power_supply: Change ownership from driver to core

Change the ownership of power_supply structure from each driver
implementing the class to the power supply core.

The patch changes power_supply_register() function thus all drivers
implementing power supply class are adjusted.

Each driver provides the implementation of power supply. However it
should not be the owner of power supply class instance because it is
exposed by core to other subsystems with power_supply_get_by_name().
These other subsystems have no knowledge when the driver will unregister
the power supply. This leads to several issues when driver is unbound -
mostly because user of power supply accesses freed memory.

Instead let the core own the instance of struct 'power_supply'.  Other
users of this power supply will still access valid memory because it
will be freed when device reference count reaches 0. Currently this
means "it will leak" but power_supply_put() call in next patches will
solve it.

This solves invalid memory references in following race condition
scenario:

Thread 1: charger manager
Thread 2: power supply driver, used by charger manager

THREAD 1 (charger manager)         THREAD 2 (power supply driver)
==========================         ==============================
psy = power_supply_get_by_name()
                                   Driver unbind, .remove
                                     power_supply_unregister()
                                     Device fully removed
psy->get_property()

The 'get_property' call is executed in invalid context because the driver was
unbound and struct 'power_supply' memory was freed.

This could be observed easily with charger manager driver (here compiled
with max17040 fuel gauge):

$ cat /sys/devices/virtual/power_supply/cm-battery/capacity &
$ echo "1-0036" > /sys/bus/i2c/drivers/max17040/unbind
[   55.725123] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   55.732584] pgd = d98d4000
[   55.734060] [00000000] *pgd=5afa2831, *pte=00000000, *ppte=00000000
[   55.740318] Internal error: Oops: 80000007 [#1] PREEMPT SMP ARM
[   55.746210] Modules linked in:
[   55.749259] CPU: 1 PID: 2936 Comm: cat Tainted: G        W       3.19.0-rc1-next-20141226-00048-gf79f475f3c44-dirty #1496
[   55.760190] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[   55.766270] task: d9b76f00 ti: daf54000 task.ti: daf54000
[   55.771647] PC is at 0x0
[   55.774182] LR is at charger_get_property+0x2f4/0x36c
[   55.779201] pc : [<00000000>]    lr : [<c034b0b4>]    psr: 60000013
[   55.779201] sp : daf55e90  ip : 00000003  fp : 00000000
[   55.790657] r10: 00000000  r9 : c06e2878  r8 : d9b26c68
[   55.795865] r7 : dad81610  r6 : daec7410  r5 : daf55ebc  r4 : 00000000
[   55.802367] r3 : 00000000  r2 : daf55ebc  r1 : 0000002a  r0 : d9b26c68
[   55.808879] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   55.815994] Control: 10c5387d  Table: 598d406a  DAC: 00000015
[   55.821723] Process cat (pid: 2936, stack limit = 0xdaf54210)
[   55.827451] Stack: (0xdaf55e90 to 0xdaf56000)
[   55.831795] 5e80:                                     60000013 c01459c4 0000002a c06f8ef8
[   55.839956] 5ea0: db651000 c06f8ef8 daebac00 c04cb668 daebac08 c0346864 00000000 c01459c4
[   55.848115] 5ec0: d99eaa80 c06f8ef8 00000fff 00001000 db651000 c027f25c c027f240 d99eaa80
[   55.856274] 5ee0: d9a06c00 c0146218 daf55f18 00001000 d99eaa80 db4c18c0 00000001 00000001
[   55.864468] 5f00: daf55f80 c0144c78 c0144c54 c0107f90 00015000 d99eaab0 00000000 00000000
[   55.872603] 5f20: 000051c7 00000000 db4c18c0 c04a9370 00015000 00001000 daf55f80 00001000
[   55.880763] 5f40: daf54000 00015000 00000000 c00e53dc db4c18c0 c00e548c 0000000d 00008124
[   55.888937] 5f60: 00000001 00000000 00000000 db4c18c0 db4c18c0 00001000 00015000 c00e5550
[   55.897099] 5f80: 00000000 00000000 00001000 00001000 00015000 00000003 00000003 c000f364
[   55.905239] 5fa0: 00000000 c000f1a0 00001000 00015000 00000003 00015000 00001000 0001333c
[   55.913399] 5fc0: 00001000 00015000 00000003 00000003 00000002 00000000 00000000 00000000
[   55.921560] 5fe0: 7fffe000 be999850 0000a225 b6f3c19c 60000010 00000003 00000000 00000000
[   55.929744] [<c034b0b4>] (charger_get_property) from [<c0346864>] (power_supply_show_property+0x48/0x20c)
[   55.939286] [<c0346864>] (power_supply_show_property) from [<c027f25c>] (dev_attr_show+0x1c/0x48)
[   55.948130] [<c027f25c>] (dev_attr_show) from [<c0146218>] (sysfs_kf_seq_show+0x84/0x104)
[   55.956298] [<c0146218>] (sysfs_kf_seq_show) from [<c0144c78>] (kernfs_seq_show+0x24/0x28)
[   55.964536] [<c0144c78>] (kernfs_seq_show) from [<c0107f90>] (seq_read+0x1b0/0x484)
[   55.972172] [<c0107f90>] (seq_read) from [<c00e53dc>] (__vfs_read+0x18/0x4c)
[   55.979188] [<c00e53dc>] (__vfs_read) from [<c00e548c>] (vfs_read+0x7c/0x100)
[   55.986304] [<c00e548c>] (vfs_read) from [<c00e5550>] (SyS_read+0x40/0x8c)
[   55.993164] [<c00e5550>] (SyS_read) from [<c000f1a0>] (ret_fast_syscall+0x0/0x48)
[   56.000626] Code: bad PC value
[   56.011652] ---[ end trace 7b64343fbdae8ef1 ]---

