1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * DMA operations that map to virtual addresses without flushing memory.
4 */
5 #include <linux/export.h>
6 #include <linux/mm.h>
7 #include <linux/dma-mapping.h>
8 #include <linux/scatterlist.h>
9
dma_virt_alloc(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t gfp,unsigned long attrs)10 static void *dma_virt_alloc(struct device *dev, size_t size,
11 dma_addr_t *dma_handle, gfp_t gfp,
12 unsigned long attrs)
13 {
14 void *ret;
15
16 ret = (void *)__get_free_pages(gfp | __GFP_ZERO, get_order(size));
17 if (ret)
18 *dma_handle = (uintptr_t)ret;
19 return ret;
20 }
21
dma_virt_free(struct device * dev,size_t size,void * cpu_addr,dma_addr_t dma_addr,unsigned long attrs)22 static void dma_virt_free(struct device *dev, size_t size,
23 void *cpu_addr, dma_addr_t dma_addr,
24 unsigned long attrs)
25 {
26 free_pages((unsigned long)cpu_addr, get_order(size));
27 }
28
dma_virt_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction dir,unsigned long attrs)29 static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
30 unsigned long offset, size_t size,
31 enum dma_data_direction dir,
32 unsigned long attrs)
33 {
34 return (uintptr_t)(page_address(page) + offset);
35 }
36
dma_virt_map_sg(struct device * dev,struct scatterlist * sgl,int nents,enum dma_data_direction dir,unsigned long attrs)37 static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
38 int nents, enum dma_data_direction dir,
39 unsigned long attrs)
40 {
41 int i;
42 struct scatterlist *sg;
43
44 for_each_sg(sgl, sg, nents, i) {
45 BUG_ON(!sg_page(sg));
46 sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
47 sg_dma_len(sg) = sg->length;
48 }
49
50 return nents;
51 }
52
53 const struct dma_map_ops dma_virt_ops = {
54 .alloc = dma_virt_alloc,
55 .free = dma_virt_free,
56 .map_page = dma_virt_map_page,
57 .map_sg = dma_virt_map_sg,
58 };
59 EXPORT_SYMBOL(dma_virt_ops);
60
