root/kernel/dma/dummy.c

DEFINITIONS

1. dma_dummy_mmap
2. dma_dummy_map_page
3. dma_dummy_map_sg
4. dma_dummy_supported

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Dummy DMA ops that always fail.
   4  */
   5 #include <linux/dma-mapping.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 
  21 static int dma_dummy_map_sg(struct device *dev, struct scatterlist *sgl,
  22                 int nelems, enum dma_data_direction dir,
  23                 unsigned long attrs)
  24 {
  25         return 0;
  26 }
  27 
  28 static int dma_dummy_supported(struct device *hwdev, u64 mask)
  29 {
  30         return 0;
  31 }
  32 
  33 const struct dma_map_ops dma_dummy_ops = {
  34         .mmap                   = dma_dummy_mmap,
  35         .map_page               = dma_dummy_map_page,
  36         .map_sg                 = dma_dummy_map_sg,
  37         .dma_supported          = dma_dummy_supported,
  38 };
  39 EXPORT_SYMBOL(dma_dummy_ops);