Commit 6037802b authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Sebastian Reichel
Browse files

power: supply: core: implement extension API 



Various drivers, mostly in platform/x86 extend the ACPI battery driver
with additional sysfs attributes to implement more UAPIs than are
exposed through ACPI by using various side-channels, like WMI,
nonstandard ACPI or EC communication.

While the created sysfs attributes look similar to the attributes
provided by the powersupply core, there are various deficiencies:

* They don't show up in uevent payload.
* They can't be queried with the standard in-kernel APIs.
* They don't work with triggers.
* The extending driver has to reimplement all of the parsing,
formatting and sysfs display logic.
* Writing a extension driver is completely different from writing a
normal power supply driver.

This extension API avoids all of these issues.
An extension is just a "struct power_supply_ext" with the same kind of
callbacks as in a normal "struct power_supply_desc".

The API is meant to be used via battery_hook_register(), the same way as
the current extensions.

Signed-off-by: default avatarThomas Weißschuh <linux@weissschuh.net>
Reviewed-by: default avatarArmin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20241211-power-supply-extensions-v6-1-9d9dc3f3d387@weissschuh.net


Signed-off-by: default avatarSebastian Reichel <sebastian.reichel@collabora.com>
parent 57e5a9a8

drivers/power/supply/power_supply.h

+17 −0
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 
 *  Modified: 2004, Oct     Szabolcs Gyurko

 */



#include <linux/lockdep.h>



struct device;

struct device_type;

struct power_supply;
@@ -17,6 +19,21 @@ extern int power_supply_property_is_writeable(struct power_supply *psy, 
					      enum power_supply_property psp);

extern bool power_supply_has_property(struct power_supply *psy,

				      enum power_supply_property psp);

extern bool power_supply_ext_has_property(const struct power_supply_ext *ext,

					  enum power_supply_property psp);



struct power_supply_ext_registration {

	struct list_head list_head;

	const struct power_supply_ext *ext;

	void *data;

};



/* Make sure that the macro is a single expression */

#define power_supply_for_each_extension(pos, psy)			\

	if ( ({ lockdep_assert_held(&(psy)->extensions_sem); 0; }) )	\

		;							\

	else								\

		list_for_each_entry(pos, &(psy)->extensions, list_head)	\



#ifdef CONFIG_SYSFS

drivers/power/supply/power_supply_core.c

+154 −8
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ static int __power_supply_changed_work(struct power_supply *pst, void *data) 


static void power_supply_changed_work(struct work_struct *work)

{

	int ret;

	unsigned long flags;

	struct power_supply *psy = container_of(work, struct power_supply,

						changed_work);
@@ -87,6 +88,16 @@ static void power_supply_changed_work(struct work_struct *work) 
	dev_dbg(&psy->dev, "%s\n", __func__);



	spin_lock_irqsave(&psy->changed_lock, flags);



	if (unlikely(psy->update_groups)) {

		psy->update_groups = false;

		spin_unlock_irqrestore(&psy->changed_lock, flags);

		ret = sysfs_update_groups(&psy->dev.kobj, power_supply_dev_type.groups);

		if (ret)

			dev_warn(&psy->dev, "failed to update sysfs groups: %pe\n", ERR_PTR(ret));

		spin_lock_irqsave(&psy->changed_lock, flags);

	}



	/*

	 * Check 'changed' here to avoid issues due to race between

	 * power_supply_changed() and this routine. In worst case
@@ -1208,15 +1219,34 @@ static bool psy_desc_has_property(const struct power_supply_desc *psy_desc, 
	return found;

}



bool power_supply_ext_has_property(const struct power_supply_ext *psy_ext,

				   enum power_supply_property psp)

{

	int i;



	for (i = 0; i < psy_ext->num_properties; i++)

		if (psy_ext->properties[i] == psp)

			return true;



	return false;

}



bool power_supply_has_property(struct power_supply *psy,

			       enum power_supply_property psp)

{

	struct power_supply_ext_registration *reg;



	if (psy_desc_has_property(psy->desc, psp))

		return true;



	if (power_supply_battery_info_has_prop(psy->battery_info, psp))

		return true;



	power_supply_for_each_extension(reg, psy) {

		if (power_supply_ext_has_property(reg->ext, psp))

			return true;

	}



	return false;

}
@@ -1224,12 +1254,21 @@ int power_supply_get_property(struct power_supply *psy, 
			    enum power_supply_property psp,

			    union power_supply_propval *val)

{

	struct power_supply_ext_registration *reg;



	if (atomic_read(&psy->use_cnt) <= 0) {

		if (!psy->initialized)

			return -EAGAIN;

		return -ENODEV;

