extcon: Add the synchronization extcon APIs to support the notification

This patch adds the synchronization extcon APIs to support the notifications
for both state and property. When extcon_*_sync() functions is called,
the extcon informs the information from extcon provider to extcon client.

The extcon driver may need to change the both state and multiple properties
at the same time. After setting the data of a external connector,
the extcon send the notification to client driver with the extcon_*_sync().

The list of new extcon APIs as following:
- extcon_sync() : Send the notification for each external connector to
		synchronize the information between extcon provider driver
		and extcon client driver.
- extcon_set_state_sync() : Set the state of external connector with noti.
- extcon_set_property_sync() : Set the property of external connector with noti.

For example,
case 1, change the state of external connector and synchronized the data.
	extcon_set_state_sync(edev, EXTCON_USB, 1);

case 2, change both the state and property of external connector
	and synchronized the data.
	extcon_set_state(edev, EXTCON_USB, 1);
	extcon_set_property(edev, EXTCON_USB, EXTCON_PROP_USB_VBUS 1);
	extcon_sync(edev, EXTCON_USB);

case 3, change the property of external connector and synchronized the data.
	extcon_set_property(edev, EXTCON_USB, EXTCON_PROP_USB_VBUS, 0);
	extcon_sync(edev, EXTCON_USB);

case 4, change the property of external connector and synchronized the data.
	extcon_set_property_sync(edev, EXTCON_USB, EXTCON_PROP_USB_VBUS, 0);

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Chris Zhong <zyw@rock-chips.com>
Tested-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>

drivers/extcon/extcon.c

@@ -279,14 +279,11 @@ static bool is_extcon_attached(struct extcon_dev *edev, unsigned int index)
 	return !!(edev->state & BIT(index));
 }
 
-static bool is_extcon_changed(u32 prev, u32 new, int idx, bool *attached)
+static bool is_extcon_changed(struct extcon_dev *edev, int index,
+				bool new_state)
 {
-	if (((prev >> idx) & 0x1) != ((new >> idx) & 0x1)) {
-		*attached = ((new >> idx) & 0x1) ? true : false;
-		return true;
-	}
-
-	return false;
+	int state = !!(edev->state & BIT(index));
+	return (state != new_state);
 }
 
 static bool is_extcon_property_supported(unsigned int id, unsigned int prop)
@@ -402,21 +399,13 @@ static ssize_t cable_state_show(struct device *dev,
 }
 
 /**
- * extcon_update_state() - Update the cable attach states of the extcon device
- *			   only for the masked bits.
- * @edev:	the extcon device
- * @mask:	the bit mask to designate updated bits.
- * @state:	new cable attach status for @edev
- *
- * Changing the state sends uevent with environment variable containing
- * 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.
+ * extcon_sync()	- Synchronize the states for both the attached/detached
+ * @edev:		the extcon device that has the cable.
  *
- * Note that the notifier provides which bits are changed in the state
- * variable with the val parameter (second) to the callback.
+ * This function send a notification to synchronize the all states of a
+ * specific external connector
  */
-static int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
+int extcon_sync(struct extcon_dev *edev, unsigned int id)
 {
 	char name_buf[120];
 	char state_buf[120];
@@ -425,73 +414,58 @@ static int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
 	int env_offset = 0;
 	int length;
 	int index;
+	int state;
 	unsigned long flags;
-	bool attached;
 
 	if (!edev)
 		return -EINVAL;
 
+	index = find_cable_index_by_id(edev, id);
+	if (index < 0)
+		return index;
+
 	spin_lock_irqsave(&edev->lock, flags);
 
-	if (edev->state != ((edev->state & ~mask) | (state & mask))) {
-		u32 old_state;
+	state = !!(edev->state & BIT(index));
+	raw_notifier_call_chain(&edev->nh[index], state, edev);
 
-		if (check_mutually_exclusive(edev, (edev->state & ~mask) |
-						   (state & mask))) {
-			spin_unlock_irqrestore(&edev->lock, flags);
-			return -EPERM;
-		}
+	/* This could be in interrupt handler */
+	prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
+	if (!prop_buf) {
+		/* Unlock early before uevent */
+		spin_unlock_irqrestore(&edev->lock, flags);
 
