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83 lines · 1.9 KiB

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
14struct grant_dma_iommu_device {
15 struct device *dev;
16 struct iommu_device iommu;
17};
18
19static 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 */
25static const struct iommu_ops grant_dma_iommu_ops = {
26 .probe_device = grant_dma_iommu_probe_device,
27};
28
29static const struct of_device_id grant_dma_iommu_of_match[] = {
30 { .compatible = "xen,grant-dma" },
31 { },
32};
33
34static 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
54static 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(&mmu->iommu);
60}
61
62static 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 = grant_dma_iommu_remove,
69};
70
71static int __init grant_dma_iommu_init(void)
72{
73 struct device_node *iommu_np;
74
75 iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match);
76 if (!iommu_np)
77 return 0;
78
79 of_node_put(iommu_np);
80
81 return platform_driver_register(&grant_dma_iommu_driver);
82}
83subsys_initcall(grant_dma_iommu_init);