69 lines
2.2 KiB
Plaintext
69 lines
2.2 KiB
Plaintext
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 has to be
|
|
configured by defining CONFIG_SPL_TEXT_BASE. The linker script has 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)
|
|
CONFIG_SPL_POWER_SUPPORT (drivers/power/libpower.o)
|
|
CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/libnand.o)
|
|
CONFIG_SPL_DMA_SUPPORT (drivers/dma/libdma.o)
|
|
CONFIG_SPL_POST_MEM_SUPPORT (post/drivers/memory.o)
|
|
CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/nand_spl_load.o)
|
|
CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)
|