'\" t
.\"     Title: ieee1284_get_irq_fd
.\"    Author: Tim Waugh <twaugh@redhat.com>
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 04/07/2024
.\"    Manual: Functions
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "IEEE1284_GET_IRQ_FD" "3" "04/07/2024" "[FIXME: source]" "Functions"
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.SH "NAME"
ieee1284_get_irq_fd, ieee1284_clear_irq \- interrupt notification
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ieee1284\&.h>
.fi
.ft
.HP \w'int\ ieee1284_get_irq_fd('u
.BI "int ieee1284_get_irq_fd(struct\ parport\ *" "port" ");"
.HP \w'int\ ieee1284_clear_irq('u
.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\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br
Copyright \(co 2001-2003 Tim Waugh
.br