spl: add initial support for a generic SPL framework

Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>

README

@@ -2255,6 +2255,45 @@ FIT uImage format:
 		Adds the MTD partitioning infrastructure from the Linux
 		kernel. Needed for UBI support.
 
+- SPL framework
+                CONFIG_SPL
+                Enable building of SPL globally.
+
+                CONFIG_SPL_TEXT_BASE
+                TEXT_BASE for linking the SPL binary.
+
+                CONFIG_SPL_LDSCRIPT
+                LDSCRIPT for linking the SPL binary.
+
+                CONFIG_SPL_LIBCOMMON_SUPPORT
+                Support for common/libcommon.o in SPL binary
+
+                CONFIG_SPL_LIBDISK_SUPPORT
+                Support for disk/libdisk.o in SPL binary
+
+                CONFIG_SPL_I2C_SUPPORT
+                Support for drivers/i2c/libi2c.o in SPL binary
+
+                CONFIG_SPL_GPIO_SUPPORT
+                Support for drivers/gpio/libgpio.o in SPL binary
+
+                CONFIG_SPL_MMC_SUPPORT
+                Support for drivers/mmc/libmmc.o in SPL binary
+
+                CONFIG_SPL_SERIAL_SUPPORT
+                Support for drivers/serial/libserial.o in SPL binary
+
+                CONFIG_SPL_SPI_FLASH_SUPPORT
+                Support for drivers/mtd/spi/libspi_flash.o in SPL binary
+
+                CONFIG_SPL_SPI_SUPPORT
+                Support for drivers/spi/libspi.o in SPL binary
+
+                CONFIG_SPL_FAT_SUPPORT
+                Support for fs/fat/libfat.o in SPL binary
+
+                CONFIG_SPL_LIBGENERIC_SUPPORT
+                Support for lib/libgeneric.o in SPL binary
 
 Modem Support:
 --------------

doc/README.SPL

+Generic SPL framework
+=====================
+
+Overview
+--------
+
+To unify all existing implementations for a secondary program loader (SPL)
+and to allow simply adding of new implementations this generic SPL framework
+has been created. With this framework almost all source files for a board
+can be reused. No code duplication or symlinking is necessary anymore.
+
+
+How it works
+------------
+
+There is a new directory TOPDIR/spl which contains only a Makefile.
+The object files are built separately for SPL and placed in this directory.
+The final binaries which are generated are u-boot-spl, u-boot-spl.bin and
+u-boot-spl.map.
+
+During the SPL build a variable named CONFIG_SPL_BUILD is exported
+in the make environment and also appended to CPPFLAGS with -DCONFIG_SPL_BUILD.
+Source files can therefore be compiled for SPL with different settings.
+ARM-based boards have previously used the option CONFIG_PRELOADER for it.
+
+For example:
+
+ifeq ($(CONFIG_SPL_BUILD),y)
+COBJS-y += board_spl.o
+else
+COBJS-y += board.o
+endif
+
+COBJS-$(CONFIG_SPL_BUILD) += foo.o
+
+#ifdef CONFIG_SPL_BUILD
+        foo();
+#endif
+
+
+The building of SPL images can be with:
+
+#define CONFIG_SPL
+
+Because SPL images normally have a different text base, one have to be
+configured by defining CONFIG_SPL_TEXT_BASE. The linker script have to be
+defined with CONFIG_SPL_LDSCRIPT.
+
+To support generic U-Boot libraries and drivers in the SPL binary one can
+optionally define CONFIG_SPL_XXX_SUPPORT. Currently following options
+are supported:
+
+CONFIG_SPL_LIBCOMMON_SUPPORT (common/libcommon.o)
+CONFIG_SPL_LIBDISK_SUPPORT (disk/libdisk.o)
+CONFIG_SPL_I2C_SUPPORT (drivers/i2c/libi2c.o)
+CONFIG_SPL_GPIO_SUPPORT (drivers/gpio/libgpio.o)
+CONFIG_SPL_MMC_SUPPORT (drivers/mmc/libmmc.o)
+CONFIG_SPL_SERIAL_SUPPORT (drivers/serial/libserial.o)
+CONFIG_SPL_SPI_FLASH_SUPPORT (drivers/mtd/spi/libspi_flash.o)
+CONFIG_SPL_SPI_SUPPORT (drivers/spi/libspi.o)
+CONFIG_SPL_FAT_SUPPORT (fs/fat/libfat.o)
+CONFIG_SPL_LIBGENERIC_SUPPORT (lib/libgeneric.o)

