xref: /linux/kernel/dma/ops_helpers.c (revision f4db95b68ae68ebaf91d35cc0487ac1cbd04261e)
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