power: supply: core: add power_supply_for_each_device()

Introduce power_supply_for_each_device(), which is a wrapper
for class_for_each_device() using the power_supply_class and
going through all devices.

This allows making the power_supply_class itself a local
variable, so that drivers cannot mess with it and simplifies
the code slightly.
Reviewed-by: Ricardo B. Marliere <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240301-psy-class-cleanup-v1-1-aebe8c4b6b08@collabora.comSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/ab8500_btemp.c

@@ -617,8 +617,7 @@ static int ab8500_btemp_get_ext_psy_data(struct device *dev, void *data)
  */
 static void ab8500_btemp_external_power_changed(struct power_supply *psy)
 {
-	class_for_each_device(&power_supply_class, NULL, psy,
-			      ab8500_btemp_get_ext_psy_data);
+	power_supply_for_each_device(psy, ab8500_btemp_get_ext_psy_data);
 }
 
 /* ab8500 btemp driver interrupts and their respective isr */

drivers/power/supply/ab8500_chargalg.c

@@ -1231,8 +1231,7 @@ static void ab8500_chargalg_algorithm(struct ab8500_chargalg *di)
 	int ret;
 
 	/* Collect data from all power_supply class devices */
-	class_for_each_device(&power_supply_class, NULL,
-		di->chargalg_psy, ab8500_chargalg_get_ext_psy_data);
+	power_supply_for_each_device(di->chargalg_psy, ab8500_chargalg_get_ext_psy_data);
 
 	ab8500_chargalg_end_of_charge(di);
 	ab8500_chargalg_check_temp(di);

drivers/power/supply/ab8500_charger.c

@@ -1949,8 +1949,7 @@ static void ab8500_charger_check_vbat_work(struct work_struct *work)
 	struct ab8500_charger *di = container_of(work,
 		struct ab8500_charger, check_vbat_work.work);
 
-	class_for_each_device(&power_supply_class, NULL,
-			      &di->usb_chg, ab8500_charger_get_ext_psy_data);
+	power_supply_for_each_device(&di->usb_chg, ab8500_charger_get_ext_psy_data);
 
 	/* First run old_vbat is 0. */
 	if (di->old_vbat == 0)

drivers/power/supply/ab8500_fg.c

@@ -2407,8 +2407,7 @@ static int ab8500_fg_init_hw_registers(struct ab8500_fg *di)
  */
 static void ab8500_fg_external_power_changed(struct power_supply *psy)
 {
-	class_for_each_device(&power_supply_class, NULL, psy,
-			      ab8500_fg_get_ext_psy_data);
+	power_supply_for_each_device(psy, ab8500_fg_get_ext_psy_data);
 }
 
 /**

drivers/power/supply/apm_power.c

@@ -79,8 +79,7 @@ static void find_main_battery(void)
 	main_battery = NULL;
 	bp.main = main_battery;
 
-	error = class_for_each_device(&power_supply_class, NULL, &bp,
-				      __find_main_battery);
+	error = power_supply_for_each_device(&bp, __find_main_battery);
 	if (error) {
 		main_battery = bp.main;
 		return;

drivers/power/supply/power_supply_core.c

@@ -25,12 +25,10 @@
 #include "power_supply.h"
 #include "samsung-sdi-battery.h"
 
-/* exported for the APM Power driver, APM emulation */
-const struct class power_supply_class = {
+static const struct class power_supply_class = {
 	.name = "power_supply",
 	.dev_uevent = power_supply_uevent,
 };
-EXPORT_SYMBOL_GPL(power_supply_class);
 
 static BLOCKING_NOTIFIER_HEAD(power_supply_notifier);
 
@@ -100,8 +98,7 @@ static void power_supply_changed_work(struct work_struct *work)
 	if (likely(psy->changed)) {
 		psy->changed = false;
 		spin_unlock_irqrestore(&psy->changed_lock, flags);
-		class_for_each_device(&power_supply_class, NULL, psy,
-				      __power_supply_changed_work);
+		power_supply_for_each_device(psy, __power_supply_changed_work);
 		power_supply_update_leds(psy);
 		blocking_notifier_call_chain(&power_supply_notifier,
 				PSY_EVENT_PROP_CHANGED, psy);
@@ -119,6 +116,12 @@ static void power_supply_changed_work(struct work_struct *work)
 	spin_unlock_irqrestore(&psy->changed_lock, flags);
 }
 
