Commit 6ba99411 authored by Yoshihiro Shimoda's avatar Yoshihiro Shimoda Committed by Christoph Hellwig
Browse files

dma-mapping: introduce dma_get_merge_boundary() 



This patch adds a new DMA API "dma_get_merge_boundary". This function
returns the DMA merge boundary if the DMA layer can merge the segments.
This patch also adds the implementation for a new dma_map_ops pointer.

Signed-off-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: default avatarSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 38c38cb7

Documentation/DMA-API.txt

+8 −0
Original line number Original line Diff line number Diff line
@@ -204,6 +204,14 @@ 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

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

others should not be larger than the returned value.

others should not be larger than the returned value.





::



	unsigned long

	dma_get_merge_boundary(struct device *dev);



Returns the DMA merge boundary. If the device cannot merge any the DMA address

segments, the function returns 0.



Part Id - Streaming DMA mappings

Part Id - Streaming DMA mappings

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

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

include/linux/dma-mapping.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -131,6 +131,7 @@ struct dma_map_ops { 
	int (*dma_supported)(struct device *dev, u64 mask);

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

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

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

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

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

	unsigned long (*get_merge_boundary)(struct device *dev);

};

};





#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)

#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
@@ -467,6 +468,7 @@ int dma_set_mask(struct device *dev, u64 mask); 
int dma_set_coherent_mask(struct device *dev, u64 mask);

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

u64 dma_get_required_mask(struct device *dev);

u64 dma_get_required_mask(struct device *dev);

size_t dma_max_mapping_size(struct device *dev);

size_t dma_max_mapping_size(struct device *dev);

unsigned long dma_get_merge_boundary(struct device *dev);

#else /* CONFIG_HAS_DMA */

#else /* CONFIG_HAS_DMA */

static inline dma_addr_t dma_map_page_attrs(struct device *dev,

static inline dma_addr_t dma_map_page_attrs(struct device *dev,

		struct page *page, size_t offset, size_t size,

		struct page *page, size_t offset, size_t size,
@@ -572,6 +574,10 @@ static inline size_t dma_max_mapping_size(struct device *dev) 
{

{

	return 0;

	return 0;

}

}

static inline unsigned long dma_get_merge_boundary(struct device *dev)

{

	return 0;

}

#endif /* CONFIG_HAS_DMA */

#endif /* CONFIG_HAS_DMA */





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

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

kernel/dma/mapping.c

+11 −0
Original line number Original line Diff line number Diff line
@@ -407,3 +407,14 @@ size_t dma_max_mapping_size(struct device *dev) 
	return size;

	return size;

}

}

EXPORT_SYMBOL_GPL(dma_max_mapping_size);

EXPORT_SYMBOL_GPL(dma_max_mapping_size);



unsigned long dma_get_merge_boundary(struct device *dev)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);



	if (!ops || !ops->get_merge_boundary)

		return 0;	/* can't merge */



	return ops->get_merge_boundary(dev);

}

EXPORT_SYMBOL_GPL(dma_get_merge_boundary);

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