Add a helper to map memory allocated using dma_alloc_pages into
a user address space, similar to the dma_alloc_attrs function for
coherent allocations.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Tested-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
Documentation/core-api/dma-api.rst | 10 ++++++++++
include/linux/dma-mapping.h | 2 ++
kernel/dma/mapping.c | 13 +++++++++++++
3 files changed, 25 insertions(+)
diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
index e6d23f117308df..157a474ae54416 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -563,6 +563,16 @@ Free a region of memory previously allocated using dma_alloc_pages().
dev, size, dma_handle and dir must all be the same as those passed into
dma_alloc_pages(). page must be the pointer returned by dma_alloc_pages().
+::
+
+ int
+ dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct page *page)
+
+Map an allocation returned from dma_alloc_pages() into a user address space.
+dev and size must be the same as those passed into dma_alloc_pages().
+page must be the pointer returned by dma_alloc_pages().
+
::
void *
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2a984cb4d1e037..2b8dce756e1fa1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -263,6 +263,8 @@ struct page *dma_alloc_pages(struct device *dev, size_t size,
dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp);
void dma_free_pages(struct device *dev, size_t size, struct page *page,
dma_addr_t dma_handle, enum dma_data_direction dir);
+int dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct page *page);
static inline void *dma_alloc_noncoherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index b6a63367993328..9ce86c77651c6f 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -517,6 +517,19 @@ void dma_free_pages(struct device *dev, size_t size, struct page *page,
}
EXPORT_SYMBOL_GPL(dma_free_pages);
+int dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct page *page)
+{
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+ if (vma->vm_pgoff >= count || vma_pages(vma) > count - vma->vm_pgoff)
+ return -ENXIO;
+ return remap_pfn_range(vma, vma->vm_start,
+ page_to_pfn(page) + vma->vm_pgoff,
+ vma_pages(vma) << PAGE_SHIFT, vma->vm_page_prot);
+}
+EXPORT_SYMBOL_GPL(dma_mmap_pages);
+
int dma_supported(struct device *dev, u64 mask)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
--
2.29.2
