xref: /openbmc/linux/arch/ia64/kernel/pci-dma.c (revision 4d9b977ca674dd40cfc1409a75cb73fca2cee423)
1 /*
2  * Dynamic DMA mapping support.
3  */
4 
5 #include <linux/types.h>
6 #include <linux/mm.h>
7 #include <linux/string.h>
8 #include <linux/pci.h>
9 #include <linux/module.h>
10 #include <linux/dmar.h>
11 #include <asm/iommu.h>
12 #include <asm/machvec.h>
13 #include <linux/dma-mapping.h>
14 
15 #include <asm/system.h>
16 
17 #ifdef CONFIG_DMAR
18 
19 #include <linux/kernel.h>
20 
21 #include <asm/page.h>
22 
23 dma_addr_t bad_dma_address __read_mostly;
24 EXPORT_SYMBOL(bad_dma_address);
25 
26 static int iommu_sac_force __read_mostly;
27 
28 int no_iommu __read_mostly;
29 #ifdef CONFIG_IOMMU_DEBUG
30 int force_iommu __read_mostly = 1;
31 #else
32 int force_iommu __read_mostly;
33 #endif
34 
35 /* Dummy device used for NULL arguments (normally ISA). Better would
36    be probably a smaller DMA mask, but this is bug-to-bug compatible
37    to i386. */
38 struct device fallback_dev = {
39 	.bus_id = "fallback device",
40 	.coherent_dma_mask = DMA_32BIT_MASK,
41 	.dma_mask = &fallback_dev.coherent_dma_mask,
42 };
43 
44 extern struct dma_mapping_ops vtd_dma_ops;
45 
46 void __init pci_iommu_alloc(void)
47 {
48 	dma_ops = &vtd_dma_ops;
49 	/*
50 	 * The order of these functions is important for
51 	 * fall-back/fail-over reasons
52 	 */
53 	detect_intel_iommu();
54 
55 #ifdef CONFIG_SWIOTLB
56 	pci_swiotlb_init();
57 #endif
58 }
59 
60 static int __init pci_iommu_init(void)
61 {
62 	if (iommu_detected)
63 		intel_iommu_init();
64 
65 	return 0;
66 }
67 
68 /* Must execute after PCI subsystem */
69 fs_initcall(pci_iommu_init);
70 
71 void pci_iommu_shutdown(void)
72 {
73 	return;
74 }
75 
76 void __init
77 iommu_dma_init(void)
78 {
79 	return;
80 }
81 
82 int iommu_dma_supported(struct device *dev, u64 mask)
83 {
84 	struct dma_mapping_ops *ops = get_dma_ops(dev);
85 
86 	if (ops->dma_supported_op)
87 		return ops->dma_supported_op(dev, mask);
88 
89 	/* Copied from i386. Doesn't make much sense, because it will
90 	   only work for pci_alloc_coherent.
91 	   The caller just has to use GFP_DMA in this case. */
92 	if (mask < DMA_24BIT_MASK)
93 		return 0;
94 
95 	/* Tell the device to use SAC when IOMMU force is on.  This
96 	   allows the driver to use cheaper accesses in some cases.
97 
98 	   Problem with this is that if we overflow the IOMMU area and
99 	   return DAC as fallback address the device may not handle it
100 	   correctly.
101 
102 	   As a special case some controllers have a 39bit address
103 	   mode that is as efficient as 32bit (aic79xx). Don't force
104 	   SAC for these.  Assume all masks <= 40 bits are of this
105 	   type. Normally this doesn't make any difference, but gives
106 	   more gentle handling of IOMMU overflow. */
107 	if (iommu_sac_force && (mask >= DMA_40BIT_MASK)) {
108 		dev_info(dev, "Force SAC with mask %lx\n", mask);
109 		return 0;
110 	}
111 
112 	return 1;
113 }
114 EXPORT_SYMBOL(iommu_dma_supported);
115 
116 #endif
117