linux-kernel - Re: [PATCH v2 2/5] power: supply: core: add helper to get power supply given a fwnode

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Message-ID: <djqmdlnsftquum3wayigqryzfy7xkn67uj4pfk3wugxl3lx3wr@y26ydci57iwi>
Date: Mon, 23 Jun 2025 23:21:22 +0200
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: amitsd@...gle.com
Cc: Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Badhri Jagan Sridharan <badhri@...gle.com>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@...nel.org>, Kyle Tso <kyletso@...gle.com>, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 2/5] power: supply: core: add helper to get power
 supply given a fwnode

Hi,

On Wed, May 07, 2025 at 06:00:23PM -0700, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@...gle.com>
> 
> Add a helper function power_supply_get_by_fwnode() to retrieve
> power_supply given a valid fwnode reference.
> 
> Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
> ---
>  drivers/power/supply/power_supply_core.c | 30 ++++++++++++++++++++++++++++++
>  include/linux/power_supply.h             |  3 +++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index 76c340b38015af0a67a0d91305e6242a8646bf53..ef6ba22b837b0b9463f9a3065425e2720f40b9eb 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -496,6 +496,36 @@ struct power_supply *power_supply_get_by_name(const char *name)
>  }
>  EXPORT_SYMBOL_GPL(power_supply_get_by_name);
>  
> +static int power_supply_match_device_by_fwnode(struct device *dev, const void *data)
> +{
> +	return dev->parent && dev_fwnode(dev->parent) == data;
> +}

This already exists as power_supply_match_device_fwnode().

> +
> +/**
> + * power_supply_get_by_fwnode() - Search for power supply given a fwnode ref.
> + * @fwnode: fwnode reference
> + *
> + * If power supply was found, it increases reference count for the internal
> + * power supply's device. The user should power_supply_put() after use.
> + *
> + * Return: Reference to power_supply node matching the fwnode on success or
> + * NULL on failure.
> + */
> +struct power_supply *power_supply_get_by_fwnode(struct fwnode_handle *fwnode)
> +{
> +	struct power_supply *psy = NULL;
> +	struct device *dev = class_find_device(&power_supply_class, NULL, fwnode,
> +					       power_supply_match_device_by_fwnode);
> +
> +	if (dev) {
> +		psy = dev_get_drvdata(dev);
> +		atomic_inc(&psy->use_cnt);
> +	}
> +
> +	return psy;
> +}
> +EXPORT_SYMBOL_GPL(power_supply_get_by_fwnode);

And this is a 50% of power_supply_get_by_reference(), so the
function should be updated to use power_supply_get_by_fwnode().

Greetings,

-- Sebastian

>  /**
>   * power_supply_put() - Drop reference obtained with power_supply_get_by_name
>   * @psy: Reference to put
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index 6ed53b292162469d7b357734d5589bff18a201d0..a35b08bd368e9305554e1a608dc8e526983cfa12 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -801,10 +801,13 @@ extern void power_supply_unreg_notifier(struct notifier_block *nb);
>  #if IS_ENABLED(CONFIG_POWER_SUPPLY)
>  extern struct power_supply *power_supply_get_by_name(const char *name);
>  extern void power_supply_put(struct power_supply *psy);
> +extern struct power_supply *power_supply_get_by_fwnode(struct fwnode_handle *fwnode);
>  #else
>  static inline void power_supply_put(struct power_supply *psy) {}
>  static inline struct power_supply *power_supply_get_by_name(const char *name)
>  { return NULL; }
> +static inline struct power_supply *power_supply_get_by_fwnode(struct fwnode_handle *fwnode)
> +{ return NULL; }
>  #endif
>  #ifdef CONFIG_OF
>  extern struct power_supply *power_supply_get_by_phandle(struct device_node *np,
> 
> -- 
> 2.49.0.987.g0cc8ee98dc-goog
> 
> 

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