diff --git a/sys/dev/amdsmn/amdsmn.c b/sys/dev/amdsmn/amdsmn.c
index 9a0428608a27..111c3cc8e7c1 100644
--- a/sys/dev/amdsmn/amdsmn.c
+++ b/sys/dev/amdsmn/amdsmn.c
@@ -1,268 +1,275 @@
 /*-
  * Copyright (c) 2017-2020 Conrad Meyer <cem@FreeBSD.org>
  * All rights reserved.
  *
  * 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 ``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 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.
  */
 
 /*
  * Driver for the AMD Family 15h and 17h CPU System Management Network.
  */
 
 #include <sys/param.h>
 #include <sys/bus.h>
 #include <sys/conf.h>
 #include <sys/lock.h>
 #include <sys/kernel.h>
 #include <sys/module.h>
 #include <sys/mutex.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
 
 #include <machine/cpufunc.h>
 #include <machine/cputypes.h>
 #include <machine/md_var.h>
 #include <machine/specialreg.h>
 
 #include <dev/pci/pcivar.h>
 #include <x86/pci_cfgreg.h>
 
 #include <dev/amdsmn/amdsmn.h>
 
 #define	F15H_SMN_ADDR_REG	0xb8
 #define	F15H_SMN_DATA_REG	0xbc
 #define	F17H_SMN_ADDR_REG	0x60
 #define	F17H_SMN_DATA_REG	0x64
 
 #define	PCI_DEVICE_ID_AMD_15H_M60H_ROOT		0x1576
 #define	PCI_DEVICE_ID_AMD_17H_ROOT		0x1450
 #define	PCI_DEVICE_ID_AMD_17H_M10H_ROOT		0x15d0
 #define	PCI_DEVICE_ID_AMD_17H_M30H_ROOT		0x1480	/* Also M70H, F19H M00H/M20H */
 #define	PCI_DEVICE_ID_AMD_17H_M60H_ROOT		0x1630
 #define	PCI_DEVICE_ID_AMD_19H_M10H_ROOT		0x14a4
+#define	PCI_DEVICE_ID_AMD_19H_M40H_ROOT		0x14b5
 #define	PCI_DEVICE_ID_AMD_19H_M60H_ROOT		0x14d8
 #define	PCI_DEVICE_ID_AMD_19H_M70H_ROOT		0x14e8
 
 struct pciid;
 struct amdsmn_softc {
 	struct mtx smn_lock;
 	const struct pciid *smn_pciid;
 };
 
 static const struct pciid {
 	uint16_t	amdsmn_vendorid;
 	uint16_t	amdsmn_deviceid;
 	uint8_t		amdsmn_addr_reg;
 	uint8_t		amdsmn_data_reg;
 } amdsmn_ids[] = {
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_15H_M60H_ROOT,
 		.amdsmn_addr_reg = F15H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F15H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_17H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_17H_M10H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_17H_M30H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_17H_M60H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_19H_M10H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
+	{
+		.amdsmn_vendorid = CPU_VENDOR_AMD,
+		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_19H_M40H_ROOT,
+		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
+		.amdsmn_data_reg = F17H_SMN_DATA_REG,
+	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_19H_M60H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 	{
 		.amdsmn_vendorid = CPU_VENDOR_AMD,
 		.amdsmn_deviceid = PCI_DEVICE_ID_AMD_19H_M70H_ROOT,
 		.amdsmn_addr_reg = F17H_SMN_ADDR_REG,
 		.amdsmn_data_reg = F17H_SMN_DATA_REG,
 	},
 };
 
 /*
  * Device methods.
  */
 static void 	amdsmn_identify(driver_t *driver, device_t parent);
 static int	amdsmn_probe(device_t dev);
 static int	amdsmn_attach(device_t dev);
 static int	amdsmn_detach(device_t dev);
 
 static device_method_t amdsmn_methods[] = {
 	/* Device interface */
 	DEVMETHOD(device_identify,	amdsmn_identify),
 	DEVMETHOD(device_probe,		amdsmn_probe),
 	DEVMETHOD(device_attach,	amdsmn_attach),
 	DEVMETHOD(device_detach,	amdsmn_detach),
 	DEVMETHOD_END
 };
 
 static driver_t amdsmn_driver = {
 	"amdsmn",
 	amdsmn_methods,
 	sizeof(struct amdsmn_softc),
 };
 
