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From: "Ricardo B. Marliere" <ricardo@marliere.net>
Date: Tue, 20 Feb 2024 19:41:26 -0300
Subject: [PATCH] power: supply: core: make power_supply_class constant
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Message-Id: <20240220-class_cleanup-power-v1-1-9ef579404351@marliere.net>
To: Sebastian Reichel <sre@kernel.org>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, 
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
 "Ricardo B. Marliere" <ricardo@marliere.net>

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 <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
 drivers/power/supply/power_supply_core.c | 28 ++++++++++++++++------------
 include/linux/power_supply.h             |  2 +-
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index ecef35ac3b7e..f13372e88589 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -26,7 +26,10 @@
 #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);
@@ -93,7 +96,7 @@ 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,
+		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,
@@ -329,7 +332,7 @@ 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,
+	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);
@@ -365,7 +368,7 @@ int power_supply_is_system_supplied(void)
 	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);
 
 	/*
@@ -412,7 +415,7 @@ 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,
+	ret = class_for_each_device(&power_supply_class, NULL, &data,
 				    __power_supply_get_supplier_property);
 	if (ret < 0)
 		return ret;
@@ -458,7 +461,7 @@ static int power_supply_match_device_by_name(struct device *dev, const void *dat
 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,
+	struct device *dev = class_find_device(&power_supply_class, NULL, name,
 					power_supply_match_device_by_name);
 
 	if (dev) {
@@ -1369,7 +1372,7 @@ __power_supply_register(struct device *parent,
 
 	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;
@@ -1617,12 +1620,13 @@ EXPORT_SYMBOL_GPL(power_supply_get_drvdata);
 
 static int __init power_supply_class_init(void)
 {
-	power_supply_class = class_create("power_supply");
+	int err;
+
+	err = class_register(&power_supply_class);
 
-	if (IS_ERR(power_supply_class))
-		return PTR_ERR(power_supply_class);
+	if (err)
+		return err;
 
-	power_supply_class->dev_uevent = power_supply_uevent;
 	power_supply_init_attrs(&power_supply_dev_type);
 
 	return 0;
@@ -1630,7 +1634,7 @@ static int __init power_supply_class_init(void)
 
 static void __exit power_supply_class_exit(void)
 {
-	class_destroy(power_supply_class);
+	class_unregister(&power_supply_class);
 }
 
 subsys_initcall(power_supply_class_init);
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index c0992a77feea..514f652de64d 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -895,7 +895,7 @@ extern int power_supply_powers(struct power_supply *psy, struct device *dev);
 
 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)
 {

---
base-commit: a9b254892ce1a447b06c5019cbf0e9caeb48c138
change-id: 20240220-class_cleanup-power-14680219753d

Best regards,
-- 
Ricardo B. Marliere <ricardo@marliere.net>