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[dma] Modify DMA API to simplify calculation of medial addresses

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Redefine the value stored within a DMA mapping to be the offset
between physical addresses and DMA addresses within the mapped region.

Provide a dma() wrapper function to calculate the DMA address for any
pointer within a mapped region, thereby simplifying the use cases when
a device needs to be given addresses other than the region start
address.

On a platform using the "flat" DMA implementation the DMA offset for
any mapped region is always zero, with the result that dma_map() can
be optimised away completely and dma() reduces to a straightforward
call to virt_to_phys().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2020-11-25 15:52:00 +00:00
parent 24ef743778
commit cf12a41703
7 changed files with 100 additions and 58 deletions
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2
src/core/dma.c
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@@ -46,6 +46,7 @@ PROVIDE_DMAAPI_INLINE ( flat, dma_unmap );
PROVIDE_DMAAPI_INLINE ( flat, dma_alloc );
PROVIDE_DMAAPI_INLINE ( flat, dma_free );
PROVIDE_DMAAPI_INLINE ( flat, dma_set_mask );
PROVIDE_DMAAPI_INLINE ( flat, dma_phys );
/******************************************************************************
*
@@ -138,6 +139,7 @@ PROVIDE_DMAAPI ( op, dma_unmap, dma_op_unmap );
PROVIDE_DMAAPI ( op, dma_alloc, dma_op_alloc );
PROVIDE_DMAAPI ( op, dma_free, dma_op_free );
PROVIDE_DMAAPI ( op, dma_set_mask, dma_op_set_mask );
PROVIDE_DMAAPI_INLINE ( op, dma_phys );
/******************************************************************************
*