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Commit 133d624b authored by Joerg Roedel's avatar Joerg Roedel Committed by Michael S. Tsirkin
Browse files

dma: Introduce dma_max_mapping_size() 



The function returns the maximum size that can be mapped
using DMA-API functions. The patch also adds the
implementation for direct DMA and a new dma_map_ops pointer
so that other implementations can expose their limit.

Cc: stable@vger.kernel.org
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 492366f7

Documentation/DMA-API.txt

+8 −0
Original line number Diff line number Diff line
@@ -195,6 +195,14 @@ Requesting the required mask does not alter the current mask. If you 
wish to take advantage of it, you should issue a dma_set_mask()

call to set the mask to the value returned.



::



	size_t

	dma_direct_max_mapping_size(struct device *dev);



Returns the maximum size of a mapping for the device. The size parameter

of the mapping functions like dma_map_single(), dma_map_page() and

others should not be larger than the returned value.



Part Id - Streaming DMA mappings

--------------------------------

include/linux/dma-mapping.h

+8 −0
Original line number Diff line number Diff line
@@ -130,6 +130,7 @@ struct dma_map_ops { 
			enum dma_data_direction direction);

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

	u64 (*get_required_mask)(struct device *dev);

	size_t (*max_mapping_size)(struct device *dev);

};



#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
@@ -257,6 +258,8 @@ static inline void dma_direct_sync_sg_for_cpu(struct device *dev, 
}

#endif



size_t dma_direct_max_mapping_size(struct device *dev);



#ifdef CONFIG_HAS_DMA

#include <asm/dma-mapping.h>
@@ -460,6 +463,7 @@ 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);

u64 dma_get_required_mask(struct device *dev);

size_t dma_max_mapping_size(struct device *dev);

#else /* CONFIG_HAS_DMA */

static inline dma_addr_t dma_map_page_attrs(struct device *dev,

		struct page *page, size_t offset, size_t size,
@@ -561,6 +565,10 @@ static inline u64 dma_get_required_mask(struct device *dev) 
{

	return 0;

}

static inline size_t dma_max_mapping_size(struct device *dev)

{

	return 0;

}

#endif /* CONFIG_HAS_DMA */



static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,

kernel/dma/direct.c

+11 −0
Original line number Diff line number Diff line
@@ -380,3 +380,14 @@ int dma_direct_supported(struct device *dev, u64 mask) 
	 */

	return mask >= __phys_to_dma(dev, min_mask);

}



size_t dma_direct_max_mapping_size(struct device *dev)

{

	size_t size = SIZE_MAX;



	/* If SWIOTLB is active, use its maximum mapping size */

	if (is_swiotlb_active())

		size = swiotlb_max_mapping_size(dev);



	return size;

}

kernel/dma/mapping.c

+14 −0
Original line number Diff line number Diff line
@@ -357,3 +357,17 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size, 
		ops->cache_sync(dev, vaddr, size, dir);

}

EXPORT_SYMBOL(dma_cache_sync);



size_t dma_max_mapping_size(struct device *dev)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);

	size_t size = SIZE_MAX;



	if (dma_is_direct(ops))

		size = dma_direct_max_mapping_size(dev);

	else if (ops && ops->max_mapping_size)

		size = ops->max_mapping_size(dev);



	return size;

}

EXPORT_SYMBOL_GPL(dma_max_mapping_size);