel_subsystem *css;
	struct ccw_dev_id dev_id;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	sch = to_subchannel(cdev->dev.parent);
	css = to_css(sch->dev.parent);
	dev_id.devno = sch->schib.pmcw.dev;
	dev_id.ssid = sch->schid.ssid;

	/*
	 * Move the orphaned ccw device to the orphanage so the replacing
	 * ccw device can take its place on the subchannel.
	 */
	ret = device_move(&cdev->dev, &css->pseudo_subchannel->dev);
	if (ret) {
		CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to orphanage failed "
			      "(ret=%d)!\n", cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno, ret);
		return;
	}
	cdev->ccwlock = css->pseudo_subchannel->lock;
	/*
	 * Search for the replacing ccw device
	 * - among the disconnected devices
	 * - in the orphanage
	 */
	replacing_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
	if (replacing_cdev) {
		sch_attach_disconnected_device(sch, replacing_cdev);
		return;
	}
	replacing_cdev = get_orphaned_ccwdev_by_dev_id(css, &dev_id);
	if (replacing_cdev) {
		sch_attach_orphaned_device(sch, replacing_cdev);
		return;
	}
	sch_create_and_recog_new_device(sch);
}

/*
 * Register recognized device.
 */
static void
io_subchannel_register(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;
	struct subchannel *sch;
	int ret;
	unsigned long flags;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	sch = to_subchannel(cdev->dev.parent);
	css_update_ssd_info(sch);
	/*
	 * io_subchannel_register() will also be called after device
	 * recognition has been done for a boxed device (which will already
	 * be registered). We need to reprobe since we may now have sense id
	 * information.
	 */
	if (klist_node_attached(&cdev->dev.knode_parent)) {
		if (!cdev->drv) {
			ret = device_reprobe(&cdev->dev);
			if (ret)
				/* We can't do much here. */
				CIO_MSG_EVENT(0, "device_reprobe() returned"
					      " %d for 0.%x.%04x\n", ret,
					      cdev->private->dev_id.ssid,
					      cdev->private->dev_id.devno);
		}
		goto out;
	}
	/*
	 * Now we know this subchannel will stay, we can throw
	 * our delayed uevent.
	 */
	sch->dev.uevent_suppress = 0;
	kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
	/* make it known to the system */
	ret = ccw_device_register(cdev);
	if (ret) {
		CIO_MSG_EVENT(0, "Could not register ccw dev 0.%x.%04x: %d\n",
			      cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno, ret);
		put_device(&cdev->dev);
		spin_lock_irqsave(sch->lock, flags);
		sch_set_cdev(sch, NULL);
		spin_unlock_irqrestore(sch->lock, flags);
		kfree (cdev->private);
		kfree (cdev);
		put_device(&sch->dev);
		if (atomic_dec_and_test(&ccw_device_init_count))
			wake_up(&ccw_device_init_wq);
		return;
	}
	put_device(&cdev->dev);
out:
	cdev->private->flags.recog_done = 1;
	put_device(&sch->dev);
	wake_up(&cdev->private->wait_q);
	if (atomic_dec_and_test(&ccw_device_init_count))
		wake_up(&ccw_device_init_wq);
}

static void ccw_device_call_sch_unregister(struct work_struct *work)
{
	struct ccw_device_private *priv;
	struct ccw_device *cdev;
	struct subchannel *sch;

	priv = container_of(work, struct ccw_device_private, kick_work);
	cdev = priv->cdev;
	/* Get subchannel reference for local processing. */
	if (!get_device(cdev->dev.parent))
		return;
	sch = to_subchannel(cdev->dev.parent);
	css_sch_device_unregister(sch);
	/* Reset intparm to zeroes. */
	sch->schib.pmcw.intparm = 0;
	cio_modify(sch);
	/* Release cdev reference for workqueue processing.*/
	put_device(&cdev->dev);
	/* Release subchannel reference for local processing. */
	put_device(&sch->dev);
}

