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From: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: Accessing 8541 registers from user space
Date: Wed, 16 May 2007 19:36:43 -0500
To: Charles Krinke <ckrinke@istor.com>
Cc: Randy Brown <rbrown@istor.com>, Vahid Fereydounkolahi <vahidf@istor.com>,
	Chris Carlson <ccarlson@istor.com>,
	Kevin Smith <ksmith@istor.com>, linuxppc-embedded@ozlabs.org
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On May 16, 2007, at 4:59 PM, Charles Krinke wrote:

> I have a need to be able to read and write the gpio data registers  
> PDATC
> and PDATD from a user space program.
>
> We have a userspace program that succesfully mmaps an offset in / 
> dev/mem
> and reads/writes registers in a CPLD at 0xFF00_0000.
>
> The issue seems to be that when I mmap /dev/mem to 0xE000_0D50 to read
> the PDATC register, Linux-2.6.17.11 just locks up.
>
> Can anyone shed a little light on why this could be happening?

One theory is you aren't reading PDATC at the right offset.  Not sure  
what happens if you read a non-existent register offset.

I'm think you want 0xe009_0d50.

- k