| 1 | |
| 2 | |
| 3 | * DMA operations that map to virtual addresses without flushing memory.
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| 4 |
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| 5 | #include <linux/export.h>
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| 6 | #include <linux/mm.h>
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| 7 | #include <linux/dma-mapping.h>
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| 8 | #include <linux/scatterlist.h>
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| 9 |
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| 10 | static void *dma_virt_alloc(struct device *dev, size_t size,
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| 11 | dma_addr_t *dma_handle, gfp_t gfp,
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| 12 | unsigned long attrs)
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| 13 | {
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| 14 | void *ret;
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| 15 |
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| 16 | ret = (void *)__get_free_pages(gfp | __GFP_ZERO, get_order(size));
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| 17 | if (ret)
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| 18 | *dma_handle = (uintptr_t)ret;
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| 19 | return ret;
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| 20 | }
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| 21 |
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| 22 | static void dma_virt_free(struct device *dev, size_t size,
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| 23 | void *cpu_addr, dma_addr_t dma_addr,
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| 24 | unsigned long attrs)
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| 25 | {
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| 26 | free_pages((unsigned long)cpu_addr, get_order(size));
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| 27 | }
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| 28 |
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| 29 | static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
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| 30 | unsigned long offset, size_t size,
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| 31 | enum dma_data_direction dir,
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| 32 | unsigned long attrs)
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| 33 | {
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| 34 | return (uintptr_t)(page_address(page) + offset);
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| 35 | }
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| 36 |
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| 37 | static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
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| 38 | int nents, enum dma_data_direction dir,
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| 39 | unsigned long attrs)
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| 40 | {
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| 41 | int i;
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| 42 | struct scatterlist *sg;
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| 43 |
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| 44 | for_each_sg(sgl, sg, nents, i) {
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| 45 | BUG_ON(!sg_page(sg));
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| 46 | sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
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| 47 | sg_dma_len(sg) = sg->length;
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| 48 | }
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| 49 |
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| 50 | return nents;
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| 51 | }
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| 52 |
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| 53 | const struct dma_map_ops dma_virt_ops = {
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| 54 | .alloc = dma_virt_alloc,
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| 55 | .free = dma_virt_free,
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| 56 | .map_page = dma_virt_map_page,
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| 57 | .map_sg = dma_virt_map_sg,
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| 58 | };
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| 59 | EXPORT_SYMBOL(dma_virt_ops);
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