1/* Fallback functions when the main IOMMU code is not compiled in. This
2   code is roughly equivalent to i386. */
3#include <linux/mm.h>
4#include <linux/init.h>
5#include <linux/pci.h>
6#include <linux/string.h>
7#include <linux/dma-mapping.h>
8
9#include <asm/proto.h>
10#include <asm/processor.h>
11#include <asm/dma.h>
12
13static int
14check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
15{
16        if (hwdev && bus + size > *hwdev->dma_mask) {
17		if (*hwdev->dma_mask >= DMA_32BIT_MASK)
18			printk(KERN_ERR
19			    "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
20				name, (long long)bus, size,
21				(long long)*hwdev->dma_mask);
22		return 0;
23	}
24	return 1;
25}
26
27static dma_addr_t
28nommu_map_single(struct device *hwdev, void *ptr, size_t size,
29	       int direction)
30{
31	dma_addr_t bus = virt_to_bus(ptr);
32	if (!check_addr("map_single", hwdev, bus, size))
33				return bad_dma_address;
34	return bus;
35}
36
37void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
38			int direction)
39{
40}
41
42/* Map a set of buffers described by scatterlist in streaming
43 * mode for DMA.  This is the scatter-gather version of the
44 * above pci_map_single interface.  Here the scatter gather list
45 * elements are each tagged with the appropriate dma address
46 * and length.  They are obtained via sg_dma_{address,length}(SG).
47 *
48 * NOTE: An implementation may be able to use a smaller number of
49 *       DMA address/length pairs than there are SG table elements.
50 *       (for example via virtual mapping capabilities)
51 *       The routine returns the number of addr/length pairs actually
52 *       used, at most nents.
53 *
54 * Device ownership issues as mentioned above for pci_map_single are
55 * the same here.
56 */
57int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
58	       int nents, int direction)
59{
60	int i;
61
62 	for (i = 0; i < nents; i++ ) {
63		struct scatterlist *s = &sg[i];
64		BUG_ON(!s->page);
65		s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
66		if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
67			return 0;
68		s->dma_length = s->length;
69	}
70	return nents;
71}
72
73/* Unmap a set of streaming mode DMA translations.
74 * Again, cpu read rules concerning calls here are the same as for
75 * pci_unmap_single() above.
76 */
77void nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
78		  int nents, int dir)
79{
80}
81
82const struct dma_mapping_ops nommu_dma_ops = {
83	.map_single = nommu_map_single,
84	.unmap_single = nommu_unmap_single,
85	.map_sg = nommu_map_sg,
86	.unmap_sg = nommu_unmap_sg,
87	.is_phys = 1,
88};
89
90void __init no_iommu_init(void)
91{
92	if (dma_ops)
93		return;
94
95	force_iommu = 0; /* no HW IOMMU */
96	dma_ops = &nommu_dma_ops;
97}
98