Subject: powerpc: Add an optional offset to direct DMA on 64 bits From: Benjamin Herrenschmidt This patch adds an optional global offset that can be added to DMA addresses when using the direct DMA operations. That brings it a step closer to the 32 bits direct DMA operations, and makes it useable on Cell when the MMU is disabled and we are using a spider southbridge. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Arnd Bergmann --- arch/powerpc/kernel/dma_64.c | 11 ++++++++--- include/asm-powerpc/dma-mapping.h | 2 ++ 2 files changed, 10 insertions(+), 3 deletions(-) Index: linux-2.6/arch/powerpc/kernel/dma_64.c =================================================================== --- linux-2.6.orig/arch/powerpc/kernel/dma_64.c +++ linux-2.6/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(s 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( 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 devi 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; } Index: linux-2.6/include/asm-powerpc/dma-mapping.h =================================================================== --- linux-2.6.orig/include/asm-powerpc/dma-mapping.h +++ linux-2.6/include/asm-powerpc/dma-mapping.h @@ -187,6 +187,8 @@ static inline void dma_unmap_sg(struct d 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)