ops_helpers.c 2.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * Helpers for DMA ops implementations. These generally rely on the fact that
  4. * the allocated memory contains normal pages in the direct kernel mapping.
  5. */
  6. #include <linux/dma-map-ops.h>
  7. static struct page *dma_common_vaddr_to_page(void *cpu_addr)
  8. {
  9. if (is_vmalloc_addr(cpu_addr))
  10. return vmalloc_to_page(cpu_addr);
  11. return virt_to_page(cpu_addr);
  12. }
  13. /*
  14. * Create scatter-list for the already allocated DMA buffer.
  15. */
  16. int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
  17. void *cpu_addr, dma_addr_t dma_addr, size_t size,
  18. unsigned long attrs)
  19. {
  20. struct page *page = dma_common_vaddr_to_page(cpu_addr);
  21. int ret;
  22. ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
  23. if (!ret)
  24. sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
  25. return ret;
  26. }
  27. EXPORT_SYMBOL_GPL(dma_common_get_sgtable);
  28. /*
  29. * Create userspace mapping for the DMA-coherent memory.
  30. */
  31. int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
  32. void *cpu_addr, dma_addr_t dma_addr, size_t size,
  33. unsigned long attrs)
  34. {
  35. #ifdef CONFIG_MMU
  36. unsigned long user_count = vma_pages(vma);
  37. unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
  38. unsigned long off = vma->vm_pgoff;
  39. struct page *page = dma_common_vaddr_to_page(cpu_addr);
  40. int ret = -ENXIO;
  41. vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
  42. if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
  43. return ret;
  44. if (off >= count || user_count > count - off)
  45. return -ENXIO;
  46. return remap_pfn_range(vma, vma->vm_start,
  47. page_to_pfn(page) + vma->vm_pgoff,
  48. user_count << PAGE_SHIFT, vma->vm_page_prot);
  49. #else
  50. return -ENXIO;
  51. #endif /* CONFIG_MMU */
  52. }
  53. EXPORT_SYMBOL_GPL(dma_common_mmap);
  54. struct page *dma_common_alloc_pages(struct device *dev, size_t size,
  55. dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
  56. {
  57. const struct dma_map_ops *ops = get_dma_ops(dev);
  58. struct page *page;
  59. page = dma_alloc_contiguous(dev, size, gfp);
  60. if (!page)
  61. page = alloc_pages_node(dev_to_node(dev), gfp, get_order(size));
  62. if (!page)
  63. return NULL;
  64. *dma_handle = ops->map_page(dev, page, 0, size, dir,
  65. DMA_ATTR_SKIP_CPU_SYNC);
  66. if (*dma_handle == DMA_MAPPING_ERROR) {
  67. dma_free_contiguous(dev, page, size);
  68. return NULL;
  69. }
  70. memset(page_address(page), 0, size);
  71. return page;
  72. }
  73. void dma_common_free_pages(struct device *dev, size_t size, struct page *page,
  74. dma_addr_t dma_handle, enum dma_data_direction dir)
  75. {
  76. const struct dma_map_ops *ops = get_dma_ops(dev);
  77. if (ops->unmap_page)
  78. ops->unmap_page(dev, dma_handle, size, dir,
  79. DMA_ATTR_SKIP_CPU_SYNC);
  80. dma_free_contiguous(dev, page, size);
  81. }