summaryrefslogtreecommitdiff
path: root/drivers/usb/host/max3421-hcd.c
blob: e7a8e06098535ced93dae0da4deba4ddc6d63016 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * MAX3421 Host Controller driver for USB.
 *
 * Author: David Mosberger-Tang <davidm@egauge.net>
 *
 * (C) Copyright 2014 David Mosberger-Tang <davidm@egauge.net>
 *
 * MAX3421 is a chip implementing a USB 2.0 Full-/Low-Speed host
 * controller on a SPI bus.
 *
 * Based on:
 *	o MAX3421E datasheet
 *		https://datasheets.maximintegrated.com/en/ds/MAX3421E.pdf
 *	o MAX3421E Programming Guide
 *		https://www.hdl.co.jp/ftpdata/utl-001/AN3785.pdf
 *	o gadget/dummy_hcd.c
 *		For USB HCD implementation.
 *	o Arduino MAX3421 driver
 *	     https://github.com/felis/USB_Host_Shield_2.0/blob/master/Usb.cpp
 *
 * This file is licenced under the GPL v2.
 *
 * Important note on worst-case (full-speed) packet size constraints
 * (See USB 2.0 Section 5.6.3 and following):
 *
 *	- control:	  64 bytes
 *	- isochronous:	1023 bytes
 *	- interrupt:	  64 bytes
 *	- bulk:		  64 bytes
 *
 * Since the MAX3421 FIFO size is 64 bytes, we do not have to work about
 * multi-FIFO writes/reads for a single USB packet *except* for isochronous
 * transfers.  We don't support isochronous transfers at this time, so we
 * just assume that a USB packet always fits into a single FIFO buffer.
 *
 * NOTE: The June 2006 version of "MAX3421E Programming Guide"
 * (AN3785) has conflicting info for the RCVDAVIRQ bit:
 *
 *	The description of RCVDAVIRQ says "The CPU *must* clear
 *	this IRQ bit (by writing a 1 to it) before reading the
 *	RCVFIFO data.
 *
 * However, the earlier section on "Programming BULK-IN
 * Transfers" says * that:
 *
 *	After the CPU retrieves the data, it clears the
 *	RCVDAVIRQ bit.
 *
 * The December 2006 version has been corrected and it consistently
 * states the second behavior is the correct one.
 *
 * Synchronous SPI transactions sleep so we can't perform any such
 * transactions while holding a spin-lock (and/or while interrupts are
 * masked).  To achieve this, all SPI transactions are issued from a
 * single thread (max3421_spi_thread).
 */

#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include <linux/of.h>

#include <linux/platform_data/max3421-hcd.h>

#define DRIVER_DESC	"MAX3421 USB Host-Controller Driver"
#define DRIVER_VERSION	"1.0"

/* 11-bit counter that wraps around (USB 2.0 Section 8.3.3): */
#define USB_MAX_FRAME_NUMBER	0x7ff
#define USB_MAX_RETRIES		3 /* # of retries before error is reported */

/*
 * Max. # of times we're willing to retransmit a request immediately in
 * resposne to a NAK.  Afterwards, we fall back on trying once a frame.
 */
#define NAK_MAX_FAST_RETRANSMITS	2

#define POWER_BUDGET	500	/* in mA; use 8 for low-power port testing */

/* Port-change mask: */
#define PORT_C_MASK	((USB_PORT_STAT_C_CONNECTION |	\
			  USB_PORT_STAT_C_ENABLE |	\
			  USB_PORT_STAT_C_SUSPEND |	\
			  USB_PORT_STAT_C_OVERCURRENT | \
			  USB_PORT_STAT_C_RESET) << 16)

#define MAX3421_GPOUT_COUNT	8

enum max3421_rh_state {
	MAX3421_RH_RESET,
	MAX3421_RH_SUSPENDED,
	MAX3421_RH_RUNNING
};

enum pkt_state {
	PKT_STATE_SETUP,	/* waiting to send setup packet to ctrl pipe */
	PKT_STATE_TRANSFER,	/* waiting to xfer transfer_buffer */
	PKT_STATE_TERMINATE	/* waiting to terminate control transfer */
};

enum scheduling_pass {
	SCHED_PASS_PERIODIC,
	SCHED_PASS_NON_PERIODIC,
	SCHED_PASS_DONE
};

/* Bit numbers for max3421_hcd->todo: */
enum {
	ENABLE_IRQ = 0,
	RESET_HCD,
	RESET_PORT,
	CHECK_UNLINK,
	IOPIN_UPDATE
};

struct max3421_dma_buf {
	u8 data[2];
};

struct max3421_hcd {
	spinlock_t lock;

	struct task_struct *spi_thread;

	struct max3421_hcd *next;

	enum max3421_rh_state rh_state;
	/* lower 16 bits contain port status, upper 16 bits the change mask: */
	u32 port_status;

	unsigned active:1;

	struct list_head ep_list;	/* list of EP's with work */

	/*
	 * The following are owned by spi_thread (may be accessed by
	 * SPI-thread without acquiring the HCD lock:
	 */
	u8 rev;				/* chip revision */
	u16 frame_number;
	/*
	 * kmalloc'd buffers guaranteed to be in separate (DMA)
	 * cache-lines:
	 */
	struct max3421_dma_buf *tx;
	struct max3421_dma_buf *rx;
	/*
	 * URB we're currently processing.  Must not be reset to NULL
	 * unless MAX3421E chip is idle:
	 */
	struct urb *curr_urb;
	enum scheduling_pass sched_pass;
	struct usb_device *loaded_dev;	/* dev that's loaded into the chip */
	int loaded_epnum;		/* epnum whose toggles are loaded */
	int urb_done;			/* > 0 -> no errors, < 0: errno */
	size_t curr_len;
	u8 hien;
	u8 mode;
	u8 iopins[2];
	unsigned long todo;
#ifdef DEBUG
	unsigned long err_stat[16];
#endif
};

struct max3421_ep {
	struct usb_host_endpoint *ep;
	struct list_head ep_list;
	u32 naks;
	u16 last_active;		/* frame # this ep was last active */
	enum pkt_state pkt_state;
	u8 retries;
	u8 retransmit;			/* packet needs retransmission */
};

static struct max3421_hcd *max3421_hcd_list;

#define MAX3421_FIFO_SIZE	64

#define MAX3421_SPI_DIR_RD	0	/* read register from MAX3421 */
#define MAX3421_SPI_DIR_WR	1	/* write register to MAX3421 */

/* SPI commands: */
#define MAX3421_SPI_DIR_SHIFT	1
#define MAX3421_SPI_REG_SHIFT	3

#define MAX3421_REG_RCVFIFO	1
#define MAX3421_REG_SNDFIFO	2
#define MAX3421_REG_SUDFIFO	4
#define MAX3421_REG_RCVBC	6
#define MAX3421_REG_SNDBC	7
#define MAX3421_REG_USBIRQ	13
#define MAX3421_REG_USBIEN	14
#define MAX3421_REG_USBCTL	15
#define MAX3421_REG_CPUCTL	16
#define MAX3421_REG_PINCTL	17
#define MAX3421_REG_REVISION	18
#define MAX3421_REG_IOPINS1	20
#define MAX3421_REG_IOPINS2	21
#define MAX3421_REG_GPINIRQ	22
#define MAX3421_REG_GPINIEN	23
#define MAX3421_REG_GPINPOL	24
#define MAX3421_REG_HIRQ	25
#define MAX3421_REG_HIEN	26
#define MAX3421_REG_MODE	27
#define MAX3421_REG_PERADDR	28
#define MAX3421_REG_HCTL	29
#define MAX3421_REG_HXFR	30
#define MAX3421_REG_HRSL	31

enum {
	MAX3421_USBIRQ_OSCOKIRQ_BIT = 0,
	MAX3421_USBIRQ_NOVBUSIRQ_BIT = 5,
	MAX3421_USBIRQ_VBUSIRQ_BIT
};

enum {
	MAX3421_CPUCTL_IE_BIT = 0,
	MAX3421_CPUCTL_PULSEWID0_BIT = 6,
	MAX3421_CPUCTL_PULSEWID1_BIT
};

enum {
	MAX3421_USBCTL_PWRDOWN_BIT = 4,
	MAX3421_USBCTL_CHIPRES_BIT
};

