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dma: Introduce dma_max_mapping_size()

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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: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Joerg Roedel 2019-02-07 12:59:15 +01:00 committed by Michael S. Tsirkin
parent 492366f7b4
commit 133d624b1c
4 changed files with 41 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

8
Documentation/DMA-API.txt
View file

@ -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
--------------------------------

8
include/linux/dma-mapping.h
View file

@ -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,

11
kernel/dma/direct.c
View file

@ -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;
}

14
kernel/dma/mapping.c
View file

@ -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);