aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/early/ehci-dbgp.c
blob: 5e29ddeb4d33d0c65f29116dca2ddbe42ea5407f (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
/*
 * Standalone EHCI usb debug driver
 *
 * Originally written by:
 *  Eric W. Biederman" <ebiederm@xmission.com> and
 *  Yinghai Lu <yhlu.kernel@gmail.com>
 *
 * Changes for early/late printk and HW errata:
 *  Jason Wessel <jason.wessel@windriver.com>
 *  Copyright (C) 2009 Wind River Systems, Inc.
 *
 */

#include <linux/console.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/pci_regs.h>
#include <linux/pci_ids.h>
#include <linux/usb/ch9.h>
#include <linux/usb/ehci_def.h>
#include <linux/delay.h>
#include <linux/serial_core.h>
#include <linux/kconfig.h>
#include <linux/kgdb.h>
#include <linux/kthread.h>
#include <asm/io.h>
#include <asm/pci-direct.h>
#include <asm/fixmap.h>

/* The code here is intended to talk directly to the EHCI debug port
 * and does not require that you have any kind of USB host controller
 * drivers or USB device drivers compiled into the kernel.
 *
 * If you make a change to anything in here, the following test cases
 * need to pass where a USB debug device works in the following
 * configurations.
 *
 * 1. boot args:  earlyprintk=dbgp
 *     o kernel compiled with # CONFIG_USB_EHCI_HCD is not set
 *     o kernel compiled with CONFIG_USB_EHCI_HCD=y
 * 2. boot args: earlyprintk=dbgp,keep
 *     o kernel compiled with # CONFIG_USB_EHCI_HCD is not set
 *     o kernel compiled with CONFIG_USB_EHCI_HCD=y
 * 3. boot args: earlyprintk=dbgp console=ttyUSB0
 *     o kernel has CONFIG_USB_EHCI_HCD=y and
 *       CONFIG_USB_SERIAL_DEBUG=y
 * 4. boot args: earlyprintk=vga,dbgp
 *     o kernel compiled with # CONFIG_USB_EHCI_HCD is not set
 *     o kernel compiled with CONFIG_USB_EHCI_HCD=y
 *
 * For the 4th configuration you can turn on or off the DBGP_DEBUG
 * such that you can debug the dbgp device's driver code.
 */

static int dbgp_phys_port = 1;

static struct ehci_caps __iomem *ehci_caps;
static struct ehci_regs __iomem *ehci_regs;
static struct ehci_dbg_port __iomem *ehci_debug;
static int dbgp_not_safe; /* Cannot use debug device during ehci reset */
static unsigned int dbgp_endpoint_out;
static unsigned int dbgp_endpoint_in;

struct ehci_dev {
	u32 bus;
	u32 slot;
	u32 func;
};

static struct ehci_dev ehci_dev;

#define USB_DEBUG_DEVNUM 127

#ifdef DBGP_DEBUG
#define dbgp_printk printk
static void dbgp_ehci_status(char *str)
{
	if (!ehci_debug)
		return;
	dbgp_printk("dbgp: %s\n", str);
	dbgp_printk("  Debug control: %08x", readl(&ehci_debug->control));
	dbgp_printk("  ehci cmd     : %08x", readl(&ehci_regs->command));
	dbgp_printk("  ehci conf flg: %08x\n",
		    readl(&ehci_regs->configured_flag));
	dbgp_printk("  ehci status  : %08x", readl(&ehci_regs->status));
	dbgp_printk("  ehci portsc  : %08x\n",
		    readl(&ehci_regs->port_status[dbgp_phys_port - 1]));
}
#else
static inline void dbgp_ehci_status(char *str) { }
static inline void dbgp_printk(const char *fmt, ...) { }
#endif

static inline u32 dbgp_len_update(u32 x, u32 len)
{
	return (x & ~0x0f) | (len & 0x0f);
}

#ifdef CONFIG_KGDB
static struct kgdb_io kgdbdbgp_io_ops;
#define dbgp_kgdb_mode (dbg_io_ops == &kgdbdbgp_io_ops)
#else
#define dbgp_kgdb_mode (0)
#endif

/* Local version of HC_LENGTH macro as ehci struct is not available here */
#define EARLY_HC_LENGTH(p)	(0x00ff & (p)) /* bits 7 : 0 */

