On 18.01.2015 19:55, Simon Glass wrote:
At present SPL uses a single stack, either CONFIG_SPL_STACK or CONFIG_SYS_INIT_SP_ADDR. Since some SPL features (such as MMC and environment) require a lot of stack, some boards set CONFIG_SPL_STACK to point into SDRAM. They then set up SDRAM very early, before board_init_f(), so that the larger stack can be used.This is an abuse of lowlevel_init(). That function should only be used for essential start-up code which cannot be delayed. An example of a valid use is when only part of the SPL code is visible/executable, and the SoC must be set up so that board_init_f() can be reached. It should not be used for SDRAM init, console init, etc. Add a CONFIG_SPL_STACK_R option, which allows the stack to be moved to a new address before board_init_r() is called in SPL. The expected SPL flow (for CONFIG_SPL_FRAMEWORK) is now: Execution starts with start.S. Two main functions can be provided by the board implementation. The purpose and limitations of each is described below. After that, the common board_init_r() is called to perform the SPL task. lowlevel_init(): - purpose: essential init to permit execution to reach board_init_f() - no global_data, but there is a stack - must not set up SDRAM or use console - must only do the bare minimum to allow execution to continue to board_init_f() - this is almost never needed - return normally from this function board_init_f(): - purpose: set up the machine ready for running board_init_r(): i.e. SDRAM and serial UART - global_data is available - preloader_console_init() can be called here in extremis - stack is in SRAM - should set up SDRAM, and anything needed to make the UART work - these is no need to clear BSS, it will be done by crt0.S - must return normally from this function (don't call board_init_r() directly) Here the BSS is cleared. If CONFIG_SPL_STACK_R is defined, then at this point the stack and global_data are relocated to below that address. board_init_r(): - purpose: main execution, common code - global_data is available - SDRAM is available - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and points into SDRAM - preloader_console_init() can be called here - typically this is done by defining CONFIG_SPL_BOARD_INIT and then supplying a spl_board_init() function containing this call - loads U-Boot or (in falcon mode) Linux Note: This patch is intended to apply over the top of Tom's SPL changes and this series: https://patchwork.ozlabs.org/patch/423785/ Signed-off-by: Simon Glass <s...@chromium.org>
Reviewed-by: Stefan Roese <s...@denx.de> Thanks, Stefan _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
