power: supply: core: add support for custom sysfs attributes

Add functionality to setup device specific sysfs attributes
in a race condition free manner

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/power_supply_core.c

@@ -1018,6 +1018,7 @@ __power_supply_register(struct device *parent,
 	dev_set_drvdata(dev, psy);
 	psy->desc = desc;
 	if (cfg) {
+		dev->groups = cfg->attr_grp;
 		psy->drv_data = cfg->drv_data;
 		psy->of_node =
 			cfg->fwnode ? to_of_node(cfg->fwnode) : cfg->of_node;

include/linux/power_supply.h

@@ -204,6 +204,9 @@ struct power_supply_config {
 	/* Driver private data */
 	void *drv_data;
 
+	/* Device specific sysfs attributes */
+	const struct attribute_group **attr_grp;
+
 	char **supplied_to;
 	size_t num_supplicants;
 };