term% ls -F
term% cat index.txt
USB(4)                     Kernel Interfaces Manual                     USB(4)

       audio, ccid, disk, ether, kb, print, probe, serial, usbeject, usbfat: -
       Universal Serial Bus device drivers

       usb/kb [ -dkm ] [ -a accel ] [ dev ...  ]

       usb/disk [ -Dd ] [ -m mnt ] [ -s srv ] [ dev ...  ]

       usbfat: [ disk ...  ]

       usbeject [ disk ...  ]

       usb/audio [ -dpV ] [ -m mnt ] [ -s srv ] [ -v vol ] [ dev ]

       usb/ether [ -Dd ] [ -m mnt ] [ -s srv ] [ dev ...  ]

       usb/serial [ -Dd ] [ -m mnt ] [ -s srv ] [ dev ...  ]

       usb/print [ -d ] [ dev ...  ]

       usb/ccid [ -d ] usb/probe

       These programs drive USB devices of specific classes via usb(3).   Usu‐
       ally  they  are started by usbd(4) upon attachment of the device to the
       bus.  Less often, users start them  manually,  depending  on  usbd(4)'s
       configuration.  Usually, kb and disk are started by usbd and other pro‐
       grams are started by hand.

       Without arguments, the drivers handle all the devices (of the appropri‐
       ate  USB class) found on the bus.  To make a driver handle only certain
       devices, supply as arguments the paths for the directories of  the  de‐
       vices (actually of their zero endpoints).

       Drivers  that provide file systems accept options -s and -m to instruct
       them to post a 9P connection at srv(3) with the given  name  and/or  to
       mount themselves at mnt.  When embedded into usbd these options may not
       be used.  In this case, the file tree supplied by the device driver  is
       available  through the file system provided by usbd, usually mounted at
       /dev and reachable through the 9P connection posted at /srv/usb.

       Options -d and -D present on most drivers trigger debug diagnostics and
       file  system debugging diagnostics.  Repeating any one of these may in‐
       crease verbosity.

       To help locate devices of interest, probe lists  all  the  USB  devices
       available, including those with no driver started.

   Keyboards and mice
       Kb supports USB keyboards and mice either as separate USB devices or as
       a single combined USB device.  Scan codes from the keyboard are sent to
       /dev/kbin  to  let  the  kernel process them.  Mouse events are sent to
       /dev/mousein in the same way.

       The following options are understood:

       -a     Accelerate the mouse to level n (similar  to  the  kernel  mouse
              driver acceleration).

       -k     Serve just the keyboard (and not the mouse).

       -m     Serve just the mouse (and not the keyboard).

       Disk  configures  and  manages  USB mass storage devices. It provides a
       file system (usually seen at /dev)  that  includes  one  directory  per
       storage device, named sdUN.M in correspondence with the usb device num‐
       ber and the storage unit number (or LUN).  For example, LUN number 2 on
       /dev/usb/ep3.0 can be accessed through /dev/sdU3.2.

       The  storage device directory contains the usual files served by sd(3):
       data, raw, and ctl.

       The ctl file supplies the device geometry when read.

       The script usbfat: mounts the FAT file systems in the DOS partitions of
       the  named  disks;  if  none,  it  mounts  those  file systems found at
       /dev/sdU*.*/data.  When more than one partition is found, a  suffix  is
       appended to the disk name to identify the partition number.  The script
       usbeject undoes the effect. If no argument is given,  it  unmounts  all
       USB  disks. An argument sdUN unmounts all partitions from disk with USB
       target N.

       Print provides a single file can be written to print on a USB  printer.
       Options  are  similar  to  those  of  disk.   The file is also bound at
       /dev/lp as is customary.

   Ethernet adapters
       Ether provides a file interface similar to that of  ether(3)  for  each
       USB  Ethernet adapter found.  The name of an Ethernet device is etherUN
       where N is the device name.  When started manually, the file  interface
       is mounted at /net as is customary.

