Index: sys/dev/uart/uart_cpu_arm64.c
===================================================================
--- sys/dev/uart/uart_cpu_arm64.c
+++ sys/dev/uart/uart_cpu_arm64.c
@@ -149,9 +149,23 @@
 
 	*classp = cd->cd_class;
 	*rclk = 0;
-	*shiftp = 2;
 	*iowidthp = spcr->SerialPort.BitWidth / 8;
 
+	switch (spcr->InterfaceType) {
+	case ACPI_DBG2_ARM_PL011:
+	case ACPI_DBG2_ARM_SBSA_32BIT:
+	case ACPI_DBG2_ARM_SBSA_GENERIC:
+		*shiftp = 2;
+		break;
+	case ACPI_DBG2_16550_COMPATIBLE:
+	case ACPI_DBG2_16550_SUBSET:
+		*shiftp = 0;
+		break;
+	default:
+		printf("uart_cpu_acpi_probe: unknown InterfaceType %d",
+			spcr->InterfaceType);
+	}
+
 out:
 	acpi_unmap_table(spcr);
 	return (err);