summaryrefslogtreecommitdiffstats
path: root/Documentation/usb/gadget-testing.rst
blob: 29072c166d236a25e175df3f1677b607a4449013 (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
==============
Gadget Testing
==============

This file summarizes information on basic testing of USB functions
provided by gadgets.

.. contents

   1. ACM function
   2. ECM function
   3. ECM subset function
   4. EEM function
   5. FFS function
   6. HID function
   7. LOOPBACK function
   8. MASS STORAGE function
   9. MIDI function
   10. NCM function
   11. OBEX function
   12. PHONET function
   13. RNDIS function
   14. SERIAL function
   15. SOURCESINK function
   16. UAC1 function (legacy implementation)
   17. UAC2 function
   18. UVC function
   19. PRINTER function
   20. UAC1 function (new API)
   21. MIDI2 function


1. ACM function
===============

The function is provided by usb_f_acm.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "acm".
The ACM function provides just one attribute in its function directory:

	port_num

The attribute is read-only.

There can be at most 4 ACM/generic serial/OBEX ports in the system.


Testing the ACM function
------------------------

On the host::

	cat > /dev/ttyACM<X>

On the device::

	cat /dev/ttyGS<Y>

then the other way round

On the device::

	cat > /dev/ttyGS<Y>

On the host::

	cat /dev/ttyACM<X>

2. ECM function
===============

The function is provided by usb_f_ecm.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "ecm".
The ECM function provides these attributes in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	qmult		queue length multiplier for high and super speed
	host_addr	MAC address of host's end of this
			Ethernet over USB link
	dev_addr	MAC address of device's end of this
			Ethernet over USB link
	=============== ==================================================

and after creating the functions/ecm.<instance name> they contain default
values: qmult is 5, dev_addr and host_addr are randomly selected.
The ifname can be written to if the function is not bound. A write must be an
interface pattern such as "usb%d", which will cause the net core to choose the
next free usbX interface. By default, it is set to "usb%d".

Testing the ECM function
------------------------

Configure IP addresses of the device and the host. Then:

On the device::

	ping <host's IP>

On the host::

	ping <device's IP>

3. ECM subset function
======================

The function is provided by usb_f_ecm_subset.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "geth".
The ECM subset function provides these attributes in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	qmult		queue length multiplier for high and super speed
	host_addr	MAC address of host's end of this
			Ethernet over USB link
	dev_addr	MAC address of device's end of this
			Ethernet over USB link
	=============== ==================================================

and after creating the functions/ecm.<instance name> they contain default
values: qmult is 5, dev_addr and host_addr are randomly selected.
The ifname can be written to if the function is not bound. A write must be an
interface pattern such as "usb%d", which will cause the net core to choose the
next free usbX interface. By default, it is set to "usb%d".

Testing the ECM subset function
-------------------------------

Configure IP addresses of the device and the host. Then:

On the device::

	ping <host's IP>

On the host::

	ping <device's IP>

4. EEM function
===============

The function is provided by usb_f_eem.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "eem".
The EEM function provides these attributes in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	qmult		queue length multiplier for high and super speed
	host_addr	MAC address of host's end of this
			Ethernet over USB link
	dev_addr	MAC address of device's end of this
			Ethernet over USB link
	=============== ==================================================

and after creating the functions/eem.<instance name> they contain default
values: qmult is 5, dev_addr and host_addr are randomly selected.
The ifname can be written to if the function is not bound. A write must be an
interface pattern such as "usb%d", which will cause the net core to choose the
next free usbX interface. By default, it is set to "usb%d".

Testing the EEM function
------------------------

Configure IP addresses of the device and the host. Then:

On the device::

	ping <host's IP>

On the host::

	ping <device's IP>

5. FFS function
===============

The function is provided by usb_f_fs.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "ffs".
The function directory is intentionally empty and not modifiable.

After creating the directory there is a new instance (a "device") of FunctionFS
available in the system. Once a "device" is available, the user should follow
the standard procedure for using FunctionFS (mount it, run the userspace
process which implements the function proper). The gadget should be enabled
by writing a suitable string to usb_gadget/<gadget>/UDC.

