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         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, PAGE_ALIGN(size) >> PAGE_SHIFT,
  28                      VM_DMA_COHERENT, prot);
  29         if (vaddr)
  30                 find_vm_area(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  */
  38 void *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 = kmalloc_array(count, 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         kfree(pages);
  53
  54         return vaddr;
  55 }
  56
  57 /*
  58  * Unmaps a range previously mapped by dma_common_*_remap
  59  */
  60 void dma_common_free_remap(void *cpu_addr, size_t size)
  61 {
  62         struct vm_struct *area = find_vm_area(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         unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
  70         vunmap(cpu_addr);
  71 }