LP(4) Linux Programmer's Manual LP(4)
NAME
lp - line printer devices
SYNOPSIS
#include <linux/lp.h>
CONFIGURATION
lp[0-2] are character devices for the parallel line printers; they have
major number 6 and minor number 0-2. The minor numbers correspond to
the printer port base addresses 0x03bc, 0x0378, and 0x0278. Usually
they have mode 220 and are owned by user root and group lp. You can
use printer ports either with polling or with interrupts. Interrupts
are recommended when high traffic is expected, for example, for laser
printers. For typical dot matrix printers, polling will usually be
enough. The default is polling.
DESCRIPTION
The following ioctl(2) calls are supported:
int ioctl(int fd, LPTIME, int arg)
Sets the amount of time that the driver sleeps before rechecking
the printer when the printer's buffer appears to be filled to
arg. If you have a fast printer, decrease this number; if you
have a slow printer, then increase it. This is in hundredths of
a second, the default 2 being 0.02 seconds. It influences only
the polling driver.
int ioctl(int fd, LPCHAR, int arg)
Sets the maximum number of busy-wait iterations which the
polling driver does while waiting for the printer to get ready
for receiving a character to arg. If printing is too slow, in-
crease this number; if the system gets too slow, decrease this
number. The default is 1000. It influences only the polling
driver.
int ioctl(int fd, LPABORT, int arg)
If arg is 0, the printer driver will retry on errors, otherwise
it will abort. The default is 0.
int ioctl(int fd, LPABORTOPEN, int arg)
If arg is 0, open(2) will be aborted on error, otherwise error
will be ignored. The default is to ignore it.
int ioctl(int fd, LPCAREFUL, int arg)
If arg is 0, then the out-of-paper, offline, and error signals
are required to be false on all writes, otherwise they are ig-
nored. The default is to ignore them.
int ioctl(int fd, LPWAIT, int arg)
Sets the number of busy waiting iterations to wait before strob-
ing the printer to accept a just-written character, and the num-
ber of iterations to wait before turning the strobe off again,
to arg. The specification says this time should be 0.5 mi-
croseconds, but experience has shown the delay caused by the
code is already enough. For that reason, the default value is
0. This is used for both the polling and the interrupt driver.
int ioctl(int fd, LPSETIRQ, int arg)
This ioctl(2) requires superuser privileges. It takes an int
containing the new IRQ as argument. As a side effect, the
printer will be reset. When arg is 0, the polling driver will
be used, which is also default.
int ioctl(int fd, LPGETIRQ, int *arg)
Stores the currently used IRQ in arg.
int ioctl(int fd, LPGETSTATUS, int *arg)
Stores the value of the status port in arg. The bits have the
following meaning:
LP_PBUSY inverted busy input, active high
LP_PACK unchanged acknowledge input, active low
LP_POUTPA unchanged out-of-paper input, active high
LP_PSELECD unchanged selected input, active high
LP_PERRORP unchanged error input, active low
Refer to your printer manual for the meaning of the signals.
Note that undocumented bits may also be set, depending on your
printer.
int ioctl(int fd, LPRESET)
Resets the printer. No argument is used.
FILES
/dev/lp*
SEE ALSO
chmod(1), chown(1), mknod(1), lpcntl(8), tunelp(8)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 1995-01-15 LP(4)