linux-kernel - Re: [PATCH v2 4/5] power: supply: core: add vendor and product id properties

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Message-ID: <5zjoseyepm3tnqbwrh77liwuuqgmghn4kcj43urnk7z4yrttlx@yqqpnnlifdk5>
Date: Mon, 23 Jun 2025 23:44:03 +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 4/5] power: supply: core: add vendor and product id
 properties

Hi,

On Wed, May 07, 2025 at 06:00:25PM -0700, Amit Sunil Dhamne via B4 Relay wrote:
> From: Amit Sunil Dhamne <amitsd@...gle.com>
> 
> Add the following properties:
>   * Vendor Identifier (VID): Assigned to the battery manufacturer by USB
>     Implementers Forum (USB-IF).
>   * Product Identifier (PID) assigned by the manufacturer to the
>     battery.
> 
> This info is required by USB Type-C PD devices containing batteries.
> This enables the USB Type C devices to respond to a Battery capacity
> request from the port partner by querying for the PID & VID assigned to
> the batteries. Refer to "USB Power Delivery Specification Rev3.1 v1.8"
> Chapter 5.5 Battery_Capabilities Message.
> 
> Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
> ---
>  Documentation/ABI/testing/sysfs-class-power | 19 +++++++++++++++----
>  Documentation/power/power_supply_class.rst  | 11 +++++++++++
>  drivers/power/supply/power_supply_sysfs.c   |  2 ++
>  include/linux/power_supply.h                |  2 ++
>  4 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 2a5c1a09a28f91beec6b18ca7b4492093026bc81..5495e82885b2294cdfd5ace0e7e5fcbeadfccb5f 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -814,11 +814,22 @@ Description:
>  		Access: Read
>  		Valid values: 1-31
>  
> -What:		/sys/class/power_supply/<supply_name>/extensions/<extension_name>
> -Date:		March 2025

Why does this remove existing Documentation?

> +What:		/sys/class/power_supply/<supply_name>/usbif_vendor_id

I think we can use USB_VENDOR_ID and USB_PRODUCT_ID for this like
everyone else?

> +Date:		May 2025
>  Contact:	linux-pm@...r.kernel.org
>  Description:
> -		Reports the extensions registered to the power supply.
> -		Each entry is a link to the device which registered the extension.
> +		Reports the vendor id assigned to the battery manufacturer by USB
> +		Implementers Forum (USB-IF).
>  
>  		Access: Read
> +		Valid values: 0x0-0xffff

If I haven't missed something the formatting will be in decimal. I
think the hex format is more sensible, so this needs some extra
handling in power_supply_format_property() in power_supply_sysfs.c.

> +
> +What:		/sys/class/power_supply/<supply_name>/usbif_product_id
> +Date:		May 2025
> +Contact:	linux-pm@...r.kernel.org
> +Description:
> +		Reports the product id assigned to the battery by the manufacturer
> +		(associated with usbif_vendor_id).
> +
> +		Access: Read
> +		Valid values: 0x0-0xffff
> diff --git a/Documentation/power/power_supply_class.rst b/Documentation/power/power_supply_class.rst
> index da8e275a14ffb9f84bae9ae1efc4720a55ea3010..6d0a6bcf501e719fa4454845b583a8b38d371bb4 100644
> --- a/Documentation/power/power_supply_class.rst
> +++ b/Documentation/power/power_supply_class.rst
> @@ -213,6 +213,17 @@ TIME_TO_FULL
>    seconds left for battery to be considered full
>    (i.e. while battery is charging)
>  
> +USBIF_VENDOR_ID
> +  Vendor ID (VID) assigned to manufacturer or device vendor associated with the
> +  battery by USB Implementers Forum (USB-IF). This property is described in
> +  "USB Power Delivery Specification Rev3.1 V1.8" Chapter 6.5.5 Battery
> +  Capabilities, Section 6.5.5.1 Vendor ID (VID).
> +USBIF_PRODUCT_ID
> +  Product ID (PID) assigned to the battery, such that if the VID belongs to the
> +  manufacturer then the PID will be designated by it. Similarly if the VID
> +  belongs to the device vendor then the PID will be designated by it. This
> +  property is described in "USB Power Delivery Specification Rev3.1 V1.8"
> +  Chapter 6.5.5 Battery Capabilities, Section 6.5.5.2 Product ID (PID).
>  
>  Battery <-> external power supply interaction
>  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index edb058c19c9c44ad9ad97a626fc8f59e3d3735a6..534ed3cd049866fa747455bb6dae1ec2dc5e2da6 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -211,6 +211,8 @@ static struct power_supply_attr power_supply_attrs[] __ro_after_init = {
>  	POWER_SUPPLY_ATTR(TIME_TO_EMPTY_AVG),
>  	POWER_SUPPLY_ATTR(TIME_TO_FULL_NOW),
>  	POWER_SUPPLY_ATTR(TIME_TO_FULL_AVG),
> +	POWER_SUPPLY_ATTR(USBIF_VENDOR_ID),
> +	POWER_SUPPLY_ATTR(USBIF_PRODUCT_ID),
>  	POWER_SUPPLY_ENUM_ATTR(TYPE),
>  	POWER_SUPPLY_ENUM_ATTR(USB_TYPE),
>  	POWER_SUPPLY_ENUM_ATTR(SCOPE),
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index a35b08bd368e9305554e1a608dc8e526983cfa12..100eb559dcede938595ffbf83bc5ef3645a5a172 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -165,6 +165,8 @@ enum power_supply_property {
>  	POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
>  	POWER_SUPPLY_PROP_TIME_TO_FULL_NOW,
>  	POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
> +	POWER_SUPPLY_PROP_USBIF_VENDOR_ID,
> +	POWER_SUPPLY_PROP_USBIF_PRODUCT_ID,
>  	POWER_SUPPLY_PROP_TYPE, /* use power_supply.type instead */
>  	POWER_SUPPLY_PROP_USB_TYPE,
>  	POWER_SUPPLY_PROP_SCOPE,

Neither this series, nor the Pixel 6 one seems to have any user for
these new properties? This becomes part of the kernel ABI, so we do
not add new properties without a user.

Greetings,

-- Sebastian

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