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 /* Nothing is really needed here */ 20 static const struct iommu_ops grant_dma_iommu_ops; 21 22 static const struct of_device_id grant_dma_iommu_of_match[] = { 23 { .compatible = "xen,grant-dma" }, 24 { }, 25 }; 26 27 static int grant_dma_iommu_probe(struct platform_device *pdev) 28 { 29 struct grant_dma_iommu_device *mmu; 30 int ret; 31 32 mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL); 33 if (!mmu) 34 return -ENOMEM; 35 36 mmu->dev = &pdev->dev; 37 38 ret = iommu_device_register(&mmu->iommu, &grant_dma_iommu_ops, &pdev->dev); 39 if (ret) 40 return ret; 41 42 platform_set_drvdata(pdev, mmu); 43 44 return 0; 45 } 46 47 static int grant_dma_iommu_remove(struct platform_device *pdev) 48 { 49 struct grant_dma_iommu_device *mmu = platform_get_drvdata(pdev); 50 51 platform_set_drvdata(pdev, NULL); 52 iommu_device_unregister(&mmu->iommu); 53 54 return 0; 55 } 56 57 static struct platform_driver grant_dma_iommu_driver = { 58 .driver = { 59 .name = "grant-dma-iommu", 60 .of_match_table = grant_dma_iommu_of_match, 61 }, 62 .probe = grant_dma_iommu_probe, 63 .remove = grant_dma_iommu_remove, 64 }; 65 66 static int __init grant_dma_iommu_init(void) 67 { 68 struct device_node *iommu_np; 69 70 iommu_np = of_find_matching_node(NULL, grant_dma_iommu_of_match); 71 if (!iommu_np) 72 return 0; 73 74 of_node_put(iommu_np); 75 76 return platform_driver_register(&grant_dma_iommu_driver); 77 } 78 subsys_initcall(grant_dma_iommu_init); 79