118 lines
4.0 KiB
Groff
118 lines
4.0 KiB
Groff
.\"
|
|
.\" Copyright (c) 2003 Marcel Moolenaar
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd August 25, 2003
|
|
.Dt UART 4
|
|
.Os
|
|
.\"
|
|
.Sh NAME
|
|
.Nm uart
|
|
.Nd driver for Universal Asynchronous Receiver/Transmitter (UART) devices
|
|
.\"
|
|
.Sh SYNOPSIS
|
|
.Cd "device uart"
|
|
.Pp
|
|
.Cd "device puc"
|
|
.Cd "device uart"
|
|
.\"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
device driver provides support for various classes of UARTs implementing the
|
|
EIA RS-232C (CCITT V.24) serial communications interface.
|
|
Each such interface is controlled by a seperate and independent instance of
|
|
the
|
|
.Nm
|
|
driver.
|
|
The primary support for devices that contain multiple serial interfaces or
|
|
that contain other functionality besides one or more serial interfaces is
|
|
provided by the
|
|
.Xr puc 4
|
|
device driver.
|
|
However, the serial interfaces of those devices that are managed by the
|
|
.Xr puc 4
|
|
driver are controlled by the
|
|
.Nm
|
|
driver.
|
|
As such, the
|
|
.Xr puc 4
|
|
driver provides umbrella functionality for the
|
|
.Nm
|
|
driver and hides the complexities that are inherent when elementary components
|
|
are packaged together.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
driver has a modular design to allow it to be used on differing hardware and
|
|
for various purposes.
|
|
In the following sections the components are discussed in detail.
|
|
Options are described in the section that covers the component to which each
|
|
option applies.
|
|
.\"
|
|
.Ss CORE COMPONENT
|
|
At the heart of the
|
|
.Nm
|
|
driver is the core component.
|
|
It contains the bus attachments and the low-level interrupt handler.
|
|
.\"
|
|
.Ss HARDWARE DRIVERS
|
|
The core component and the kernel interfaces talk to the hardware through the
|
|
hardware interface.
|
|
This interface serves as an abstraction of the hardware and allows varying
|
|
UARTs to be used for serial communications.
|
|
.\"
|
|
.Ss SYSTEM DEVICES
|
|
System devices are UARTs that have a special purpose by way of hardware
|
|
design or software setup.
|
|
For example, Sun UltraSparc machines use UARTs as their keyboard interface.
|
|
Such an UART cannot be used for general purpose communications.
|
|
Likewise, when the kernel is configured for a serial console, the
|
|
corresponding UART will in turn be a system device so that the kernel can
|
|
output boot messages early on in the boot process.
|
|
.\"
|
|
.Ss KERNEL INTERFACES
|
|
The last but not least of the components is the kernel interface.
|
|
This component ultimately determines how the UART is made visible to the
|
|
kernel in particular and to users in general.
|
|
The default kernel interface is the TTY interface.
|
|
This allows the UART to be used for terminals, modems and serial line IP
|
|
applications.
|
|
System devices, with the notable exception of serial consoles, generally
|
|
have specialized kernel interfaces.
|
|
.\"
|
|
.Sh SEE ALSO
|
|
.Xr puc 4
|
|
.\"
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
device driver first appeared in
|
|
.Fx 5.2 .
|
|
.Sh AUTHORS
|
|
This manual page was written by
|
|
.An Marcel Moolenaar Aq marcel@xcllnt.net .
|