/*
 * subchannel recognition done. Called from the state machine.
 */
void
io_subchannel_recog_done(struct ccw_device *cdev)
{
	struct subchannel *sch;

	if (css_init_done == 0) {
		cdev->private->flags.recog_done = 1;
		return;
	}
	switch (cdev->private->state) {
	case DEV_STATE_NOT_OPER:
		cdev->private->flags.recog_done = 1;
		/* Remove device found not operational. */
		if (!get_device(&cdev->dev))
			break;
		sch = to_subchannel(cdev->dev.parent);
		PREPARE_WORK(&cdev->private->kick_work,
			     ccw_device_call_sch_unregister);
		queue_work(slow_path_wq, &cdev->private->kick_work);
		/* Release subchannel reference for asynchronous recognition. */
		put_device(&sch->dev);
		if (atomic_dec_and_test(&ccw_device_init_count))
			wake_up(&ccw_device_init_wq);
		break;
	case DEV_STATE_BOXED:
		/* Device did not respond in time. */
	case DEV_STATE_OFFLINE:
		/* 
		 * We can't register the device in interrupt context so
		 * we schedule a work item.
		 */
		if (!get_device(&cdev->dev))
			break;
		PREPARE_WORK(&cdev->private->kick_work,
			     io_subchannel_register);
		queue_work(slow_path_wq, &cdev->private->kick_work);
		break;
	}
}

static int
io_subchannel_recog(struct ccw_device *cdev, struct subchannel *sch)
{
	int rc;
	struct ccw_device_private *priv;

	sch_set_cdev(sch, cdev);
	cdev->ccwlock = sch->lock;

	/* Init private data. */
	priv = cdev->private;
	priv->dev_id.devno = sch->schib.pmcw.dev;
	priv->dev_id.ssid = sch->schid.ssid;
	priv->schid = sch->schid;
	priv->state = DEV_STATE_NOT_OPER;
	INIT_LIST_HEAD(&priv->cmb_list);
	init_waitqueue_head(&priv->wait_q);
	init_timer(&priv->timer);

	/* Set an initial name for the device. */
	snprintf (cdev->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x",
		  sch->schid.ssid, sch->schib.pmcw.dev);

	/* Increase counter of devices currently in recognition. */
	atomic_inc(&ccw_device_init_count);

	/* Start async. device sensing. */
	spin_lock_irq(sch->lock);
	rc = ccw_device_recognition(cdev);
	spin_unlock_irq(sch->lock);
	if (rc) {
		if (atomic_dec_and_test(&ccw_device_init_count))
			wake_up(&ccw_device_init_wq);
	}
	return rc;
}

static void ccw_device_move_to_sch(struct work_struct *work)
{
	struct ccw_device_private *priv;
	int rc;
	struct subchannel *sch;
	struct ccw_device *cdev;
	struct subchannel *former_parent;

	priv = container_of(work, struct ccw_device_private, kick_work);
	sch = priv->sch;
	cdev = priv->cdev;
	former_parent = ccw_device_is_orphan(cdev) ?
		NULL : to_subchannel(get_device(cdev->dev.parent));
	mutex_lock(&sch->reg_mutex);
	/* Try to move the ccw device to its new subchannel. */
	rc = device_move(&cdev->dev, &sch->dev);
	mutex_unlock(&sch->reg_mutex);
	if (rc) {
		CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to subchannel "
			      "0.%x.%04x failed (ret=%d)!\n",
			      cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno, sch->schid.ssid,
			      sch->schid.sch_no, rc);
		css_sch_device_unregister(sch);
		goto out;
	}
	if (former_parent) {
		spin_lock_irq(former_parent->lock);
		sch_set_cdev(former_parent, NULL);
		spin_unlock_irq(former_parent->lock);
		css_sch_device_unregister(former_parent);
		/* Reset intparm to zeroes. */
		former_parent->schib.pmcw.intparm = 0;
		cio_modify(former_parent);
	}
	sch_attach_device(sch, cdev);
out:
	if (former_parent)
		put_device(&former_parent->dev);
	put_device(&cdev->dev);
}

static void io_subchannel_irq(struct subchannel *sch)
{
	struct ccw_device *cdev;

	cdev = sch_get_cdev(sch);

