diff --git a/src/superio/nuvoton/common/nuvoton.h b/src/superio/nuvoton/common/nuvoton.h
index eb5bc759f3..0243c69b3e 100644
--- a/src/superio/nuvoton/common/nuvoton.h
+++ b/src/superio/nuvoton/common/nuvoton.h
@@ -1,13 +1,28 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
-#ifndef SUPERIO_NUVOTON_COMMON_PRE_RAM_H
-#define SUPERIO_NUVOTON_COMMON_PRE_RAM_H
+#ifndef SUPERIO_NUVOTON_COMMON_H
+#define SUPERIO_NUVOTON_COMMON_H
 
+#ifndef __ACPI__
 #include <device/pnp_type.h>
 #include <stdint.h>
 
 void nuvoton_pnp_enter_conf_state(pnp_devfn_t dev);
 void nuvoton_pnp_exit_conf_state(pnp_devfn_t dev);
 void nuvoton_enable_serial(pnp_devfn_t dev, u16 iobase);
+#endif
 
-#endif /* SUPERIO_NUVOTON_COMMON_PRE_RAM_H */
+/*
+ * Logical Device Numbers (LDN) common to all Nuvoton SIOs.
+ * Because they will be incorporated into ACPI device IDs,
+ * they must be written as decimal.
+ */
+#define NCT677X_PP		1 /* Parallel port */
+#define NCT677X_SP1		2 /* COM1 */
+#define NCT677X_SP2		3 /* COM2 & IR */
+#define NCT677X_KBC		5 /* PS/2 keyboard and mouse */
+#define NCT677X_ACPI		10 /* ACPI */
+#define NCT677X_HWM_FPLED	11 /* Hardware monitor & front LED */
+#define NCT677X_MAXLDN		22 /* The highest known LDN of these chips (0x16) */
+
+#endif /* SUPERIO_NUVOTON_COMMON_H */