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.Dd September 7, 2020 26.Dt USB 4 27.Os 28.Sh NAME 29.Nm usb 30.Nd Universal Serial Bus 31.Sh SYNOPSIS 32To compile this driver into the kernel, 33place the following line in your 34kernel configuration file: 35.Bd -ragged -offset indent 36.Cd "device usb" 37.Ed 38.Pp 39Alternatively, to load the driver as a 40module at boot time, place the following line in 41.Xr loader.conf 5 : 42.Bd -literal -offset indent 43usb_load="YES" 44.Ed 45.Sh USERLAND PROGRAMMING 46USB functions can be accessed from userland through the libusb library. 47See 48.Xr libusb 3 49for more information. 50.Sh DESCRIPTION 51.Fx 52provides machine-independent bus support and drivers for 53USB devices in host and device side mode. 54.Pp 55The 56.Nm 57driver has three layers: 58.Bl -tag -width 6n -offset indent 59.It USB Controller (Bus) 60.It USB Device 61.It USB Driver 62.El 63.Pp 64The controller attaches to a physical bus 65like 66.Xr pci 4 . 67The USB bus attaches to the controller, and the root hub attaches 68to the controller. 69Any devices attached to the bus will attach to the root hub 70or another hub attached to the USB bus. 71.Pp 72The 73.Nm uhub 74device will always be present as it is needed for the root hub. 75.Sh INTRODUCTION TO USB 76The USB is a system where external devices can be connected to a PC. 77The most common USB speeds are: 78.Bl -tag -width 6n -offset indent 79.It Low Speed (1.5 MBit/sec) 80.It Full Speed (12 MBit/sec) 81.It High Speed (480 MBit/sec) 82.It SuperSpeed (5 GBit/sec) 83.El 84.Pp 85Each USB has a USB controller that is the master of the bus. 86The physical communication is simplex which means the host controller only 87communicates with one USB device at a time. 88.Pp 89There can be up to 127 devices connected to an USB HUB tree. 90The addresses are assigned dynamically by the host when each device is 91attached to the bus. 92.Pp 93Within each device there can be up to 16 endpoints. 94Each endpoint is individually addressed and the addresses are static. 95Each of these endpoints will communicate in one of four different modes: 96.Em control , isochronous , bulk , 97or 98.Em interrupt . 99A device always has at least one endpoint. 100This endpoint has address 0 and is a control endpoint and is used to give 101commands to and extract basic data, such as descriptors, from the device. 102Each endpoint, except the control endpoint, is unidirectional. 103.Pp 104The endpoints in a device are grouped into interfaces. 105An interface is a logical unit within a device, e.g., a compound device with 106both a keyboard and a trackball, would present one interface for each. 107An interface can sometimes be set into different modes, called alternate 108settings, which affects how it operates. 109Different alternate settings can have different endpoints within it. 110.Pp 111A device may operate in different configurations. 112Depending on the configuration, the device may present different sets of 113endpoints and interfaces. 114.Pp 115The bus enumeration of the USB bus proceeds in several steps: 116.Bl -enum 117.It 118Any interface specific driver can attach to the device. 119.It 120If none is found, generic interface class drivers can attach. 121.El 122.Sh SYSCTL VARIABLES 123The following variables are available as both 124.Xr sysctl 8 125variables and 126.Xr loader 8 127tunables: 128.Bl -tag -width indent 129.It Va hw.usb.debug 130Debug output level, where 0 is debugging disabled and larger values increase 131debug message verbosity. 132Default is 0. 133.El 134.Sh SEE ALSO 135The USB specifications can be found at: 136.Pp 137.D1 Pa https://www.usb.org/documents 138.Pp 139.Xr libusb 3 , 140.Xr aue 4 , 141.Xr axe 4 , 142.Xr axge 4 , 143.Xr cue 4 , 144.Xr ehci 4 , 145.Xr kue 4 , 146.Xr mos 4 , 147.Xr ohci 4 , 148.Xr pci 4 , 149.Xr rue 4 , 150.Xr ucom 4 , 151.Xr udav 4 , 152.Xr uhci 4 , 153.Xr uhid 4 , 154.Xr ukbd 4 , 155.Xr ulpt 4 , 156.Xr umass 4 , 157.Xr ums 4 , 158.Xr uplcom 4 , 159.Xr urio 4 , 160.Xr uvscom 4 , 161.Xr xhci 4 162.Xr usbconfig 8 , 163.Xr usbdi 9 164.Sh STANDARDS 165The 166.Nm 167module complies with the USB 3.0 standard. 168.Sh HISTORY 169The 170.Nm 171module has been inspired by the 172.Nx 173USB stack initially written by 174.An Lennart Augustsson . 175The 176.Nm 177module was written by 178.An Hans Petter Selasky Aq Mt hselasky@FreeBSD.org . 179