powerpc: Rename get_dma_direct_offset get_dma_offset

The former is no longer really accurate with the swiotlb case now
a possibility.  I also move it into dma-mapping.h - it no longer
needs to be in dma.c, and there are about to be some more accessors
that should all end up in the same place.  A comment is added to
indicate that this function is not used in configs where there is no
simple dma offset, such as the iommu case.

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

1 files changed, 18 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index cb2ca41dd526..34b919fe8cda 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -26,7 +26,6 @@ extern void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 extern void dma_direct_free_coherent(struct device *dev, size_t size,
                                      void *vaddr, dma_addr_t dma_handle);
 
-extern unsigned long get_dma_direct_offset(struct device *dev);
 
 #ifdef CONFIG_NOT_COHERENT_CACHE
 /*
@@ -90,6 +89,22 @@ static inline void set_dma_ops(struct device *dev, struct dma_map_ops *ops)
         dev->archdata.dma_ops = ops;
 }
 
+/*
+ * get_dma_offset()
+ *
+ * Get the dma offset on configurations where the dma address can be determined
+ * from the physical address by looking at a simple offset.  Direct dma and
+ * swiotlb use this function, but it is typically not used by implementations
+ * with an iommu.
+ */
+static inline unsigned long get_dma_offset(struct device *dev)
+{
+        if (dev)
+                return (unsigned long)dev->archdata.dma_data;
+
+        return PCI_DRAM_OFFSET;
+}
+
 /* this will be removed soon */
 #define flush_write_buffers()
 
@@ -181,12 +196,12 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
-        return paddr + get_dma_direct_offset(dev);
+        return paddr + get_dma_offset(dev);
 }
 
 static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 {
-        return daddr - get_dma_direct_offset(dev);
+        return daddr - get_dma_offset(dev);
 }
 
 #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)