[PATCH v2] riscv: suspend: Add syscore ops for suspend

[Nick Hu]

Hi Anup


On Tue, Aug 22, 2023 at 2:16 PM Anup Patel <anup at brainfault.org> wrote:
>
> On Tue, Aug 22, 2023 at 11:17 AM Nick Hu <nick.hu at sifive.com> wrote:
> >
> > If a task is the one who performs the suspend flow and it also do some
> > floating or vector operations before the suspend, we might lose the FPU
> > and vector states when it goes to the non-retention system suspend state.
> > Add syscore ops to save and restore the FPU and vector states of the
> > current task to fix the issue above.
>
> This only applies to non-retentive system suspend so why do we need
> this before SBI system suspend is merged ?
>
> Regards,
> Anup
>
>
How about hibernation?

Regards,
Nick
> >
> > Co-developed-by: Andy Chiu <andy.chiu at sifive.com>
> > Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
> > Signed-off-by: Nick Hu <nick.hu at sifive.com>
> > ---
> > Changes in v2:
> > a) Add Co-developed-by and adjust the order of signed-off
> > b) Rephrase the commit message
> >
> >  arch/riscv/kernel/suspend.c | 45 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 45 insertions(+)
> >
> > diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
> > index 3c89b8ec69c4..ff69ff8a1974 100644
> > --- a/arch/riscv/kernel/suspend.c
> > +++ b/arch/riscv/kernel/suspend.c
> > @@ -4,9 +4,14 @@
> >   * Copyright (c) 2022 Ventana Micro Systems Inc.
> >   */
> >
> > +#include <linux/cpu_pm.h>
> >  #include <linux/ftrace.h>
> > +#include <linux/thread_info.h>
> > +#include <linux/syscore_ops.h>
> >  #include <asm/csr.h>
> >  #include <asm/suspend.h>
> > +#include <asm/switch_to.h>
> > +#include <asm/vector.h>
> >
> >  void suspend_save_csrs(struct suspend_context *context)
> >  {
> > @@ -85,3 +90,43 @@ int cpu_suspend(unsigned long arg,
> >
> >         return rc;
> >  }
> > +
> > +static int riscv_cpu_suspend(void)
> > +{
> > +       struct task_struct *cur_task = get_current();
> > +       struct pt_regs *regs = task_pt_regs(cur_task);
> > +
> > +       if (has_fpu()) {
> > +               if (unlikely(regs->status & SR_SD))
> > +                       fstate_save(cur_task, regs);
> > +       }
> > +       if (has_vector()) {
> > +               if (unlikely(regs->status & SR_SD))
> > +                       riscv_v_vstate_save(cur_task, regs);
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static void riscv_cpu_resume(void)
> > +{
> > +       struct task_struct *cur_task = get_current();
> > +       struct pt_regs *regs = task_pt_regs(cur_task);
> > +
> > +       if (has_fpu())
> > +               fstate_restore(cur_task, regs);
> > +       if (has_vector())
> > +               riscv_v_vstate_restore(cur_task, regs);
> > +}
> > +
> > +static struct syscore_ops riscv_cpu_syscore_ops = {
> > +       .suspend        = riscv_cpu_suspend,
> > +       .resume         = riscv_cpu_resume,
> > +};
> > +
> > +static int __init riscv_cpu_suspend_init(void)
> > +{
> > +       register_syscore_ops(&riscv_cpu_syscore_ops);
> > +       return 0;
> > +}
> > +arch_initcall(riscv_cpu_suspend_init);
> > --
> > 2.34.1
> >