From e29ccc188f3dae1cb66f59e10e01e0f150642a54 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sat, 3 Aug 2019 13:31:25 +0300 Subject: dma-mapping: add a dma_can_mmap helper Add a helper to check if DMA allocations for a specific device can be mapped to userspace using dma_mmap_*. Signed-off-by: Christoph Hellwig --- kernel/dma/mapping.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'kernel/dma') diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index c8b4e46407ba..18ba1ac93fc1 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -222,6 +222,29 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, #endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */ } +/** + * dma_can_mmap - check if a given device supports dma_mmap_* + * @dev: device to check + * + * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to + * map DMA allocations to userspace. + */ +bool dma_can_mmap(struct device *dev) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + + if (IS_ENABLED(CONFIG_ARCH_NO_COHERENT_DMA_MMAP)) + return false; + + if (dma_is_direct(ops)) { + return dev_is_dma_coherent(dev) || + IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN); + } + + return ops->mmap != NULL; +} +EXPORT_SYMBOL_GPL(dma_can_mmap); + /** * dma_mmap_attrs - map a coherent DMA allocation into user space * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices -- cgit v1.2.3