	CIO_TRACE_EVENT(3, "IRQ");
	CIO_TRACE_EVENT(3, dev_name(&sch->dev));
	if (cdev)
		dev_fsm_event(cdev, DEV_EVENT_INTERRUPT);
}

static void io_subchannel_init_fields(struct subchannel *sch)
{
	if (cio_is_console(sch->schid))
		sch->opm = 0xff;
	else
		sch->opm = chp_get_sch_opm(sch);
	sch->lpm = sch->schib.pmcw.pam & sch->opm;
	sch->isc = cio_is_console(sch->schid) ? CONSOLE_ISC : IO_SCH_ISC;

	CIO_MSG_EVENT(6, "Detected device %04x on subchannel 0.%x.%04X"
		      " - PIM = %02X, PAM = %02X, POM = %02X\n",
		      sch->schib.pmcw.dev, sch->schid.ssid,
		      sch->schid.sch_no, sch->schib.pmcw.pim,
		      sch->schib.pmcw.pam, sch->schib.pmcw.pom);
	/* Initially set up some fields in the pmcw. */
	sch->schib.pmcw.ena = 0;
	sch->schib.pmcw.csense = 1;	/* concurrent sense */
	if ((sch->lpm & (sch->lpm - 1)) != 0)
		sch->schib.pmcw.mp = 1; /* multipath mode */
	/* clean up possible residual cmf stuff */
	sch->schib.pmcw.mme = 0;
	sch->schib.pmcw.mbfc = 0;
	sch->schib.pmcw.mbi = 0;
	sch->schib.mba = 0;
}

static int io_subchannel_probe(struct subchannel *sch)
{
	struct ccw_device *cdev;
	int rc;
	unsigned long flags;
	struct ccw_dev_id dev_id;

	cdev = sch_get_cdev(sch);
	if (cdev) {
		rc = sysfs_create_group(&sch->dev.kobj,
					&io_subchannel_attr_group);
		if (rc)
			CIO_MSG_EVENT(0, "Failed to create io subchannel "
				      "attributes for subchannel "
				      "0.%x.%04x (rc=%d)\n",
				      sch->schid.ssid, sch->schid.sch_no, rc);
		/*
		 * This subchannel already has an associated ccw_device.
		 * Throw the delayed uevent for the subchannel, register
		 * the ccw_device and exit. This happens for all early
		 * devices, e.g. the console.
		 */
		sch->dev.uevent_suppress = 0;
		kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
		cdev->dev.groups = ccwdev_attr_groups;
		device_initialize(&cdev->dev);
		ccw_device_register(cdev);
		/*
		 * Check if the device is already online. If it is
		 * the reference count needs to be corrected
		 * (see ccw_device_online and css_init_done for the
		 * ugly details).
		 */
		if (cdev->private->state != DEV_STATE_NOT_OPER &&
		    cdev->private->state != DEV_STATE_OFFLINE &&
		    cdev->private->state != DEV_STATE_BOXED)
			get_device(&cdev->dev);
		return 0;
	}
	io_subchannel_init_fields(sch);
	/*
	 * First check if a fitting device may be found amongst the
	 * disconnected devices or in the orphanage.
	 */
	dev_id.devno = sch->schib.pmcw.dev;
	dev_id.ssid = sch->schid.ssid;
	rc = sysfs_create_group(&sch->dev.kobj,
				&io_subchannel_attr_group);
	if (rc)
		return rc;
	/* Allocate I/O subchannel private data. */
	sch->private = kzalloc(sizeof(struct io_subchannel_private),
			       GFP_KERNEL | GFP_DMA);
	if (!sch->private) {
		rc = -ENOMEM;
		goto out_err;
	}
	cdev = get_disc_ccwdev_by_dev_id(&dev_id, NULL);
	if (!cdev)
		cdev = get_orphaned_ccwdev_by_dev_id(to_css(sch->dev.parent),
						     &dev_id);
	if (cdev) {
		/*
		 * Schedule moving the device until when we have a registered
		 * subchannel to move to and succeed the probe. We can
		 * unregister later again, when the probe is through.
		 */
		cdev->private->sch = sch;
		PREPARE_WORK(&cdev->private->kick_work,
			     ccw_device_move_to_sch);
		queue_work(slow_path_wq, &cdev->private->kick_work);
		return 0;
	}
	cdev = io_subchannel_create_ccwdev(sch);
	if (IS_ERR(cdev)) {
		rc = PTR_ERR(cdev);
		goto out_err;
	}
	rc = io_subchannel_recog(cdev, sch);
	if (rc) {
		spin_lock_irqsave(sch->lock, flags);
		sch_set_cdev(sch, NULL);
		spin_unlock_irqrestore(sch->lock, flags);
		if (cdev->dev.release)
			cdev->dev.release(&cdev->dev);
		goto out_err;
	}
	return 0;
out_err:
	kfree(sch->private);
	sysfs_remove_group(&sch->dev.kobj, &io_subchannel_attr_group);
	return rc;
}

