287 lines
9.3 KiB
ReStructuredText
287 lines
9.3 KiB
ReStructuredText
|
Parport
|
||
|
|
+++++++
|
||
|
|
|
||
|
|
The ``parport`` code provides parallel-port support under Linux. This
|
||
|
|
includes the ability to share one port between multiple device
|
||
|
|
drivers.
|
||
|
|
|
||
|
|
You can pass parameters to the ``parport`` code to override its automatic
|
||
|
|
detection of your hardware. This is particularly useful if you want
|
||
|
|
to use IRQs, since in general these can't be autoprobed successfully.
|
||
|
|
By default IRQs are not used even if they **can** be probed. This is
|
||
|
|
because there are a lot of people using the same IRQ for their
|
||
|
|
parallel port and a sound card or network card.
|
||
|
|
|
||
|
|
The ``parport`` code is split into two parts: generic (which deals with
|
||
|
|
port-sharing) and architecture-dependent (which deals with actually
|
||
|
|
using the port).
|
||
|
|
|
||
|
|
|
||
|
|
Parport as modules
|
||
|
|
==================
|
||
|
|
|
||
|
|
If you load the `parport`` code as a module, say::
|
||
|
|
|
||
|
|
# insmod parport
|
||
|
|
|
||
|
|
to load the generic ``parport`` code. You then must load the
|
||
|
|
architecture-dependent code with (for example)::
|
||
|
|
|
||
|
|
# insmod parport_pc io=0x3bc,0x378,0x278 irq=none,7,auto
|
||
|
|
|
||
|
|
to tell the ``parport`` code that you want three PC-style ports, one at
|
||
|
|
0x3bc with no IRQ, one at 0x378 using IRQ 7, and one at 0x278 with an
|
||
|
|
auto-detected IRQ. Currently, PC-style (``parport_pc``), Sun ``bpp``,
|
||
|
|
Amiga, Atari, and MFC3 hardware is supported.
|
||
|
|
|
||
|
|
PCI parallel I/O card support comes from ``parport_pc``. Base I/O
|
||
|
|
addresses should not be specified for supported PCI cards since they
|
||
|
|
are automatically detected.
|
||
|
|
|
||
|
|
|
||
|
|
modprobe
|
||
|
|
--------
|
||
|
|
|
||
|
|
If you use modprobe , you will find it useful to add lines as below to a
|
||
|
|
configuration file in /etc/modprobe.d/ directory::
|
||
|
|
|
||
|
|
alias parport_lowlevel parport_pc
|
||
|
|
options parport_pc io=0x378,0x278 irq=7,auto
|
||
|
|
|
||
|
|
modprobe will load ``parport_pc`` (with the options ``io=0x378,0x278 irq=7,auto``)
|
||
|
|
whenever a parallel port device driver (such as ``lp``) is loaded.
|
||
|
|
|
||
|
|
Note that these are example lines only! You shouldn't in general need
|
||
|
|
to specify any options to ``parport_pc`` in order to be able to use a
|
||
|
|
parallel port.
|
||
|
|
|
||
|
|
|
||
|
|
Parport probe [optional]
|
||
|
|
------------------------
|
||
|
|
|
||
|
|
In 2.2 kernels there was a module called ``parport_probe``, which was used
|
||
|
|
for collecting IEEE 1284 device ID information. This has now been
|
||
|
|
enhanced and now lives with the IEEE 1284 support. When a parallel
|
||
|
|
port is detected, the devices that are connected to it are analysed,
|
||
|
|
and information is logged like this::
|
||
|
|
|
||
|
|
parport0: Printer, BJC-210 (Canon)
|
||
|
|
|
||
|
|
The probe information is available from files in ``/proc/sys/dev/parport/``.
|
||
|
|
|
||
|
|
|
||
|
|
Parport linked into the kernel statically
|
||
|
|
=========================================
|
||
|
|
|
||
|
|
If you compile the ``parport`` code into the kernel, then you can use
|
||
|
|
kernel boot parameters to get the same effect. Add something like the
|
||
|
|
following to your LILO command line::
|
||
|
|
|
||
|
|
parport=0x3bc parport=0x378,7 parport=0x278,auto,nofifo
|
||
|
|
|
||
|
|
You can have many ``parport=...`` statements, one for each port you want
|
||
|
|
to add. Adding ``parport=0`` to the kernel command-line will disable
|
||
|
|
parport support entirely. Adding ``parport=auto`` to the kernel
|
||
|
|
command-line will make ``parport`` use any IRQ lines or DMA channels that
|
||
|
|
it auto-detects.
