1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Dummy DMA ops that always fail. 4 */ 5 #include <linux/dma-map-ops.h> 6 7 static int dma_dummy_mmap(struct device *dev, struct vm_area_struct *vma, 8 void *cpu_addr, dma_addr_t dma_addr, size_t size, 9 unsigned long attrs) 10 { 11 return -ENXIO; 12 } 13 14 static dma_addr_t dma_dummy_map_page(struct device *dev, struct page *page, 15 unsigned long offset, size_t size, enum dma_data_direction dir, 16 unsigned long attrs) 17 { 18 return DMA_MAPPING_ERROR; 19 } 20 static void dma_dummy_unmap_page(struct device *dev, dma_addr_t dma_handle, 21 size_t size, enum dma_data_direction dir, unsigned long attrs) 22 { 23 /* 24 * Dummy ops doesn't support map_page, so unmap_page should never be 25 * called. 26 */ 27 WARN_ON_ONCE(true); 28 } 29 30 static int dma_dummy_map_sg(struct device *dev, struct scatterlist *sgl, 31 int nelems, enum dma_data_direction dir, 32 unsigned long attrs) 33 { 34 return -EINVAL; 35 } 36 37 static void dma_dummy_unmap_sg(struct device *dev, struct scatterlist *sgl, 38 int nelems, enum dma_data_direction dir, 39 unsigned long attrs) 40 { 41 /* 42 * Dummy ops doesn't support map_sg, so unmap_sg should never be called. 43 */ 44 WARN_ON_ONCE(true); 45 } 46 47 static int dma_dummy_supported(struct device *hwdev, u64 mask) 48 { 49 return 0; 50 } 51 52 const struct dma_map_ops dma_dummy_ops = { 53 .mmap = dma_dummy_mmap, 54 .map_page = dma_dummy_map_page, 55 .unmap_page = dma_dummy_unmap_page, 56 .map_sg = dma_dummy_map_sg, 57 .unmap_sg = dma_dummy_unmap_sg, 58 .dma_supported = dma_dummy_supported, 59 }; 60