[U-Boot] [PATCH v2 02/11] Exynos542x: CPU: Power down all secondary cores

[Simon Glass]

On 3 February 2015 at 01:18, Akshay Saraswat <akshay.s at samsung.com> wrote:
> This patch adds code to shutdown secondary cores.
> When U-boot comes up, all secondary cores appear powered on,
> which is undesirable and causes side effects while
> initializing these cores in kernel.
>
> Secondary core power down happens in following steps:
>
> Step-1: After Exynos power-on, primary core starts executing first.
> Step-2: In iROM code every core has to check 2 flags i.e.
>         addresses 0x02020028 & 0x02020004.
> Step-3: Initially 0x02020028 is 0 for all cores and 0x02020004 has a
>         jump address for primary core and 0 for all secondary cores.
> Step-4: Therefore, primary core follows normal iROM execution and jumps
>         to BL1 eventually, whereas all secondary cores enter WFE.
> Step-5: When primary core comes into function secondary_cores_configure,
>         it puts pointer to function power_down_core into 0x02020004
>         and provides DSB and SEV for all cores so that they may come out
>         of WFE and jump to power_down_core function.
> Step-6: And ultimately because of power_down_core all
>         secondary cores shut-down.
>
> Signed-off-by: Kimoon Kim <kimoon.kim at samsung.com>
> Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
> ---
> Changes since v1:
>         - Removed unnecessary macros.
>         - Changed names of few macros for better understanding.
>         - Added MPIDR bit assignment info comment in power_down_core.
>
>  arch/arm/cpu/armv7/exynos/exynos5_setup.h |  3 ++
>  arch/arm/cpu/armv7/exynos/lowlevel_init.c | 69 ++++++++++++++++++++++++
>  arch/arm/include/asm/arch-exynos/cpu.h    |  5 ++
>  arch/arm/include/asm/arch-exynos/system.h | 87 +++++++++++++++++++++++++++++++
>  4 files changed, 164 insertions(+)

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