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). Usually 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 programs are started by hand.

Without arguments, the drivers handle all the devices (of the appropriate USB class) found on the bus. To make a driver handle only certain devices, supply as arguments the paths for the directories of the devices (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 increase 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 number 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 directory 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 format 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 volume and audio maintain backward compatibility with the Soundblaster driver.

The –V option (verbose) causes audio to print information about the device 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 format 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 out 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 omitted 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 smartcard reader capabilities is printed. raw is just intended for debugging. Reads and writes to the raw file send and receive raw CCID packets. 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 supported.

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 control 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.

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