enum {
	MAX3421_PINCTL_GPXA_BIT	= 0,
	MAX3421_PINCTL_GPXB_BIT,
	MAX3421_PINCTL_POSINT_BIT,
	MAX3421_PINCTL_INTLEVEL_BIT,
	MAX3421_PINCTL_FDUPSPI_BIT,
	MAX3421_PINCTL_EP0INAK_BIT,
	MAX3421_PINCTL_EP2INAK_BIT,
	MAX3421_PINCTL_EP3INAK_BIT,
};

enum {
	MAX3421_HI_BUSEVENT_BIT = 0,	/* bus-reset/-resume */
	MAX3421_HI_RWU_BIT,		/* remote wakeup */
	MAX3421_HI_RCVDAV_BIT,		/* receive FIFO data available */
	MAX3421_HI_SNDBAV_BIT,		/* send buffer available */
	MAX3421_HI_SUSDN_BIT,		/* suspend operation done */
	MAX3421_HI_CONDET_BIT,		/* peripheral connect/disconnect */
	MAX3421_HI_FRAME_BIT,		/* frame generator */
	MAX3421_HI_HXFRDN_BIT,		/* host transfer done */
};

enum {
	MAX3421_HCTL_BUSRST_BIT = 0,
	MAX3421_HCTL_FRMRST_BIT,
	MAX3421_HCTL_SAMPLEBUS_BIT,
	MAX3421_HCTL_SIGRSM_BIT,
	MAX3421_HCTL_RCVTOG0_BIT,
	MAX3421_HCTL_RCVTOG1_BIT,
	MAX3421_HCTL_SNDTOG0_BIT,
	MAX3421_HCTL_SNDTOG1_BIT
};

enum {
	MAX3421_MODE_HOST_BIT = 0,
	MAX3421_MODE_LOWSPEED_BIT,
	MAX3421_MODE_HUBPRE_BIT,
	MAX3421_MODE_SOFKAENAB_BIT,
	MAX3421_MODE_SEPIRQ_BIT,
	MAX3421_MODE_DELAYISO_BIT,
	MAX3421_MODE_DMPULLDN_BIT,
	MAX3421_MODE_DPPULLDN_BIT
};

enum {
	MAX3421_HRSL_OK = 0,
	MAX3421_HRSL_BUSY,
	MAX3421_HRSL_BADREQ,
	MAX3421_HRSL_UNDEF,
	MAX3421_HRSL_NAK,
	MAX3421_HRSL_STALL,
	MAX3421_HRSL_TOGERR,
	MAX3421_HRSL_WRONGPID,
	MAX3421_HRSL_BADBC,
	MAX3421_HRSL_PIDERR,
	MAX3421_HRSL_PKTERR,
	MAX3421_HRSL_CRCERR,
	MAX3421_HRSL_KERR,
	MAX3421_HRSL_JERR,
	MAX3421_HRSL_TIMEOUT,
	MAX3421_HRSL_BABBLE,
	MAX3421_HRSL_RESULT_MASK = 0xf,
	MAX3421_HRSL_RCVTOGRD_BIT = 4,
	MAX3421_HRSL_SNDTOGRD_BIT,
	MAX3421_HRSL_KSTATUS_BIT,
	MAX3421_HRSL_JSTATUS_BIT
};

/* Return same error-codes as ohci.h:cc_to_error: */
static const int hrsl_to_error[] = {
	[MAX3421_HRSL_OK] =		0,
	[MAX3421_HRSL_BUSY] =		-EINVAL,
	[MAX3421_HRSL_BADREQ] =		-EINVAL,
	[MAX3421_HRSL_UNDEF] =		-EINVAL,
	[MAX3421_HRSL_NAK] =		-EAGAIN,
	[MAX3421_HRSL_STALL] =		-EPIPE,
	[MAX3421_HRSL_TOGERR] =		-EILSEQ,
	[MAX3421_HRSL_WRONGPID] =	-EPROTO,
	[MAX3421_HRSL_BADBC] =		-EREMOTEIO,
	[MAX3421_HRSL_PIDERR] =		-EPROTO,
	[MAX3421_HRSL_PKTERR] =		-EPROTO,
	[MAX3421_HRSL_CRCERR] =		-EILSEQ,
	[MAX3421_HRSL_KERR] =		-EIO,
	[MAX3421_HRSL_JERR] =		-EIO,
	[MAX3421_HRSL_TIMEOUT] =	-ETIME,
	[MAX3421_HRSL_BABBLE] =		-EOVERFLOW
};

/*
 * See https://www.beyondlogic.org/usbnutshell/usb4.shtml#Control for a
 * reasonable overview of how control transfers use the the IN/OUT
 * tokens.
 */
#define MAX3421_HXFR_BULK_IN(ep)	(0x00 | (ep))	/* bulk or interrupt */
#define MAX3421_HXFR_SETUP		 0x10
#define MAX3421_HXFR_BULK_OUT(ep)	(0x20 | (ep))	/* bulk or interrupt */
#define MAX3421_HXFR_ISO_IN(ep)		(0x40 | (ep))
#define MAX3421_HXFR_ISO_OUT(ep)	(0x60 | (ep))
#define MAX3421_HXFR_HS_IN		 0x80		/* handshake in */
#define MAX3421_HXFR_HS_OUT		 0xa0		/* handshake out */

#define field(val, bit)	((val) << (bit))

static inline s16
frame_diff(u16 left, u16 right)
{
	return ((unsigned) (left - right)) % (USB_MAX_FRAME_NUMBER + 1);
}

static inline struct max3421_hcd *
hcd_to_max3421(struct usb_hcd *hcd)
{
	return (struct max3421_hcd *) hcd->hcd_priv;
}

static inline struct usb_hcd *
max3421_to_hcd(struct max3421_hcd *max3421_hcd)
{
	return container_of((void *) max3421_hcd, struct usb_hcd, hcd_priv);
}

static u8
spi_rd8(struct usb_hcd *hcd, unsigned int reg)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct spi_transfer transfer;
	struct spi_message msg;

	memset(&transfer, 0, sizeof(transfer));

	spi_message_init(&msg);

	max3421_hcd->tx->data[0] =
		(field(reg, MAX3421_SPI_REG_SHIFT) |
		 field(MAX3421_SPI_DIR_RD, MAX3421_SPI_DIR_SHIFT));

	transfer.tx_buf = max3421_hcd->tx->data;
	transfer.rx_buf = max3421_hcd->rx->data;
	transfer.len = 2;

	spi_message_add_tail(&transfer, &msg);
	spi_sync(spi, &msg);

	return max3421_hcd->rx->data[1];
}

static void
spi_wr8(struct usb_hcd *hcd, unsigned int reg, u8 val)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct spi_transfer transfer;
	struct spi_message msg;

	memset(&transfer, 0, sizeof(transfer));

	spi_message_init(&msg);

	max3421_hcd->tx->data[0] =
		(field(reg, MAX3421_SPI_REG_SHIFT) |
		 field(MAX3421_SPI_DIR_WR, MAX3421_SPI_DIR_SHIFT));
	max3421_hcd->tx->data[1] = val;

	transfer.tx_buf = max3421_hcd->tx->data;
	transfer.len = 2;

	spi_message_add_tail(&transfer, &msg);
	spi_sync(spi, &msg);
}

static void
spi_rd_buf(struct usb_hcd *hcd, unsigned int reg, void *buf, size_t len)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct spi_transfer transfer[2];
	struct spi_message msg;

	memset(transfer, 0, sizeof(transfer));

	spi_message_init(&msg);

	max3421_hcd->tx->data[0] =
		(field(reg, MAX3421_SPI_REG_SHIFT) |
		 field(MAX3421_SPI_DIR_RD, MAX3421_SPI_DIR_SHIFT));
	transfer[0].tx_buf = max3421_hcd->tx->data;
	transfer[0].len = 1;

	transfer[1].rx_buf = buf;
	transfer[1].len = len;

	spi_message_add_tail(&transfer[0], &msg);
	spi_message_add_tail(&transfer[1], &msg);
	spi_sync(spi, &msg);
}

static void
spi_wr_buf(struct usb_hcd *hcd, unsigned int reg, void *buf, size_t len)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct spi_transfer transfer[2];
	struct spi_message msg;

	memset(transfer, 0, sizeof(transfer));

	spi_message_init(&msg);

	max3421_hcd->tx->data[0] =
		(field(reg, MAX3421_SPI_REG_SHIFT) |
		 field(MAX3421_SPI_DIR_WR, MAX3421_SPI_DIR_SHIFT));

	transfer[0].tx_buf = max3421_hcd->tx->data;
	transfer[0].len = 1;

	transfer[1].tx_buf = buf;
	transfer[1].len = len;

	spi_message_add_tail(&transfer[0], &msg);
	spi_message_add_tail(&transfer[1], &msg);
	spi_sync(spi, &msg);
}

