summaryrefslogtreecommitdiff
path: root/drivers/usb/gadget/inode.c
blob: 5c40980a5bd94f263e3f7618dff22a96896fa9c1 (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
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
/*
 * inode.c -- user mode filesystem api for usb gadget controllers
 *
 * Copyright (C) 2003-2004 David Brownell
 * Copyright (C) 2003 Agilent Technologies
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


// #define	DEBUG 			/* data to help fault diagnosis */
// #define	VERBOSE		/* extra debug messages (success too) */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/uts.h>
#include <linux/wait.h>
#include <linux/compiler.h>
#include <asm/uaccess.h>
#include <linux/slab.h>

#include <linux/device.h>
#include <linux/moduleparam.h>

#include <linux/usb_gadgetfs.h>
#include <linux/usb_gadget.h>


/*
 * The gadgetfs API maps each endpoint to a file descriptor so that you
 * can use standard synchronous read/write calls for I/O.  There's some
 * O_NONBLOCK and O_ASYNC/FASYNC style i/o support.  Example usermode
 * drivers show how this works in practice.  You can also use AIO to
 * eliminate I/O gaps between requests, to help when streaming data.
 *
 * Key parts that must be USB-specific are protocols defining how the
 * read/write operations relate to the hardware state machines.  There
 * are two types of files.  One type is for the device, implementing ep0.
 * The other type is for each IN or OUT endpoint.  In both cases, the
 * user mode driver must configure the hardware before using it.
 *
 * - First, dev_config() is called when /dev/gadget/$CHIP is configured
 *   (by writing configuration and device descriptors).  Afterwards it
 *   may serve as a source of device events, used to handle all control
 *   requests other than basic enumeration.
 *
 * - Then either immediately, or after a SET_CONFIGURATION control request,
 *   ep_config() is called when each /dev/gadget/ep* file is configured
 *   (by writing endpoint descriptors).  Afterwards these files are used
 *   to write() IN data or to read() OUT data.  To halt the endpoint, a
 *   "wrong direction" request is issued (like reading an IN endpoint).
 *
 * Unlike "usbfs" the only ioctl()s are for things that are rare, and maybe
 * not possible on all hardware.  For example, precise fault handling with
 * respect to data left in endpoint fifos after aborted operations; or
 * selective clearing of endpoint halts, to implement SET_INTERFACE.
 */

#define	DRIVER_DESC	"USB Gadget filesystem"
#define	DRIVER_VERSION	"24 Aug 2004"

static const char driver_desc [] = DRIVER_DESC;
static const char shortname [] = "gadgetfs";

MODULE_DESCRIPTION (DRIVER_DESC);
MODULE_AUTHOR ("David Brownell");
MODULE_LICENSE ("GPL");


/*----------------------------------------------------------------------*/

#define GADGETFS_MAGIC		0xaee71ee7
#define DMA_ADDR_INVALID	(~(dma_addr_t)0)

/* /dev/gadget/$CHIP represents ep0 and the whole device */
enum ep0_state {
	/* DISBLED is the initial state.
	 */
	STATE_DEV_DISABLED = 0,

	/* Only one open() of /dev/gadget/$CHIP; only one file tracks
	 * ep0/device i/o modes and binding to the controller.  Driver
	 * must always write descriptors to initialize the device, then
	 * the device becomes UNCONNECTED until enumeration.
	 */
	STATE_OPENED,

	/* From then on, ep0 fd is in either of two basic modes:
	 * - (UN)CONNECTED: read usb_gadgetfs_event(s) from it
	 * - SETUP: read/write will transfer control data and succeed;
	 *   or if "wrong direction", performs protocol stall
	 */
	STATE_UNCONNECTED,
	STATE_CONNECTED,
	STATE_SETUP,

	/* UNBOUND means the driver closed ep0, so the device won't be
	 * accessible again (DEV_DISABLED) until all fds are closed.
	 */
	STATE_DEV_UNBOUND,
};

/* enough for the whole queue: most events invalidate others */
#define	N_EVENT			5

struct dev_data {
	spinlock_t			lock;
	atomic_t			count;
	enum ep0_state			state;
	struct usb_gadgetfs_event	event [N_EVENT];
	unsigned			ev_next;
	struct fasync_struct		*fasync;
	u8				current_config;

	/* drivers reading ep0 MUST handle control requests (SETUP)
	 * reported that way; else the host will time out.
	 */
	unsigned			usermode_setup : 1,
					setup_in : 1,
					setup_can_stall : 1,
					setup_out_ready : 1,
					setup_out_error : 1,
					setup_abort : 1;

	/* the rest is basically write-once */
	struct usb_config_descriptor	*config, *hs_config;
	struct usb_device_descriptor	*dev;
	struct usb_request		*req;
	struct usb_gadget		*gadget;
	struct list_head		epfiles;
	void				*buf;
	wait_queue_head_t		wait;
	struct super_block		*sb;
	struct dentry			*dentry;

	/* except this scratch i/o buffer for ep0 */
	u8				rbuf [256];
};

static inline void get_dev (struct dev_data *data)
{
	atomic_inc (&data->count);
}

static void put_dev (struct dev_data *data)
{
	if (likely (!atomic_dec_and_test (&data->count)))
		return;
	/* needs no more cleanup */
	BUG_ON (waitqueue_active (&data->wait));
	kfree (data);
}

static struct dev_data *dev_new (void)
{
	struct dev_data		*dev;

	dev = kmalloc (sizeof *dev, GFP_KERNEL);
	if (!dev)
		return NULL;
	memset (dev, 0, sizeof *dev);
	dev->state = STATE_DEV_DISABLED;
	atomic_set (&dev->count, 1);
	spin_lock_init (&dev->lock);
	INIT_LIST_HEAD (&dev->epfiles);
	init_waitqueue_head (&dev->wait);
	return dev;
}

/*----------------------------------------------------------------------*/

/* other /dev/gadget/$ENDPOINT files represent endpoints */
enum ep_state {
	STATE_EP_DISABLED = 0,
	STATE_EP_READY,
	STATE_EP_DEFER_ENABLE,
	STATE_EP_ENABLED,
	STATE_EP_UNBOUND,
};

struct ep_data {
	struct semaphore		lock;
	enum ep_state			state;
	atomic_t			count;
	struct dev_data			*dev;
	/* must hold dev->lock before accessing ep or req */
	struct usb_ep			*ep;
	struct usb_request		*req;
	ssize_t				status;
	char				name [16];
	struct usb_endpoint_descriptor	desc, hs_desc;
	struct list_head		epfiles;
	wait_queue_head_t		wait;
	struct dentry			*dentry;
	struct inode			*inode;
};

static inline void get_ep (struct ep_data *data)
{
	atomic_inc (&data->count);
}

static void put_ep (struct ep_data *data)
{
	if (likely (!atomic_dec_and_test (&data->count)))
		return;
	put_dev (data->dev);
	/* needs no more cleanup */
	BUG_ON (!list_empty (&data->epfiles));
	BUG_ON (waitqueue_active (&data->wait));
	BUG_ON (down_trylock (&data->lock) != 0);
	kfree (data);
}

/*----------------------------------------------------------------------*/

/* most "how to use the hardware" policy choices are in userspace:
 * mapping endpoint roles (which the driver needs) to the capabilities
 * which the usb controller has.  most of those capabilities are exposed
 * implicitly, starting with the driver name and then endpoint names.
 */

static const char *CHIP;

/*----------------------------------------------------------------------*/

/* NOTE:  don't use dev_printk calls before binding to the gadget
 * at the end of ep0 configuration, or after unbind.
 */

/* too wordy: dev_printk(level , &(d)->gadget->dev , fmt , ## args) */
#define xprintk(d,level,fmt,args...) \
	printk(level "%s: " fmt , shortname , ## args)

#ifdef DEBUG
#define DBG(dev,fmt,args...) \
	xprintk(dev , KERN_DEBUG , fmt , ## args)
#else
#define DBG(dev,fmt,args...) \
	do { } while (0)
#endif /* DEBUG */

