.\" $OpenBSD: usb.4,v 1.13 2001/10/04 10:28:20 wilfried Exp $ .\" $NetBSD: usb.4,v 1.15 1999/07/29 14:20:32 augustss Exp $ .\" .\" Copyright (c) 1999 The NetBSD Foundation, Inc. .\" All rights reserved. .\" .\" This code is derived from software contributed to The NetBSD Foundation .\" by Lennart Augustsson. .\" .\" 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. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the NetBSD .\" Foundation, Inc. and its contributors. .\" 4. Neither the name of The NetBSD Foundation nor the names of its .\" contributors may be used to endorse or promote products derived .\" from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. .\" .Dd July 12, 1998 .Dt USB 4 .Os .Sh NAME .Nm usb .Nd introduction to Universal Serial Bus support .Sh SYNOPSIS .Cd "uhci* at pci? function ?" .Cd "ohci* at pci? function ?" .Cd "usb* at uhci?" .Cd "usb* at ohci?" .Cd "uhub* at usb?" .Cd "uhub* at uhub? port ? configuration ? interface ? vendor ? product ? release ?" .Cd "XX* at uhub? port ? configuration ? interface ? vendor ? product ? release ?" .Pp .Cd "#include " .Cd "#include " .Sh DESCRIPTION .Ox provides machine-independent bus support and drivers for Universal Serial Bus .Pq Tn USB devices. .Pp The .Ox .Nm driver has three layers (like .Xr scsi 4 and .Xr pcmcia 4 ) : the controller, the bus, and the device layer. 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. Further devices, which may include further hubs, attach to other hubs. The attachment forms the same tree structure as the physical .Tn USB device tree. For each .Tn USB device there may be additional drivers attached to it. .Pp The .Cm uhub device controls .Tn USB hubs and must always be present since there is at least one root hub in any .Tn USB system. .Sh SUPPORTED DEVICES .Ox includes machine-independent .Tn USB drivers, sorted by driver name: .Pp .Bl -tag -width speakerxx -offset ind -compact .It Xr aue 4 AN986 Pegasus-based Ethernet interfaces. .It Xr cue 4 CATC USB-EL1201A-based Ethernet interfaces. .It Xr kue 4 Kawasaki LSI KL5KUSB101B-based Ethernet interfaces. .It Xr uaudio 4 Audio devices. .It Xr ugen 4 Generic driver for unknown .Tn USB devices. .It Xr uhid 4 Generic driver for Human Interface Devices. .It Xr ulpt 4 .Tn USB Printers. .It Xr umass 4 .Tn USB Mass Storage Devices, e.g., external disk drives. .It Xr umodem 4 .Tn USB Modems. .El .Sh INTRODUCTION TO USB The .Tn USB is a 12 Mb/s serial bus (1.5 Mb/s for low speed devices). Each .Tn USB has a host controller that is the master of the bus; all other devices on the bus only speak when spoken to. .Pp There can be up to 127 devices (apart from the host controller) on a bus, each with its own address. 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: control, isochronous, bulk, or interrupt. A device always has at least one endpoint. This is a control endpoint at address 0 and is used to give commands to the device 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 Each device located on a hub has several .Xr config 8 locators: .Pp .Bl -tag -width configuration -compact .It Cd port Number of the port on closest upstream hub. .It Cd configuration Configuration the device must be in for this driver to attach. This locator does not set the configuration; it is iterated by the bus enumeration. .It Cd interface Interface number within a device that an interface driver attaches to. .It Cd vendor 16-bit vendor ID of the device. .It Cd product 16-bit product ID of the device. .It Cd release 16-bit release (revision) number of the device. .El .Pp The first locator can be used to pin down a particular device according to its physical position in the device tree. The last three locators can be used to pin down a particular device according to what device it actually is. .Pp The bus enumeration of the .Tn USB bus proceeds in several steps: .Bl -enum .It Any device-specific driver can attach to the device. .It If none is found, any device class specific driver can attach. .It If none is found, all configurations are iterated over. For each configuration all the interface are iterated over and interface drivers can attach. If any interface driver attached in a certain configuration the iteration over configurations is stopped. .It If still no drivers have been found, the generic .Tn USB driver can attach. .El .Sh USB CONTROLLER INTERFACE Use the following to get access to the .Tn USB specific structures and defines. .Bd -literal #include .Ed .Pp The .Pa /dev/usbN device can be opened and a few operations can be performed on it. The .Xr poll 2 system call will say that I/O is possible on the controller device when a .Tn USB device has been connected or disconnected to the bus. .Pp The following .Xr ioctl 2 commands are supported on the controller device: .Bl -tag -width xxxxxx .\" .It Dv USB_DISCOVER .\" This command will cause a complete bus discovery to be initiated. .\" If any devices attached or detached from the bus they will be .\" processed during this command. .\" This is the only way that new devices are found on the bus. .It Dv USB_DEVICEINFO Fa "struct usb_device_info" This command can be used to retrieve some information about a device on the bus. The .Va addr field should be filled before the call and the other fields will be filled by information about the device on that address. Should no such device exist an error is reported. .Bd -literal struct usb_device_info { uByte addr; /* device address */ char product[USB_MAX_STRING_LEN]; char vendor[USB_MAX_STRING_LEN]; char release[8]; uByte class; uByte config; uByte lowspeed; int power; int nports; uByte ports[16]; #define USB_PORT_ENABLED 0xff #define USB_PORT_SUSPENDED 0xfe #define USB_PORT_POWERED 0xfd #define USB_PORT_DISABLED 0xfc }; .Ed .Pp The .Va product , .Va vendor , and .Va release fields contain self-explanatory descriptions of the device. .Pp The .Va class field contains the device class. .Pp The .Va config field shows the current configuration of the device. .Pp The .Va lowspeed field is set if the device is a .Tn USB low speed device. .Pp The .Va power field shows the power consumption in milli-amps drawn at 5 volts, or zero if the device is self powered. .Pp If the device is a hub the .Va nports field is non-zero and the .Va ports field contains the addresses of the connected devices. If no device is connected to a port one of the .Va USB_PORT_* values indicates its status. .It Dv USB_DEVICESTATS Fa "struct usb_device_stats" This command retrieves statistics about the controller. .Bd -literal struct usb_device_stats { u_long requests[4]; }; .Ed .Pp The .Va requests field is indexed by the transfer kind, i.e. .Va UE_* , and indicates how many transfers of each kind that has been completed by the controller. .It Dv USB_REQUEST Fa "struct usb_ctl_request" This command can be used to execute arbitrary requests on the control pipe. This is .Em DANGEROUS and should be used with great care since it can destroy the bus integrity. .El .Pp The include file .Aq Pa dev/usb/usb.h contains definitions for the types used by the various .Xr ioctl 2 calls. The naming convention of the fields for the various .Tn USB descriptors exactly follows the naming in the .Tn USB specification. Byte sized fields can be accessed directly, but word (16-bit) sized fields must be access by the .Fn UGETW field and .Fn USETW field value macros to handle byte order and alignment properly. .Pp The include file .Aq Pa dev/usb/usbhid.h similarly contains the definitions for Human Interface Devices .Pq Tn HID . .Sh SEE ALSO .Xr cardbus 4 , .Xr intro 4 , .Xr isa 4 , .Xr isapnp 4 , .Xr pci 4 , .Xr pcmcia 4 , .Xr usbdevs 8 .Pp The .Tn USB specifications can be found at: .Pp .Dl http://www.usb.org/developers/docs.html .Sh HISTORY The .Nm driver appeared in .Ox 2.6 . .Sh BUGS There should be a serial number locator, but .Ox does not have string valued locators.