/*
 * Figure out the correct setting for the LOWSPEED and HUBPRE mode
 * bits.  The HUBPRE bit needs to be set when MAX3421E operates at
 * full speed, but it's talking to a low-speed device (i.e., through a
 * hub).  Setting that bit ensures that every low-speed packet is
 * preceded by a full-speed PRE PID.  Possible configurations:
 *
 * Hub speed:	Device speed:	=>	LOWSPEED bit:	HUBPRE bit:
 *	FULL	FULL		=>	0		0
 *	FULL	LOW		=>	1		1
 *	LOW	LOW		=>	1		0
 *	LOW	FULL		=>	1		0
 */
static void
max3421_set_speed(struct usb_hcd *hcd, struct usb_device *dev)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	u8 mode_lowspeed, mode_hubpre, mode = max3421_hcd->mode;

	mode_lowspeed = BIT(MAX3421_MODE_LOWSPEED_BIT);
	mode_hubpre   = BIT(MAX3421_MODE_HUBPRE_BIT);
	if (max3421_hcd->port_status & USB_PORT_STAT_LOW_SPEED) {
		mode |=  mode_lowspeed;
		mode &= ~mode_hubpre;
	} else if (dev->speed == USB_SPEED_LOW) {
		mode |= mode_lowspeed | mode_hubpre;
	} else {
		mode &= ~(mode_lowspeed | mode_hubpre);
	}
	if (mode != max3421_hcd->mode) {
		max3421_hcd->mode = mode;
		spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);
	}

}

/*
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_set_address(struct usb_hcd *hcd, struct usb_device *dev, int epnum,
		    int force_toggles)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	int old_epnum, same_ep, rcvtog, sndtog;
	struct usb_device *old_dev;
	u8 hctl;

	old_dev = max3421_hcd->loaded_dev;
	old_epnum = max3421_hcd->loaded_epnum;

	same_ep = (dev == old_dev && epnum == old_epnum);
	if (same_ep && !force_toggles)
		return;

	if (old_dev && !same_ep) {
		/* save the old end-points toggles: */
		u8 hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);

		rcvtog = (hrsl >> MAX3421_HRSL_RCVTOGRD_BIT) & 1;
		sndtog = (hrsl >> MAX3421_HRSL_SNDTOGRD_BIT) & 1;

		/* no locking: HCD (i.e., we) own toggles, don't we? */
		usb_settoggle(old_dev, old_epnum, 0, rcvtog);
		usb_settoggle(old_dev, old_epnum, 1, sndtog);
	}
	/* setup new endpoint's toggle bits: */
	rcvtog = usb_gettoggle(dev, epnum, 0);
	sndtog = usb_gettoggle(dev, epnum, 1);
	hctl = (BIT(rcvtog + MAX3421_HCTL_RCVTOG0_BIT) |
		BIT(sndtog + MAX3421_HCTL_SNDTOG0_BIT));

	max3421_hcd->loaded_epnum = epnum;
	spi_wr8(hcd, MAX3421_REG_HCTL, hctl);

	/*
	 * Note: devnum for one and the same device can change during
	 * address-assignment so it's best to just always load the
	 * address whenever the end-point changed/was forced.
	 */
	max3421_hcd->loaded_dev = dev;
	spi_wr8(hcd, MAX3421_REG_PERADDR, dev->devnum);
}

static int
max3421_ctrl_setup(struct usb_hcd *hcd, struct urb *urb)
{
	spi_wr_buf(hcd, MAX3421_REG_SUDFIFO, urb->setup_packet, 8);
	return MAX3421_HXFR_SETUP;
}

static int
max3421_transfer_in(struct usb_hcd *hcd, struct urb *urb)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	int epnum = usb_pipeendpoint(urb->pipe);

	max3421_hcd->curr_len = 0;
	max3421_hcd->hien |= BIT(MAX3421_HI_RCVDAV_BIT);
	return MAX3421_HXFR_BULK_IN(epnum);
}

static int
max3421_transfer_out(struct usb_hcd *hcd, struct urb *urb, int fast_retransmit)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	int epnum = usb_pipeendpoint(urb->pipe);
	u32 max_packet;
	void *src;

	src = urb->transfer_buffer + urb->actual_length;

	if (fast_retransmit) {
		if (max3421_hcd->rev == 0x12) {
			/* work around rev 0x12 bug: */
			spi_wr8(hcd, MAX3421_REG_SNDBC, 0);
			spi_wr8(hcd, MAX3421_REG_SNDFIFO, ((u8 *) src)[0]);
			spi_wr8(hcd, MAX3421_REG_SNDBC, max3421_hcd->curr_len);
		}
		return MAX3421_HXFR_BULK_OUT(epnum);
	}

	max_packet = usb_maxpacket(urb->dev, urb->pipe, 1);

	if (max_packet > MAX3421_FIFO_SIZE) {
		/*
		 * We do not support isochronous transfers at this
		 * time.
		 */
		dev_err(&spi->dev,
			"%s: packet-size of %u too big (limit is %u bytes)",
			__func__, max_packet, MAX3421_FIFO_SIZE);
		max3421_hcd->urb_done = -EMSGSIZE;
		return -EMSGSIZE;
	}
	max3421_hcd->curr_len = min((urb->transfer_buffer_length -
				     urb->actual_length), max_packet);

	spi_wr_buf(hcd, MAX3421_REG_SNDFIFO, src, max3421_hcd->curr_len);
	spi_wr8(hcd, MAX3421_REG_SNDBC, max3421_hcd->curr_len);
	return MAX3421_HXFR_BULK_OUT(epnum);
}

/*
 * Issue the next host-transfer command.
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_next_transfer(struct usb_hcd *hcd, int fast_retransmit)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct urb *urb = max3421_hcd->curr_urb;
	struct max3421_ep *max3421_ep;
	int cmd = -EINVAL;

	if (!urb)
		return;	/* nothing to do */

	max3421_ep = urb->ep->hcpriv;

	switch (max3421_ep->pkt_state) {
	case PKT_STATE_SETUP:
		cmd = max3421_ctrl_setup(hcd, urb);
		break;

	case PKT_STATE_TRANSFER:
		if (usb_urb_dir_in(urb))
			cmd = max3421_transfer_in(hcd, urb);
		else
			cmd = max3421_transfer_out(hcd, urb, fast_retransmit);
		break;

	case PKT_STATE_TERMINATE:
		/*
		 * IN transfers are terminated with HS_OUT token,
		 * OUT transfers with HS_IN:
		 */
		if (usb_urb_dir_in(urb))
			cmd = MAX3421_HXFR_HS_OUT;
		else
			cmd = MAX3421_HXFR_HS_IN;
		break;
	}

	if (cmd < 0)
		return;

	/* issue the command and wait for host-xfer-done interrupt: */

	spi_wr8(hcd, MAX3421_REG_HXFR, cmd);
	max3421_hcd->hien |= BIT(MAX3421_HI_HXFRDN_BIT);
}

/*
 * Find the next URB to process and start its execution.
 *
 * At this time, we do not anticipate ever connecting a USB hub to the
 * MAX3421 chip, so at most USB device can be connected and we can use
 * a simplistic scheduler: at the start of a frame, schedule all
 * periodic transfers.  Once that is done, use the remainder of the
 * frame to process non-periodic (bulk & control) transfers.
 *
 * Preconditions:
 * o Caller must NOT hold HCD spinlock.
 * o max3421_hcd->curr_urb MUST BE NULL.
 * o MAX3421E chip must be idle.
 */
static int
max3421_select_and_start_urb(struct usb_hcd *hcd)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct urb *urb, *curr_urb = NULL;
	struct max3421_ep *max3421_ep;
	int epnum, force_toggles = 0;
	struct usb_host_endpoint *ep;
	struct list_head *pos;
	unsigned long flags;

