Re: [PATCH v6 4/4] power: supply: core: add UAPI to discover currently used extensions

[Armin Wolf <W_Armin@gmx.de>]

Am 11.12.24 um 20:57 schrieb Thomas Weißschuh:

> Userspace wants to now about the used power supply extensions,
> for example to handle a device extended by a certain extension
> differently or to discover information about the extending device.
>
> Add a sysfs directory to the power supply device.
> This directory contains links which are named after the used extension
> and point to the device implementing that extension.

Reviewed-by: Armin Wolf <W_Armin@gmx.de>

> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
>   Documentation/ABI/testing/sysfs-class-power |  9 +++++++++
>   drivers/power/supply/cros_charge-control.c  |  5 ++++-
>   drivers/power/supply/power_supply.h         |  2 ++
>   drivers/power/supply/power_supply_core.c    | 19 +++++++++++++++++--
>   drivers/power/supply/power_supply_sysfs.c   | 10 ++++++++++
>   drivers/power/supply/test_power.c           |  4 +++-
>   include/linux/power_supply.h                |  2 ++
>   7 files changed, 47 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-power b/Documentation/ABI/testing/sysfs-class-power
> index 45180b62d42686c8999eda54f38435cb6c74a879..31e8b33d849cbe99dc93a4ba3723a43440ac3103 100644
> --- a/Documentation/ABI/testing/sysfs-class-power
> +++ b/Documentation/ABI/testing/sysfs-class-power
> @@ -793,3 +793,12 @@ Description:
>
>   		Access: Read
>   		Valid values: 1-31
> +
> +What:		/sys/class/power_supply/<supply_name>/extensions/<extension_name>
> +Date:		March 2025
> +Contact:	linux-pm@vger.kernel.org
> +Description:
> +		Reports the extensions registered to the power supply.
> +		Each entry is a link to the device which registered the extension.
> +
> +		Access: Read
> diff --git a/drivers/power/supply/cros_charge-control.c b/drivers/power/supply/cros_charge-control.c
> index fb4af232721dec1d4f0090f6616922848812b2a2..02d5bdbe2e8d45108dd8f2d3ab6a927b94864b9e 100644
> --- a/drivers/power/supply/cros_charge-control.c
> +++ b/drivers/power/supply/cros_charge-control.c
> @@ -31,6 +31,7 @@
>    */
>
>   struct cros_chctl_priv {
> +	struct device *dev;
>   	struct cros_ec_device *cros_ec;
>   	struct acpi_battery_hook battery_hook;
>   	struct power_supply *hooked_battery;
> @@ -202,6 +203,7 @@ static int cros_chctl_psy_prop_is_writeable(struct power_supply *psy,
>   	};									\
>   										\
>   	static const struct power_supply_ext _name = {				\
> +		.name			= "cros-charge-control",		\
>   		.properties		= _name ## _props,			\
>   		.num_properties		= ARRAY_SIZE(_name ## _props),		\
>   		.charge_behaviours	= EC_CHARGE_CONTROL_BEHAVIOURS,		\
> @@ -233,7 +235,7 @@ static int cros_chctl_add_battery(struct power_supply *battery, struct acpi_batt
>   		return 0;
>
>   	priv->hooked_battery = battery;
> -	return power_supply_register_extension(battery, priv->psy_ext, priv);
> +	return power_supply_register_extension(battery, priv->psy_ext, priv->dev, priv);
>   }
>
>   static int cros_chctl_remove_battery(struct power_supply *battery, struct acpi_battery_hook *hook)
> @@ -299,6 +301,7 @@ static int cros_chctl_probe(struct platform_device *pdev)
>
>   	dev_dbg(dev, "Command version: %u\n", (unsigned int)priv->cmd_version);
>
> +	priv->dev = dev;
>   	priv->cros_ec = cros_ec;
>
>   	if (priv->cmd_version == 1)
> diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
> index 531785516d2ac31f9a7f73a58e15e64cb81820ed..9ed749cd09369f0f13017847687509736b30aae8 100644
> --- a/drivers/power/supply/power_supply.h
> +++ b/drivers/power/supply/power_supply.h
> @@ -25,6 +25,7 @@ extern bool power_supply_ext_has_property(const struct power_supply_ext *ext,
>   struct power_supply_ext_registration {
>   	struct list_head list_head;
>   	const struct power_supply_ext *ext;
> +	struct device *dev;
>   	void *data;
>   };
>
> @@ -39,6 +40,7 @@ struct power_supply_ext_registration {
>
>   extern void __init power_supply_init_attrs(void);
>   extern int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env);
> +extern const struct attribute_group power_supply_extension_group;
>   extern const struct attribute_group *power_supply_attr_groups[];
>
>   #else
> diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
> index bc22edbd0e6a02c27500132075f5c98d814a7330..5142fbd580ee3d629a2aae7d0b9bcd5709162129 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -1346,17 +1346,21 @@ static int power_supply_update_sysfs_and_hwmon(struct power_supply *psy)
>   }
>
>   int power_supply_register_extension(struct power_supply *psy, const struct power_supply_ext *ext,
