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 #include <linux/scatterlist.h>
9
10 #include <asm/iommu.h>
11 #include <asm/processor.h>
12 #include <asm/dma.h>
13
14 static int
check_addr(char * name,struct device * hwdev,dma_addr_t bus,size_t size)15 check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
16 {
17 if (hwdev && !is_buffer_dma_capable(*hwdev->dma_mask, bus, size)) {
18 if (*hwdev->dma_mask >= DMA_32BIT_MASK)
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
28 static dma_addr_t
nommu_map_single(struct device * hwdev,phys_addr_t paddr,size_t size,int direction)29 nommu_map_single(struct device *hwdev, phys_addr_t paddr, size_t size,
30 int direction)
31 {
32 dma_addr_t bus = paddr;
33 WARN_ON(size == 0);
34 if (!check_addr("map_single", hwdev, bus, size))
35 return bad_dma_address;
36 flush_write_buffers();
37 return bus;
38 }
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 */
nommu_map_sg(struct device * hwdev,struct scatterlist * sg,int nents,int direction)56 static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
57 int nents, int direction)
58 {
59 struct scatterlist *s;
60 int i;
61
62 WARN_ON(nents == 0 || sg[0].length == 0);
63
64 for_each_sg(sg, s, nents, i) {
65 BUG_ON(!sg_page(s));
66 s->dma_address = sg_phys(s);
67 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
68 return 0;
69 s->dma_length = s->length;
70 }
71 flush_write_buffers();
72 return nents;
73 }
74
nommu_free_coherent(struct device * dev,size_t size,void * vaddr,dma_addr_t dma_addr)75 static void nommu_free_coherent(struct device *dev, size_t size, void *vaddr,
76 dma_addr_t dma_addr)
77 {
78 free_pages((unsigned long)vaddr, get_order(size));
79 }
80
81 struct dma_mapping_ops nommu_dma_ops = {
82 .alloc_coherent = dma_generic_alloc_coherent,
83 .free_coherent = nommu_free_coherent,
84 .map_single = nommu_map_single,
85 .map_sg = nommu_map_sg,
86 .is_phys = 1,
87 };
88
no_iommu_init(void)89 void __init no_iommu_init(void)
90 {
91 if (dma_ops)
92 return;
93
94 force_iommu = 0; /* no HW IOMMU */
95 dma_ops = &nommu_dma_ops;
96 }
97