Messages in this thread | | | From | Kumar Gala <> | Subject | Re: tracking of PCI address space | Date | Wed, 8 Apr 2009 16:53:52 -0500 |
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On Apr 8, 2009, at 4:49 PM, Ira Snyder wrote:
> On Wed, Apr 08, 2009 at 03:53:55PM -0500, Kumar Gala wrote: >> I was wondering if we have anything that tracks regions associated >> with >> the "inbound" side of a pci_bus. >> >> What I mean is on embedded PPC we have window/mapping registers for >> both >> inbound (accessing memory on the SoC) and outbound (access PCI device >> MMIO, IO etc). The combination of the inbound & outbound convey what >> exists in the PCI address space vs CPU physical address space (and >> how to >> map from one to the other). Today in the PPC land we only attach >> outbound windows to the pci_bus. So technically the inbound side >> information (like what subset of physical memory is visible on the >> PCI >> bus) seems to be lost. >> > > To the best of my knowledge there is no API to set inbound windows in > Linux. I've been implementing a virtio-over-PCI driver which needs the > inbound windows. I set them up myself during driver probe, using > get_immrbase() to get the IMMR registers. This board is a PCI Slave / > Agent, it doesn't even have PCI support compiled into the kernel.
I'm not concerned explicitly about setting up inbound windows, its more about have a consistent view of the PCI address space which may be different from the CPU physical address space.
I'm working on code to actually setup the inbound windows on 85xx/86xx class devices (based on dma-ranges property in the device tree). As I was thinking about this I realized that the send of ranges/dma-ranges in the .dts and what we map to outbound vs inbound changes if we an agent or host.
- k
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