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	for (;
	     max3421_hcd->sched_pass < SCHED_PASS_DONE;
	     ++max3421_hcd->sched_pass)
		list_for_each(pos, &max3421_hcd->ep_list) {
			urb = NULL;
			max3421_ep = container_of(pos, struct max3421_ep,
						  ep_list);
			ep = max3421_ep->ep;

			switch (usb_endpoint_type(&ep->desc)) {
			case USB_ENDPOINT_XFER_ISOC:
			case USB_ENDPOINT_XFER_INT:
				if (max3421_hcd->sched_pass !=
				    SCHED_PASS_PERIODIC)
					continue;
				break;

			case USB_ENDPOINT_XFER_CONTROL:
			case USB_ENDPOINT_XFER_BULK:
				if (max3421_hcd->sched_pass !=
				    SCHED_PASS_NON_PERIODIC)
					continue;
				break;
			}

			if (list_empty(&ep->urb_list))
				continue;	/* nothing to do */
			urb = list_first_entry(&ep->urb_list, struct urb,
					       urb_list);
			if (urb->unlinked) {
				dev_dbg(&spi->dev, "%s: URB %p unlinked=%d",
					__func__, urb, urb->unlinked);
				max3421_hcd->curr_urb = urb;
				max3421_hcd->urb_done = 1;
				spin_unlock_irqrestore(&max3421_hcd->lock,
						       flags);
				return 1;
			}

			switch (usb_endpoint_type(&ep->desc)) {
			case USB_ENDPOINT_XFER_CONTROL:
				/*
				 * Allow one control transaction per
				 * frame per endpoint:
				 */
				if (frame_diff(max3421_ep->last_active,
					       max3421_hcd->frame_number) == 0)
					continue;
				break;

			case USB_ENDPOINT_XFER_BULK:
				if (max3421_ep->retransmit
				    && (frame_diff(max3421_ep->last_active,
						   max3421_hcd->frame_number)
					== 0))
					/*
					 * We already tried this EP
					 * during this frame and got a
					 * NAK or error; wait for next frame
					 */
					continue;
				break;

			case USB_ENDPOINT_XFER_ISOC:
			case USB_ENDPOINT_XFER_INT:
				if (frame_diff(max3421_hcd->frame_number,
					       max3421_ep->last_active)
				    < urb->interval)
					/*
					 * We already processed this
					 * end-point in the current
					 * frame
					 */
					continue;
				break;
			}

			/* move current ep to tail: */
			list_move_tail(pos, &max3421_hcd->ep_list);
			curr_urb = urb;
			goto done;
		}
done:
	if (!curr_urb) {
		spin_unlock_irqrestore(&max3421_hcd->lock, flags);
		return 0;
	}

	urb = max3421_hcd->curr_urb = curr_urb;
	epnum = usb_endpoint_num(&urb->ep->desc);
	if (max3421_ep->retransmit)
		/* restart (part of) a USB transaction: */
		max3421_ep->retransmit = 0;
	else {
		/* start USB transaction: */
		if (usb_endpoint_xfer_control(&ep->desc)) {
			/*
			 * See USB 2.0 spec section 8.6.1
			 * Initialization via SETUP Token:
			 */
			usb_settoggle(urb->dev, epnum, 0, 1);
			usb_settoggle(urb->dev, epnum, 1, 1);
			max3421_ep->pkt_state = PKT_STATE_SETUP;
			force_toggles = 1;
		} else
			max3421_ep->pkt_state = PKT_STATE_TRANSFER;
	}

	spin_unlock_irqrestore(&max3421_hcd->lock, flags);

	max3421_ep->last_active = max3421_hcd->frame_number;
	max3421_set_address(hcd, urb->dev, epnum, force_toggles);
	max3421_set_speed(hcd, urb->dev);
	max3421_next_transfer(hcd, 0);
	return 1;
}

/*
 * Check all endpoints for URBs that got unlinked.
 *
 * Caller must NOT hold HCD spinlock.
 */
static int
max3421_check_unlink(struct usb_hcd *hcd)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct max3421_ep *max3421_ep;
	struct usb_host_endpoint *ep;
	struct urb *urb, *next;
	unsigned long flags;
	int retval = 0;

	spin_lock_irqsave(&max3421_hcd->lock, flags);
	list_for_each_entry(max3421_ep, &max3421_hcd->ep_list, ep_list) {
		ep = max3421_ep->ep;
		list_for_each_entry_safe(urb, next, &ep->urb_list, urb_list) {
			if (urb->unlinked) {
				retval = 1;
				dev_dbg(&spi->dev, "%s: URB %p unlinked=%d",
					__func__, urb, urb->unlinked);
				usb_hcd_unlink_urb_from_ep(hcd, urb);
				spin_unlock_irqrestore(&max3421_hcd->lock,
						       flags);
				usb_hcd_giveback_urb(hcd, urb, 0);
				spin_lock_irqsave(&max3421_hcd->lock, flags);
			}
		}
	}
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
	return retval;
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_slow_retransmit(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct urb *urb = max3421_hcd->curr_urb;
	struct max3421_ep *max3421_ep;

	max3421_ep = urb->ep->hcpriv;
	max3421_ep->retransmit = 1;
	max3421_hcd->curr_urb = NULL;
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_recv_data_available(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct urb *urb = max3421_hcd->curr_urb;
	size_t remaining, transfer_size;
	u8 rcvbc;

	rcvbc = spi_rd8(hcd, MAX3421_REG_RCVBC);

	if (rcvbc > MAX3421_FIFO_SIZE)
		rcvbc = MAX3421_FIFO_SIZE;
	if (urb->actual_length >= urb->transfer_buffer_length)
		remaining = 0;
	else
		remaining = urb->transfer_buffer_length - urb->actual_length;
	transfer_size = rcvbc;
	if (transfer_size > remaining)
		transfer_size = remaining;
	if (transfer_size > 0) {
		void *dst = urb->transfer_buffer + urb->actual_length;

		spi_rd_buf(hcd, MAX3421_REG_RCVFIFO, dst, transfer_size);
		urb->actual_length += transfer_size;
		max3421_hcd->curr_len = transfer_size;
	}

	/* ack the RCVDAV irq now that the FIFO has been read: */
	spi_wr8(hcd, MAX3421_REG_HIRQ, BIT(MAX3421_HI_RCVDAV_BIT));
}

static void
max3421_handle_error(struct usb_hcd *hcd, u8 hrsl)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	u8 result_code = hrsl & MAX3421_HRSL_RESULT_MASK;
	struct urb *urb = max3421_hcd->curr_urb;
	struct max3421_ep *max3421_ep = urb->ep->hcpriv;
	int switch_sndfifo;

	/*
	 * If an OUT command results in any response other than OK
	 * (i.e., error or NAK), we have to perform a dummy-write to
	 * SNDBC so the FIFO gets switched back to us.  Otherwise, we
	 * get out of sync with the SNDFIFO double buffer.
	 */
	switch_sndfifo = (max3421_ep->pkt_state == PKT_STATE_TRANSFER &&
			  usb_urb_dir_out(urb));

	switch (result_code) {
	case MAX3421_HRSL_OK:
		return;			/* this shouldn't happen */

	case MAX3421_HRSL_WRONGPID:	/* received wrong PID */
	case MAX3421_HRSL_BUSY:		/* SIE busy */
	case MAX3421_HRSL_BADREQ:	/* bad val in HXFR */
	case MAX3421_HRSL_UNDEF:	/* reserved */
	case MAX3421_HRSL_KERR:		/* K-state instead of response */
	case MAX3421_HRSL_JERR:		/* J-state instead of response */
		/*
		 * packet experienced an error that we cannot recover
		 * from; report error
		 */
		max3421_hcd->urb_done = hrsl_to_error[result_code];
		dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
			__func__, hrsl);
		break;

	case MAX3421_HRSL_TOGERR:
		if (usb_urb_dir_in(urb))
			; /* don't do anything (device will switch toggle) */
		else {
			/* flip the send toggle bit: */
			int sndtog = (hrsl >> MAX3421_HRSL_SNDTOGRD_BIT) & 1;

			sndtog ^= 1;
			spi_wr8(hcd, MAX3421_REG_HCTL,
				BIT(sndtog + MAX3421_HCTL_SNDTOG0_BIT));
		}
		fallthrough;
	case MAX3421_HRSL_BADBC:	/* bad byte count */
	case MAX3421_HRSL_PIDERR:	/* received PID is corrupted */
	case MAX3421_HRSL_PKTERR:	/* packet error (stuff, EOP) */
	case MAX3421_HRSL_CRCERR:	/* CRC error */
	case MAX3421_HRSL_BABBLE:	/* device talked too long */
	case MAX3421_HRSL_TIMEOUT:
		if (max3421_ep->retries++ < USB_MAX_RETRIES)
			/* retry the packet again in the next frame */
			max3421_slow_retransmit(hcd);
		else {
			/* Based on ohci.h cc_to_err[]: */
			max3421_hcd->urb_done = hrsl_to_error[result_code];
			dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
				__func__, hrsl);
		}
		break;

	case MAX3421_HRSL_STALL:
		dev_dbg(&spi->dev, "%s: unexpected error HRSL=0x%02x",
			__func__, hrsl);
		max3421_hcd->urb_done = hrsl_to_error[result_code];
		break;

	case MAX3421_HRSL_NAK:
		/*
		 * Device wasn't ready for data or has no data
		 * available: retry the packet again.
		 */
		if (max3421_ep->naks++ < NAK_MAX_FAST_RETRANSMITS) {
			max3421_next_transfer(hcd, 1);
			switch_sndfifo = 0;
		} else
			max3421_slow_retransmit(hcd);
		break;
	}
	if (switch_sndfifo)
		spi_wr8(hcd, MAX3421_REG_SNDBC, 0);
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static int
max3421_transfer_in_done(struct usb_hcd *hcd, struct urb *urb)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	u32 max_packet;

	if (urb->actual_length >= urb->transfer_buffer_length)
		return 1;	/* read is complete, so we're done */