#ifdef VERBOSE
#define VDEBUG	DBG
#else
#define VDEBUG(dev,fmt,args...) \
	do { } while (0)
#endif /* DEBUG */

#define ERROR(dev,fmt,args...) \
	xprintk(dev , KERN_ERR , fmt , ## args)
#define WARN(dev,fmt,args...) \
	xprintk(dev , KERN_WARNING , fmt , ## args)
#define INFO(dev,fmt,args...) \
	xprintk(dev , KERN_INFO , fmt , ## args)


/*----------------------------------------------------------------------*/

/* SYNCHRONOUS ENDPOINT OPERATIONS (bulk/intr/iso)
 *
 * After opening, configure non-control endpoints.  Then use normal
 * stream read() and write() requests; and maybe ioctl() to get more
 * precise FIFO status when recovering from cancellation.
 */

static void epio_complete (struct usb_ep *ep, struct usb_request *req)
{
	struct ep_data	*epdata = ep->driver_data;

	if (!req->context)
		return;
	if (req->status)
		epdata->status = req->status;
	else
		epdata->status = req->actual;
	complete ((struct completion *)req->context);
}

/* tasklock endpoint, returning when it's connected.
 * still need dev->lock to use epdata->ep.
 */
static int
get_ready_ep (unsigned f_flags, struct ep_data *epdata)
{
	int	val;

	if (f_flags & O_NONBLOCK) {
		if (down_trylock (&epdata->lock) != 0)
			goto nonblock;
		if (epdata->state != STATE_EP_ENABLED) {
			up (&epdata->lock);
nonblock:
			val = -EAGAIN;
		} else
			val = 0;
		return val;
	}

	if ((val = down_interruptible (&epdata->lock)) < 0)
		return val;
newstate:
	switch (epdata->state) {
	case STATE_EP_ENABLED:
		break;
	case STATE_EP_DEFER_ENABLE:
		DBG (epdata->dev, "%s wait for host\n", epdata->name);
		if ((val = wait_event_interruptible (epdata->wait, 
				epdata->state != STATE_EP_DEFER_ENABLE
				|| epdata->dev->state == STATE_DEV_UNBOUND
				)) < 0)
			goto fail;
		goto newstate;
	// case STATE_EP_DISABLED:		/* "can't happen" */
	// case STATE_EP_READY:			/* "can't happen" */
	default:				/* error! */
		pr_debug ("%s: ep %p not available, state %d\n",
				shortname, epdata, epdata->state);
		// FALLTHROUGH
	case STATE_EP_UNBOUND:			/* clean disconnect */
		val = -ENODEV;
fail:
		up (&epdata->lock);
	}
	return val;
}

static ssize_t
ep_io (struct ep_data *epdata, void *buf, unsigned len)
{
	DECLARE_COMPLETION (done);
	int value;

	spin_lock_irq (&epdata->dev->lock);
	if (likely (epdata->ep != NULL)) {
		struct usb_request	*req = epdata->req;

		req->context = &done;
		req->complete = epio_complete;
		req->buf = buf;
		req->length = len;
		value = usb_ep_queue (epdata->ep, req, GFP_ATOMIC);
	} else
		value = -ENODEV;
	spin_unlock_irq (&epdata->dev->lock);

	if (likely (value == 0)) {
		value = wait_event_interruptible (done.wait, done.done);
		if (value != 0) {
			spin_lock_irq (&epdata->dev->lock);
			if (likely (epdata->ep != NULL)) {
				DBG (epdata->dev, "%s i/o interrupted\n",
						epdata->name);
				usb_ep_dequeue (epdata->ep, epdata->req);
				spin_unlock_irq (&epdata->dev->lock);

				wait_event (done.wait, done.done);
				if (epdata->status == -ECONNRESET)
					epdata->status = -EINTR;
			} else {
				spin_unlock_irq (&epdata->dev->lock);

				DBG (epdata->dev, "endpoint gone\n");
				epdata->status = -ENODEV;
			}
		}
		return epdata->status;
	}
	return value;
}


/* handle a synchronous OUT bulk/intr/iso transfer */
static ssize_t
ep_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
{
	struct ep_data		*data = fd->private_data;
	void			*kbuf;
	ssize_t			value;

	if ((value = get_ready_ep (fd->f_flags, data)) < 0)
		return value;

	/* halt any endpoint by doing a "wrong direction" i/o call */
	if (data->desc.bEndpointAddress & USB_DIR_IN) {
		if ((data->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
				== USB_ENDPOINT_XFER_ISOC)
			return -EINVAL;
		DBG (data->dev, "%s halt\n", data->name);
		spin_lock_irq (&data->dev->lock);
		if (likely (data->ep != NULL))
			usb_ep_set_halt (data->ep);
		spin_unlock_irq (&data->dev->lock);
		up (&data->lock);
		return -EBADMSG;
	}

	/* FIXME readahead for O_NONBLOCK and poll(); careful with ZLPs */

	value = -ENOMEM;
	kbuf = kmalloc (len, SLAB_KERNEL);
	if (unlikely (!kbuf))
		goto free1;

	value = ep_io (data, kbuf, len);
	VDEBUG (data->dev, "%s read %zu OUT, status %d\n",
		data->name, len, (int) value);
	if (value >= 0 && copy_to_user (buf, kbuf, value))
		value = -EFAULT;

free1:
	up (&data->lock);
	kfree (kbuf);
	return value;
}

/* handle a synchronous IN bulk/intr/iso transfer */
static ssize_t
ep_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
	struct ep_data		*data = fd->private_data;
	void			*kbuf;
	ssize_t			value;

	if ((value = get_ready_ep (fd->f_flags, data)) < 0)
		return value;

	/* halt any endpoint by doing a "wrong direction" i/o call */
	if (!(data->desc.bEndpointAddress & USB_DIR_IN)) {
		if ((data->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
				== USB_ENDPOINT_XFER_ISOC)
			return -EINVAL;
		DBG (data->dev, "%s halt\n", data->name);
		spin_lock_irq (&data->dev->lock);
		if (likely (data->ep != NULL))
			usb_ep_set_halt (data->ep);
		spin_unlock_irq (&data->dev->lock);
		up (&data->lock);
		return -EBADMSG;
	}

	/* FIXME writebehind for O_NONBLOCK and poll(), qlen = 1 */

	value = -ENOMEM;
	kbuf = kmalloc (len, SLAB_KERNEL);
	if (!kbuf)
		goto free1;
	if (copy_from_user (kbuf, buf, len)) {
		value = -EFAULT;
		goto free1;
	}

	value = ep_io (data, kbuf, len);
	VDEBUG (data->dev, "%s write %zu IN, status %d\n",
		data->name, len, (int) value);
free1:
	up (&data->lock);
	kfree (kbuf);
	return value;
}

static int
ep_release (struct inode *inode, struct file *fd)
{
	struct ep_data		*data = fd->private_data;

	/* clean up if this can be reopened */
	if (data->state != STATE_EP_UNBOUND) {
		data->state = STATE_EP_DISABLED;
		data->desc.bDescriptorType = 0;
		data->hs_desc.bDescriptorType = 0;
		usb_ep_disable(data->ep);
	}
	put_ep (data);
	return 0;
}

static int ep_ioctl (struct inode *inode, struct file *fd,
		unsigned code, unsigned long value)
{
	struct ep_data		*data = fd->private_data;
	int			status;

	if ((status = get_ready_ep (fd->f_flags, data)) < 0)
		return status;

	spin_lock_irq (&data->dev->lock);
	if (likely (data->ep != NULL)) {
		switch (code) {
		case GADGETFS_FIFO_STATUS:
			status = usb_ep_fifo_status (data->ep);
			break;
		case GADGETFS_FIFO_FLUSH:
			usb_ep_fifo_flush (data->ep);
			break;
		case GADGETFS_CLEAR_HALT:
			status = usb_ep_clear_halt (data->ep);
			break;
		default:
			status = -ENOTTY;
		}
	} else
		status = -ENODEV;
	spin_unlock_irq (&data->dev->lock);
	up (&data->lock);
	return status;
}