	}



	scoped_guard(rwsem_read, &psy->extensions_sem) {

		power_supply_for_each_extension(reg, psy) {

			if (power_supply_ext_has_property(reg->ext, psp))

				return reg->ext->get_property(psy, reg->ext, reg->data, psp, val);

		}

	}



	if (psy_desc_has_property(psy->desc, psp))

		return psy->desc->get_property(psy, psp, val);

	else if (power_supply_battery_info_has_prop(psy->battery_info, psp))
@@ -1243,7 +1282,24 @@ 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->desc->set_property)

	struct power_supply_ext_registration *reg;



	if (atomic_read(&psy->use_cnt) <= 0)

		return -ENODEV;



	scoped_guard(rwsem_read, &psy->extensions_sem) {

		power_supply_for_each_extension(reg, psy) {

			if (power_supply_ext_has_property(reg->ext, psp)) {

				if (reg->ext->set_property)

					return reg->ext->set_property(psy, reg->ext, reg->data,

								      psp, val);

				else

					return -ENODEV;

			}

		}

	}



	if (!psy->desc->set_property)

		return -ENODEV;



	return psy->desc->set_property(psy, psp, val);
@@ -1253,7 +1309,22 @@ EXPORT_SYMBOL_GPL(power_supply_set_property); 
int power_supply_property_is_writeable(struct power_supply *psy,

					enum power_supply_property psp)

{

	return psy->desc->property_is_writeable && psy->desc->property_is_writeable(psy, psp);

	struct power_supply_ext_registration *reg;



	power_supply_for_each_extension(reg, psy) {

		if (power_supply_ext_has_property(reg->ext, psp)) {

			if (reg->ext->property_is_writeable)

				return reg->ext->property_is_writeable(psy, reg->ext,

								       reg->data, psp);

			else

				return 0;

		}

	}



	if (!psy->desc->property_is_writeable)

		return 0;



	return psy->desc->property_is_writeable(psy, psp);

}



void power_supply_external_power_changed(struct power_supply *psy)
@@ -1272,6 +1343,76 @@ int power_supply_powers(struct power_supply *psy, struct device *dev) 
}

EXPORT_SYMBOL_GPL(power_supply_powers);



static int power_supply_update_sysfs_and_hwmon(struct power_supply *psy)

{

	unsigned long flags;



	spin_lock_irqsave(&psy->changed_lock, flags);

	psy->update_groups = true;

	spin_unlock_irqrestore(&psy->changed_lock, flags);



	power_supply_changed(psy);



	power_supply_remove_hwmon_sysfs(psy);

	return power_supply_add_hwmon_sysfs(psy);

}



int power_supply_register_extension(struct power_supply *psy, const struct power_supply_ext *ext,

				    void *data)

{

	struct power_supply_ext_registration *reg;

	size_t i;

	int ret;



	if (!psy || !ext || !ext->properties || !ext->num_properties)

		return -EINVAL;



	guard(rwsem_write)(&psy->extensions_sem);



	for (i = 0; i < ext->num_properties; i++)

		if (power_supply_has_property(psy, ext->properties[i]))

			return -EEXIST;



	reg = kmalloc(sizeof(*reg), GFP_KERNEL);

	if (!reg)

		return -ENOMEM;



	reg->ext = ext;

	reg->data = data;

	list_add(&reg->list_head, &psy->extensions);



	ret = power_supply_update_sysfs_and_hwmon(psy);

	if (ret)

		goto sysfs_hwmon_failed;



	return 0;



sysfs_hwmon_failed:

	list_del(&reg->list_head);

	kfree(reg);

	return ret;

}

EXPORT_SYMBOL_GPL(power_supply_register_extension);



void power_supply_unregister_extension(struct power_supply *psy, const struct power_supply_ext *ext)

{

	struct power_supply_ext_registration *reg;



	guard(rwsem_write)(&psy->extensions_sem);



	power_supply_for_each_extension(reg, psy) {

		if (reg->ext == ext) {

			list_del(&reg->list_head);

			kfree(reg);

			power_supply_update_sysfs_and_hwmon(psy);

			return;

		}

	}



	dev_warn(&psy->dev, "Trying to unregister invalid extension");

}

EXPORT_SYMBOL_GPL(power_supply_unregister_extension);



static void power_supply_dev_release(struct device *dev)

{

	struct power_supply *psy = to_power_supply(dev);
@@ -1426,6 +1567,9 @@ __power_supply_register(struct device *parent, 
	}



	spin_lock_init(&psy->changed_lock);

	init_rwsem(&psy->extensions_sem);

