power: supply: core: Add support for generic fwnodes to power_supply_get_battery_info()

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2071846
Tested: This is one of a series of patch sets to enable Arm SystemReady IR
 support in the kernel for NXP i.MX8 platforms.  This set updates the
 power subsystem.  This set has been tested via simple boot tests and
 the CI loop.

commit c76787b
Author: Hans de Goede <hdegoede@redhat.com>
Date:   Sun Feb 6 19:35:37 2022 +0100

    power: supply: core: Add support for generic fwnodes to power_supply_get_battery_info()

    Add support to power_supply_get_battery_info() to read the properties from
    other fwnode types such as swnodes added by platform code on x86 devices.

    Signed-off-by: Hans de Goede <hdegoede@redhat.com>
    Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
    (cherry picked from commit c76787b)

Signed-off-by: Al Stone <ahs3@redhat.com>

Author: Al Stone

drivers/power/supply/power_supply_core.c

@@ -571,7 +571,8 @@ int power_supply_get_battery_info(struct power_supply *psy,
 {
 	struct power_supply_resistance_temp_table *resist_table;
 	struct power_supply_battery_info *info;
-	struct device_node *battery_np;
+	struct device_node *battery_np = NULL;
+	struct fwnode_reference_args args;
 	struct fwnode_handle *fwnode;
 	const char *value;
 	int err, len, index;
@@ -610,17 +611,21 @@ int power_supply_get_battery_info(struct power_supply *psy,
 		info->ocv_table_size[index]  = -EINVAL;
 	}
 
-	if (!psy->of_node) {
-		dev_warn(&psy->dev, "%s currently only supports devicetree\n",
-			 __func__);
-		return -ENXIO;
-	}
+	if (psy->of_node) {
+		battery_np = of_parse_phandle(psy->of_node, "monitored-battery", 0);
+		if (!battery_np)
+			return -ENODEV;
 
-	battery_np = of_parse_phandle(psy->of_node, "monitored-battery", 0);
-	if (!battery_np)
-		return -ENODEV;
+		fwnode = fwnode_handle_get(of_fwnode_handle(battery_np));
+	} else {
+		err = fwnode_property_get_reference_args(
+					dev_fwnode(psy->dev.parent),
+					"monitored-battery", NULL, 0, 0, &args);
+		if (err)
+			return err;
 
-	fwnode = of_fwnode_handle(battery_np);
+		fwnode = args.fwnode;
+	}
 
 	err = fwnode_property_read_string(fwnode, "compatible", &value);
 	if (err)
@@ -778,6 +783,7 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	*info_out = info;
 
 out_put_node:
+	fwnode_handle_put(fwnode);
 	of_node_put(battery_np);
 	return err;
 }