Testing the FFS function
------------------------

On the device: start the function's userspace daemon, enable the gadget

On the host: use the USB function provided by the device

6. HID function
===============

The function is provided by usb_f_hid.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "hid".
The HID function provides these attributes in its function directory:

	=============== ===========================================
	protocol	HID protocol to use
	report_desc	data to be used in HID reports, except data
			passed with /dev/hidg<X>
	report_length	HID report length
	subclass	HID subclass to use
	=============== ===========================================

For a keyboard the protocol and the subclass are 1, the report_length is 8,
while the report_desc is::

  $ hd my_report_desc
  00000000  05 01 09 06 a1 01 05 07  19 e0 29 e7 15 00 25 01  |..........)...%.|
  00000010  75 01 95 08 81 02 95 01  75 08 81 03 95 05 75 01  |u.......u.....u.|
  00000020  05 08 19 01 29 05 91 02  95 01 75 03 91 03 95 06  |....).....u.....|
  00000030  75 08 15 00 25 65 05 07  19 00 29 65 81 00 c0     |u...%e....)e...|
  0000003f

Such a sequence of bytes can be stored to the attribute with echo::

  $ echo -ne \\x05\\x01\\x09\\x06\\xa1.....

Testing the HID function
------------------------

Device:

- create the gadget
- connect the gadget to a host, preferably not the one used
  to control the gadget
- run a program which writes to /dev/hidg<N>, e.g.
  a userspace program found in Documentation/usb/gadget_hid.rst::

	$ ./hid_gadget_test /dev/hidg0 keyboard

Host:

- observe the keystrokes from the gadget

7. LOOPBACK function
====================

The function is provided by usb_f_ss_lb.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "Loopback".
The LOOPBACK function provides these attributes in its function directory:

	=============== =======================
	qlen		depth of loopback queue
	bulk_buflen	buffer length
	=============== =======================

Testing the LOOPBACK function
-----------------------------

device: run the gadget

host: test-usb (tools/usb/testusb.c)

8. MASS STORAGE function
========================

The function is provided by usb_f_mass_storage.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "mass_storage".
The MASS STORAGE function provides these attributes in its directory:
files:

	=============== ==============================================
	stall		Set to permit function to halt bulk endpoints.
			Disabled on some USB devices known not to work
			correctly. You should set it to true.
	num_buffers	Number of pipeline buffers. Valid numbers
			are 2..4. Available only if
			CONFIG_USB_GADGET_DEBUG_FILES is set.
	=============== ==============================================

and a default lun.0 directory corresponding to SCSI LUN #0.

A new lun can be added with mkdir::

	$ mkdir functions/mass_storage.0/partition.5

Lun numbering does not have to be continuous, except for lun #0 which is
created by default. A maximum of 8 luns can be specified and they all must be
named following the <name>.<number> scheme. The numbers can be 0..8.
Probably a good convention is to name the luns "lun.<number>",
although it is not mandatory.

In each lun directory there are the following attribute files:

	=============== ==============================================
	file		The path to the backing file for the LUN.
			Required if LUN is not marked as removable.
	ro		Flag specifying access to the LUN shall be
			read-only. This is implied if CD-ROM emulation
			is enabled as well as when it was impossible
			to open "filename" in R/W mode.
	removable	Flag specifying that LUN shall be indicated as
			being removable.
	cdrom		Flag specifying that LUN shall be reported as
			being a CD-ROM.
	nofua		Flag specifying that FUA flag
			in SCSI WRITE(10,12)
	forced_eject	This write-only file is useful only when
			the function is active. It causes the backing
			file to be forcibly detached from the LUN,
			regardless of whether the host has allowed it.
			Any non-zero number of bytes written will
			result in ejection.
	=============== ==============================================

Testing the MASS STORAGE function
---------------------------------

device: connect the gadget, enable it
host: dmesg, see the USB drives appear (if system configured to automatically
mount)

9. MIDI function
================

The function is provided by usb_f_midi.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "midi".
The MIDI function provides these attributes in its function directory:

	=============== ====================================
	buflen		MIDI buffer length
	id		ID string for the USB MIDI adapter
	in_ports	number of MIDI input ports
	index		index value for the USB MIDI adapter
	out_ports	number of MIDI output ports
	qlen		USB read request queue length
	=============== ====================================

Testing the MIDI function
-------------------------

There are two cases: playing a mid from the gadget to
the host and playing a mid from the host to the gadget.

