On Fri, 22 Jan 2021 at 20:48, Luc Michel <l...@lmichel.fr> wrote:
>
> On 19:06 Thu 21 Jan , Peter Maydell wrote:
> > Switch the CMSDK APB dualtimer device over to using its Clock input;
> > the pclk-frq property is now ignored.
> >
> > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> > ---
> > hw/timer/cmsdk-apb-dualtimer.c | 42 ++++++++++++++++++++++++++++++----
> > 1 file changed, 37 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/timer/cmsdk-apb-dualtimer.c b/hw/timer/cmsdk-apb-dualtimer.c
> > index 781b496037b..828127b366f 100644
> > --- a/hw/timer/cmsdk-apb-dualtimer.c
> > +++ b/hw/timer/cmsdk-apb-dualtimer.c
> > @@ -106,6 +106,22 @@ static void
> > cmsdk_apb_dualtimer_update(CMSDKAPBDualTimer *s)
> > qemu_set_irq(s->timerintc, timintc);
> > }
> >
> > +static int cmsdk_dualtimermod_divisor(CMSDKAPBDualTimerModule *m)
> > +{
> > + /* Return the divisor set by the current CONTROL.PRESCALE value */
> > + switch (FIELD_EX32(m->control, CONTROL, PRESCALE)) {
> > + case 0:
> > + return 1;
> > + case 1:
> > + return 16;
> > + case 2:
> > + case 3: /* UNDEFINED, we treat like 2 (and complained when it was set)
> > */
> > + return 256;
> > + default:
> > + g_assert_not_reached();
> > + }
> > +}
> > +
> > static void cmsdk_dualtimermod_write_control(CMSDKAPBDualTimerModule *m,
> > uint32_t newctrl)
> > {
> > @@ -146,7 +162,7 @@ static void
> > cmsdk_dualtimermod_write_control(CMSDKAPBDualTimerModule *m,
> > default:
> > g_assert_not_reached();
> > }
> > - ptimer_set_freq(m->timer, m->parent->pclk_frq / divisor);
> > + ptimer_set_period_from_clock(m->timer, m->parent->timclk, divisor);
>
> Just a small cosmetic note, maybe you can use your new
> cmsdk_dualtimermod_divisor function to factor out the switch above?
> Something like:
>
> if (changed & R_CONTROL_PRESCALE_MASK) {
> if (FIELD_EX32(newctrl, CONTROL, PRESCALE) == 3) {
> qemu_log_mask(LOG_GUEST_ERROR,
> "CMSDK APB dual-timer: CONTROL.PRESCALE==0b11"
> " is undefined behaviour\n");
> }
>
> ptimer_set_period_from_clock(m->timer, m->parent->timclk,
> cmsdk_dualtimermod_divisor(m));
> }
Nope, because cmsdk_dualtimermod_divisor() uses the current
m->control value, and at this point in the code we need the
divisor from the new control value which isn't in m->control yet.
I liked the slight duplication better than either having to
pass m->control in in all the other callsites or trying to
refactor the control write handling so that m->control is
updated before this point in the code.
thanks
-- PMM
