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 9 static 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 */ 19 int 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 */ 35 int 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 62 struct 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 68 page = dma_alloc_contiguous(dev, size, gfp); 69 if (!page) 70 page = alloc_pages_node(dev_to_node(dev), gfp, get_order(size)); 71 if (!page) 72 return NULL; 73 74 if (use_dma_iommu(dev)) 75 *dma_handle = iommu_dma_map_page(dev, page, 0, size, dir, 76 DMA_ATTR_SKIP_CPU_SYNC); 77 else 78 *dma_handle = ops->map_page(dev, page, 0, size, dir, 79 DMA_ATTR_SKIP_CPU_SYNC); 80 if (*dma_handle == DMA_MAPPING_ERROR) { 81 dma_free_contiguous(dev, page, size); 82 return NULL; 83 } 84 85 memset(page_address(page), 0, size); 86 return page; 87 } 88 89 void dma_common_free_pages(struct device *dev, size_t size, struct page *page, 90 dma_addr_t dma_handle, enum dma_data_direction dir) 91 { 92 const struct dma_map_ops *ops = get_dma_ops(dev); 93 94 if (use_dma_iommu(dev)) 95 iommu_dma_unmap_page(dev, dma_handle, size, dir, 96 DMA_ATTR_SKIP_CPU_SYNC); 97 else if (ops->unmap_page) 98 ops->unmap_page(dev, dma_handle, size, dir, 99 DMA_ATTR_SKIP_CPU_SYNC); 100 dma_free_contiguous(dev, page, size); 101 } 102