[PATCH] x86_64: Use function pointers to call DMA mapping functions

AK: I hacked Muli's original patch a lot and there were a lot
of changes - all bugs are probably to blame on me now.
There were also some changes in the fall back behaviour
for swiotlb - in particular it doesn't try to use GFP_DMA
now anymore. Also all DMA mapping operations use the
same core dma_alloc_coherent code with proper fallbacks now.
And various other changes and cleanups.

Known problems: iommu=force swiotlb=force together breaks
                needs more testing.

This patch cleans up x86_64's DMA mapping dispatching code. Right now
we have three possible IOMMU types: AGP GART, swiotlb and nommu, and
in the future we will also have Xen's x86_64 swiotlb and other HW
IOMMUs for x86_64. In order to support all of them cleanly, this
patch:

- introduces a struct dma_mapping_ops with function pointers for each
  of the DMA mapping operations of gart (AMD HW IOMMU), swiotlb
  (software IOMMU) and nommu (no IOMMU).

- gets rid of:

  if (swiotlb)
      return swiotlb_xxx();

- PCI_DMA_BUS_IS_PHYS is now checked against the dma_ops being set
This makes swiotlb faster by avoiding double copying in some cases.

Signed-Off-By: Muli Ben-Yehuda <mulix@mulix.org>
Signed-Off-By: Jon D. Mason <jdmason@us.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/asm-x86_64/gart-mapping.h b/include/asm-x86_64/gart-mapping.h
new file mode 100644
index 00000000000..ada497b0b55
--- /dev/null
+++ b/include/asm-x86_64/gart-mapping.h
@@ -0,0 +1,16 @@
+#ifndef _X8664_GART_MAPPING_H
+#define _X8664_GART_MAPPING_H 1
+
+#include <linux/types.h>
+#include <asm/types.h>
+
+struct device;
+
+extern void*
+gart_alloc_coherent(struct device *dev, size_t size,
+        dma_addr_t *dma_handle, gfp_t gfp);
+
+extern int
+gart_dma_supported(struct device *hwdev, u64 mask);
+
+#endif /* _X8664_GART_MAPPING_H */