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Subject[PATCH 5.0 124/238] dma: Introduce dma_max_mapping_size()
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

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

From: Joerg Roedel <jroedel@suse.de>

commit 133d624b1cee16906134e92d5befb843b58bcf31 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
Documentation/DMA-API.txt | 8 ++++++++
include/linux/dma-mapping.h | 8 ++++++++
kernel/dma/direct.c | 11 +++++++++++
kernel/dma/mapping.c | 14 ++++++++++++++
4 files changed, 41 insertions(+)

--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -195,6 +195,14 @@ Requesting the required mask does not al
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
--------------------------------
--- 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_fo
}
#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, u6
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(
{
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,
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -380,3 +380,14 @@ int dma_direct_supported(struct device *
*/
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;
+}
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -357,3 +357,17 @@ void dma_cache_sync(struct device *dev,
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);

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