-		old_state = edev->state;
-		edev->state &= ~mask;
-		edev->state |= state & mask;
+		dev_err(&edev->dev, "out of memory in extcon_set_state\n");
+		kobject_uevent(&edev->dev.kobj, KOBJ_CHANGE);
 
-		for (index = 0; index < edev->max_supported; index++) {
-			if (is_extcon_changed(old_state, edev->state, index,
-					      &attached))
-				raw_notifier_call_chain(&edev->nh[index],
-							attached, edev);
-		}
-
-		/* This could be in interrupt handler */
-		prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
-		if (prop_buf) {
-			length = name_show(&edev->dev, NULL, prop_buf);
-			if (length > 0) {
-				if (prop_buf[length - 1] == '\n')
-					prop_buf[length - 1] = 0;
-				snprintf(name_buf, sizeof(name_buf),
-					"NAME=%s", prop_buf);
-				envp[env_offset++] = name_buf;
-			}
-			length = state_show(&edev->dev, NULL, prop_buf);
-			if (length > 0) {
-				if (prop_buf[length - 1] == '\n')
-					prop_buf[length - 1] = 0;
-				snprintf(state_buf, sizeof(state_buf),
-					"STATE=%s", prop_buf);
-				envp[env_offset++] = state_buf;
-			}
-			envp[env_offset] = NULL;
-			/* Unlock early before uevent */
-			spin_unlock_irqrestore(&edev->lock, flags);
+		return 0;
+	}
 
-			kobject_uevent_env(&edev->dev.kobj, KOBJ_CHANGE, envp);
-			free_page((unsigned long)prop_buf);
-		} else {
-			/* Unlock early before uevent */
-			spin_unlock_irqrestore(&edev->lock, flags);
+	length = name_show(&edev->dev, NULL, prop_buf);
+	if (length > 0) {
+		if (prop_buf[length - 1] == '\n')
+			prop_buf[length - 1] = 0;
+		snprintf(name_buf, sizeof(name_buf), "NAME=%s", prop_buf);
+		envp[env_offset++] = name_buf;
+	}
 
-			dev_err(&edev->dev, "out of memory in extcon_set_state\n");
-			kobject_uevent(&edev->dev.kobj, KOBJ_CHANGE);
-		}
-	} else {
-		/* No changes */
-		spin_unlock_irqrestore(&edev->lock, flags);
+	length = state_show(&edev->dev, NULL, prop_buf);
+	if (length > 0) {
+		if (prop_buf[length - 1] == '\n')
+			prop_buf[length - 1] = 0;
+		snprintf(state_buf, sizeof(state_buf), "STATE=%s", prop_buf);
+		envp[env_offset++] = state_buf;
 	}
+	envp[env_offset] = NULL;
+
+	/* Unlock early before uevent */
+	spin_unlock_irqrestore(&edev->lock, flags);
+	kobject_uevent_env(&edev->dev.kobj, KOBJ_CHANGE, envp);
+	free_page((unsigned long)prop_buf);
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(extcon_sync);
 
 /**
  * extcon_get_state() - Get the state of a external connector.
@@ -520,17 +494,22 @@ EXPORT_SYMBOL_GPL(extcon_get_state);
 
 /**
  * extcon_set_state() - Set the state of a external connector.
+ *			without a notification.
  * @edev:		the extcon device that has the cable.
  * @id:			the unique id of each external connector
  *			in extcon enumeration.
  * @state:		the new cable status. The default semantics is
  *			true: attached / false: detached.
+ *
+ * This function only set the state of a external connector without
+ * a notification. To synchronize the data of a external connector,
+ * use extcon_set_state_sync() and extcon_sync().
  */
 int extcon_set_state(struct extcon_dev *edev, unsigned int id,
 				bool cable_state)
 {
-	u32 state;
-	int index;
+	unsigned long flags;
+	int index, ret = 0;
 
 	if (!edev)
 		return -EINVAL;
@@ -539,6 +518,18 @@ int extcon_set_state(struct extcon_dev *edev, unsigned int id,
 	if (index < 0)
 		return index;
 
