diff options
| -rw-r--r-- | Documentation/DMA-API.txt | 8 | ||||
| -rw-r--r-- | include/linux/dma-mapping.h | 6 | ||||
| -rw-r--r-- | kernel/dma/mapping.c | 11 |
3 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index e47c63bd4887..9c4dd3d779ed 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -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 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 -------------------------------- diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 48ebe8295987..de41a4f0b9f6 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -131,6 +131,7 @@ struct dma_map_ops { int (*dma_supported)(struct device *dev, u64 mask); u64 (*get_required_mask)(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) @@ -467,6 +468,7 @@ 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); +unsigned long dma_get_merge_boundary(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, @@ -572,6 +574,10 @@ static inline size_t dma_max_mapping_size(struct device *dev) { return 0; } +static inline unsigned long dma_get_merge_boundary(struct device *dev) +{ + return 0; +} #endif /* CONFIG_HAS_DMA */ static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 1b96616c9f20..72c825c1788e 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -407,3 +407,14 @@ size_t dma_max_mapping_size(struct device *dev) return 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); |