Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
pci-dma.c
Go to the documentation of this file.
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 
16 #ifdef CONFIG_INTEL_IOMMU
17 
18 #include <linux/kernel.h>
19 
20 #include <asm/page.h>
21 
24 
25 static int iommu_sac_force __read_mostly;
26 
28 #ifdef CONFIG_IOMMU_DEBUG
30 #else
32 #endif
33 
35 
36 /* Dummy device used for NULL arguments (normally ISA). Better would
37  be probably a smaller DMA mask, but this is bug-to-bug compatible
38  to i386. */
39 struct device fallback_dev = {
40  .init_name = "fallback device",
41  .coherent_dma_mask = DMA_BIT_MASK(32),
42  .dma_mask = &fallback_dev.coherent_dma_mask,
43 };
44 
45 extern struct dma_map_ops intel_dma_ops;
46 
47 static int __init pci_iommu_init(void)
48 {
49  if (iommu_detected)
51 
52  return 0;
53 }
54 
55 /* Must execute after PCI subsystem */
56 fs_initcall(pci_iommu_init);
57 
58 void pci_iommu_shutdown(void)
59 {
60  return;
61 }
62 
63 void __init
64 iommu_dma_init(void)
65 {
66  return;
67 }
68 
69 int iommu_dma_supported(struct device *dev, u64 mask)
70 {
71  /* Copied from i386. Doesn't make much sense, because it will
72  only work for pci_alloc_coherent.
73  The caller just has to use GFP_DMA in this case. */
74  if (mask < DMA_BIT_MASK(24))
75  return 0;
76 
77  /* Tell the device to use SAC when IOMMU force is on. This
78  allows the driver to use cheaper accesses in some cases.
79 
80  Problem with this is that if we overflow the IOMMU area and
81  return DAC as fallback address the device may not handle it
82  correctly.
83 
84  As a special case some controllers have a 39bit address
85  mode that is as efficient as 32bit (aic79xx). Don't force
86  SAC for these. Assume all masks <= 40 bits are of this
87  type. Normally this doesn't make any difference, but gives
88  more gentle handling of IOMMU overflow. */
89  if (iommu_sac_force && (mask >= DMA_BIT_MASK(40))) {
90  dev_info(dev, "Force SAC with mask %llx\n", mask);
91  return 0;
92  }
93 
94  return 1;
95 }
96 EXPORT_SYMBOL(iommu_dma_supported);
97 
98 void __init pci_iommu_alloc(void)
99 {
101 
102  dma_ops->sync_single_for_cpu = machvec_dma_sync_single;
103  dma_ops->sync_sg_for_cpu = machvec_dma_sync_sg;
104  dma_ops->sync_single_for_device = machvec_dma_sync_single;
105  dma_ops->sync_sg_for_device = machvec_dma_sync_sg;
106  dma_ops->dma_supported = iommu_dma_supported;
107 
108  /*
109  * The order of these functions is important for
110  * fall-back/fail-over reasons
111  */
113 
114 #ifdef CONFIG_SWIOTLB
116 #endif
117 }
118 
119 #endif