arch/x86/kernel/pci-dma.c

#include <linux/dma-mapping.h>
#include <linux/dmar.h>
#include <linux/bootmem.h>
#include <linux/pci.h>

#include <asm/proto.h>
#include <asm/dma.h>
#include <asm/gart.h>
#include <asm/calgary.h>

int forbid_dac __read_mostly;
EXPORT_SYMBOL(forbid_dac);

const struct dma_mapping_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);

int iommu_sac_force __read_mostly = 0;

#ifdef CONFIG_IOMMU_DEBUG
int panic_on_overflow __read_mostly = 1;
int force_iommu __read_mostly = 1;
#else
int panic_on_overflow __read_mostly = 0;
int force_iommu __read_mostly = 0;
#endif

int dma_set_mask(struct device *dev, u64 mask)
{
	if (!dev->dma_mask || !dma_supported(dev, mask))
		return -EIO;

	*dev->dma_mask = mask;

	return 0;
}
EXPORT_SYMBOL(dma_set_mask);

#ifdef CONFIG_X86_64
static __initdata void *dma32_bootmem_ptr;
static unsigned long dma32_bootmem_size __initdata = (128ULL<<20);

static int __init parse_dma32_size_opt(char *p)
{
	if (!p)
		return -EINVAL;
	dma32_bootmem_size = memparse(p, &p);
	return 0;
}
early_param("dma32_size", parse_dma32_size_opt);

void __init dma32_reserve_bootmem(void)
{
	unsigned long size, align;
	if (end_pfn <= MAX_DMA32_PFN)
		return;

	align = 64ULL<<20;
	size = round_up(dma32_bootmem_size, align);
	dma32_bootmem_ptr = __alloc_bootmem_nopanic(size, align,
				 __pa(MAX_DMA_ADDRESS));
	if (dma32_bootmem_ptr)
		dma32_bootmem_size = size;
	else
		dma32_bootmem_size = 0;
}
static void __init dma32_free_bootmem(void)
{
	int node;

	if (end_pfn <= MAX_DMA32_PFN)
		return;

	if (!dma32_bootmem_ptr)
		return;

	for_each_online_node(node)
		free_bootmem_node(NODE_DATA(node), __pa(dma32_bootmem_ptr),
				  dma32_bootmem_size);

	dma32_bootmem_ptr = NULL;
	dma32_bootmem_size = 0;
}

void __init pci_iommu_alloc(void)
{
	/* free the range so iommu could get some range less than 4G */
	dma32_free_bootmem();
	/*
	 * The order of these functions is important for
	 * fall-back/fail-over reasons
	 */
#ifdef CONFIG_GART_IOMMU
	gart_iommu_hole_init();
#endif

#ifdef CONFIG_CALGARY_IOMMU
	detect_calgary();
#endif

	detect_intel_iommu();

#ifdef CONFIG_SWIOTLB
	pci_swiotlb_init();
#endif
}
#endif

int dma_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_PCI
	if (mask > 0xffffffff && forbid_dac > 0) {
		printk(KERN_INFO "PCI: Disallowing DAC for device %s\n",
				 dev->bus_id);
		return 0;
	}
#endif

	if (dma_ops->dma_supported)
		return dma_ops->dma_supported(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)) {
		printk(KERN_INFO "%s: Force SAC with mask %Lx\n",
				 dev->bus_id, mask);
		return 0;
	}

	return 1;
}
EXPORT_SYMBOL(dma_supported);


static int __init pci_iommu_init(void)
{
#ifdef CONFIG_CALGARY_IOMMU
	calgary_iommu_init();
#endif

	intel_iommu_init();

#ifdef CONFIG_GART_IOMMU
	gart_iommu_init();
#endif

	no_iommu_init();
	return 0;
}

void pci_iommu_shutdown(void)
{
	gart_iommu_shutdown();
}
/* Must execute after PCI subsystem */
fs_initcall(pci_iommu_init);

#ifdef CONFIG_PCI
/* Many VIA bridges seem to corrupt data for DAC. Disable it here */

static __devinit void via_no_dac(struct pci_dev *dev)
{
	if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
		printk(KERN_INFO "PCI: VIA PCI bridge detected."
				 "Disabling DAC.\n");
		forbid_dac = 1;
	}
}
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
#endif