Problem: Need to arbitrary set a PCI bridge memory window (PCI CFG MEM
BASE and MEM LIMIT)
I am writing a linux vme driver for a PCI-VME bridge (Tundra universe2).
The device is located behind a AMD8111 PCI bridge .
When linux comes up, it reprograms all the PCI bridges (previously set
by the firmware). The problem is that it only allocates a memory window
large enough to accomodate the space requirements of subordinate PCI
devices as defined by the BAR registers. My problem is that the Tundra
PCI-VME bridge "consumes" a lot of extra address space (not decoded by
its PCI BARs) for the purpose of accessing the VME bus. Accessing VME is
done by programming several windows on the PCI-VME bridge. Anytime a PCI
address falls in the programmed window is decoded, a VME access is done.
I need around 1GBytes to access VME. So I need to be able forward that
big a range to the PCI bus that holds the PCI-VME bridge. But the
problem is that the AMD8111 doesn't let me do it since it only allows me
to acces the registers of the PCI-VME bridge, as defined by the BARs.
Any idea, how I could force the AMD8111 PCI bridge to pass the 1GBytes
range to the PCI-VME controller?
Thanks
-jf simon.
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