[U-Boot] [PATCH 09/11] Exynos542x: Fix secondary core booting for thumb

[Simon Glass]

On 15 January 2015 at 06:42, Akshay Saraswat <akshay.s at samsung.com> wrote:
> When compiled SPL for Thumb secondary cores failed to boot
> at the kernel boot up. Only one core came up out of 4.
> This was happening because the code relocated to the
> address 0x02073000 by the primary core was an ARM asm
> code which was executed by the secondary cores as if it
> was a thumb code.
> This patch fixes the issue of secondary cores considering
> relocated code as Thumb instructions and not ARM instructions
> by jumping to the relocated with the help of "bx" ARM instruction.
> "bx" instruction changes the 5th bit of CPSR which allows
> execution unit to consider the following instructions as ARM
> instructions.
>
> Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
> ---
>  arch/arm/cpu/armv7/exynos/lowlevel_init.c | 2 +-
>  arch/arm/include/asm/arch-exynos/system.h | 3 +++
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c b/arch/arm/cpu/armv7/exynos/lowlevel_init.c
> index 57b4c66..d9f3f4b 100644
> --- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c
> +++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c
> @@ -110,7 +110,7 @@ static void secondary_cpu_start(void)
>  {
>         enable_smp();
>         svc32_mode_en();
> -       set_pc(CONFIG_EXYNOS_RELOCATE_CODE_BASE);
> +       branch_bx(CONFIG_EXYNOS_RELOCATE_CODE_BASE);
>  }
>
>  /*
> diff --git a/arch/arm/include/asm/arch-exynos/system.h b/arch/arm/include/asm/arch-exynos/system.h
> index 86903c3..a9fd5e6 100644
> --- a/arch/arm/include/asm/arch-exynos/system.h
> +++ b/arch/arm/include/asm/arch-exynos/system.h
> @@ -75,6 +75,9 @@ struct exynos5_sysreg {
>  /* Set program counter with the given value */
>  #define set_pc(x) __asm__ __volatile__ ("mov     pc, %0\n\t" : : "r"(x))
>
> +/* Branch to the given location */
> +#define branch_bx(x) __asm__ __volatile__ ("bx %0\n\t" : : "r"(x))
> +
>  /* Read Main Id register */
>  #define mrc_midr(x) __asm__ __volatile__       \
>                         ("mrc     p15, 0, %0, c0, c0, 0\n\t" : "=r"(x) : )
> --
> 1.9.1
>

Reviewed-by: Simon Glass <sjg at chromium.org>

Tested on snow, pit, pi
Tested-by: Simon Glass <sjg at chromium.org>