There are currently no dma allocation APIs that support cached buffers. For some use cases, caching provides a signficiant performance boost that beats write-combining regions. Add apis to allocate and map a cached DMA region.
Signed-off-by: Laura Abbott <[email protected]> --- arch/arm/include/asm/dma-mapping.h | 21 +++++++++++++++++++++ arch/arm/mm/dma-mapping.c | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h index dc988ff..1565403 100644 --- a/arch/arm/include/asm/dma-mapping.h +++ b/arch/arm/include/asm/dma-mapping.h @@ -239,12 +239,33 @@ int dma_mmap_coherent(struct device *, struct vm_area_struct *, extern void *dma_alloc_writecombine(struct device *, size_t, dma_addr_t *, gfp_t); +/** + * dma_alloc_cached - allocate cached memory for DMA + * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices + * @size: required memory size + * @handle: bus-specific DMA address + * + * Allocate some cached memory for a device for + * performing DMA. This function allocates pages, and will + * return the CPU-viewed address, and sets @handle to be the + * device-viewed address. + */ +extern void *dma_alloc_cached(struct device *, size_t, dma_addr_t *, + gfp_t); + #define dma_free_writecombine(dev,size,cpu_addr,handle) \ dma_free_coherent(dev,size,cpu_addr,handle) +#define dma_free_cached(dev,size,cpu_addr,handle) \ + dma_free_coherent(dev,size,cpu_addr,handle) + int dma_mmap_writecombine(struct device *, struct vm_area_struct *, void *, dma_addr_t, size_t); + +int dma_mmap_cached(struct device *, struct vm_area_struct *, + void *, dma_addr_t, size_t); + /* * This can be called during boot to increase the size of the consistent * DMA region above it's default value of 2MB. It must be called before the diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index b1911c4..f396ddc 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -633,6 +633,20 @@ dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_ } EXPORT_SYMBOL(dma_alloc_writecombine); +/* + * Allocate a cached DMA region + */ +void * +dma_alloc_cached(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) +{ + return __dma_alloc(dev, size, handle, gfp, + pgprot_kernel, + __builtin_return_address(0)); +} +EXPORT_SYMBOL(dma_alloc_cached); + + + static int dma_mmap(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { @@ -664,6 +678,13 @@ int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma, } EXPORT_SYMBOL(dma_mmap_writecombine); +int dma_mmap_cached(struct device *dev, struct vm_area_struct *vma, + void *cpu_addr, dma_addr_t dma_addr, size_t size) +{ + return dma_mmap(dev, vma, cpu_addr, dma_addr, size); +} +EXPORT_SYMBOL(dma_mmap_cached); + /* * Free a buffer as defined by the above mapping. -- 1.7.8.3 -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