	/*
	 * USB 2.0 Section 5.3.2 Pipes: packets must be full size
	 * except for last one.
	 */
	max_packet = usb_maxpacket(urb->dev, urb->pipe, 0);
	if (max_packet > MAX3421_FIFO_SIZE) {
		/*
		 * We do not support isochronous transfers at this
		 * time...
		 */
		dev_err(&spi->dev,
			"%s: packet-size of %u too big (limit is %u bytes)",
			__func__, max_packet, MAX3421_FIFO_SIZE);
		return -EINVAL;
	}

	if (max3421_hcd->curr_len < max_packet) {
		if (urb->transfer_flags & URB_SHORT_NOT_OK) {
			/*
			 * remaining > 0 and received an
			 * unexpected partial packet ->
			 * error
			 */
			return -EREMOTEIO;
		} else
			/* short read, but it's OK */
			return 1;
	}
	return 0;	/* not done */
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static int
max3421_transfer_out_done(struct usb_hcd *hcd, struct urb *urb)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);

	urb->actual_length += max3421_hcd->curr_len;
	if (urb->actual_length < urb->transfer_buffer_length)
		return 0;
	if (urb->transfer_flags & URB_ZERO_PACKET) {
		/*
		 * Some hardware needs a zero-size packet at the end
		 * of a bulk-out transfer if the last transfer was a
		 * full-sized packet (i.e., such hardware use <
		 * max_packet as an indicator that the end of the
		 * packet has been reached).
		 */
		u32 max_packet = usb_maxpacket(urb->dev, urb->pipe, 1);

		if (max3421_hcd->curr_len == max_packet)
			return 0;
	}
	return 1;
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_host_transfer_done(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct urb *urb = max3421_hcd->curr_urb;
	struct max3421_ep *max3421_ep;
	u8 result_code, hrsl;
	int urb_done = 0;

	max3421_hcd->hien &= ~(BIT(MAX3421_HI_HXFRDN_BIT) |
			       BIT(MAX3421_HI_RCVDAV_BIT));

	hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);
	result_code = hrsl & MAX3421_HRSL_RESULT_MASK;

#ifdef DEBUG
	++max3421_hcd->err_stat[result_code];
#endif

	max3421_ep = urb->ep->hcpriv;

	if (unlikely(result_code != MAX3421_HRSL_OK)) {
		max3421_handle_error(hcd, hrsl);
		return;
	}

	max3421_ep->naks = 0;
	max3421_ep->retries = 0;
	switch (max3421_ep->pkt_state) {

	case PKT_STATE_SETUP:
		if (urb->transfer_buffer_length > 0)
			max3421_ep->pkt_state = PKT_STATE_TRANSFER;
		else
			max3421_ep->pkt_state = PKT_STATE_TERMINATE;
		break;

	case PKT_STATE_TRANSFER:
		if (usb_urb_dir_in(urb))
			urb_done = max3421_transfer_in_done(hcd, urb);
		else
			urb_done = max3421_transfer_out_done(hcd, urb);
		if (urb_done > 0 && usb_pipetype(urb->pipe) == PIPE_CONTROL) {
			/*
			 * We aren't really done - we still need to
			 * terminate the control transfer:
			 */
			max3421_hcd->urb_done = urb_done = 0;
			max3421_ep->pkt_state = PKT_STATE_TERMINATE;
		}
		break;

	case PKT_STATE_TERMINATE:
		urb_done = 1;
		break;
	}

	if (urb_done)
		max3421_hcd->urb_done = urb_done;
	else
		max3421_next_transfer(hcd, 0);
}

/*
 * Caller must NOT hold HCD spinlock.
 */
static void
max3421_detect_conn(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	unsigned int jk, have_conn = 0;
	u32 old_port_status, chg;
	unsigned long flags;
	u8 hrsl, mode;

	hrsl = spi_rd8(hcd, MAX3421_REG_HRSL);

	jk = ((((hrsl >> MAX3421_HRSL_JSTATUS_BIT) & 1) << 0) |
	      (((hrsl >> MAX3421_HRSL_KSTATUS_BIT) & 1) << 1));

	mode = max3421_hcd->mode;

	switch (jk) {
	case 0x0: /* SE0: disconnect */
		/*
		 * Turn off SOFKAENAB bit to avoid getting interrupt
		 * every milli-second:
		 */
		mode &= ~BIT(MAX3421_MODE_SOFKAENAB_BIT);
		break;

	case 0x1: /* J=0,K=1: low-speed (in full-speed or vice versa) */
	case 0x2: /* J=1,K=0: full-speed (in full-speed or vice versa) */
		if (jk == 0x2)
			/* need to switch to the other speed: */
			mode ^= BIT(MAX3421_MODE_LOWSPEED_BIT);
		/* turn on SOFKAENAB bit: */
		mode |= BIT(MAX3421_MODE_SOFKAENAB_BIT);
		have_conn = 1;
		break;

	case 0x3: /* illegal */
		break;
	}

	max3421_hcd->mode = mode;
	spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);

	spin_lock_irqsave(&max3421_hcd->lock, flags);
	old_port_status = max3421_hcd->port_status;
	if (have_conn)
		max3421_hcd->port_status |=  USB_PORT_STAT_CONNECTION;
	else
		max3421_hcd->port_status &= ~USB_PORT_STAT_CONNECTION;
	if (mode & BIT(MAX3421_MODE_LOWSPEED_BIT))
		max3421_hcd->port_status |=  USB_PORT_STAT_LOW_SPEED;
	else
		max3421_hcd->port_status &= ~USB_PORT_STAT_LOW_SPEED;
	chg = (old_port_status ^ max3421_hcd->port_status);
	max3421_hcd->port_status |= chg << 16;
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
}

static irqreturn_t
max3421_irq_handler(int irq, void *dev_id)
{
	struct usb_hcd *hcd = dev_id;
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);

	if (max3421_hcd->spi_thread)
		wake_up_process(max3421_hcd->spi_thread);
	if (!test_and_set_bit(ENABLE_IRQ, &max3421_hcd->todo))
		disable_irq_nosync(spi->irq);
	return IRQ_HANDLED;
}

#ifdef DEBUG

static void
dump_eps(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct max3421_ep *max3421_ep;
	struct usb_host_endpoint *ep;
	char ubuf[512], *dp, *end;
	unsigned long flags;
	struct urb *urb;
	int epnum, ret;

	spin_lock_irqsave(&max3421_hcd->lock, flags);
	list_for_each_entry(max3421_ep, &max3421_hcd->ep_list, ep_list) {
		ep = max3421_ep->ep;

		dp = ubuf;
		end = dp + sizeof(ubuf);
		*dp = '\0';
		list_for_each_entry(urb, &ep->urb_list, urb_list) {
			ret = snprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb,
				       usb_pipetype(urb->pipe),
				       usb_urb_dir_in(urb) ? "IN" : "OUT",
				       urb->actual_length,
				       urb->transfer_buffer_length);
			if (ret < 0 || ret >= end - dp)
				break;	/* error or buffer full */
			dp += ret;
		}

		epnum = usb_endpoint_num(&ep->desc);
		pr_info("EP%0u %u lst %04u rtr %u nak %6u rxmt %u: %s\n",
			epnum, max3421_ep->pkt_state, max3421_ep->last_active,
			max3421_ep->retries, max3421_ep->naks,
			max3421_ep->retransmit, ubuf);
	}
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
}