/*
 * USB Packet IDs (PIDs)
 */

/* token */
#define USB_PID_OUT		0xe1
#define USB_PID_IN		0x69
#define USB_PID_SOF		0xa5
#define USB_PID_SETUP		0x2d
/* handshake */
#define USB_PID_ACK		0xd2
#define USB_PID_NAK		0x5a
#define USB_PID_STALL		0x1e
#define USB_PID_NYET		0x96
/* data */
#define USB_PID_DATA0		0xc3
#define USB_PID_DATA1		0x4b
#define USB_PID_DATA2		0x87
#define USB_PID_MDATA		0x0f
/* Special */
#define USB_PID_PREAMBLE	0x3c
#define USB_PID_ERR		0x3c
#define USB_PID_SPLIT		0x78
#define USB_PID_PING		0xb4
#define USB_PID_UNDEF_0		0xf0

#define USB_PID_DATA_TOGGLE	0x88
#define DBGP_CLAIM (DBGP_OWNER | DBGP_ENABLED | DBGP_INUSE)

#define PCI_CAP_ID_EHCI_DEBUG	0xa

#define HUB_ROOT_RESET_TIME	50	/* times are in msec */
#define HUB_SHORT_RESET_TIME	10
#define HUB_LONG_RESET_TIME	200
#define HUB_RESET_TIMEOUT	500

#define DBGP_MAX_PACKET		8
#define DBGP_TIMEOUT		(250 * 1000)
#define DBGP_LOOPS		1000

static inline u32 dbgp_pid_write_update(u32 x, u32 tok)
{
	static int data0 = USB_PID_DATA1;
	data0 ^= USB_PID_DATA_TOGGLE;
	return (x & 0xffff0000) | (data0 << 8) | (tok & 0xff);
}

static inline u32 dbgp_pid_read_update(u32 x, u32 tok)
{
	return (x & 0xffff0000) | (USB_PID_DATA0 << 8) | (tok & 0xff);
}

static int dbgp_wait_until_complete(void)
{
	u32 ctrl;
	int loop = DBGP_TIMEOUT;

	do {
		ctrl = readl(&ehci_debug->control);
		/* Stop when the transaction is finished */
		if (ctrl & DBGP_DONE)
			break;
		udelay(1);
	} while (--loop > 0);

	if (!loop)
		return -DBGP_TIMEOUT;

	/*
	 * Now that we have observed the completed transaction,
	 * clear the done bit.
	 */
	writel(ctrl | DBGP_DONE, &ehci_debug->control);
	return (ctrl & DBGP_ERROR) ? -DBGP_ERRCODE(ctrl) : DBGP_LEN(ctrl);
}

static inline void dbgp_mdelay(int ms)
{
	int i;

	while (ms--) {
		for (i = 0; i < 1000; i++)
			outb(0x1, 0x80);
	}
}

static void dbgp_breath(void)
{
	/* Sleep to give the debug port a chance to breathe */
}

static int dbgp_wait_until_done(unsigned ctrl, int loop)
{
	u32 pids, lpid;
	int ret;

retry:
	writel(ctrl | DBGP_GO, &ehci_debug->control);
	ret = dbgp_wait_until_complete();
	pids = readl(&ehci_debug->pids);
	lpid = DBGP_PID_GET(pids);

	if (ret < 0) {
		/* A -DBGP_TIMEOUT failure here means the device has
		 * failed, perhaps because it was unplugged, in which
		 * case we do not want to hang the system so the dbgp
		 * will be marked as unsafe to use.  EHCI reset is the
		 * only way to recover if you unplug the dbgp device.
		 */
		if (ret == -DBGP_TIMEOUT && !dbgp_not_safe)
			dbgp_not_safe = 1;
		if (ret == -DBGP_ERR_BAD && --loop > 0)
			goto retry;
		return ret;
	}

	/*
	 * If the port is getting full or it has dropped data
	 * start pacing ourselves, not necessary but it's friendly.
	 */
	if ((lpid == USB_PID_NAK) || (lpid == USB_PID_NYET))
		dbgp_breath();

	/* If I get a NACK reissue the transmission */
	if (lpid == USB_PID_NAK) {
		if (--loop > 0)
			goto retry;
	}

	return ret;
}

static inline void dbgp_set_data(const void *buf, int size)
{
	const unsigned char *bytes = buf;
	u32 lo, hi;
	int i;

	lo = hi = 0;
	for (i = 0; i < 4 && i < size; i++)
		lo |= bytes[i] << (8*i);
	for (; i < 8 && i < size; i++)
		hi |= bytes[i] << (8*(i - 4));
	writel(lo, &ehci_debug->data03);
	writel(hi, &ehci_debug->data47);
}

static inline void dbgp_get_data(void *buf, int size)
{
	unsigned char *bytes = buf;
	u32 lo, hi;
	int i;

