[PATCH 1/6] dma-mapping: add a dma_mmap_pages helper
From: Christoph Hellwig <hch@lst.de>
Date: 2021-03-01 08:58:40
Also in:
linux-iommu, linux-media, lkml
Subsystem:
dma mapping helpers, documentation, the rest · Maintainers:
Marek Szyprowski, Jonathan Corbet, Linus Torvalds
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@lst.de> Reviewed-by: Tomasz Figa <tfiga@chromium.org> Tested-by: Ricardo Ribalda <redacted> --- 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