1) Playing a mid from the gadget to the host:

host::

  $ arecordmidi -l
   Port    Client name                      Port name
   14:0    Midi Through                     Midi Through Port-0
   24:0    MIDI Gadget                      MIDI Gadget MIDI 1
  $ arecordmidi -p 24:0 from_gadget.mid

gadget::

  $ aplaymidi -l
   Port    Client name                      Port name
   20:0    f_midi                           f_midi

  $ aplaymidi -p 20:0 to_host.mid

2) Playing a mid from the host to the gadget

gadget::

  $ arecordmidi -l
   Port    Client name                      Port name
   20:0    f_midi                           f_midi

  $ arecordmidi -p 20:0 from_host.mid

host::

  $ aplaymidi -l
   Port    Client name                      Port name
   14:0    Midi Through                     Midi Through Port-0
   24:0    MIDI Gadget                      MIDI Gadget MIDI 1

  $ aplaymidi -p24:0 to_gadget.mid

The from_gadget.mid should sound identical to the to_host.mid.

The from_host.id should sound identical to the to_gadget.mid.

MIDI files can be played to speakers/headphones with e.g. timidity installed::

  $ aplaymidi -l
   Port    Client name                      Port name
   14:0    Midi Through                     Midi Through Port-0
   24:0    MIDI Gadget                      MIDI Gadget MIDI 1
  128:0    TiMidity                         TiMidity port 0
  128:1    TiMidity                         TiMidity port 1
  128:2    TiMidity                         TiMidity port 2
  128:3    TiMidity                         TiMidity port 3

  $ aplaymidi -p 128:0 file.mid

MIDI ports can be logically connected using the aconnect utility, e.g.::

  $ aconnect 24:0 128:0 # try it on the host

After the gadget's MIDI port is connected to timidity's MIDI port,
whatever is played at the gadget side with aplaymidi -l is audible
in host's speakers/headphones.

10. NCM function
================

The function is provided by usb_f_ncm.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "ncm".
The NCM function provides these attributes in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	qmult		queue length multiplier for high and super speed
	host_addr	MAC address of host's end of this
			Ethernet over USB link
	dev_addr	MAC address of device's end of this
			Ethernet over USB link
	=============== ==================================================

and after creating the functions/ncm.<instance name> they contain default
values: qmult is 5, dev_addr and host_addr are randomly selected.
The ifname can be written to if the function is not bound. A write must be an
interface pattern such as "usb%d", which will cause the net core to choose the
next free usbX interface. By default, it is set to "usb%d".

Testing the NCM function
------------------------

Configure IP addresses of the device and the host. Then:

On the device::

	ping <host's IP>

On the host::

	ping <device's IP>

11. OBEX function
=================

The function is provided by usb_f_obex.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "obex".
The OBEX function provides just one attribute in its function directory:

	port_num

The attribute is read-only.

There can be at most 4 ACM/generic serial/OBEX ports in the system.

Testing the OBEX function
-------------------------

On device::

	seriald -f /dev/ttyGS<Y> -s 1024

On host::

	serialc -v <vendorID> -p <productID> -i<interface#> -a1 -s1024 \
                -t<out endpoint addr> -r<in endpoint addr>

where seriald and serialc are Felipe's utilities found here:

	https://github.com/felipebalbi/usb-tools.git master

12. PHONET function
===================

The function is provided by usb_f_phonet.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "phonet".
The PHONET function provides just one attribute in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	=============== ==================================================

Testing the PHONET function
---------------------------

It is not possible to test the SOCK_STREAM protocol without a specific piece
of hardware, so only SOCK_DGRAM has been tested. For the latter to work,
in the past I had to apply the patch mentioned here:

http://www.spinics.net/lists/linux-usb/msg85689.html

These tools are required:

git://git.gitorious.org/meego-cellular/phonet-utils.git

On the host::

