Index: sys/dev/ofw/ofw_bus_subr.h
===================================================================
--- sys/dev/ofw/ofw_bus_subr.h
+++ sys/dev/ofw/ofw_bus_subr.h
@@ -92,8 +92,9 @@
 int	ofw_bus_search_intrmap(void *, int, void *, int, void *, int, void *,
 	    void *, void *, int, phandle_t *);
 
-/* Routines for processing msi maps */
+/* Routines for processing msi and iommu maps. */
 int ofw_bus_msimap(phandle_t, uint16_t, phandle_t *, uint32_t *);
+int ofw_bus_iommu_map(phandle_t, uint16_t, phandle_t *, uint32_t *);
 
 /* Routines for parsing device-tree data into resource lists. */
 int ofw_bus_reg_to_rl(device_t, phandle_t, pcell_t, pcell_t,
Index: sys/dev/ofw/ofw_bus_subr.c
===================================================================
--- sys/dev/ofw/ofw_bus_subr.c
+++ sys/dev/ofw/ofw_bus_subr.c
@@ -491,6 +491,50 @@
 	return (err);
 }
 
+int
+ofw_bus_iommu_map(phandle_t node, uint16_t pci_rid, phandle_t *iommu_parent,
+    uint32_t *iommu_rid)
+{
+	pcell_t mask, iommu_base, rid_base, rid_length;
+	uint32_t masked_rid;
+	pcell_t map[4];
+	ssize_t len;
+	int err, i;
+
+	len = OF_getproplen(node, "iommu-map");
+	if (len <= 0)
+		return (ENOENT);
+        if (len > sizeof(map))
+                return (ENOMEM);
+
+	len = OF_getencprop(node, "iommu-map", map, 16);
+
+	err = ENOENT;
+	mask = 0xffffffff;
+	OF_getencprop(node, "iommu-map-mask", &mask, sizeof(mask));
+
+	masked_rid = pci_rid & mask;
+	for (i = 0; i < len; i += 4) {
+		rid_base = map[i + 0];
+		rid_length = map[i + 3];
+
+		if (masked_rid < rid_base ||
+		    masked_rid >= (rid_base + rid_length))
+			continue;
+
+		iommu_base = map[i + 2];
+
+		if (iommu_parent != NULL)
+			*iommu_parent = map[i + 1];
+		if (iommu_rid != NULL)
+			*iommu_rid = masked_rid - rid_base + iommu_base;
+		err = 0;
+		break;
+	}
+
+	return (err);
+}
+
 static int
 ofw_bus_reg_to_rl_helper(device_t dev, phandle_t node, pcell_t acells, pcell_t scells,
     struct resource_list *rl, const char *reg_source)
Index: sys/dev/pci/pci.c
===================================================================
--- sys/dev/pci/pci.c
+++ sys/dev/pci/pci.c
@@ -138,6 +138,8 @@
 
 static int		pci_get_id_method(device_t dev, device_t child,
 			    enum pci_id_type type, uintptr_t *rid);
+static int		pci_get_iommu_method(device_t dev, device_t child,
+			    uint32_t *id, uint32_t *xref);
 static struct pci_devinfo * pci_fill_devinfo(device_t pcib, device_t bus, int d,
     int b, int s, int f, uint16_t vid, uint16_t did);
 
@@ -213,6 +215,7 @@
 	DEVMETHOD(pci_msix_pba_bar,	pci_msix_pba_bar_method),
 	DEVMETHOD(pci_msix_table_bar,	pci_msix_table_bar_method),
 	DEVMETHOD(pci_get_id,		pci_get_id_method),
+	DEVMETHOD(pci_get_iommu,	pci_get_iommu_method),
 	DEVMETHOD(pci_alloc_devinfo,	pci_alloc_devinfo_method),
 	DEVMETHOD(pci_child_added,	pci_child_added_method),
 #ifdef PCI_IOV
@@ -6327,6 +6330,13 @@
 	return (PCIB_GET_ID(device_get_parent(dev), child, type, id));
 }
 
+static int
+pci_get_iommu_method(device_t dev, device_t child, uint32_t *id, uint32_t *xref)
+{
+
+	return (PCIB_GET_IOMMU(device_get_parent(dev), child, id, xref));
+}
+
 /* Find the upstream port of a given PCI device in a root complex. */
 device_t
 pci_find_pcie_root_port(device_t dev)
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 +373,28 @@
 #endif
 }
 
