1.\" Copyright (c) 1997, 1998 Nick Hibma <n_hibma@FreeBSD.org> 2.\" Copyright (c) 2008 Hans Petter Selasky. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd November 26, 2013 28.Dt USB 4 29.Os 30.Sh NAME 31.Nm usb 32.Nd Universal Serial Bus 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following line in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device usb" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45usb_load="YES" 46.Ed 47.Sh USERLAND PROGRAMMING 48USB functions can be accessed from userland through the libusb library. 49See 50.Xr libusb 3 51for more information. 52.Sh DESCRIPTION 53.Fx 54provides machine-independent bus support and drivers for 55.Tn USB 56devices in host and device side mode. 57.Pp 58The 59.Nm 60driver has three layers: 61.Bl -tag -width 6n -offset indent 62.It USB Controller (Bus) 63.It USB Device 64.It USB Driver 65.El 66.Pp 67The controller attaches to a physical bus 68like 69.Xr pci 4 . 70The 71.Tn USB 72bus attaches to the controller, and the root hub attaches 73to the controller. 74Any devices attached to the bus will attach to the root hub 75or another hub attached to the 76.Tn USB 77bus. 78.Pp 79The 80.Nm uhub 81device will always be present as it is needed for the 82root hub. 83.Sh INTRODUCTION TO USB 84The 85.Tn USB 86is a system where external devices can be connected to a PC. 87The most common USB speeds are: 88.Bl -tag -width 6n -offset indent 89.It Low Speed (1.5MBit/sec) 90.It Full Speed (12MBit/sec) 91.It High Speed (480MBit/sec) 92.El 93.Pp 94Each 95.Tn USB 96has a USB controller that is the master of the bus. 97The physical communication is simplex which means the host controller only communicates with one USB device at a time. 98.Pp 99There can be up to 127 devices connected to an USB HUB tree. 100The addresses are assigned 101dynamically by the host when each device is attached to the bus. 102.Pp 103Within each device there can be up to 16 endpoints. 104Each endpoint 105is individually addressed and the addresses are static. 106Each of these endpoints will communicate in one of four different modes: 107.Em control , isochronous , bulk , 108or 109.Em interrupt . 110A device always has at least one endpoint. 111This endpoint has address 0 and is a control 112endpoint and is used to give commands to and extract basic data, 113such as descriptors, from the device. 114Each endpoint, except the control endpoint, is unidirectional. 115.Pp 116The endpoints in a device are grouped into interfaces. 117An interface is a logical unit within a device; e.g.\& 118a compound device with both a keyboard and a trackball would present 119one interface for each. 120An interface can sometimes be set into different modes, 121called alternate settings, which affects how it operates. 122Different alternate settings can have different endpoints 123within it. 124.Pp 125A device may operate in different configurations. 126Depending on the 127configuration, the device may present different sets of endpoints 128and interfaces. 129.Pp 130The bus enumeration of the 131.Tn USB 132bus proceeds in several steps: 133.Bl -enum 134.It 135Any interface specific driver can attach to the device. 136.It 137If none is found, generic interface class drivers can attach. 138.El 139.Sh SEE ALSO 140The 141.Tn USB 142specifications can be found at: 143.Pp 144.D1 Pa http://www.usb.org/developers/docs/ 145.Pp 146.Xr libusb 3 , 147.Xr usbdi 4 , 148.Xr aue 4 , 149.Xr axe 4 , 150.Xr axge 4 , 151.Xr cue 4 , 152.Xr ehci 4 , 153.Xr kue 4 , 154.Xr mos 4 , 155.Xr ohci 4 , 156.Xr pci 4 , 157.Xr rue 4 , 158.Xr ucom 4 , 159.Xr udav 4 , 160.Xr uhci 4 , 161.Xr uhid 4 , 162.Xr ukbd 4 , 163.Xr ulpt 4 , 164.Xr umass 4 , 165.Xr ums 4 , 166.Xr uplcom 4 , 167.Xr urio 4 , 168.Xr uvscom 4 , 169.Xr usbconfig 8 , 170.Xr xhci 4 171.Sh STANDARDS 172The 173.Nm 174module complies with the USB 2.0 standard. 175.Sh HISTORY 176The 177.Nm 178module has been inspired by the NetBSD USB stack initially written by 179Lennart Augustsson. The 180.Nm 181module was written by 182.An Hans Petter Selasky Aq hselasky@FreeBSD.org . 183