// SPDX-License-Identifier: GPL-2.0 /* * Stub IOMMU driver which does nothing. * The main purpose of it being present is to reuse generic IOMMU device tree * bindings by Xen grant DMA-mapping layer. * * Copyright (C) 2022 EPAM Systems Inc. */ #include <linux/iommu.h> #include <linux/of.h> #include <linux/platform_device.h> struct grant_dma_iommu_device { struct device *dev; struct iommu_device iommu; }; /* Nothing is really needed here */ static const struct iommu_ops grant_dma_iommu_ops; static const struct of_device_id grant_dma_iommu_of_match[] = { { .compatible = "xen,grant-dma" }, { }, }; static int grant_dma_iommu_probe(struct platform_device *pdev) { struct grant_dma_iommu_device *mmu; int ret; mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL); if (!mmu) return -ENOMEM; mmu->dev = &pdev->dev; ret = iommu_device_register(&mmu->iommu, &grant_dma_iommu_ops, &pdev->dev); if (ret) return ret; platform_set_drvdata(pdev, mmu); return 0; } static int grant_dma_iommu_remove(struct platform_device *pdev) { struct grant_dma_iommu_device *mmu = platform_get_drvdata(pdev); platform_set_drvdata(pdev, NULL); iommu_device_unregister(&mmu->iommu); return 0; } static struct platform_driver grant_dma_iommu_driver = { .driver = { .name = "grant-dma-iommu", .of_match_table = grant_dma_iommu_of_match, }, .probe = grant_dma_iommu_probe, .remove = grant_dma_iommu_remove, }; static int __init grant_dma_iommu_init(void) { struct device_node *iommu_np; iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match); if (!iommu_np) return 0; of_node_put(iommu_np); return platform_driver_register(&grant_dma_iommu_driver); } subsys_initcall(grant_dma_iommu_init);