release/src-rt-6.x.4708/linux/linux-2.6.36/arch/x86/xen/pci-swiotlb-xen.c

   1 /* Glue code to lib/swiotlb-xen.c */
   2
   3 #include <linux/dma-mapping.h>
   4 #include <xen/swiotlb-xen.h>
   5
   6 #include <asm/xen/hypervisor.h>
   7 #include <xen/xen.h>
   8
   9 int xen_swiotlb __read_mostly;
  10
  11 static struct dma_map_ops xen_swiotlb_dma_ops = {
  12         .mapping_error = xen_swiotlb_dma_mapping_error,
  13         .alloc_coherent = xen_swiotlb_alloc_coherent,
  14         .free_coherent = xen_swiotlb_free_coherent,
  15         .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
  16         .sync_single_for_device = xen_swiotlb_sync_single_for_device,
  17         .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
  18         .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
  19         .map_sg = xen_swiotlb_map_sg_attrs,
  20         .unmap_sg = xen_swiotlb_unmap_sg_attrs,
  21         .map_page = xen_swiotlb_map_page,
  22         .unmap_page = xen_swiotlb_unmap_page,
  23         .dma_supported = xen_swiotlb_dma_supported,
  24 };
  25
  26 /*
  27  * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
  28  *
  29  * This returns non-zero if we are forced to use xen_swiotlb (by the boot
  30  * option).
  31  */
  32 int __init pci_xen_swiotlb_detect(void)
  33 {
  34
  35         /* If running as PV guest, either iommu=soft, or swiotlb=force will
  36          * activate this IOMMU. If running as PV privileged, activate it
  37          * irregardlesss.
  38          */
  39         if ((xen_initial_domain() || swiotlb || swiotlb_force) &&
  40             (xen_pv_domain()))
  41                 xen_swiotlb = 1;
  42
  43         /* If we are running under Xen, we MUST disable the native SWIOTLB.
  44          * Don't worry about swiotlb_force flag activating the native, as
  45          * the 'swiotlb' flag is the only one turning it on. */
  46         if (xen_pv_domain())
  47                 swiotlb = 0;
  48
  49         return xen_swiotlb;
  50 }
  51
  52 void __init pci_xen_swiotlb_init(void)
  53 {
  54         if (xen_swiotlb) {
  55                 xen_swiotlb_init(1);
  56                 dma_ops = &xen_swiotlb_dma_ops;
  57         }
  58 }