sio/winbond: Expose enter/exit configuration state functions

Certain mainboards, e.g. the ASUS KGPE-D16/KCMA-D8, require
board-specific configuration changes to the SuperIO.  Expose
the functions needed to enter and exit configuration mode
on Winbond devices.

Change-Id: Ic86651872ecafcfe1398201be2b0768bbe460975
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: https://review.coreboot.org/14891
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/superio/winbond/common/early_serial.c

@@ -42,15 +42,15 @@
 #define WINBOND_EXIT_KEY 0xAA
 
 /* Enable configuration: pass entry key '0x87' into index port dev. */
-static void pnp_enter_conf_state(pnp_devfn_t dev)
+void pnp_enter_conf_state(pnp_devfn_t dev)
 {
 	u16 port = dev >> 8;
 	outb(WINBOND_ENTRY_KEY, port);
 	outb(WINBOND_ENTRY_KEY, port);
 }
 
 /* Disable configuration: pass exit key '0xAA' into index port dev. */
-static void pnp_exit_conf_state(pnp_devfn_t dev)
+void pnp_exit_conf_state(pnp_devfn_t dev)
 {
 	u16 port = dev >> 8;
 	outb(WINBOND_EXIT_KEY, port);

src/superio/winbond/common/winbond.h

@@ -22,4 +22,7 @@
 
 void winbond_enable_serial(pnp_devfn_t dev, u16 iobase);
 
+void pnp_enter_conf_state(pnp_devfn_t dev);
+void pnp_exit_conf_state(pnp_devfn_t dev);
+
 #endif /* SUPERIO_WINBOND_COMMON_ROMSTAGE_H */