+static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
+{
+ struct of_phandle_args *iommu_spec = data;
+
+ iommu_spec->args[0] = alias;
+ return iommu_spec->np == pdev->bus->dev.of_node;
+}
+
+static const struct iommu_ops
+*of_pci_iommu_configure(struct pci_dev *pdev, struct device_node *bridge_np)
+{
+ const struct iommu_ops *ops;
+ struct of_phandle_args iommu_spec;
+
+ /*
+ * Start by tracing the RID alias down the PCI topology as
+ * far as the host bridge whose OF node we have...
+ * (we're not even attempting to handle multi-alias devices yet)
+ */
+ iommu_spec.args_count = 1;
+ iommu_spec.np = bridge_np;
+ pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
+ /*
+ * ...then find out what that becomes once it escapes the PCI
+ * bus into the system beyond, and which IOMMU it ends up at.
+ */
+ iommu_spec.np = NULL;
+ if (of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
+ "iommu-map-mask", &iommu_spec.np, iommu_spec.args))
+ return NULL;
+
+ ops = of_iommu_get_ops(iommu_spec.np);
+ if (!ops || !ops->of_xlate ||
+ iommu_fwspec_init(&pdev->dev, &iommu_spec.np->fwnode, ops) ||
+ ops->of_xlate(&pdev->dev, &iommu_spec))
+ ops = NULL;
+
+ of_node_put(iommu_spec.np);
+ return ops;
+}
+