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 September 7, 2020 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 55USB devices in host and device side mode. 56.Pp 57The 58.Nm 59driver has three layers: 60.Bl -tag -width 6n -offset indent 61.It USB Controller (Bus) 62.It USB Device 63.It USB Driver 64.El 65.Pp 66The controller attaches to a physical bus 67like 68.Xr pci 4 . 69The USB bus attaches to the controller, and the root hub attaches 70to the controller. 71Any devices attached to the bus will attach to the root hub 72or another hub attached to the USB bus. 73.Pp 74The 75.Nm uhub 76device will always be present as it is needed for the root hub. 77.Sh INTRODUCTION TO USB 78The USB is a system where external devices can be connected to a PC. 79The most common USB speeds are: 80.Bl -tag -width 6n -offset indent 81.It Low Speed (1.5 MBit/sec) 82.It Full Speed (12 MBit/sec) 83.It High Speed (480 MBit/sec) 84.It SuperSpeed (5 GBit/sec) 85.El 86.Pp 87Each USB has a USB controller that is the master of the bus. 88The physical communication is simplex which means the host controller only 89communicates with one USB device at a time. 90.Pp 91There can be up to 127 devices connected to an USB HUB tree. 92The addresses are assigned dynamically by the host when each device is 93attached to the bus. 94.Pp 95Within each device there can be up to 16 endpoints. 96Each endpoint is individually addressed and the addresses are static. 97Each of these endpoints will communicate in one of four different modes: 98.Em control , isochronous , bulk , 99or 100.Em interrupt . 101A device always has at least one endpoint. 102This endpoint has address 0 and is a control endpoint and is used to give 103commands to and extract basic data, such as descriptors, from the device. 104Each endpoint, except the control endpoint, is unidirectional. 105.Pp 106The endpoints in a device are grouped into interfaces. 107An interface is a logical unit within a device, e.g., a compound device with 108both a keyboard and a trackball, would present one interface for each. 109An interface can sometimes be set into different modes, called alternate 110settings, which affects how it operates. 111Different alternate settings can have different endpoints within it. 112.Pp 113A device may operate in different configurations. 114Depending on the configuration, the device may present different sets of 115endpoints and interfaces. 116.Pp 117The bus enumeration of the USB bus proceeds in several steps: 118.Bl -enum 119.It 120Any interface specific driver can attach to the device. 121.It 122If none is found, generic interface class drivers can attach. 123.El 124.Sh SYSCTL VARIABLES 125The following variables are available as both 126.Xr sysctl 8 127variables and 128.Xr loader 8 129tunables: 130.Bl -tag -width indent 131.It Va hw.usb.debug 132Debug output level, where 0 is debugging disabled and larger values increase 133debug message verbosity. 134Default is 0. 135.El 136.Sh SEE ALSO 137The USB specifications can be found at: 138.Pp 139.D1 Pa https://www.usb.org/documents 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 3.0 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