Blackfin: add init.elf helper code

This creates a standalone ELF that executes just the Blackfin initcode.
This is useful for people who want to program the low level aspects of
the CPU (memory/clocks/etc...) and can easily be used with JTAG for
quick booting while developing.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

Makefile

@@ -1075,7 +1075,8 @@ clean:
 	       $(obj)board/voiceblue/eeprom 				  \
 	       $(obj)board/armltd/{integratorap,integratorcp}/u-boot.lds  \
 	       $(obj)u-boot.lds						  \
-	       $(obj)arch/blackfin/cpu/bootrom-asm-offsets.[chs]
+	       $(obj)arch/blackfin/cpu/bootrom-asm-offsets.[chs]	  \
+	       $(obj)arch/blackfin/cpu/init.{lds,elf}
 	@rm -f $(obj)include/bmp_logo.h
 	@rm -f $(obj)lib/asm-offsets.s
 	@rm -f $(obj)nand_spl/{u-boot.lds,u-boot-nand_spl.lds,u-boot-spl,u-boot-spl.map,System.map}

arch/blackfin/cpu/.gitignore

 bootrom-asm-offsets.[chs]
+
+init.lds
+init.elf

arch/blackfin/cpu/Makefile

@@ -13,7 +13,7 @@ include $(TOPDIR)/config.mk
 
 LIB	= $(obj)lib$(CPU).o
 
-EXTRA    :=
+EXTRA    := init.elf
 CEXTRA   := initcode.o
 SEXTRA   := start.o
 SOBJS    := interrupt.o cache.o
@@ -61,6 +61,11 @@ ifneq ($(CONFIG_BFIN_BOOT_MODE),BFIN_BOOT_BYPASS)
 	fi
 endif
 
+$(obj)init.lds: init.lds.S
+	$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P $^ -o $@
+$(obj)init.elf: $(obj)init.lds $(obj)init.o $(obj)initcode.o
+	$(LD) $(LDFLAGS) -T $^ -o $@
+
 #########################################################################
 
 # defines $(obj).depend target

arch/blackfin/cpu/init.S

+#include <asm/blackfin.h>
+ENTRY(_start)
+	sp.l = LO(L1_SRAM_SCRATCH_END - 20);
+	sp.h = HI(L1_SRAM_SCRATCH_END - 20);
+	call _initcode;
+1:
+	emuexcpt;
+	jump 1b;
+END(_start)

arch/blackfin/cpu/init.lds.S

+/*
+ * linker script for simple init.elf
+ *
+ * Copyright (c) 2005-2011 Analog Device Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <config.h>
+#include <asm/blackfin.h>
+#undef ALIGN
+#undef ENTRY
+
+OUTPUT_ARCH(bfin)
+
+MEMORY
+{
+	l1_code : ORIGIN = L1_INST_SRAM, LENGTH = L1_INST_SRAM_SIZE
+}
+
+ENTRY(_start)
+SECTIONS
+{
+	.text.l1 : { *(.text .text.*) } >l1_code
+}