Add a new API to check if calls to dma_sync_single_for_{device,cpu} are
required for a given DMA streaming mapping.
Signed-off-by: Christoph Hellwig <h...@lst.de>
---
Documentation/core-api/dma-api.rst | 8 ++++++++
include/linux/dma-direct.h | 1 +
include/linux/dma-mapping.h | 5 +++++
kernel/dma/direct.c | 6 ++++++
kernel/dma/mapping.c | 10 ++++++++++
5 files changed, 30 insertions(+)
diff --git a/Documentation/core-api/dma-api.rst
b/Documentation/core-api/dma-api.rst
index 2d8d2fed731720..f41620439ef349 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -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.
+::
+
+ bool
+ dma_need_sync(struct device *dev, dma_addr_t dma_addr);
+
+Returns %true if dma_sync_single_for_{device,cpu} calls are required to
+transfer memory ownership. Returns %false if those calls can be skipped.
+
::
unsigned long
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index cdfa400f89b3d3..5184735a0fe8eb 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -85,4 +85,5 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct
*vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs);
int dma_direct_supported(struct device *dev, u64 mask);
+bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr);
#endif /* _LINUX_DMA_DIRECT_H */
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 78f677cf45ab69..a33ed3954ed465 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -461,6 +461,7 @@ 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);
+bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
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,
@@ -571,6 +572,10 @@ static inline size_t dma_max_mapping_size(struct device
*dev)
{
return 0;
}
+static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
+{
+ return false;
+}
static inline unsigned long dma_get_merge_boundary(struct device *dev)
{
return 0;
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 93f578a8e613ba..95866b64758100 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -539,3 +539,9 @@ size_t dma_direct_max_mapping_size(struct device *dev)
return swiotlb_max_mapping_size(dev);
return SIZE_MAX;
}
+
+bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr)
+{
+ return !dev_is_dma_coherent(dev) ||
+ is_swiotlb_buffer(dma_to_phys(dev, dma_addr));
+}
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 98e3d873792ea4..a8c18c9a796fdc 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -397,6 +397,16 @@ size_t dma_max_mapping_size(struct device *dev)
}
EXPORT_SYMBOL_GPL(dma_max_mapping_size);
+bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ if (dma_is_direct(ops))
+ return dma_direct_need_sync(dev, dma_addr);
+ return ops->sync_single_for_cpu || ops->sync_single_for_device;
+}
+EXPORT_SYMBOL_GPL(dma_need_sync);
+
unsigned long dma_get_merge_boundary(struct device *dev)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
--
2.26.2
