arch/x86/kernel/pci-swiotlb.c

   1 /* Glue code to lib/swiotlb.c */
   2
   3 #include <linux/pci.h>
   4 #include <linux/cache.h>
   5 #include <linux/module.h>
   6 #include <linux/swiotlb.h>
   7 #include <linux/bootmem.h>
   8 #include <linux/dma-mapping.h>
   9
  10 #include <asm/iommu.h>
  11 #include <asm/swiotlb.h>
  12 #include <asm/dma.h>
  13
  14 int swiotlb __read_mostly;
  15
  16 static void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
  17                                         dma_addr_t *dma_handle, gfp_t flags)
  18 {
  19         void *vaddr;
  20
  21         vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags);
  22         if (vaddr)
  23                 return vaddr;
  24
  25         return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
  26 }
  27
  28 static struct dma_map_ops swiotlb_dma_ops = {
  29         .mapping_error = swiotlb_dma_mapping_error,
  30         .alloc_coherent = x86_swiotlb_alloc_coherent,
  31         .free_coherent = swiotlb_free_coherent,
  32         .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
  33         .sync_single_for_device = swiotlb_sync_single_for_device,
  34         .sync_single_range_for_cpu = swiotlb_sync_single_range_for_cpu,
  35         .sync_single_range_for_device = swiotlb_sync_single_range_for_device,
  36         .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
  37         .sync_sg_for_device = swiotlb_sync_sg_for_device,
  38         .map_sg = swiotlb_map_sg_attrs,
  39         .unmap_sg = swiotlb_unmap_sg_attrs,
  40         .map_page = swiotlb_map_page,
  41         .unmap_page = swiotlb_unmap_page,
  42         .dma_supported = NULL,
  43 };
  44
  45 /*
  46  * pci_swiotlb_init - initialize swiotlb if necessary
  47  *
  48  * This returns non-zero if we are forced to use swiotlb (by the boot
  49  * option).
  50  */
  51 int __init pci_swiotlb_init(void)
  52 {
  53         int use_swiotlb = swiotlb | swiotlb_force;
  54
  55         /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  56 #ifdef CONFIG_X86_64
  57         if (!no_iommu && max_pfn > MAX_DMA32_PFN)
  58                 swiotlb = 1;
  59 #endif
  60         if (swiotlb_force)
  61                 swiotlb = 1;
  62
  63         if (swiotlb) {
  64                 swiotlb_init(0);
  65                 dma_ops = &swiotlb_dma_ops;
  66         }
  67
  68         return use_swiotlb;
  69 }