/*----------------------------------------------------------------------*/

/* ASYNCHRONOUS ENDPOINT I/O OPERATIONS (bulk/intr/iso) */

struct kiocb_priv {
	struct usb_request	*req;
	struct ep_data		*epdata;
	void			*buf;
	char __user		*ubuf;
	unsigned		actual;
};

static int ep_aio_cancel(struct kiocb *iocb, struct io_event *e)
{
	struct kiocb_priv	*priv = iocb->private;
	struct ep_data		*epdata;
	int			value;

	local_irq_disable();
	epdata = priv->epdata;
	// spin_lock(&epdata->dev->lock);
	kiocbSetCancelled(iocb);
	if (likely(epdata && epdata->ep && priv->req))
		value = usb_ep_dequeue (epdata->ep, priv->req);
	else
		value = -EINVAL;
	// spin_unlock(&epdata->dev->lock);
	local_irq_enable();

	aio_put_req(iocb);
	return value;
}

static ssize_t ep_aio_read_retry(struct kiocb *iocb)
{
	struct kiocb_priv	*priv = iocb->private;
	ssize_t			status = priv->actual;

	/* we "retry" to get the right mm context for this: */
	status = copy_to_user(priv->ubuf, priv->buf, priv->actual);
	if (unlikely(0 != status))
		status = -EFAULT;
	else
		status = priv->actual;
	kfree(priv->buf);
	kfree(priv);
	aio_put_req(iocb);
	return status;
}

static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct kiocb		*iocb = req->context;
	struct kiocb_priv	*priv = iocb->private;
	struct ep_data		*epdata = priv->epdata;

	/* lock against disconnect (and ideally, cancel) */
	spin_lock(&epdata->dev->lock);
	priv->req = NULL;
	priv->epdata = NULL;
	if (NULL == iocb->ki_retry
			|| unlikely(0 == req->actual)
			|| unlikely(kiocbIsCancelled(iocb))) {
		kfree(req->buf);
		kfree(priv);
		iocb->private = NULL;
		/* aio_complete() reports bytes-transferred _and_ faults */
		if (unlikely(kiocbIsCancelled(iocb)))
			aio_put_req(iocb);
		else
			aio_complete(iocb,
				req->actual ? req->actual : req->status,
				req->status);
	} else {
		/* retry() won't report both; so we hide some faults */
		if (unlikely(0 != req->status))
			DBG(epdata->dev, "%s fault %d len %d\n",
				ep->name, req->status, req->actual);

		priv->buf = req->buf;
		priv->actual = req->actual;
		kick_iocb(iocb);
	}
	spin_unlock(&epdata->dev->lock);

	usb_ep_free_request(ep, req);
	put_ep(epdata);
}

static ssize_t
ep_aio_rwtail(
	struct kiocb	*iocb,
	char		*buf,
	size_t		len,
	struct ep_data	*epdata,
	char __user	*ubuf
)
{
	struct kiocb_priv	*priv = (void *) &iocb->private;
	struct usb_request	*req;
	ssize_t			value;

	priv = kmalloc(sizeof *priv, GFP_KERNEL);
	if (!priv) {
		value = -ENOMEM;
fail:
		kfree(buf);
		return value;
	}
	iocb->private = priv;
	priv->ubuf = ubuf;

	value = get_ready_ep(iocb->ki_filp->f_flags, epdata);
	if (unlikely(value < 0)) {
		kfree(priv);
		goto fail;
	}

	iocb->ki_cancel = ep_aio_cancel;
	get_ep(epdata);
	priv->epdata = epdata;
	priv->actual = 0;

	/* each kiocb is coupled to one usb_request, but we can't
	 * allocate or submit those if the host disconnected.
	 */
	spin_lock_irq(&epdata->dev->lock);
	if (likely(epdata->ep)) {
		req = usb_ep_alloc_request(epdata->ep, GFP_ATOMIC);
		if (likely(req)) {
			priv->req = req;
			req->buf = buf;
			req->length = len;
			req->complete = ep_aio_complete;
			req->context = iocb;
			value = usb_ep_queue(epdata->ep, req, GFP_ATOMIC);
			if (unlikely(0 != value))
				usb_ep_free_request(epdata->ep, req);
		} else
			value = -EAGAIN;
	} else
		value = -ENODEV;
	spin_unlock_irq(&epdata->dev->lock);

	up(&epdata->lock);

	if (unlikely(value)) {
		kfree(priv);
		put_ep(epdata);
	} else
		value = -EIOCBQUEUED;
	return value;
}

static ssize_t
ep_aio_read(struct kiocb *iocb, char __user *ubuf, size_t len, loff_t o)
{
	struct ep_data		*epdata = iocb->ki_filp->private_data;
	char			*buf;

	if (unlikely(epdata->desc.bEndpointAddress & USB_DIR_IN))
		return -EINVAL;
	buf = kmalloc(len, GFP_KERNEL);
	if (unlikely(!buf))
		return -ENOMEM;
	iocb->ki_retry = ep_aio_read_retry;
	return ep_aio_rwtail(iocb, buf, len, epdata, ubuf);
}

static ssize_t
ep_aio_write(struct kiocb *iocb, const char __user *ubuf, size_t len, loff_t o)
{
	struct ep_data		*epdata = iocb->ki_filp->private_data;
	char			*buf;

	if (unlikely(!(epdata->desc.bEndpointAddress & USB_DIR_IN)))
		return -EINVAL;
	buf = kmalloc(len, GFP_KERNEL);
	if (unlikely(!buf))
		return -ENOMEM;
	if (unlikely(copy_from_user(buf, ubuf, len) != 0)) {
		kfree(buf);
		return -EFAULT;
	}
	return ep_aio_rwtail(iocb, buf, len, epdata, NULL);
}

/*----------------------------------------------------------------------*/

/* used after endpoint configuration */
static struct file_operations ep_io_operations = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,

	.read =		ep_read,
	.write =	ep_write,
	.ioctl =	ep_ioctl,
	.release =	ep_release,

	.aio_read =	ep_aio_read,
	.aio_write =	ep_aio_write,
};

/* ENDPOINT INITIALIZATION
 *
 *     fd = open ("/dev/gadget/$ENDPOINT", O_RDWR)
 *     status = write (fd, descriptors, sizeof descriptors)
 *
 * That write establishes the endpoint configuration, configuring
 * the controller to process bulk, interrupt, or isochronous transfers
 * at the right maxpacket size, and so on.
 *
 * The descriptors are message type 1, identified by a host order u32
 * at the beginning of what's written.  Descriptor order is: full/low
 * speed descriptor, then optional high speed descriptor.
 */
static ssize_t
ep_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
	struct ep_data		*data = fd->private_data;
	struct usb_ep		*ep;
	u32			tag;
	int			value;

	if ((value = down_interruptible (&data->lock)) < 0)
		return value;

	if (data->state != STATE_EP_READY) {
		value = -EL2HLT;
		goto fail;
	}

	value = len;
	if (len < USB_DT_ENDPOINT_SIZE + 4)
		goto fail0;

	/* we might need to change message format someday */
	if (copy_from_user (&tag, buf, 4)) {
		goto fail1;
	}
	if (tag != 1) {
		DBG(data->dev, "config %s, bad tag %d\n", data->name, tag);
		goto fail0;
	}
	buf += 4;
	len -= 4;

	/* NOTE:  audio endpoint extensions not accepted here;
	 * just don't include the extra bytes.
	 */

