1 /*
2 * DMA mapping support for platforms lacking IOMMUs.
3 *
4 * Copyright (C) 2009 Paul Mundt
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 */
10 #include <linux/dma-mapping.h>
11 #include <linux/io.h>
12
nommu_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction dir,struct dma_attrs * attrs)13 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
14 unsigned long offset, size_t size,
15 enum dma_data_direction dir,
16 struct dma_attrs *attrs)
17 {
18 dma_addr_t addr = page_to_phys(page) + offset;
19
20 WARN_ON(size == 0);
21 dma_cache_sync(dev, page_address(page) + offset, size, dir);
22
23 return addr;
24 }
25
nommu_map_sg(struct device * dev,struct scatterlist * sg,int nents,enum dma_data_direction dir,struct dma_attrs * attrs)26 static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
27 int nents, enum dma_data_direction dir,
28 struct dma_attrs *attrs)
29 {
30 struct scatterlist *s;
31 int i;
32
33 WARN_ON(nents == 0 || sg[0].length == 0);
34
35 for_each_sg(sg, s, nents, i) {
36 BUG_ON(!sg_page(s));
37
38 dma_cache_sync(dev, sg_virt(s), s->length, dir);
39
40 s->dma_address = sg_phys(s);
41 s->dma_length = s->length;
42 }
43
44 return nents;
45 }
46
47 #ifdef CONFIG_DMA_NONCOHERENT
nommu_sync_single(struct device * dev,dma_addr_t addr,size_t size,enum dma_data_direction dir)48 static void nommu_sync_single(struct device *dev, dma_addr_t addr,
49 size_t size, enum dma_data_direction dir)
50 {
51 dma_cache_sync(dev, phys_to_virt(addr), size, dir);
52 }
53
nommu_sync_sg(struct device * dev,struct scatterlist * sg,int nelems,enum dma_data_direction dir)54 static void nommu_sync_sg(struct device *dev, struct scatterlist *sg,
55 int nelems, enum dma_data_direction dir)
56 {
57 struct scatterlist *s;
58 int i;
59
60 for_each_sg(sg, s, nelems, i)
61 dma_cache_sync(dev, sg_virt(s), s->length, dir);
62 }
63 #endif
64
65 struct dma_map_ops nommu_dma_ops = {
66 .alloc = dma_generic_alloc_coherent,
67 .free = dma_generic_free_coherent,
68 .map_page = nommu_map_page,
69 .map_sg = nommu_map_sg,
70 #ifdef CONFIG_DMA_NONCOHERENT
71 .sync_single_for_device = nommu_sync_single,
72 .sync_sg_for_device = nommu_sync_sg,
73 #endif
74 .is_phys = 1,
75 };
76
no_iommu_init(void)77 void __init no_iommu_init(void)
78 {
79 if (dma_ops)
80 return;
81 dma_ops = &nommu_dma_ops;
82 }
83