[PATCH v3 5/5] lib: sbi: Implement System Reset (SRST) SBI extension

[Atish Patra]

On Tue, Nov 24, 2020 at 9:17 PM Anup Patel <anup.patel at wdc.com> wrote:
>
> The SBI SRST extension has been accepted and merged in the latest
> SBI v0.3-draft specification.
> (Refer, https://github.com/riscv/riscv-sbi-doc)
>
> It allows to S-mode software to request system shutdown, cold reboot,
> and warm reboot.
>
> This patch implements SBI SRST extension as a replacement of the
> legacy sbi_shutdown() call of SBI v0.1 specification.
>
> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> ---
>  include/sbi/sbi_ecall.h     |  1 +
>  lib/sbi/sbi_ecall.c         |  3 ++
>  lib/sbi/sbi_ecall_replace.c | 60 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 64 insertions(+)
>
> diff --git a/include/sbi/sbi_ecall.h b/include/sbi/sbi_ecall.h
> index 3273ba6..1ef86e2 100644
> --- a/include/sbi/sbi_ecall.h
> +++ b/include/sbi/sbi_ecall.h
> @@ -37,6 +37,7 @@ extern struct sbi_ecall_extension ecall_rfence;
>  extern struct sbi_ecall_extension ecall_ipi;
>  extern struct sbi_ecall_extension ecall_vendor;
>  extern struct sbi_ecall_extension ecall_hsm;
> +extern struct sbi_ecall_extension ecall_srst;
>
>  u16 sbi_ecall_version_major(void);
>
> diff --git a/lib/sbi/sbi_ecall.c b/lib/sbi/sbi_ecall.c
> index 64c9933..6d41cff 100644
> --- a/lib/sbi/sbi_ecall.c
> +++ b/lib/sbi/sbi_ecall.c
> @@ -167,6 +167,9 @@ int sbi_ecall_init(void)
>         if (ret)
>                 return ret;
>         ret = sbi_ecall_register_extension(&ecall_hsm);
> +       if (ret)
> +               return ret;
> +       ret = sbi_ecall_register_extension(&ecall_srst);
>         if (ret)
>                 return ret;
>         ret = sbi_ecall_register_extension(&ecall_legacy);
> diff --git a/lib/sbi/sbi_ecall_replace.c b/lib/sbi/sbi_ecall_replace.c
> index e460c30..d06dfa2 100644
> --- a/lib/sbi/sbi_ecall_replace.c
> +++ b/lib/sbi/sbi_ecall_replace.c
> @@ -14,6 +14,7 @@
>  #include <sbi/sbi_error.h>
>  #include <sbi/sbi_hart.h>
>  #include <sbi/sbi_ipi.h>
> +#include <sbi/sbi_system.h>
>  #include <sbi/sbi_timer.h>
>  #include <sbi/sbi_tlb.h>
>
> @@ -127,3 +128,62 @@ struct sbi_ecall_extension ecall_ipi = {
>         .extid_end = SBI_EXT_IPI,
>         .handle = sbi_ecall_ipi_handler,
>  };
> +
> +static int sbi_ecall_srst_handler(unsigned long extid, unsigned long funcid,
> +                                 unsigned long *args, unsigned long *out_val,
> +                                 struct sbi_trap_info *out_trap)
> +{
> +       if (funcid == SBI_EXT_SRST_RESET) {
> +               if ((((u32)-1U) <= ((u64)args[0])) ||
> +                   (((u32)-1U) <= ((u64)args[1])))
> +                       return SBI_EINVAL;
> +
> +               switch (args[0]) {
> +               case SBI_SRST_RESET_TYPE_SHUTDOWN:
> +               case SBI_SRST_RESET_TYPE_COLD_REBOOT:
> +               case SBI_SRST_RESET_TYPE_WARM_REBOOT:
> +                       break;
> +               default:
> +                       return SBI_ENOTSUPP;
> +               }
> +
> +               switch (args[1]) {
> +               case SBI_SRST_RESET_REASON_NONE:
> +               case SBI_SRST_RESET_REASON_SYSFAIL:
> +                       break;
> +               default:
> +                       return SBI_ENOTSUPP;
> +               }
> +
> +               if (sbi_system_reset_supported(args[0], args[1]))
> +                       sbi_system_reset(args[0], args[1]);
> +       }
> +
> +       return SBI_ENOTSUPP;
> +}
> +
> +static int sbi_ecall_srst_probe(unsigned long extid, unsigned long *out_val)
> +{
> +       u32 type, count = 0;
> +
> +       /*
> +        * At least one standard reset types should be supported by
> +        * the platform for SBI SRST extension to be usable.
> +        */
> +
> +       for (type = 0; type <= SBI_SRST_RESET_TYPE_LAST; type++) {
> +               if (sbi_system_reset_supported(type,
> +                                       SBI_SRST_RESET_REASON_NONE))
> +                       count++;
> +       }
> +
> +       *out_val = (count) ? 1 : 0;
> +       return 0;
> +}
> +
> +struct sbi_ecall_extension ecall_srst = {
> +       .extid_start = SBI_EXT_SRST,
> +       .extid_end = SBI_EXT_SRST,
> +       .handle = sbi_ecall_srst_handler,
> +       .probe = sbi_ecall_srst_probe,
> +};
> --
> 2.25.1
>
>
> --
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Reviewed-by: Atish Patra <atish.patra at wdc.com>
-- 
Regards,
Atish