drivers/xen/grant-dma-iommu.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Stub IOMMU driver which does nothing.
0004  * The main purpose of it being present is to reuse generic IOMMU device tree
0005  * bindings by Xen grant DMA-mapping layer.
0006  *
0007  * Copyright (C) 2022 EPAM Systems Inc.
0008  */
0009
0010 #include <linux/iommu.h>
0011 #include <linux/of.h>
0012 #include <linux/platform_device.h>
0013
0014 struct grant_dma_iommu_device {
0015     struct device *dev;
0016     struct iommu_device iommu;
0017 };
0018
0019 /* Nothing is really needed here */
0020 static const struct iommu_ops grant_dma_iommu_ops;
0021
0022 static const struct of_device_id grant_dma_iommu_of_match[] = {
0023     { .compatible = "xen,grant-dma" },
0024     { },
0025 };
0026
0027 static int grant_dma_iommu_probe(struct platform_device *pdev)
0028 {
0029     struct grant_dma_iommu_device *mmu;
0030     int ret;
0031
0032     mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL);
0033     if (!mmu)
0034         return -ENOMEM;
0035
0036     mmu->dev = &pdev->dev;
0037
0038     ret = iommu_device_register(&mmu->iommu, &grant_dma_iommu_ops, &pdev->dev);
0039     if (ret)
0040         return ret;
0041
0042     platform_set_drvdata(pdev, mmu);
0043
0044     return 0;
0045 }
0046
0047 static int grant_dma_iommu_remove(struct platform_device *pdev)
0048 {
0049     struct grant_dma_iommu_device *mmu = platform_get_drvdata(pdev);
0050
0051     platform_set_drvdata(pdev, NULL);
0052     iommu_device_unregister(&mmu->iommu);
0053
0054     return 0;
0055 }
0056
0057 static struct platform_driver grant_dma_iommu_driver = {
0058     .driver = {
0059         .name = "grant-dma-iommu",
0060         .of_match_table = grant_dma_iommu_of_match,
0061     },
0062     .probe = grant_dma_iommu_probe,
0063     .remove = grant_dma_iommu_remove,
0064 };
0065
0066 static int __init grant_dma_iommu_init(void)
0067 {
0068     struct device_node *iommu_np;
0069
0070     iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match);
0071     if (!iommu_np)
0072         return 0;
0073
0074     of_node_put(iommu_np);
0075
0076     return platform_driver_register(&grant_dma_iommu_driver);
0077 }
0078 subsys_initcall(grant_dma_iommu_init);