	INIT_LIST_HEAD(&psy->extensions);



	rc = device_add(dev);

	if (rc)

		goto device_add_failed;
@@ -1438,6 +1582,7 @@ __power_supply_register(struct device *parent, 
	if (rc)

		goto register_thermal_failed;



	scoped_guard(rwsem_read, &psy->extensions_sem) {

		rc = power_supply_create_triggers(psy);

		if (rc)

			goto create_triggers_failed;
@@ -1445,6 +1590,7 @@ __power_supply_register(struct device *parent, 
		rc = power_supply_add_hwmon_sysfs(psy);

		if (rc)

			goto add_hwmon_sysfs_failed;

	}



	/*

	 * Update use_cnt after any uevents (most notably from device_add()).

drivers/power/supply/power_supply_sysfs.c

+24 −2
Original line number Diff line number Diff line
@@ -299,6 +299,27 @@ static ssize_t power_supply_show_enum_with_available( 
	return count;

}



static ssize_t power_supply_show_charge_behaviour(struct device *dev,

						  struct power_supply *psy,

						  union power_supply_propval *value,

						  char *buf)

{

	struct power_supply_ext_registration *reg;



	scoped_guard(rwsem_read, &psy->extensions_sem) {

		power_supply_for_each_extension(reg, psy) {

			if (power_supply_ext_has_property(reg->ext,

							  POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR))

				return power_supply_charge_behaviour_show(dev,

						reg->ext->charge_behaviours,

						value->intval, buf);

		}

	}



	return power_supply_charge_behaviour_show(dev, psy->desc->charge_behaviours,

						  value->intval, buf);

}



static ssize_t power_supply_format_property(struct device *dev,

					    bool uevent,

					    struct device_attribute *attr,
@@ -338,8 +359,7 @@ static ssize_t power_supply_format_property(struct device *dev, 
	case POWER_SUPPLY_PROP_CHARGE_BEHAVIOUR:

		if (uevent) /* no possible values in uevents */

			goto default_format;

		ret = power_supply_charge_behaviour_show(dev, psy->desc->charge_behaviours,

							 value.intval, buf);

		ret = power_supply_show_charge_behaviour(dev, psy, &value, buf);

		break;

	case POWER_SUPPLY_PROP_CHARGE_TYPES:

		if (uevent) /* no possible values in uevents */
@@ -422,6 +442,8 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj, 
	if (attrno == POWER_SUPPLY_PROP_TYPE)

		return mode;



	guard(rwsem_read)(&psy->extensions_sem);



	if (power_supply_has_property(psy, attrno)) {

		if (power_supply_property_is_writeable(psy, attrno) > 0)

			mode |= S_IWUSR;

include/linux/power_supply.h

+33 −0
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ 
#include <linux/device.h>

#include <linux/workqueue.h>

#include <linux/leds.h>

#include <linux/rwsem.h>

#include <linux/list.h>

#include <linux/spinlock.h>

#include <linux/notifier.h>
@@ -283,6 +285,27 @@ struct power_supply_desc { 
	int use_for_apm;

};



struct power_supply_ext {

	u8 charge_behaviours;

	const enum power_supply_property *properties;

	size_t num_properties;



	int (*get_property)(struct power_supply *psy,

			    const struct power_supply_ext *ext,

			    void *data,

			    enum power_supply_property psp,

			    union power_supply_propval *val);

	int (*set_property)(struct power_supply *psy,

			    const struct power_supply_ext *ext,

			    void *data,

			    enum power_supply_property psp,

			    const union power_supply_propval *val);

	int (*property_is_writeable)(struct power_supply *psy,

				     const struct power_supply_ext *ext,

				     void *data,

				     enum power_supply_property psp);

};



struct power_supply {

	const struct power_supply_desc *desc;
@@ -302,10 +325,13 @@ struct power_supply { 
	struct delayed_work deferred_register_work;

	spinlock_t changed_lock;

	bool changed;

	bool update_groups;

	bool initialized;

	bool removing;

	atomic_t use_cnt;

	struct power_supply_battery_info *battery_info;

	struct rw_semaphore extensions_sem; /* protects "extensions" */

	struct list_head extensions;

#ifdef CONFIG_THERMAL

	struct thermal_zone_device *tzd;

	struct thermal_cooling_device *tcd;
@@ -882,6 +908,13 @@ devm_power_supply_register(struct device *parent, 
extern void power_supply_unregister(struct power_supply *psy);

extern int power_supply_powers(struct power_supply *psy, struct device *dev);



extern int __must_check

power_supply_register_extension(struct power_supply *psy,

				const struct power_supply_ext *ext,

				void *data);

extern void power_supply_unregister_extension(struct power_supply *psy,

					      const struct power_supply_ext *ext);



#define to_power_supply(device) container_of(device, struct power_supply, dev)



extern void *power_supply_get_drvdata(struct power_supply *psy);