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.\" Copyright (c) 1997, 1998 Nick Hibma <n_hibma@FreeBSD.org>
.\" Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd May 20, 2009
.Dt USB 4
.Os
.Sh NAME
.Nm usb
.Nd Universal Serial Bus
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following line in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device usb"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
usb_load="YES"
.Ed
.Sh USERLAND PROGRAMMING
USB functions can be accessed from userland through the libusb library.
See
.Xr libusb 3
for more information.
.Sh DESCRIPTION
.Fx
provides machine-independent bus support and drivers for
.Tn USB
devices in host and device side mode.
.Pp
The
.Nm
driver has three layers:
.Bl -tag -width 6n -offset indent
.It USB Controller (Bus)
.It USB Device
.It USB Driver
.El
.Pp
The controller attaches to a physical bus
like
.Xr pci 4 .
The
.Tn USB
bus attaches to the controller, and the root hub attaches
to the controller.
Any devices attached to the bus will attach to the root hub
or another hub attached to the
.Tn USB
bus.
.Pp
The
.Nm uhub
device will always be present as it is needed for the
root hub.
.Sh INTRODUCTION TO USB
The
.Tn USB
is a system where external devices can be connected to a PC.
The most common USB speeds are:
.Bl -tag -width 6n -offset indent
.It Low Speed (1.5MBit/sec)
.It Full Speed (12MBit/sec)
.It High Speed (480MBit/sec)
.El
.Pp
Each
.Tn USB
has a USB controller that is the master of the bus.
The physical communication is simplex which means the host controller only communicates with one USB device at a time.
.Pp
There can be up to 127 devices connected to an USB HUB tree.
The addresses are assigned
dynamically by the host when each device is attached to the bus.
.Pp
Within each device there can be up to 16 endpoints.
Each endpoint
is individually addressed and the addresses are static.
Each of these endpoints will communicate in one of four different modes:
.Em control , isochronous , bulk ,
or
.Em interrupt .
A device always has at least one endpoint.
This endpoint has address 0 and is a control
endpoint and is used to give commands to and extract basic data,
such as descriptors, from the device.
Each endpoint, except the control endpoint, is unidirectional.
.Pp
The endpoints in a device are grouped into interfaces.
An interface is a logical unit within a device; e.g.\&
a compound device with both a keyboard and a trackball would present
one interface for each.
An interface can sometimes be set into different modes,
called alternate settings, which affects how it operates.
Different alternate settings can have different endpoints
within it.
.Pp
A device may operate in different configurations.
Depending on the
configuration, the device may present different sets of endpoints
and interfaces.
.Pp
The bus enumeration of the
.Tn USB
bus proceeds in several steps:
.Bl -enum
.It
Any interface specific driver can attach to the device.
.It
If none is found, generic interface class drivers can attach.
.El
.Sh SEE ALSO
The
.Tn USB
specifications can be found at:
.Pp
.D1 Pa http://www.usb.org/developers/docs/
.Pp
.Xr libusb 3 ,
.Xr usbdi 4 ,
.Xr aue 4 ,
.Xr axe 4 ,
.Xr cue 4 ,
.Xr ehci 4 ,
.Xr kue 4 ,
.Xr mos 4 ,
.Xr ohci 4 ,
.Xr pci 4 ,
.Xr rue 4 ,
.Xr ucom 4 ,
.Xr udav 4 ,
.Xr uhci 4 ,
.Xr uhid 4 ,
.Xr ukbd 4 ,
.Xr ulpt 4 ,
.Xr umass 4 ,
.Xr ums 4 ,
.Xr uplcom 4 ,
.Xr urio 4 ,
.Xr uvscom 4 ,
.Xr usbconfig 8 ,
.Xr xhci 4
.Sh STANDARDS
The
.Nm
module complies with the USB 2.0 standard.
.Sh HISTORY
The
.Nm
module has been inspired by the NetBSD USB stack initially written by
Lennart Augustsson. The
.Nm
module was written by
.An Hans Petter Selasky Aq hselasky@FreeBSD.org .
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