299 lines
8.4 KiB
Groff
299 lines
8.4 KiB
Groff
.\" Copyright (c) 1997, 1998
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.\" Nick Hibma <hibma@skylink.it>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Bill Paul.
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.\" 4. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY NICK HIBMA AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL NICK HIBMA OR THE VOICES IN HIS HEAD
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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.\" THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 21, 1999
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.Dt USB 4
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.Os FreeBSD
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.Sh NAME
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.Nm usb
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.Nd Universal Serial Bus
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.Sh SYNOPSIS
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.Cd "controller usb0"
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.Sh DESCRIPTION
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.Fx
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provides machine-independent bus support and drivers for
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.Tn USB
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devices.
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.Pp
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The
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.Nm
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driver has three layers: the controller, the bus, and the
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device layer. The controller attaches to a physical bus
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(like
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.Xr pci 4 ).
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The
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.Tn USB
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bus attaches to the controller and the root hub attaches
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to the controller.
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Any devices attached to the bus will attach to the root hub
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or another hub attached to the USB bus.
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.Pp
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The
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.Nm uhub
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device will always be present as it is needed for the
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root hub.
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.Pp
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.Sh INTRODUCTION TO USB
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The
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.Tn USB
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is a 12 Mb/s serial bus (1.5 Mb/s for low speed devices).
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Each
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.Tn USB
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has a host controller that is the master of the bus;
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all other devices on the bus only speak when spoken to.
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.Pp
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There can be up to 127 devices (apart from the host controller)
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on a bus, each with its own address.
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The addresses are assigned
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dynamically by the host when each device is attached to the bus.
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.Pp
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Within each device there can be up to 16 endpoints.
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Each endpoint
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is individually addressed and the addresses are static.
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Each of these endpoints will communicate in one of four different modes:
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control, isochronous, bulk, or interrupt.
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A device always has at least one endpoint.
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This endpoint has address 0 and is a control
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endpoint and is used to give commands to and extract basic data,
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such as descriptors, from the device.
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Each endpoint, except the control endpoint, is unidirectional.
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.Pp
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The endpoints in a device are grouped into interfaces.
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An interface is a logical unit within a device; e.g.
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a compound device with both a keyboard and a trackball would present
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one interface for each.
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An interface can sometimes be set into different modes,
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called alternate settings, which affects how it operates.
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Different alternate settings can have different endpoints
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within it.
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.Pp
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A device may operate in different configurations.
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Depending on the
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configuration the device may present different sets of endpoints
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and interfaces.
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.Pp
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Each device located on a hub has several
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.Xr config 8
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locators:
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.Bl -tag -compact -width xxxxxx
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.It Cd port
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this is the number of the port on the closest upstream hub.
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.It Cd configuration
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this is the configuration the device must be in for this driver to attach.
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This locator does not set the configuration; it is iterated by the bus
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enumeration.
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.It Cd interface
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this is the interface number within a device that an interface driver
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attaches to.
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.El
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.Pp
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The bus enumeration of the
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.Tn USB
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bus proceeds in several steps:
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.Bl -enum
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.It
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Any device specific driver can to attach to the device.
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.It
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If none is found, any device class specific driver can attach.
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.It
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If none is found, all configurations are iterated over.
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For each configuration all the interface are iterated over and interface
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drivers can attach.
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If any interface driver attached in a certain
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configuration the iteration over configurations is stopped.
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.It
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If still no drivers have been found, the generic
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.Tn USB
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driver can attach.
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.El
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.Sh USB CONTROLLER INTERFACE
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Use the following to get access to the
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.Tn USB
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specific structurs and defines.
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.Bd -literal
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#include <sys/dev/usb.h>
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.Ed
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.Pp
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The
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.Pa /dev/usbN
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can be opened and a few operations can be performed on it.
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The
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.Xr poll 2
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system call will say that I/O is possible on the controller device when a
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.Tn USB
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device has been connected or disconnected to the bus.