	$ ./phonet -a 0x10 -i usbpn0
	$ ./pnroute add 0x6c usbpn0
	$./pnroute add 0x10 usbpn0
	$ ifconfig usbpn0 up

On the device::

	$ ./phonet -a 0x6c -i upnlink0
	$ ./pnroute add 0x10 upnlink0
	$ ifconfig upnlink0 up

Then a test program can be used::

	http://www.spinics.net/lists/linux-usb/msg85690.html

On the device::

	$ ./pnxmit -a 0x6c -r

On the host::

	$ ./pnxmit -a 0x10 -s 0x6c

As a result some data should be sent from host to device.
Then the other way round:

On the host::

	$ ./pnxmit -a 0x10 -r

On the device::

	$ ./pnxmit -a 0x6c -s 0x10

13. RNDIS function
==================

The function is provided by usb_f_rndis.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "rndis".
The RNDIS function provides these attributes in its function directory:

	=============== ==================================================
	ifname		network device interface name associated with this
			function instance
	qmult		queue length multiplier for high and super speed
	host_addr	MAC address of host's end of this
			Ethernet over USB link
	dev_addr	MAC address of device's end of this
			Ethernet over USB link
	=============== ==================================================

and after creating the functions/rndis.<instance name> they contain default
values: qmult is 5, dev_addr and host_addr are randomly selected.
The ifname can be written to if the function is not bound. A write must be an
interface pattern such as "usb%d", which will cause the net core to choose the
next free usbX interface. By default, it is set to "usb%d".

Testing the RNDIS function
--------------------------

Configure IP addresses of the device and the host. Then:

On the device::

	ping <host's IP>

On the host::

	ping <device's IP>

14. SERIAL function
===================

The function is provided by usb_f_gser.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "gser".
The SERIAL function provides just one attribute in its function directory:

	port_num

The attribute is read-only.

There can be at most 4 ACM/generic serial/OBEX ports in the system.

Testing the SERIAL function
---------------------------

On host::

	insmod usbserial
	echo VID PID >/sys/bus/usb-serial/drivers/generic/new_id

On host::

	cat > /dev/ttyUSB<X>

On target::

	cat /dev/ttyGS<Y>

then the other way round

On target::

	cat > /dev/ttyGS<Y>

On host::

	cat /dev/ttyUSB<X>

15. SOURCESINK function
=======================

The function is provided by usb_f_ss_lb.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "SourceSink".
The SOURCESINK function provides these attributes in its function directory:

	=============== ==================================
	pattern		0 (all zeros), 1 (mod63), 2 (none)
	isoc_interval	1..16
	isoc_maxpacket	0 - 1023 (fs), 0 - 1024 (hs/ss)
	isoc_mult	0..2 (hs/ss only)
	isoc_maxburst	0..15 (ss only)
	bulk_buflen	buffer length
	bulk_qlen	depth of queue for bulk
	iso_qlen	depth of queue for iso
	=============== ==================================

Testing the SOURCESINK function
-------------------------------

device: run the gadget

host: test-usb (tools/usb/testusb.c)


16. UAC1 function (legacy implementation)
=========================================

The function is provided by usb_f_uac1_legacy.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory
is "uac1_legacy".
The uac1 function provides these attributes in its function directory:

	=============== ====================================
	audio_buf_size	audio buffer size
	fn_cap		capture pcm device file name
	fn_cntl		control device file name
	fn_play		playback pcm device file name
	req_buf_size	ISO OUT endpoint request buffer size
	req_count	ISO OUT endpoint request count
	=============== ====================================

The attributes have sane default values.

