[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, 3 insertions, 7 deletions

diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 6810690d604..e7a4d2cd396 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -45,6 +45,7 @@
 #include <linux/kexec.h>
 #include <linux/cpufreq.h>
 #include <linux/dmi.h>
+#include <linux/dma-mapping.h>
 
 #include <asm/mtrr.h>
 #include <asm/uaccess.h>
@@ -63,7 +64,9 @@
 #include <asm/setup.h>
 #include <asm/mach_apic.h>
 #include <asm/numa.h>
+#include <asm/swiotlb.h>
 #include <asm/sections.h>
+#include <asm/gart-mapping.h>
 
 /*
  * Machine setup..
@@ -88,11 +91,6 @@ int bootloader_type;
 
 unsigned long saved_video_mode;
 
-#ifdef CONFIG_SWIOTLB
-int swiotlb;
-EXPORT_SYMBOL(swiotlb);
-#endif
-
 /*
  * Setup options
  */
@@ -389,11 +387,9 @@ static __init void parse_cmdline_early (char ** cmdline_p)
 			numa_setup(from+5); 
 #endif
 
-#ifdef CONFIG_GART_IOMMU 
 		if (!memcmp(from,"iommu=",6)) { 
 			iommu_setup(from+6); 
 		}
-#endif
 
 		if (!memcmp(from,"oops=panic", 10))
 			panic_on_oops = 1;