   Serial and JTAG ports
       Serial  provides  a file system (usually mounted at /dev) that includes
       one directory per USB serial port, named eiaUN or eiaUN.M.  In this di‐
       rectory  there  are  two  files,  eiaU, similar to eiaN in uart(3), and
       eiaUctl, which admits writes in the same format as eiaNctl in  uart(3).
       Reading  from eiaUctl gives the serial port's settings in the same for‐
       mat as eiaNstatus in uart(3).  Options are similar to those of disk.

       JTAG ports are similar but the files are named jtag and jtagctl.

   Audio devices
       Usbaudio configures and manages a USB audio device.   It  implements  a
       file system, normally mounted on /dev, but this can be changed with -m,
       containing files volume, audioctl, audio, and audioin.  The names  vol‐
       ume  and  audio  maintain  backward compatibility with the Soundblaster

       The -V option (verbose) causes audio to print information about the de‐
       vice  on startup.  The -s option specifies a name for a file descriptor
       to be posted in /srv.  The -v options sets initial volume.

       Reading volume or audioctl yields the device's settings.  The data for‐
       mat  of  volume is compatible with the Soundblaster and produces output
       in this format:

              audio out 65
              treb out 0
              bass out 0
              speed out 44100

       This file can be written using the same syntax.   The  keyword  may  be
       omitted.   Settings  are  given as percentages of the range, except for
       speed which is in Hz.

       The file audioctl provides more information, using up to 6  columns  of
       12  characters each.  From left to right, the fields are: control name,
       in or out, current  value,  minimum  value,  maximum,  and  resolution.
       There  are 3, 5, or 6 columns present.  Maxima and resolution are omit‐
       ted when they are not available or not applicable.  The resolution  for
       speed  is reported as 1 (one) if the sampling frequency is continuously
       variable.  It is absent if it is settable at a fixed number of discrete
       values only.

       When  all  values from audioctl have been read, a zero-length buffer is
       returned (the usual end-of-file indication).   A  new  read  will  then
       block until one of the settings changes, then report its new value.

       The file audioctl can be written like volume.

       Audio  data is written to audio and read from audioin.  The data format
       is little-endian, samples ordered primarily by time and secondarily  by
       channel.   Samples  occupy  the minimum integral number of bytes.  Read
       and write operations of arbitrary size are allowed.

       Ccid discovers and configures SIM or SAM cards using the CCID standard.
       It provides a file system (usually mounted at /dev) that includes three
       files, ctl, raw and rpc.  Reading from ctl a description of the  smart‐
       card  reader  capabilities is printed.  raw is just intended for debug‐
       ging.  Reads and writes to the raw file send and receive raw CCID pack‐
       ets.  Smart cards identify themselves by giving out an ATR, an array of
       characters describing the card uniquely.  Users of the driver write the
       ATR to the rpc file and are blocked until a card with that ATR is seen.
       From then on they can do ICC RPCs using  whatever  language  the  smart
       card speaks. A small write cancels an outstanding RPC.

       The  driver  takes  care  of powering the card adequately, based on its
       ATR, and tunnelling the RPCs through the USB device.  Only  slot  0  is

       When  the smartcard disappears, all reads and write fail until the file
       is reopened and a new ATR is written to it.


       kbin(3), mouse(3), sd(3), uart(3), usb(3), usbd(4), partfs(8)

       The various device drivers are generic USB drivers and  may  work  only
       for certain devices on each class.

       USB ATA storage devices are not supported.

       The Ethernet device works only for certain ASIX-based cards and for CDC
       devices.  Both the Ethernet and printer drivers have  not  been  tested
       and it is likely they will fail.

       The  serial  driver works only for the Prolific chip and Ftdi, and con‐
       trol of the dcd and dsr signals and some  of  the  extra  features  are
       unimplemented.   For  Ftdi,  only the Sheevaplug and Guruplug have been
       tried.  There is support for the EHCI debug port, but it loses bytes.