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1 /*
2  *	lib/dma-noop.c
3  *
4  * Simple DMA noop-ops that map 1:1 with memory
5  */
6 #include <linux/export.h>
7 #include <linux/mm.h>
8 #include <linux/dma-mapping.h>
9 #include <linux/scatterlist.h>
10 
dma_noop_alloc(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t gfp,unsigned long attrs)11 static void *dma_noop_alloc(struct device *dev, size_t size,
12 			    dma_addr_t *dma_handle, gfp_t gfp,
13 			    unsigned long attrs)
14 {
15 	void *ret;
16 
17 	ret = (void *)__get_free_pages(gfp, get_order(size));
18 	if (ret)
19 		*dma_handle = virt_to_phys(ret);
20 	return ret;
21 }
22 
dma_noop_free(struct device * dev,size_t size,void * cpu_addr,dma_addr_t dma_addr,unsigned long attrs)23 static void dma_noop_free(struct device *dev, size_t size,
24 			  void *cpu_addr, dma_addr_t dma_addr,
25 			  unsigned long attrs)
26 {
27 	free_pages((unsigned long)cpu_addr, get_order(size));
28 }
29 
dma_noop_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction dir,unsigned long attrs)30 static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
31 				      unsigned long offset, size_t size,
32 				      enum dma_data_direction dir,
33 				      unsigned long attrs)
34 {
35 	return page_to_phys(page) + offset;
36 }
37 
dma_noop_map_sg(struct device * dev,struct scatterlist * sgl,int nents,enum dma_data_direction dir,unsigned long attrs)38 static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
39 			     enum dma_data_direction dir,
40 			     unsigned long attrs)
41 {
42 	int i;
43 	struct scatterlist *sg;
44 
45 	for_each_sg(sgl, sg, nents, i) {
46 		void *va;
47 
48 		BUG_ON(!sg_page(sg));
49 		va = sg_virt(sg);
50 		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
51 		sg_dma_len(sg) = sg->length;
52 	}
53 
54 	return nents;
55 }
56 
dma_noop_mapping_error(struct device * dev,dma_addr_t dma_addr)57 static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
58 {
59 	return 0;
60 }
61 
dma_noop_supported(struct device * dev,u64 mask)62 static int dma_noop_supported(struct device *dev, u64 mask)
63 {
64 	return 1;
65 }
66 
67 struct dma_map_ops dma_noop_ops = {
68 	.alloc			= dma_noop_alloc,
69 	.free			= dma_noop_free,
70 	.map_page		= dma_noop_map_page,
71 	.map_sg			= dma_noop_map_sg,
72 	.mapping_error		= dma_noop_mapping_error,
73 	.dma_supported		= dma_noop_supported,
74 };
75 
76 EXPORT_SYMBOL(dma_noop_ops);
77