avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/arch/x86/lib/i8254.c

@@ -0,0 +1,37 @@
+/*
+ * (C) Copyright 2002
+ * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/i8254.h>
+
+#define TIMER1_VALUE	18	/* 15.6us */
+#define TIMER2_VALUE	0x0a8e	/* 440Hz */
+
+int i8254_init(void)
+{
+	/*
+	 * Initialize counter 1, used to refresh request signal.
+	 * This is required for legacy purpose as some codes like
+	 * vgabios utilizes counter 1 to provide delay functionality.
+	 */
+	outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
+	     PIT_BASE + PIT_COMMAND);
+	outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
+
+	/*
+	 * Initialize counter 2, used to drive the speaker.
+	 * To start a beep, set both bit0 and bit1 of port 0x61.
+	 * To stop it, clear both bit0 and bit1 of port 0x61.
+	 */
+	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
+	     PIT_BASE + PIT_COMMAND);
+	outb(TIMER2_VALUE & 0xff, PIT_BASE + PIT_T2);
+	outb(TIMER2_VALUE >> 8, PIT_BASE + PIT_T2);
+
+	return 0;
+}