1/* Fallback functions when the main IOMMU code is not compiled in. This
2   code is roughly equivalent to i386. */
3#include <linux/dma-mapping.h>
4#include <linux/scatterlist.h>
5#include <linux/string.h>
6#include <linux/gfp.h>
7#include <linux/pci.h>
8#include <linux/mm.h>
9
10#include <asm/processor.h>
11#include <asm/iommu.h>
12#include <asm/dma.h>
13
14static int
15check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
16{
17	if (hwdev && !dma_capable(hwdev, bus, size)) {
18		if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
19			printk(KERN_ERR
20			    "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
21				name, (long long)bus, size,
22				(long long)*hwdev->dma_mask);
23		return 0;
24	}
25	return 1;
26}
27
28static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
29				 unsigned long offset, size_t size,
30				 enum dma_data_direction dir,
31				 struct dma_attrs *attrs)
32{
33	dma_addr_t bus = page_to_phys(page) + offset;
34	WARN_ON(size == 0);
35	if (!check_addr("map_single", dev, bus, size))
36		return DMA_ERROR_CODE;
37	flush_write_buffers();
38	return bus;
39}
40
41/* Map a set of buffers described by scatterlist in streaming
42 * mode for DMA.  This is the scatter-gather version of the
43 * above pci_map_single interface.  Here the scatter gather list
44 * elements are each tagged with the appropriate dma address
45 * and length.  They are obtained via sg_dma_{address,length}(SG).
46 *
47 * NOTE: An implementation may be able to use a smaller number of
48 *       DMA address/length pairs than there are SG table elements.
49 *       (for example via virtual mapping capabilities)
50 *       The routine returns the number of addr/length pairs actually
51 *       used, at most nents.
52 *
53 * Device ownership issues as mentioned above for pci_map_single are
54 * the same here.
55 */
56static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
57			int nents, enum dma_data_direction dir,
58			struct dma_attrs *attrs)
59{
60	struct scatterlist *s;
61	int i;
62
63	WARN_ON(nents == 0 || sg[0].length == 0);
64
65	for_each_sg(sg, s, nents, i) {
66		BUG_ON(!sg_page(s));
67		s->dma_address = sg_phys(s);
68		if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
69			return 0;
70		s->dma_length = s->length;
71	}
72	flush_write_buffers();
73	return nents;
74}
75
76static void nommu_sync_single_for_device(struct device *dev,
77			dma_addr_t addr, size_t size,
78			enum dma_data_direction dir)
79{
80	flush_write_buffers();
81}
82
83
84static void nommu_sync_sg_for_device(struct device *dev,
85			struct scatterlist *sg, int nelems,
86			enum dma_data_direction dir)
87{
88	flush_write_buffers();
89}
90
91struct dma_map_ops nommu_dma_ops = {
92	.alloc			= dma_generic_alloc_coherent,
93	.free			= dma_generic_free_coherent,
94	.map_sg			= nommu_map_sg,
95	.map_page		= nommu_map_page,
96	.sync_single_for_device = nommu_sync_single_for_device,
97	.sync_sg_for_device	= nommu_sync_sg_for_device,
98	.is_phys		= 1,
99};
100