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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
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2 | /* |
3 | * lib/dma-noop.c | |
4 | * | |
1eec9e2b | 5 | * DMA operations that map to physical addresses without flushing memory. |
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6 | */ |
7 | #include <linux/export.h> | |
8 | #include <linux/mm.h> | |
9 | #include <linux/dma-mapping.h> | |
10 | #include <linux/scatterlist.h> | |
25f1e188 | 11 | #include <linux/pfn.h> |
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12 | |
13 | static void *dma_noop_alloc(struct device *dev, size_t size, | |
14 | dma_addr_t *dma_handle, gfp_t gfp, | |
00085f1e | 15 | unsigned long attrs) |
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16 | { |
17 | void *ret; | |
18 | ||
19 | ret = (void *)__get_free_pages(gfp, get_order(size)); | |
20 | if (ret) | |
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21 | *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); |
22 | ||
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23 | return ret; |
24 | } | |
25 | ||
26 | static void dma_noop_free(struct device *dev, size_t size, | |
27 | void *cpu_addr, dma_addr_t dma_addr, | |
00085f1e | 28 | unsigned long attrs) |
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29 | { |
30 | free_pages((unsigned long)cpu_addr, get_order(size)); | |
31 | } | |
32 | ||
33 | static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page, | |
34 | unsigned long offset, size_t size, | |
35 | enum dma_data_direction dir, | |
00085f1e | 36 | unsigned long attrs) |
a8463d4b | 37 | { |
25f1e188 | 38 | return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset); |
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39 | } |
40 | ||
41 | static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents, | |
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42 | enum dma_data_direction dir, |
43 | unsigned long attrs) | |
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44 | { |
45 | int i; | |
46 | struct scatterlist *sg; | |
47 | ||
48 | for_each_sg(sgl, sg, nents, i) { | |
25f1e188 | 49 | dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset); |
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50 | void *va; |
51 | ||
52 | BUG_ON(!sg_page(sg)); | |
53 | va = sg_virt(sg); | |
25f1e188 | 54 | sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset; |
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55 | sg_dma_len(sg) = sg->length; |
56 | } | |
57 | ||
58 | return nents; | |
59 | } | |
60 | ||
5299709d | 61 | const struct dma_map_ops dma_noop_ops = { |
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62 | .alloc = dma_noop_alloc, |
63 | .free = dma_noop_free, | |
64 | .map_page = dma_noop_map_page, | |
65 | .map_sg = dma_noop_map_sg, | |
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66 | }; |
67 | ||
68 | EXPORT_SYMBOL(dma_noop_ops); |