kernel/dma/remap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2014 The Linux Foundation
   4  */
   5 #include <linux/dma-mapping.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         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  */
  22 void *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, size >> PAGE_SHIFT, VM_DMA_COHERENT, prot);
  28         if (vaddr)
  29                 find_vm_area(vaddr)->pages = pages;
  30         return vaddr;
  31 }
  32
  33 /*
  34  * Remaps an allocated contiguous region into another vm_area.
  35  * Cannot be used in non-sleeping contexts
  36  */
  37 void *dma_common_contiguous_remap(struct page *page, size_t size,
  38                         pgprot_t prot, const void *caller)
  39 {
  40         int count = size >> PAGE_SHIFT;
  41         struct page **pages;
  42         void *vaddr;
  43         int i;
  44
  45         pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
  46         if (!pages)
  47                 return NULL;
  48         for (i = 0; i < count; i++)
  49                 pages[i] = nth_page(page, i);
  50         vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
  51         kfree(pages);
  52
  53         return vaddr;
  54 }
  55
  56 /*
  57  * Unmaps a range previously mapped by dma_common_*_remap
  58  */
  59 void dma_common_free_remap(void *cpu_addr, size_t size)
  60 {
  61         struct vm_struct *area = find_vm_area(cpu_addr);
  62
  63         if (!area || area->flags != VM_DMA_COHERENT) {
  64                 WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
  65                 return;
  66         }
  67
  68         unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
  69         vunmap(cpu_addr);
  70 }