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author | Marek Szyprowski <m.szyprowski@samsung.com> | 2012-03-23 12:05:14 (GMT) |
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committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2012-05-21 13:06:09 (GMT) |
commit | bca0fa5f12a6744a2b2e53154af65a51402b3426 (patch) | |
tree | 3da5a3098d9a9139e7a027cdab1a8ae5386f6be0 /drivers/base | |
parent | 76e10d158efb6d4516018846f60c2ab5501900bc (diff) | |
download | linux-bca0fa5f12a6744a2b2e53154af65a51402b3426.tar.xz |
common: add dma_mmap_from_coherent() function
Add a common helper for dma-mapping core for mapping a coherent buffer
to userspace.
Reported-by: Subash Patel <subashrp@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Diffstat (limited to 'drivers/base')
-rw-r--r-- | drivers/base/dma-coherent.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c index bb0025c..1b85949 100644 --- a/drivers/base/dma-coherent.c +++ b/drivers/base/dma-coherent.c @@ -10,6 +10,7 @@ struct dma_coherent_mem { void *virt_base; dma_addr_t device_base; + phys_addr_t pfn_base; int size; int flags; unsigned long *bitmap; @@ -44,6 +45,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr, dev->dma_mem->virt_base = mem_base; dev->dma_mem->device_base = device_addr; + dev->dma_mem->pfn_base = PFN_DOWN(bus_addr); dev->dma_mem->size = pages; dev->dma_mem->flags = flags; @@ -176,3 +178,43 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr) return 0; } EXPORT_SYMBOL(dma_release_from_coherent); + +/** + * dma_mmap_from_coherent() - try to mmap the memory allocated from + * per-device coherent memory pool to userspace + * @dev: device from which the memory was allocated + * @vma: vm_area for the userspace memory + * @vaddr: cpu address returned by dma_alloc_from_coherent + * @size: size of the memory buffer allocated by dma_alloc_from_coherent + * + * This checks whether the memory was allocated from the per-device + * coherent memory pool and if so, maps that memory to the provided vma. + * + * Returns 1 if we correctly mapped the memory, or 0 if + * dma_release_coherent() should proceed with mapping memory from + * generic pools. + */ +int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma, + void *vaddr, size_t size, int *ret) +{ + struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL; + + if (mem && vaddr >= mem->virt_base && vaddr + size <= + (mem->virt_base + (mem->size << PAGE_SHIFT))) { + unsigned long off = vma->vm_pgoff; + int start = (vaddr - mem->virt_base) >> PAGE_SHIFT; + int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; + int count = size >> PAGE_SHIFT; + + *ret = -ENXIO; + if (off < count && user_count <= count - off) { + unsigned pfn = mem->pfn_base + start + off; + *ret = remap_pfn_range(vma, vma->vm_start, pfn, + user_count << PAGE_SHIFT, + vma->vm_page_prot); + } + return 1; + } + return 0; +} +EXPORT_SYMBOL(dma_mmap_from_coherent); |