[PATCH 3/7] riscv: Use NULL as a sentinel value for smp_call_function

[Bin Meng]

On Tue, Sep 8, 2020 at 2:17 AM Sean Anderson <seanga2 at gmail.com> wrote:
>
> Some IPIs may already be pending when U-Boot is started. This could be a
> problem if a secondary hart tries to handle an IPI before the boot hart has
> initialized the IPI device.
>
> This commit uses NULL as a sentinel for secondary harts so they know when
> the IPI is initialized, and it is safe to use the IPI API. The smp addr
> parameter is initialized to NULL by board_init_f_init_reserve. Before this,
> secondary harts wait in wait_for_gd_init.
>
> This imposes a minor restriction because harts may no longer jump to NULL.
> However, given that the RISC-V debug device is likely to be located at
> 0x400, it is unlikely for any RISC-V implementation to have usable ram
> located at 0x0.
>
> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
> ---
>
>  arch/riscv/lib/smp.c | 26 ++++++++++++++++++++++----
>  1 file changed, 22 insertions(+), 4 deletions(-)
>

Reviewed-by: Bin Meng <bin.meng at windriver.com>