> -				    void *data)
> +				    struct device *dev, void *data)
>   {
>   	struct power_supply_ext_registration *reg;
>   	size_t i;
>   	int ret;
>
> -	if (!psy || !ext || !ext->properties || !ext->num_properties)
> +	if (!psy || !dev || !ext || !ext->name || !ext->properties || !ext->num_properties)
>   		return -EINVAL;
>
>   	guard(rwsem_write)(&psy->extensions_sem);
>
> +	power_supply_for_each_extension(reg, psy)
> +		if (strcmp(ext->name, reg->ext->name) == 0)
> +			return -EEXIST;
> +
>   	for (i = 0; i < ext->num_properties; i++)
>   		if (power_supply_has_property(psy, ext->properties[i]))
>   			return -EEXIST;
> @@ -1366,9 +1370,15 @@ int power_supply_register_extension(struct power_supply *psy, const struct power
>   		return -ENOMEM;
>
>   	reg->ext = ext;
> +	reg->dev = dev;
>   	reg->data = data;
>   	list_add(&reg->list_head, &psy->extensions);
>
> +	ret = sysfs_add_link_to_group(&psy->dev.kobj, power_supply_extension_group.name,
> +				      &dev->kobj, ext->name);
> +	if (ret)
> +		goto sysfs_link_failed;
> +
>   	ret = power_supply_update_sysfs_and_hwmon(psy);
>   	if (ret)
>   		goto sysfs_hwmon_failed;
> @@ -1376,6 +1386,8 @@ int power_supply_register_extension(struct power_supply *psy, const struct power
>   	return 0;
>
>   sysfs_hwmon_failed:
> +	sysfs_remove_link_from_group(&psy->dev.kobj, power_supply_extension_group.name, ext->name);
> +sysfs_link_failed:
>   	list_del(&reg->list_head);
>   	kfree(reg);
>   	return ret;
> @@ -1392,6 +1404,9 @@ void power_supply_unregister_extension(struct power_supply *psy, const struct po
>   		if (reg->ext == ext) {
>   			list_del(&reg->list_head);
>   			kfree(reg);
> +			sysfs_remove_link_from_group(&psy->dev.kobj,
> +						     power_supply_extension_group.name,
> +						     reg->ext->name);
>   			power_supply_update_sysfs_and_hwmon(psy);
>   			return;
>   		}
> diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
> index 927ddb9d83bb7259809ba695cb9398d1ad654b46..aadc41ca741d8acd27a83f6bd01d578d7877e7c2 100644
> --- a/drivers/power/supply/power_supply_sysfs.c
> +++ b/drivers/power/supply/power_supply_sysfs.c
> @@ -421,8 +421,18 @@ static const struct attribute_group power_supply_attr_group = {
>   	.is_visible = power_supply_attr_is_visible,
>   };
>
> +static struct attribute *power_supply_extension_attrs[] = {
> +	NULL
> +};
> +
> +const struct attribute_group power_supply_extension_group = {
> +	.name = "extensions",
> +	.attrs = power_supply_extension_attrs,
> +};
> +
>   const struct attribute_group *power_supply_attr_groups[] = {
>   	&power_supply_attr_group,
> +	&power_supply_extension_group,
>   	NULL
>   };
>
> diff --git a/drivers/power/supply/test_power.c b/drivers/power/supply/test_power.c
> index 66f9ef52e0f3e6e6e6bebcfd438c2acd421284ec..2a975a110f4859a77f7689369675f2008816d704 100644
> --- a/drivers/power/supply/test_power.c
> +++ b/drivers/power/supply/test_power.c
> @@ -293,6 +293,7 @@ static int test_power_battery_extproperty_is_writeable(struct power_supply *psy,
>   }
>
>   static const struct power_supply_ext test_power_battery_ext = {
> +	.name			= "test_power",
>   	.properties		= test_power_battery_extprops,
>   	.num_properties		= ARRAY_SIZE(test_power_battery_extprops),
>   	.get_property		= test_power_battery_extget_property,
> @@ -307,7 +308,8 @@ static void test_power_configure_battery_extension(bool enable)
>   	psy = test_power_supplies[TEST_BATTERY];
>
>   	if (enable) {
> -		if (power_supply_register_extension(psy, &test_power_battery_ext, NULL)) {
> +		if (power_supply_register_extension(psy, &test_power_battery_ext, &psy->dev,
> +						    NULL)) {
>   			pr_err("registering battery extension failed\n");
>   			return;
>   		}
> diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
> index e434516086f032cdb4698005bb1a99eda303a307..88a7bd34c8a74d694013aaaebd30269b30509e8b 100644
> --- a/include/linux/power_supply.h
> +++ b/include/linux/power_supply.h
> @@ -284,6 +284,7 @@ struct power_supply_desc {
>   };
>
>   struct power_supply_ext {
> +	const char *const name;
>   	u8 charge_behaviours;
>   	const enum power_supply_property *properties;
>   	size_t num_properties;
> @@ -907,6 +908,7 @@ extern int power_supply_powers(struct power_supply *psy, struct device *dev);
>   extern int __must_check
>   power_supply_register_extension(struct power_supply *psy,
>   				const struct power_supply_ext *ext,
> +				struct device *dev,
>   				void *data);
>   extern void power_supply_unregister_extension(struct power_supply *psy,
>   					      const struct power_supply_ext *ext);
>