[PATCH 1/3] MIPS: pbl: add pbl_blt macro

[Yegor Yefremov]

On Wed, Nov 11, 2015 at 2:09 AM, Antony Pavlov <antonynpavlov at gmail.com> wrote:
> From: Oleksij Rempel <linux at rempel-privat.de>
>
> Barebox' PBL can initialize memory controller of the board.
> But we can use memory controller initialization routine
> only if PBL runs from ROM or on-chip SRAM.
> MIPS architecture standard boot vector is 0xbfc00000
> so on most MIPS SoCs all addresses higher than 0xbfc00000
> belong to boot ROM or on-chip SRAM. Well then we have
> simple criterion to check if PBL run from ROM: just
> check if current PC is higher than 0xbfc00000.
> Some MIPS boards have ROM start address lower than 0xbfc00000
> so it's reasonable we have to make ROM start address
> board dependend.
>
> The pbl_blt macro checks if current pc is lower than
> the first argument (ROM start address). If so then
> next instruction executed is defined by the second argument
> of the macro.
>
> Signed-off-by: Oleksij Rempel <linux at rempel-privat.de>
> Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
> ---
>  arch/mips/include/asm/pbl_macros.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/arch/mips/include/asm/pbl_macros.h b/arch/mips/include/asm/pbl_macros.h
> index c4ae6a2..dbe3410 100644
> --- a/arch/mips/include/asm/pbl_macros.h
> +++ b/arch/mips/include/asm/pbl_macros.h
> @@ -60,6 +60,18 @@
>         .set    pop
>         .endm
>
> +       .macro  pbl_blt addr label tmp
> +       .set    push
> +       .set    noreorder
> +       move    \tmp, ra                        # preserve ra beforehand
> +       bal     253f
> +        nop
> +253:
> +       bltu    ra, \addr, \label
> +        move   ra, \tmp                        # restore ra
> +       .set    pop
> +       .endm
> +
>         .macro  pbl_sleep reg count
>         .set push
>         .set noreorder
> --
> 2.6.2

Loaded barebox.bin via OpenOCD and successfully started

Tested-by: Yegor Yefremov <yegorslists at googlemail.com>

Yegor