|
||
|
|
|
||
|
|
|
||
|
|
Files in /proc
|
||
|
|
==============
|
||
|
|
|
||
|
|
If you have configured the ``/proc`` filesystem into your kernel, you will
|
||
|
|
see a new directory entry: ``/proc/sys/dev/parport``. In there will be a
|
||
|
|
directory entry for each parallel port for which parport is
|
||
|
|
configured. In each of those directories are a collection of files
|
||
|
|
describing that parallel port.
|
||
|
|
|
||
|
|
The ``/proc/sys/dev/parport`` directory tree looks like::
|
||
|
|
|
||
|
|
parport
|
||
|
|
|-- default
|
||
|
|
| |-- spintime
|
||
|
|
| `-- timeslice
|
||
|
|
|-- parport0
|
||
|
|
| |-- autoprobe
|
||
|
|
| |-- autoprobe0
|
||
|
|
| |-- autoprobe1
|
||
|
|
| |-- autoprobe2
|
||
|
|
| |-- autoprobe3
|
||
|
|
| |-- devices
|
||
|
|
| | |-- active
|
||
|
|
| | `-- lp
|
||
|
|
| | `-- timeslice
|
||
|
|
| |-- base-addr
|
||
|
|
| |-- irq
|
||
|
|
| |-- dma
|
||
|
|
| |-- modes
|
||
|
|
| `-- spintime
|
||
|
|
`-- parport1
|
||
|
|
|-- autoprobe
|
||
|
|
|-- autoprobe0
|
||
|
|
|-- autoprobe1
|
||
|
|
|-- autoprobe2
|
||
|
|
|-- autoprobe3
|
||
|
|
|-- devices
|
||
|
|
| |-- active
|
||
|
|
| `-- ppa
|
||
|
|
| `-- timeslice
|
||
|
|
|-- base-addr
|
||
|
|
|-- irq
|
||
|
|
|-- dma
|
||
|
|
|-- modes
|
||
|
|
`-- spintime
|
||
|
|
|
||
|
|
.. tabularcolumns:: |p{4.0cm}|p{13.5cm}|
|
||
|
|
|
||
|
|
======================= =======================================================
|
||
|
|
File Contents
|
||
|
|
======================= =======================================================
|
||
|
|
``devices/active`` A list of the device drivers using that port. A "+"
|
||
|
|
will appear by the name of the device currently using
|
||
|
|
the port (it might not appear against any). The
|
||
|
|
string "none" means that there are no device drivers
|
||
|
|
using that port.
|
||
|
|
|
||
|
|
``base-addr`` Parallel port's base address, or addresses if the port
|
||
|
|
has more than one in which case they are separated
|
||
|
|
with tabs. These values might not have any sensible
|
||
|
|
meaning for some ports.
|
||
|
|
|
||
|
|
``irq`` Parallel port's IRQ, or -1 if none is being used.
|
||
|
|
|
||
|
|
``dma`` Parallel port's DMA channel, or -1 if none is being
|
||
|
|
used.
|
||
|
|
|
||
|
|
``modes`` Parallel port's hardware modes, comma-separated,
|
||
|
|
meaning:
|
||
|
|
|
||
|
|
- PCSPP
|
||
|
|
PC-style SPP registers are available.
|
||
|
|
|
||
|
|
- TRISTATE
|
||
|
|
Port is bidirectional.
|
||
|
|
|
||
|
|
- COMPAT
|
||
|
|
Hardware acceleration for printers is
|
||
|
|
available and will be used.
|
||
|
|
|
||
|
|
- EPP
|
||
|
|
Hardware acceleration for EPP protocol
|
||
|
|
is available and will be used.
|
||
|
|
|
||
|
|
- ECP
|
||
|
|
Hardware acceleration for ECP protocol
|
||
|
|
is available and will be used.
|
||
|
|
|
||
|
|
- DMA
|
||
|
|
DMA is available and will be used.
|
||
|
|
|
||
|
|
Note that the current implementation will only take
|
||
|
|
advantage of COMPAT and ECP modes if it has an IRQ
|
||
|
|
line to use.
|
||
|
|
|
||
|
|
``autoprobe`` Any IEEE-1284 device ID information that has been
|
||
|
|
acquired from the (non-IEEE 1284.3) device.
|
||
|
|
|
||
|
|
``autoprobe[0-3]`` IEEE 1284 device ID information retrieved from
|
||
|
|
daisy-chain devices that conform to IEEE 1284.3.
|
||
|
|
|
||
|
|
``spintime`` The number of microseconds to busy-loop while waiting
|
||
|
|
for the peripheral to respond. You might find that
|
||
|
|
adjusting this improves performance, depending on your
|
||
|
|
peripherals. This is a port-wide setting, i.e. it
|
||
|
|
applies to all devices on a particular port.
|
||
|
|
|
||
|
|
``timeslice`` The number of milliseconds that a device driver is
|
||
|
|
allowed to keep a port claimed for. This is advisory,
|
||
|
|
and driver can ignore it if it must.
