superio: Add ASpeed AST2400

Add support for ASpeed AST2400.
This device uses write twice 0xA5 to enter config mode.

BUG = N/A
TEST = ASRock D1521D4U

Change-Id: I58fce31f0a2483e61e9d31f38ab5a059b8cf4f83
Signed-off-by: Frans Hendriks <fhendriks@eltan.com>
Signed-off-by: Felix Singer <migy@darmstadt.ccc.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/23135
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/superio/aspeed/common/aspeed.h

@@ -0,0 +1,30 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 Edward O'Callaghan <eocallaghan@alterapraxis.com>
+ * Copyright (C) 2018 Eltan B.V.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef SUPERIO_ASPEED_COMMON_ROMSTAGE_H
+#define SUPERIO_ASPEED_COMMON_ROMSTAGE_H
+
+#include <arch/io.h>
+#include <device/pnp_type.h>
+#include <stdint.h>
+
+void aspeed_enable_serial(pnp_devfn_t dev, uint16_t iobase);
+
+void pnp_enter_conf_state(pnp_devfn_t dev);
+void pnp_exit_conf_state(pnp_devfn_t dev);
+
+#endif /* SUPERIO_ASPEED_COMMON_ROMSTAGE_H */