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-noop.c
4 *
5 * DMA operations that map to physical 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#include <linux/pfn.h>
12
13static void *dma_noop_alloc(struct device *dev, size_t size,
14 dma_addr_t *dma_handle, gfp_t gfp,
15 unsigned long attrs)
16{
17 void *ret;
18
19 ret = (void *)__get_free_pages(gfp, get_order(size));
20 if (ret)
21 *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
22
23 return ret;
24}
25
26static void dma_noop_free(struct device *dev, size_t size,
27 void *cpu_addr, dma_addr_t dma_addr,
28 unsigned long attrs)
29{
30 free_pages((unsigned long)cpu_addr, get_order(size));
31}
32
33static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
34 unsigned long offset, size_t size,
35 enum dma_data_direction dir,
36 unsigned long attrs)
37{
38 return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
39}
40
41static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
42 enum dma_data_direction dir,
43 unsigned long attrs)
44{
45 int i;
46 struct scatterlist *sg;
47
48 for_each_sg(sgl, sg, nents, i) {
49 dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset);
50 void *va;
51
52 BUG_ON(!sg_page(sg));
53 va = sg_virt(sg);
54 sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset;
55 sg_dma_len(sg) = sg->length;
56 }
57
58 return nents;
59}
60
61const struct dma_map_ops dma_noop_ops = {
62 .alloc = dma_noop_alloc,
63 .free = dma_noop_free,
64 .map_page = dma_noop_map_page,
65 .map_sg = dma_noop_map_sg,
66};
67
68EXPORT_SYMBOL(dma_noop_ops);