xref: /freebsd/share/man/man4/lpt.4 (revision 6990ffd8a95caaba6858ad44ff1b3157d1efba8f)
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2.\" Copyright (c) 1993 Christopher G. Demetriou
3.\" Copyright (c) 1994 Geoffrey M. Rehmet
4.\" Copyright (c) 1999 Nicolas Souchu
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28.\" $FreeBSD$
29.\"
30.Dd February 14, 1999
31.Dt LPT 4
32.Os
33.Sh NAME
34.Nm lpt
35.Nd generic printer device driver
36.Sh SYNOPSIS
37.Cd "device ppbus"
38.Cd "device lpt"
39.Pp
40.Cd "device	ppc0	at isa? port IO_LPT1 irq 7"
41.Cd "device	ppc1	at isa? port IO_LPT2 irq 7"
42.Cd "device	ppc2	at isa? port IO_LPT3 irq 7"
43.Pp
44For BIOS-probed ports:
45.Cd "device ppc0 at isa? port? irq 7"
46.Pp
47For polled ports:
48.Cd "device ppc0 at isa? port?"
49.Cd "device ppc1 at isa? port IO_LPT2"
50.Pp
51For DMA capable parallel port:
52.Cd "device ppc0 at isa? port? irq 7 drq 1"
53.Sh DESCRIPTION
54The current
55.Em lpt
56driver is the port of the original lpt driver to the
57.Xr ppbus 4
58system.
59.Pp
60One purpose of this port was to allow parallel port sharing with other
61parallel devices.
62Secondly, inb()/outb() calls have been replaced by ppbus
63function calls.
64lpt is now arch-independent thanks to the ppbus interface.
65See
66.Xr ppbus 4
67for more info about the ppbus system.
68.Pp
69The parallel port bus is allocated by lpt when the printer device is opened
70and released only when the transfer is completed: either when the device
71is closed or when the entire buffer is sent in interrupt driven mode.
72.Pp
73The driver can be configured to be either interrupt-driven, or
74to poll the printer.  Ports that are configured to be
75interrupt-driven can be switched to polled mode by using the
76.Xr lptcontrol 8
77command.
78.Pp
79Depending on your hardware, extended capabilities may be configured with the
80.Xr lptcontrol 8
81command.
82With an ECP/ISA port, you can take advantage
83of FIFO and DMA.
84.Pp
85In order to retrieve printer info from /dev/lpt0, just apply the
86.Nm cat
87command to the device.
88If the printer supports IEEE1284 nibble mode and has
89data to send to the host, you'll get it.
90.Sh SEE ALSO
91.Xr ppbus 4 ,
92.Xr lptcontrol 8
93.Sh HISTORY
94This driver replaces the functionality of the lpa
95driver, which is now defunct.
96.Sh FILES
97.Bl -tag -width Pa -compact
98.It Pa /dev/lpt0
99first parallel port driver
100.El
101.Sh BUGS
102There are lots of them, especially in cheap parallel port implementations.
103.Pp
104It is only possible to open a lpt port when a printer is connected and
105on-line, making it impossible to run
106.Xr lptcontrol 8
107when there is no printer connected.
108.Pp
109This driver could still stand a rewrite.
110