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RE: cannot open parallel port on 100LX board


It is theoretically possible to access the hardware from 
user space (but inb, outb can't be used because they are
defined empty). In most cases I think you should write
a device driver to do the job. You can find more
information in the following mail thread from a previous
discussion on dev-etrax:



-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com]On">mailto:owner-dev-etrax@xxxxxxx.com]On
Behalf Of Henry Minsky
Sent: Wednesday, June 13, 2001 1:24 AM
To: dev-etrax
Cc: jonashg@xxxxxxx.com
Subject: RE: cannot open parallel port on 100LX board

At 04:18 PM 6/11/01 +0200, you wrote:
>Take a look at the document 
>It describes how to make a device driver that uses the paralell port in 
>manual mode.

I followed the instructions in that document, and compiled a driver that 
operates the
parallel port in manual mode. Very educational!

But I am wondering, is there any easier way to do this? In Linux on the 
386, there
is the ioperm() and inb() out outb() instructions to directly map and  frob 
some memory registers
in the hardware. Is there anything corresponding to this in the ETRAX 2.4 linux
port? I realize that the 386 has some sort of IO address space and 
separate from the regular memory read/write mechanism. It just seems like I 
to be able to get at the etrax hardware without having to write a kernel 
device driver... or does
that defeat all the purpose of the nice MMU and operating system?