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
10static 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
22static 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
29static 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
37static 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
53const 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};
59EXPORT_SYMBOL(dma_virt_ops);