[U-Boot] SPL: branching out of start.S
Marek Vasut
marek.vasut at gmail.com
Wed Nov 23 13:13:16 CET 2011
> The way the SPL code is setup right now it only works in the
> CONFIG_NAND_SPL case. The chip I'm working on, the lpc313x, can SPL
> from six different sources. I've implemented the secondary loader code
> in board_init_r in cpu/arm926ejs/lpc313x/spl.c. I needed to modify
> start.S so that the jump to board_init_r works correctly in the SPL
> case.
>
> Is it possible to merge things further and get rid of this special case?
>
> #ifdef CONFIG_NAND_SPL
> ldr r0, _nand_boot_ofs
> mov pc, r0
>
> _nand_boot_ofs:
> .word nand_boot
> #else
> ldr r0, _board_init_r_ofs
> ldr r1, _TEXT_BASE
> add lr, r0, r1
> add lr, lr, r9
>
> ---------------------------------------------------------------------------
>
> diff --git a/arch/arm/cpu/arm926ejs/start.S
> b/arch/arm/cpu/arm926ejs/start.S index 5e30745..0f97979 100644
> --- a/arch/arm/cpu/arm926ejs/start.S
> +++ b/arch/arm/cpu/arm926ejs/start.S
> @@ -64,6 +64,13 @@ _start:
> b reset
> #endif
> #ifdef CONFIG_SPL_BUILD
> +#ifdef CONFIG_LPC313x_BOOT_HEADER
> + .word 0x41676d69 /* image magic number, imgA */
> + .word 0,0,0,0,0
> + .word 0x0000000A /*Plain text no CRC check*/
> + .word (__initial_boot_image_size) /* image length */
> + .word 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
> +#else
> /* No exception handlers in preloader */
> ldr pc, _hang
> ldr pc, _hang
> @@ -83,6 +90,7 @@ _hang:
> .word 0x12345678
> .word 0x12345678
> .word 0x12345678
> +#endif
> #else
> ldr pc, _undefined_instruction
> ldr pc, _software_interrupt
> @@ -126,7 +134,11 @@ _fiq:
>
> .globl _TEXT_BASE
> _TEXT_BASE:
> +#ifdef CONFIG_SPL_BUILD
> + .word CONFIG_SPL_TEXT_BASE
> +#else
> .word CONFIG_SYS_TEXT_BASE
> +#endif
>
> /*
> * These are defined in the board-specific linker script.
> @@ -210,6 +222,7 @@ relocate_code:
> stack_setup:
> mov sp, r4
>
> + mov r9, #0x00000000 /* relocation offset starts at zero
> */ adr r0, _start
> cmp r0, r6
> beq clear_bss /* skip relocation */
You can supply your own, separate, start.S for SPL.
M
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