[PATCH 0/3] ARM: bcm: Enable SMP on the Genexis XG6846B

[William Zhang]

Hi Linus,

On Mon, Oct 12, 2026 at 1:03 AM Linus Walleij <linusw at kernel.org> wrote:
>
> When booted through CFE and mainline U-Boot, the XG6846B has no PSCI
> provider. CFE powers up CPU1 and leaves it waiting in a holding pen.
>
> Preserve the holding pen, add a board-specific SMP method using CFE's
> GPIO mailbox and a wakeup IPI, and disable the inherited PSCI setup.
> Tested on the XG6846B with both CPUs coming online.
>
> Assisted-by: LLM
> Signed-off-by: Linus Walleij <linusw at kernel.org>
> ---
> Linus Walleij (3):
>       ARM: dts: broadcom: Preserve the XG6846B CFE holding pen
>       ARM: bcm: Add CFE SMP support for the Genexis XG6846B
>       ARM: dts: broadcom: Use CFE CPU bring-up on the XG6846B
>
>  .../boot/dts/broadcom/bcm6846-genexis-xg6846b.dts  | 15 +++++-
>  arch/arm/mach-bcm/Makefile                         |  2 +-
>  arch/arm/mach-bcm/board_bcmbca.c                   | 53 ++++++++++++++++++++++
>  3 files changed, 68 insertions(+), 2 deletions(-)
> ---
> base-commit: 6356fd3dd29d8b5620507a0ce037c644e052b5dd
> change-id: 20261011-genexis-xg6846-smp-v7-3-rc1-b470f0e20475
>
> Best regards,
> --
> Linus Walleij <linusw at kernel.org>
>

The change ties the implementation to a specific board and includes
GPIO register definitions in the c code.  I suggest we define these
through the dts itself so the code can be generic and apply to other
boards via the dts.

In Broadcom's reference design, we introduce an SMP method for this
GPIO-based smp boot up support:
    enable-method = "brcm,bca-smp"
and implement through the CPU_METHOD_OF_DECLARE(bcm_smp,
"brcm,bca-smp", &bcm_smp_ops). This way we don't have to check the
board id but automatically run the smp init code using dts
"brcm,bca-smp" method.

We can also define gpio register in the cpu node along with the
enable-method property
    cpu-release-addr = <0xFF800568>;

Thanks,
William
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