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