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

[for the nvec part]
Reviewed-by: Marc Dietrich <marvin24@gmx.de>

[for compal-laptop.c]
Acked-by: Darren Hart <dvhart@linux.intel.com>

[for the mfd part]
Acked-by: Lee Jones <lee.jones@linaro.org>

[for the hid part]
Acked-by: Jiri Kosina <jkosina@suse.cz>

[for the acpi part]
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Signed-off-by: Sebastian Reichel <sre@kernel.org>

1 files changed, 159 insertions, 83 deletions

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 583dece8845b..e51405b176c8 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -40,16 +40,16 @@ static bool __power_supply_is_supplied_by(struct power_supply *supplier,
 
 	/* Support both supplied_to and supplied_from modes */
 	if (supply->supplied_from) {
-		if (!supplier->name)
+		if (!supplier->desc->name)
 			return false;
 		for (i = 0; i < supply->num_supplies; i++)
-			if (!strcmp(supplier->name, supply->supplied_from[i]))
+			if (!strcmp(supplier->desc->name, supply->supplied_from[i]))
 				return true;
 	} else {
-		if (!supply->name)
+		if (!supply->desc->name)
 			return false;
 		for (i = 0; i < supplier->num_supplicants; i++)
-			if (!strcmp(supplier->supplied_to[i], supply->name))
+			if (!strcmp(supplier->supplied_to[i], supply->desc->name))
 				return true;
 	}
 
@@ -62,8 +62,8 @@ static int __power_supply_changed_work(struct device *dev, void *data)
 	struct power_supply *pst = dev_get_drvdata(dev);
 
 	if (__power_supply_is_supplied_by(psy, pst)) {
-		if (pst->external_power_changed)
-			pst->external_power_changed(pst);
+		if (pst->desc->external_power_changed)
+			pst->desc->external_power_changed(pst);
 	}
 
 	return 0;
@@ -75,7 +75,7 @@ static void power_supply_changed_work(struct work_struct *work)
 	struct power_supply *psy = container_of(work, struct power_supply,
 						changed_work);
 
