power: supply: core: make power_supply_class constant

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the power_supply_class structure to be declared at build
time placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <[e-mail]>
Suggested-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Ricardo B. Marliere <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/ab8500_btemp.c

···
  */
 static void ab8500_btemp_external_power_changed(struct power_supply *psy)
 {
-	class_for_each_device(power_supply_class, NULL, psy,
+	class_for_each_device(&power_supply_class, NULL, psy,
 			      ab8500_btemp_get_ext_psy_data);
 }
 

drivers/power/supply/ab8500_chargalg.c

···
 	int ret;
 
 	/* Collect data from all power_supply class devices */
-	class_for_each_device(power_supply_class, NULL,
+	class_for_each_device(&power_supply_class, NULL,
 		di->chargalg_psy, ab8500_chargalg_get_ext_psy_data);
 
 	ab8500_chargalg_end_of_charge(di);

drivers/power/supply/ab8500_charger.c

···
 	struct ab8500_charger *di = container_of(work,
 		struct ab8500_charger, check_vbat_work.work);
 
-	class_for_each_device(power_supply_class, NULL,
+	class_for_each_device(&power_supply_class, NULL,
 			      &di->usb_chg, ab8500_charger_get_ext_psy_data);
 
 	/* First run old_vbat is 0. */

drivers/power/supply/ab8500_fg.c

···
  */
 static void ab8500_fg_external_power_changed(struct power_supply *psy)
 {
-	class_for_each_device(power_supply_class, NULL, psy,
+	class_for_each_device(&power_supply_class, NULL, psy,
 			      ab8500_fg_get_ext_psy_data);
 }
 

drivers/power/supply/apm_power.c

···
 	main_battery = NULL;
 	bp.main = main_battery;
 
-	error = class_for_each_device(power_supply_class, NULL, &bp,
+	error = class_for_each_device(&power_supply_class, NULL, &bp,
 				      __find_main_battery);
 	if (error) {
 		main_battery = bp.main;

drivers/power/supply/power_supply_core.c

···
 #include "samsung-sdi-battery.h"
 
 /* exported for the APM Power driver, APM emulation */
-struct class *power_supply_class;
+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);
···
 	if (likely(psy->changed)) {
 		psy->changed = false;
 		spin_unlock_irqrestore(&psy->changed_lock, flags);
-		class_for_each_device(power_supply_class, NULL, psy,
+		class_for_each_device(&power_supply_class, NULL, psy,
 				      __power_supply_changed_work);
 		power_supply_update_leds(psy);
 		blocking_notifier_call_chain(&power_supply_notifier,
···
 {
 	int error;
 
-	error = class_for_each_device(power_supply_class, NULL, psy,
+	error = class_for_each_device(&power_supply_class, NULL, psy,
 				      __power_supply_populate_supplied_from);
 
 	dev_dbg(&psy->dev, "%s %d\n", __func__, error);
···
 	 * We return 0 if class_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 = class_for_each_device(&power_supply_class, NULL, supply_node,
+				      __power_supply_find_supply_from_node);
 
 	return error ? (error == 1 ? 0 : error) : -EPROBE_DEFER;
 }
···
 	struct psy_am_i_supplied_data data = { psy, 0 };
 	int error;
 
-	error = class_for_each_device(power_supply_class, NULL, &data,
+	error = class_for_each_device(&power_supply_class, NULL, &data,
 				      __power_supply_am_i_supplied);
 
 	dev_dbg(&psy->dev, "%s count %u err %d\n", __func__, data.count, error);
···
 	int error;
 	unsigned int count = 0;
 
-	error = class_for_each_device(power_supply_class, NULL, &count,
+	error = class_for_each_device(&power_supply_class, NULL, &count,
 				      __power_supply_is_system_supplied);
 
 	/*
···
 	 * 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,
+	ret = class_for_each_device(&power_supply_class, NULL, &data,
 				    __power_supply_get_supplier_property);
 	if (ret < 0)
 		return ret;
···
 struct power_supply *power_supply_get_by_name(const char *name)
 {
 	struct power_supply *psy = NULL;
-	struct device *dev = class_find_device(power_supply_class, NULL, name,
-					power_supply_match_device_by_name);
+	struct device *dev = class_find_device(&power_supply_class, NULL, name,
+					       power_supply_match_device_by_name);
 
 	if (dev) {
 		psy = dev_get_drvdata(dev);
···
 	if (!power_supply_np)
 		return ERR_PTR(-ENODEV);
 
-	dev = class_find_device(power_supply_class, NULL, power_supply_np,
-						power_supply_match_device_node);
+	dev = class_find_device(&power_supply_class, NULL, power_supply_np,
+				power_supply_match_device_node);
 
 	of_node_put(power_supply_np);
 
···
 
 	device_initialize(dev);
 
-	dev->class = power_supply_class;
+	dev->class = &power_supply_class;
 	dev->type = &power_supply_dev_type;
 	dev->parent = parent;
 	dev->release = power_supply_dev_release;
···
 
 static int __init power_supply_class_init(void)
 {
-	power_supply_class = class_create("power_supply");
+	int err;
 
-	if (IS_ERR(power_supply_class))
-		return PTR_ERR(power_supply_class);
+	err = class_register(&power_supply_class);
+	if (err)
+		return err;
 
-	power_supply_class->dev_uevent = power_supply_uevent;
 	power_supply_init_attrs();
 
 	return 0;
···
 
 static void __exit power_supply_class_exit(void)
 {
-	class_destroy(power_supply_class);
+	class_unregister(&power_supply_class);
 }
 
 subsys_initcall(power_supply_class_init);

include/linux/power_supply.h

···
 
 extern void *power_supply_get_drvdata(struct power_supply *psy);
 /* For APM emulation, think legacy userspace. */
-extern struct class *power_supply_class;
+extern const struct class power_supply_class;
 
 static inline bool power_supply_is_amp_property(enum power_supply_property psp)
 {