'\" t
.\"     Title: ieee1284_negotiation
.\"    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_NEGOTIATION" "3" "04/07/2024" "[FIXME: source]" "Functions"
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.nh
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.SH "NAME"
ieee1284_negotiate, ieee1284_terminate \- IEEE 1284 negotiation
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <ieee1284\&.h>
.fi
.ft
.HP \w'int\ ieee1284_negotiate('u
.BI "int ieee1284_negotiate(struct\ parport\ *" "port" ", int\ " "mode" ");"
.HP \w'void\ ieee1284_terminate('u
.BI "void ieee1284_terminate(struct\ parport\ *" "port" ");"
.SH "DESCRIPTION"
.PP
These functions are for negotiating to and terminating from IEEE 1284 data transfer modes\&. The default mode is called compatibility mode, or in other words normal printer protocol\&. It is a host\-to\-peripheral mode only\&. There are special modes that allow peripheral\-to\-host transfer as well, which may be negotiated to using
\fBieee1284_negotiate\fR\&. IEEE 1284 negotiation is a process by which the host requests a transfer mode and the peripheral accepts or rejects it\&. An IEEE 1284\-compliant device will require a successful negotiation to a particular mode before it is used for data transfer (but simpler devices may not if they only speak one transfer mode)\&.
.PP
To terminate the special mode and go back to compatilibity mode use
\fBieee1284_terminate\fR\&.
.PP
These functions act on the parallel port associated with
\fIport\fR, which must be claimed\&.
.PP
With a device strictly complying to IEEE 1284 you will need to call
\fBieee1284_terminate\fR
in between any two calls to
\fBieee1284_negotiate\fR
for modes other than
\fBM1284_COMPAT\fR\&.
.SH "AVAILABLE MODES"
.SS "Uni\-directional modes"
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_COMPAT\fR: Compatibility mode\&. Normal printer protocol\&. This is not a negotiated mode, but is the default mode in absence of negotiation\&.
\fBieee1284_negotiate(port, M1284_COMPAT)\fR
is equivalent to
\fBieee1284_terminate(port)\fR\&. This host\-to\-peripheral mode is used for sending data to printers, and is historically the mode that has been used for that before IEEE 1284\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_NIBBLE\fR: Nibble mode\&. This peripheral\-to\-host mode uses the status lines to read data from the peripheral four bits at a time\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_BYTE\fR: Byte mode\&. This peripheral\-to\-host mode uses the data lines in reverse mode to read data from the peripheral a byte at a time\&.
.RE
.SS "Bi\-directional modes"
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_ECP\fR: ECP mode\&. On entry to ECP mode it is a host\-to\-peripheral (i\&.e\&. forward) mode, but it may be set to reverse mode using
\fBieee1284_ecp_fwd_to_rev\fR(3)\&. It is common for PC hardware to provide assistance with this mode by the use of a FIFO which the host (or, in reverse mode, the peripheral) may fill, so that the hardware can do the handshaking itself\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_EPP\fR: EPP mode\&. In this bi\-directional mode the direction of data transfer is signalled at each byte\&.
.RE
.SS "Mode variations"
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_FLAG_DEVICEID\fR: Device ID retrieval\&. This flag may be combined with a nibble, byte, or ECP mode to notify the device that it should send its IEEE 1284 Device ID when asked for data\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_BECP\fR: Bounded ECP is a modification to ECP that makes it more robust at the point that the direction is changed\&. (Unfortunately it is not yet implemented in the Linux kernel driver\&.)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
\fBM1284_ECPRLE\fR: ECP with run length encoding\&. In this mode, consecutive data bytes of the same value may be transferred in only a few cycles\&.
.RE
.SH "RETURN VALUE"
.PP
\fBE1284_OK\fR
.RS 4
The negotiation was successful\&.
.RE
.PP
\fBE1284_NOTAVAIL\fR
.RS 4
Negotiation is not available with this port type\&.
.RE
.PP
\fBE1284_REJECTED\fR
.RS 4
Negotiation was rejected by the peripheral\&.
.RE
.PP
\fBE1284_NEGFAILED\fR
.RS 4
Negotiation failed for some reason\&. Perhaps the device is not IEEE 1284 compliant\&.
.RE
.PP
\fBE1284_SYS\fR
.RS 4
A system error occured during negotiation\&.
.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