static int
io_subchannel_remove (struct subchannel *sch)
{
	struct ccw_device *cdev;
	unsigned long flags;

	cdev = sch_get_cdev(sch);
	if (!cdev)
		return 0;
	/* Set ccw device to not operational and drop reference. */
	spin_lock_irqsave(cdev->ccwlock, flags);
	sch_set_cdev(sch, NULL);
	cdev->private->state = DEV_STATE_NOT_OPER;
	spin_unlock_irqrestore(cdev->ccwlock, flags);
	ccw_device_unregister(cdev);
	put_device(&cdev->dev);
	kfree(sch->private);
	sysfs_remove_group(&sch->dev.kobj, &io_subchannel_attr_group);
	return 0;
}

static int io_subchannel_notify(struct subchannel *sch, int event)
{
	struct ccw_device *cdev;

	cdev = sch_get_cdev(sch);
	if (!cdev)
		return 0;
	return ccw_device_notify(cdev, event);
}

static void io_subchannel_verify(struct subchannel *sch)
{
	struct ccw_device *cdev;

	cdev = sch_get_cdev(sch);
	if (cdev)
		dev_fsm_event(cdev, DEV_EVENT_VERIFY);
}

static int check_for_io_on_path(struct subchannel *sch, int mask)
{
	int cc;

	cc = stsch(sch->schid, &sch->schib);
	if (cc)
		return 0;
	if (scsw_actl(&sch->schib.scsw) && sch->schib.pmcw.lpum == mask)
		return 1;
	return 0;
}

static void terminate_internal_io(struct subchannel *sch,
				  struct ccw_device *cdev)
{
	if (cio_clear(sch)) {
		/* Recheck device in case clear failed. */
		sch->lpm = 0;
		if (cdev->online)
			dev_fsm_event(cdev, DEV_EVENT_VERIFY);
		else
			css_schedule_eval(sch->schid);
		return;
	}
	cdev->private->state = DEV_STATE_CLEAR_VERIFY;
	/* Request retry of internal operation. */
	cdev->private->flags.intretry = 1;
	/* Call handler. */
	if (cdev->handler)
		cdev->handler(cdev, cdev->private->intparm,
			      ERR_PTR(-EIO));
}

static void io_subchannel_terminate_path(struct subchannel *sch, u8 mask)
{
	struct ccw_device *cdev;

	cdev = sch_get_cdev(sch);
	if (!cdev)
		return;
	if (check_for_io_on_path(sch, mask)) {
		if (cdev->private->state == DEV_STATE_ONLINE)
			ccw_device_kill_io(cdev);
		else {
			terminate_internal_io(sch, cdev);
			/* Re-start path verification. */
			dev_fsm_event(cdev, DEV_EVENT_VERIFY);
		}
	} else
		/* trigger path verification. */
		dev_fsm_event(cdev, DEV_EVENT_VERIFY);