-	dev_dbg(psy->dev, "%s\n", __func__);
+	dev_dbg(&psy->dev, "%s\n", __func__);
 
 	spin_lock_irqsave(&psy->changed_lock, flags);
 	/*
@@ -93,7 +93,7 @@ static void power_supply_changed_work(struct work_struct *work)
 		power_supply_update_leds(psy);
 		atomic_notifier_call_chain(&power_supply_notifier,
 				PSY_EVENT_PROP_CHANGED, psy);
-		kobject_uevent(&psy->dev->kobj, KOBJ_CHANGE);
+		kobject_uevent(&psy->dev.kobj, KOBJ_CHANGE);
 		spin_lock_irqsave(&psy->changed_lock, flags);
 	}
 
@@ -103,7 +103,7 @@ static void power_supply_changed_work(struct work_struct *work)
 	 * to true.
 	 */
 	if (likely(!psy->changed))
-		pm_relax(psy->dev);
+		pm_relax(&psy->dev);
 	spin_unlock_irqrestore(&psy->changed_lock, flags);
 }
 
@@ -111,11 +111,11 @@ void power_supply_changed(struct power_supply *psy)
 {
 	unsigned long flags;
 
-	dev_dbg(psy->dev, "%s\n", __func__);
+	dev_dbg(&psy->dev, "%s\n", __func__);
 
 	spin_lock_irqsave(&psy->changed_lock, flags);
 	psy->changed = true;
-	pm_stay_awake(psy->dev);
+	pm_stay_awake(&psy->dev);
 	spin_unlock_irqrestore(&psy->changed_lock, flags);
 	schedule_work(&psy->changed_work);
 }
@@ -138,9 +138,9 @@ static int __power_supply_populate_supplied_from(struct device *dev,
 			break;
 
 		if (np == epsy->of_node) {
-			dev_info(psy->dev, "%s: Found supply : %s\n",
-				psy->name, epsy->name);
-			psy->supplied_from[i-1] = (char *)epsy->name;
+			dev_info(&psy->dev, "%s: Found supply : %s\n",
+				psy->desc->name, epsy->desc->name);
+			psy->supplied_from[i-1] = (char *)epsy->desc->name;
 			psy->num_supplies++;
 			of_node_put(np);
 			break;
@@ -158,7 +158,7 @@ static int power_supply_populate_supplied_from(struct power_supply *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);
+	dev_dbg(&psy->dev, "%s %d\n", __func__, error);
 
 	return error;
 }
@@ -220,7 +220,7 @@ static int power_supply_check_supplies(struct power_supply *psy)
 		of_node_put(np);
 
 		if (ret) {
-			dev_dbg(psy->dev, "Failed to find supply!\n");
+			dev_dbg(&psy->dev, "Failed to find supply!\n");
 			return ret;
 		}
 	} while (np);
@@ -230,17 +230,18 @@ static int power_supply_check_supplies(struct power_supply *psy)
 		return 0;
 
 	/* All supplies found, allocate char ** array for filling */
-	psy->supplied_from = devm_kzalloc(psy->dev, sizeof(psy->supplied_from),
+	psy->supplied_from = devm_kzalloc(&psy->dev, sizeof(psy->supplied_from),
 					  GFP_KERNEL);
 	if (!psy->supplied_from) {
-		dev_err(psy->dev, "Couldn't allocate memory for supply list\n");
+		dev_err(&psy->dev, "Couldn't allocate memory for supply list\n");
 		return -ENOMEM;
 	}
 
-	*psy->supplied_from = devm_kzalloc(psy->dev, sizeof(char *) * (cnt - 1),
+	*psy->supplied_from = devm_kzalloc(&psy->dev,
+					   sizeof(char *) * (cnt - 1),
 					   GFP_KERNEL);
 	if (!*psy->supplied_from) {
-		dev_err(psy->dev, "Couldn't allocate memory for supply list\n");
+		dev_err(&psy->dev, "Couldn't allocate memory for supply list\n");
 		return -ENOMEM;
 	}
 
