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 | |
19 | static struct iommu_device *grant_dma_iommu_probe_device(struct device *dev) |
20 | { |
21 | return ERR_PTR(error: -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 | }; |
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(dev: &pdev->dev, size: sizeof(*mmu), GFP_KERNEL); |
40 | if (!mmu) |
41 | return -ENOMEM; |
42 | |
43 | mmu->dev = &pdev->dev; |
44 | |
45 | ret = iommu_device_register(iommu: &mmu->iommu, ops: &grant_dma_iommu_ops, hwdev: &pdev->dev); |
46 | if (ret) |
47 | return ret; |
48 | |
49 | platform_set_drvdata(pdev, data: mmu); |
50 | |
51 | return 0; |
52 | } |
53 | |
54 | static void 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(iommu: &mmu->iommu); |
60 | } |
61 | |
62 | static struct platform_driver grant_dma_iommu_driver = { |
63 | .driver = { |
64 | .name = "grant-dma-iommu" , |
65 | .of_match_table = grant_dma_iommu_of_match, |
66 | }, |
67 | .probe = grant_dma_iommu_probe, |
68 | .remove_new = grant_dma_iommu_remove, |
69 | }; |
70 | |
71 | static int __init grant_dma_iommu_init(void) |
72 | { |
73 | struct device_node *iommu_np; |
74 | |
75 | iommu_np = of_find_matching_node(NULL, matches: grant_dma_iommu_of_match); |
76 | if (!iommu_np) |
77 | return 0; |
78 | |
79 | of_node_put(node: iommu_np); |
80 | |
81 | return platform_driver_register(&grant_dma_iommu_driver); |
82 | } |
83 | subsys_initcall(grant_dma_iommu_init); |
84 | |