[PATCH 2/4] lib: sbi: Detect menvcfg CSR at boot time

[Xiang W]

在 2022-03-29星期二的 21:22 +0530，Anup Patel写道：
> From: Atish Patra <atishp at rivosinc.com>
> 
> We add the menvcfg CSR as a HART feature and detect it at boot time
> using traping mechanism.
> 
> Signed-off-by: Atish Patra <atishp at rivosinc.com>
> Signed-off-by: Anup Patel <apatel at ventanamicro.com>
Reviewed-by: Xiang W <wxjstz at 126.com>

Regards,
Xiang W
> ---
>  include/sbi/sbi_hart.h | 4 +++-
>  lib/sbi/sbi_hart.c     | 9 +++++++++
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index a83b45b..57f80bc 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -26,9 +26,11 @@ enum sbi_hart_features {
>         SBI_HART_HAS_TIME = (1 << 4),
>         /** HART has AIA local interrupt CSRs */
>         SBI_HART_HAS_AIA = (1 << 5),
> +       /** HART has menvcfg CSR */
> +       SBI_HART_HAS_MENVCFG = (1 << 6),
>  
>         /** Last index of Hart features*/
> -       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_AIA,
> +       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_MENVCFG,
>  };
>  
>  struct sbi_scratch;
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index e028540..31c8f39 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -304,6 +304,9 @@ static inline char
> *sbi_hart_feature_id2string(unsigned long feature)
>         case SBI_HART_HAS_AIA:
>                 fstr = "aia";
>                 break;
> +       case SBI_HART_HAS_MENVCFG:
> +               fstr = "menvcfg";
> +               break;
>         default:
>                 break;
>         }
> @@ -534,6 +537,12 @@ __mhpm_skip:
>                 goto __aia_skip;
>         hfeatures->features |= SBI_HART_HAS_AIA;
>  __aia_skip:
> +
> +       /* Detect if hart has menvcfg CSR */
> +       csr_read_allowed(CSR_MENVCFG, (unsigned long)&trap);
> +       if (!trap.cause)
> +               hfeatures->features |= SBI_HART_HAS_MENVCFG;
> +
>         return;
>  }
>  
> -- 
> 2.25.1
> 
>