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Commit bca0fa5f authored by Marek Szyprowski's avatar Marek Szyprowski
Browse files

common: add dma_mmap_from_coherent() function 



Add a common helper for dma-mapping core for mapping a coherent buffer
to userspace.

Reported-by: default avatarSubash Patel <subashrp@gmail.com>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Tested-By: default avatarSubash Patel <subash.ramaswamy@linaro.org>
parent 76e10d15

drivers/base/dma-coherent.c

+42 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
struct dma_coherent_mem {

	void		*virt_base;

	dma_addr_t	device_base;

	phys_addr_t	pfn_base;

	int		size;

	int		flags;

	unsigned long	*bitmap;
@@ -44,6 +45,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, 


	dev->dma_mem->virt_base = mem_base;

	dev->dma_mem->device_base = device_addr;

	dev->dma_mem->pfn_base = PFN_DOWN(bus_addr);

	dev->dma_mem->size = pages;

	dev->dma_mem->flags = flags;
@@ -176,3 +178,43 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr) 
	return 0;

}

EXPORT_SYMBOL(dma_release_from_coherent);



/**

 * dma_mmap_from_coherent() - try to mmap the memory allocated from

 * per-device coherent memory pool to userspace

 * @dev:	device from which the memory was allocated

 * @vma:	vm_area for the userspace memory

 * @vaddr:	cpu address returned by dma_alloc_from_coherent

 * @size:	size of the memory buffer allocated by dma_alloc_from_coherent

 *

 * This checks whether the memory was allocated from the per-device

 * coherent memory pool and if so, maps that memory to the provided vma.

 *

 * Returns 1 if we correctly mapped the memory, or 0 if

 * dma_release_coherent() should proceed with mapping memory from

 * generic pools.

 */

int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,

			   void *vaddr, size_t size, int *ret)

{

	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;



	if (mem && vaddr >= mem->virt_base && vaddr + size <=

		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {

		unsigned long off = vma->vm_pgoff;

		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;

		int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

		int count = size >> PAGE_SHIFT;



		*ret = -ENXIO;

		if (off < count && user_count <= count - off) {

			unsigned pfn = mem->pfn_base + start + off;

			*ret = remap_pfn_range(vma, vma->vm_start, pfn,

					       user_count << PAGE_SHIFT,

					       vma->vm_page_prot);

		}

		return 1;

	}

	return 0;

}

EXPORT_SYMBOL(dma_mmap_from_coherent);

include/asm-generic/dma-coherent.h

+3 −1
Original line number Diff line number Diff line
@@ -3,13 +3,15 @@ 


#ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT

/*

 * These two functions are only for dma allocator.

 * These three functions are only for dma allocator.

 * Don't use them in device drivers.

 */

int dma_alloc_from_coherent(struct device *dev, ssize_t size,

				       dma_addr_t *dma_handle, void **ret);

int dma_release_from_coherent(struct device *dev, int order, void *vaddr);



int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,

			    void *cpu_addr, size_t size, int *ret);

/*

 * Standard interface

 */