[RFC PATCH v6 1/2] arch: riscv: cpu: Add callback to init each core

[Rick Chen]

> From: Green Wan [mailto:green.wan at sifive.com]
> Sent: Thursday, April 15, 2021 4:45 PM
> Cc: Green Wan; Rick Jian-Zhi Chen(陳建志); Sean Anderson; Bin Meng; Simon Glass; Pragnesh Patel; Jagan Teki; Atish Patra; Leo Yu-Chi Liang(梁育齊); Brad Kim; u-boot at lists.denx.de
> Subject: [RFC PATCH v6 1/2] arch: riscv: cpu: Add callback to init each core

nitpicky, arch is redundant in title.

riscv: cpu: Add callback to init each core
will be fine.

>
> Add a callback harts_early_init() to start.S to allow different riscv
> hart perform setup code for each hart as early as possible. Since all
> the harts enter the callback, they must be able to run the same
> setup.
>
> Signed-off-by: Green Wan <green.wan at sifive.com>
> ---
>  arch/riscv/cpu/cpu.c   | 11 +++++++++++
>  arch/riscv/cpu/start.S |  8 ++++++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/arch/riscv/cpu/cpu.c b/arch/riscv/cpu/cpu.c
> index 85592f5bee..43c086ca19 100644
> --- a/arch/riscv/cpu/cpu.c
> +++ b/arch/riscv/cpu/cpu.c
> @@ -140,3 +140,14 @@ int arch_early_init_r(void)
>  {
>         return riscv_cpu_probe();
>  }
> +
> +/**
> + * harts_early_init() - A callback function called by start.S to configure
> + * feature settings of each hart.
> + *
> + * In a multi-core system, memory access shall be careful here, it shall
> + * take care race conditions.
> + */
> +__weak void harts_early_init(void)
> +{
> +}
> diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
> index 8589509e01..42fc1a4406 100644
> --- a/arch/riscv/cpu/start.S
> +++ b/arch/riscv/cpu/start.S
> @@ -117,6 +117,14 @@ call_board_init_f_0:
>         mv      sp, a0
>  #endif
>
> +#if CONFIG_IS_ENABLED(RISCV_MMODE)

This M-mode check can be remove, it is a repeat confirmation in
harts_early_init() of arch/riscv/cpu/fu740/spl.c

Other than that,

Reviewed-by: Rick Chen <rick at andestech.com>

> +       /*
> +        * Configure proprietary settings and customized CRSs of harts
> +        */
> +call_harts_early_init:
> +       jal     harts_early_init
> +#endif
> +
>  #ifndef CONFIG_XIP
>         /*
>          * Pick hart to initialize global data and run U-Boot. The other harts
> --
> 2.31.0