kernel/dma/remap.c

   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
   9 struct page **dma_common_find_pages(void *cpu_addr)
  10 {
  11         struct vm_struct *area = find_vm_area(cpu_addr);
  12
  13         if (!area || !(area->flags & VM_DMA_COHERENT))
  14                 return NULL;
  15         WARN(area->flags != VM_DMA_COHERENT,
  16              "unexpected flags in area: %p\n", cpu_addr);
  17         return area->pages;
  18 }
  19
  20 /*
  21  * Remaps an array of PAGE_SIZE pages into another vm_area.
  22  * Cannot be used in non-sleeping contexts
  23  */
  24 void *dma_common_pages_remap(struct page **pages, size_t size,
  25                          pgprot_t prot, const void *caller)
  26 {
  27         void *vaddr;
  28
  29         vaddr = vmap(pages, PAGE_ALIGN(size) >> PAGE_SHIFT,
  30                      VM_DMA_COHERENT, prot);
  31         if (vaddr)
  32                 find_vm_area(vaddr)->pages = pages;
  33         return vaddr;
  34 }
  35
  36 /*
  37  * Remaps an allocated contiguous region into another vm_area.
  38  * Cannot be used in non-sleeping contexts
  39  */
  40 void *dma_common_contiguous_remap(struct page *page, size_t size,
  41                         pgprot_t prot, const void *caller)
  42 {
  43         int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
  44         struct page **pages;
  45         void *vaddr;
  46         int i;
  47
  48         pages = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
  49         if (!pages)
  50                 return NULL;
  51         for (i = 0; i < count; i++)
  52                 pages[i] = nth_page(page, i);
  53         vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
  54         kvfree(pages);
  55
  56         return vaddr;
  57 }
  58
  59 /*
  60  * Unmaps a range previously mapped by dma_common_*_remap
  61  */
  62 void dma_common_free_remap(void *cpu_addr, size_t size)
  63 {
  64         struct vm_struct *area = find_vm_area(cpu_addr);
  65
  66         if (!area || !(area->flags & VM_DMA_COHERENT)) {
  67                 WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
  68                 return;
  69         }
  70
  71         vunmap(cpu_addr);
  72 }