powerpc: Add support for swiotlb on 32-bit

This patch includes the basic infrastructure to use swiotlb
bounce buffering on 32-bit powerpc.  It is not yet enabled on
any platforms.  Probably the most interesting bit is the
addition of addr_needs_map to dma_ops - we need this as
a dma_op because the decision of whether or not an addr
can be mapped by a device is device-specific.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ff755398ce28..93a61898b259 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -300,9 +300,19 @@ config IOMMU_VMERGE
 config IOMMU_HELPER
         def_bool PPC64
 
+config SWIOTLB
+        bool "SWIOTLB support"
+        default n
+        select IOMMU_HELPER
+        ---help---
+          Support for IO bounce buffering for systems without an IOMMU.
+          This allows us to DMA to the full physical address space on
+          platforms where the size of a physical address is larger
+          than the bus address.  Not all platforms support this.
+
 config PPC_NEED_DMA_SYNC_OPS
         def_bool y
-        depends on NOT_COHERENT_CACHE
+        depends on (NOT_COHERENT_CACHE || SWIOTLB)
 
 config HOTPLUG_CPU
         bool "Support for enabling/disabling CPUs"