Add a bit more information about how to use SPL.
Signed-off-by: Simon Glass sjg@chromium.org ---
(no changes since v1)
doc/develop/spl.rst | 59 +++++++++++++++++++++++++++------------------ 1 file changed, 36 insertions(+), 23 deletions(-)
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index 1165f95335f..c2a29a8c0a4 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -42,29 +42,42 @@ 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_FS_FAT (fs/fat/libfat.o) -CONFIG_SPL_FS_EXT4 -CONFIG_SPL_LIBGENERIC_SUPPORT (lib/libgeneric.o) -CONFIG_SPL_POWER_SUPPORT (drivers/power/libpower.o) -CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/raw/libnand.o) -CONFIG_SPL_DRIVERS_MISC_SUPPORT (drivers/misc) -CONFIG_SPL_DMA (drivers/dma/libdma.o) -CONFIG_SPL_POST_MEM_SUPPORT (post/drivers/memory.o) -CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/raw/nand_spl_load.o) -CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o) -CONFIG_SPL_RAM_DEVICE (common/spl/spl.c) -CONFIG_SPL_WATCHDOG_SUPPORT (drivers/watchdog/libwatchdog.o) +optionally define CONFIG_SPL_XXX_SUPPORT (or CONFIG_SPL_XXX_SUPPORT for older +options). + +Adding SPL-specific code +------------------------ + +To check whether a feature is enabled, use CONFIG_IS_ENABLED():: + + if (CONFIG_IS_ENABLED(CLK)) + ... + +This checks CONFIG_CLK for the main build, CONFIG_SPL_CLK for the SPL build, +CONFIG_TPL_CLK for the TPL build, etc. + +U-Boot Phases +------------- + +U-Boot boots through the following phases: + +TPL + Very early init, as tiny as possible. This loads SPL. + +SPL + Secondary program loader. Sets up SDRAM and loads U-Boot proper. It may also + load other firmware components. + +U-Boot + U-Boot proper, containing the command line and boot logic. + + +Checking the boot phase +----------------------- + +Use `spl_phase()` to find the current U-Boot phase, e.g. `PHASE_SPL`. You can +also find the previous and next phase and get the phase name. +
Device tree -----------