@@ -260,7 +261,8 @@ static int __power_supply_am_i_supplied(struct device *dev, void *data)
 	struct power_supply *epsy = dev_get_drvdata(dev);
 
 	if (__power_supply_is_supplied_by(epsy, psy))
-		if (!epsy->get_property(epsy, POWER_SUPPLY_PROP_ONLINE, &ret))
+		if (!epsy->desc->get_property(epsy, POWER_SUPPLY_PROP_ONLINE,
+					&ret))
 			return ret.intval;
 
 	return 0;
@@ -273,7 +275,7 @@ int power_supply_am_i_supplied(struct power_supply *psy)
 	error = class_for_each_device(power_supply_class, NULL, psy,
 				      __power_supply_am_i_supplied);
 
-	dev_dbg(psy->dev, "%s %d\n", __func__, error);
+	dev_dbg(&psy->dev, "%s %d\n", __func__, error);
 
 	return error;
 }
@@ -286,8 +288,9 @@ static int __power_supply_is_system_supplied(struct device *dev, void *data)
 	unsigned int *count = data;
 
 	(*count)++;
-	if (psy->type != POWER_SUPPLY_TYPE_BATTERY)
-		if (!psy->get_property(psy, POWER_SUPPLY_PROP_ONLINE, &ret))
+	if (psy->desc->type != POWER_SUPPLY_TYPE_BATTERY)
+		if (!psy->desc->get_property(psy, POWER_SUPPLY_PROP_ONLINE,
+					&ret))
 			return ret.intval;
 
 	return 0;
@@ -315,9 +318,9 @@ EXPORT_SYMBOL_GPL(power_supply_is_system_supplied);
 int power_supply_set_battery_charged(struct power_supply *psy)
 {
 	if (atomic_read(&psy->use_cnt) >= 0 &&
-			psy->type == POWER_SUPPLY_TYPE_BATTERY &&
-			psy->set_charged) {
-		psy->set_charged(psy);
+			psy->desc->type == POWER_SUPPLY_TYPE_BATTERY &&
+			psy->desc->set_charged) {
+		psy->desc->set_charged(psy);
 		return 0;
 	}
 
@@ -330,7 +333,7 @@ static int power_supply_match_device_by_name(struct device *dev, const void *dat
 	const char *name = data;
 	struct power_supply *psy = dev_get_drvdata(dev);
 
-	return strcmp(psy->name, name) == 0;
+	return strcmp(psy->desc->name, name) == 0;
 }
 
 struct power_supply *power_supply_get_by_name(const char *name)
@@ -375,7 +378,7 @@ int power_supply_get_property(struct power_supply *psy,
 	if (atomic_read(&psy->use_cnt) <= 0)
 		return -ENODEV;
 
-	return psy->get_property(psy, psp, val);
+	return psy->desc->get_property(psy, psp, val);
 }
 EXPORT_SYMBOL_GPL(power_supply_get_property);
 
@@ -383,42 +386,45 @@ int power_supply_set_property(struct power_supply *psy,
 			    enum power_supply_property psp,
 			    const union power_supply_propval *val)
 {
-	if (atomic_read(&psy->use_cnt) <= 0 || !psy->set_property)
+	if (atomic_read(&psy->use_cnt) <= 0 || !psy->desc->set_property)
 		return -ENODEV;
 
-	return psy->set_property(psy, psp, val);
+	return psy->desc->set_property(psy, psp, val);
 }
 EXPORT_SYMBOL_GPL(power_supply_set_property);
 
 int power_supply_property_is_writeable(struct power_supply *psy,
 					enum power_supply_property psp)
 {
-	if (atomic_read(&psy->use_cnt) <= 0 || !psy->property_is_writeable)
+	if (atomic_read(&psy->use_cnt) <= 0 ||
+			!psy->desc->property_is_writeable)
 		return -ENODEV;
 
-	return psy->property_is_writeable(psy, psp);
+	return psy->desc->property_is_writeable(psy, psp);
 }
 EXPORT_SYMBOL_GPL(power_supply_property_is_writeable);
 
 void power_supply_external_power_changed(struct power_supply *psy)
 {
-	if (atomic_read(&psy->use_cnt) <= 0 || !psy->external_power_changed)
+	if (atomic_read(&psy->use_cnt) <= 0 ||
+			!psy->desc->external_power_changed)
 		return;
 
