DMA with powerspan II -Fpga card

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I had posted earlier my issues with Fpga card.

The  AMIRIX fpga card uses powerspan II pci bus switch fro Tundra. The
powerpc inside teh fpga has linux running..I have some data in my PLB
master/slave module which has to be transferred to the host pc. So I
was suggested to llok into DMA transfer part. I went through the
powerspan II manual . It doesnt provide the details of data cycle for
the DMA . i.e it only says to write the DMA configuration registers
with the source address , destination address... and then raisethe go
signal. Now my problem is that the source address  needs to be the
on-board RAM address. I dont want to use the onboard RAM.I dont want to
use the powerpc either. I wanted to write a module in vhdl to do the
confguration adn the forward the data to the bridge. I dont know
whether this is possible. I

 I dont have experience in this field. How can I do a transfer of data
from my master/slave module to the host computer?
Is there a way ?

Re: DMA with powerspan II -Fpga card

Because all the addresses on the PCI bus are set by a mixture of card
requirements and software allocation during PCI configuration you will need
software/driver to read the allocation and give the relevant details to your
card for the DMA transfer.

John Adair
Enterpoint Ltd. - Home of Raggedstone1. The Low Cost Spartan-3 PCI
Development Board.

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Re: DMA with powerspan II -Fpga card
I have started with the driver on the host side but the thing is I am
still not cear about some things. I have access to the config registers
from the host side. I also can initiate a data transfer from the host
side and read data from the on-board RAM. I also have an option of
configuring from the Processor bus side( interfaced with fpga). but I
dont know how to give data to the pci bridge. i.e how to initiate a
transfer from inside the fpga without using the on-board RAM or powerpc
in the tranfer.The user manual says only how to configure i.e give the
start address( source address in the ram ) , size of data and the
destination address. It doesnt  tell how to go about if i have to send
data without using the RAM, the timing  diagrams.

Re: DMA with powerspan II -Fpga card
I am working on drivers n the host side. I wasnt clear about few
things.  I can configure the bridge from the fpga side over the
processor bus. In the manual its not stated as to how to do the data
transfer without using the on-board RAM. It only specifies how to
configure the bridge for the DMA transfer (with initiation fromthe fpga
side ) i.e to specify the start address on the on-board ram ,
destination address and the size. How do I go about tranferring the
data without using the on-board external RAM.
Is it possible?

Re: DMA with powerspan II -Fpga card

As I thing Brian said you need to look at the chip specification. Usually
you will find a register/s location at a particular offset/s from the BAR
base address for these kind of DMA transfers but I don't have a lot recent
PLX experience to expand on that.

John Adair
Enterpoint Ltd. - Home of Broaddown2. The Ultimate Spartan3 Development

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