}

static int io_subchannel_chp_event(struct subchannel *sch,
				   struct chp_link *link, int event)
{
	int mask;

	mask = chp_ssd_get_mask(&sch->ssd_info, link);
	if (!mask)
		return 0;
	switch (event) {
	case CHP_VARY_OFF:
		sch->opm &= ~mask;
		sch->lpm &= ~mask;
		io_subchannel_terminate_path(sch, mask);
		break;
	case CHP_VARY_ON:
		sch->opm |= mask;
		sch->lpm |= mask;
		io_subchannel_verify(sch);
		break;
	case CHP_OFFLINE:
		if (stsch(sch->schid, &sch->schib))
			return -ENXIO;
		if (!css_sch_is_valid(&sch->schib))
			return -ENODEV;
		io_subchannel_terminate_path(sch, mask);
		break;
	case CHP_ONLINE:
		if (stsch(sch->schid, &sch->schib))
			return -ENXIO;
		sch->lpm |= mask & sch->opm;
		io_subchannel_verify(sch);
		break;
	}
	return 0;
}

static void
io_subchannel_shutdown(struct subchannel *sch)
{
	struct ccw_device *cdev;
	int ret;

	cdev = sch_get_cdev(sch);

	if (cio_is_console(sch->schid))
		return;
	if (!sch->schib.pmcw.ena)
		/* Nothing to do. */
		return;
	ret = cio_disable_subchannel(sch);
	if (ret != -EBUSY)
		/* Subchannel is disabled, we're done. */
		return;
	cdev->private->state = DEV_STATE_QUIESCE;
	if (cdev->handler)
		cdev->handler(cdev, cdev->private->intparm,
			      ERR_PTR(-EIO));
	ret = ccw_device_cancel_halt_clear(cdev);
	if (ret == -EBUSY) {
		ccw_device_set_timeout(cdev, HZ/10);
		wait_event(cdev->private->wait_q, dev_fsm_final_state(cdev));
	}
	cio_disable_subchannel(sch);
}

static int io_subchannel_get_status(struct subchannel *sch)
{
	struct schib schib;

	if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
		return CIO_GONE;
	if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
		return CIO_REVALIDATE;
	if (!sch->lpm)
		return CIO_NO_PATH;
	return CIO_OPER;
}

static int device_is_disconnected(struct ccw_device *cdev)
{
	if (!cdev)
		return 0;
	return (cdev->private->state == DEV_STATE_DISCONNECTED ||
		cdev->private->state == DEV_STATE_DISCONNECTED_SENSE_ID);
}

static int recovery_check(struct device *dev, void *data)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	int *redo = data;

	spin_lock_irq(cdev->ccwlock);
	switch (cdev->private->state) {
	case DEV_STATE_DISCONNECTED:
		CIO_MSG_EVENT(3, "recovery: trigger 0.%x.%04x\n",
			      cdev->private->dev_id.ssid,
			      cdev->private->dev_id.devno);
		dev_fsm_event(cdev, DEV_EVENT_VERIFY);
		*redo = 1;
		break;
	case DEV_STATE_DISCONNECTED_SENSE_ID:
		*redo = 1;
		break;
	}
	spin_unlock_irq(cdev->ccwlock);

	return 0;
}

static void recovery_work_func(struct work_struct *unused)
{
	int redo = 0;

	bus_for_each_dev(&ccw_bus_type, NULL, &redo, recovery_check);
	if (redo) {
		spin_lock_irq(&recovery_lock);
		if (!timer_pending(&recovery_timer)) {
			if (recovery_phase < ARRAY_SIZE(recovery_delay) - 1)
				recovery_phase++;
			mod_timer(&recovery_timer, jiffies +
				  recovery_delay[recovery_phase] * HZ);
		}
		spin_unlock_irq(&recovery_lock);
	} else
		CIO_MSG_EVENT(4, "recovery: end\n");
}

static DECLARE_WORK(recovery_work, recovery_work_func);

static void recovery_func(unsigned long data)
{
	/*
	 * We can't do our recovery in softirq context and it's not
	 * performance critical, so we schedule it.
	 */
	schedule_work(&recovery_work);
}

static void ccw_device_schedule_recovery(void)
{
	unsigned long flags;

