[PATCH] drivers: mfd: da9063: Add restart notifier implementation

[Alexandre Ghiti]

On Thu, Sep 30, 2021 at 12:25 PM Alexandre Ghiti
<alexandre.ghiti at canonical.com> wrote:
>
> Hi David,
>
> On Thu, Sep 30, 2021 at 9:51 AM David Abdurachmanov
> <david.abdurachmanov at gmail.com> wrote:
> >
> > On Wed, Sep 29, 2021 at 4:36 PM Adam Thomson
> > <Adam.Thomson.Opensource at diasemi.com> wrote:
> > >
> > > On 24 September 2021 17:17, Alexandre Ghiti wrote:
> > >
> > > > > > +static int da9063_restart_notify(struct notifier_block *this,
> > > > > > +                              unsigned long mode, void *cmd)
> > > > > > +{
> > > > > > +     struct da9063 *da9063 = container_of(this, struct da9063,
> > > > > > restart_handler);
> > > > > > +
> > > > > > +     regmap_write(da9063->regmap, DA9063_REG_PAGE_CON, 0x00);
> > > > > > +     regmap_write(da9063->regmap, DA9063_REG_CONTROL_F, 0x04);
> > > > > > +     regmap_write(da9063->regmap, DA9063_REG_CONTROL_A, 0x68);
> > > > > > +
> > > > > > +     return NOTIFY_DONE;
> > > > > > +}
> > > > >
> > > > > I will talk with our HW team to clarify, but this sequence looks to be very
> > > > > specific to the needs of the platform in question which doesn't feel right to
> > > > > me. As was mentioned on another thread as well, the watchdog driver already
> > > > has
> > > > > a restart function to reset the device (and thus the system), so I don't believe
> > > > > we should have multiple of these.
> > > >
> > > > From the discussion that happened here
> > > > https://www.dialog-semiconductor.com/products/pmics?post_id=10052#tab-
> > > > support_tab_content,
> > > > it does not seem possible to use the watchdog on a chip whose OTP does
> > > > not set AUTOBOOT. But anyway, I'm looking forward to hearing from the
> > > > HW team :)
> > >
> > > So I've discussed this internally and so far it's not completely clear how the
> > > sequence you provided actually performs the reset as you suggest. It certainly
> > > doesn't look like it should, so maybe this relates to an external pin somehow
> > > triggering the restart in this particular scenario? I'd be interested to
> > > understand which event bits are set when the board does restart to understand
> > > what did actually trigger the boot-up.
> > >
> > > Regardless of this though, the consensus right now would be to use the RTC as a
> > > wake event to restart the platform. An alarm can be set for a couple of seconds
> > > into the future (or longer if required) and that would provide the event
> > > required to come up from powerdown/shutdown, in the absence of AUTOBOOT being
> > > set in OTP. I believe this would be the safest route to take in this case. You
> > > can then just use the SHUTDOWN bit on CONTROL_F to take down the board.
> >
> > Today I was looking into OpenBSD DA9063 drivers and they might be
> > doing what you described for the reset.
> >
> > dev/fdt/dapmic.c
> >
> > [..]
> > 241 void
> > 242 dapmic_reset(void)
> > 243 {
> > 244     struct dapmic_softc *sc = dapmic_cd.cd_devs[0];
> > 245     uint8_t reg;
> > 246
> > 247     /* Enable tick alarm wakeup with a one second interval. */
> > 248     reg = dapmic_reg_read(sc, ALARM_MO);
> > 249     reg &= ~ALARM_MO_TICK_TYPE;
> > 250     reg |= ALARM_MO_TICK_WAKE;
> > 251     dapmic_reg_write(sc, ALARM_MO, reg);
> > 252
> > 253     /* Enable tick function. */
> > 254     reg = dapmic_reg_read(sc, ALARM_Y);
> > 255     reg |= ALARM_Y_TICK_ON;
> > 256     dapmic_reg_write(sc, ALARM_Y, reg);
> > 257
> > 258     /* Clear events such that we wake up again. */
> > 259     dapmic_reg_write(sc, EVENT_A, dapmic_reg_read(sc, EVENT_A));
> > 260     dapmic_reg_write(sc, CONTROL_F, CONTROL_F_SHUTDOWN);
> > 261 }
> > [..]
> >
>
> Thanks for the pointer! I have just tested this sequence from the
> u-boot shell, it resets the board correctly. But then if we try to
> power down the board by a long press to the corresponding button on
> the board within 16 seconds, it resets the board: so we cannot
> shutdown the board in the next 16 seconds that follow this sequence.
>
> Maybe that can be resolved by using the one-shot alarm as described by
> Adam, I'll try to find that in the datasheet.

After configuring the one-shot alarm, I still have those intempestive
reboots if I try to power down the board by a long press within 16
seconds. The only thing I found in the datasheet regarding this timing
is in case of power undervoltage, not sure how this is linked to what
I see.

@Adam Thomson Any ideas?

Thanks,

Alex

>
> Thanks
>
> Alex
>
> > >
> > > To reiterate, I believe this should be made a board specific quirk, rather than
> > > as part of the generic MFD core of DA9063, as the timings may vary for other
> > > platforms.
> >
> > Agree. Currently it seems Linux drivers expect DA9063 boards to have
> > AUTOBOOT ON set in OTP, which is not the case for SiFive Unmatched
> > (thus issues with reset and WDT).
> >
> > david
> >
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