#endif /* DEBUG */

/* Return zero if no work was performed, 1 otherwise.  */
static int
max3421_handle_irqs(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	u32 chg, old_port_status;
	unsigned long flags;
	u8 hirq;

	/*
	 * Read and ack pending interrupts (CPU must never
	 * clear SNDBAV directly and RCVDAV must be cleared by
	 * max3421_recv_data_available()!):
	 */
	hirq = spi_rd8(hcd, MAX3421_REG_HIRQ);
	hirq &= max3421_hcd->hien;
	if (!hirq)
		return 0;

	spi_wr8(hcd, MAX3421_REG_HIRQ,
		hirq & ~(BIT(MAX3421_HI_SNDBAV_BIT) |
			 BIT(MAX3421_HI_RCVDAV_BIT)));

	if (hirq & BIT(MAX3421_HI_FRAME_BIT)) {
		max3421_hcd->frame_number = ((max3421_hcd->frame_number + 1)
					     & USB_MAX_FRAME_NUMBER);
		max3421_hcd->sched_pass = SCHED_PASS_PERIODIC;
	}

	if (hirq & BIT(MAX3421_HI_RCVDAV_BIT))
		max3421_recv_data_available(hcd);

	if (hirq & BIT(MAX3421_HI_HXFRDN_BIT))
		max3421_host_transfer_done(hcd);

	if (hirq & BIT(MAX3421_HI_CONDET_BIT))
		max3421_detect_conn(hcd);

	/*
	 * Now process interrupts that may affect HCD state
	 * other than the end-points:
	 */
	spin_lock_irqsave(&max3421_hcd->lock, flags);

	old_port_status = max3421_hcd->port_status;
	if (hirq & BIT(MAX3421_HI_BUSEVENT_BIT)) {
		if (max3421_hcd->port_status & USB_PORT_STAT_RESET) {
			/* BUSEVENT due to completion of Bus Reset */
			max3421_hcd->port_status &= ~USB_PORT_STAT_RESET;
			max3421_hcd->port_status |=  USB_PORT_STAT_ENABLE;
		} else {
			/* BUSEVENT due to completion of Bus Resume */
			pr_info("%s: BUSEVENT Bus Resume Done\n", __func__);
		}
	}
	if (hirq & BIT(MAX3421_HI_RWU_BIT))
		pr_info("%s: RWU\n", __func__);
	if (hirq & BIT(MAX3421_HI_SUSDN_BIT))
		pr_info("%s: SUSDN\n", __func__);

	chg = (old_port_status ^ max3421_hcd->port_status);
	max3421_hcd->port_status |= chg << 16;

	spin_unlock_irqrestore(&max3421_hcd->lock, flags);

#ifdef DEBUG
	{
		static unsigned long last_time;
		char sbuf[16 * 16], *dp, *end;
		int i;

		if (time_after(jiffies, last_time + 5*HZ)) {
			dp = sbuf;
			end = sbuf + sizeof(sbuf);
			*dp = '\0';
			for (i = 0; i < 16; ++i) {
				int ret = snprintf(dp, end - dp, " %lu",
						   max3421_hcd->err_stat[i]);
				if (ret < 0 || ret >= end - dp)
					break;	/* error or buffer full */
				dp += ret;
			}
			pr_info("%s: hrsl_stats %s\n", __func__, sbuf);
			memset(max3421_hcd->err_stat, 0,
			       sizeof(max3421_hcd->err_stat));
			last_time = jiffies;

			dump_eps(hcd);
		}
	}
#endif
	return 1;
}

static int
max3421_reset_hcd(struct usb_hcd *hcd)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	int timeout;

	/* perform a chip reset and wait for OSCIRQ signal to appear: */
	spi_wr8(hcd, MAX3421_REG_USBCTL, BIT(MAX3421_USBCTL_CHIPRES_BIT));
	/* clear reset: */
	spi_wr8(hcd, MAX3421_REG_USBCTL, 0);
	timeout = 1000;
	while (1) {
		if (spi_rd8(hcd, MAX3421_REG_USBIRQ)
		    & BIT(MAX3421_USBIRQ_OSCOKIRQ_BIT))
			break;
		if (--timeout < 0) {
			dev_err(&spi->dev,
				"timed out waiting for oscillator OK signal");
			return 1;
		}
		cond_resched();
	}

	/*
	 * Turn on host mode, automatic generation of SOF packets, and
	 * enable pull-down registers on DM/DP:
	 */
	max3421_hcd->mode = (BIT(MAX3421_MODE_HOST_BIT) |
			     BIT(MAX3421_MODE_SOFKAENAB_BIT) |
			     BIT(MAX3421_MODE_DMPULLDN_BIT) |
			     BIT(MAX3421_MODE_DPPULLDN_BIT));
	spi_wr8(hcd, MAX3421_REG_MODE, max3421_hcd->mode);

	/* reset frame-number: */
	max3421_hcd->frame_number = USB_MAX_FRAME_NUMBER;
	spi_wr8(hcd, MAX3421_REG_HCTL, BIT(MAX3421_HCTL_FRMRST_BIT));

	/* sample the state of the D+ and D- lines */
	spi_wr8(hcd, MAX3421_REG_HCTL, BIT(MAX3421_HCTL_SAMPLEBUS_BIT));
	max3421_detect_conn(hcd);

	/* enable frame, connection-detected, and bus-event interrupts: */
	max3421_hcd->hien = (BIT(MAX3421_HI_FRAME_BIT) |
			     BIT(MAX3421_HI_CONDET_BIT) |
			     BIT(MAX3421_HI_BUSEVENT_BIT));
	spi_wr8(hcd, MAX3421_REG_HIEN, max3421_hcd->hien);

	/* enable interrupts: */
	spi_wr8(hcd, MAX3421_REG_CPUCTL, BIT(MAX3421_CPUCTL_IE_BIT));
	return 1;
}

static int
max3421_urb_done(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	unsigned long flags;
	struct urb *urb;
	int status;

	status = max3421_hcd->urb_done;
	max3421_hcd->urb_done = 0;
	if (status > 0)
		status = 0;
	urb = max3421_hcd->curr_urb;
	if (urb) {
		max3421_hcd->curr_urb = NULL;
		spin_lock_irqsave(&max3421_hcd->lock, flags);
		usb_hcd_unlink_urb_from_ep(hcd, urb);
		spin_unlock_irqrestore(&max3421_hcd->lock, flags);

		/* must be called without the HCD spinlock: */
		usb_hcd_giveback_urb(hcd, urb, status);
	}
	return 1;
}

static int
max3421_spi_thread(void *dev_id)
{
	struct usb_hcd *hcd = dev_id;
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	int i, i_worked = 1;

	/* set full-duplex SPI mode, low-active interrupt pin: */
	spi_wr8(hcd, MAX3421_REG_PINCTL,
		(BIT(MAX3421_PINCTL_FDUPSPI_BIT) |	/* full-duplex */
		 BIT(MAX3421_PINCTL_INTLEVEL_BIT)));	/* low-active irq */

	while (!kthread_should_stop()) {
		max3421_hcd->rev = spi_rd8(hcd, MAX3421_REG_REVISION);
		if (max3421_hcd->rev == 0x12 || max3421_hcd->rev == 0x13)
			break;
		dev_err(&spi->dev, "bad rev 0x%02x", max3421_hcd->rev);
		msleep(10000);
	}
	dev_info(&spi->dev, "rev 0x%x, SPI clk %dHz, bpw %u, irq %d\n",
		 max3421_hcd->rev, spi->max_speed_hz, spi->bits_per_word,
		 spi->irq);

	while (!kthread_should_stop()) {
		if (!i_worked) {
			/*
			 * We'll be waiting for wakeups from the hard
			 * interrupt handler, so now is a good time to
			 * sync our hien with the chip:
			 */
			spi_wr8(hcd, MAX3421_REG_HIEN, max3421_hcd->hien);

			set_current_state(TASK_INTERRUPTIBLE);
			if (test_and_clear_bit(ENABLE_IRQ, &max3421_hcd->todo))
				enable_irq(spi->irq);
			schedule();
			__set_current_state(TASK_RUNNING);
		}

		i_worked = 0;

		if (max3421_hcd->urb_done)
			i_worked |= max3421_urb_done(hcd);
		else if (max3421_handle_irqs(hcd))
			i_worked = 1;
		else if (!max3421_hcd->curr_urb)
			i_worked |= max3421_select_and_start_urb(hcd);

