1. 根目录:
2. arch
3. ia64
4. kernel
5. 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>


#ifdef CONFIG_INTEL_IOMMU

#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

int iommu_pass_through;

extern struct dma_map_ops intel_dma_ops;

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;
}

int iommu_dma_supported(struct device *dev, u64 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_BIT_MASK(24))
		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_BIT_MASK(40))) {
		dev_info(dev, "Force SAC with mask %llx\n", mask);
		return 0;
	}

	return 1;
}
EXPORT_SYMBOL(iommu_dma_supported);

void __init pci_iommu_alloc(void)
{
	dma_ops = &intel_dma_ops;

	dma_ops->sync_single_for_cpu = machvec_dma_sync_single;
	dma_ops->sync_sg_for_cpu = machvec_dma_sync_sg;
	dma_ops->sync_single_for_device = machvec_dma_sync_single;
	dma_ops->sync_sg_for_device = machvec_dma_sync_sg;
	dma_ops->dma_supported = iommu_dma_supported;

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

#ifdef CONFIG_SWIOTLB
	pci_swiotlb_init();
#endif
}

#endif