	/* full/low speed descriptor, then high speed */
	if (copy_from_user (&data->desc, buf, USB_DT_ENDPOINT_SIZE)) {
		goto fail1;
	}
	if (data->desc.bLength != USB_DT_ENDPOINT_SIZE
			|| data->desc.bDescriptorType != USB_DT_ENDPOINT)
		goto fail0;
	if (len != USB_DT_ENDPOINT_SIZE) {
		if (len != 2 * USB_DT_ENDPOINT_SIZE)
			goto fail0;
		if (copy_from_user (&data->hs_desc, buf + USB_DT_ENDPOINT_SIZE,
					USB_DT_ENDPOINT_SIZE)) {
			goto fail1;
		}
		if (data->hs_desc.bLength != USB_DT_ENDPOINT_SIZE
				|| data->hs_desc.bDescriptorType
					!= USB_DT_ENDPOINT) {
			DBG(data->dev, "config %s, bad hs length or type\n",
					data->name);
			goto fail0;
		}
	}
	value = len;

	spin_lock_irq (&data->dev->lock);
	if (data->dev->state == STATE_DEV_UNBOUND) {
		value = -ENOENT;
		goto gone;
	} else if ((ep = data->ep) == NULL) {
		value = -ENODEV;
		goto gone;
	}
	switch (data->dev->gadget->speed) {
	case USB_SPEED_LOW:
	case USB_SPEED_FULL:
		value = usb_ep_enable (ep, &data->desc);
		if (value == 0)
			data->state = STATE_EP_ENABLED;
		break;
#ifdef	HIGHSPEED
	case USB_SPEED_HIGH:
		/* fails if caller didn't provide that descriptor... */
		value = usb_ep_enable (ep, &data->hs_desc);
		if (value == 0)
			data->state = STATE_EP_ENABLED;
		break;
#endif
	default:
		DBG (data->dev, "unconnected, %s init deferred\n",
				data->name);
		data->state = STATE_EP_DEFER_ENABLE;
	}
	if (value == 0)
		fd->f_op = &ep_io_operations;
gone:
	spin_unlock_irq (&data->dev->lock);
	if (value < 0) {
fail:
		data->desc.bDescriptorType = 0;
		data->hs_desc.bDescriptorType = 0;
	}
	up (&data->lock);
	return value;
fail0:
	value = -EINVAL;
	goto fail;
fail1:
	value = -EFAULT;
	goto fail;
}

static int
ep_open (struct inode *inode, struct file *fd)
{
	struct ep_data		*data = inode->u.generic_ip;
	int			value = -EBUSY;

	if (down_interruptible (&data->lock) != 0)
		return -EINTR;
	spin_lock_irq (&data->dev->lock);
	if (data->dev->state == STATE_DEV_UNBOUND)
		value = -ENOENT;
	else if (data->state == STATE_EP_DISABLED) {
		value = 0;
		data->state = STATE_EP_READY;
		get_ep (data);
		fd->private_data = data;
		VDEBUG (data->dev, "%s ready\n", data->name);
	} else
		DBG (data->dev, "%s state %d\n",
			data->name, data->state);
	spin_unlock_irq (&data->dev->lock);
	up (&data->lock);
	return value;
}

/* used before endpoint configuration */
static struct file_operations ep_config_operations = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,

	.open =		ep_open,
	.write =	ep_config,
	.release =	ep_release,
};

/*----------------------------------------------------------------------*/

/* EP0 IMPLEMENTATION can be partly in userspace.
 *
 * Drivers that use this facility receive various events, including
 * control requests the kernel doesn't handle.  Drivers that don't
 * use this facility may be too simple-minded for real applications.
 */

static inline void ep0_readable (struct dev_data *dev)
{
	wake_up (&dev->wait);
	kill_fasync (&dev->fasync, SIGIO, POLL_IN);
}

static void clean_req (struct usb_ep *ep, struct usb_request *req)
{
	struct dev_data		*dev = ep->driver_data;

	if (req->buf != dev->rbuf) {
		usb_ep_free_buffer (ep, req->buf, req->dma, req->length);
		req->buf = dev->rbuf;
		req->dma = DMA_ADDR_INVALID;
	}
	req->complete = epio_complete;
	dev->setup_out_ready = 0;
}

static void ep0_complete (struct usb_ep *ep, struct usb_request *req)
{
	struct dev_data		*dev = ep->driver_data;
	int			free = 1;

	/* for control OUT, data must still get to userspace */
	if (!dev->setup_in) {
		dev->setup_out_error = (req->status != 0);
		if (!dev->setup_out_error)
			free = 0;
		dev->setup_out_ready = 1;
		ep0_readable (dev);
	} else if (dev->state == STATE_SETUP)
		dev->state = STATE_CONNECTED;

	/* clean up as appropriate */
	if (free && req->buf != &dev->rbuf)
		clean_req (ep, req);
	req->complete = epio_complete;
}

static int setup_req (struct usb_ep *ep, struct usb_request *req, u16 len)
{
	struct dev_data	*dev = ep->driver_data;

	if (dev->setup_out_ready) {
		DBG (dev, "ep0 request busy!\n");
		return -EBUSY;
	}
	if (len > sizeof (dev->rbuf))
		req->buf = usb_ep_alloc_buffer (ep, len, &req->dma, GFP_ATOMIC);
	if (req->buf == 0) {
		req->buf = dev->rbuf;
		return -ENOMEM;
	}
	req->complete = ep0_complete;
	req->length = len;
	return 0;
}

static ssize_t
ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
{
	struct dev_data			*dev = fd->private_data;
	ssize_t				retval;
	enum ep0_state			state;

	spin_lock_irq (&dev->lock);

	/* report fd mode change before acting on it */
	if (dev->setup_abort) {
		dev->setup_abort = 0;
		retval = -EIDRM;
		goto done;
	}

	/* control DATA stage */
	if ((state = dev->state) == STATE_SETUP) {

		if (dev->setup_in) {		/* stall IN */
			VDEBUG(dev, "ep0in stall\n");
			(void) usb_ep_set_halt (dev->gadget->ep0);
			retval = -EL2HLT;
			dev->state = STATE_CONNECTED;

		} else if (len == 0) {		/* ack SET_CONFIGURATION etc */
			struct usb_ep		*ep = dev->gadget->ep0;
			struct usb_request	*req = dev->req;

			if ((retval = setup_req (ep, req, 0)) == 0)
				retval = usb_ep_queue (ep, req, GFP_ATOMIC);
			dev->state = STATE_CONNECTED;

			/* assume that was SET_CONFIGURATION */
			if (dev->current_config) {
				unsigned power;
#ifdef	HIGHSPEED
				if (dev->gadget->speed == USB_SPEED_HIGH)
					power = dev->hs_config->bMaxPower;
				else
#endif
					power = dev->config->bMaxPower;
				usb_gadget_vbus_draw(dev->gadget, 2 * power);
			}

		} else {			/* collect OUT data */
			if ((fd->f_flags & O_NONBLOCK) != 0
					&& !dev->setup_out_ready) {
				retval = -EAGAIN;
				goto done;
			}
			spin_unlock_irq (&dev->lock);
			retval = wait_event_interruptible (dev->wait,
					dev->setup_out_ready != 0);

			/* FIXME state could change from under us */
			spin_lock_irq (&dev->lock);
			if (retval)
				goto done;
			if (dev->setup_out_error)
				retval = -EIO;
			else {
				len = min (len, (size_t)dev->req->actual);
// FIXME don't call this with the spinlock held ...
				if (copy_to_user (buf, &dev->req->buf, len))
					retval = -EFAULT;
				clean_req (dev->gadget->ep0, dev->req);
				/* NOTE userspace can't yet choose to stall */
			}
		}
		goto done;
	}

	/* else normal: return event data */
	if (len < sizeof dev->event [0]) {
		retval = -EINVAL;
		goto done;
	}
	len -= len % sizeof (struct usb_gadgetfs_event);
	dev->usermode_setup = 1;

scan:
	/* return queued events right away */
	if (dev->ev_next != 0) {
		unsigned		i, n;
		int			tmp = dev->ev_next;

		len = min (len, tmp * sizeof (struct usb_gadgetfs_event));
		n = len / sizeof (struct usb_gadgetfs_event);

