Index: sys/dev/pci/pci_host_generic_fdt.c
===================================================================
--- sys/dev/pci/pci_host_generic_fdt.c
+++ sys/dev/pci/pci_host_generic_fdt.c
@@ -373,6 +373,30 @@
 #endif
 }
 
+static int
+generic_pcie_get_iommu(device_t pci, device_t child, uintptr_t *id)
+{
+	struct pci_id_ofw_iommu *iommu;
+	uint32_t iommu_rid;
+	uint32_t iommu_xref;
+	uint16_t pci_rid;
+	phandle_t node;
+	int err;
+
+	node = ofw_bus_get_node(pci);
+	pci_rid = pci_get_rid(child);
+
+	iommu = (struct pci_id_ofw_iommu *)id;
+
+	err = ofw_bus_iommu_map(node, pci_rid, &iommu_xref, &iommu_rid);
+	if (err == 0) {
+		iommu->id = iommu_rid;
+		iommu->xref = iommu_xref;
+	}
+
+	return (err);
+}
+
 int
 generic_pcie_get_id(device_t pci, device_t child, enum pci_id_type type,
     uintptr_t *id)
@@ -382,6 +406,9 @@
 	uint32_t rid;
 	uint16_t pci_rid;
 
+	if (type == PCI_ID_OFW_IOMMU)
+		return (generic_pcie_get_iommu(pci, child, id));
+
 	if (type != PCI_ID_MSI)
 		return (pcib_get_id(pci, child, type, id));
 
Index: sys/dev/pci/pci_if.m
===================================================================
--- sys/dev/pci/pci_if.m
+++ sys/dev/pci/pci_if.m
@@ -59,6 +59,7 @@
 	enum pci_id_type {
 	    PCI_ID_RID,
 	    PCI_ID_MSI,
+	    PCI_ID_OFW_IOMMU,
 	};
 
 	enum pci_feature {
Index: sys/dev/pci/pcib_support.c
===================================================================
--- sys/dev/pci/pcib_support.c
+++ sys/dev/pci/pcib_support.c
@@ -59,6 +59,9 @@
 {
 	uint8_t bus, slot, func;
 
+	if (type == PCI_ID_OFW_IOMMU)
+		return (PCI_GET_ID(device_get_parent(pcib), dev, type, id));
+
 	if (type != PCI_ID_RID)
 		return (ENXIO);
 
Index: sys/dev/pci/pcivar.h
===================================================================
--- sys/dev/pci/pcivar.h
+++ sys/dev/pci/pcivar.h
@@ -127,6 +127,11 @@
     struct resource *msix_pba_res;	/* Resource containing PBA. */
 };
 
+struct pci_id_ofw_iommu {
+	uint32_t id;
+	uint32_t xref;
+};
+
 /* Interesting values for HyperTransport */
 struct pcicfg_ht {
     uint8_t	ht_slave;	/* Non-zero if device is an HT slave. */