Re: [ECOS] 8260 driver cannot access DPRAM

[Gary Thomas <gary at mlbassoc dot com>]

On Mon, 2003-09-29 at 14:41, Todd Smith wrote:
> I am writing an HDLC driver using SCC3 on an 8250 (an 8260 variant). 
> Using a build a coworker has done for the rattler card, I've started on 
> a basic driver. My problem is that my code cannot access the DPRAM. 
> Using the address 0x04700000 as the base of this RAM, I get a 
> segmentation violation when I try to access anything there. In fact, gdb 
> can't even access that memory (e.g. when I try to dump at that address). 
> I know this is the same memory the serial and ethernet driver also 
> access so it must be possible. Seems like some memory protection is 
> going on. In an attempt to take some baby steps and get something basic 
> running, I have not added my driver as a package (not sure if this makes 
> a difference) but I have added an init function to the drivers table via 
> the DEVTAB_ENTRY macro. The init function gets a segmentation violation 
> as soon as it tries to access the cpcr register in the DPRAM.
> 

The Rattler DPRAM is not at 0x04700000 :-(

Try using CYGARC_IMM_BASE (0xFF000000) instead.  You also might look at
some of the other drivers for that platform to see how the CPM is
accessed.

-- 
Gary Thomas <gary@mlbassoc.com>
MLB Associates


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