Accessing 8541 registers from user space

[Kumar Gala]

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