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

[Alexandre Ghiti]

I chose a priority lower than the one you proposed in your SRST series
(https://lkml.org/lkml/2021/6/9/620).

Alex

On Tue, Sep 21, 2021 at 12:17 PM Anup Patel <anup at brainfault.org> wrote:
>
> On Tue, Sep 21, 2021 at 11:04 AM Alexandre Ghiti
> <alexandre.ghiti at canonical.com> wrote:
> >
> > The SiFive Unmatched board uses the da9063 PMIC for reset: add a restart
> > notifier that will execute a small i2c sequence allowing to reset the
> > board.
> >
> > The original implementation comes from Marcus Comstedt and Anders Montonen
> > (https://forums.sifive.com/t/reboot-command/4721/28).
> >
> > Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
> > ---
> >  drivers/mfd/da9063-core.c       | 25 +++++++++++++++++++++++++
> >  include/linux/mfd/da9063/core.h |  3 +++
> >  2 files changed, 28 insertions(+)
> >
> > diff --git a/drivers/mfd/da9063-core.c b/drivers/mfd/da9063-core.c
> > index df407c3afce3..c87b8d611f20 100644
> > --- a/drivers/mfd/da9063-core.c
> > +++ b/drivers/mfd/da9063-core.c
> > @@ -20,6 +20,7 @@
> >  #include <linux/mutex.h>
> >  #include <linux/mfd/core.h>
> >  #include <linux/regmap.h>
> > +#include <linux/reboot.h>
> >
> >  #include <linux/mfd/da9063/core.h>
> >  #include <linux/mfd/da9063/registers.h>
> > @@ -158,6 +159,18 @@ static int da9063_clear_fault_log(struct da9063 *da9063)
> >         return ret;
> >  }
> >
> > +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;
> > +}
> > +
> >  int da9063_device_init(struct da9063 *da9063, unsigned int irq)
> >  {
> >         int ret;
> > @@ -197,6 +210,18 @@ int da9063_device_init(struct da9063 *da9063, unsigned int irq)
> >                 }
> >         }
> >
> > +       da9063->restart_handler.notifier_call = da9063_restart_notify;
> > +       da9063->restart_handler.priority = 128;
>
> How was this priority value chosen ?
>
> I mean, we will be having SBI SRST as well so we should choose
> a priority value lower than what we choose for SBI SRST handler.
>
> Regards,
> Anup
>
> > +       ret = register_restart_handler(&da9063->restart_handler);
> > +       if (ret) {
> > +               dev_err(da9063->dev, "Failed to register restart handler\n");
> > +               return ret;
> > +       }
> > +
> > +       devm_add_action(da9063->dev,
> > +                       (void (*)(void *))unregister_restart_handler,
> > +                       &da9063->restart_handler);
> > +
> >         return ret;
> >  }
> >
> > diff --git a/include/linux/mfd/da9063/core.h b/include/linux/mfd/da9063/core.h
> > index fa7a43f02f27..1b20c498e340 100644
> > --- a/include/linux/mfd/da9063/core.h
> > +++ b/include/linux/mfd/da9063/core.h
> > @@ -85,6 +85,9 @@ struct da9063 {
> >         int             chip_irq;
> >         unsigned int    irq_base;
> >         struct regmap_irq_chip_data *regmap_irq;
> > +
> > +       /* Restart */
> > +       struct notifier_block restart_handler;
> >  };
> >
> >  int da9063_device_init(struct da9063 *da9063, unsigned int irq);
> > --
> > 2.30.2
> >