		/* ep0 can't deliver events when STATE_SETUP */
		for (i = 0; i < n; i++) {
			if (dev->event [i].type == GADGETFS_SETUP) {
				len = n = i + 1;
				len *= sizeof (struct usb_gadgetfs_event);
				n = 0;
				break;
			}
		}
		spin_unlock_irq (&dev->lock);
		if (copy_to_user (buf, &dev->event, len))
			retval = -EFAULT;
		else
			retval = len;
		if (len > 0) {
			len /= sizeof (struct usb_gadgetfs_event);

			/* NOTE this doesn't guard against broken drivers;
			 * concurrent ep0 readers may lose events.
			 */
			spin_lock_irq (&dev->lock);
			dev->ev_next -= len;
			if (dev->ev_next != 0)
				memmove (&dev->event, &dev->event [len],
					sizeof (struct usb_gadgetfs_event)
						* (tmp - len));
			if (n == 0)
				dev->state = STATE_SETUP;
			spin_unlock_irq (&dev->lock);
		}
		return retval;
	}
	if (fd->f_flags & O_NONBLOCK) {
		retval = -EAGAIN;
		goto done;
	}

	switch (state) {
	default:
		DBG (dev, "fail %s, state %d\n", __FUNCTION__, state);
		retval = -ESRCH;
		break;
	case STATE_UNCONNECTED:
	case STATE_CONNECTED:
		spin_unlock_irq (&dev->lock);
		DBG (dev, "%s wait\n", __FUNCTION__);

		/* wait for events */
		retval = wait_event_interruptible (dev->wait,
				dev->ev_next != 0);
		if (retval < 0)
			return retval;
		spin_lock_irq (&dev->lock);
		goto scan;
	}

done:
	spin_unlock_irq (&dev->lock);
	return retval;
}

static struct usb_gadgetfs_event *
next_event (struct dev_data *dev, enum usb_gadgetfs_event_type type)
{
	struct usb_gadgetfs_event	*event;
	unsigned			i;

	switch (type) {
	/* these events purge the queue */
	case GADGETFS_DISCONNECT:
		if (dev->state == STATE_SETUP)
			dev->setup_abort = 1;
		// FALL THROUGH
	case GADGETFS_CONNECT:
		dev->ev_next = 0;
		break;
	case GADGETFS_SETUP:		/* previous request timed out */
	case GADGETFS_SUSPEND:		/* same effect */
		/* these events can't be repeated */
		for (i = 0; i != dev->ev_next; i++) {
			if (dev->event [i].type != type)
				continue;
			DBG (dev, "discard old event %d\n", type);
			dev->ev_next--;
			if (i == dev->ev_next)
				break;
			/* indices start at zero, for simplicity */
			memmove (&dev->event [i], &dev->event [i + 1],
				sizeof (struct usb_gadgetfs_event)
					* (dev->ev_next - i));
		}
		break;
	default:
		BUG ();
	}
	event = &dev->event [dev->ev_next++];
	BUG_ON (dev->ev_next > N_EVENT);
	VDEBUG (dev, "ev %d, next %d\n", type, dev->ev_next);
	memset (event, 0, sizeof *event);
	event->type = type;
	return event;
}

static ssize_t
ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
	struct dev_data		*dev = fd->private_data;
	ssize_t			retval = -ESRCH;

	spin_lock_irq (&dev->lock);

	/* report fd mode change before acting on it */
	if (dev->setup_abort) {
		dev->setup_abort = 0;
		retval = -EIDRM;

	/* data and/or status stage for control request */
	} else if (dev->state == STATE_SETUP) {

		/* IN DATA+STATUS caller makes len <= wLength */
		if (dev->setup_in) {
			retval = setup_req (dev->gadget->ep0, dev->req, len);
			if (retval == 0) {
				spin_unlock_irq (&dev->lock);
				if (copy_from_user (dev->req->buf, buf, len))
					retval = -EFAULT;
				else
					retval = usb_ep_queue (
						dev->gadget->ep0, dev->req,
						GFP_KERNEL);
				if (retval < 0) {
					spin_lock_irq (&dev->lock);
					clean_req (dev->gadget->ep0, dev->req);
					spin_unlock_irq (&dev->lock);
				} else
					retval = len;

				return retval;
			}

		/* can stall some OUT transfers */
		} else if (dev->setup_can_stall) {
			VDEBUG(dev, "ep0out stall\n");
			(void) usb_ep_set_halt (dev->gadget->ep0);
			retval = -EL2HLT;
			dev->state = STATE_CONNECTED;
		} else {
			DBG(dev, "bogus ep0out stall!\n");
		}
	} else
		DBG (dev, "fail %s, state %d\n", __FUNCTION__, dev->state);

	spin_unlock_irq (&dev->lock);
	return retval;
}

static int
ep0_fasync (int f, struct file *fd, int on)
{
	struct dev_data		*dev = fd->private_data;
	// caller must F_SETOWN before signal delivery happens
	VDEBUG (dev, "%s %s\n", __FUNCTION__, on ? "on" : "off");
	return fasync_helper (f, fd, on, &dev->fasync);
}

static struct usb_gadget_driver gadgetfs_driver;

static int
dev_release (struct inode *inode, struct file *fd)
{
	struct dev_data		*dev = fd->private_data;

	/* closing ep0 === shutdown all */

	usb_gadget_unregister_driver (&gadgetfs_driver);

	/* at this point "good" hardware has disconnected the
	 * device from USB; the host won't see it any more.
	 * alternatively, all host requests will time out.
	 */

	fasync_helper (-1, fd, 0, &dev->fasync);
	kfree (dev->buf);
	dev->buf = NULL;
	put_dev (dev);

	/* other endpoints were all decoupled from this device */
	dev->state = STATE_DEV_DISABLED;
	return 0;
}

static int dev_ioctl (struct inode *inode, struct file *fd,
		unsigned code, unsigned long value)
{
	struct dev_data		*dev = fd->private_data;
	struct usb_gadget	*gadget = dev->gadget;

	if (gadget->ops->ioctl)
		return gadget->ops->ioctl (gadget, code, value);
	return -ENOTTY;
}

/* used after device configuration */
static struct file_operations ep0_io_operations = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,

	.read =		ep0_read,
	.write =	ep0_write,
	.fasync =	ep0_fasync,
	// .poll =	ep0_poll,
	.ioctl =	dev_ioctl,
	.release =	dev_release,
};

/*----------------------------------------------------------------------*/

/* The in-kernel gadget driver handles most ep0 issues, in particular
 * enumerating the single configuration (as provided from user space).
 *
 * Unrecognized ep0 requests may be handled in user space.
 */

#ifdef	HIGHSPEED
static void make_qualifier (struct dev_data *dev)
{
	struct usb_qualifier_descriptor		qual;
	struct usb_device_descriptor		*desc;

	qual.bLength = sizeof qual;
	qual.bDescriptorType = USB_DT_DEVICE_QUALIFIER;
	qual.bcdUSB = __constant_cpu_to_le16 (0x0200);

	desc = dev->dev;
	qual.bDeviceClass = desc->bDeviceClass;
	qual.bDeviceSubClass = desc->bDeviceSubClass;
	qual.bDeviceProtocol = desc->bDeviceProtocol;

	/* assumes ep0 uses the same value for both speeds ... */
	qual.bMaxPacketSize0 = desc->bMaxPacketSize0;

	qual.bNumConfigurations = 1;
	qual.bRESERVED = 0;

	memcpy (dev->rbuf, &qual, sizeof qual);
}
#endif

static int
config_buf (struct dev_data *dev, u8 type, unsigned index)
{
	int		len;
#ifdef HIGHSPEED
	int		hs;
#endif

	/* only one configuration */
	if (index > 0)
		return -EINVAL;

