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 April 29, 2017 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 root hub. 82.Sh INTRODUCTION TO USB 83The 84.Tn USB 85is a system where external devices can be connected to a PC. 86The most common USB speeds are: 87.Bl -tag -width 6n -offset indent 88.It Low Speed (1.5MBit/sec) 89.It Full Speed (12MBit/sec) 90.It High Speed (480MBit/sec) 91.El 92.Pp 93Each 94.Tn USB 95has a USB controller that is the master of the bus. 96The physical communication is simplex which means the host controller only 97communicates 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 dynamically by the host when each device is 101attached to the bus. 102.Pp 103Within each device there can be up to 16 endpoints. 104Each endpoint is individually addressed and the addresses are static. 105Each of these endpoints will communicate in one of four different modes: 106.Em control , isochronous , bulk , 107or 108.Em interrupt . 109A device always has at least one endpoint. 110This endpoint has address 0 and is a control endpoint and is used to give 111commands to and extract basic data, such as descriptors, from the device. 112Each endpoint, except the control endpoint, is unidirectional. 113.Pp 114The endpoints in a device are grouped into interfaces. 115An interface is a logical unit within a device, e.g., a compound device with 116both a keyboard and a trackball, would present one interface for each. 117An interface can sometimes be set into different modes, called alternate 118settings, which affects how it operates. 119Different alternate settings can have different endpoints within it. 120.Pp 121A device may operate in different configurations. 122Depending on the configuration, the device may present different sets of 123endpoints and interfaces. 124.Pp 125The bus enumeration of the 126.Tn USB 127bus proceeds in several steps: 128.Bl -enum 129.It 130Any interface specific driver can attach to the device. 131.It 132If none is found, generic interface class drivers can attach. 133.El 134.Sh SEE ALSO 135The 136.Tn USB 137specifications can be found at: 138.Pp 139.D1 Pa http://www.usb.org/developers/docs/ 140.Pp 141.Xr libusb 3 , 142.Xr aue 4 , 143.Xr axe 4 , 144.Xr axge 4 , 145.Xr cue 4 , 146.Xr ehci 4 , 147.Xr kue 4 , 148.Xr mos 4 , 149.Xr ohci 4 , 150.Xr pci 4 , 151.Xr rue 4 , 152.Xr ucom 4 , 153.Xr udav 4 , 154.Xr uhci 4 , 155.Xr uhid 4 , 156.Xr ukbd 4 , 157.Xr ulpt 4 , 158.Xr umass 4 , 159.Xr ums 4 , 160.Xr uplcom 4 , 161.Xr urio 4 , 162.Xr uvscom 4 , 163.Xr xhci 4 164.Xr usbconfig 8 , 165.Xr usbdi 9 , 166.Sh STANDARDS 167The 168.Nm 169module complies with the USB 2.0 standard. 170.Sh HISTORY 171The 172.Nm 173module has been inspired by the 174.Nx 175USB stack initially written by 176.An Lennart Augustsson . 177The 178.Nm 179module was written by 180.An Hans Petter Selasky Aq Mt hselasky@FreeBSD.org . 181