+static int
+generic_pcie_get_iommu(device_t pci, device_t child, uint32_t *id,
+    uint32_t *xref)
+{
+	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);
+
+	err = ofw_bus_iommu_map(node, pci_rid, &iommu_xref, &iommu_rid);
+	if (err == 0) {
+		*id = iommu_rid;
+		*xref = iommu_xref;
+	}
+
+	return (err);
+}
+
 int
 generic_pcie_get_id(device_t pci, device_t child, enum pci_id_type type,
     uintptr_t *id)
@@ -466,6 +488,7 @@
 	DEVMETHOD(pcib_release_msix,	generic_pcie_fdt_release_msix),
 	DEVMETHOD(pcib_map_msi,		generic_pcie_fdt_map_msi),
 	DEVMETHOD(pcib_get_id,		generic_pcie_get_id),
+	DEVMETHOD(pcib_get_iommu,	generic_pcie_get_iommu),
 	DEVMETHOD(pcib_request_feature,	pcib_request_feature_allow),
 
 	DEVMETHOD(ofw_bus_get_devinfo,	generic_pcie_ofw_get_devinfo),
Index: sys/dev/pci/pci_if.m
===================================================================
--- sys/dev/pci/pci_if.m
+++ sys/dev/pci/pci_if.m
@@ -250,6 +250,13 @@
 	uintptr_t	*id;
 };
 
+METHOD int get_iommu {
+	device_t	dev;
+	device_t	child;
+	uint32_t	*id;
+	uint32_t	*xref;
+};
+
 METHOD struct pci_devinfo * alloc_devinfo {
 	device_t	dev;
 };
Index: sys/dev/pci/pcib_if.m
===================================================================
--- sys/dev/pci/pcib_if.m
+++ sys/dev/pci/pcib_if.m
@@ -186,6 +186,16 @@
 	uintptr_t	*id;
 } DEFAULT pcib_get_id;
 
+#
+# Return the IOMMU Identifier and IOMMU Reference for the device.
+#
+METHOD int get_iommu {
+	device_t	pcib;
+	device_t	dev;
+	uint32_t	*id;
+	uint32_t	*xref;
+} DEFAULT pcib_get_iommu;
+
 #
 # Enable Alternative RID Interpretation if both the downstream port (pcib)
 # and the endpoint device (dev) both support it.
Index: sys/dev/pci/pcib_private.h
===================================================================
--- sys/dev/pci/pcib_private.h
+++ sys/dev/pci/pcib_private.h
@@ -197,6 +197,7 @@
 int		pcib_map_msi(device_t pcib, device_t dev, int irq, uint64_t *addr, uint32_t *data);
 int		pcib_get_id(device_t pcib, device_t dev, enum pci_id_type type,
 		    uintptr_t *id);
+int		pcib_get_iommu(device_t pcib, device_t dev, uint32_t *id, uint32_t *xref);
 void		pcib_decode_rid(device_t pcib, uint16_t rid, int *bus, 
 		    int *slot, int *func);
 int		pcib_request_feature(device_t dev, enum pci_feature feature);
Index: sys/dev/pci/pcib_support.c
===================================================================
--- sys/dev/pci/pcib_support.c
+++ sys/dev/pci/pcib_support.c
@@ -70,6 +70,13 @@
 	return (0);
 }
 
+int
+pcib_get_iommu(device_t pcib, device_t dev, uint32_t *id, uint32_t *xref)
+{
+
+	return (PCI_GET_IOMMU(device_get_parent(pcib), dev, id, xref));
+}
+
 void
 pcib_decode_rid(device_t pcib, uint16_t rid, int *bus, int *slot,
     int *func)
Index: sys/dev/pci/pcivar.h
===================================================================
--- sys/dev/pci/pcivar.h
+++ sys/dev/pci/pcivar.h
@@ -639,6 +639,12 @@
     return (PCI_GET_ID(device_get_parent(dev), dev, type, id));
 }
 
+static __inline int
+pci_get_iommu(device_t dev, uint32_t *id, uint32_t *xref)
+{
+    return (PCI_GET_IOMMU(device_get_parent(dev), dev, id, xref));
+}
+
 /*
  * This is the deprecated interface, there is no way to tell the difference
  * between a failure and a valid value that happens to be the same as the