+int power_supply_for_each_device(void *data, int (*fn)(struct device *dev, void *data))
+{
+	return class_for_each_device(&power_supply_class, NULL, data, fn);
+}
+EXPORT_SYMBOL_GPL(power_supply_for_each_device);
+
 void power_supply_changed(struct power_supply *psy)
 {
 	unsigned long flags;
@@ -194,8 +197,7 @@ static int power_supply_populate_supplied_from(struct power_supply *psy)
 {
 	int error;
 
-	error = class_for_each_device(&power_supply_class, NULL, psy,
-				      __power_supply_populate_supplied_from);
+	error = power_supply_for_each_device(psy, __power_supply_populate_supplied_from);
 
 	dev_dbg(&psy->dev, "%s %d\n", __func__, error);
 
@@ -208,7 +210,7 @@ static int  __power_supply_find_supply_from_node(struct device *dev,
 	struct device_node *np = data;
 	struct power_supply *epsy = dev_get_drvdata(dev);
 
-	/* returning non-zero breaks out of class_for_each_device loop */
+	/* returning non-zero breaks out of power_supply_for_each_device loop */
 	if (epsy->of_node == np)
 		return 1;
 
@@ -220,17 +222,16 @@ static int power_supply_find_supply_from_node(struct device_node *supply_node)
 	int error;
 
 	/*
-	 * class_for_each_device() either returns its own errors or values
+	 * power_supply_for_each_device() either returns its own errors or values
 	 * returned by __power_supply_find_supply_from_node().
 	 *
 	 * __power_supply_find_supply_from_node() will return 0 (no match)
 	 * or 1 (match).
 	 *
-	 * We return 0 if class_for_each_device() returned 1, -EPROBE_DEFER if
+	 * We return 0 if power_supply_for_each_device() returned 1, -EPROBE_DEFER if
 	 * it returned 0, or error as returned by it.
 	 */
-	error = class_for_each_device(&power_supply_class, NULL, supply_node,
-				      __power_supply_find_supply_from_node);
+	error = power_supply_for_each_device(supply_node, __power_supply_find_supply_from_node);
 
 	return error ? (error == 1 ? 0 : error) : -EPROBE_DEFER;
 }
@@ -336,8 +337,7 @@ int power_supply_am_i_supplied(struct power_supply *psy)
 	struct psy_am_i_supplied_data data = { psy, 0 };
 	int error;
 
-	error = class_for_each_device(&power_supply_class, NULL, &data,
-				      __power_supply_am_i_supplied);
+	error = power_supply_for_each_device(&data, __power_supply_am_i_supplied);
 
 	dev_dbg(&psy->dev, "%s count %u err %d\n", __func__, data.count, error);
 
@@ -372,8 +372,7 @@ int power_supply_is_system_supplied(void)
 	int error;
 	unsigned int count = 0;
 
-	error = class_for_each_device(&power_supply_class, NULL, &count,
-				      __power_supply_is_system_supplied);
+	error = power_supply_for_each_device(&count, __power_supply_is_system_supplied);
 
 	/*
 	 * If no system scope power class device was found at all, most probably we
@@ -419,8 +418,7 @@ int power_supply_get_property_from_supplier(struct power_supply *psy,
 	 * This function is not intended for use with a supply with multiple
 	 * suppliers, we simply pick the first supply to report the psp.
 	 */
-	ret = class_for_each_device(&power_supply_class, NULL, &data,
-				    __power_supply_get_supplier_property);
+	ret = power_supply_for_each_device(&data, __power_supply_get_supplier_property);
 	if (ret < 0)
 		return ret;
 	if (ret == 0)

include/linux/power_supply.h

@@ -894,8 +894,7 @@ extern int power_supply_powers(struct power_supply *psy, struct device *dev);
 #define to_power_supply(device) container_of(device, struct power_supply, dev)
 
 extern void *power_supply_get_drvdata(struct power_supply *psy);
-/* For APM emulation, think legacy userspace. */
-extern const struct class power_supply_class;
+extern int power_supply_for_each_device(void *data, int (*fn)(struct device *dev, void *data));
 
 static inline bool power_supply_is_amp_property(enum power_supply_property psp)
 {