For the 575 (CardBus), the PCI BAR2 register contains the address for
the cardbus specific registers.  Treat this address as an array of 3 ulongs
and acknowledge each interrupt as follows:

/* On the 575B and C, interrupts need to be acknowledged in CardBus memory space */
static void
intrack3c575(ulong *cbfns)
{
	cbfns[1] = 0x8000;
}

peter.