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pci-dma.c

/*
 * Dynamic DMA mapping support.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/dmar.h>
#include <asm/iommu.h>
#include <asm/machvec.h>
#include <linux/dma-mapping.h>

#include <asm/system.h>

#ifdef CONFIG_DMAR

#include <linux/kernel.h>

#include <asm/page.h>

dma_addr_t bad_dma_address __read_mostly;
EXPORT_SYMBOL(bad_dma_address);

static int iommu_sac_force __read_mostly;

int no_iommu __read_mostly;
#ifdef CONFIG_IOMMU_DEBUG
int force_iommu __read_mostly = 1;
#else
int force_iommu __read_mostly;
#endif

/* Set this to 1 if there is a HW IOMMU in the system */
int iommu_detected __read_mostly;

/* Dummy device used for NULL arguments (normally ISA). Better would
   be probably a smaller DMA mask, but this is bug-to-bug compatible
   to i386. */
struct device fallback_dev = {
      .bus_id = "fallback device",
      .coherent_dma_mask = DMA_32BIT_MASK,
      .dma_mask = &fallback_dev.coherent_dma_mask,
};

void __init pci_iommu_alloc(void)
{
      /*
       * The order of these functions is important for
       * fall-back/fail-over reasons
       */
      detect_intel_iommu();

#ifdef CONFIG_SWIOTLB
      pci_swiotlb_init();
#endif
}

static int __init pci_iommu_init(void)
{
      if (iommu_detected)
            intel_iommu_init();

      return 0;
}

/* Must execute after PCI subsystem */
fs_initcall(pci_iommu_init);

void pci_iommu_shutdown(void)
{
      return;
}

void __init
iommu_dma_init(void)
{
      return;
}

struct dma_mapping_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);

int iommu_dma_supported(struct device *dev, u64 mask)
{
      struct dma_mapping_ops *ops = get_dma_ops(dev);

      if (ops->dma_supported_op)
            return ops->dma_supported_op(dev, mask);

      /* Copied from i386. Doesn't make much sense, because it will
         only work for pci_alloc_coherent.
         The caller just has to use GFP_DMA in this case. */
      if (mask < DMA_24BIT_MASK)
            return 0;

      /* Tell the device to use SAC when IOMMU force is on.  This
         allows the driver to use cheaper accesses in some cases.

         Problem with this is that if we overflow the IOMMU area and
         return DAC as fallback address the device may not handle it
         correctly.

         As a special case some controllers have a 39bit address
         mode that is as efficient as 32bit (aic79xx). Don't force
         SAC for these.  Assume all masks <= 40 bits are of this
         type. Normally this doesn't make any difference, but gives
         more gentle handling of IOMMU overflow. */
      if (iommu_sac_force && (mask >= DMA_40BIT_MASK)) {
            dev_info(dev, "Force SAC with mask %lx\n", mask);
            return 0;
      }

      return 1;
}
EXPORT_SYMBOL(iommu_dma_supported);

#endif

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