Commit eedb0b12 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-mapping: add a dma_mmap_pages helper 



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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarTomasz Figa <tfiga@chromium.org>
Tested-by: default avatarRicardo Ribalda <ribalda@chromium.org>
parent 1e28eed1

Documentation/core-api/dma-api.rst

+10 −0
Original line number Diff line number Diff line
@@ -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 *

include/linux/dma-mapping.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

kernel/dma/mapping.c

+13 −0
Original line number Diff line number Diff line
@@ -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);