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/drivers/sound/sound.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2012 Samsung Electronics
+ * R. Chandrasekar <rcsekar@samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <sound.h>
+
+void sound_create_square_wave(unsigned short *data, int size, uint32_t freq)
+{
+	const int sample = 48000;
+	const unsigned short amplitude = 16000; /* between 1 and 32767 */
+	const int period = freq ? sample / freq : 0;
+	const int half = period / 2;
+
+	assert(freq);
+
+	/* Make sure we don't overflow our buffer */
+	if (size % 2)
+		size--;
+
+	while (size) {
+		int i;
+		for (i = 0; size && i < half; i++) {
+			size -= 2;
+			*data++ = amplitude;
+			*data++ = amplitude;
+		}
+		for (i = 0; size && i < period - half; i++) {
+			size -= 2;
+			*data++ = -amplitude;
+			*data++ = -amplitude;
+		}
+	}
+}