Testing the UAC1 function
-------------------------

device: run the gadget

host::

	aplay -l # should list our USB Audio Gadget

17. UAC2 function
=================

The function is provided by usb_f_uac2.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "uac2".
The uac2 function provides these attributes in its function directory:

	================ ====================================================
	c_chmask         capture channel mask
	c_srate          list of capture sampling rates (comma-separated)
	c_ssize          capture sample size (bytes)
	c_sync           capture synchronization type (async/adaptive)
	c_mute_present   capture mute control enable
	c_volume_present capture volume control enable
	c_volume_min     capture volume control min value (in 1/256 dB)
	c_volume_max     capture volume control max value (in 1/256 dB)
	c_volume_res     capture volume control resolution (in 1/256 dB)
	c_hs_bint        capture bInterval for HS/SS (1-4: fixed, 0: auto)
	fb_max           maximum extra bandwidth in async mode
	p_chmask         playback channel mask
	p_srate          list of playback sampling rates (comma-separated)
	p_ssize          playback sample size (bytes)
	p_mute_present   playback mute control enable
	p_volume_present playback volume control enable
	p_volume_min     playback volume control min value (in 1/256 dB)
	p_volume_max     playback volume control max value (in 1/256 dB)
	p_volume_res     playback volume control resolution (in 1/256 dB)
	p_hs_bint        playback bInterval for HS/SS (1-4: fixed, 0: auto)
	req_number       the number of pre-allocated request for both capture
	                 and playback
	function_name    name of the interface
	c_terminal_type  code of the capture terminal type
	p_terminal_type  code of the playback terminal type
	================ ====================================================

The attributes have sane default values.

Testing the UAC2 function
-------------------------

device: run the gadget
host: aplay -l # should list our USB Audio Gadget

This function does not require real hardware support, it just
sends a stream of audio data to/from the host. In order to
actually hear something at the device side, a command similar
to this must be used at the device side::

	$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &

e.g.::

	$ arecord -f dat -t wav -D hw:CARD=UAC2Gadget,DEV=0 | \
	  aplay -D default:CARD=OdroidU3

18. UVC function
================

The function is provided by usb_f_uvc.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "uvc".
The uvc function provides these attributes in its function directory:

	=================== ================================================
	streaming_interval  interval for polling endpoint for data transfers
	streaming_maxburst  bMaxBurst for super speed companion descriptor
	streaming_maxpacket maximum packet size this endpoint is capable of
			    sending or receiving when this configuration is
			    selected
	function_name       name of the interface
	=================== ================================================

There are also "control" and "streaming" subdirectories, each of which contain
a number of their subdirectories. There are some sane defaults provided, but
the user must provide the following:

	================== ====================================================
	control header     create in control/header, link from control/class/fs
			   and/or control/class/ss
	streaming header   create in streaming/header, link from
			   streaming/class/fs and/or streaming/class/hs and/or
			   streaming/class/ss
	format description create in streaming/mjpeg and/or
			   streaming/uncompressed
	frame description  create in streaming/mjpeg/<format> and/or in
			   streaming/uncompressed/<format>
	================== ====================================================

Each frame description contains frame interval specification, and each
such specification consists of a number of lines with an interval value
in each line. The rules stated above are best illustrated with an example::

  # mkdir functions/uvc.usb0/control/header/h
  # cd functions/uvc.usb0/control/
  # ln -s header/h class/fs
  # ln -s header/h class/ss
  # mkdir -p functions/uvc.usb0/streaming/uncompressed/u/360p
  # cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwFrameInterval
  666666
  1000000
  5000000
  EOF
  # cd $GADGET_CONFIGFS_ROOT
  # mkdir functions/uvc.usb0/streaming/header/h
  # cd functions/uvc.usb0/streaming/header/h
  # ln -s ../../uncompressed/u
  # cd ../../class/fs
  # ln -s ../../header/h
  # cd ../../class/hs
  # ln -s ../../header/h
  # cd ../../class/ss
  # ln -s ../../header/h


Testing the UVC function
------------------------

device: run the gadget, modprobe vivid::

  # uvc-gadget -u /dev/video<uvc video node #> -v /dev/video<vivid video node #>

where uvc-gadget is this program:
	http://git.ideasonboard.org/uvc-gadget.git

with these patches:

	http://www.spinics.net/lists/linux-usb/msg99220.html

host::

	luvcview -f yuv

19. PRINTER function
====================

The function is provided by usb_f_printer.ko module.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "printer".
The printer function provides these attributes in its function directory:

	==========	===========================================
	pnp_string	Data to be passed to the host in pnp string
	q_len		Number of requests per endpoint
	==========	===========================================

Testing the PRINTER function
----------------------------

The most basic testing:

device: run the gadget::

	# ls -l /devices/virtual/usb_printer_gadget/

should show g_printer<number>.