		if (test_and_clear_bit(RESET_HCD, &max3421_hcd->todo))
			/* reset the HCD: */
			i_worked |= max3421_reset_hcd(hcd);
		if (test_and_clear_bit(RESET_PORT, &max3421_hcd->todo)) {
			/* perform a USB bus reset: */
			spi_wr8(hcd, MAX3421_REG_HCTL,
				BIT(MAX3421_HCTL_BUSRST_BIT));
			i_worked = 1;
		}
		if (test_and_clear_bit(CHECK_UNLINK, &max3421_hcd->todo))
			i_worked |= max3421_check_unlink(hcd);
		if (test_and_clear_bit(IOPIN_UPDATE, &max3421_hcd->todo)) {
			/*
			 * IOPINS1/IOPINS2 do not auto-increment, so we can't
			 * use spi_wr_buf().
			 */
			for (i = 0; i < ARRAY_SIZE(max3421_hcd->iopins); ++i) {
				u8 val = spi_rd8(hcd, MAX3421_REG_IOPINS1);

				val = ((val & 0xf0) |
				       (max3421_hcd->iopins[i] & 0x0f));
				spi_wr8(hcd, MAX3421_REG_IOPINS1 + i, val);
				max3421_hcd->iopins[i] = val;
			}
			i_worked = 1;
		}
	}
	set_current_state(TASK_RUNNING);
	dev_info(&spi->dev, "SPI thread exiting");
	return 0;
}

static int
max3421_reset_port(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);

	max3421_hcd->port_status &= ~(USB_PORT_STAT_ENABLE |
				      USB_PORT_STAT_LOW_SPEED);
	max3421_hcd->port_status |= USB_PORT_STAT_RESET;
	set_bit(RESET_PORT, &max3421_hcd->todo);
	wake_up_process(max3421_hcd->spi_thread);
	return 0;
}

static int
max3421_reset(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);

	hcd->self.sg_tablesize = 0;
	hcd->speed = HCD_USB2;
	hcd->self.root_hub->speed = USB_SPEED_FULL;
	set_bit(RESET_HCD, &max3421_hcd->todo);
	wake_up_process(max3421_hcd->spi_thread);
	return 0;
}

static int
max3421_start(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);

	spin_lock_init(&max3421_hcd->lock);
	max3421_hcd->rh_state = MAX3421_RH_RUNNING;

	INIT_LIST_HEAD(&max3421_hcd->ep_list);

	hcd->power_budget = POWER_BUDGET;
	hcd->state = HC_STATE_RUNNING;
	hcd->uses_new_polling = 1;
	return 0;
}

static void
max3421_stop(struct usb_hcd *hcd)
{
}

static int
max3421_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct max3421_ep *max3421_ep;
	unsigned long flags;
	int retval;

	switch (usb_pipetype(urb->pipe)) {
	case PIPE_INTERRUPT:
	case PIPE_ISOCHRONOUS:
		if (urb->interval < 0) {
			dev_err(&spi->dev,
			  "%s: interval=%d for intr-/iso-pipe; expected > 0\n",
				__func__, urb->interval);
			return -EINVAL;
		}
		break;
	default:
		break;
	}

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	max3421_ep = urb->ep->hcpriv;
	if (!max3421_ep) {
		/* gets freed in max3421_endpoint_disable: */
		max3421_ep = kzalloc(sizeof(struct max3421_ep), GFP_ATOMIC);
		if (!max3421_ep) {
			retval = -ENOMEM;
			goto out;
		}
		max3421_ep->ep = urb->ep;
		max3421_ep->last_active = max3421_hcd->frame_number;
		urb->ep->hcpriv = max3421_ep;

		list_add_tail(&max3421_ep->ep_list, &max3421_hcd->ep_list);
	}

	retval = usb_hcd_link_urb_to_ep(hcd, urb);
	if (retval == 0) {
		/* Since we added to the queue, restart scheduling: */
		max3421_hcd->sched_pass = SCHED_PASS_PERIODIC;
		wake_up_process(max3421_hcd->spi_thread);
	}

out:
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
	return retval;
}

static int
max3421_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	unsigned long flags;
	int retval;

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	/*
	 * This will set urb->unlinked which in turn causes the entry
	 * to be dropped at the next opportunity.
	 */
	retval = usb_hcd_check_unlink_urb(hcd, urb, status);
	if (retval == 0) {
		set_bit(CHECK_UNLINK, &max3421_hcd->todo);
		wake_up_process(max3421_hcd->spi_thread);
	}
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
	return retval;
}

static void
max3421_endpoint_disable(struct usb_hcd *hcd, struct usb_host_endpoint *ep)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	unsigned long flags;

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	if (ep->hcpriv) {
		struct max3421_ep *max3421_ep = ep->hcpriv;

		/* remove myself from the ep_list: */
		if (!list_empty(&max3421_ep->ep_list))
			list_del(&max3421_ep->ep_list);
		kfree(max3421_ep);
		ep->hcpriv = NULL;
	}

	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
}

static int
max3421_get_frame_number(struct usb_hcd *hcd)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	return max3421_hcd->frame_number;
}

/*
 * Should return a non-zero value when any port is undergoing a resume
 * transition while the root hub is suspended.
 */
static int
max3421_hub_status_data(struct usb_hcd *hcd, char *buf)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	unsigned long flags;
	int retval = 0;

	spin_lock_irqsave(&max3421_hcd->lock, flags);
	if (!HCD_HW_ACCESSIBLE(hcd))
		goto done;

	*buf = 0;
	if ((max3421_hcd->port_status & PORT_C_MASK) != 0) {
		*buf = (1 << 1); /* a hub over-current condition exists */
		dev_dbg(hcd->self.controller,
			"port status 0x%08x has changes\n",
			max3421_hcd->port_status);
		retval = 1;
		if (max3421_hcd->rh_state == MAX3421_RH_SUSPENDED)
			usb_hcd_resume_root_hub(hcd);
	}
done:
	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
	return retval;
}

static inline void
hub_descriptor(struct usb_hub_descriptor *desc)
{
	memset(desc, 0, sizeof(*desc));
	/*
	 * See Table 11-13: Hub Descriptor in USB 2.0 spec.
	 */
	desc->bDescriptorType = USB_DT_HUB; /* hub descriptor */
	desc->bDescLength = 9;
	desc->wHubCharacteristics = cpu_to_le16(HUB_CHAR_INDV_PORT_LPSM |
						HUB_CHAR_COMMON_OCPM);
	desc->bNbrPorts = 1;
}

/*
 * Set the MAX3421E general-purpose output with number PIN_NUMBER to
 * VALUE (0 or 1).  PIN_NUMBER may be in the range from 1-8.  For
 * any other value, this function acts as a no-op.
 */
static void
max3421_gpout_set_value(struct usb_hcd *hcd, u8 pin_number, u8 value)
{
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	u8 mask, idx;

	--pin_number;
	if (pin_number >= MAX3421_GPOUT_COUNT)
		return;

	mask = 1u << (pin_number % 4);
	idx = pin_number / 4;

	if (value)
		max3421_hcd->iopins[idx] |=  mask;
	else
		max3421_hcd->iopins[idx] &= ~mask;
	set_bit(IOPIN_UPDATE, &max3421_hcd->todo);
	wake_up_process(max3421_hcd->spi_thread);
}

static int
max3421_hub_control(struct usb_hcd *hcd, u16 type_req, u16 value, u16 index,
		    char *buf, u16 length)
{
	struct spi_device *spi = to_spi_device(hcd->self.controller);
	struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
	struct max3421_hcd_platform_data *pdata;
	unsigned long flags;
	int retval = 0;

	pdata = spi->dev.platform_data;

