From 6ba99411b858bd70bae966633561e698cd6de38c Mon Sep 17 00:00:00 2001 From: Yoshihiro Shimoda Date: Wed, 28 Aug 2019 21:35:40 +0900 Subject: [PATCH] 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: Yoshihiro Shimoda Reviewed-by: Simon Horman Signed-off-by: Christoph Hellwig --- Documentation/DMA-API.txt | 8 ++++++++ include/linux/dma-mapping.h | 6 ++++++ kernel/dma/mapping.c | 11 +++++++++++ 3 files changed, 25 insertions(+) diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index e47c63b..9c4dd3d 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 48ebe829..de41a4f 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 1b96616..72c825c 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); -- 2.7.4