 DRIVER_MODULE(amdsmn, hostb, amdsmn_driver, NULL, NULL);
 MODULE_VERSION(amdsmn, 1);
 MODULE_PNP_INFO("U16:vendor;U16:device", pci, amdsmn, amdsmn_ids,
     nitems(amdsmn_ids));
 
 static bool
 amdsmn_match(device_t parent, const struct pciid **pciid_out)
 {
 	uint16_t vendor, device;
 	size_t i;
 
 	vendor = pci_get_vendor(parent);
 	device = pci_get_device(parent);
 
 	for (i = 0; i < nitems(amdsmn_ids); i++) {
 		if (vendor == amdsmn_ids[i].amdsmn_vendorid &&
 		    device == amdsmn_ids[i].amdsmn_deviceid) {
 			if (pciid_out != NULL)
 				*pciid_out = &amdsmn_ids[i];
 			return (true);
 		}
 	}
 	return (false);
 }
 
 static void
 amdsmn_identify(driver_t *driver, device_t parent)
 {
 	device_t child;
 
 	/* Make sure we're not being doubly invoked. */
 	if (device_find_child(parent, "amdsmn", -1) != NULL)
 		return;
 	if (!amdsmn_match(parent, NULL))
 		return;
 
 	child = device_add_child(parent, "amdsmn", DEVICE_UNIT_ANY);
 	if (child == NULL)
 		device_printf(parent, "add amdsmn child failed\n");
 }
 
 static int
 amdsmn_probe(device_t dev)
 {
 	uint32_t family;
 
 	if (resource_disabled("amdsmn", 0))
 		return (ENXIO);
 	if (!amdsmn_match(device_get_parent(dev), NULL))
 		return (ENXIO);
 
 	family = CPUID_TO_FAMILY(cpu_id);
 
 	switch (family) {
 	case 0x15:
 	case 0x17:
 	case 0x19:
 		break;
 	default:
 		return (ENXIO);
 	}
 	device_set_descf(dev, "AMD Family %xh System Management Network",
 	    family);
 
 	return (BUS_PROBE_GENERIC);
 }
 
 static int
 amdsmn_attach(device_t dev)
 {
 	struct amdsmn_softc *sc = device_get_softc(dev);
 
 	if (!amdsmn_match(device_get_parent(dev), &sc->smn_pciid))
 		return (ENXIO);
 
 	mtx_init(&sc->smn_lock, "SMN mtx", "SMN", MTX_DEF);
 	return (0);
 }
 
 int
 amdsmn_detach(device_t dev)
 {
 	struct amdsmn_softc *sc = device_get_softc(dev);
 
 	mtx_destroy(&sc->smn_lock);
 	return (0);
 }
 
 int
 amdsmn_read(device_t dev, uint32_t addr, uint32_t *value)
 {
 	struct amdsmn_softc *sc = device_get_softc(dev);
 	device_t parent;
 
 	parent = device_get_parent(dev);
 
 	mtx_lock(&sc->smn_lock);
 	pci_write_config(parent, sc->smn_pciid->amdsmn_addr_reg, addr, 4);
 	*value = pci_read_config(parent, sc->smn_pciid->amdsmn_data_reg, 4);
 	mtx_unlock(&sc->smn_lock);
 
 	return (0);
 }
 
 int
 amdsmn_write(device_t dev, uint32_t addr, uint32_t value)
 {
 	struct amdsmn_softc *sc = device_get_softc(dev);
 	device_t parent;
 
 	parent = device_get_parent(dev);
 
 	mtx_lock(&sc->smn_lock);
 	pci_write_config(parent, sc->smn_pciid->amdsmn_addr_reg, addr, 4);
 	pci_write_config(parent, sc->smn_pciid->amdsmn_data_reg, value, 4);
 	mtx_unlock(&sc->smn_lock);
 
 	return (0);
 }