kernel/dma/dummy.c

   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 };