This file summarizes information on basic testing of USB functions provided by gadgets.
The function is provided by usb_f_acm.ko module.
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.
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>
The function is provided by usb_f_ecm.ko module.
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. Except for ifname they can be written to until the function is linked to a configuration. The ifname is read-only and contains the name of the interface which was assigned by the net core, e. g. usb0.
Configure IP addresses of the device and the host. Then:
On the device:
ping <host's IP>
On the host:
ping <device's IP>
The function is provided by usb_f_ecm_subset.ko module.
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. Except for ifname they can be written to until the function is linked to a configuration. The ifname is read-only and contains the name of the interface which was assigned by the net core, e. g. usb0.
Configure IP addresses of the device and the host. Then:
On the device:
ping <host's IP>
On the host:
ping <device's IP>
The function is provided by usb_f_eem.ko module.
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. Except for ifname they can be written to until the function is linked to a configuration. The ifname is read-only and contains the name of the interface which was assigned by the net core, e. g. usb0.
Configure IP addresses of the device and the host. Then:
On the device:
ping <host's IP>
On the host:
ping <device's IP>
The function is provided by usb_f_fs.ko module.
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.
On the device: start the function's userspace daemon, enable the gadget
On the host: use the USB function provided by the device
The function is provided by usb_f_hid.ko module.
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.....
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
The function is provided by usb_f_ss_lb.ko module.
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
device: run the gadget
host: test-usb (tools/usb/testusb.c)
The function is provided by usb_f_mass_storage.ko module.
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)
device: connect the gadget, enable it host: dmesg, see the USB drives appear (if system configured to automatically mount)
The function is provided by usb_f_midi.ko module.
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
There are two cases: playing a mid from the gadget to the host and playing a mid from the host to the gadget.
- 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
- 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.
The function is provided by usb_f_ncm.ko module.
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. Except for ifname they can be written to until the function is linked to a configuration. The ifname is read-only and contains the name of the interface which was assigned by the net core, e. g. usb0.
Configure IP addresses of the device and the host. Then:
On the device:
ping <host's IP>
On the host:
ping <device's IP>
The function is provided by usb_f_obex.ko module.
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.
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
The function is provided by usb_f_phonet.ko module.
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
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
The function is provided by usb_f_rndis.ko module.
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. Except for ifname they can be written to until the function is linked to a configuration. The ifname is read-only and contains the name of the interface which was assigned by the net core, e. g. usb0.
Configure IP addresses of the device and the host. Then:
On the device:
ping <host's IP>
On the host:
ping <device's IP>
The function is provided by usb_f_gser.ko module.
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.
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>
The function is provided by usb_f_ss_lb.ko module.
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
device: run the gadget
host: test-usb (tools/usb/testusb.c)
The function is provided by usb_f_uac1_legacy.ko module.
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.
device: run the gadget
host:
aplay -l # should list our USB Audio Gadget
The function is provided by usb_f_uac2.ko module.
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 capture sampling rate c_ssize capture sample size (bytes) p_chmask playback channel mask p_srate playback sampling rate p_ssize playback sample size (bytes) req_number the number of pre-allocated request for both capture and playback
The attributes have sane default values.
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
The function is provided by usb_f_uvc.ko module.
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
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 inverval 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
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
The function is provided by usb_f_printer.ko module.
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
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.
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.
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 capture sampling rate c_ssize capture sample size (bytes) p_chmask playback channel mask p_srate playback sampling rate p_ssize playback sample size (bytes) req_number the number of pre-allocated request for both capture and playback
The attributes have sane default values.
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