If udev is active, then /dev/g_printer<number> should appear automatically.

host:

If udev is active, then e.g. /dev/usb/lp0 should appear.

host->device transmission:

device::

	# cat /dev/g_printer<number>

host::

	# cat > /dev/usb/lp0

device->host transmission::

	# cat > /dev/g_printer<number>

host::

	# cat /dev/usb/lp0

More advanced testing can be done with the prn_example
described in Documentation/usb/gadget_printer.rst.


20. UAC1 function (virtual ALSA card, using u_audio API)
========================================================

The function is provided by usb_f_uac1.ko module.
It will create a virtual ALSA card and the audio streams are simply
sinked to and sourced from it.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "uac1".
The uac1 function provides these attributes in its function directory:

	================ ====================================================
	c_chmask         capture channel mask
	c_srate          list of capture sampling rates (comma-separated)
	c_ssize          capture sample size (bytes)
	c_mute_present   capture mute control enable
	c_volume_present capture volume control enable
	c_volume_min     capture volume control min value (in 1/256 dB)
	c_volume_max     capture volume control max value (in 1/256 dB)
	c_volume_res     capture volume control resolution (in 1/256 dB)
	p_chmask         playback channel mask
	p_srate          list of playback sampling rates (comma-separated)
	p_ssize          playback sample size (bytes)
	p_mute_present   playback mute control enable
	p_volume_present playback volume control enable
	p_volume_min     playback volume control min value (in 1/256 dB)
	p_volume_max     playback volume control max value (in 1/256 dB)
	p_volume_res     playback volume control resolution (in 1/256 dB)
	req_number       the number of pre-allocated requests for both capture
	                 and playback
	function_name    name of the interface
	================ ====================================================

The attributes have sane default values.

Testing the UAC1 function
-------------------------

device: run the gadget
host: aplay -l # should list our USB Audio Gadget

This function does not require real hardware support, it just
sends a stream of audio data to/from the host. In order to
actually hear something at the device side, a command similar
to this must be used at the device side::

	$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &

e.g.::

	$ arecord -f dat -t wav -D hw:CARD=UAC1Gadget,DEV=0 | \
	  aplay -D default:CARD=OdroidU3


21. MIDI2 function
==================

The function is provided by usb_f_midi2.ko module.
It will create a virtual ALSA card containing a UMP rawmidi device
where the UMP packet is looped back. In addition, a legacy rawmidi
device is created. The UMP rawmidi is bound with ALSA sequencer
clients, too.

Function-specific configfs interface
------------------------------------

The function name to use when creating the function directory is "midi2".
The midi2 function provides these attributes in its function directory
as the card top-level information:

	=============	=================================================
	process_ump	Bool flag to process UMP Stream messages (0 or 1)
	static_block	Bool flag for static blocks (0 or 1)
	iface_name	Optional interface name string
	=============	=================================================

The directory contains a subdirectory "ep.0", and this provides the
attributes for a UMP Endpoint (which is a pair of USB MIDI Endpoints):

	=============	=================================================
	protocol_caps	MIDI protocol capabilities;
			1: MIDI 1.0, 2: MIDI 2.0, or 3: both protocols
	protocol	Default MIDI protocol (either 1 or 2)
	ep_name		UMP Endpoint name string
	product_id	Product ID string
	manufacturer	Manufacture ID number (24 bit)
	family		Device family ID number (16 bit)
	model		Device model ID number (16 bit)
	sw_revision	Software revision (32 bit)
	=============	=================================================

Each Endpoint subdirectory contains a subdirectory "block.0", which
represents the Function Block for Block 0 information.
Its attributes are:

