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-rw-r--r--drivers/xen/grant-dma-iommu.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/drivers/xen/grant-dma-iommu.c b/drivers/xen/grant-dma-iommu.c
new file mode 100644
index 000000000..6a9fe02c6
--- /dev/null
+++ b/drivers/xen/grant-dma-iommu.c
@@ -0,0 +1,85 @@
+// 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 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);