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/powerpc/cpu/ppc4xx/kgdb.S

@@ -0,0 +1,60 @@
+/*
+ *  Copyright (C) 2000	Murray Jensen <Murray.Jensen@cmst.csiro.au>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <command.h>
+#include <asm/ppc4xx.h>
+
+#define CONFIG_405GP 1		/* needed for Linux kernel header files */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+
+#include <asm/cache.h>
+#include <asm/mmu.h>
+
+#if defined(CONFIG_CMD_KGDB)
+ /*
+ * cache flushing routines for kgdb
+ */
+
+	.globl	kgdb_flush_cache_all
+kgdb_flush_cache_all:
+	/* icache */
+	iccci   r0,r0		/* iccci invalidates the entire I cache */
+	/* dcache */
+	addi    r6,0,0x0000     /* clear GPR 6 */
+	addi    r7,r0, 128	/* do loop for # of dcache lines */
+				/* NOTE: dccci invalidates both */
+	mtctr   r7              /* ways in the D cache */
+..dcloop:
+	dccci   0,r6            /* invalidate line */
+	addi    r6,r6, 32	/* bump to next line */
+	bdnz    ..dcloop
+	blr
+
+	.globl	kgdb_flush_cache_range
+kgdb_flush_cache_range:
+	li	r5,L1_CACHE_BYTES-1
+	andc	r3,r3,r5
+	subf	r4,r3,r4
+	add	r4,r4,r5
+	srwi.	r4,r4,L1_CACHE_SHIFT
+	beqlr
+	mtctr	r4
+	mr	r6,r3
+1:	dcbst	0,r3
+	addi	r3,r3,L1_CACHE_BYTES
+	bdnz	1b
+	sync			/* wait for dcbst's to get to ram */
+	mtctr	r4
+2:	icbi	0,r6
+	addi	r6,r6,L1_CACHE_BYTES
+	bdnz	2b
+	SYNC
+	blr
+
+#endif