This is already set up in crt0.S. We don't need a new structure and don't really want one in the 'data' section of the image, since it will be empty and crt0.S's changes will be ignored.

As an interim measure, remove it only if CONFIG_DM is not defined. This allows us to press ahead with driver model in SPL and allow the stragglers to catch up.

Signed-off-by: Simon Glass sjg@chromium.org ---

Changes in v5: None Changes in v4: - Squash the gdata revert patch into this one - Allow gdata to survive unless CONFIG_DM is defined, for now

Changes in v3: None Changes in v2: - Remove gdata definition from ARM spl header file also

arch/arm/include/asm/spl.h | 2 ++ arch/arm/lib/spl.c | 4 ++++ 2 files changed, 6 insertions(+)

diff --git a/arch/arm/include/asm/spl.h b/arch/arm/include/asm/spl.h index 17b6f54..6db405d 100644 --- a/arch/arm/include/asm/spl.h +++ b/arch/arm/include/asm/spl.h @@ -37,6 +37,8 @@ void spl_board_load_image(void); /* Linker symbols. */ extern char __bss_start[], __bss_end[];

+#ifndef CONFIG_DM extern gd_t gdata; +#endif

#endif diff --git a/arch/arm/lib/spl.c b/arch/arm/lib/spl.c index c41850a..bd8c7d2 100644 --- a/arch/arm/lib/spl.c +++ b/arch/arm/lib/spl.c @@ -13,6 +13,7 @@ #include <image.h> #include <linux/compiler.h>

+#ifndef CONFIG_DM /* Pointer to as well as the global data structure for SPL */ DECLARE_GLOBAL_DATA_PTR;

@@ -21,6 +22,7 @@ DECLARE_GLOBAL_DATA_PTR; * pafches that rely on it. The global_data area is set up in crt0.S. */ gd_t gdata __attribute__ ((section(".data"))); +#endif

/* * In the context of SPL, board_init_f must ensure that any clocks/etc for @@ -33,8 +35,10 @@ void __weak board_init_f(ulong dummy) /* Clear the BSS. */ memset(__bss_start, 0, __bss_end - __bss_start);

+#ifndef CONFIG_DM /* TODO: Remove settings of the global data pointer here */ gd = &gdata; +#endif

board_init_r(NULL, 0); }

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 documented in the README.

Signed-off-by: Simon Glass sjg@chromium.org For version 1: Acked-by: Albert ARIBAUD albert.u.boot@aribaud.net Reviewed-by: Stefan Roese sr@denx.de Tested-by: Bo Shen voice.shen@atmel.com Acked-by: Bo Shen voice.shen@atmel.com Acked-by: Heiko Schocher hs@denx.de Tested-by: Heiko Schocher hs@denx.de ---

Changes in v5: - Rebase to master

Changes in v4: - Adjust README to mention that lowlevel_init() should have no stack

Changes in v3: None Changes in v2: - Move docs to top-level README file and expand them to cover U-Boot proper - Add Kconfig settings

Kconfig | 18 ++++++++++++++ README | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++ arch/arm/lib/crt0.S | 13 +++++++--- common/spl/spl.c | 35 +++++++++++++++++++++++++++ 4 files changed, 132 insertions(+), 3 deletions(-)

diff --git a/Kconfig b/Kconfig index 91a0618..8de731d 100644 --- a/Kconfig +++ b/Kconfig @@ -96,6 +96,24 @@ config SPL help If you want to build SPL as well as the normal image, say Y.

+config CONFIG_SPL_STACK_R + depends on SPL + bool "Enable SDRAM location for SPL stack" + help + SPL starts off execution in SRAM and thus typically has only a small + stack available. Since SPL sets up DRAM while in its board_init_f() + function, it is possible for the stack to move there before + board_init_r() is reached. This option enables a special SDRAM + location for the SPL stack. U-Boot SPL switches to this after + board_init_f() completes, and before board_init_r() starts. + +config CONFIG_SPL_STACK_R_ADDR + depends on CONFIG_SPL_STACK_R + hex "SDRAM location for SPL stack" + help + Specify the address in SDRAM for the SPL stack. This will be set up + before board_init_r() is called. + config TPL bool depends on SPL && SUPPORT_TPL diff --git a/README b/README index febefb5..3547ead 100644 --- a/README +++ b/README @@ -273,6 +273,75 @@ run some of U-Boot's tests. See board/sandbox/README.sandbox for more details.

+Board Initialisation Flow: +-------------------------- + +This is the intended start-up flow for boards. This should apply for both +SPL and U-Boot proper (i.e. they both follow the same rules). At present SPL +mostly uses a separate code path, but the funtion names and roles of each +function are the same. Some boards or architectures may not conform to this. +At least most ARM boards which use CONFIG_SPL_FRAMEWORK conform to this. + +Execution starts with start.S with three functions called during init after +that. The purpose and limitations of each is described below. + +lowlevel_init(): + - purpose: essential init to permit execution to reach board_init_f() + - no global_data or BSS + - there is no stack (ARMv7 may have one but it will soon be removed) + - 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 + - stack is in SRAM + - BSS is not available, so you cannot use global/static variables, + only stack variables and global_data + + Non-SPL-specific notes: + - dram_init() is called to set up DRAM. If already done in SPL this + can do nothing + + SPL-specific notes: + - you can override the entire board_init_f() function with your own + version as needed. + - preloader_console_init() can be called here in extremis + - 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. For SPL, if CONFIG_SPL_STACK_R is defined, then at +this point the stack and global_data are relocated to below +CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of +memory. + +board_init_r(): + - purpose: main execution, common code + - global_data is available + - SDRAM is available + - BSS is available, all static/global variables can be used + - execution eventually continues to main_loop() + + Non-SPL-specific notes: + - U-Boot is relocated to the top of memory and is now running from + there. + + SPL-specific notes: + - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and + CONFIG_SPL_STACK_R_ADDR 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 + + + Configuration Options: ----------------------

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 ded0f30..cd75bbc 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -281,3 +281,38 @@ 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 +}