diff --git a/sys/dev/altera/avgen/altera_avgen_nexus.c b/sys/dev/altera/avgen/altera_avgen_nexus.c
new file mode 100644
index 000000000000..a90b54643d9d
--- /dev/null
+++ b/sys/dev/altera/avgen/altera_avgen_nexus.c
@@ -0,0 +1,451 @@
+/*-
+ * Copyright (c) 2012 Robert N. M. Watson
+ * All rights reserved.
+ *
+ * This software was developed by SRI International and the University of
+ * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
+ * ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/bus.h>
+#include <sys/condvar.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/mutex.h>
+#include <sys/rman.h>
+#include <sys/stat.h>
+#include <sys/systm.h>
+#include <sys/uio.h>
+
+#include <machine/bus.h>
+#include <machine/resource.h>
+#include <machine/vm.h>
+
+#include <vm/vm.h>
+
+#include <dev/altera/avgen/altera_avgen.h>
+
+/*
+ * Generic device driver for allowing read(), write(), and mmap() on
+ * memory-mapped, Avalon-attached devices.  There is no actual dependence on
+ * Avalon, so conceivably this should just be soc_dev or similar, since many
+ * system-on-chip bus environments would work fine with the same code.
+ */
+
+static d_mmap_t altera_avgen_mmap;
+static d_read_t altera_avgen_read;
+static d_write_t altera_avgen_write;
+
+static struct cdevsw avg_cdevsw = {
+	.d_version =	D_VERSION,
+	.d_mmap =	altera_avgen_mmap,
+	.d_read =	altera_avgen_read,
+	.d_write =	altera_avgen_write,
+	.d_name =	"altera_avgen",
+};
+
+static int
+altera_avgen_read(struct cdev *dev, struct uio *uio, int flag)
+{
+	struct altera_avgen_softc *sc;
+	u_long offset, size;
+#ifdef NOTYET
+	uint64_t v8;
+#endif
+	uint32_t v4;
+	uint16_t v2;
+	uint8_t v1;
+	u_int width;
+	int error;
+
+	sc = dev->si_drv1;
+	if ((sc->avg_flags & ALTERA_AVALON_FLAG_READ) == 0)
+		return (EACCES);
+	width = sc->avg_width;
+	if (uio->uio_offset < 0 || uio->uio_offset % width != 0 ||
+	    uio->uio_resid % width != 0)
+		return (ENODEV);
+	size = rman_get_size(sc->avg_res);
+	if ((uio->uio_offset + uio->uio_resid < 0) ||
+	    (uio->uio_offset + uio->uio_resid > size))
+		return (ENODEV);
+	while (uio->uio_resid > 0) {
+		offset = uio->uio_offset;
+		if (offset + width > size)
+			return (ENODEV);
+		switch (width) {
+		case 1:
+			v1 = bus_read_1(sc->avg_res, offset);
+			error = uiomove(&v1, sizeof(v1), uio);
+			break;
+			
+		case 2:
+			v2 = bus_read_2(sc->avg_res, offset);
+			error = uiomove(&v2, sizeof(v2), uio);
+			break;
+			
+		case 4:
+			v4 = bus_read_4(sc->avg_res, offset);
+			error = uiomove(&v4, sizeof(v4), uio);
+			break;
+			
+#ifdef NOTYET
+		case 8:
+			v8 = bus_read_8(sc->avg_res, offset);
+			error = uiomove(&v8, sizeof(v8), uio);
+			break;
+			
+#endif
+
+		default:
+			panic("%s: unexpected widthment %u", __func__, width);
+		}
+		if (error)
+			return (error);
+	}
+	return (0);
+}
+
+static int
+altera_avgen_write(struct cdev *dev, struct uio *uio, int flag)
+{
+	struct altera_avgen_softc *sc;
+	u_long offset, size;
+#ifdef NOTYET
+	uint64_t v8;
+#endif
+	uint32_t v4;
+	uint16_t v2;
+	uint8_t v1;
+	u_int width;
+	int error;
+
+	sc = dev->si_drv1;
+	if ((sc->avg_flags & ALTERA_AVALON_FLAG_WRITE) == 0)
+		return (EACCES);
+	width = sc->avg_width;
+	if (uio->uio_offset < 0 || uio->uio_offset % width != 0 ||
+	    uio->uio_resid % width != 0)
+		return (ENODEV);
+	size = rman_get_size(sc->avg_res);
+	while (uio->uio_resid > 0) {
+		offset = uio->uio_offset;
+		if (offset + width > size)
+			return (ENODEV);
+		switch (width) {
+		case 1:
+			error = uiomove(&v1, sizeof(v1), uio);
+			if (error)
+				return (error);
+			bus_write_1(sc->avg_res, offset, v1);
+			break;
+
+		case 2:
+			error = uiomove(&v2, sizeof(v2), uio);
+			if (error)
+				return (error);
+			bus_write_2(sc->avg_res, offset, v2);
