Re: [PATCH v2] rtc: rv3028: Improve trickle charger logic

[Andrej Picej <andrej.picej@xxxxxxxxx>]

Hi Alexandre,

On 22. 06. 23 09:34, Alexandre Belloni wrote:
> On 22/06/2023 09:16:09+0200, Andrej Picej wrote:
> > Property "trickle-resistor-ohms" allows us to set trickle charger
> > resistor. However there is no possibility to disable it afterwards.
> >
> >  From now on, disable trickle charger circuit in case device-tree
> > property "trickle-resistor-ohms" is set to -1.
> >
> > Additionally, lets make sure we only update internal EEPROM in case of a
> > change. This prevents wear due to excessive EEPROM writes on each probe.
> >
> > Signed-off-by: Andrej Picej <andrej.picej@xxxxxxxxx>
> > ---
> > Changes in v2:
> > - disable trickle charger if device tree property trickle-resistor-ohms
> >    is set to -1.
>
> What about using aux-voltage-chargeable which is the generic property
> for this?

I thought that this is more of a property for specifying if connected 
battery/supercap has charging capabilities. I guess at the end it would 
be the same thing as knowingly disabling the trickle charger even if 
battery/supercap can be charged.
Do you want that I change and use "aux-voltage-chargeable"?

BR,
Andrej

> > ---
> >   drivers/rtc/rtc-rv3028.c | 45 +++++++++++++++++++++++++++++-----------
> >   1 file changed, 33 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
> > index ec5d7a614e2d..da2ae81fe7c8 100644
> > --- a/drivers/rtc/rtc-rv3028.c
> > +++ b/drivers/rtc/rtc-rv3028.c
> > @@ -859,7 +859,8 @@ static int rv3028_probe(struct i2c_client *client)
> >   {
> >   	struct rv3028_data *rv3028;
> >   	int ret, status;
> > -	u32 ohms;
> > +	s32 ohms;
> > +	int val_old, val;
> >   	struct nvmem_config nvmem_cfg = {
> >   		.name = "rv3028_nvram",
> >   		.word_size = 1,
> > @@ -937,22 +938,42 @@ static int rv3028_probe(struct i2c_client *client)
> >   	if (ret)
> >   		return ret;
> >   
> > -	/* setup trickle charger */
> > -	if (!device_property_read_u32(&client->dev, "trickle-resistor-ohms",
> > -				      &ohms)) {
> > -		int i;
> > +	ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &val_old);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	/* mask out only trickle charger bits */
> > +	val_old = val_old & (RV3028_BACKUP_TCE | RV3028_BACKUP_TCR_MASK);
> >   
> > -		for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
> > -			if (ohms == rv3028_trickle_resistors[i])
> > -				break;
> > +	/* setup trickle charger */
> > +	if (!of_property_read_s32(client->dev.of_node, "trickle-resistor-ohms",
> > +				  &ohms)) {
> > +		/* disable trickle charger if trickle-resistor-ohms = <(-1)>; */
> > +		if (ohms == -1) {
> > +			val = val_old & ~RV3028_BACKUP_TCE;
> > +		} else {
> > +			int i;
> > +
> > +			for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
> > +				if (ohms == rv3028_trickle_resistors[i])
> > +					break;
> > +
> > +			if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
> > +				/* enable trickle charger and its resistor */
> > +				val = RV3028_BACKUP_TCE | i;
> > +			} else {
> > +				dev_warn(&client->dev, "invalid trickle resistor value\n");
> > +				/* don't update the trickle charger regs */
> > +				val = val_old;
> > +			}
> > +		}
> >   
> > -		if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
> > +		/* only update EEPROM if changes are necessary */
> > +		if (val_old != val) {
> >   			ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, RV3028_BACKUP_TCE |
> > -						 RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | i);
> > +						RV3028_BACKUP_TCR_MASK, val);
> >   			if (ret)
> >   				return ret;
> > -		} else {
> > -			dev_warn(&client->dev, "invalid trickle resistor value\n");
> >   		}
> >   	}
> >   
> > --
> > 2.25.1