	lo = readl(&ehci_debug->data03);
	hi = readl(&ehci_debug->data47);
	for (i = 0; i < 4 && i < size; i++)
		bytes[i] = (lo >> (8*i)) & 0xff;
	for (; i < 8 && i < size; i++)
		bytes[i] = (hi >> (8*(i - 4))) & 0xff;
}

static int dbgp_bulk_write(unsigned devnum, unsigned endpoint,
			 const char *bytes, int size)
{
	int ret;
	u32 addr;
	u32 pids, ctrl;

	if (size > DBGP_MAX_PACKET)
		return -1;

	addr = DBGP_EPADDR(devnum, endpoint);

	pids = readl(&ehci_debug->pids);
	pids = dbgp_pid_write_update(pids, USB_PID_OUT);

	ctrl = readl(&ehci_debug->control);
	ctrl = dbgp_len_update(ctrl, size);
	ctrl |= DBGP_OUT;
	ctrl |= DBGP_GO;

	dbgp_set_data(bytes, size);
	writel(addr, &ehci_debug->address);
	writel(pids, &ehci_debug->pids);
	ret = dbgp_wait_until_done(ctrl, DBGP_LOOPS);

	return ret;
}

static int dbgp_bulk_read(unsigned devnum, unsigned endpoint, void *data,
			  int size, int loops)
{
	u32 pids, addr, ctrl;
	int ret;

	if (size > DBGP_MAX_PACKET)
		return -1;

	addr = DBGP_EPADDR(devnum, endpoint);

	pids = readl(&ehci_debug->pids);
	pids = dbgp_pid_read_update(pids, USB_PID_IN);

	ctrl = readl(&ehci_debug->control);
	ctrl = dbgp_len_update(ctrl, size);
	ctrl &= ~DBGP_OUT;
	ctrl |= DBGP_GO;

	writel(addr, &ehci_debug->address);
	writel(pids, &ehci_debug->pids);
	ret = dbgp_wait_until_done(ctrl, loops);
	if (ret < 0)
		return ret;

	if (size > ret)
		size = ret;
	dbgp_get_data(data, size);
	return ret;
}

static int dbgp_control_msg(unsigned devnum, int requesttype,
	int request, int value, int index, void *data, int size)
{
	u32 pids, addr, ctrl;
	struct usb_ctrlrequest req;
	int read;
	int ret;

	read = (requesttype & USB_DIR_IN) != 0;
	if (size > (read ? DBGP_MAX_PACKET : 0))
		return -1;

	/* Compute the control message */
	req.bRequestType = requesttype;
	req.bRequest = request;
	req.wValue = cpu_to_le16(value);
	req.wIndex = cpu_to_le16(index);
	req.wLength = cpu_to_le16(size);

	pids = DBGP_PID_SET(USB_PID_DATA0, USB_PID_SETUP);
	addr = DBGP_EPADDR(devnum, 0);

	ctrl = readl(&ehci_debug->control);
	ctrl = dbgp_len_update(ctrl, sizeof(req));
	ctrl |= DBGP_OUT;
	ctrl |= DBGP_GO;

	/* Send the setup message */
	dbgp_set_data(&req, sizeof(req));
	writel(addr, &ehci_debug->address);
	writel(pids, &ehci_debug->pids);
	ret = dbgp_wait_until_done(ctrl, DBGP_LOOPS);
	if (ret < 0)
		return ret;

	/* Read the result */
	return dbgp_bulk_read(devnum, 0, data, size, DBGP_LOOPS);
}

/* Find a PCI capability */
static u32 __init find_cap(u32 num, u32 slot, u32 func, int cap)
{
	u8 pos;
	int bytes;

	if (!(read_pci_config_16(num, slot, func, PCI_STATUS) &
		PCI_STATUS_CAP_LIST))
		return 0;

	pos = read_pci_config_byte(num, slot, func, PCI_CAPABILITY_LIST);
	for (bytes = 0; bytes < 48 && pos >= 0x40; bytes++) {
		u8 id;

		pos &= ~3;
		id = read_pci_config_byte(num, slot, func, pos+PCI_CAP_LIST_ID);
		if (id == 0xff)
			break;
		if (id == cap)
			return pos;

		pos = read_pci_config_byte(num, slot, func,
						 pos+PCI_CAP_LIST_NEXT);
	}
	return 0;
}

static u32 __init __find_dbgp(u32 bus, u32 slot, u32 func)
{
	u32 class;

	class = read_pci_config(bus, slot, func, PCI_CLASS_REVISION);
	if ((class >> 8) != PCI_CLASS_SERIAL_USB_EHCI)
		return 0;

	return find_cap(bus, slot, func, PCI_CAP_ID_EHCI_DEBUG);
}

static u32 __init find_dbgp(int ehci_num, u32 *rbus, u32 *rslot, u32 *rfunc)
{
	u32 bus, slot, func;

	for (bus = 0; bus < 256; bus++) {
		for (slot = 0; slot < 32; slot++) {
			for (func = 0; func < 8; func++) {
				unsigned cap;

				cap = __find_dbgp(bus, slot, func);

				if (!cap)
					continue;
				if (ehci_num-- != 0)
					continue;
				*rbus = bus;
				*rslot = slot;
				*rfunc = func;
				return cap;
			}
		}
	}
	return 0;
}

static int dbgp_ehci_startup(void)
{
	u32 ctrl, cmd, status;
	int loop;

	/* Claim ownership, but do not enable yet */
	ctrl = readl(&ehci_debug->control);
	ctrl |= DBGP_OWNER;
	ctrl &= ~(DBGP_ENABLED | DBGP_INUSE);
	writel(ctrl, &ehci_debug->control);
	udelay(1);

	dbgp_ehci_status("EHCI startup");
	/* Start the ehci running */
	cmd = readl(&ehci_regs->command);
	cmd &= ~(CMD_LRESET | CMD_IAAD | CMD_PSE | CMD_ASE | CMD_RESET);
	cmd |= CMD_RUN;
	writel(cmd, &ehci_regs->command);

	/* Ensure everything is routed to the EHCI */
	writel(FLAG_CF, &ehci_regs->configured_flag);

	/* Wait until the controller is no longer halted */
	loop = 1000;
	do {
		status = readl(&ehci_regs->status);
		if (!(status & STS_HALT))
			break;
		udelay(1);
	} while (--loop > 0);

	if (!loop) {
		dbgp_printk("ehci can not be started\n");
		return -ENODEV;
	}
	dbgp_printk("ehci started\n");
	return 0;
}

static int dbgp_ehci_controller_reset(void)
{
	int loop = 250 * 1000;
	u32 cmd;

	/* Reset the EHCI controller */
	cmd = readl(&ehci_regs->command);
	cmd |= CMD_RESET;
	writel(cmd, &ehci_regs->command);
	do {
		cmd = readl(&ehci_regs->command);
	} while ((cmd & CMD_RESET) && (--loop > 0));

	if (!loop) {
		dbgp_printk("can not reset ehci\n");
		return -1;
	}
	dbgp_ehci_status("ehci reset done");
	return 0;
}
static int ehci_wait_for_port(int port);
/* Return 0 on success
 * Return -ENODEV for any general failure
 * Return -EIO if wait for port fails
 */
static int _dbgp_external_startup(void)
{
	int devnum;
	struct usb_debug_descriptor dbgp_desc;
	int ret;
	u32 ctrl, portsc, cmd;
	int dbg_port = dbgp_phys_port;
	int tries = 3;
	int reset_port_tries = 1;
	int try_hard_once = 1;

try_port_reset_again:
	ret = dbgp_ehci_startup();
	if (ret)
		return ret;

	/* Wait for a device to show up in the debug port */
	ret = ehci_wait_for_port(dbg_port);
	if (ret < 0) {
		portsc = readl(&ehci_regs->port_status[dbg_port - 1]);
		if (!(portsc & PORT_CONNECT) && try_hard_once) {
			/* Last ditch effort to try to force enable
			 * the debug device by using the packet test
			 * ehci command to try and wake it up. */
			try_hard_once = 0;
			cmd = readl(&ehci_regs->command);
			cmd &= ~CMD_RUN;
			writel(cmd, &ehci_regs->command);
			portsc = readl(&ehci_regs->port_status[dbg_port - 1]);
			portsc |= PORT_TEST_PKT;
			writel(portsc, &ehci_regs->port_status[dbg_port - 1]);
			dbgp_ehci_status("Trying to force debug port online");
			mdelay(50);
			dbgp_ehci_controller_reset();
			goto try_port_reset_again;
		} else if (reset_port_tries--) {
			goto try_port_reset_again;
		}
		dbgp_printk("No device found in debug port\n");
		return -EIO;
	}
	dbgp_ehci_status("wait for port done");

	/* Enable the debug port */
	ctrl = readl(&ehci_debug->control);
	ctrl |= DBGP_CLAIM;
	writel(ctrl, &ehci_debug->control);
	ctrl = readl(&ehci_debug->control);
	if ((ctrl & DBGP_CLAIM) != DBGP_CLAIM) {
		dbgp_printk("No device in debug port\n");
		writel(ctrl & ~DBGP_CLAIM, &ehci_debug->control);
		return -ENODEV;
	}
	dbgp_ehci_status("debug ported enabled");

	/* Completely transfer the debug device to the debug controller */
	portsc = readl(&ehci_regs->port_status[dbg_port - 1]);
	portsc &= ~PORT_PE;
	writel(portsc, &ehci_regs->port_status[dbg_port - 1]);

	dbgp_mdelay(100);

try_again:
	/* Find the debug device and make it device number 127 */
	for (devnum = 0; devnum <= 127; devnum++) {
		ret = dbgp_control_msg(devnum,
			USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
			USB_REQ_GET_DESCRIPTOR, (USB_DT_DEBUG << 8), 0,
			&dbgp_desc, sizeof(dbgp_desc));
		if (ret > 0)
			break;
	}
	if (devnum > 127) {
		dbgp_printk("Could not find attached debug device\n");
		goto err;
	}
	if (ret < 0) {
		dbgp_printk("Attached device is not a debug device\n");
		goto err;
	}
	dbgp_endpoint_out = dbgp_desc.bDebugOutEndpoint;
	dbgp_endpoint_in = dbgp_desc.bDebugInEndpoint;

	/* Move the device to 127 if it isn't already there */
	if (devnum != USB_DEBUG_DEVNUM) {
		ret = dbgp_control_msg(devnum,
			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
			USB_REQ_SET_ADDRESS, USB_DEBUG_DEVNUM, 0, NULL, 0);
		if (ret < 0) {
			dbgp_printk("Could not move attached device to %d\n",
				USB_DEBUG_DEVNUM);
			goto err;
		}
		devnum = USB_DEBUG_DEVNUM;
		dbgp_printk("debug device renamed to 127\n");
	}

	/* Enable the debug interface */
	ret = dbgp_control_msg(USB_DEBUG_DEVNUM,
		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
		USB_REQ_SET_FEATURE, USB_DEVICE_DEBUG_MODE, 0, NULL, 0);
	if (ret < 0) {
		dbgp_printk(" Could not enable the debug device\n");
		goto err;
	}
	dbgp_printk("debug interface enabled\n");
	/* Perform a small write to get the even/odd data state in sync
	 */
	ret = dbgp_bulk_write(USB_DEBUG_DEVNUM, dbgp_endpoint_out, " ", 1);
	if (ret < 0) {
		dbgp_printk("dbgp_bulk_write failed: %d\n", ret);
		goto err;
	}
	dbgp_printk("small write done\n");
	dbgp_not_safe = 0;

	return 0;
err:
	if (tries--)
		goto try_again;
	return -ENODEV;
}

static int ehci_reset_port(int port)
{
	u32 portsc;
	u32 delay_time, delay;
	int loop;

	dbgp_ehci_status("reset port");
	/* Reset the usb debug port */
	portsc = readl(&ehci_regs->port_status[port - 1]);
	portsc &= ~PORT_PE;
	portsc |= PORT_RESET;
	writel(portsc, &ehci_regs->port_status[port - 1]);

	delay = HUB_ROOT_RESET_TIME;
	for (delay_time = 0; delay_time < HUB_RESET_TIMEOUT;
	     delay_time += delay) {
		dbgp_mdelay(delay);
		portsc = readl(&ehci_regs->port_status[port - 1]);
		if (!(portsc & PORT_RESET))
			break;
	}
		if (portsc & PORT_RESET) {
			/* force reset to complete */
			loop = 100 * 1000;
			writel(portsc & ~(PORT_RWC_BITS | PORT_RESET),
				&ehci_regs->port_status[port - 1]);
			do {
				udelay(1);
				portsc = readl(&ehci_regs->port_status[port-1]);
			} while ((portsc & PORT_RESET) && (--loop > 0));
		}

		/* Device went away? */
		if (!(portsc & PORT_CONNECT))
			return -ENOTCONN;

		/* bomb out completely if something weird happened */
		if ((portsc & PORT_CSC))
			return -EINVAL;

		/* If we've finished resetting, then break out of the loop */
		if (!(portsc & PORT_RESET) && (portsc & PORT_PE))
			return 0;
	return -EBUSY;
}

static int ehci_wait_for_port(int port)
{
	u32 status;
	int ret, reps;

	for (reps = 0; reps < 300; reps++) {
		status = readl(&ehci_regs->status);
		if (status & STS_PCD)
			break;
		dbgp_mdelay(1);
	}
	ret = ehci_reset_port(port);
	if (ret == 0)
		return 0;
	return -ENOTCONN;
}

typedef void (*set_debug_port_t)(int port);

static void __init default_set_debug_port(int port)
{
}

static set_debug_port_t __initdata set_debug_port = default_set_debug_port;

static void __init nvidia_set_debug_port(int port)
{
	u32 dword;
	dword = read_pci_config(ehci_dev.bus, ehci_dev.slot, ehci_dev.func,
				 0x74);
	dword &= ~(0x0f<<12);
	dword |= ((port & 0x0f)<<12);
	write_pci_config(ehci_dev.bus, ehci_dev.slot, ehci_dev.func, 0x74,
				 dword);
	dbgp_printk("set debug port to %d\n", port);
}

static void __init detect_set_debug_port(void)
{
	u32 vendorid;

	vendorid = read_pci_config(ehci_dev.bus, ehci_dev.slot, ehci_dev.func,
		 0x00);

	if ((vendorid & 0xffff) == 0x10de) {
		dbgp_printk("using nvidia set_debug_port\n");
		set_debug_port = nvidia_set_debug_port;
	}
}

/* The code in early_ehci_bios_handoff() is derived from the usb pci
 * quirk initialization, but altered so as to use the early PCI
 * routines. */
#define EHCI_USBLEGSUP_BIOS	(1 << 16)	/* BIOS semaphore */
#define EHCI_USBLEGCTLSTS	4		/* legacy control/status */
static void __init early_ehci_bios_handoff(void)
{
	u32 hcc_params = readl(&ehci_caps->hcc_params);
	int offset = (hcc_params >> 8) & 0xff;
	u32 cap;
	int msec;

	if (!offset)
		return;

	cap = read_pci_config(ehci_dev.bus, ehci_dev.slot,
			      ehci_dev.func, offset);
	dbgp_printk("dbgp: ehci BIOS state %08x\n", cap);

	if ((cap & 0xff) == 1 && (cap & EHCI_USBLEGSUP_BIOS)) {
		dbgp_printk("dbgp: BIOS handoff\n");
		write_pci_config_byte(ehci_dev.bus, ehci_dev.slot,
				      ehci_dev.func, offset + 3, 1);
	}

	/* if boot firmware now owns EHCI, spin till it hands it over. */
	msec = 1000;
	while ((cap & EHCI_USBLEGSUP_BIOS) && (msec > 0)) {
		mdelay(10);
		msec -= 10;
		cap = read_pci_config(ehci_dev.bus, ehci_dev.slot,
				      ehci_dev.func, offset);
	}

	if (cap & EHCI_USBLEGSUP_BIOS) {
		/* well, possibly buggy BIOS... try to shut it down,
		 * and hope nothing goes too wrong */
		dbgp_printk("dbgp: BIOS handoff failed: %08x\n", cap);
		write_pci_config_byte(ehci_dev.bus, ehci_dev.slot,
				      ehci_dev.func, offset + 2, 0);
	}

	/* just in case, always disable EHCI SMIs */
	write_pci_config_byte(ehci_dev.bus, ehci_dev.slot, ehci_dev.func,
			      offset + EHCI_USBLEGCTLSTS, 0);
}

static int __init ehci_setup(void)
{
	u32 ctrl, portsc, hcs_params;
	u32 debug_port, new_debug_port = 0, n_ports;
	int ret, i;
	int port_map_tried;
	int playtimes = 3;

	early_ehci_bios_handoff();

try_next_time:
	port_map_tried = 0;

try_next_port:

	hcs_params = readl(&ehci_caps->hcs_params);
	debug_port = HCS_DEBUG_PORT(hcs_params);
	dbgp_phys_port = debug_port;
	n_ports    = HCS_N_PORTS(hcs_params);

	dbgp_printk("debug_port: %d\n", debug_port);
	dbgp_printk("n_ports:    %d\n", n_ports);
	dbgp_ehci_status("");

	for (i = 1; i <= n_ports; i++) {
		portsc = readl(&ehci_regs->port_status[i-1]);
		dbgp_printk("portstatus%d: %08x\n", i, portsc);
	}

	if (port_map_tried && (new_debug_port != debug_port)) {
		if (--playtimes) {
			set_debug_port(new_debug_port);
			goto try_next_time;
		}
		return -1;
	}

	/* Only reset the controller if it is not already in the
	 * configured state */
	if (!(readl(&ehci_regs->configured_flag) & FLAG_CF)) {
		if (dbgp_ehci_controller_reset() != 0)
			return -1;
	} else {
		dbgp_ehci_status("ehci skip - already configured");
	}

	ret = _dbgp_external_startup();
	if (ret == -EIO)
		goto next_debug_port;

	if (ret < 0) {
		/* Things didn't work so remove my claim */
		ctrl = readl(&ehci_debug->control);
		ctrl &= ~(DBGP_CLAIM | DBGP_OUT);
		writel(ctrl, &ehci_debug->control);
		return -1;
	}
	return 0;

next_debug_port:
	port_map_tried |= (1<<(debug_port - 1));
	new_debug_port = ((debug_port-1+1)%n_ports) + 1;
	if (port_map_tried != ((1<<n_ports) - 1)) {
		set_debug_port(new_debug_port);
		goto try_next_port;
	}
	if (--playtimes) {
		set_debug_port(new_debug_port);
		goto try_next_time;
	}

	return -1;
}

int __init early_dbgp_init(char *s)
{
	u32 debug_port, bar, offset;
	u32 bus, slot, func, cap;
	void __iomem *ehci_bar;
	u32 dbgp_num;
	u32 bar_val;
	char *e;
	int ret;
	u8 byte;

	if (!early_pci_allowed())
		return -1;

	dbgp_num = 0;
	if (*s)
		dbgp_num = simple_strtoul(s, &e, 10);
	dbgp_printk("dbgp_num: %d\n", dbgp_num);

	cap = find_dbgp(dbgp_num, &bus, &slot, &func);
	if (!cap)
		return -1;

	dbgp_printk("Found EHCI debug port on %02x:%02x.%1x\n", bus, slot,
			 func);

	debug_port = read_pci_config(bus, slot, func, cap);
	bar = (debug_port >> 29) & 0x7;
	bar = (bar * 4) + 0xc;
	offset = (debug_port >> 16) & 0xfff;
	dbgp_printk("bar: %02x offset: %03x\n", bar, offset);
	if (bar != PCI_BASE_ADDRESS_0) {
		dbgp_printk("only debug ports on bar 1 handled.\n");

		return -1;
	}

	bar_val = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
	dbgp_printk("bar_val: %02x offset: %03x\n", bar_val, offset);
	if (bar_val & ~PCI_BASE_ADDRESS_MEM_MASK) {
		dbgp_printk("only simple 32bit mmio bars supported\n");

		return -1;
	}

	/* double check if the mem space is enabled */
	byte = read_pci_config_byte(bus, slot, func, 0x04);
	if (!(byte & 0x2)) {
		byte  |= 0x02;
		write_pci_config_byte(bus, slot, func, 0x04, byte);
		dbgp_printk("mmio for ehci enabled\n");
	}

	/*
	 * FIXME I don't have the bar size so just guess PAGE_SIZE is more
	 * than enough.  1K is the biggest I have seen.
	 */
	set_fixmap_nocache(FIX_DBGP_BASE, bar_val & PAGE_MASK);
	ehci_bar = (void __iomem *)__fix_to_virt(FIX_DBGP_BASE);
	ehci_bar += bar_val & ~PAGE_MASK;
	dbgp_printk("ehci_bar: %p\n", ehci_bar);

	ehci_caps  = ehci_bar;
	ehci_regs  = ehci_bar + EARLY_HC_LENGTH(readl(&ehci_caps->hc_capbase));
	ehci_debug = ehci_bar + offset;
	ehci_dev.bus = bus;
	ehci_dev.slot = slot;
	ehci_dev.func = func;

	detect_set_debug_port();

	ret = ehci_setup();
	if (ret < 0) {
		dbgp_printk("ehci_setup failed\n");
		ehci_debug = NULL;

		return -1;
	}
	dbgp_ehci_status("early_init_complete");

	return 0;
}

static void early_dbgp_write(struct console *con, const char *str, u32 n)
{
	int chunk, ret;
	char buf[DBGP_MAX_PACKET];
	int use_cr = 0;
	u32 cmd, ctrl;
	int reset_run = 0;

	if (!ehci_debug || dbgp_not_safe)
		return;

	cmd = readl(&ehci_regs->command);
	if (unlikely(!(cmd & CMD_RUN))) {
		/* If the ehci controller is not in the run state do extended
		 * checks to see if the acpi or some other initialization also
		 * reset the ehci debug port */
		ctrl = readl(&ehci_debug->control);
		if (!(ctrl & DBGP_ENABLED)) {
			dbgp_not_safe = 1;
			_dbgp_external_startup();
		} else {
			cmd |= CMD_RUN;
			writel(cmd, &ehci_regs->command);
			reset_run = 1;
		}
	}
	while (n > 0) {
		for (chunk = 0; chunk < DBGP_MAX_PACKET && n > 0;
		     str++, chunk++, n--) {
			if (!use_cr && *str == '\n') {
				use_cr = 1;
				buf[chunk] = '\r';
				str--;
				n++;
				continue;
			}
			if (use_cr)
				use_cr = 0;
			buf[chunk] = *str;
		}
		if (chunk > 0) {
			ret = dbgp_bulk_write(USB_DEBUG_DEVNUM,
				      dbgp_endpoint_out, buf, chunk);
		}
	}
	if (unlikely(reset_run)) {
		cmd = readl(&ehci_regs->command);
		cmd &= ~CMD_RUN;
		writel(cmd, &ehci_regs->command);
	}
}

struct console early_dbgp_console = {
	.name =		"earlydbg",
	.write =	early_dbgp_write,
	.flags =	CON_PRINTBUFFER,
	.index =	-1,
};

#if IS_ENABLED(CONFIG_USB)
int dbgp_reset_prep(struct usb_hcd *hcd)
{
	int ret = xen_dbgp_reset_prep(hcd);
	u32 ctrl;

	if (ret)
		return ret;

	dbgp_not_safe = 1;
	if (!ehci_debug)
		return 0;

	if ((early_dbgp_console.index != -1 &&
	     !(early_dbgp_console.flags & CON_BOOT)) ||
	    dbgp_kgdb_mode)
		return 1;
	/* This means the console is not initialized, or should get
	 * shutdown so as to allow for reuse of the usb device, which
	 * means it is time to shutdown the usb debug port. */
	ctrl = readl(&ehci_debug->control);
	if (ctrl & DBGP_ENABLED) {
		ctrl &= ~(DBGP_CLAIM);
		writel(ctrl, &ehci_debug->control);
	}
	return 0;
}
EXPORT_SYMBOL_GPL(dbgp_reset_prep);

int dbgp_external_startup(struct usb_hcd *hcd)
{
	return xen_dbgp_external_startup(hcd) ?: _dbgp_external_startup();
}
EXPORT_SYMBOL_GPL(dbgp_external_startup);
#endif /* USB */

#ifdef CONFIG_KGDB

static char kgdbdbgp_buf[DBGP_MAX_PACKET];
static int kgdbdbgp_buf_sz;
static int kgdbdbgp_buf_idx;
static int kgdbdbgp_loop_cnt = DBGP_LOOPS;

static int kgdbdbgp_read_char(void)
{
	int ret;

	if (kgdbdbgp_buf_idx < kgdbdbgp_buf_sz) {
		char ch = kgdbdbgp_buf[kgdbdbgp_buf_idx++];
		return ch;
	}

	ret = dbgp_bulk_read(USB_DEBUG_DEVNUM, dbgp_endpoint_in,
			     &kgdbdbgp_buf, DBGP_MAX_PACKET,
			     kgdbdbgp_loop_cnt);
	if (ret <= 0)
		return NO_POLL_CHAR;
	kgdbdbgp_buf_sz = ret;
	kgdbdbgp_buf_idx = 1;
	return kgdbdbgp_buf[0];
}

static void kgdbdbgp_write_char(u8 chr)
{
	early_dbgp_write(NULL, &chr, 1);
}

static struct kgdb_io kgdbdbgp_io_ops = {
	.name = "kgdbdbgp",
	.read_char = kgdbdbgp_read_char,
	.write_char = kgdbdbgp_write_char,
};

static int kgdbdbgp_wait_time;

static int __init kgdbdbgp_parse_config(char *str)
{
	char *ptr;

	if (!ehci_debug) {
		if (early_dbgp_init(str))
			return -1;
	}
	ptr = strchr(str, ',');
	if (ptr) {
		ptr++;
		kgdbdbgp_wait_time = simple_strtoul(ptr, &ptr, 10);
	}
	kgdb_register_io_module(&kgdbdbgp_io_ops);
	kgdbdbgp_io_ops.is_console = early_dbgp_console.index != -1;

	return 0;
}
early_param("kgdbdbgp", kgdbdbgp_parse_config);

static int kgdbdbgp_reader_thread(void *ptr)
{
	int ret;

	while (readl(&ehci_debug->control) & DBGP_ENABLED) {
		kgdbdbgp_loop_cnt = 1;
		ret = kgdbdbgp_read_char();
		kgdbdbgp_loop_cnt = DBGP_LOOPS;
		if (ret != NO_POLL_CHAR) {
			if (ret == 0x3 || ret == '$') {
				if (ret == '$')
					kgdbdbgp_buf_idx--;
				kgdb_breakpoint();
			}
			continue;
		}
		schedule_timeout_interruptible(kgdbdbgp_wait_time * HZ);
	}
	return 0;
}

static int __init kgdbdbgp_start_thread(void)
{
	if (dbgp_kgdb_mode && kgdbdbgp_wait_time)
		kthread_run(kgdbdbgp_reader_thread, NULL, "%s", "dbgp");

	return 0;
}
module_init(kgdbdbgp_start_thread);
#endif /* CONFIG_KGDB */