#ifdef HIGHSPEED
	hs = (dev->gadget->speed == USB_SPEED_HIGH);
	if (type == USB_DT_OTHER_SPEED_CONFIG)
		hs = !hs;
	if (hs) {
		dev->req->buf = dev->hs_config;
		len = le16_to_cpup (&dev->hs_config->wTotalLength);
	} else
#endif
	{
		dev->req->buf = dev->config;
		len = le16_to_cpup (&dev->config->wTotalLength);
	}
	((u8 *)dev->req->buf) [1] = type;
	return len;
}

static int
gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
{
	struct dev_data			*dev = get_gadget_data (gadget);
	struct usb_request		*req = dev->req;
	int				value = -EOPNOTSUPP;
	struct usb_gadgetfs_event	*event;
	u16				w_value = le16_to_cpu(ctrl->wValue);
	u16				w_length = le16_to_cpu(ctrl->wLength);

	spin_lock (&dev->lock);
	dev->setup_abort = 0;
	if (dev->state == STATE_UNCONNECTED) {
		struct usb_ep	*ep;
		struct ep_data	*data;

		dev->state = STATE_CONNECTED;
		dev->dev->bMaxPacketSize0 = gadget->ep0->maxpacket;

#ifdef	HIGHSPEED
		if (gadget->speed == USB_SPEED_HIGH && dev->hs_config == 0) {
			ERROR (dev, "no high speed config??\n");
			return -EINVAL;
		}
#endif	/* HIGHSPEED */

		INFO (dev, "connected\n");
		event = next_event (dev, GADGETFS_CONNECT);
		event->u.speed = gadget->speed;
		ep0_readable (dev);

		list_for_each_entry (ep, &gadget->ep_list, ep_list) {
			data = ep->driver_data;
			/* ... down_trylock (&data->lock) ... */
			if (data->state != STATE_EP_DEFER_ENABLE)
				continue;
#ifdef	HIGHSPEED
			if (gadget->speed == USB_SPEED_HIGH)
				value = usb_ep_enable (ep, &data->hs_desc);
			else
#endif	/* HIGHSPEED */
				value = usb_ep_enable (ep, &data->desc);
			if (value) {
				ERROR (dev, "deferred %s enable --> %d\n",
					data->name, value);
				continue;
			}
			data->state = STATE_EP_ENABLED;
			wake_up (&data->wait);
			DBG (dev, "woke up %s waiters\n", data->name);
		}

	/* host may have given up waiting for response.  we can miss control
	 * requests handled lower down (device/endpoint status and features);
	 * then ep0_{read,write} will report the wrong status. controller
	 * driver will have aborted pending i/o.
	 */
	} else if (dev->state == STATE_SETUP)
		dev->setup_abort = 1;

	req->buf = dev->rbuf;
	req->dma = DMA_ADDR_INVALID;
	req->context = NULL;
	value = -EOPNOTSUPP;
	switch (ctrl->bRequest) {

	case USB_REQ_GET_DESCRIPTOR:
		if (ctrl->bRequestType != USB_DIR_IN)
			goto unrecognized;
		switch (w_value >> 8) {

		case USB_DT_DEVICE:
			value = min (w_length, (u16) sizeof *dev->dev);
			req->buf = dev->dev;
			break;
#ifdef	HIGHSPEED
		case USB_DT_DEVICE_QUALIFIER:
			if (!dev->hs_config)
				break;
			value = min (w_length, (u16)
				sizeof (struct usb_qualifier_descriptor));
			make_qualifier (dev);
			break;
		case USB_DT_OTHER_SPEED_CONFIG:
			// FALLTHROUGH
#endif
		case USB_DT_CONFIG:
			value = config_buf (dev,
					w_value >> 8,
					w_value & 0xff);
			if (value >= 0)
				value = min (w_length, (u16) value);
			break;
		case USB_DT_STRING:
			goto unrecognized;

		default:		// all others are errors
			break;
		}
		break;

	/* currently one config, two speeds */
	case USB_REQ_SET_CONFIGURATION:
		if (ctrl->bRequestType != 0)
			break;
		if (0 == (u8) w_value) {
			value = 0;
			dev->current_config = 0;
			usb_gadget_vbus_draw(gadget, 8 /* mA */ );
			// user mode expected to disable endpoints
		} else {
			u8	config, power;
#ifdef	HIGHSPEED
			if (gadget->speed == USB_SPEED_HIGH) {
				config = dev->hs_config->bConfigurationValue;
				power = dev->hs_config->bMaxPower;
			} else
#endif
			{
				config = dev->config->bConfigurationValue;
				power = dev->config->bMaxPower;
			}

			if (config == (u8) w_value) {
				value = 0;
				dev->current_config = config;
				usb_gadget_vbus_draw(gadget, 2 * power);
			}
		}

		/* report SET_CONFIGURATION like any other control request,
		 * except that usermode may not stall this.  the next
		 * request mustn't be allowed start until this finishes:
		 * endpoints and threads set up, etc.
		 *
		 * NOTE:  older PXA hardware (before PXA 255: without UDCCFR)
		 * has bad/racey automagic that prevents synchronizing here.
		 * even kernel mode drivers often miss them.
		 */
		if (value == 0) {
			INFO (dev, "configuration #%d\n", dev->current_config);
			if (dev->usermode_setup) {
				dev->setup_can_stall = 0;
				goto delegate;
			}
		}
		break;

#ifndef	CONFIG_USB_GADGETFS_PXA2XX
	/* PXA automagically handles this request too */
	case USB_REQ_GET_CONFIGURATION:
		if (ctrl->bRequestType != 0x80)
			break;
		*(u8 *)req->buf = dev->current_config;
		value = min (w_length, (u16) 1);
		break;
#endif

	default:
unrecognized:
		VDEBUG (dev, "%s req%02x.%02x v%04x i%04x l%d\n",
			dev->usermode_setup ? "delegate" : "fail",
			ctrl->bRequestType, ctrl->bRequest,
			w_value, le16_to_cpu(ctrl->wIndex), w_length);

		/* if there's an ep0 reader, don't stall */
		if (dev->usermode_setup) {
			dev->setup_can_stall = 1;
delegate:
			dev->setup_in = (ctrl->bRequestType & USB_DIR_IN)
						? 1 : 0;
			dev->setup_out_ready = 0;
			dev->setup_out_error = 0;
			value = 0;

			/* read DATA stage for OUT right away */
			if (unlikely (!dev->setup_in && w_length)) {
				value = setup_req (gadget->ep0, dev->req,
							w_length);
				if (value < 0)
					break;
				value = usb_ep_queue (gadget->ep0, dev->req,
							GFP_ATOMIC);
				if (value < 0) {
					clean_req (gadget->ep0, dev->req);
					break;
				}

				/* we can't currently stall these */
				dev->setup_can_stall = 0;
			}

			/* state changes when reader collects event */
			event = next_event (dev, GADGETFS_SETUP);
			event->u.setup = *ctrl;
			ep0_readable (dev);
			spin_unlock (&dev->lock);
			return 0;
		}
	}

	/* proceed with data transfer and status phases? */
	if (value >= 0 && dev->state != STATE_SETUP) {
		req->length = value;
		req->zero = value < w_length;
		value = usb_ep_queue (gadget->ep0, req, GFP_ATOMIC);
		if (value < 0) {
			DBG (dev, "ep_queue --> %d\n", value);
			req->status = 0;
		}
	}

	/* device stalls when value < 0 */
	spin_unlock (&dev->lock);
	return value;
}

static void destroy_ep_files (struct dev_data *dev)
{
	struct list_head	*entry, *tmp;

	DBG (dev, "%s %d\n", __FUNCTION__, dev->state);

	/* dev->state must prevent interference */
restart:
	spin_lock_irq (&dev->lock);
	list_for_each_safe (entry, tmp, &dev->epfiles) {
		struct ep_data	*ep;
		struct inode	*parent;
		struct dentry	*dentry;

		/* break link to FS */
		ep = list_entry (entry, struct ep_data, epfiles);
		list_del_init (&ep->epfiles);
		dentry = ep->dentry;
		ep->dentry = NULL;
		parent = dentry->d_parent->d_inode;

		/* break link to controller */
		if (ep->state == STATE_EP_ENABLED)
			(void) usb_ep_disable (ep->ep);
		ep->state = STATE_EP_UNBOUND;
		usb_ep_free_request (ep->ep, ep->req);
		ep->ep = NULL;
		wake_up (&ep->wait);
		put_ep (ep);

		spin_unlock_irq (&dev->lock);

