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#include <asm/cacheflush.h>
13
14static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
15				 unsigned long offset, size_t size,
16				 enum dma_data_direction dir,
17				 unsigned long attrs)
18{
19	dma_addr_t addr = page_to_phys(page) + offset
20		- PFN_PHYS(dev->dma_pfn_offset);
21
22	WARN_ON(size == 0);
23
24	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
25		sh_sync_dma_for_device(page_address(page) + offset, size, dir);
26
27	return addr;
28}
29
30static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
31			int nents, enum dma_data_direction dir,
32			unsigned long attrs)
33{
34	struct scatterlist *s;
35	int i;
36
37	WARN_ON(nents == 0 || sg[0].length == 0);
38
39	for_each_sg(sg, s, nents, i) {
40		dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset);
41
42		BUG_ON(!sg_page(s));
43
44		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
45			sh_sync_dma_for_device(sg_virt(s), s->length, dir);
46
47		s->dma_address = sg_phys(s) - offset;
48		s->dma_length = s->length;
49	}
50
51	return nents;
52}
53
54#ifdef CONFIG_DMA_NONCOHERENT
55static void nommu_sync_single_for_device(struct device *dev, dma_addr_t addr,
56			      size_t size, enum dma_data_direction dir)
57{
58	sh_sync_dma_for_device(phys_to_virt(addr), size, dir);
59}
60
61static void nommu_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
62			  int nelems, enum dma_data_direction dir)
63{
64	struct scatterlist *s;
65	int i;
66
67	for_each_sg(sg, s, nelems, i)
68		sh_sync_dma_for_device(sg_virt(s), s->length, dir);
69}
70#endif
71
72const struct dma_map_ops nommu_dma_ops = {
73	.alloc			= dma_generic_alloc_coherent,
74	.free			= dma_generic_free_coherent,
75	.map_page		= nommu_map_page,
76	.map_sg			= nommu_map_sg,
77#ifdef CONFIG_DMA_NONCOHERENT
78	.sync_single_for_device	= nommu_sync_single_for_device,
79	.sync_sg_for_device	= nommu_sync_sg_for_device,
80#endif
81	.is_phys		= 1,
82};
83
84void __init no_iommu_init(void)
85{
86	if (dma_ops)
87		return;
88	dma_ops = &nommu_dma_ops;
89}