-	psy->external_power_changed(psy);
+	psy->desc->external_power_changed(psy);
 }
 EXPORT_SYMBOL_GPL(power_supply_external_power_changed);
 
 int power_supply_powers(struct power_supply *psy, struct device *dev)
 {
-	return sysfs_create_link(&psy->dev->kobj, &dev->kobj, "powers");
+	return sysfs_create_link(&psy->dev.kobj, &dev->kobj, "powers");
 }
 EXPORT_SYMBOL_GPL(power_supply_powers);
 
 static void power_supply_dev_release(struct device *dev)
 {
+	struct power_supply *psy = container_of(dev, struct power_supply, dev);
 	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
-	kfree(dev);
+	kfree(psy);
 }
 
 int power_supply_reg_notifier(struct notifier_block *nb)
@@ -443,7 +449,7 @@ static int power_supply_read_temp(struct thermal_zone_device *tzd,
 
 	WARN_ON(tzd == NULL);
 	psy = tzd->devdata;
-	ret = psy->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
+	ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val);
 
 	/* Convert tenths of degree Celsius to milli degree Celsius. */
 	if (!ret)
@@ -460,14 +466,14 @@ static int psy_register_thermal(struct power_supply *psy)
 {
 	int i;
 
-	if (psy->no_thermal)
+	if (psy->desc->no_thermal)
 		return 0;
 
 	/* Register battery zone device psy reports temperature */
-	for (i = 0; i < psy->num_properties; i++) {
-		if (psy->properties[i] == POWER_SUPPLY_PROP_TEMP) {
-			psy->tzd = thermal_zone_device_register(psy->name, 0, 0,
-					psy, &psy_tzd_ops, NULL, 0, 0);
+	for (i = 0; i < psy->desc->num_properties; i++) {
+		if (psy->desc->properties[i] == POWER_SUPPLY_PROP_TEMP) {
+			psy->tzd = thermal_zone_device_register(psy->desc->name,
+					0, 0, psy, &psy_tzd_ops, NULL, 0, 0);
 			return PTR_ERR_OR_ZERO(psy->tzd);
 		}
 	}
@@ -490,7 +496,7 @@ static int ps_get_max_charge_cntl_limit(struct thermal_cooling_device *tcd,
 	int ret;
 
 	psy = tcd->devdata;
-	ret = psy->get_property(psy,
+	ret = psy->desc->get_property(psy,
 		POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, &val);
 	if (!ret)
 		*state = val.intval;
@@ -506,7 +512,7 @@ static int ps_get_cur_chrage_cntl_limit(struct thermal_cooling_device *tcd,
 	int ret;
 
 	psy = tcd->devdata;
-	ret = psy->get_property(psy,
+	ret = psy->desc->get_property(psy,
 		POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT, &val);
 	if (!ret)
 		*state = val.intval;
@@ -523,7 +529,7 @@ static int ps_set_cur_charge_cntl_limit(struct thermal_cooling_device *tcd,
 
 	psy = tcd->devdata;
 	val.intval = state;
-	ret = psy->set_property(psy,
+	ret = psy->desc->set_property(psy,
 		POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT, &val);
 
 	return ret;
@@ -540,11 +546,11 @@ static int psy_register_cooler(struct power_supply *psy)
 	int i;
 
 	/* Register for cooling device if psy can control charging */
-	for (i = 0; i < psy->num_properties; i++) {
-		if (psy->properties[i] ==
+	for (i = 0; i < psy->desc->num_properties; i++) {
+		if (psy->desc->properties[i] ==
 				POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT) {
 			psy->tcd = thermal_cooling_device_register(
-							(char *)psy->name,
+							(char *)psy->desc->name,
 							psy, &psy_tcd_ops);
 			return PTR_ERR_OR_ZERO(psy->tcd);
 		}
@@ -578,17 +584,21 @@ static void psy_unregister_cooler(struct power_supply *psy)
 }
 #endif
 
-static int __power_supply_register(struct device *parent,
-				   struct power_supply *psy,
+static struct power_supply *__must_check
+__power_supply_register(struct device *parent,
+				   const struct power_supply_desc *desc,
 				   const struct power_supply_config *cfg,
 				   bool ws)
 {
 	struct device *dev;
+	struct power_supply *psy;
 	int rc;
 
-	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-	if (!dev)
-		return -ENOMEM;
+	psy = kzalloc(sizeof(*psy), GFP_KERNEL);
+	if (!psy)
+		return ERR_PTR(-ENOMEM);
+
+	dev = &psy->dev;
 
 	device_initialize(dev);
 
@@ -597,7 +607,7 @@ static int __power_supply_register(struct device *parent,
 	dev->parent = parent;
 	dev->release = power_supply_dev_release;
 	dev_set_drvdata(dev, psy);
-	psy->dev = dev;
+	psy->desc = desc;
 	atomic_inc(&psy->use_cnt);
 	if (cfg) {
 		psy->drv_data = cfg->drv_data;
@@ -606,7 +616,7 @@ static int __power_supply_register(struct device *parent,
 		psy->num_supplicants = cfg->num_supplicants;
 	}
 
-	rc = dev_set_name(dev, "%s", psy->name);
+	rc = dev_set_name(dev, "%s", desc->name);
 	if (rc)
 		goto dev_set_name_failed;
 
@@ -641,7 +651,7 @@ static int __power_supply_register(struct device *parent,
 
 	power_supply_changed(psy);
 
-	return 0;
+	return psy;
 
 create_triggers_failed:
 	psy_unregister_cooler(psy);
@@ -654,20 +664,49 @@ wakeup_init_failed:
 check_supplies_failed:
 dev_set_name_failed:
 	put_device(dev);
-	return rc;
+	return ERR_PTR(rc);
 }
 
-int power_supply_register(struct device *parent, struct power_supply *psy,
+/**
+ * power_supply_register() - Register new power supply
+ * @parent:	Device to be a parent of power supply's device
+ * @desc:	Description of power supply, must be valid through whole
+ *		lifetime of this power supply
+ * @cfg:	Run-time specific configuration accessed during registering,
+ *		may be NULL
+ *
+ * Return: A pointer to newly allocated power_supply on success
+ * or ERR_PTR otherwise.
+ * Use power_supply_unregister() on returned power_supply pointer to release
+ * resources.
+ */
+struct power_supply *__must_check power_supply_register(struct device *parent,
+		const struct power_supply_desc *desc,
 		const struct power_supply_config *cfg)
 {
-	return __power_supply_register(parent, psy, cfg, true);
+	return __power_supply_register(parent, desc, cfg, true);
 }
 EXPORT_SYMBOL_GPL(power_supply_register);
 
-int power_supply_register_no_ws(struct device *parent, struct power_supply *psy,
+/**
+ * power_supply_register() - Register new non-waking-source power supply
+ * @parent:	Device to be a parent of power supply's device
+ * @desc:	Description of power supply, must be valid through whole
+ *		lifetime of this power supply
+ * @cfg:	Run-time specific configuration accessed during registering,
+ *		may be NULL
+ *
+ * Return: A pointer to newly allocated power_supply on success
+ * or ERR_PTR otherwise.
+ * Use power_supply_unregister() on returned power_supply pointer to release
+ * resources.
+ */
+struct power_supply *__must_check
+power_supply_register_no_ws(struct device *parent,
+		const struct power_supply_desc *desc,
 		const struct power_supply_config *cfg)
 {
-	return __power_supply_register(parent, psy, cfg, false);
+	return __power_supply_register(parent, desc, cfg, false);
 }
 EXPORT_SYMBOL_GPL(power_supply_register_no_ws);
 
@@ -678,56 +717,93 @@ static void devm_power_supply_release(struct device *dev, void *res)
 	power_supply_unregister(*psy);
 }
 
-int devm_power_supply_register(struct device *parent, struct power_supply *psy,
+/**
+ * power_supply_register() - Register managed power supply
+ * @parent:	Device to be a parent of power supply's device
+ * @desc:	Description of power supply, must be valid through whole
+ *		lifetime of this power supply
+ * @cfg:	Run-time specific configuration accessed during registering,
+ *		may be NULL
+ *
+ * Return: A pointer to newly allocated power_supply on success
+ * or ERR_PTR otherwise.
+ * The returned power_supply pointer will be automatically unregistered
+ * on driver detach.
+ */
+struct power_supply *__must_check
+devm_power_supply_register(struct device *parent,
+		const struct power_supply_desc *desc,
 		const struct power_supply_config *cfg)
 {
-	struct power_supply **ptr = devres_alloc(devm_power_supply_release,
-						 sizeof(*ptr), GFP_KERNEL);
-	int ret;
+	struct power_supply **ptr, *psy;
+
+	ptr = devres_alloc(devm_power_supply_release, sizeof(*ptr), GFP_KERNEL);
 
 	if (!ptr)
-		return -ENOMEM;
-	ret = __power_supply_register(parent, psy, cfg, true);
-	if (ret < 0)
+		return ERR_PTR(-ENOMEM);
+	psy = __power_supply_register(parent, desc, cfg, true);
+	if (IS_ERR(psy)) {
 		devres_free(ptr);
-	else {
+	} else {
 		*ptr = psy;
 		devres_add(parent, ptr);
 	}
-	return ret;
+	return psy;
 }
 EXPORT_SYMBOL_GPL(devm_power_supply_register);
 
-int devm_power_supply_register_no_ws(struct device *parent, struct power_supply *psy,
+/**
+ * power_supply_register() - Register managed non-waking-source power supply
+ * @parent:	Device to be a parent of power supply's device
+ * @desc:	Description of power supply, must be valid through whole
+ *		lifetime of this power supply
+ * @cfg:	Run-time specific configuration accessed during registering,
+ *		may be NULL
+ *
+ * Return: A pointer to newly allocated power_supply on success
+ * or ERR_PTR otherwise.
+ * The returned power_supply pointer will be automatically unregistered
+ * on driver detach.
+ */
+struct power_supply *__must_check
+devm_power_supply_register_no_ws(struct device *parent,
+		const struct power_supply_desc *desc,
 		const struct power_supply_config *cfg)
 {
-	struct power_supply **ptr = devres_alloc(devm_power_supply_release,
-						 sizeof(*ptr), GFP_KERNEL);
-	int ret;
+	struct power_supply **ptr, *psy;
+
+	ptr = devres_alloc(devm_power_supply_release, sizeof(*ptr), GFP_KERNEL);
 
 	if (!ptr)
-		return -ENOMEM;
-	ret = __power_supply_register(parent, psy, cfg, false);
-	if (ret < 0)
+		return ERR_PTR(-ENOMEM);
+	psy = __power_supply_register(parent, desc, cfg, false);
+	if (IS_ERR(psy)) {
 		devres_free(ptr);
-	else {
+	} else {
 		*ptr = psy;
 		devres_add(parent, ptr);
 	}
-	return ret;
+	return psy;
 }
 EXPORT_SYMBOL_GPL(devm_power_supply_register_no_ws);
 
+/**
+ * power_supply_unregister() - Remove this power supply from system
+ * @psy:	Pointer to power supply to unregister
+ *
+ * Remove this power supply from the system. The resources of power supply
+ * will be freed here or on last power_supply_put() call.
+ */
 void power_supply_unregister(struct power_supply *psy)
 {
 	WARN_ON(atomic_dec_return(&psy->use_cnt));
 	cancel_work_sync(&psy->changed_work);
-	sysfs_remove_link(&psy->dev->kobj, "powers");
+	sysfs_remove_link(&psy->dev.kobj, "powers");
 	power_supply_remove_triggers(psy);
 	psy_unregister_cooler(psy);
 	psy_unregister_thermal(psy);
-	device_init_wakeup(psy->dev, false);
-	device_unregister(psy->dev);
+	device_init_wakeup(&psy->dev, false);
+	device_unregister(&psy->dev);
 }
 EXPORT_SYMBOL_GPL(power_supply_unregister);