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// SPDX-License-Identifier: GPL-2.0
#include <linux/pci.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/swiotlb.h>
#include <linux/memblock.h>
#include <linux/dma-direct.h>
#include <linux/cc_platform.h>
#include <asm/iommu.h>
#include <asm/swiotlb.h>
#include <asm/dma.h>
#include <asm/xen/swiotlb-xen.h>
#include <asm/iommu_table.h>
int swiotlb __read_mostly;
/*
* pci_swiotlb_detect_override - set swiotlb to 1 if necessary
*
* This returns non-zero if we are forced to use swiotlb (by the boot
* option).
*/
int __init pci_swiotlb_detect_override(void)
{
if (swiotlb_force == SWIOTLB_FORCE)
swiotlb = 1;
return swiotlb;
}
IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
pci_xen_swiotlb_detect,
pci_swiotlb_init,
pci_swiotlb_late_init);
/*
* If 4GB or more detected (and iommu=off not set) or if SME is active
* then set swiotlb to 1 and return 1.
*/
int __init pci_swiotlb_detect_4gb(void)
{
/* don't initialize swiotlb if iommu=off (no_iommu=1) */
if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
swiotlb = 1;
/*
* Set swiotlb to 1 so that bounce buffers are allocated and used for
* devices that can't support DMA to encrypted memory.
*/
if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
swiotlb = 1;
return swiotlb;
}
IOMMU_INIT(pci_swiotlb_detect_4gb,
pci_swiotlb_detect_override,
pci_swiotlb_init,
pci_swiotlb_late_init);
void __init pci_swiotlb_init(void)
{
if (swiotlb)
swiotlb_init(0);
}
void __init pci_swiotlb_late_init(void)
{
/* An IOMMU turned us off. */
if (!swiotlb)
swiotlb_exit();
else {
printk(KERN_INFO "PCI-DMA: "
"Using software bounce buffering for IO (SWIOTLB)\n");
swiotlb_print_info();
}
}
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