+			break;
+
+		case 4:
+			error = uiomove(&v4, sizeof(v4), uio);
+			if (error)
+				return (error);
+			bus_write_4(sc->avg_res, offset, v4);
+			break;
+
+#ifdef NOTYET
+		case 8:
+			error = uiomove(&v8, sizeof(v8), uio);
+			if (error)
+				return (error);
+			bus_write_8(sc->avg_res, offset, v8);
+			break;
+#endif
+
+		default:
+			panic("%s: unexpected width %u", __func__, width);
+		}
+	}
+	return (0);
+}
+
+static int
+altera_avgen_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
+    int nprot, vm_memattr_t *memattr)
+{
+	struct altera_avgen_softc *sc;
+
+	sc = dev->si_drv1;
+	if (nprot & VM_PROT_READ) {
+		if ((sc->avg_flags & ALTERA_AVALON_FLAG_MMAP_READ) == 0)
+			return (EACCES);
+	}
+	if (nprot & VM_PROT_WRITE) {
+		if ((sc->avg_flags & ALTERA_AVALON_FLAG_MMAP_WRITE) == 0)
+			return (EACCES);
+	}
+	if (nprot & VM_PROT_EXECUTE) {
+		if ((sc->avg_flags & ALTERA_AVALON_FLAG_MMAP_EXEC) == 0)
+			return (EACCES);
+	}
+	if (trunc_page(offset) == offset &&
+	    rman_get_size(sc->avg_res) >= offset + PAGE_SIZE) {
+		*paddr = rman_get_start(sc->avg_res) + offset;
+		*memattr = VM_MEMATTR_UNCACHEABLE;
+	} else
+		return (ENODEV);
+	return (0);
+}
+
+static int
+altera_avgen_nexus_probe(device_t dev)
+{
+
+	device_set_desc(dev, "Generic Altera Avalon device attachment");
+	return (BUS_PROBE_DEFAULT);
+}
+
+static int
+altera_avgen_process_options(struct altera_avgen_softc *sc,
+    const char *str_fileio, const char *str_mmapio, const char *str_devname,
+    int devunit)
+{
+	const char *cp;
+	device_t dev = sc->avg_dev;
+
+	/*
+	 * Check for valid combinations of options.
+	 */
+	if (str_fileio == NULL && str_mmapio == NULL) {
+		device_printf(dev,
+		    "at least one of %s or %s must be specified\n",
+		    ALTERA_AVALON_STR_FILEIO, ALTERA_AVALON_STR_MMAPIO);
+		return (ENXIO);
+	}
+	if (str_devname == NULL && devunit != -1) {
+		device_printf(dev, "%s requires %s be specified\n",
+		    ALTERA_AVALON_STR_DEVUNIT, ALTERA_AVALON_STR_DEVNAME);
+		return (ENXIO);
+	}
+
+	/*
+	 * Extract, digest, and save values.
+	 */
+	switch (sc->avg_width) {
+	case 1:
+	case 2:
+	case 4:
+#ifdef NOTYET
+	case 8:
+#endif
+		break;
+
+	default:
+		device_printf(dev, "%s unsupported value %u\n",
+		    ALTERA_AVALON_STR_WIDTH, sc->avg_width);
+		return (ENXIO);
+	}
+	sc->avg_flags = 0;
+	if (str_fileio != NULL) {
+		for (cp = str_fileio; *cp != '\0'; cp++) {
+			switch (*cp) {
+			case ALTERA_AVALON_CHAR_READ:
+				sc->avg_flags |= ALTERA_AVALON_FLAG_READ;
+				break;
+
+			case ALTERA_AVALON_CHAR_WRITE:
+				sc->avg_flags |= ALTERA_AVALON_FLAG_WRITE;
+				break;
+
+			default:
+				device_printf(dev,
+				    "invalid %s character %c\n", 
+				    ALTERA_AVALON_STR_FILEIO, *cp);
+				return (ENXIO);
+			}
+		}
+	}
+	if (str_mmapio != NULL) {
+		for (cp = str_mmapio; *cp != '\0'; cp++) {
+			switch (*cp) {
+			case ALTERA_AVALON_CHAR_READ:
+				sc->avg_flags |= ALTERA_AVALON_FLAG_MMAP_READ;
+				break;
+
+			case ALTERA_AVALON_CHAR_WRITE:
+				sc->avg_flags |=
+				    ALTERA_AVALON_FLAG_MMAP_WRITE;
+				break;
+
+			case ALTERA_AVALON_CHAR_EXEC:
+				sc->avg_flags |= ALTERA_AVALON_FLAG_MMAP_EXEC;
+				break;
+
+			default:
+				device_printf(dev,
+				    "invalid %s character %c\n",
+				    ALTERA_AVALON_STR_MMAPIO, *cp);
+				return (ENXIO);
+			}
+		}
+	}
+	return (0);
+}
+
+static int
+altera_avgen_nexus_attach(device_t dev)
+{
+	struct altera_avgen_softc *sc;
+	const char *str_fileio, *str_mmapio;
+	const char *str_devname;
+	char devname[SPECNAMELEN + 1];
+	int devunit, error;
+
+	sc = device_get_softc(dev);
+	sc->avg_dev = dev;
+	sc->avg_unit = device_get_unit(dev);
+
+	/*
+	 * Query non-standard hints to find out what operations are permitted
+	 * on the device, and whether it is cached.