		/* break link to dcache */
		down (&parent->i_sem);
		d_delete (dentry);
		dput (dentry);
		up (&parent->i_sem);

		/* fds may still be open */
		goto restart;
	}
	spin_unlock_irq (&dev->lock);
}


static struct inode *
gadgetfs_create_file (struct super_block *sb, char const *name,
		void *data, struct file_operations *fops,
		struct dentry **dentry_p);

static int activate_ep_files (struct dev_data *dev)
{
	struct usb_ep	*ep;

	gadget_for_each_ep (ep, dev->gadget) {
		struct ep_data	*data;

		data = kmalloc (sizeof *data, GFP_KERNEL);
		if (!data)
			goto enomem;
		memset (data, 0, sizeof data);
		data->state = STATE_EP_DISABLED;
		init_MUTEX (&data->lock);
		init_waitqueue_head (&data->wait);

		strncpy (data->name, ep->name, sizeof (data->name) - 1);
		atomic_set (&data->count, 1);
		data->dev = dev;
		get_dev (dev);

		data->ep = ep;
		ep->driver_data = data;

		data->req = usb_ep_alloc_request (ep, GFP_KERNEL);
		if (!data->req)
			goto enomem;

		data->inode = gadgetfs_create_file (dev->sb, data->name,
				data, &ep_config_operations,
				&data->dentry);
		if (!data->inode) {
			kfree (data);
			goto enomem;
		}
		list_add_tail (&data->epfiles, &dev->epfiles);
	}
	return 0;

enomem:
	DBG (dev, "%s enomem\n", __FUNCTION__);
	destroy_ep_files (dev);
	return -ENOMEM;
}

static void
gadgetfs_unbind (struct usb_gadget *gadget)
{
	struct dev_data		*dev = get_gadget_data (gadget);

	DBG (dev, "%s\n", __FUNCTION__);

	spin_lock_irq (&dev->lock);
	dev->state = STATE_DEV_UNBOUND;
	spin_unlock_irq (&dev->lock);

	destroy_ep_files (dev);
	gadget->ep0->driver_data = NULL;
	set_gadget_data (gadget, NULL);

	/* we've already been disconnected ... no i/o is active */
	if (dev->req)
		usb_ep_free_request (gadget->ep0, dev->req);
	DBG (dev, "%s done\n", __FUNCTION__);
	put_dev (dev);
}

static struct dev_data		*the_device;

static int
gadgetfs_bind (struct usb_gadget *gadget)
{
	struct dev_data		*dev = the_device;

	if (!dev)
		return -ESRCH;
	if (0 != strcmp (CHIP, gadget->name)) {
		printk (KERN_ERR "%s expected %s controller not %s\n",
			shortname, CHIP, gadget->name);
		return -ENODEV;
	}

	set_gadget_data (gadget, dev);
	dev->gadget = gadget;
	gadget->ep0->driver_data = dev;
	dev->dev->bMaxPacketSize0 = gadget->ep0->maxpacket;

	/* preallocate control response and buffer */
	dev->req = usb_ep_alloc_request (gadget->ep0, GFP_KERNEL);
	if (!dev->req)
		goto enomem;
	dev->req->context = NULL;
	dev->req->complete = epio_complete;

	if (activate_ep_files (dev) < 0)
		goto enomem;

	INFO (dev, "bound to %s driver\n", gadget->name);
	dev->state = STATE_UNCONNECTED;
	get_dev (dev);
	return 0;

enomem:
	gadgetfs_unbind (gadget);
	return -ENOMEM;
}

static void
gadgetfs_disconnect (struct usb_gadget *gadget)
{
	struct dev_data		*dev = get_gadget_data (gadget);

	if (dev->state == STATE_UNCONNECTED) {
		DBG (dev, "already unconnected\n");
		return;
	}
	dev->state = STATE_UNCONNECTED;

	INFO (dev, "disconnected\n");
	spin_lock (&dev->lock);
	next_event (dev, GADGETFS_DISCONNECT);
	ep0_readable (dev);
	spin_unlock (&dev->lock);
}

static void
gadgetfs_suspend (struct usb_gadget *gadget)
{
	struct dev_data		*dev = get_gadget_data (gadget);

	INFO (dev, "suspended from state %d\n", dev->state);
	spin_lock (&dev->lock);
	switch (dev->state) {
	case STATE_SETUP:		// VERY odd... host died??
	case STATE_CONNECTED:
	case STATE_UNCONNECTED:
		next_event (dev, GADGETFS_SUSPEND);
		ep0_readable (dev);
		/* FALLTHROUGH */
	default:
		break;
	}
	spin_unlock (&dev->lock);
}

static struct usb_gadget_driver gadgetfs_driver = {
#ifdef	HIGHSPEED
	.speed		= USB_SPEED_HIGH,
#else
	.speed		= USB_SPEED_FULL,
#endif
	.function	= (char *) driver_desc,
	.bind		= gadgetfs_bind,
	.unbind		= gadgetfs_unbind,
	.setup		= gadgetfs_setup,
	.disconnect	= gadgetfs_disconnect,
	.suspend	= gadgetfs_suspend,

	.driver 	= {
		.name		= (char *) shortname,
		// .shutdown = ...
		// .suspend = ...
		// .resume = ...
	},
};

/*----------------------------------------------------------------------*/

static void gadgetfs_nop(struct usb_gadget *arg) { }

static int gadgetfs_probe (struct usb_gadget *gadget)
{
	CHIP = gadget->name;
	return -EISNAM;
}

static struct usb_gadget_driver probe_driver = {
	.speed		= USB_SPEED_HIGH,
	.bind		= gadgetfs_probe,
	.unbind		= gadgetfs_nop,
	.setup		= (void *)gadgetfs_nop,
	.disconnect	= gadgetfs_nop,
	.driver 	= {
		.name		= "nop",
	},
};


/* DEVICE INITIALIZATION
 *
 *     fd = open ("/dev/gadget/$CHIP", O_RDWR)
 *     status = write (fd, descriptors, sizeof descriptors)
 *
 * That write establishes the device configuration, so the kernel can
 * bind to the controller ... guaranteeing it can handle enumeration
 * at all necessary speeds.  Descriptor order is:
 *
 * . message tag (u32, host order) ... for now, must be zero; it
 *	would change to support features like multi-config devices
 * . full/low speed config ... all wTotalLength bytes (with interface,
 *	class, altsetting, endpoint, and other descriptors)
 * . high speed config ... all descriptors, for high speed operation;
 * 	this one's optional except for high-speed hardware
 * . device descriptor
 *
 * Endpoints are not yet enabled. Drivers may want to immediately
 * initialize them, using the /dev/gadget/ep* files that are available
 * as soon as the kernel sees the configuration, or they can wait
 * until device configuration and interface altsetting changes create
 * the need to configure (or unconfigure) them.
 *
 * After initialization, the device stays active for as long as that
 * $CHIP file is open.  Events may then be read from that descriptor,
 * such configuration notifications.  More complex drivers will handle
 * some control requests in user space.
 */

static int is_valid_config (struct usb_config_descriptor *config)
{
	return config->bDescriptorType == USB_DT_CONFIG
		&& config->bLength == USB_DT_CONFIG_SIZE
		&& config->bConfigurationValue != 0
		&& (config->bmAttributes & USB_CONFIG_ATT_ONE) != 0
		&& (config->bmAttributes & USB_CONFIG_ATT_WAKEUP) == 0;
	/* FIXME if gadget->is_otg, _must_ include an otg descriptor */
	/* FIXME check lengths: walk to end */
}

static ssize_t
dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
	struct dev_data		*dev = fd->private_data;
	ssize_t			value = len, length = len;
	unsigned		total;
	u32			tag;
	char			*kbuf;

	if (dev->state != STATE_OPENED)
		return -EEXIST;

	if (len < (USB_DT_CONFIG_SIZE + USB_DT_DEVICE_SIZE + 4))
		return -EINVAL;

