This used to be a internal function, but virtio
uses multiple structures with the same cap type
to indicate the location of various register
blocks in the pci bars so export it.
let pci.c deal with the special cardbus controller bar0 and
expansion roms.
handle apic interrupt routing for devices behind a cardbus slot.
do not free the pcidev on card removal, as the drivers
most certanly are not prepared to handle this yet.
instead, we provide a pcidevfree() function that just unlinks
the device from pcilist and the parent bridge.
The new pci code is moved to port/pci.[hc] and shared by
all ports.
Each port has its own PCI controller implementation,
providing the pcicfgrw*() functions for low level pci
config space access. The locking for pcicfgrw*() is now
done by the caller (only port/pci.c).
Device drivers now need to include "../port/pci.h" in
addition to "io.h".
The new code now checks bridge windows and membars,
while enumerating the bus, giving the pc driver a chance
to re-assign them. This is needed because some UEFI
implementations fail to assign the bars for some devices,
so we need to do it outselfs. (See pcireservemem()).
While working on this, it was discovered that the pci
code assimed the smallest I/O bar size is 16 (pcibarsize()),
which is wrong. I/O bars can be as small as 4 bytes.
Bit 1 in an I/O bar is also reserved and should be masked off,
making the port mask: port = bar & ~3;
