[U-Boot] SPL: branching out of start.S

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

---------------------------------------------------------------------------

> 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

On Wed, Nov 23, 2011 at 7:13 AM, Marek Vasut <marek.vasut@gmail.com> wrote:
>> Is it possible to merge things further and get rid of this special case?

I'd rather stick with the common code and not proliferate start.S
versions. The main bug right now is that r9 is not zero'd for the SPL
case causing a random offset to be added.

But more consolidation is possible:

	ldr	r0, _board_init_r_ofs	ldr	r1, _TEXT_BASE	add	lr, r0, r1	add	lr,
lr, r9	/* setup parameters for board_init_r */	mov	r0, r5		/* gd_t
*/	mov	r1, r6		/* dest_addr */	/* jump to it ... */	mov	pc, lr
_board_init_r_ofs:#ifdef CONFIG_NAND_SPL
	.word nand_boot - _start
#else
	.word board_init_r - _start#endif

Even more if nand_boot is wrapped and renamed board_init_r().