You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
267 lines
8.8 KiB
267 lines
8.8 KiB
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 |
|
|
|
|
|
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: |
|
|
|
o polling |
|
o interrupt-driven, protocol in software |
|
o interrupt-driven, protocol in hardware using PIO |
|
o 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_PARPORT_PC_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
|
|
|