Allwinner MBUS and DMA-ops rework

The Allwinner SoCs have a number of high-bandwidth devices connected to
a memory bus with a different RAM mapping than the CPU.

This was addressed before through drivers setting the DMA offsets
directly, and subsequently changed to calls to dma_direct_set_offset.
However that wasn't really meant to be exported to modules (and thus
drivers). The duplicated code also led to small inconsistencies across
drivers in how we dealt with DT backward compatibility.

Move all that DMA setup code into a platform bus notifier to share that
code and remove the export on dma_direct_set_offset.
dma-mapping: remove the dma_direct_set_offset export

Drop the dma_direct_set_offset export and move the declaration to
dma-map-ops.h now that the Allwinner drivers have stopped calling it.

Signed-off-by: Christoph Hellwig <>
Signed-off-by: Maxime Ripard <>
7 files changed