Hi Simon,
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 sjg@chromium.org
arch/arm/lib/crt0.S | 13 ++++++++++--- common/spl/spl.c | 35 +++++++++++++++++++++++++++++++++++ doc/README.SPL | 42 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 87 insertions(+), 3 deletions(-)
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S index 22df3e5..7939ced 100644 --- a/arch/arm/lib/crt0.S +++ b/arch/arm/lib/crt0.S @@ -113,7 +113,14 @@ here: /* Set up final (full) environment */
bl c_runtime_cpu_setup /* we still call old routine here */
+#endif +#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK) +# ifdef CONFIG_SPL_BUILD
- /* Use a DRAM stack for the rest of SPL, if requested */
- bl spl_relocate_stack_gd
- cmp r0, #0
- movne sp, r0
+# endif ldr r0, =__bss_start /* this is auto-relocated! */ ldr r1, =__bss_end /* this is auto-relocated! */
@@ -124,9 +131,10 @@ clbss_l:cmp r0, r1 /* while not at end of BSS */ addlo r0, r0, #4 /* move to next */ blo clbss_l
+#if ! defined(CONFIG_SPL_BUILD) bl coloured_LED_init bl red_led_on
+#endif /* call board_init_r(gd_t *id, ulong dest_addr) */ mov r0, r9 /* gd_t */ ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */ @@ -134,7 +142,6 @@ clbss_l:cmp r0, r1 /* while not at end of BSS */ ldr pc, =board_init_r /* this is auto-relocated! */
/* we should not return here. */
#endif
ENDPROC(_main) diff --git a/common/spl/spl.c b/common/spl/spl.c index 1826c47..78bb279 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -276,3 +276,38 @@ void preloader_console_init(void) spl_display_print(); #endif }
+/**
- spl_relocate_stack_gd() - Relocate stack ready for board_init_r() execution
- Sometimes board_init_f() runs with a stack in SRAM but we want to use SDRAM
- for the main board_init_r() execution. This is typically because we need
- more stack space for things like the MMC sub-system.
- This function calculates the stack position, copies the global_data into
- place and returns the new stack position. The caller is responsible for
- setting up the sp register.
- @return new stack location, or 0 to use the same stack
- */
+ulong spl_relocate_stack_gd(void) +{ +#ifdef CONFIG_SPL_STACK_R
- gd_t *new_gd;
- ulong ptr;
- /* Get stack position: use 8-byte alignment for ABI compliance */
- ptr = CONFIG_SPL_STACK_R - sizeof(gd_t);
- ptr &= ~7;
- new_gd = (gd_t *)ptr;
- memcpy(new_gd, (void *)gd, sizeof(gd_t));
- gd = new_gd;
- /* Clear the BSS. */
- memset(__bss_start, 0, __bss_end - __bss_start);
- return ptr;
+#else
- return 0;
+#endif +} diff --git a/doc/README.SPL b/doc/README.SPL index 3ba313c..327d3e2 100644 --- a/doc/README.SPL +++ b/doc/README.SPL @@ -95,3 +95,45 @@ cflow will spit out a number of warnings as it does not parse the config files and picks functions based on #ifdef. Parsing the '.i' files instead introduces another set of headaches. These warnings are not usually important to understanding the flow, however.
+ARM SPL Control Flow +--------------------
+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 aspl_board_init() function containing this call
- loads U-Boot or (in falcon mode) Linux
Reviewed-by: Stefano Babic sbabic@denx.de
Regards, Stefano