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.Pp
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The following
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.Xr ioctl 2
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commands are supported on the controller device:
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.Bl -tag -width xxxxxx
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.It Dv USB_DISCOVER
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This command will cause a complete bus discovery to be initiated.
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If any devices attached or detached from the bus they will be
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processed during this command.
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This is the only way that new devices are found on the bus.
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.It Dv USB_DEVICEINFO Fa "struct usb_device_info"
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This command can be used to retrieve some information about a device
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on the bus.
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The
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.Va addr
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field should be filled before the call and the other fields will
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be filled by information about the device on that address.
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Should no such device exist an error is reported.
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.Bd -literal
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struct usb_device_info {
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uByte addr; /* device address */
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char product[USB_MAX_STRING_LEN];
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char vendor[USB_MAX_STRING_LEN];
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char revision[8];
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uByte class;
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uByte config;
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uByte lowspeed;
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int power;
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int nports;
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uByte ports[16];
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#define USB_PORT_ENABLED 0xff
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#define USB_PORT_SUSPENDED 0xfe
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#define USB_PORT_POWERED 0xfd
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#define USB_PORT_DISABLED 0xfc
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};
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.Ed
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.Pp
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The
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.Va product ,
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.Va vendor ,
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and
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.Va revision
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fields contain self-explanatory descriptions of the device.
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.Pp
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The
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.Va class
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field contains the device class.
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.Pp
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The
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.Va config
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field shows the current configuration of the device.
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.Pp
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The
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.Va lowspeed
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field
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is set if the device is a
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.Tn USB
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low speed device.
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.Pp
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The
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.Va power
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field shows the power consumption in milli-amps drawn at 5 volts,
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or zero if the device is self powered.
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.Pp
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If the device is a hub the
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.Va nports
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field is non-zero and the
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.Va ports
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field contains the addresses of the connected devices.
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If no device is connected to a port one of the
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.Va USB_PORT_*
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values indicates its status.
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.It Dv USB_DEVICESTATS Fa "struct usb_device_stats"
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This command retrieves statistics about the controller.
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.Bd -literal
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struct usb_device_stats {
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u_long requests[4];
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};
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.Ed
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.Pp
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The
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.Va requests
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field is indexed by the transfer kind, i.e.
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.Va UE_* ,
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and indicates how many transfers of each kind that has been completed
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by the controller.
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.It Dv USB_REQUEST Fa "struct usb_ctl_request"
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This command can be used to execute arbitrary requests on the control pipe.
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This is
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.Em DANGEROUS
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and should be used with great care since it
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can destroy the bus integrity.
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.El
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.Pp
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The include file
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.Aq Pa dev/usb/usb.h
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contains definitions for the types used by the various
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.Xr ioctl 2
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calls.
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The naming convention of the fields for the various
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.Tn USB
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descriptors exactly follows the naming in the
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.Tn USB
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specification.
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Byte sized fields can be accessed directly, but word (16 bit)
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sized fields must be access by the
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.Fn UGETW field
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and
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.Fn USETW field value
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macros to handle byte order and alignment properly.
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.Pp
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The include file
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.Aq Pa dev/usb/usbhid.h
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similarly contains the definitions for
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Human Interface Devices
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.Pq Tn HID .
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.Sh SEE ALSO
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The
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.Tn USB
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specifications can be found at
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.Dv http://www.usb.org/developers/docs.htm .
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.Pp
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.Xr pci 4 ,
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.Xr ohci 4 ,
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.Xr ugen 4 ,
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.Xr uhci 4 ,
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.Xr uhid 4 ,
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.Xr ukbd 4 ,
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.Xr ulpt 4 ,
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.Xr ums 4 ,
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.Xr usbd 8 ,
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.Xr usbdevs 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 3.0 .
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.Sh AUTHORS
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The
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.Nm
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driver was written by
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.An Lennart Augustsson Aq augustss@carlstedt.se
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for the
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.Nx
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project.
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