Hello, Folloing the discussion about the driver for IOMMU controller for Samsung Exynos4 platform and Arnd's suggestions I've decided to start working on redesign of dma-mapping implementation for ARM architecture. The goal is to add support for IOMMU in the way preffered by the community :) Some of the ideas about merging dma-mapping api and iommu api comes from the following threads: http://www.spinics.net/lists/linux-media/msg31453.html http://www.spinics.net/lists/arm-kernel/msg122552.html http://www.spinics.net/lists/arm-kernel/msg124416.html They were also discussed on Linaro memory management meeting at UDS (Budapest 9-12 May). I've finaly managed to clean up a bit my works and present the initial, very proof-of-concept version of patches that were ready just before Linaro meeting. What have been implemented: 1. Introduced arm_dma_ops dma_map_ops from include/linux/dma-mapping.h suffers from the following limitations: - lack of start address for sync operations - lack of write-combine methods - lack of mmap to user-space methods - lack of map_single method For the initial version I've decided to use custom arm_dma_ops. Extending common interface will take time, until that I wanted to have something already working. dma_{alloc,free,mmap}_{coherent,writecombine} have been consolidated into dma_{alloc,free,mmap}_attrib what have been suggested on Linaro meeting. New attribute for WRITE_COMBINE memory have been introduced. 2. moved all inline ARM dma-mapping related operations to arch/arm/mm/dma-mapping.c and put them as methods in generic arm_dma_ops structure. The dma-mapping.c code deinitely needs cleanup, but this is just a first step. 3. Added very initial IOMMU support. Right now it is limited only to dma_alloc_attrib, dma_free_attrib and dma_mmap_attrib. It have been tested with s5p-fimc driver on Samsung Exynos4 platform. 4. Adapted Samsung Exynos4 IOMUU driver to make use of the introduced iommu_dma proposal. This patch series contains only patches for common dma-mapping part. There is also a patch that adds driver for Samsung IOMMU controller on Exynos4 platform. All required patches are available on: git://git.infradead.org/users/kmpark/linux-2.6-samsung dma-mapping branch Git web interface: http://git.infradead.org/users/kmpark/linux-2.6-samsung/shortlog/refs/heads/dma-mapping Future: 1. Add all missing operations for IOMMU mappings (map_single/page/sg, sync_*) 2. Move sync_* operations into separate function for better code sharing between iommu and non-iommu dma-mapping code 3. Splitting out dma bounce code from non-bounce into separate set of dma methods. Right now dma-bounce code is compiled conditionally and spread over arch/arm/mm/dma-mapping.c and arch/arm/common/dmabounce.c. 4. Merging dma_map_single with dma_map_page. I haven't investigated deeply why they have separate implementation on ARM. If this is a requirement then dma_map_ops need to be extended with another method. 5. Fix dma_alloc to unmap from linear mapping. 6. Convert IO address space management code from gen-alloc to some simpler bitmap based solution. 7. resolve issues that might araise during discussion & comments Please note that this is very early version of patches, definitely NOT intended for merging. I just wanted to make sure that the direction is right and share the code with others that might want to cooperate on dma-mapping improvements. Best regards -- Marek Szyprowski Samsung Poland R&D Center Patch summary: Marek Szyprowski (2): ARM: Move dma related inlines into arm_dma_ops methods ARM: initial proof-of-concept IOMMU mapper for DMA-mapping arch/arm/Kconfig | 1 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-iommu.h | 30 ++ arch/arm/include/asm/dma-mapping.h | 653 +++++++++++------------------ arch/arm/mm/dma-mapping.c | 817 +++++++++++++++++++++++++++++++++--- arch/arm/mm/vmregion.h | 2 +- include/linux/dma-attrs.h | 1 + 7 files changed, 1033 insertions(+), 474 deletions(-) create mode 100644 arch/arm/include/asm/dma-iommu.h -- 1.7.1.569.g6f426 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>