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// 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;
};
static struct iommu_device *grant_dma_iommu_probe_device(struct device *dev)
{
return ERR_PTR(-ENODEV);
}
/* Nothing is really needed here except a dummy probe_device callback */
static const struct iommu_ops grant_dma_iommu_ops = {
.probe_device = grant_dma_iommu_probe_device,
};
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 void 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);
}
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);
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