2 files changed, 10 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/dma_64.c b/arch/powerpc/kernel/dma_64.c
index 4e6551199782..1d1dc76606ac 100644
--- a/arch/powerpc/kernel/dma_64.c
+++ b/arch/powerpc/kernel/dma_64.c
@@ -111,7 +111,11 @@ EXPORT_SYMBOL(dma_iommu_ops);
 
 /*
  * Generic direct DMA implementation
+ *
+ * This implementation supports a global offset that can be applied if
+ * the address at which memory is visible to devices is not 0.
  */
+unsigned long dma_direct_offset;
 
 static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
                                        dma_addr_t *dma_handle, gfp_t flag)
@@ -122,7 +126,7 @@ static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
         ret = (void *)__get_free_pages(flag, get_order(size));
         if (ret != NULL) {
                 memset(ret, 0, size);
-                *dma_handle = virt_to_abs(ret);
+                *dma_handle = virt_to_abs(ret) | dma_direct_offset;
         }
         return ret;
 }
@@ -137,7 +141,7 @@ static dma_addr_t dma_direct_map_single(struct device *dev, void *ptr,
                                         size_t size,
                                         enum dma_data_direction direction)
 {
-        return virt_to_abs(ptr);
+        return virt_to_abs(ptr) | dma_direct_offset;
 }
 
 static void dma_direct_unmap_single(struct device *dev, dma_addr_t dma_addr,
@@ -152,7 +156,8 @@ static int dma_direct_map_sg(struct device *dev, struct scatterlist *sg,
         int i;
 
         for (i = 0; i < nents; i++, sg++) {
-                sg->dma_address = page_to_phys(sg->page) + sg->offset;
+                sg->dma_address = (page_to_phys(sg->page) + sg->offset) |
+                        dma_direct_offset;
                 sg->dma_length = sg->length;
         }
 
diff --git a/include/asm-powerpc/dma-mapping.h b/include/asm-powerpc/dma-mapping.h
index 8367810c994c..7e38b5fddada 100644
--- a/include/asm-powerpc/dma-mapping.h
+++ b/include/asm-powerpc/dma-mapping.h
@@ -187,6 +187,8 @@ static inline void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 extern struct dma_mapping_ops dma_iommu_ops;
 extern struct dma_mapping_ops dma_direct_ops;
 
+extern unsigned long dma_direct_offset;
+
 #else /* CONFIG_PPC64 */
 
 #define dma_supported(dev, mask)        (1)