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	switch (type_req) {
	case ClearHubFeature:
		break;
	case ClearPortFeature:
		switch (value) {
		case USB_PORT_FEAT_SUSPEND:
			break;
		case USB_PORT_FEAT_POWER:
			dev_dbg(hcd->self.controller, "power-off\n");
			max3421_gpout_set_value(hcd, pdata->vbus_gpout,
						!pdata->vbus_active_level);
			fallthrough;
		default:
			max3421_hcd->port_status &= ~(1 << value);
		}
		break;
	case GetHubDescriptor:
		hub_descriptor((struct usb_hub_descriptor *) buf);
		break;

	case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
	case GetPortErrorCount:
	case SetHubDepth:
		/* USB3 only */
		goto error;

	case GetHubStatus:
		*(__le32 *) buf = cpu_to_le32(0);
		break;

	case GetPortStatus:
		if (index != 1) {
			retval = -EPIPE;
			goto error;
		}
		((__le16 *) buf)[0] = cpu_to_le16(max3421_hcd->port_status);
		((__le16 *) buf)[1] =
			cpu_to_le16(max3421_hcd->port_status >> 16);
		break;

	case SetHubFeature:
		retval = -EPIPE;
		break;

	case SetPortFeature:
		switch (value) {
		case USB_PORT_FEAT_LINK_STATE:
		case USB_PORT_FEAT_U1_TIMEOUT:
		case USB_PORT_FEAT_U2_TIMEOUT:
		case USB_PORT_FEAT_BH_PORT_RESET:
			goto error;
		case USB_PORT_FEAT_SUSPEND:
			if (max3421_hcd->active)
				max3421_hcd->port_status |=
					USB_PORT_STAT_SUSPEND;
			break;
		case USB_PORT_FEAT_POWER:
			dev_dbg(hcd->self.controller, "power-on\n");
			max3421_hcd->port_status |= USB_PORT_STAT_POWER;
			max3421_gpout_set_value(hcd, pdata->vbus_gpout,
						pdata->vbus_active_level);
			break;
		case USB_PORT_FEAT_RESET:
			max3421_reset_port(hcd);
			fallthrough;
		default:
			if ((max3421_hcd->port_status & USB_PORT_STAT_POWER)
			    != 0)
				max3421_hcd->port_status |= (1 << value);
		}
		break;

	default:
		dev_dbg(hcd->self.controller,
			"hub control req%04x v%04x i%04x l%d\n",
			type_req, value, index, length);
error:		/* "protocol stall" on error */
		retval = -EPIPE;
	}

	spin_unlock_irqrestore(&max3421_hcd->lock, flags);
	return retval;
}

static int
max3421_bus_suspend(struct usb_hcd *hcd)
{
	return -1;
}

static int
max3421_bus_resume(struct usb_hcd *hcd)
{
	return -1;
}

static const struct hc_driver max3421_hcd_desc = {
	.description =		"max3421",
	.product_desc =		DRIVER_DESC,
	.hcd_priv_size =	sizeof(struct max3421_hcd),
	.flags =		HCD_USB11,
	.reset =		max3421_reset,
	.start =		max3421_start,
	.stop =			max3421_stop,
	.get_frame_number =	max3421_get_frame_number,
	.urb_enqueue =		max3421_urb_enqueue,
	.urb_dequeue =		max3421_urb_dequeue,
	.endpoint_disable =	max3421_endpoint_disable,
	.hub_status_data =	max3421_hub_status_data,
	.hub_control =		max3421_hub_control,
	.bus_suspend =		max3421_bus_suspend,
	.bus_resume =		max3421_bus_resume,
};

static int
max3421_of_vbus_en_pin(struct device *dev, struct max3421_hcd_platform_data *pdata)
{
	int retval;
	uint32_t value[2];

	if (!pdata)
		return -EINVAL;

	retval = of_property_read_u32_array(dev->of_node, "maxim,vbus-en-pin", value, 2);
	if (retval) {
		dev_err(dev, "device tree node property 'maxim,vbus-en-pin' is missing\n");
		return retval;
	}
	dev_info(dev, "property 'maxim,vbus-en-pin' value is <%d %d>\n", value[0], value[1]);

	pdata->vbus_gpout = value[0];
	pdata->vbus_active_level = value[1];

	return 0;
}

static int
max3421_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct max3421_hcd *max3421_hcd;
	struct usb_hcd *hcd = NULL;
	struct max3421_hcd_platform_data *pdata = NULL;
	int retval;

	if (spi_setup(spi) < 0) {
		dev_err(&spi->dev, "Unable to setup SPI bus");
		return -EFAULT;
	}

	if (!spi->irq) {
		dev_err(dev, "Failed to get SPI IRQ");
		return -EFAULT;
	}

	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
		pdata = devm_kzalloc(&spi->dev, sizeof(*pdata), GFP_KERNEL);
		if (!pdata) {
			retval = -ENOMEM;
			goto error;
		}
		retval = max3421_of_vbus_en_pin(dev, pdata);
		if (retval)
			goto error;

		spi->dev.platform_data = pdata;
	}

	pdata = spi->dev.platform_data;
	if (!pdata) {
		dev_err(&spi->dev, "driver configuration data is not provided\n");
		retval = -EFAULT;
		goto error;
	}
	if (pdata->vbus_active_level > 1) {
		dev_err(&spi->dev, "vbus active level value %d is out of range (0/1)\n", pdata->vbus_active_level);
		retval = -EINVAL;
		goto error;
	}
	if (pdata->vbus_gpout < 1 || pdata->vbus_gpout > MAX3421_GPOUT_COUNT) {
		dev_err(&spi->dev, "vbus gpout value %d is out of range (1..8)\n", pdata->vbus_gpout);
		retval = -EINVAL;
		goto error;
	}

	retval = -ENOMEM;
	hcd = usb_create_hcd(&max3421_hcd_desc, &spi->dev,
			     dev_name(&spi->dev));
	if (!hcd) {
		dev_err(&spi->dev, "failed to create HCD structure\n");
		goto error;
	}
	set_bit(HCD_FLAG_POLL_RH, &hcd->flags);
	max3421_hcd = hcd_to_max3421(hcd);
	max3421_hcd->next = max3421_hcd_list;
	max3421_hcd_list = max3421_hcd;
	INIT_LIST_HEAD(&max3421_hcd->ep_list);

	max3421_hcd->tx = kmalloc(sizeof(*max3421_hcd->tx), GFP_KERNEL);
	if (!max3421_hcd->tx)
		goto error;
	max3421_hcd->rx = kmalloc(sizeof(*max3421_hcd->rx), GFP_KERNEL);
	if (!max3421_hcd->rx)
		goto error;

	max3421_hcd->spi_thread = kthread_run(max3421_spi_thread, hcd,
					      "max3421_spi_thread");
	if (max3421_hcd->spi_thread == ERR_PTR(-ENOMEM)) {
		dev_err(&spi->dev,
			"failed to create SPI thread (out of memory)\n");
		goto error;
	}

	retval = usb_add_hcd(hcd, 0, 0);
	if (retval) {
		dev_err(&spi->dev, "failed to add HCD\n");
		goto error;
	}

	retval = request_irq(spi->irq, max3421_irq_handler,
			     IRQF_TRIGGER_LOW, "max3421", hcd);
	if (retval < 0) {
		dev_err(&spi->dev, "failed to request irq %d\n", spi->irq);
		goto error;
	}
	return 0;

error:
	if (IS_ENABLED(CONFIG_OF) && dev->of_node && pdata) {
		devm_kfree(&spi->dev, pdata);
		spi->dev.platform_data = NULL;
	}

	if (hcd) {
		kfree(max3421_hcd->tx);
		kfree(max3421_hcd->rx);
		if (max3421_hcd->spi_thread)
			kthread_stop(max3421_hcd->spi_thread);
		usb_put_hcd(hcd);
	}
	return retval;
}

static int
max3421_remove(struct spi_device *spi)
{
	struct max3421_hcd *max3421_hcd = NULL, **prev;
	struct usb_hcd *hcd = NULL;
	unsigned long flags;

	for (prev = &max3421_hcd_list; *prev; prev = &(*prev)->next) {
		max3421_hcd = *prev;
		hcd = max3421_to_hcd(max3421_hcd);
		if (hcd->self.controller == &spi->dev)
			break;
	}
	if (!max3421_hcd) {
		dev_err(&spi->dev, "no MAX3421 HCD found for SPI device %p\n",
			spi);
		return -ENODEV;
	}

	usb_remove_hcd(hcd);

	spin_lock_irqsave(&max3421_hcd->lock, flags);

	kthread_stop(max3421_hcd->spi_thread);
	*prev = max3421_hcd->next;

	spin_unlock_irqrestore(&max3421_hcd->lock, flags);

	free_irq(spi->irq, hcd);

	usb_put_hcd(hcd);
	return 0;
}

static const struct of_device_id max3421_of_match_table[] = {
	{ .compatible = "maxim,max3421", },
	{},
};
MODULE_DEVICE_TABLE(of, max3421_of_match_table);

static struct spi_driver max3421_driver = {
	.probe		= max3421_probe,
	.remove		= max3421_remove,
	.driver		= {
		.name	= "max3421-hcd",
		.of_match_table = of_match_ptr(max3421_of_match_table),
	},
};

module_spi_driver(max3421_driver);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("David Mosberger <davidm@egauge.net>");
MODULE_LICENSE("GPL");