[PATCH v3 1/2] riscv: Add stimecmp save and restore

[Anup Patel]

On Mon, Oct 28, 2024 at 9:09 AM Nick Hu <nick.hu at sifive.com> wrote:
>
> If the HW support the SSTC extension, we should save and restore the
> stimecmp register while cpu non retention suspend.
>
> Signed-off-by: Nick Hu <nick.hu at sifive.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup

> ---
>  arch/riscv/include/asm/suspend.h |  4 ++++
>  arch/riscv/kernel/suspend.c      | 14 ++++++++++++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
> index 4ffb022b097f..dc5782b5fbad 100644
> --- a/arch/riscv/include/asm/suspend.h
> +++ b/arch/riscv/include/asm/suspend.h
> @@ -18,6 +18,10 @@ struct suspend_context {
>         unsigned long ie;
>  #ifdef CONFIG_MMU
>         unsigned long satp;
> +       unsigned long stimecmp;
> +#if __riscv_xlen < 64
> +       unsigned long stimecmph;
> +#endif
>  #endif
>  };
>
> diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
> index 9a8a0dc035b2..24b3f57d467f 100644
> --- a/arch/riscv/kernel/suspend.c
> +++ b/arch/riscv/kernel/suspend.c
> @@ -30,6 +30,13 @@ void suspend_save_csrs(struct suspend_context *context)
>          */
>
>  #ifdef CONFIG_MMU
> +       if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC)) {
> +               context->stimecmp = csr_read(CSR_STIMECMP);
> +#if __riscv_xlen < 64
> +               context->stimecmph = csr_read(CSR_STIMECMPH);
> +#endif
> +       }
> +
>         context->satp = csr_read(CSR_SATP);
>  #endif
>  }
> @@ -43,6 +50,13 @@ void suspend_restore_csrs(struct suspend_context *context)
>         csr_write(CSR_IE, context->ie);
>
>  #ifdef CONFIG_MMU
> +       if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC)) {
> +               csr_write(CSR_STIMECMP, context->stimecmp);
> +#if __riscv_xlen < 64
> +               csr_write(CSR_STIMECMPH, context->stimecmph);
> +#endif
> +       }
> +
>         csr_write(CSR_SATP, context->satp);
>  #endif
>  }
> --
> 2.34.1
>
>