diff --git a/src/superio/winbond/common/early_serial.c b/src/superio/winbond/common/early_serial.c
index 6482a94838..aebbd38b46 100644
--- a/src/superio/winbond/common/early_serial.c
+++ b/src/superio/winbond/common/early_serial.c
@@ -66,3 +66,16 @@ void winbond_enable_serial(pnp_devfn_t dev, u16 iobase)
 	pnp_set_enable(dev, 1);
 	pnp_exit_conf_state(dev);
 }
+
+void winbond_set_pinmux(pnp_devfn_t dev, uint8_t offset, uint8_t mask, uint8_t state)
+{
+	uint8_t byte;
+
+	/* Configure pin mux */
+	pnp_enter_conf_state(dev);
+	byte = pnp_read_config(dev, offset);
+	byte &= ~mask;
+	byte |= state;
+	pnp_write_config(dev, offset, byte);
+	pnp_exit_conf_state(dev);
+}
diff --git a/src/superio/winbond/common/winbond.h b/src/superio/winbond/common/winbond.h
index 1f7e7b1794..6e67eeb83d 100644
--- a/src/superio/winbond/common/winbond.h
+++ b/src/superio/winbond/common/winbond.h
@@ -20,7 +20,8 @@
 #include <arch/io.h>
 #include <stdint.h>
 
-void winbond_enable_serial(pnp_devfn_t dev, u16 iobase);
+void winbond_enable_serial(pnp_devfn_t dev, uint16_t iobase);
+void winbond_set_pinmux(pnp_devfn_t dev, uint8_t offset, uint8_t mask, uint8_t state);
 
 void pnp_enter_conf_state(pnp_devfn_t dev);
 void pnp_exit_conf_state(pnp_devfn_t dev);