108 lines
3.4 KiB
Groff
108 lines
3.4 KiB
Groff
.\" Copyright (c) 1997
|
|
.\" Michael Smith
|
|
.\"
|
|
.\" 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 as
|
|
.\" the first lines of this file unmodified.
|
|
.\" 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 January 2, 1998
|
|
.Dt PPI 4
|
|
.Os FreeBSD
|
|
.Sh NAME
|
|
.Nm ppi
|
|
.Nd "user-space interface to ppbus parallel 'geek' port"
|
|
.Sh SYNOPSIS
|
|
.Cd "device ppi"
|
|
.Pp
|
|
Minor numbering: Unit numbers correspond directly to ppbus numbers.
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver provides a convenient means for user applications to manipulate the
|
|
state of the parallel port, enabling easy low-speed I/O operations without
|
|
the security problems inherent with the use of the
|
|
.Pa /dev/io
|
|
interface.
|
|
.Sh PROGRAMMING INTERFACE
|
|
.Pp
|
|
.Fd #include <dev/ppbus/ppi.h>
|
|
.Fd #include <dev/ppbus/ppbconf.h>
|
|
.Pp
|
|
All I/O on the
|
|
.Nm
|
|
interface is performed using
|
|
.Fn ioctl
|
|
calls. Each command takes a single
|
|
.Ft u_int8_t
|
|
argument, transferring one byte of data. The following commands are
|
|
available:
|
|
.Bl -tag -width indent
|
|
.It Dv PPIGDATA , PPISDATA
|
|
Get and set the contents of the data register.
|
|
.It Dv PPIGSTATUS , PPISSTATUS
|
|
Get and set the contents of the status register.
|
|
.It Dv PPIGCTRL , PPISCTRL
|
|
Get and set the contents of the control register.
|
|
The following defines correspond to bits in this register. Setting
|
|
a bit in the control register drives the corresponding output low.
|
|
.Bl -tag -width indent -compact
|
|
.It Dv STROBE
|
|
.It Dv AUTOFEED
|
|
.It Dv nINIT
|
|
.It Dv SELECTIN
|
|
.It Dv PCD
|
|
.El
|
|
.It Dv PPIGEPP , PPISEPP
|
|
Get and set the contents of the EPP control register.
|
|
.It Dv PPIGECR , PPISECR
|
|
Get and set the contents of the ECP control register.
|
|
.It Dv PPIGFIFO , PPISFIFO
|
|
Read and write the ECP FIFO (8-bit operations only).
|
|
.El
|
|
.Sh EXAMPLES
|
|
To present the value 0x5a to the data port, drive STROBE low and then high
|
|
again, the following code fragment can be used:
|
|
.Bd -literal -compact
|
|
|
|
int fd;
|
|
u_int8_t val;
|
|
|
|
val = 0x5a;
|
|
ioctl(fd, PPISDATA, &val);
|
|
ioctl(fd, PPIGCTRL, &val);
|
|
val |= STROBE;
|
|
ioctl(fd, PPISCTRL, &val);
|
|
val &= ~STROBE;
|
|
ioctl(fd, PPISCTRL, &val);
|
|
|
|
.Ed
|
|
.Sh BUGS
|
|
The inverse sense of signals is confusing.
|
|
.Pp
|
|
The
|
|
.Fn ioctl
|
|
interface is slow, and there is no way (yet) to chain multiple operations together.
|
|
.Pp
|
|
The headers required for user applications are not installed as part of the
|
|
standard system.
|