Index: sys/arch/arm64/conf/RPIDEV
===================================================================
RCS file: sys/arch/arm64/conf/RPIDEV
diff -N sys/arch/arm64/conf/RPIDEV
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sys/arch/arm64/conf/RPIDEV	13 Jun 2020 18:58:28 -0000
@@ -0,0 +1,11 @@
+#	$OpenBSD: GENERIC.MP,v 1.5 2018/07/01 21:05:07 kettenis Exp $
+
+include "arch/arm64/conf/GENERIC"
+
+option	MULTIPROCESSOR
+#option	MP_LOCKDEBUG
+#option	WITNESS
+
+cpu*		at mainbus?
+bcmtmon*	at fdt? early 1
+
Index: sys/dev/fdt/files.fdt
===================================================================
RCS file: /cvs/src/sys/dev/fdt/files.fdt,v
retrieving revision 1.139
diff -u -p -u -p -r1.139 files.fdt
--- sys/dev/fdt/files.fdt	11 Jun 2020 00:04:28 -0000	1.139
+++ sys/dev/fdt/files.fdt	13 Jun 2020 18:58:28 -0000
@@ -133,6 +133,10 @@ device	bcmtemp
 attach	bcmtemp at fdt
 file	dev/fdt/bcm2835_temp.c		bcmtemp
 
+device	bcmtmon
+attach  bcmtmon at fdt
+file    dev/fdt/bcm2711_temp.c		bcmtmon
+
 attach	bse at fdt with bse_fdt
 file	dev/fdt/if_bse_fdt.c		bse_fdt
 
Index: sys/dev/fdt/bcm2711_temp.c
===================================================================
RCS file: sys/dev/fdt/bcm2711_temp.c
diff -N sys/dev/fdt/bcm2711_temp.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sys/dev/fdt/bcm2711_temp.c	13 Jun 2020 18:58:28 -0000
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2020 Alastair Poole <netstar@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/device.h>
+#include <sys/sensors.h>
+
+#include <machine/bus.h>
+#include <machine/fdt.h>
+
+#include <dev/ofw/openfirm.h>
+#include <dev/ofw/fdt.h>
+
+/* Registers */
+#define  BCMTMON_TSENSSTAT		0x200
+#define  BCMTMON_TSENSSTAT_VALID	(1 << 10)
+#define  BCMTMON_TSENSSTAT_DATA(x)	((x) & 0x3ff)
+
+#define HREAD4(sc, reg)	\
+	(bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
+
+struct bcmtmon_softc {
+	struct device		sc_dev;
+	bus_space_tag_t		sc_iot;
+	bus_space_handle_t	sc_ioh;
+
+	int32_t			sc_slope;
+	int32_t			sc_offset;
+
+	struct ksensor		sc_sensor;
+	struct ksensordev	sc_sensordev;
+};
+
+int	bcmtmon_match(struct device *, void *, void *);
+void	bcmtmon_attach(struct device *, struct device *, void *);
+
+struct cfattach	bcmtmon_ca = {
+	sizeof (struct bcmtmon_softc), bcmtmon_match, bcmtmon_attach
+};
+
+struct cfdriver bcmtmon_cd = {
+	NULL, "bcmtmon", DV_DULL
+};
+
+void	bcmtmon_refresh_sensors(void *);
+
+int
+bcmtmon_match(struct device *parent, void *match, void *aux)
+{
+	struct fdt_attach_args *faa = aux;
+	
+	return OF_is_compatible(faa->fa_node, "brcm,bcm2711-avs-monitor");
+}
+
+void
+bcmtmon_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct bcmtmon_softc *sc = (struct bcmtmon_softc *)self;
+	struct fdt_attach_args *faa = aux;
+	
+	if (faa->fa_nreg < 1) {
+		printf(": no registers\n");
+		return;
+	}
+
+	sc->sc_iot = faa->fa_iot;
+
+	if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
+	    faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
+		printf(": can't map registers\n");
+		return;
+	}
+
+	printf("\n");
+
+	sc->sc_slope = -487;
+	sc->sc_offset = 410040;
+
+	/* Register sensors. */
+	strlcpy(sc->sc_sensordev.xname, sc->sc_dev.dv_xname,
+	    sizeof(sc->sc_sensordev.xname));
+	sc->sc_sensor.type = SENSOR_TEMP;
+	sc->sc_sensor.flags = SENSOR_FINVALID;
+	sensor_attach(&sc->sc_sensordev, &sc->sc_sensor);
+	sensordev_install(&sc->sc_sensordev);
+	sensor_task_register(sc, bcmtmon_refresh_sensors, 5);
+}
+
+void
+bcmtmon_refresh_sensors(void *arg)
+{
+	struct bcmtmon_softc *sc = arg;
+	int32_t code, temp;
+
+	code = HREAD4(sc, BCMTMON_TSENSSTAT);
+	temp = sc->sc_slope * BCMTMON_TSENSSTAT_DATA(code) + sc->sc_offset;
+
+	sc->sc_sensor.value = 273150000 + 1000 * temp;
+
+	if (code & BCMTMON_TSENSSTAT_VALID)
+		sc->sc_sensor.flags &= ~SENSOR_FINVALID;
+	else
+		sc->sc_sensor.flags |= SENSOR_FINVALID;
+}