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 void * __init swiotlb_alloc_boot(size_t size, unsigned long nslabs)
  17 {
  18         return alloc_bootmem_low_pages(size);
  19 }
  20
  21 void *swiotlb_alloc(unsigned order, unsigned long nslabs)
  22 {
  23         return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
  24 }
  25
  26 dma_addr_t swiotlb_phys_to_bus(struct device *hwdev, phys_addr_t paddr)
  27 {
  28         return paddr;
  29 }
  30
  31 phys_addr_t swiotlb_bus_to_phys(dma_addr_t baddr)
  32 {
  33         return baddr;
  34 }
  35
  36 int __weak swiotlb_arch_range_needs_mapping(phys_addr_t paddr, size_t size)
  37 {
  38         return 0;
  39 }
  40
  41 static void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
  42                                         dma_addr_t *dma_handle, gfp_t flags)
  43 {
  44         void *vaddr;
  45
  46         vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags);
  47         if (vaddr)
  48                 return vaddr;
  49
  50         return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
  51 }
  52
  53 static struct dma_map_ops swiotlb_dma_ops = {
  54         .mapping_error = swiotlb_dma_mapping_error,
  55         .alloc_coherent = x86_swiotlb_alloc_coherent,
  56         .free_coherent = swiotlb_free_coherent,
  57         .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
  58         .sync_single_for_device = swiotlb_sync_single_for_device,
  59         .sync_single_range_for_cpu = swiotlb_sync_single_range_for_cpu,
  60         .sync_single_range_for_device = swiotlb_sync_single_range_for_device,
  61         .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
  62         .sync_sg_for_device = swiotlb_sync_sg_for_device,
  63         .map_sg = swiotlb_map_sg_attrs,
  64         .unmap_sg = swiotlb_unmap_sg_attrs,
  65         .map_page = swiotlb_map_page,
  66         .unmap_page = swiotlb_unmap_page,
  67         .dma_supported = NULL,
  68 };
  69
  70 void __init pci_swiotlb_init(void)
  71 {
  72         /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  73 #ifdef CONFIG_X86_64
  74         if (!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN)
  75                swiotlb = 1;
  76 #endif
  77         if (swiotlb_force)
  78                 swiotlb = 1;
  79         if (swiotlb) {
  80                 printk(KERN_INFO "PCI-DMA: Using software bounce buffering for IO (SWIOTLB)\n");
  81                 swiotlb_init();
  82                 dma_ops = &swiotlb_dma_ops;
  83         }
  84 }