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/init.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 #include <asm/xen/swiotlb-xen.h>
  14 #include <asm/iommu_table.h>
  15 int swiotlb __read_mostly;
  16
  17 void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
  18                                         dma_addr_t *dma_handle, gfp_t flags,
  19                                         struct dma_attrs *attrs)
  20 {
  21         void *vaddr;
  22
  23         /*
  24          * Don't print a warning when the first allocation attempt fails.
  25          * swiotlb_alloc_coherent() will print a warning when the DMA
  26          * memory allocation ultimately failed.
  27          */
  28         flags |= __GFP_NOWARN;
  29
  30         vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags,
  31                                            attrs);
  32         if (vaddr)
  33                 return vaddr;
  34
  35         return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
  36 }
  37
  38 void x86_swiotlb_free_coherent(struct device *dev, size_t size,
  39                                       void *vaddr, dma_addr_t dma_addr,
  40                                       struct dma_attrs *attrs)
  41 {
  42         if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
  43                 swiotlb_free_coherent(dev, size, vaddr, dma_addr);
  44         else
  45                 dma_generic_free_coherent(dev, size, vaddr, dma_addr, attrs);
  46 }
  47
  48 static struct dma_map_ops swiotlb_dma_ops = {
  49         .mapping_error = swiotlb_dma_mapping_error,
  50         .alloc = x86_swiotlb_alloc_coherent,
  51         .free = x86_swiotlb_free_coherent,
  52         .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
  53         .sync_single_for_device = swiotlb_sync_single_for_device,
  54         .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
  55         .sync_sg_for_device = swiotlb_sync_sg_for_device,
  56         .map_sg = swiotlb_map_sg_attrs,
  57         .unmap_sg = swiotlb_unmap_sg_attrs,
  58         .map_page = swiotlb_map_page,
  59         .unmap_page = swiotlb_unmap_page,
  60         .dma_supported = NULL,
  61 };
  62
  63 /*
  64  * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
  65  *
  66  * This returns non-zero if we are forced to use swiotlb (by the boot
  67  * option).
  68  */
  69 int __init pci_swiotlb_detect_override(void)
  70 {
  71         int use_swiotlb = swiotlb | swiotlb_force;
  72
  73         if (swiotlb_force)
  74                 swiotlb = 1;
  75
  76         return use_swiotlb;
  77 }
  78 IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
  79                   pci_xen_swiotlb_detect,
  80                   pci_swiotlb_init,
  81                   pci_swiotlb_late_init);
  82
  83 /*
  84  * if 4GB or more detected (and iommu=off not set) return 1
  85  * and set swiotlb to 1.
  86  */
  87 int __init pci_swiotlb_detect_4gb(void)
  88 {
  89         /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  90 #ifdef CONFIG_X86_64
  91         if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
  92                 swiotlb = 1;
  93 #endif
  94         return swiotlb;
  95 }
  96 IOMMU_INIT(pci_swiotlb_detect_4gb,
  97            pci_swiotlb_detect_override,
  98            pci_swiotlb_init,
  99            pci_swiotlb_late_init);
 100
 101 void __init pci_swiotlb_init(void)
 102 {
 103         if (swiotlb) {
 104                 swiotlb_init(0);
 105                 dma_ops = &swiotlb_dma_ops;
 106         }
 107 }
 108
 109 void __init pci_swiotlb_late_init(void)
 110 {
 111         /* An IOMMU turned us off. */
 112         if (!swiotlb)
 113                 swiotlb_free();
 114         else {
 115                 printk(KERN_INFO "PCI-DMA: "
 116                        "Using software bounce buffering for IO (SWIOTLB)\n");
 117                 swiotlb_print_info();
 118         }
 119 }