ops_helpers.c

  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#include <linux/iommu-dma.h>
  8
  9static struct page *dma_common_vaddr_to_page(void *cpu_addr)
 10{
 11	if (is_vmalloc_addr(cpu_addr))
 12		return vmalloc_to_page(cpu_addr);
 13	return virt_to_page(cpu_addr);
 14}
 15
 16/*
 17 * Create scatter-list for the already allocated DMA buffer.
 18 */
 19int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 20		 void *cpu_addr, dma_addr_t dma_addr, size_t size,
 21		 unsigned long attrs)
 22{
 23	struct page *page = dma_common_vaddr_to_page(cpu_addr);
 24	int ret;
 25
 26	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
 27	if (!ret)
 28		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
 29	return ret;
 30}
 31
 32/*
 33 * Create userspace mapping for the DMA-coherent memory.
 34 */
 35int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 36		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 37		unsigned long attrs)
 38{
 39#ifdef CONFIG_MMU
 40	unsigned long user_count = vma_pages(vma);
 41	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 42	unsigned long off = vma->vm_pgoff;
 43	struct page *page = dma_common_vaddr_to_page(cpu_addr);
 44	int ret = -ENXIO;
 45
 46	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
 47
 48	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
 49		return ret;
 50
 51	if (off >= count || user_count > count - off)
 52		return -ENXIO;
 53
 54	return remap_pfn_range(vma, vma->vm_start,
 55			page_to_pfn(page) + vma->vm_pgoff,
 56			user_count << PAGE_SHIFT, vma->vm_page_prot);
 57#else
 58	return -ENXIO;
 59#endif /* CONFIG_MMU */
 60}
 61
 62struct page *dma_common_alloc_pages(struct device *dev, size_t size,
 63		dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
 64{
 65	const struct dma_map_ops *ops = get_dma_ops(dev);
 66	struct page *page;
 67	phys_addr_t phys;
 68
 69	page = dma_alloc_contiguous(dev, size, gfp);
 70	if (!page)
 71		page = alloc_pages_node(dev_to_node(dev), gfp, get_order(size));
 72	if (!page)
 73		return NULL;
 74
 75	phys = page_to_phys(page);
 76	if (use_dma_iommu(dev))
 77		*dma_handle = iommu_dma_map_phys(dev, phys, size, dir,
 78						 DMA_ATTR_SKIP_CPU_SYNC);
 79	else
 80		*dma_handle = ops->map_phys(dev, phys, size, dir,
 81					    DMA_ATTR_SKIP_CPU_SYNC);
 82	if (*dma_handle == DMA_MAPPING_ERROR) {
 83		dma_free_contiguous(dev, page, size);
 84		return NULL;
 85	}
 86
 87	memset(page_address(page), 0, size);
 88	return page;
 89}
 90
 91void dma_common_free_pages(struct device *dev, size_t size, struct page *page,
 92		dma_addr_t dma_handle, enum dma_data_direction dir)
 93{
 94	const struct dma_map_ops *ops = get_dma_ops(dev);
 95
 96	if (use_dma_iommu(dev))
 97		iommu_dma_unmap_phys(dev, dma_handle, size, dir,
 98				     DMA_ATTR_SKIP_CPU_SYNC);
 99	else if (ops->unmap_phys)
100		ops->unmap_phys(dev, dma_handle, size, dir,
101				DMA_ATTR_SKIP_CPU_SYNC);
102	dma_free_contiguous(dev, page, size);
103}