Move thunk code / snippets to a dedicated subdirectory

Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>

Makefile

@@ -131,7 +131,7 @@ PROGRESS := progress.c progress.h
 SOC_INFO := soc_info.c soc_info.h
 FEL_LIB  := fel_lib.c fel_lib.h
 
-sunxi-fel: fel.c fel-to-spl-thunk.h $(PROGRESS) $(SOC_INFO) $(FEL_LIB)
+sunxi-fel: fel.c thunks/fel-to-spl-thunk.h $(PROGRESS) $(SOC_INFO) $(FEL_LIB)
 	$(CC) $(HOST_CFLAGS) $(LIBUSB_CFLAGS) $(LDFLAGS) -o $@ $(filter %.c,$^) $(LIBS) $(LIBUSB_LIBS)
 
 sunxi-nand-part: nand-part-main.c nand-part.c nand-part-a10.h nand-part-a20.h

fel.c

@@ -216,7 +216,7 @@ void aw_fel_fill(feldev_handle *dev, uint32_t offset, size_t size, unsigned char
 }
 
 static uint32_t fel_to_spl_thunk[] = {
-	#include "fel-to-spl-thunk.h"
+	#include "thunks/fel-to-spl-thunk.h"
 };
 
 #define	DRAM_BASE		0x40000000

thunks/README.md

+
+# thunks/README.md
+
+This directory contains assembly sources for ARM [thunk] code, and
+a corresponding _Makefile_. The idea is that the resulting binary routines
+can be transferred to a suitable target device and then executed 'remotely',
+usually via `sunxi-fel`.
+
+Normally you don't need to change or (re)build anything within this folder.
+Currently our main build process (via the parent directory's _Makefile_)
+only includes `fel-to-spl-thunk.h` directly. Other _.h_ files are provided
+**just for reference**. The main purpose of this folder is simply keeping
+track of _.S_ sources, to help with possible future maintenance of the
+various code snippets.
+
+Please note that any files lacking explicit license information are intended
+to be covered by the project's [overall license](../LICENSE.md) (GPLv2).
+
+
+[thunk]: https://en.wikipedia.org/wiki/Thunk#Interoperability