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
13static 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
26static 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
48static 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
54static 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
65struct 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
77void __init no_iommu_init(void)
78{
79	if (dma_ops)
80		return;
81	dma_ops = &nommu_dma_ops;
82}
83