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: <b6bfc569-159d-4249-821d-cb6ffab17000@google.com>
Date: Mon, 7 Jul 2025 17:53:30 -0700
From: Amit Sunil Dhamne <amitsd@...gle.com>
To: Sebastian Reichel <sebastian.reichel@...labora.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 Sebastian,

On 6/23/25 2:21 PM, Sebastian Reichel wrote:
> 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().

Thanks for your review! I will update in the next revision


>
>> +
>> +/**
>> + * 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().

Agreed.


Thanks,

Amit


>
> 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
>>
>>