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Commit | Line | Data |
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1 | /* | |
2 | * lib/dma-noop.c | |
3 | * | |
4 | * DMA operations that map to physical addresses without flushing memory. | |
5 | */ | |
6 | #include <linux/export.h> | |
7 | #include <linux/mm.h> | |
8 | #include <linux/dma-mapping.h> | |
9 | #include <linux/scatterlist.h> | |
10 | #include <linux/pfn.h> | |
11 | ||
12 | static void *dma_noop_alloc(struct device *dev, size_t size, | |
13 | dma_addr_t *dma_handle, gfp_t gfp, | |
14 | unsigned long attrs) | |
15 | { | |
16 | void *ret; | |
17 | ||
18 | ret = (void *)__get_free_pages(gfp, get_order(size)); | |
19 | if (ret) | |
20 | *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); | |
21 | ||
22 | return ret; | |
23 | } | |
24 | ||
25 | static void dma_noop_free(struct device *dev, size_t size, | |
26 | void *cpu_addr, dma_addr_t dma_addr, | |
27 | unsigned long attrs) | |
28 | { | |
29 | free_pages((unsigned long)cpu_addr, get_order(size)); | |
30 | } | |
31 | ||
32 | static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page, | |
33 | unsigned long offset, size_t size, | |
34 | enum dma_data_direction dir, | |
35 | unsigned long attrs) | |
36 | { | |
37 | return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset); | |
38 | } | |
39 | ||
40 | static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents, | |
41 | enum dma_data_direction dir, | |
42 | unsigned long attrs) | |
43 | { | |
44 | int i; | |
45 | struct scatterlist *sg; | |
46 | ||
47 | for_each_sg(sgl, sg, nents, i) { | |
48 | dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset); | |
49 | void *va; | |
50 | ||
51 | BUG_ON(!sg_page(sg)); | |
52 | va = sg_virt(sg); | |
53 | sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset; | |
54 | sg_dma_len(sg) = sg->length; | |
55 | } | |
56 | ||
57 | return nents; | |
58 | } | |
59 | ||
60 | const struct dma_map_ops dma_noop_ops = { | |
61 | .alloc = dma_noop_alloc, | |
62 | .free = dma_noop_free, | |
63 | .map_page = dma_noop_map_page, | |
64 | .map_sg = dma_noop_map_sg, | |
65 | }; | |
66 | ||
67 | EXPORT_SYMBOL(dma_noop_ops); |