tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * lib/dma-virt.c
4 *
5 * DMA operations that map to virtual addresses without flushing memory.
6 */
7#include <linux/export.h>
8#include <linux/mm.h>
9#include <linux/dma-mapping.h>
10#include <linux/scatterlist.h>
11
12static void *dma_virt_alloc(struct device *dev, size_t size,
13 dma_addr_t *dma_handle, gfp_t gfp,
14 unsigned long attrs)
15{
16 void *ret;
17
18 ret = (void *)__get_free_pages(gfp, get_order(size));
19 if (ret)
20 *dma_handle = (uintptr_t)ret;
21 return ret;
22}
23
24static void dma_virt_free(struct device *dev, size_t size,
25 void *cpu_addr, dma_addr_t dma_addr,
26 unsigned long attrs)
27{
28 free_pages((unsigned long)cpu_addr, get_order(size));
29}
30
31static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
32 unsigned long offset, size_t size,
33 enum dma_data_direction dir,
34 unsigned long attrs)
35{
36 return (uintptr_t)(page_address(page) + offset);
37}
38
39static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
40 int nents, enum dma_data_direction dir,
41 unsigned long attrs)
42{
43 int i;
44 struct scatterlist *sg;
45
46 for_each_sg(sgl, sg, nents, i) {
47 BUG_ON(!sg_page(sg));
48 sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
49 sg_dma_len(sg) = sg->length;
50 }
51
52 return nents;
53}
54
55const struct dma_map_ops dma_virt_ops = {
56 .alloc = dma_virt_alloc,
57 .free = dma_virt_free,
58 .map_page = dma_virt_map_page,
59 .map_sg = dma_virt_map_sg,
60};
61EXPORT_SYMBOL(dma_virt_ops);