	=================	===============================================
	name			Function Block name string
	direction		Direction of this FB
				1: input, 2: output, or 3: bidirectional
	first_group		The first UMP Group number (0-15)
	num_groups		The number of groups in this FB (1-16)
	midi1_first_group	The first UMP Group number for MIDI 1.0 (0-15)
	midi1_num_groups	The number of groups for MIDI 1.0 (0-16)
	ui_hint			UI-hint of this FB
				0: unknown, 1: receiver, 2: sender, 3: both
	midi_ci_verison		Supported MIDI-CI version number (8 bit)
	is_midi1		Legacy MIDI 1.0 device (0-2)
				0: MIDI 2.0 device,
				1: MIDI 1.0 without restriction, or
				2: MIDI 1.0 with low speed
	sysex8_streams		Max number of SysEx8 streams (8 bit)
	active			Bool flag for FB activity (0 or 1)
	=================	===============================================

If multiple Function Blocks are required, you can add more Function
Blocks by creating subdirectories "block.<num>" with the corresponding
Function Block number (1, 2, ....). The FB subdirectories can be
dynamically removed, too. Note that the Function Block numbers must be
continuous.

Similarly, if you multiple UMP Endpoints are required, you can add
more Endpoints by creating subdirectories "ep.<num>". The number must
be continuous.

For emulating the old MIDI 2.0 device without UMP v1.1 support, pass 0
to `process_ump` flag. Then the whole UMP v1.1 requests are ignored.

Testing the MIDI2 function
--------------------------

On the device: run the gadget, and running::

  $ cat /proc/asound/cards

will show a new sound card containing a MIDI2 device.

OTOH, on the host::

  $ cat /proc/asound/cards

will show a new sound card containing either MIDI1 or MIDI2 device,
depending on the USB audio driver configuration.

On both, when ALSA sequencer is enabled on the host, you can find the
UMP MIDI client such as "MIDI 2.0 Gadget".

As the driver simply loops back the data, there is no need for a real
device just for testing.

For testing a MIDI input from the gadget to the host (e.g. emulating a
MIDI keyboard), you can send a MIDI stream like the following.

On the gadget::

  $ aconnect -o
  ....
  client 20: 'MIDI 2.0 Gadget' [type=kernel,card=1]
      0 'MIDI 2.0        '
      1 'Group 1 (MIDI 2.0 Gadget I/O)'
  $ aplaymidi -p 20:1 to_host.mid

On the host::

  $ aconnect -i
  ....
  client 24: 'MIDI 2.0 Gadget' [type=kernel,card=2]
      0 'MIDI 2.0        '
      1 'Group 1 (MIDI 2.0 Gadget I/O)'
  $ arecordmidi -p 24:1 from_gadget.mid

If you have a UMP-capable application, you can use the UMP port to
send/receive the raw UMP packets, too. For example, aseqdump program
with UMP support can receive from UMP port. On the host::

  $ aseqdump -u 2 -p 24:1
  Waiting for data. Press Ctrl+C to end.
  Source  Group    Event                  Ch  Data
   24:1   Group  0, Program change          0, program 0, Bank select 0:0
   24:1   Group  0, Channel pressure        0, value 0x80000000

For testing a MIDI output to the gadget to the host (e.g. emulating a
MIDI synth), it'll be just other way round.

On the gadget::

  $ arecordmidi -p 20:1 from_host.mid

On the host::

  $ aplaymidi -p 24:1 to_gadget.mid

The access to MIDI 1.0 on altset 0 on the host is supported, and it's
translated from/to UMP packets on the gadget. It's bound to only
Function Block 0.

The current operation mode can be observed in ALSA control element
"Operation Mode" for SND_CTL_IFACE_RAWMIDI.  For example::

  $ amixer -c1 contents
  numid=1,iface=RAWMIDI,name='Operation Mode'
    ; type=INTEGER,access=r--v----,values=1,min=0,max=2,step=0
    : values=2

where 0 = unused, 1 = MIDI 1.0 (altset 0), 2 = MIDI 2.0 (altset 1).
The example above shows it's running in 2, i.e. MIDI 2.0.