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1ca55d50 OT |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Stub IOMMU driver which does nothing. | |
4 | * The main purpose of it being present is to reuse generic IOMMU device tree | |
5 | * bindings by Xen grant DMA-mapping layer. | |
6 | * | |
7 | * Copyright (C) 2022 EPAM Systems Inc. | |
8 | */ | |
9 | ||
10 | #include <linux/iommu.h> | |
11 | #include <linux/of.h> | |
12 | #include <linux/platform_device.h> | |
13 | ||
14 | struct grant_dma_iommu_device { | |
15 | struct device *dev; | |
16 | struct iommu_device iommu; | |
17 | }; | |
18 | ||
2062f9fb OT |
19 | static struct iommu_device *grant_dma_iommu_probe_device(struct device *dev) |
20 | { | |
21 | return ERR_PTR(-ENODEV); | |
22 | } | |
23 | ||
24 | /* Nothing is really needed here except a dummy probe_device callback */ | |
25 | static const struct iommu_ops grant_dma_iommu_ops = { | |
26 | .probe_device = grant_dma_iommu_probe_device, | |
27 | }; | |
1ca55d50 OT |
28 | |
29 | static const struct of_device_id grant_dma_iommu_of_match[] = { | |
30 | { .compatible = "xen,grant-dma" }, | |
31 | { }, | |
32 | }; | |
33 | ||
34 | static int grant_dma_iommu_probe(struct platform_device *pdev) | |
35 | { | |
36 | struct grant_dma_iommu_device *mmu; | |
37 | int ret; | |
38 | ||
39 | mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL); | |
40 | if (!mmu) | |
41 | return -ENOMEM; | |
42 | ||
43 | mmu->dev = &pdev->dev; | |
44 | ||
45 | ret = iommu_device_register(&mmu->iommu, &grant_dma_iommu_ops, &pdev->dev); | |
46 | if (ret) | |
47 | return ret; | |
48 | ||
49 | platform_set_drvdata(pdev, mmu); | |
50 | ||
51 | return 0; | |
52 | } | |
53 | ||
54 | static int grant_dma_iommu_remove(struct platform_device *pdev) | |
55 | { | |
56 | struct grant_dma_iommu_device *mmu = platform_get_drvdata(pdev); | |
57 | ||
58 | platform_set_drvdata(pdev, NULL); | |
59 | iommu_device_unregister(&mmu->iommu); | |
60 | ||
61 | return 0; | |
62 | } | |
63 | ||
64 | static struct platform_driver grant_dma_iommu_driver = { | |
65 | .driver = { | |
66 | .name = "grant-dma-iommu", | |
67 | .of_match_table = grant_dma_iommu_of_match, | |
68 | }, | |
69 | .probe = grant_dma_iommu_probe, | |
70 | .remove = grant_dma_iommu_remove, | |
71 | }; | |
72 | ||
73 | static int __init grant_dma_iommu_init(void) | |
74 | { | |
75 | struct device_node *iommu_np; | |
76 | ||
77 | iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match); | |
78 | if (!iommu_np) | |
79 | return 0; | |
80 | ||
81 | of_node_put(iommu_np); | |
82 | ||
83 | return platform_driver_register(&grant_dma_iommu_driver); | |
84 | } | |
85 | subsys_initcall(grant_dma_iommu_init); |