1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2014 The Linux Foundation
4 */
5#include <linux/dma-map-ops.h>
6#include <linux/slab.h>
7#include <linux/vmalloc.h>
8
9struct page **dma_common_find_pages(void *cpu_addr)
10{
11 struct vm_struct *area = find_vm_area(addr: cpu_addr);
12
13 if (!area || area->flags != VM_DMA_COHERENT)
14 return NULL;
15 return area->pages;
16}
17
18/*
19 * Remaps an array of PAGE_SIZE pages into another vm_area.
20 * Cannot be used in non-sleeping contexts
21 */
22void *dma_common_pages_remap(struct page **pages, size_t size,
23 pgprot_t prot, const void *caller)
24{
25 void *vaddr;
26
27 vaddr = vmap(pages, PAGE_ALIGN(size) >> PAGE_SHIFT,
28 VM_DMA_COHERENT, prot);
29 if (vaddr)
30 find_vm_area(addr: vaddr)->pages = pages;
31 return vaddr;
32}
33
34/*
35 * Remaps an allocated contiguous region into another vm_area.
36 * Cannot be used in non-sleeping contexts
37 */
38void *dma_common_contiguous_remap(struct page *page, size_t size,
39 pgprot_t prot, const void *caller)
40{
41 int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
42 struct page **pages;
43 void *vaddr;
44 int i;
45
46 pages = kvmalloc_array(n: count, size: sizeof(struct page *), GFP_KERNEL);
47 if (!pages)
48 return NULL;
49 for (i = 0; i < count; i++)
50 pages[i] = nth_page(page, i);
51 vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
52 kvfree(addr: pages);
53
54 return vaddr;
55}
56
57/*
58 * Unmaps a range previously mapped by dma_common_*_remap
59 */
60void dma_common_free_remap(void *cpu_addr, size_t size)
61{
62 struct vm_struct *area = find_vm_area(addr: cpu_addr);
63
64 if (!area || area->flags != VM_DMA_COHERENT) {
65 WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
66 return;
67 }
68
69 vunmap(addr: cpu_addr);
70}
71

source code of linux/kernel/dma/remap.c