I've pulled this into the dma-mapping for-next branch so that we get
a few days exposure before then end of the merge window. If there is
anything important (e.g. the powerpc naming issue) please send
incremental patches.
Almost every architecture supports a direct dma mapping implementation,
where no iommu is used and the device dma address is a 1:1 mapping to
the physical address or has a simple linear offset. Currently the
code for this implementation is most duplicated over the architectures,
and the