spl/.gitignore

+u-boot-spl
+u-boot-spl.bin
+u-boot-spl.lds
+u-boot-spl.map

spl/Makefile

+#
+# (C) Copyright 2000-2011
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+#
+# (C) Copyright 2011
+# Daniel Schwierzeck, daniel.schwierzeck@googlemail.com.
+#
+# (C) Copyright 2011
+# Texas Instruments Incorporated - http://www.ti.com/
+# Aneesh V <aneesh@ti.com>
+#
+# This file is released under the terms of GPL v2 and any later version.
+# See the file COPYING in the root directory of the source tree for details.
+#
+# Based on top-level Makefile.
+#
+
+CONFIG_SPL_BUILD := y
+export CONFIG_SPL_BUILD
+
+include $(TOPDIR)/config.mk
+
+# We want the final binaries in this directory
+obj := $(OBJTREE)/spl/
+
+HAVE_VENDOR_COMMON_LIB := $(shell [ -f $(SRCTREE)/board/$(VENDOR)/common/Makefile ] \
+			&& echo y || echo n)
+
+START := $(CPUDIR)/start.o
+
+LIBS-y += arch/$(ARCH)/lib/lib$(ARCH).o
+LIBS-y += $(CPUDIR)/lib$(CPU).o
+ifdef SOC
+LIBS-y += $(CPUDIR)/$(SOC)/lib$(SOC).o
+endif
+LIBS-y += board/$(BOARDDIR)/lib$(BOARD).o
+LIBS-$(HAVE_VENDOR_COMMON_LIB) += board/$(VENDOR)/common/lib$(VENDOR).o
+
+START := $(addprefix $(SPLTREE)/,$(START))
+LIBS := $(addprefix $(SPLTREE)/,$(sort $(LIBS-y)))
+
+__START := $(subst $(obj),,$(START))
+__LIBS := $(subst $(obj),,$(LIBS))
+
+# Linker Script
+ifdef CONFIG_SPL_LDSCRIPT
+# need to strip off double quotes
+LDSCRIPT := $(addprefix $(SRCTREE)/,$(subst ",,$(CONFIG_SPL_LDSCRIPT)))
+endif
+
+ifeq ($(wildcard $(LDSCRIPT)),)
+	LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot-spl.lds
+endif
+ifeq ($(wildcard $(LDSCRIPT)),)
+	LDSCRIPT := $(TOPDIR)/$(CPUDIR)/u-boot-spl.lds
+endif
+ifeq ($(wildcard $(LDSCRIPT)),)
+$(error could not find linker script)
+endif
+
+# Special flags for CPP when processing the linker script.
+# Pass the version down so we can handle backwards compatibility
+# on the fly.
+LDPPFLAGS += \
+	-include $(TOPDIR)/include/u-boot/u-boot.lds.h \
+	-include $(OBJTREE)/include/config.h \
+	$(shell $(LD) --version | \
+	  sed -ne 's/GNU ld version \([0-9][0-9]*\)\.\([0-9][0-9]*\).*/-DLD_MAJOR=\1 -DLD_MINOR=\2/p')
+
+ALL-y	+= $(obj)u-boot-spl.bin
+
+all:	$(ALL-y)
+
+$(obj)u-boot-spl.bin:	$(obj)u-boot-spl
+	$(OBJCOPY) $(OBJCFLAGS) -O binary $< $@
+
+GEN_UBOOT = \
+	UNDEF_SYM=`$(OBJDUMP) -x $(LIBS) | \
+	sed  -n -e 's/.*\($(SYM_PREFIX)__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\
+	cd $(obj) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) $$UNDEF_SYM $(__START) \
+		--start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \
+		-Map u-boot-spl.map -o u-boot-spl
+
+$(obj)u-boot-spl:	depend $(START) $(LIBS) $(obj)u-boot-spl.lds
+	$(GEN_UBOOT)
+
+$(START):	depend
+	$(MAKE) -C $(SRCTREE)/$(CPUDIR) $@
+
+$(LIBS):	depend
+	$(MAKE) -C $(SRCTREE)$(dir $(subst $(SPLTREE),,$@))
+
+$(obj)u-boot-spl.lds: $(LDSCRIPT) depend
+	$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - < $< > $@
+
+depend:	$(obj).depend
+.PHONY: depend
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk