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From: "Ricardo B. Marliere" <ricardo@marliere.net>
Date: Fri, 01 Mar 2024 14:46:15 -0300
Subject: [PATCH] power: supply: core: make power_supply_class constant
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Message-Id: <20240301-class_cleanup-power-v1-1-97e0b7bf9c94@marliere.net>
To: Linus Walleij <linus.walleij@linaro.org>, 
 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/ab8500_btemp.c      |  2 +-
 drivers/power/supply/ab8500_chargalg.c   |  2 +-
 drivers/power/supply/ab8500_charger.c    |  2 +-
 drivers/power/supply/ab8500_fg.c         |  2 +-
 drivers/power/supply/apm_power.c         |  2 +-
 drivers/power/supply/power_supply_core.c | 40 ++++++++++++++++++--------------
 include/linux/power_supply.h             |  2 +-
 7 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/drivers/power/supply/ab8500_btemp.c b/drivers/power/supply/ab8500_btemp.c
index 7905eba93dea..41dba40fffdf 100644
--- a/drivers/power/supply/ab8500_btemp.c
+++ b/drivers/power/supply/ab8500_btemp.c
@@ -617,7 +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,
+	class_for_each_device(&power_supply_class, NULL, psy,
 			      ab8500_btemp_get_ext_psy_data);
 }
 
diff --git a/drivers/power/supply/ab8500_chargalg.c b/drivers/power/supply/ab8500_chargalg.c
index de912658facb..329ae784a72d 100644
--- a/drivers/power/supply/ab8500_chargalg.c
+++ b/drivers/power/supply/ab8500_chargalg.c
@@ -1231,7 +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,
+	class_for_each_device(&power_supply_class, NULL,
 		di->chargalg_psy, ab8500_chargalg_get_ext_psy_data);
 
 	ab8500_chargalg_end_of_charge(di);
diff --git a/drivers/power/supply/ab8500_charger.c b/drivers/power/supply/ab8500_charger.c
index d72f32c663bc..1c2b69bbed17 100644
--- a/drivers/power/supply/ab8500_charger.c
+++ b/drivers/power/supply/ab8500_charger.c
@@ -1949,7 +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,
+	class_for_each_device(&power_supply_class, NULL,
 			      &di->usb_chg, ab8500_charger_get_ext_psy_data);
 
 	/* First run old_vbat is 0. */
diff --git a/drivers/power/supply/ab8500_fg.c b/drivers/power/supply/ab8500_fg.c
index 8c593fbdd45a..e49e704023e1 100644
--- a/drivers/power/supply/ab8500_fg.c
+++ b/drivers/power/supply/ab8500_fg.c
@@ -2407,7 +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,
+	class_for_each_device(&power_supply_class, NULL, psy,
 			      ab8500_fg_get_ext_psy_data);
 }
 
diff --git a/drivers/power/supply/apm_power.c b/drivers/power/supply/apm_power.c
index 9d1a7fbcaed4..034f28699977 100644
--- a/drivers/power/supply/apm_power.c
+++ b/drivers/power/supply/apm_power.c
@@ -79,7 +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,
+	error = class_for_each_device(&power_supply_class, NULL, &bp,
 				      __find_main_battery);
 	if (error) {
 		main_battery = bp.main;
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index 37dac7669090..18232c562a98 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);
@@ -97,7 +100,7 @@ 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,
@@ -191,7 +194,7 @@ static int power_supply_populate_supplied_from(struct power_supply *psy)
 {
 	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);
@@ -226,8 +229,8 @@ static int power_supply_find_supply_from_node(struct device_node *supply_node)
 	 * 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;
 }
@@ -333,7 +336,7 @@ 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);
@@ -369,7 +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,
+	error = class_for_each_device(&power_supply_class, NULL, &count,
 				      __power_supply_is_system_supplied);
 
 	/*
@@ -416,7 +419,7 @@ 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;
@@ -462,8 +465,8 @@ 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,
-					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);
@@ -519,8 +522,8 @@ struct power_supply *power_supply_get_by_phandle(struct device_node *np,
 	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);
 
@@ -1373,7 +1376,7 @@ __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;
@@ -1621,12 +1624,13 @@ EXPORT_SYMBOL_GPL(power_supply_get_drvdata);
 
 static int __init power_supply_class_init(void)
 {
-	power_supply_class = class_create("power_supply");
+	int err;
 
-	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;
@@ -1634,7 +1638,7 @@ 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: 9a451f1b028e116d037a93bf13eb8f8620994205
change-id: 20240301-class_cleanup-power-ac7b0b2660b6

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