Re: [PATCH 2/5] power: supply: core: add function to get supplies from fwnode

[Amit Sunil Dhamne]

On 3/19/25 6:54 AM, Heikki Krogerus wrote:
> On Wed, Mar 12, 2025 at 04:42:02PM -0700, Amit Sunil Dhamne via B4 Relay wrote:
> > From: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
> >
> > Add a new helper function power_supply_get_by_fwnode_reference_array()
> > to retrieve a list of power_supplies associated with the fwnode's
> > property. The property can contain multiple nodes where each node is
> > associated with a power_supply. The list of power_supply objects will be
> > stored in an array supplied by the caller and the return value will
> > indicate the size of the resulting array.
> I don't think this API is necessary. If I've understood what you are
> after here, the batteries should simply have the Type-C psy(s) listed
> in the supplied_to and/or supplied_from.
>
> So you just need to make sure your battery nodes have the USB Type-C
> node(s) listed in the "power-supplies" property in your DT, no?
Thanks Heikki! I will evaluate between this approach vs OF graph 
approach (as suggested in previous review) and implement it in v2.
> thanks,
> > Signed-off-by: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
> > ---
> >   drivers/power/supply/power_supply_core.c | 60 ++++++++++++++++++++++++++++++++
> >   include/linux/power_supply.h             |  5 +++
> >   2 files changed, 65 insertions(+)
> >
> > diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> > index 76c340b38015af0a67a0d91305e6242a8646bf53..df1a52f85125748c4fdcb10687aa7ed2f626ded1 100644
> > --- a/drivers/power/supply/power_supply_core.c
> > +++ b/drivers/power/supply/power_supply_core.c
> > @@ -593,6 +593,66 @@ struct power_supply *devm_power_supply_get_by_phandle(struct device *dev,
> >   EXPORT_SYMBOL_GPL(devm_power_supply_get_by_phandle);
> >   #endif /* CONFIG_OF */
> >   
> > +static int power_supply_match_fwnode(struct device *dev, const void *data)
> > +{
> > +	return dev && dev->parent && dev->parent->fwnode == data;
> > +}
> > +
> > +/**
> > + * power_supply_get_by_fwnode_reference_array() - Returns an array of power
> > + * supply objects associated with each fwnode reference present in the property
> > + * @fwnode: Pointer to fwnode to lookup property
> > + * @property: Name of property holding references
> > + * @psy: Resulting array of power_supply pointers. To be provided by the caller.
> > + * @size: size of power_supply pointer array.
> > + *
> > + * If power supply was found, it increases reference count for the
> > + * internal power supply's device. The user should power_supply_put()
> > + * after usage.
> > + *
> > + * Return: On success returns the number of power supply objects filled
> > + * in the @psy array.
> > + * -EOVERFLOW when size of @psy array is not suffice.
> > + * -EINVAL when @psy is NULL or @size is 0.
> > + * -ENODATA when fwnode does not contain the given property
> > + */
> > +int power_supply_get_by_fwnode_reference_array(struct fwnode_handle *fwnode,
> > +					       const char *property,
> > +					       struct power_supply **psy,
> > +					       ssize_t size)
> > +{
> > +	int ret, index, count = 0;
> > +	struct fwnode_reference_args args;
> > +	struct device *dev;
> > +
> > +	if (!psy || !size)
> > +		return -EINVAL;
> > +
> > +	for (index = 0; index < size &&
> > +	     !(ret = fwnode_property_get_reference_args(fwnode, property, NULL,
> > +							0, index, &args));
> > +	     ++index) {
> > +		dev = class_find_device(&power_supply_class, NULL, args.fwnode,
> > +					power_supply_match_fwnode);
> > +		fwnode_handle_put(args.fwnode);
> > +		if (!dev)
> > +			continue;
> > +
> > +		if (count > size)
> > +			return -EOVERFLOW;
> > +
> > +		psy[count] = dev_get_drvdata(dev);
> > +		atomic_inc(&psy[count]->use_cnt);
> > +		++count;
> > +	}
> > +
> > +	if (ret != -ENOENT)
> > +		return ret;
> > +
> > +	return index ? count : -ENODATA;
> > +}
> > +EXPORT_SYMBOL_GPL(power_supply_get_by_fwnode_reference_array);
> > +
> >   int power_supply_get_battery_info(struct power_supply *psy,
> >   				  struct power_supply_battery_info **info_out)
> >   {
> > diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> > index 6ed53b292162469d7b357734d5589bff18a201d0..3f062607e5cd7c7f04384e34128ae0953e25d981 100644
> > --- a/include/linux/power_supply.h
> > +++ b/include/linux/power_supply.h
> > @@ -820,6 +820,11 @@ devm_power_supply_get_by_phandle(struct device *dev, const char *property)
> >   { return NULL; }
> >   #endif /* CONFIG_OF */
> >   
> > +extern int
> > +power_supply_get_by_fwnode_reference_array(struct fwnode_handle *fwnode,
> > +					   const char *property,
> > +					   struct power_supply **psy,
> > +					   ssize_t size);
> >   extern const enum power_supply_property power_supply_battery_info_properties[];
> >   extern const size_t power_supply_battery_info_properties_size;
> >   extern int power_supply_get_battery_info(struct power_supply *psy,
> >
> > --
> > 2.49.0.rc0.332.g42c0ae87b1-goog