	CIO_MSG_EVENT(4, "recovery: schedule\n");
	spin_lock_irqsave(&recovery_lock, flags);
	if (!timer_pending(&recovery_timer) || (recovery_phase != 0)) {
		recovery_phase = 0;
		mod_timer(&recovery_timer, jiffies + recovery_delay[0] * HZ);
	}
	spin_unlock_irqrestore(&recovery_lock, flags);
}

static int purge_fn(struct device *dev, void *data)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_device_private *priv = cdev->private;
	int unreg;

	spin_lock_irq(cdev->ccwlock);
	unreg = is_blacklisted(priv->dev_id.ssid, priv->dev_id.devno) &&
		(priv->state == DEV_STATE_OFFLINE);
	spin_unlock_irq(cdev->ccwlock);
	if (!unreg)
		goto out;
	if (!get_device(&cdev->dev))
		goto out;
	CIO_MSG_EVENT(3, "ccw: purging 0.%x.%04x\n", priv->dev_id.ssid,
		      priv->dev_id.devno);
	PREPARE_WORK(&cdev->private->kick_work, ccw_device_call_sch_unregister);
	queue_work(slow_path_wq, &cdev->private->kick_work);

out:
	/* Abort loop in case of pending signal. */
	if (signal_pending(current))
		return -EINTR;

	return 0;
}

/**
 * ccw_purge_blacklisted - purge unused, blacklisted devices
 *
 * Unregister all ccw devices that are offline and on the blacklist.
 */
int ccw_purge_blacklisted(void)
{
	CIO_MSG_EVENT(2, "ccw: purging blacklisted devices\n");
	bus_for_each_dev(&ccw_bus_type, NULL, NULL, purge_fn);
	return 0;
}

static void device_set_disconnected(struct ccw_device *cdev)
{
	if (!cdev)
		return;
	ccw_device_set_timeout(cdev, 0);
	cdev->private->flags.fake_irb = 0;
	cdev->private->state = DEV_STATE_DISCONNECTED;
	if (cdev->online)
		ccw_device_schedule_recovery();
}

void ccw_device_set_notoper(struct ccw_device *cdev)
{
	struct subchannel *sch = to_subchannel(cdev->dev.parent);

	CIO_TRACE_EVENT(2, "notoper");
	CIO_TRACE_EVENT(2, sch->dev.bus_id);
	ccw_device_set_timeout(cdev, 0);
	cio_disable_subchannel(sch);
	cdev->private->state = DEV_STATE_NOT_OPER;
}

static int io_subchannel_sch_event(struct subchannel *sch, int slow)
{
	int event, ret, disc;
	unsigned long flags;
	enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE, DISC } action;
	struct ccw_device *cdev;

	spin_lock_irqsave(sch->lock, flags);
	cdev = sch_get_cdev(sch);
	disc = device_is_disconnected(cdev);
	if (disc && slow) {
		/* Disconnected devices are evaluated directly only.*/
		spin_unlock_irqrestore(sch->lock, flags);
		return 0;
	}
	/* No interrupt after machine check - kill pending timers. */
	if (cdev)
		ccw_device_set_timeout(cdev, 0);
	if (!disc && !slow) {
		/* Non-disconnected devices are evaluated on the slow path. */
		spin_unlock_irqrestore(sch->lock, flags);
		return -EAGAIN;
	}
	event = io_subchannel_get_status(sch);
	CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
		      sch->schid.ssid, sch->schid.sch_no, event,
		      disc ? "disconnected" : "normal",
		      slow ? "slow" : "fast");
	/* Analyze subchannel status. */
	action = NONE;
	switch (event) {
	case CIO_NO_PATH:
		if (disc) {
			/* Check if paths have become available. */
			action = REPROBE;
			break;
		}
		/* fall through */
	case CIO_GONE:
		/* Ask driver what to do with device. */
		if (io_subchannel_notify(sch, event))
			action = DISC;
		else
			action = UNREGISTER;
		break;
	case CIO_REVALIDATE:
		/* Device will be removed, so no notify necessary. */
		if (disc)
			/* Reprobe because immediate unregister might block. */
			action = REPROBE;
		else
			action = UNREGISTER_PROBE;
		break;
	case CIO_OPER:
		if (disc)
			/* Get device operational again. */
			action = REPROBE;
		break;
	}
	/* Perform action. */
	ret = 0;
	switch (action) {
	case UNREGISTER:
	case UNREGISTER_PROBE:
		ccw_device_set_notoper(cdev);
		/* Unregister device (will use subchannel lock). */
		spin_unlock_irqrestore(sch->lock, flags);
		css_sch_device_unregister(sch);
		spin_lock_irqsave(sch->lock, flags);

