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

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Wed, Mar 12, 2025 at 04:42:02PM -0700, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@google.com>
> 
> 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,

> Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
> ---
>  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
> 

-- 
heikki