Index: sys/dev/fdt/simplebus.h
===================================================================
--- sys/dev/fdt/simplebus.h
+++ sys/dev/fdt/simplebus.h
@@ -49,6 +49,8 @@
 	int nranges;
 
 	pcell_t acells, scells;
+
+	bus_dma_tag_t dmat;
 };
 
 struct simplebus_devinfo {
Index: sys/dev/fdt/simplebus.c
===================================================================
--- sys/dev/fdt/simplebus.c
+++ sys/dev/fdt/simplebus.c
@@ -34,6 +34,7 @@
 #include <sys/kernel.h>
 #include <sys/rman.h>
 
+#include <machine/bus.h>
 #include <dev/ofw/openfirm.h>
 #include <dev/ofw/ofw_bus.h>
 #include <dev/ofw/ofw_bus_subr.h>
@@ -65,6 +66,7 @@
 
 static int simplebus_fill_ranges(phandle_t node,
     struct simplebus_softc *sc);
+static bus_dma_tag_t simplebus_get_dma_tag(device_t, device_t);
 
 /*
  * Driver methods.
@@ -96,6 +98,8 @@
 	DEVMETHOD(bus_child_pnpinfo_str, ofw_bus_gen_child_pnpinfo_str),
 	DEVMETHOD(bus_get_resource_list, simplebus_get_resource_list),
 
+	DEVMETHOD(bus_get_dma_tag,	simplebus_get_dma_tag),
+
 	/* ofw_bus interface */
 	DEVMETHOD(ofw_bus_get_devinfo,	simplebus_get_devinfo),
 	DEVMETHOD(ofw_bus_get_compat,	ofw_bus_gen_get_compat),
@@ -144,6 +148,7 @@
 {
 	struct		simplebus_softc *sc;
 	phandle_t	node;
+	int		flags = 0;
 
 	sc = device_get_softc(dev);
 	simplebus_init(dev, 0);
@@ -152,6 +157,22 @@
 		return (ENXIO);
 	}
 
+	if (ofw_bus_has_prop(dev, "dma-coherent"))
+		flags |= BUS_DMA_COHERENT;
+
+	/* Create the parent DMA tag to pass down the coherent flag */
+	bus_dma_tag_create(bus_get_dma_tag(dev), /* parent */
+	    1, 0,			/* alignment, bounds */
+	    BUS_SPACE_MAXADDR,		/* lowaddr */
+	    BUS_SPACE_MAXADDR,		/* highaddr */
+	    NULL, NULL,			/* filter, filterarg */
+	    BUS_SPACE_MAXSIZE,		/* maxsize */
+	    BUS_SPACE_UNRESTRICTED,	/* nsegments */
+	    BUS_SPACE_MAXSIZE,		/* maxsegsize */
+	    flags,			/* flags */
+	    NULL, NULL,			/* lockfunc, lockarg */
+	    &sc->dmat);
+
 	/*
 	 * In principle, simplebus could have an interrupt map, but ignore that
 	 * for now
@@ -162,6 +183,15 @@
 	return (bus_generic_attach(dev));
 }
 
+static bus_dma_tag_t
+simplebus_get_dma_tag(device_t dev, device_t child)
+{
+	struct simplebus_softc *sc;
+
+	sc = device_get_softc(dev);
+	return (sc->dmat);
+}
+
 void
 simplebus_init(device_t dev, phandle_t node)
 {