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Commit 74c5d09b authored by Donggeun Kim's avatar Donggeun Kim Committed by Greg Kroah-Hartman
Browse files

Extcon: support notification based on the state changes. 



State changes of extcon devices have been notified via kobjet_uevent.
This patch adds notifier interfaces in order to allow device drivers to
get notified easily. Along with notifier interface,
extcon_get_extcon_dev() function is added so that device drivers may
discover a extcon_dev easily.

Signed-off-by: default avatarDonggeun Kim <dg77.kim@samsung.com>
Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>

--
Changes from RFC
- Renamed switch to extcon
- Bugfix: extcon_dev_unregister()
- Bugfix: "edev->dev" is "internal" data.
- Added kerneldoc comments.
- Reworded comments.
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent be48308a

drivers/extcon/extcon_class.c

+66 −0
Original line number Diff line number Diff line
@@ -36,6 +36,9 @@ struct class *extcon_class; 
static struct class_compat *switch_class;

#endif /* CONFIG_ANDROID && !defined(CONFIG_ANDROID_SWITCH) */



static LIST_HEAD(extcon_dev_list);

static DEFINE_MUTEX(extcon_dev_list_lock);



static ssize_t state_show(struct device *dev, struct device_attribute *attr,

			  char *buf)

{
@@ -75,6 +78,9 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr, 
 * the name of extcon device (envp[0]) and the state output (envp[1]).

 * Tizen uses this format for extcon device to get events from ports.

 * Android uses this format as well.

 *

 * Note that notifier provides the which bits are changes in the state

 * variable with "val" to the callback.

 */

void extcon_set_state(struct extcon_dev *edev, u32 state)

{
@@ -84,10 +90,14 @@ void extcon_set_state(struct extcon_dev *edev, u32 state) 
	char *envp[3];

	int env_offset = 0;

	int length;

	u32 old_state = edev->state;



	if (edev->state != state) {

		edev->state = state;



		raw_notifier_call_chain(&edev->nh, old_state ^ edev->state,

					edev);



		prop_buf = (char *)get_zeroed_page(GFP_KERNEL);

		if (prop_buf) {

			length = name_show(edev->dev, NULL, prop_buf);
@@ -117,6 +127,51 @@ void extcon_set_state(struct extcon_dev *edev, u32 state) 
}

EXPORT_SYMBOL_GPL(extcon_set_state);



/**

 * extcon_get_extcon_dev() - Get the extcon device instance from the name

 * @extcon_name:	The extcon name provided with extcon_dev_register()

 */

struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)

{

	struct extcon_dev *sd;



	mutex_lock(&extcon_dev_list_lock);

	list_for_each_entry(sd, &extcon_dev_list, entry) {

		if (!strcmp(sd->name, extcon_name))

			goto out;

	}

	sd = NULL;

out:

	mutex_unlock(&extcon_dev_list_lock);

	return sd;

}

EXPORT_SYMBOL_GPL(extcon_get_extcon_dev);



/**

 * extcon_register_notifier() - Register a notifee to get notified by

 *			      any attach status changes from the extcon.

 * @edev:	the extcon device.

 * @nb:		a notifier block to be registered.

 */

int extcon_register_notifier(struct extcon_dev *edev,

			struct notifier_block *nb)

{

	return raw_notifier_chain_register(&edev->nh, nb);

}

EXPORT_SYMBOL_GPL(extcon_register_notifier);



/**

 * extcon_unregister_notifier() - Unregister a notifee from the extcon device.

 * @edev:	the extcon device.

 * @nb:		a registered notifier block to be unregistered.

 */

int extcon_unregister_notifier(struct extcon_dev *edev,

			struct notifier_block *nb)

{

	return raw_notifier_chain_unregister(&edev->nh, nb);

}

EXPORT_SYMBOL_GPL(extcon_unregister_notifier);



static struct device_attribute extcon_attrs[] = {

	__ATTR_RO(state),

	__ATTR_RO(name),
@@ -142,6 +197,10 @@ static int create_extcon_class(void) 


static void extcon_cleanup(struct extcon_dev *edev, bool skip)

{

	mutex_lock(&extcon_dev_list_lock);

	list_del(&edev->entry);

	mutex_unlock(&extcon_dev_list_lock);



	if (!skip && get_device(edev->dev)) {

		device_unregister(edev->dev);

		put_device(edev->dev);
@@ -194,8 +253,15 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev) 
					       dev);

#endif /* CONFIG_ANDROID && !defined(CONFIG_ANDROID_SWITCH) */



	RAW_INIT_NOTIFIER_HEAD(&edev->nh);



	dev_set_drvdata(edev->dev, edev);

	edev->state = 0;



	mutex_lock(&extcon_dev_list_lock);

	list_add(&edev->entry, &extcon_dev_list);

	mutex_unlock(&extcon_dev_list_lock);



	return 0;



err_dev:

include/linux/extcon.h

+38 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#ifndef __LINUX_EXTCON_H__

#define __LINUX_EXTCON_H__



#include <linux/notifier.h>

/**

 * struct extcon_dev - An extcon device represents one external connector.

 * @name	The name of this extcon device. Parent device name is used
@@ -34,6 +35,9 @@ 
 * @dev		Device of this extcon. Do not provide at register-time.

 * @state	Attach/detach state of this extcon. Do not provide at

 *		register-time

 * @nh	Notifier for the state change events from this extcon

 * @entry	To support list of extcon devices so that uses can search

 *		for extcon devices based on the extcon name.

 *

 * In most cases, users only need to provide "User initializing data" of

 * this struct when registering an extcon. In some exceptional cases,
@@ -51,11 +55,19 @@ struct extcon_dev { 
	/* --- Internal data. Please do not set. --- */

	struct device	*dev;

	u32		state;

	struct raw_notifier_head nh;

	struct list_head entry;

};



#if IS_ENABLED(CONFIG_EXTCON)



/*

 * Following APIs are for notifiers or configurations.

 * Notifiers are the external port and connection devices.

 */

extern int extcon_dev_register(struct extcon_dev *edev, struct device *dev);

extern void extcon_dev_unregister(struct extcon_dev *edev);

extern struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name);



static inline u32 extcon_get_state(struct extcon_dev *edev)

{
@@ -63,6 +75,15 @@ static inline u32 extcon_get_state(struct extcon_dev *edev) 
}



extern void extcon_set_state(struct extcon_dev *edev, u32 state);



/*

 * Following APIs are to monitor every action of a notifier.

 * Registerer gets notified for every external port of a connection device.

 */

extern int extcon_register_notifier(struct extcon_dev *edev,

				    struct notifier_block *nb);

extern int extcon_unregister_notifier(struct extcon_dev *edev,

				      struct notifier_block *nb);

#else /* CONFIG_EXTCON */

static inline int extcon_dev_register(struct extcon_dev *edev,

				      struct device *dev)
@@ -78,5 +99,22 @@ static inline u32 extcon_get_state(struct extcon_dev *edev) 
}



static inline void extcon_set_state(struct extcon_dev *edev, u32 state) { }

static inline struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)

{

	return NULL;

}



static inline int extcon_register_notifier(struct extcon_dev *edev,

					   struct notifier_block *nb)

{

	return 0;

}



static inline int extcon_unregister_notifier(struct extcon_dev *edev,

					     struct notifier_block *nb)

{

	return 0;

}



#endif /* CONFIG_EXTCON */

#endif /* __LINUX_EXTCON_H__ */