		/* Reset intparm to zeroes. */
		sch->schib.pmcw.intparm = 0;
		cio_modify(sch);
		break;
	case REPROBE:
		ccw_device_trigger_reprobe(cdev);
		break;
	case DISC:
		device_set_disconnected(cdev);
		break;
	default:
		break;
	}
	spin_unlock_irqrestore(sch->lock, flags);
	/* Probe if necessary. */
	if (action == UNREGISTER_PROBE)
		ret = css_probe_device(sch->schid);

	return ret;
}

#ifdef CONFIG_CCW_CONSOLE
static struct ccw_device console_cdev;
static struct ccw_device_private console_private;
static int console_cdev_in_use;

static DEFINE_SPINLOCK(ccw_console_lock);

spinlock_t * cio_get_console_lock(void)
{
	return &ccw_console_lock;
}

static int ccw_device_console_enable(struct ccw_device *cdev,
				     struct subchannel *sch)
{
	int rc;

	/* Attach subchannel private data. */
	sch->private = cio_get_console_priv();
	memset(sch->private, 0, sizeof(struct io_subchannel_private));
	io_subchannel_init_fields(sch);
	sch->driver = &io_subchannel_driver;
	/* Initialize the ccw_device structure. */
	cdev->dev.parent= &sch->dev;
	rc = io_subchannel_recog(cdev, sch);
	if (rc)
		return rc;

	/* Now wait for the async. recognition to come to an end. */
	spin_lock_irq(cdev->ccwlock);
	while (!dev_fsm_final_state(cdev))
		wait_cons_dev();
	rc = -EIO;
	if (cdev->private->state != DEV_STATE_OFFLINE)
		goto out_unlock;
	ccw_device_online(cdev);
	while (!dev_fsm_final_state(cdev))
		wait_cons_dev();
	if (cdev->private->state != DEV_STATE_ONLINE)
		goto out_unlock;
	rc = 0;
out_unlock:
	spin_unlock_irq(cdev->ccwlock);
	return 0;
}

struct ccw_device *
ccw_device_probe_console(void)
{
	struct subchannel *sch;
	int ret;

	if (xchg(&console_cdev_in_use, 1) != 0)
		return ERR_PTR(-EBUSY);
	sch = cio_probe_console();
	if (IS_ERR(sch)) {
		console_cdev_in_use = 0;
		return (void *) sch;
	}
	memset(&console_cdev, 0, sizeof(struct ccw_device));
	memset(&console_private, 0, sizeof(struct ccw_device_private));
	console_cdev.private = &console_private;
	console_private.cdev = &console_cdev;
	ret = ccw_device_console_enable(&console_cdev, sch);
	if (ret) {
		cio_release_console();
		console_cdev_in_use = 0;
		return ERR_PTR(ret);
	}
	console_cdev.online = 1;
	return &console_cdev;
}
#endif

/*
 * get ccw_device matching the busid, but only if owned by cdrv
 */
static int
__ccwdev_check_busid(struct device *dev, void *id)
{
	char *bus_id;

	bus_id = id;

	return (strncmp(bus_id, dev_name(dev), BUS_ID_SIZE) == 0);
}


/**
 * get_ccwdev_by_busid() - obtain device from a bus id
 * @cdrv: driver the device is owned by
 * @bus_id: bus id of the device to be searched
 *
 * This function searches all devices owned by @cdrv for a device with a bus
 * id matching @bus_id.
 * Returns:
 *  If a match is found, its reference count of the found device is increased
 *  and it is returned; else %NULL is returned.
 */
struct ccw_device *get_ccwdev_by_busid(struct ccw_driver *cdrv,
				       const char *bus_id)
{
	struct device *dev;
	struct device_driver *drv;

