Re: [PATCH] mfd: tps65219: Add support for soft shutdown via sys-off API

[jerome Neanne]

On 01/03/2023 17:35, Andrew Davis wrote:
> On 3/1/23 10:07 AM, Lee Jones wrote:
> > On Fri, 03 Feb 2023, Jerome Neanne wrote:
> >
> > > Use new API for power-off mode support:
> > > Link: https://lwn.net/Articles/894511/
> > > Link: https://lore.kernel.org/all/7hfseqa7l0.fsf@xxxxxxxxxxxx/
> > >
> > > sys-off API allows support of shutdown handler and restart handler.
> > >
> > > Shutdown was not supported before that enhancement.
> > > This is required for platform that are not using PSCI.
>
> Not sure what platform doesn't have PSCI off, since you tested on
> AM62-SK I'm guessing you manually disabled the PSCI off for testing?
>
> Anyway I don't see any huge issues with the code itself, small comment 
> below.
>
> > > Test:
> > > - restart:
> > >    # reboot
> > >    Default is cold reset:
> > >    # cat /sys/kernel/reboot/mode
> > >    Switch boot mode to warm reset:
> > >    # echo warm > /sys/kernel/reboot/mode
> > > - power-off:
> > >    # halt
> > >
> > > Tested on AM62-SP-SK board.
> > >
> > > Signed-off-by: Jerome Neanne <jneanne@xxxxxxxxxxxx>
> > > Suggested-by: Andrew Davis <afd@xxxxxx>
> >
> > A review from Andrew would be helpful here.
> >
> > > ---
> > >   drivers/mfd/tps65219.c | 45 +++++++++++++++++++++++++++++++-----------
> > >   1 file changed, 34 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/mfd/tps65219.c b/drivers/mfd/tps65219.c
> > > index 0e402fda206b..c134f3f6e202 100644
> > > --- a/drivers/mfd/tps65219.c
> > > +++ b/drivers/mfd/tps65219.c
> > > @@ -25,25 +25,34 @@ static int tps65219_cold_reset(struct tps65219 *tps)
> > >                     TPS65219_MFP_COLD_RESET_I2C_CTRL_MASK);
> > >   }
> > > -static int tps65219_restart(struct notifier_block *this,
> > > -                unsigned long reboot_mode, void *cmd)
> > > +static int tps65219_soft_shutdown(struct tps65219 *tps)
> > >   {
> > > -    struct tps65219 *tps;
> > > +    return regmap_update_bits(tps->regmap, TPS65219_REG_MFP_CTRL,
> > > +                  TPS65219_MFP_I2C_OFF_REQ_MASK,
> > > +                  TPS65219_MFP_I2C_OFF_REQ_MASK);
> > > +}
> > > -    tps = container_of(this, struct tps65219, nb);
> > > +static int tps65219_power_off_handler(struct sys_off_data *data)
> > > +{
> > > +    tps65219_soft_shutdown(data->cb_data);
> > > +    return NOTIFY_DONE;
> > > +}
> > > +static int tps65219_restart(struct tps65219 *tps,
> > > +                unsigned long reboot_mode)
> > > +{
> > >       if (reboot_mode == REBOOT_WARM)
> > >           tps65219_warm_reset(tps);
> > >       else
> > >           tps65219_cold_reset(tps);
> > > -
> > >       return NOTIFY_DONE;
> > >   }
> > > -static struct notifier_block pmic_rst_restart_nb = {
> > > -    .notifier_call = tps65219_restart,
> > > -    .priority = 200,
> > > -};
> > > +static int tps65219_restart_handler(struct sys_off_data *data)
> > > +{
> > > +    tps65219_restart(data->cb_data, data->mode);
> > > +    return NOTIFY_DONE;
> > > +}
> > >   static const struct resource tps65219_pwrbutton_resources[] = {
> > >       DEFINE_RES_IRQ_NAMED(TPS65219_INT_PB_FALLING_EDGE_DETECT, 
> > > "falling"),
> > > @@ -269,13 +278,27 @@ static int tps65219_probe(struct i2c_client 
> > > *client)
> > >           }
> > >       }
> > > -    tps->nb = pmic_rst_restart_nb;
> > > -    ret = register_restart_handler(&tps->nb);
> > > +    ret = devm_register_sys_off_handler(tps->dev,
> > > +                        SYS_OFF_MODE_RESTART,
> > > +                        SYS_OFF_PRIO_HIGH,
>
> Why not default prio? SYS_OFF_PRIO_DEFAULT
I'm not completely clear about PRIO recommendations. Will follow your 
suggestion.
> Then you can use this new helper devm_register_restart_handler()
Sure!
> > > +                        tps65219_restart_handler,
> > > +                        tps);
> > > +
> > >       if (ret) {
> > >           dev_err(tps->dev, "cannot register restart handler, %d\n", 
> > > ret);
> > >           return ret;
> > >       }
> > > +    ret = devm_register_sys_off_handler(tps->dev,
> > > +                        SYS_OFF_MODE_POWER_OFF,
> > > +                        SYS_OFF_PRIO_DEFAULT,
> > > +                        tps65219_power_off_handler,
> > > +                        tps);
>
>
> devm_register_power_off_handler()?
Oh yes, right, this is solving the PRIO question by construction. This 
is definitely a better option
> Otherwise I see no major issues,
>
> Reviewed-by: Andrew Davis <afd@xxxxxx>
>
> Andrew
>
> > > +    if (ret) {
> > > +        dev_err(tps->dev, "failed to register sys-off handler: %d\n",
> > > +            ret);
> > > +        return ret;
> > > +    }
> > >       return 0;
> > >   }
> > > --
> > > 2.34.1