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Commit e29ccc18 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-mapping: add a dma_can_mmap helper 



Add a helper to check if DMA allocations for a specific device can be
mapped to userspace using dma_mmap_*.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent f9f3232a

include/linux/dma-mapping.h

+5 −0
Original line number Diff line number Diff line
@@ -463,6 +463,7 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, 
int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,

		void *cpu_addr, dma_addr_t dma_addr, size_t size,

		unsigned long attrs);

bool dma_can_mmap(struct device *dev);

int dma_supported(struct device *dev, u64 mask);

int dma_set_mask(struct device *dev, u64 mask);

int dma_set_coherent_mask(struct device *dev, u64 mask);
@@ -554,6 +555,10 @@ static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, 
{

	return -ENXIO;

}

static inline bool dma_can_mmap(struct device *dev)

{

	return false;

}

static inline int dma_supported(struct device *dev, u64 mask)

{

	return 0;

kernel/dma/mapping.c

+23 −0
Original line number Diff line number Diff line
@@ -222,6 +222,29 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, 
#endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */

}



/**

 * dma_can_mmap - check if a given device supports dma_mmap_*

 * @dev: device to check

 *

 * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to

 * map DMA allocations to userspace.

 */

bool dma_can_mmap(struct device *dev)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);



	if (IS_ENABLED(CONFIG_ARCH_NO_COHERENT_DMA_MMAP))

		return false;



	if (dma_is_direct(ops)) {

		return dev_is_dma_coherent(dev) ||

			IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN);

	}



	return ops->mmap != NULL;

}

EXPORT_SYMBOL_GPL(dma_can_mmap);



/**

 * dma_mmap_attrs - map a coherent DMA allocation into user space

 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices