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/twserial/soft_tws.c

@@ -0,0 +1,94 @@
+/*
+ * (C) Copyright 2009
+ * Detlev Zundel, DENX Software Engineering, dzu@denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#define TWS_IMPLEMENTATION
+#include <common.h>
+
+/*=====================================================================*/
+/*                         Public Functions                            */
+/*=====================================================================*/
+
+/*-----------------------------------------------------------------------
+ * Read bits
+ */
+int tws_read(uchar *buffer, int len)
+{
+	int rem = len;
+	uchar accu, shift;
+
+	debug("tws_read: buffer %p len %d\n", buffer, len);
+
+	/* Configure the data pin for input */
+	tws_data_config_output(0);
+
+	/* Disable WR, i.e. setup a read */
+	tws_wr(0);
+	udelay(1);
+
+	/* Rise CE */
+	tws_ce(1);
+	udelay(1);
+
+	for (; rem > 0; ) {
+		for (shift = 0, accu = 0;
+		     (rem > 0) && (shift < 8);
+		     rem--, shift++) {
+			tws_clk(1);
+			udelay(10);
+			accu |= (tws_data_read() << shift); /* LSB first */
+			tws_clk(0);
+			udelay(10);
+		}
+		*buffer++ = accu;
+	}
+
+	/* Lower CE */
+	tws_ce(0);
+
+	return len - rem;
+}
+
+
+/*-----------------------------------------------------------------------
+ * Write bits
+ */
+int tws_write(uchar *buffer, int len)
+{
+	int rem = len;
+	uchar accu, shift;
+
+	debug("tws_write: buffer %p len %d\n", buffer, len);
+
+	/* Configure the data pin for output */
+	tws_data_config_output(1);
+
+	/* Enable WR, i.e. setup a write */
+	tws_wr(1);
+	udelay(1);
+
+	/* Rise CE */
+	tws_ce(1);
+	udelay(1);
+
+	for (; rem > 0; ) {
+		for (shift = 0, accu = *buffer++;
+		     (rem > 0) && (shift < 8);
+		     rem--, shift++) {
+			tws_data(accu & 0x01); /* LSB first */
+			tws_clk(1);
+			udelay(10);
+			tws_clk(0);
+			udelay(10);
+			accu >>= 1;
+		}
+	}
+
+	/* Lower CE */
+	tws_ce(0);
+
+	return len - rem;
+}