[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, 9 insertions, 2 deletions

diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index 3450108..113e8a2 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -92,7 +92,9 @@ extern void check_efer(void);
 extern int unhandled_signal(struct task_struct *tsk, int sig);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void swiotlb_init(void);
+
+extern void gart_parse_options(char *);
+extern void __init no_iommu_init(void);
 
 extern unsigned long table_start, table_end;
 
@@ -106,12 +108,17 @@ extern int skip_ioapic_setup;
 extern int acpi_ht;
 extern int acpi_disabled;
 
+#ifdef CONFIG_GART_IOMMU
 extern int fallback_aper_order;
 extern int fallback_aper_force;
 extern int iommu_aperture;
-extern int iommu_aperture_disabled;
 extern int iommu_aperture_allowed;
+extern int iommu_aperture_disabled;
 extern int fix_aperture;
+#else
+#define iommu_aperture 0
+#define iommu_aperture_allowed 0
+#endif
 extern int force_iommu;
 
 extern int reboot_force;