APPLIED: ACK: [linux-riscv][J][PATCH] RISC-V: Use SBI SRST extension when available

[Dimitri John Ledkov]

Applied to linux-riscv Jammy.

Bug-Link: https://bugs.launchpad.net/bugs/1955042

-- 
Regards,

Dimitri.

On Mon, Feb 28, 2022 at 1:10 PM Tim Gardner <tim.gardner at canonical.com> wrote:
>
> Acked-by: Tim Gardner <tim.gardner at canonical.com>
>
> On 2/25/22 13:26, Dimitri John Ledkov wrote:
> > From: Anup Patel <anup.patel at wdc.com>
> >
> > The SBI SRST extension provides a standard way to poweroff and
> > reboot the system irrespective to whether Linux RISC-V S-mode
> > is running natively (HS-mode) or inside Guest/VM (VS-mode).
> >
> > The SBI SRST extension is available in the SBI v0.3 specification.
> > (Refer, https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0-rc1)
> >
> > This patch extends Linux RISC-V SBI implementation to detect
> > and use SBI SRST extension.
> >
> > Signed-off-by: Anup Patel <anup.patel at wdc.com>
> > Reviewed-by: Atish Patra <atish.patra at wdc.com>
> > Signed-off-by: Palmer Dabbelt <palmer at rivosinc.com>
> > (cherry picked from commit b579dfe71a6a5c3967ca9ad648673b6ca10ab0d5)
> > Bug-Link: https://bugs.launchpad.net/bugs/1955042
> > Signed-off-by: Dimitri John Ledkov <dimitri.ledkov at canonical.com>
> > ---
> >
> >   Test built and booted on unmatched board, and observed that poweroff
> >   is supported and works correctly via SBI SRST instead of
> >   gpio-poweroff. This is preffered, as in the future SBI SRST will the
> >   more universal way to poweroff and reboot.
> >
> >   arch/riscv/include/asm/sbi.h | 24 ++++++++++++++++++++++++
> >   arch/riscv/kernel/sbi.c      | 35 +++++++++++++++++++++++++++++++++++
> >   2 files changed, 59 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 0d42693cb6..289621da4a 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -27,6 +27,7 @@ enum sbi_ext_id {
> >       SBI_EXT_IPI = 0x735049,
> >       SBI_EXT_RFENCE = 0x52464E43,
> >       SBI_EXT_HSM = 0x48534D,
> > +     SBI_EXT_SRST = 0x53525354,
> >   };
> >
> >   enum sbi_ext_base_fid {
> > @@ -70,6 +71,21 @@ enum sbi_hsm_hart_status {
> >       SBI_HSM_HART_STATUS_STOP_PENDING,
> >   };
> >
> > +enum sbi_ext_srst_fid {
> > +     SBI_EXT_SRST_RESET = 0,
> > +};
> > +
> > +enum sbi_srst_reset_type {
> > +     SBI_SRST_RESET_TYPE_SHUTDOWN = 0,
> > +     SBI_SRST_RESET_TYPE_COLD_REBOOT,
> > +     SBI_SRST_RESET_TYPE_WARM_REBOOT,
> > +};
> > +
> > +enum sbi_srst_reset_reason {
> > +     SBI_SRST_RESET_REASON_NONE = 0,
> > +     SBI_SRST_RESET_REASON_SYS_FAILURE,
> > +};
> > +
> >   #define SBI_SPEC_VERSION_DEFAULT    0x1
> >   #define SBI_SPEC_VERSION_MAJOR_SHIFT        24
> >   #define SBI_SPEC_VERSION_MAJOR_MASK 0x7f
> > @@ -148,6 +164,14 @@ static inline unsigned long sbi_minor_version(void)
> >       return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK;
> >   }
> >
> > +/* Make SBI version */
> > +static inline unsigned long sbi_mk_version(unsigned long major,
> > +                                         unsigned long minor)
> > +{
> > +     return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
> > +             SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
> > +}
> > +
> >   int sbi_err_map_linux_errno(int err);
> >   #else /* CONFIG_RISCV_SBI */
> >   static inline int sbi_remote_fence_i(const unsigned long *hart_mask) { return -1; }
> > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> > index 7402a417f3..9a84f0cb51 100644
> > --- a/arch/riscv/kernel/sbi.c
> > +++ b/arch/riscv/kernel/sbi.c
> > @@ -7,6 +7,7 @@
> >
> >   #include <linux/init.h>
> >   #include <linux/pm.h>
> > +#include <linux/reboot.h>
> >   #include <asm/sbi.h>
> >   #include <asm/smp.h>
> >
> > @@ -501,6 +502,32 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask,
> >   }
> >   EXPORT_SYMBOL(sbi_remote_hfence_vvma_asid);
> >
> > +static void sbi_srst_reset(unsigned long type, unsigned long reason)
> > +{
> > +     sbi_ecall(SBI_EXT_SRST, SBI_EXT_SRST_RESET, type, reason,
> > +               0, 0, 0, 0);
> > +     pr_warn("%s: type=0x%lx reason=0x%lx failed\n",
> > +             __func__, type, reason);
> > +}
> > +
> > +static int sbi_srst_reboot(struct notifier_block *this,
> > +                        unsigned long mode, void *cmd)
> > +{
> > +     sbi_srst_reset((mode == REBOOT_WARM || mode == REBOOT_SOFT) ?
> > +                    SBI_SRST_RESET_TYPE_WARM_REBOOT :
> > +                    SBI_SRST_RESET_TYPE_COLD_REBOOT,
> > +                    SBI_SRST_RESET_REASON_NONE);
> > +     return NOTIFY_DONE;
> > +}
> > +
> > +static struct notifier_block sbi_srst_reboot_nb;
> > +
> > +static void sbi_srst_power_off(void)
> > +{
> > +     sbi_srst_reset(SBI_SRST_RESET_TYPE_SHUTDOWN,
> > +                    SBI_SRST_RESET_REASON_NONE);
> > +}
> > +
> >   /**
> >    * sbi_probe_extension() - Check if an SBI extension ID is supported or not.
> >    * @extid: The extension ID to be probed.
> > @@ -608,6 +635,14 @@ void __init sbi_init(void)
> >               } else {
> >                       __sbi_rfence    = __sbi_rfence_v01;
> >               }
> > +             if ((sbi_spec_version >= sbi_mk_version(0, 3)) &&
> > +                 (sbi_probe_extension(SBI_EXT_SRST) > 0)) {
> > +                     pr_info("SBI SRST extension detected\n");
> > +                     pm_power_off = sbi_srst_power_off;
> > +                     sbi_srst_reboot_nb.notifier_call = sbi_srst_reboot;
> > +                     sbi_srst_reboot_nb.priority = 192;
> > +                     register_restart_handler(&sbi_srst_reboot_nb);
> > +             }
> >       } else {
> >               __sbi_set_timer = __sbi_set_timer_v01;
> >               __sbi_send_ipi  = __sbi_send_ipi_v01;
>
> --
> -----------
> Tim Gardner
> Canonical, Inc