From 1299b0e05e106f621fff1504df5251f2a678097e Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Fri, 21 Mar 2014 18:44:06 +0800 Subject: MIPS: Loongson: Add swiotlb to support All-Memory DMA Loongson doesn't support DMA address above 4GB traditionally. If memory is more than 4GB, CONFIG_SWIOTLB and ZONE_DMA32 should be selected. In this way, DMA pages are allocated below 4GB preferably. However, if low memory is not enough, high pages are allocated and swiotlb is used for bouncing. Moreover, we provide a platform-specific dma_map_ops::set_dma_mask() to set a device's dma_mask and coherent_dma_mask. We use these masks to distinguishes an allocated page can be used for DMA directly, or need swiotlb to bounce. Recently, we found that 32-bit DMA isn't a hardware bug, but a hardware configuration issue. So, latest firmware has enable the DMA support as high as 40-bit. To support all-memory DMA for all devices (besides the Loongson platform limit, there are still some devices have their own DMA32 limit), and also to be compatible with old firmware, we keep use swiotlb. Signed-off-by: Huacai Chen Signed-off-by: Hongliang Tao Signed-off-by: Hua Yan Tested-by: Alex Smith Reviewed-by: Alex Smith Cc: John Crispin Cc: Steven J. Hill Cc: Aurelien Jarno Cc: linux-mips@linux-mips.org Cc: Fuxin Zhang Cc: Zhangjin Wu Patchwork: https://patchwork.linux-mips.org/patch/6636 Signed-off-by: Ralf Baechle --- arch/mips/include/asm/dma-mapping.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/mips/include/asm/dma-mapping.h') diff --git a/arch/mips/include/asm/dma-mapping.h b/arch/mips/include/asm/dma-mapping.h index 84238c574d5..06412aa9e3f 100644 --- a/arch/mips/include/asm/dma-mapping.h +++ b/arch/mips/include/asm/dma-mapping.h @@ -49,9 +49,14 @@ static inline int dma_mapping_error(struct device *dev, u64 mask) static inline int dma_set_mask(struct device *dev, u64 mask) { + struct dma_map_ops *ops = get_dma_ops(dev); + if(!dev->dma_mask || !dma_supported(dev, mask)) return -EIO; + if (ops->set_dma_mask) + return ops->set_dma_mask(dev, mask); + *dev->dma_mask = mask; return 0; -- cgit v1.2.3-70-g09d2