.\"     Title: ieee1284_get_irq_fd
.\"    Author: Tim Waugh <twaugh@redhat.com>
.\" Generator: DocBook XSL Stylesheets v1.72.0 <http://docbook.sf.net/>
.\"      Date: 09/18/2007
.\"    Manual: Functions
.\"    Source: 
.\"
.TH "IEEE1284_GET_IRQ_FD" "3" "09/18/2007" "" "Functions"
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
ieee1284_get_irq_fd, ieee1284_clear_irq \- interrupt notification
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ieee1284.h>
.fi
.ft
.HP 24
.BI "int ieee1284_get_irq_fd(struct\ parport\ *" "port" ");"
.HP 23
.BI "int ieee1284_clear_irq(struct\ parport\ *" "port" ",\ unsigned\ int\ *" "count" ");"
.SH "DESCRIPTION"
.PP
If the
\fIport\fR
has a configured interrupt line and the port type supports interrupt notification, it is possible to obtain a file descriptor that may be used for
\fBselect\fR(2)
or
\fBpoll\fR(2). Any event (readable, writable or exception) means that an interrupt has been triggered. No operations other than
\fBselect\fR
or
\fBpoll\fR
may be performed on the file descriptor.
.PP
The port must be open in order to call
\fBieee1284_get_irq_fd\fR, and must be claimed when using
\fBselect\fR
or
\fBpoll\fR.
.PP
The caller must not close the file descriptor, and may not use it at all when the port is not claimed.
.PP
When an interrupt has been detected, the caller must call
\fBieee1284_clear_irq\fR
to clear the interrupt condition, at which point the number of interrupts raised can be obtained by supplying a non\-\fBNULL\fR
\fIcount\fR.
.SH "RETURN VALUE"
.PP
For
\fBieee1284_get_irq_fd\fR: If the return value is negative then it is an error code listed below. Otherwise it is a valid file descriptor.
.PP
\fBE1284_NOTAVAIL\fR
.RS 4
No such file descriptor is available.
.RE
.PP
\fBE1284_INVALIDPORT\fR
.RS 4
The
\fIport\fR
parameter is invalid (for instance, perhaps the
\fIport\fR
is not open).
.RE
.PP
For
\fBieee1284_clear_irq\fR:
.PP
\fBE1284_OK\fR
.RS 4
The interrupt has been cleared. If
\fIcount\fR
was not
\fBNULL\fR
the count of interrupts has been atomically stored to
\fIcount\fR
and reset.
.RE
.PP
\fBE1284_NOTAVAIL\fR
.RS 4
The
\fIcount\fR
parameter was not
\fBNULL\fR
but interrupt counting is not supported on this type of port. The interrupt has been cleared.
.RE
.PP
\fBE1284_SYS\fR
.RS 4
There was a problem clearing the interrupt.
.RE
.PP
\fBE1284_INVALIDPORT\fR
.RS 4
The
\fIport\fR
parameter is invalid (for instance, perhaps the
\fIport\fR
is not claimed).
.RE
.SH "AUTHOR"
.PP
\fBTim Waugh\fR <\&twaugh@redhat.com\&>
.sp -1n
.IP "" 4
Author.
.SH "COPYRIGHT"
Copyright \(co 2001\-2003 Tim Waugh
.br