[PATCH 2/3] dma: Introduce dma_max_mapping_size()
From: Joerg Roedel <joro@8bytes.org>
Date: 2019-01-15 13:23:04
Also in:
linux-iommu, lkml
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
From: Joerg Roedel <redacted> 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. Signed-off-by: Joerg Roedel <redacted> --- include/linux/dma-mapping.h | 16 ++++++++++++++++ kernel/dma/direct.c | 10 ++++++++++ 2 files changed, 26 insertions(+)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index f6ded992c183..a3ca8a71a704 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h@@ -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>
@@ -440,6 +443,19 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) return 0; } +static inline 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; +} + void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t flag, unsigned long attrs); void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 355d16acee6d..84917e1003c4 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c@@ -380,3 +380,13 @@ 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) +{ + /* + * Return the minimum of the direct DMA limit and the SWIOTLB limit. + * Since direct DMA has no limit, it is fine to just return the SWIOTLB + * limit. + */ + return swiotlb_max_mapping_size(dev); +}
--
2.17.1