lib: utils: Add simple FDT serial framework

We add simple serial framework which will select and use serial driver
based on details in FDT passed by previous booting stage.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

include/sbi_utils/serial/fdt_serial.h

@@ -0,0 +1,28 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __FDT_SERIAL_H__
+#define __FDT_SERIAL_H__
+
+#include <sbi/sbi_types.h>
+
+struct fdt_serial {
+	const struct fdt_match *match_table;
+	int (*init)(void *fdt, int nodeoff, const struct fdt_match *match);
+	void (*putc)(char ch);
+	int (*getc)(void);
+};
+
+void fdt_serial_putc(char ch);
+
+int fdt_serial_getc(void);
+
+int fdt_serial_init(void);
+
+#endif