[Serial] Split serial console from serial driver

src/core/serial_console.c

@@ -0,0 +1,31 @@
+#include <gpxe/init.h>
+#include <gpxe/serial.h>
+#include "console.h"
+
+/** @file
+ *
+ * Serial console
+ *
+ */
+
+struct console_driver serial_console __console_driver;
+
+static void serial_console_init ( void ) {
+	/* Serial driver initialization should already be done,
+	 * time to enable the serial console. */
+	serial_console.disabled = 0;
+}
+
+struct console_driver serial_console __console_driver = {
+	.putchar = serial_putc,
+	.getchar = serial_getc,
+	.iskey = serial_ischar,
+	.disabled = 1,
+};
+
+/**
+ * Serial console initialisation function
+ */
+struct init_fn serial_console_init_fn __init_fn ( INIT_CONSOLE ) = {
+	.initialise = serial_console_init,
+};