1 // SPDX-License-Identifier: GPL-2.0
2 /* Glue code to lib/swiotlb.c */
5 #include <linux/cache.h>
6 #include <linux/init.h>
7 #include <linux/swiotlb.h>
8 #include <linux/bootmem.h>
9 #include <linux/dma-direct.h>
10 #include <linux/mem_encrypt.h>
12 #include <asm/iommu.h>
13 #include <asm/swiotlb.h>
15 #include <asm/xen/swiotlb-xen.h>
16 #include <asm/iommu_table.h>
18 int swiotlb __read_mostly
;
21 * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
23 * This returns non-zero if we are forced to use swiotlb (by the boot
26 int __init
pci_swiotlb_detect_override(void)
28 if (swiotlb_force
== SWIOTLB_FORCE
)
33 IOMMU_INIT_FINISH(pci_swiotlb_detect_override
,
34 pci_xen_swiotlb_detect
,
36 pci_swiotlb_late_init
);
39 * If 4GB or more detected (and iommu=off not set) or if SME is active
40 * then set swiotlb to 1 and return 1.
42 int __init
pci_swiotlb_detect_4gb(void)
44 /* don't initialize swiotlb if iommu=off (no_iommu=1) */
45 if (!no_iommu
&& max_possible_pfn
> MAX_DMA32_PFN
)
49 * If SME is active then swiotlb will be set to 1 so that bounce
50 * buffers are allocated and used for devices that do not support
51 * the addressing range required for the encryption mask.
58 IOMMU_INIT(pci_swiotlb_detect_4gb
,
59 pci_swiotlb_detect_override
,
61 pci_swiotlb_late_init
);
63 void __init
pci_swiotlb_init(void)
67 dma_ops
= &swiotlb_dma_ops
;
71 void __init
pci_swiotlb_late_init(void)
73 /* An IOMMU turned us off. */
77 printk(KERN_INFO
"PCI-DMA: "
78 "Using software bounce buffering for IO (SWIOTLB)\n");