From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bo Shen Date: Wed, 21 Jan 2015 17:48:02 +0800 Subject: [U-Boot] [PATCH] arm: spl: Allow board_init_r() to run with a larger stack In-Reply-To: <1421607336-26934-1-git-send-email-sjg@chromium.org> References: <1421607336-26934-1-git-send-email-sjg@chromium.org> Message-ID: <54BF75D2.3090203@atmel.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Simon Glass, On 01/19/2015 02:55 AM, 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 Tested-by: Bo Shen Acked-by: Bo Shen > --- > > 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 a > + spl_board_init() function containing this call > + - loads U-Boot or (in falcon mode) Linux > Best Regards, Bo Shen