diff --git a/sys/dev/amdsmu/amdsmu.h b/sys/dev/amdsmu/amdsmu.h
--- a/sys/dev/amdsmu/amdsmu.h
+++ b/sys/dev/amdsmu/amdsmu.h
@@ -25,10 +25,20 @@
 static const struct amdsmu_product {
 	uint16_t	amdsmu_vendorid;
 	uint16_t	amdsmu_deviceid;
+	int16_t		idlemask_reg;
+	size_t		ip_block_count;
 } amdsmu_products[] = {
-	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_REMBRANDT_ROOT },
-	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_PHOENIX_ROOT },
-	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_STRIX_POINT_ROOT },
+	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_CEZANNE_ROOT,
+	    SMU_REG_IDLEMASK_CEZANNE,	12 },
+	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_REMBRANDT_ROOT,
+	    SMU_REG_IDLEMASK_PHOENIX,	12 },
+	{ CPU_VENDOR_AMD,	PCI_DEVICEID_AMD_PHOENIX_ROOT,
+	    SMU_REG_IDLEMASK_PHOENIX,	21 },
+	/*
+	 * XXX Strix Point (PCI_DEVICEID_AMD_STRIX_POINT_ROOT) doesn't support
+	 * S0i3 and thus doesn't have an idlemask.  Since our driver doesn't
+	 * yet understand this, don't attach to Strix Point for the time being.
+	 */
 };
 
 static const char *const amdsmu_ip_blocks_names[] = {
@@ -59,6 +69,8 @@
 CTASSERT(nitems(amdsmu_ip_blocks_names) <= 32);
 
 struct amdsmu_softc {
+	const struct amdsmu_product	*product;
+
 	struct sysctl_ctx_list	*sysctlctx;
 	struct sysctl_oid	*sysctlnode;
 
@@ -76,7 +88,6 @@
 
 	uint32_t		active_ip_blocks;
 	struct sysctl_oid	*ip_blocks_sysctlnode;
-	size_t			ip_block_count;
 	struct sysctl_oid	*ip_block_sysctlnodes[
 				    nitems(amdsmu_ip_blocks_names)];
 	bool			ip_blocks_active[
diff --git a/sys/dev/amdsmu/amdsmu.c b/sys/dev/amdsmu/amdsmu.c
--- a/sys/dev/amdsmu/amdsmu.c
+++ b/sys/dev/amdsmu/amdsmu.c
@@ -58,9 +58,12 @@
 static int
 amdsmu_probe(device_t dev)
 {
+	struct amdsmu_softc *sc;
+
 	if (resource_disabled("amdsmu", 0))
 		return (ENXIO);
-	if (!amdsmu_match(device_get_parent(dev), NULL))
+	sc = device_get_softc(dev);
+	if (!amdsmu_match(device_get_parent(dev), &sc->product))
 		return (ENXIO);
 	device_set_descf(dev, "AMD System Management Unit");
 
@@ -154,28 +157,11 @@
 amdsmu_get_ip_blocks(device_t dev)
 {
 	struct amdsmu_softc *sc = device_get_softc(dev);
-	const uint16_t deviceid = pci_get_device(dev);
 	int err;
 	struct amdsmu_metrics *m = &sc->metrics;
 	bool active;
 	char sysctl_descr[32];
 
-	/* Get IP block count. */
-	switch (deviceid) {
-	case PCI_DEVICEID_AMD_REMBRANDT_ROOT:
-		sc->ip_block_count = 12;
-		break;
-	case PCI_DEVICEID_AMD_PHOENIX_ROOT:
-		sc->ip_block_count = 21;
-		break;
-	/* TODO How many IP blocks does Strix Point (and the others) have? */
-	case PCI_DEVICEID_AMD_STRIX_POINT_ROOT:
-	default:
-		sc->ip_block_count = nitems(amdsmu_ip_blocks_names);
-	}
-	KASSERT(sc->ip_block_count <= nitems(amdsmu_ip_blocks_names),
-	    ("too many IP blocks for array"));
-
 	/* Get and print out IP blocks. */
 	err = amdsmu_cmd(dev, SMU_MSG_GET_SUP_CONSTRAINTS, 0,
 	    &sc->active_ip_blocks);
@@ -184,13 +170,13 @@
 		return (err);
 	}
 	device_printf(dev, "Active IP blocks: ");
-	for (size_t i = 0; i < sc->ip_block_count; i++) {
+	for (size_t i = 0; i < sc->product->ip_block_count; i++) {
 		active = (sc->active_ip_blocks & (1 << i)) != 0;
 		sc->ip_blocks_active[i] = active;
 		if (!active)
 			continue;
 		printf("%s%s", amdsmu_ip_blocks_names[i],
-		    i + 1 < sc->ip_block_count ? " " : "\n");
+		    i + 1 < sc->product->ip_block_count ? " " : "\n");
 	}
 
 	/* Create a sysctl node for IP blocks. */
@@ -203,7 +189,7 @@
 	}
 
 	/* Create a sysctl node for each IP block. */
-	for (size_t i = 0; i < sc->ip_block_count; i++) {
+	for (size_t i = 0; i < sc->product->ip_block_count; i++) {
 		/* Create the sysctl node itself for the IP block. */
 		snprintf(sysctl_descr, sizeof sysctl_descr,
 		    "Metrics about the %s AMD IP block",
@@ -293,7 +279,7 @@
 {
 	struct amdsmu_softc *sc = device_get_softc(dev);
 
-	sc->idlemask = amdsmu_read4(sc, SMU_REG_IDLEMASK);
+	sc->idlemask = amdsmu_read4(sc, sc->product->idlemask_reg);
 }
 
 static void
@@ -301,6 +287,10 @@
 {
 	if (stype != POWER_STYPE_SUSPEND_TO_IDLE)
 		return;
+	/*
+	 * XXX It seems that Cezanne needs a special workaround here for
+	 * firmware versions < 64.53.  See amd_pmc_verify_czn_rtc() in Linux.
+	 */
 	if (amdsmu_cmd(dev, SMU_MSG_SLEEP_HINT, true, NULL) != 0)
 		device_printf(dev, "failed to hint to SMU to enter sleep");
 }
diff --git a/sys/dev/amdsmu/amdsmu_reg.h b/sys/dev/amdsmu/amdsmu_reg.h
--- a/sys/dev/amdsmu/amdsmu_reg.h
+++ b/sys/dev/amdsmu/amdsmu_reg.h
@@ -16,6 +16,7 @@
  * out?  Also, there are way more of these.  I couldn't find a centralized place
  * which lists them though.
  */
+#define PCI_DEVICEID_AMD_CEZANNE_ROOT		0x1630
 #define PCI_DEVICEID_AMD_REMBRANDT_ROOT		0x14B5
 #define PCI_DEVICEID_AMD_PHOENIX_ROOT		0x14E8
 #define PCI_DEVICEID_AMD_STRIX_POINT_ROOT	0x14A4
@@ -32,7 +33,9 @@
 #define SMU_REG_MESSAGE		0x538
 #define SMU_REG_RESPONSE	0x980
 #define SMU_REG_ARGUMENT	0x9BC
-#define SMU_REG_IDLEMASK	0xD14
+
+#define SMU_REG_IDLEMASK_CEZANNE	0x94
+#define SMU_REG_IDLEMASK_PHOENIX	0xD14
 
 enum amdsmu_res {
 	SMU_RES_WAIT		= 0x00,