+	 */
+	str_fileio = NULL;
+	str_mmapio = NULL;
+	str_devname = NULL;
+	devunit = -1;
+	sc->avg_width = 1;
+	error = resource_int_value(device_get_name(dev), device_get_unit(dev),
+	    ALTERA_AVALON_STR_WIDTH, &sc->avg_width);
+	if (error != 0 && error != ENOENT) {
+		device_printf(dev, "invalid %s\n", ALTERA_AVALON_STR_WIDTH);
+		return (error);
+	}
+	(void)resource_string_value(device_get_name(dev),
+	    device_get_unit(dev), ALTERA_AVALON_STR_FILEIO, &str_fileio);
+	(void)resource_string_value(device_get_name(dev),
+	    device_get_unit(dev), ALTERA_AVALON_STR_MMAPIO, &str_mmapio);
+	(void)resource_string_value(device_get_name(dev),
+	    device_get_unit(dev), ALTERA_AVALON_STR_DEVNAME, &str_devname);
+	(void)resource_int_value(device_get_name(dev), device_get_unit(dev),
+	    ALTERA_AVALON_STR_DEVUNIT, &devunit);
+	error = altera_avgen_process_options(sc, str_fileio, str_mmapio,
+	    str_devname, devunit);
+	if (error)
+		return (error);
+
+	/* Select a device name. */
+	if (str_devname != NULL) {
+		if (devunit != -1)
+			(void)snprintf(devname, sizeof(devname), "%s%d",
+			    str_devname, devunit);
+		else
+			(void)snprintf(devname, sizeof(devname), "%s",
+			    str_devname);
+	} else
+		snprintf(devname, sizeof(devname), "%s%d", "avgen",
+		    sc->avg_unit);
+
+	/* Memory allocation and checking. */
+	sc->avg_rid = 0;
+	sc->avg_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY,
+	    &sc->avg_rid, RF_ACTIVE);
+	if (sc->avg_res == NULL) {
+		device_printf(dev, "couldn't map memory\n");
+		return (ENXIO);
+	}
+	if (rman_get_size(sc->avg_res) >= PAGE_SIZE || str_mmapio != NULL) {
+		if (rman_get_size(sc->avg_res) % PAGE_SIZE != 0) {
+			device_printf(dev,
+			    "memory region not even multiple of page size\n");
+			error = ENXIO;
+			goto error;
+		}
+		if (rman_get_start(sc->avg_res) % PAGE_SIZE != 0) {
+			device_printf(dev, "memory region not page-aligned\n");
+			error = ENXIO;
+			goto error;
+		}
+	}
+
+	/* Device node allocation. */
+	if (str_devname == NULL) {
+		str_devname = "altera_avgen%d";
+		devunit = sc->avg_unit;
+	}
+	if (devunit != -1)
+		sc->avg_cdev = make_dev(&avg_cdevsw, sc->avg_unit, UID_ROOT,
+		    GID_WHEEL, S_IRUSR | S_IWUSR, str_devname, devunit);
+	else
+		sc->avg_cdev = make_dev(&avg_cdevsw, sc->avg_unit, UID_ROOT,
+		    GID_WHEEL, S_IRUSR | S_IWUSR, str_devname);
+	if (sc->avg_cdev == NULL) {
+		device_printf(sc->avg_dev, "%s: make_dev failed\n", __func__);
+		error = ENXIO;
+		goto error;
+	}
+	/* XXXRW: Slight race between make_dev(9) and here. */
+	sc->avg_cdev->si_drv1 = sc;
+	return (0);
+
+error:
+	bus_release_resource(dev, SYS_RES_MEMORY, sc->avg_rid, sc->avg_res);
+	return (error);
+}
+
+static int
+altera_avgen_nexus_detach(device_t dev)
+{
+	struct altera_avgen_softc *sc;
+
+	sc = device_get_softc(dev);
+	destroy_dev(sc->avg_cdev);
+	bus_release_resource(dev, SYS_RES_MEMORY, sc->avg_rid, sc->avg_res);
+	return (0);
+}
+
+static device_method_t altera_avgen_nexus_methods[] = {
+	DEVMETHOD(device_probe,		altera_avgen_nexus_probe),
+	DEVMETHOD(device_attach,	altera_avgen_nexus_attach),
+	DEVMETHOD(device_detach,	altera_avgen_nexus_detach),
+	{ 0, 0 }
+};
+
+static driver_t altera_avgen_nexus_driver = {
+	"altera_avgen",
+	altera_avgen_nexus_methods,
+	sizeof(struct altera_avgen_softc),
+};
+
+static devclass_t altera_avgen_devclass;
+
+DRIVER_MODULE(avgen, nexus, altera_avgen_nexus_driver, altera_avgen_devclass,
+    0, 0);