	/* we might need to change message format someday */
	if (copy_from_user (&tag, buf, 4))
		return -EFAULT;
	if (tag != 0)
		return -EINVAL;
	buf += 4;
	length -= 4;

	kbuf = kmalloc (length, SLAB_KERNEL);
	if (!kbuf)
		return -ENOMEM;
	if (copy_from_user (kbuf, buf, length)) {
		kfree (kbuf);
		return -EFAULT;
	}

	spin_lock_irq (&dev->lock);
	value = -EINVAL;
	if (dev->buf)
		goto fail;
	dev->buf = kbuf;

	/* full or low speed config */
	dev->config = (void *) kbuf;
	total = le16_to_cpup (&dev->config->wTotalLength);
	if (!is_valid_config (dev->config) || total >= length)
		goto fail;
	kbuf += total;
	length -= total;

	/* optional high speed config */
	if (kbuf [1] == USB_DT_CONFIG) {
		dev->hs_config = (void *) kbuf;
		total = le16_to_cpup (&dev->hs_config->wTotalLength);
		if (!is_valid_config (dev->hs_config) || total >= length)
			goto fail;
		kbuf += total;
		length -= total;
	}

	/* could support multiple configs, using another encoding! */

	/* device descriptor (tweaked for paranoia) */
	if (length != USB_DT_DEVICE_SIZE)
		goto fail;
	dev->dev = (void *)kbuf;
	if (dev->dev->bLength != USB_DT_DEVICE_SIZE
			|| dev->dev->bDescriptorType != USB_DT_DEVICE
			|| dev->dev->bNumConfigurations != 1)
		goto fail;
	dev->dev->bNumConfigurations = 1;
	dev->dev->bcdUSB = __constant_cpu_to_le16 (0x0200);

	/* triggers gadgetfs_bind(); then we can enumerate. */
	spin_unlock_irq (&dev->lock);
	value = usb_gadget_register_driver (&gadgetfs_driver);
	if (value != 0) {
		kfree (dev->buf);
		dev->buf = NULL;
	} else {
		/* at this point "good" hardware has for the first time
		 * let the USB the host see us.  alternatively, if users
		 * unplug/replug that will clear all the error state.
		 *
		 * note:  everything running before here was guaranteed
		 * to choke driver model style diagnostics.  from here
		 * on, they can work ... except in cleanup paths that
		 * kick in after the ep0 descriptor is closed.
		 */
		fd->f_op = &ep0_io_operations;
		value = len;
	}
	return value;

fail:
	spin_unlock_irq (&dev->lock);
	pr_debug ("%s: %s fail %Zd, %p\n", shortname, __FUNCTION__, value, dev);
	kfree (dev->buf);
	dev->buf = NULL;
	return value;
}

static int
dev_open (struct inode *inode, struct file *fd)
{
	struct dev_data		*dev = inode->u.generic_ip;
	int			value = -EBUSY;

	if (dev->state == STATE_DEV_DISABLED) {
		dev->ev_next = 0;
		dev->state = STATE_OPENED;
		fd->private_data = dev;
		get_dev (dev);
		value = 0;
	}
	return value;
}

static struct file_operations dev_init_operations = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,

	.open =		dev_open,
	.write =	dev_config,
	.fasync =	ep0_fasync,
	.ioctl =	dev_ioctl,
	.release =	dev_release,
};

/*----------------------------------------------------------------------*/

/* FILESYSTEM AND SUPERBLOCK OPERATIONS
 *
 * Mounting the filesystem creates a controller file, used first for
 * device configuration then later for event monitoring.
 */


/* FIXME PAM etc could set this security policy without mount options
 * if epfiles inherited ownership and permissons from ep0 ...
 */

static unsigned default_uid;
static unsigned default_gid;
static unsigned default_perm = S_IRUSR | S_IWUSR;

module_param (default_uid, uint, 0644);
module_param (default_gid, uint, 0644);
module_param (default_perm, uint, 0644);


static struct inode *
gadgetfs_make_inode (struct super_block *sb,
		void *data, struct file_operations *fops,
		int mode)
{
	struct inode *inode = new_inode (sb);

	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = default_uid;
		inode->i_gid = default_gid;
		inode->i_blksize = PAGE_CACHE_SIZE;
		inode->i_blocks = 0;
		inode->i_atime = inode->i_mtime = inode->i_ctime
				= CURRENT_TIME;
		inode->u.generic_ip = data;
		inode->i_fop = fops;
	}
	return inode;
}

/* creates in fs root directory, so non-renamable and non-linkable.
 * so inode and dentry are paired, until device reconfig.
 */
static struct inode *
gadgetfs_create_file (struct super_block *sb, char const *name,
		void *data, struct file_operations *fops,
		struct dentry **dentry_p)
{
	struct dentry	*dentry;
	struct inode	*inode;

	dentry = d_alloc_name(sb->s_root, name);
	if (!dentry)
		return NULL;

	inode = gadgetfs_make_inode (sb, data, fops,
			S_IFREG | (default_perm & S_IRWXUGO));
	if (!inode) {
		dput(dentry);
		return NULL;
	}
	d_add (dentry, inode);
	*dentry_p = dentry;
	return inode;
}

static struct super_operations gadget_fs_operations = {
	.statfs =	simple_statfs,
	.drop_inode =	generic_delete_inode,
};

static int
gadgetfs_fill_super (struct super_block *sb, void *opts, int silent)
{
	struct inode	*inode;
	struct dentry	*d;
	struct dev_data	*dev;

	if (the_device)
		return -ESRCH;

	/* fake probe to determine $CHIP */
	(void) usb_gadget_register_driver (&probe_driver);
	if (!CHIP)
		return -ENODEV;

	/* superblock */
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = GADGETFS_MAGIC;
	sb->s_op = &gadget_fs_operations;
	sb->s_time_gran = 1;

	/* root inode */
	inode = gadgetfs_make_inode (sb,
			NULL, &simple_dir_operations,
			S_IFDIR | S_IRUGO | S_IXUGO);
	if (!inode)
		return -ENOMEM;
	inode->i_op = &simple_dir_inode_operations;
	if (!(d = d_alloc_root (inode))) {
		iput (inode);
		return -ENOMEM;
	}
	sb->s_root = d;

	/* the ep0 file is named after the controller we expect;
	 * user mode code can use it for sanity checks, like we do.
	 */
	dev = dev_new ();
	if (!dev)
		return -ENOMEM;

	dev->sb = sb;
	if (!(inode = gadgetfs_create_file (sb, CHIP,
				dev, &dev_init_operations,
				&dev->dentry))) {
		put_dev(dev);
		return -ENOMEM;
	}

	/* other endpoint files are available after hardware setup,
	 * from binding to a controller.
	 */
	the_device = dev;
	return 0;
}

/* "mount -t gadgetfs path /dev/gadget" ends up here */
static struct super_block *
gadgetfs_get_sb (struct file_system_type *t, int flags,
		const char *path, void *opts)
{
	return get_sb_single (t, flags, opts, gadgetfs_fill_super);
}

static void
gadgetfs_kill_sb (struct super_block *sb)
{
	kill_litter_super (sb);
	if (the_device) {
		put_dev (the_device);
		the_device = NULL;
	}
}

/*----------------------------------------------------------------------*/

static struct file_system_type gadgetfs_type = {
	.owner		= THIS_MODULE,
	.name		= shortname,
	.get_sb		= gadgetfs_get_sb,
	.kill_sb	= gadgetfs_kill_sb,
};

/*----------------------------------------------------------------------*/

static int __init init (void)
{
	int status;

	status = register_filesystem (&gadgetfs_type);
	if (status == 0)
		pr_info ("%s: %s, version " DRIVER_VERSION "\n",
			shortname, driver_desc);
	return status;
}
module_init (init);

static void __exit cleanup (void)
{
	pr_debug ("unregister %s\n", shortname);
	unregister_filesystem (&gadgetfs_type);
}
module_exit (cleanup);