[RFC PATCH 1/1] lib: sbi_timer: Added a blocking wait function that waits until a certain condition is true or timeout occurs

[Adnan Chowdhury]

Thank you Xiang.

On Wed, Jun 29, 2022 at 3:58 PM Xiang W <wxjstz at 126.com> wrote:
>
> 在 2022-06-29星期三的 14:42 +0100，Adnan Rahman Chowdhury写道：
> > Motivation: Suppose a peripheral needs to be configured to transmit data.
> > There is an SFR bit which indicates that the peripheral is ready to transmit.
> > The firmware should check the bit and will only transmit data when the
> > peripheral is ready. When the firmware starts polling the SFR, the peripheral
> > could be busy transmitting/receiving other data so the firmware must wait
> > till that completes. Assuming that there is no other way, the
> > firmware shouldn't wait indefinitely.
> >
> > The function sbi_timer_waitms_until() will constantly check whether a certain
> > condition is met, or timeout occurs. It can be used for the cases when a
> > timeout is required.
> >
> > Signed-off-by: Adnan Rahman Chowdhury <adnan.chowdhury at sifive.com>
> LGTM
>
> Reviewed-by: Xiang W <wxjstz at 126.com>
> > ---
> >  include/sbi/sbi_timer.h |  3 +++
> >  lib/sbi/sbi_timer.c     | 18 ++++++++++++++++++
> >  2 files changed, 21 insertions(+)
> >
> > diff --git a/include/sbi/sbi_timer.h b/include/sbi/sbi_timer.h
> > index 63ef1af..ea3dbdd 100644
> > --- a/include/sbi/sbi_timer.h
> > +++ b/include/sbi/sbi_timer.h
> > @@ -48,6 +48,9 @@ static inline void sbi_timer_udelay(ulong usecs)
> >         sbi_timer_delay_loop(usecs, 1000000, NULL, NULL);
> >  }
> >
> > +bool sbi_timer_waitms_until(bool (*predicate)(void *), void *arg,
> > +                           uint64_t timeout_ms);
> > +
> >  /** Get timer value for current HART */
> >  u64 sbi_timer_value(void);
> >
> > diff --git a/lib/sbi/sbi_timer.c b/lib/sbi/sbi_timer.c
> > index acdba92..d93036d 100644
> > --- a/lib/sbi/sbi_timer.c
> > +++ b/lib/sbi/sbi_timer.c
> > @@ -81,6 +81,24 @@ void sbi_timer_delay_loop(ulong units, u64 unit_freq,
> >                 delay_fn(opaque);
> >  }
> >
> > +bool sbi_timer_waitms_until(bool(*predicate)(void*), void* arg,
> > +                           uint64_t timeout_ms)
> > +{
> > +       bool ret = true;
> > +       uint64_t start_time = sbi_timer_value();
> > +       uint64_t ticks =
> > +               (sbi_timer_get_device()->timer_freq / 1000) *
> > +               (timeout_ms);
> > +       do {
> > +               if (predicate(arg))
> > +                       break;
> > +               if (sbi_timer_value() - start_time  >= ticks)
> > +                       ret = false;
> > +       } while(ret);
> > +
> > +       return ret;
> > +}
> > +
> >  u64 sbi_timer_value(void)
> >  {
> >         if (get_time_val)
> > --
> > 2.30.2
> >
> >
>
>


-- 
Best Regards,
Adnan Rahman Chowdhury