Re: PowerPC Local Bus

[David Hawkins <dwh@ovro.caltech.edu>]

Fredrik Roubert wrote:
> Hi!
> 
> I'm about to write drivers for some FPGA's that are connected to the
> local bus of a PowerQUICC II Pro processor and use the user-programmable
> machines (UPM's) to transfer data over the bus. What code does already
> exist for Linux to help me with this? In the stock kernels, I can't even
> find a structure definition for the registers of the local bus
> controller, but it seems strange that no-one has written such code
> before me. Will I really have to write everything from scratch, or what
> code is there that I don't know about yet?
> 
> Cheers // Fredrik Roubert
> 

Hi Fredrik,

I'm going to working on something similar soon. If you want
to discuss it off-list, feel free to. We can report the
results back to the list once we have something working.

This is something that can either go in U-Boot or Linux. The
UPM looks fairly easy to setup. Freescale has a UPM programming
tool that allows you to setup waveforms for the single-read/write
and burst-read/write sequences. I was going to connect up
an FPGA to the MPC8349E-MDS local bus (using the unloaded
SDRAM pads) and then capture logic analyzer traces of the
transactions.

I plan to setup a burst mode interface to an FPGA. Actually,
I'll probably decode one chip select to non-burst registers,
and another to burstable memory.

Like I said, we can chat off-list if you like since this discussion
will not be of general interest (but if anyone thinks this should
stay on-list, let me know, and we'll discuss it here).

What FPGA family are you using? I'll be attaching an Altera
Stratix II FPGA onto the local-bus.

Dave Hawkins
Caltech.