	drv = get_driver(&cdrv->driver);
	if (!drv)
		return NULL;

	dev = driver_find_device(drv, NULL, (void *)bus_id,
				 __ccwdev_check_busid);
	put_driver(drv);

	return dev ? to_ccwdev(dev) : NULL;
}

/************************** device driver handling ************************/

/* This is the implementation of the ccw_driver class. The probe, remove
 * and release methods are initially very similar to the device_driver
 * implementations, with the difference that they have ccw_device
 * arguments.
 *
 * A ccw driver also contains the information that is needed for
 * device matching.
 */
static int
ccw_device_probe (struct device *dev)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_driver *cdrv = to_ccwdrv(dev->driver);
	int ret;

	cdev->drv = cdrv; /* to let the driver call _set_online */

	ret = cdrv->probe ? cdrv->probe(cdev) : -ENODEV;

	if (ret) {
		cdev->drv = NULL;
		return ret;
	}

	return 0;
}

static int
ccw_device_remove (struct device *dev)
{
	struct ccw_device *cdev = to_ccwdev(dev);
	struct ccw_driver *cdrv = cdev->drv;
	int ret;

	if (cdrv->remove)
		cdrv->remove(cdev);
	if (cdev->online) {
		cdev->online = 0;
		spin_lock_irq(cdev->ccwlock);
		ret = ccw_device_offline(cdev);
		spin_unlock_irq(cdev->ccwlock);
		if (ret == 0)
			wait_event(cdev->private->wait_q,
				   dev_fsm_final_state(cdev));
		else
			CIO_MSG_EVENT(0, "ccw_device_offline returned %d, "
				      "device 0.%x.%04x\n",
				      ret, cdev->private->dev_id.ssid,
				      cdev->private->dev_id.devno);
	}
	ccw_device_set_timeout(cdev, 0);
	cdev->drv = NULL;
	return 0;
}

static void ccw_device_shutdown(struct device *dev)
{
	struct ccw_device *cdev;

	cdev = to_ccwdev(dev);
	if (cdev->drv && cdev->drv->shutdown)
		cdev->drv->shutdown(cdev);
	disable_cmf(cdev);
}

struct bus_type ccw_bus_type = {
	.name   = "ccw",
	.match  = ccw_bus_match,
	.uevent = ccw_uevent,
	.probe  = ccw_device_probe,
	.remove = ccw_device_remove,
	.shutdown = ccw_device_shutdown,
};

/**
 * ccw_driver_register() - register a ccw driver
 * @cdriver: driver to be registered
 *
 * This function is mainly a wrapper around driver_register().
 * Returns:
 *   %0 on success and a negative error value on failure.
 */
int ccw_driver_register(struct ccw_driver *cdriver)
{
	struct device_driver *drv = &cdriver->driver;

	drv->bus = &ccw_bus_type;
	drv->name = cdriver->name;
	drv->owner = cdriver->owner;

	return driver_register(drv);
}

/**
 * ccw_driver_unregister() - deregister a ccw driver
 * @cdriver: driver to be deregistered
 *
 * This function is mainly a wrapper around driver_unregister().
 */
void ccw_driver_unregister(struct ccw_driver *cdriver)
{
	driver_unregister(&cdriver->driver);
}

/* Helper func for qdio. */
struct subchannel_id
ccw_device_get_subchannel_id(struct ccw_device *cdev)
{
	struct subchannel *sch;

	sch = to_subchannel(cdev->dev.parent);
	return sch->schid;
}

MODULE_LICENSE("GPL");
EXPORT_SYMBOL(ccw_device_set_online);
EXPORT_SYMBOL(ccw_device_set_offline);
EXPORT_SYMBOL(ccw_driver_register);
EXPORT_SYMBOL(ccw_driver_unregister);
EXPORT_SYMBOL(get_ccwdev_by_busid);
EXPORT_SYMBOL(ccw_bus_type);
EXPORT_SYMBOL(ccw_device_work);
EXPORT_SYMBOL_GPL(ccw_device_get_subchannel_id);