|
||
|
|
|
||
|
|
``default/*`` The defaults for spintime and timeslice. When a new
|
||
|
|
port is registered, it picks up the default spintime.
|
||
|
|
When a new device is registered, it picks up the
|
||
|
|
default timeslice.
|
||
|
|
======================= =======================================================
|
||
|
|
|
||
|
|
Device drivers
|
||
|
|
==============
|
||
|
|
|
||
|
|
Once the parport code is initialised, you can attach device drivers to
|
||
|
|
specific ports. Normally this happens automatically; if the lp driver
|
||
|
|
is loaded it will create one lp device for each port found. You can
|
||
|
|
override this, though, by using parameters either when you load the lp
|
||
|
|
driver::
|
||
|
|
|
||
|
|
# insmod lp parport=0,2
|
||
|
|
|
||
|
|
or on the LILO command line::
|
||
|
|
|
||
|
|
lp=parport0 lp=parport2
|
||
|
|
|
||
|
|
Both the above examples would inform lp that you want ``/dev/lp0`` to be
|
||
|
|
the first parallel port, and /dev/lp1 to be the **third** parallel port,
|
||
|
|
with no lp device associated with the second port (parport1). Note
|
||
|
|
that this is different to the way older kernels worked; there used to
|
||
|
|
be a static association between the I/O port address and the device
|
||
|
|
name, so ``/dev/lp0`` was always the port at 0x3bc. This is no longer the
|
||
|
|
case - if you only have one port, it will default to being ``/dev/lp0``,
|
||
|
|
regardless of base address.
|
||
|
|
|
||
|
|
Also:
|
||
|
|
|
||
|
|
* If you selected the IEEE 1284 support at compile time, you can say
|
||
|
|
``lp=auto`` on the kernel command line, and lp will create devices
|
||
|
|
only for those ports that seem to have printers attached.
|
||
|
|
|
||
|
|
* If you give PLIP the ``timid`` parameter, either with ``plip=timid`` on
|
||
|
|
the command line, or with ``insmod plip timid=1`` when using modules,
|
||
|
|
it will avoid any ports that seem to be in use by other devices.
|
||
|
|
|
||
|
|
* IRQ autoprobing works only for a few port types at the moment.
|
||
|
|
|
||
|
|
Reporting printer problems with parport
|
||
|
|
=======================================
|
||
|
|
|
||
|
|
If you are having problems printing, please go through these steps to
|
||
|
|
try to narrow down where the problem area is.
|
||
|
|
|
||
|
|
When reporting problems with parport, really you need to give all of
|
||
|
|
the messages that ``parport_pc`` spits out when it initialises. There are
|
||
|
|
several code paths:
|
||
|
|
|
||
|
|
- polling
|
||
|
|
- interrupt-driven, protocol in software
|
||
|
|
- interrupt-driven, protocol in hardware using PIO
|
||
|
|
- interrupt-driven, protocol in hardware using DMA
|
||
|
|
|
||
|
|
The kernel messages that ``parport_pc`` logs give an indication of which
|
||
|
|
code path is being used. (They could be a lot better actually..)
|
||
|
|
|
||
|
|
For normal printer protocol, having IEEE 1284 modes enabled or not
|
||
|
|
should not make a difference.
|
||
|
|
|
||
|
|
To turn off the 'protocol in hardware' code paths, disable
|
||
|
|
``CONFIG_PARPORT_PC_FIFO``. Note that when they are enabled they are not
|
||
|
|
necessarily **used**; it depends on whether the hardware is available,
|
||
|
|
enabled by the BIOS, and detected by the driver.
|
||
|
|
|
||
|
|
So, to start with, disable ``CONFIG_PARPORT_PC_FIFO``, and load ``parport_pc``
|
||
|
|
with ``irq=none``. See if printing works then. It really should,
|
||
|
|
because this is the simplest code path.
|
||
|
|
|
||
|
|
If that works fine, try with ``io=0x378 irq=7`` (adjust for your
|
||
|
|
hardware), to make it use interrupt-driven in-software protocol.
|
||
|
|
|
||
|
|
If **that** works fine, then one of the hardware modes isn't working
|
||
|
|
right. Enable ``CONFIG_FIFO`` (no, it isn't a module option,
|
||
|
|
and yes, it should be), set the port to ECP mode in the BIOS and note
|
||
|
|
the DMA channel, and try with::
|
||
|
|
|
||
|
|
io=0x378 irq=7 dma=none (for PIO)
|
||
|
|
io=0x378 irq=7 dma=3 (for DMA)
|
||
|
|
|
||
|
|
----------
|
||
|
|
|
||
|
|
philb@gnu.org
|
||
|
|
tim@cyberelk.net
|