+	spin_lock_irqsave(&edev->lock, flags);
+
+	/* Check whether the external connector's state is changed. */
+	if (!is_extcon_changed(edev, index, cable_state))
+		goto out;
+
+	if (check_mutually_exclusive(edev,
+		(edev->state & ~BIT(index)) | (cable_state & BIT(index)))) {
+		ret = -EPERM;
+		goto out;
+	}
+
 	/*
 	 * Initialize the value of extcon property before setting
 	 * the detached state for an external connector.
@@ -546,11 +537,55 @@ int extcon_set_state(struct extcon_dev *edev, unsigned int id,
 	if (!cable_state)
 		init_property(edev, id, index);
 
-	state = cable_state ? (1 << index) : 0;
-	return extcon_update_state(edev, 1 << index, state);
+	/* Update the state for a external connector. */
+	if (cable_state)
+		edev->state |= BIT(index);
+	else
+		edev->state &= ~(BIT(index));
+out:
+	spin_unlock_irqrestore(&edev->lock, flags);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(extcon_set_state);
 
+/**
+ * extcon_set_state_sync() - Set the state of a external connector
+ *			with a notification.
+ * @edev:		the extcon device that has the cable.
+ * @id:			the unique id of each external connector
+ *			in extcon enumeration.
+ * @state:		the new cable status. The default semantics is
+ *			true: attached / false: detached.
+ *
+ * This function set the state of external connector and synchronize the data
+ * by usning a notification.
+ */
+int extcon_set_state_sync(struct extcon_dev *edev, unsigned int id,
+				bool cable_state)
+{
+	int ret, index;
+	unsigned long flags;
+
+	index = find_cable_index_by_id(edev, id);
+	if (index < 0)
+		return index;
+
+	/* Check whether the external connector's state is changed. */
+	spin_lock_irqsave(&edev->lock, flags);
+	ret = is_extcon_changed(edev, index, cable_state);
+	spin_unlock_irqrestore(&edev->lock, flags);
+	if (!ret)
+		return 0;
+
+	ret = extcon_set_state(edev, id, cable_state);
+	if (ret < 0)
+		return ret;
+
+	return extcon_sync(edev, id);
+}
+EXPORT_SYMBOL_GPL(extcon_set_state_sync);
+
 /**
  * extcon_get_property() - Get the property value of a specific cable.
  * @edev:		the extcon device that has the cable.
@@ -701,6 +736,31 @@ int extcon_set_property(struct extcon_dev *edev, unsigned int id,
 }
 EXPORT_SYMBOL_GPL(extcon_set_property);
 
+/**
+ * extcon_set_property_sync() - Set the property value of a specific cable
+			with a notification.
+ * @prop_val:		the pointer including the new value of property.
+ *
+ * When setting the property value of external connector, the external connector
+ * should be attached. The each property should be included in the list of
+ * supported properties according to the type of external connectors.
+ *
+ * Returns 0 if success or error number if fail
+ */
+int extcon_set_property_sync(struct extcon_dev *edev, unsigned int id,
+				unsigned int prop,
+				union extcon_property_value prop_val)
+{
+	int ret;
+
+	ret = extcon_set_property(edev, id, prop, prop_val);
+	if (ret < 0)
+		return ret;
+
+	return extcon_sync(edev, id);
+}
+EXPORT_SYMBOL_GPL(extcon_set_property_sync);
+
 /**
  * extcon_get_property_capability() - Get the capability of property
  *			of an external connector.

include/linux/extcon.h

@@ -222,6 +222,13 @@ extern void devm_extcon_dev_free(struct device *dev, struct extcon_dev *edev);
 extern int extcon_get_state(struct extcon_dev *edev, unsigned int id);
 extern int extcon_set_state(struct extcon_dev *edev, unsigned int id,
 				   bool cable_state);
+extern int extcon_set_state_sync(struct extcon_dev *edev, unsigned int id,
+				bool cable_state);
+
+/*
+ * Synchronize the state and property data for a specific external connector.
+ */
+extern int extcon_sync(struct extcon_dev *edev, unsigned int id);
 
 /*
  * get/set_property access the property value of each external connector.
@@ -233,6 +240,9 @@ extern int extcon_get_property(struct extcon_dev *edev, unsigned int id,
 extern int extcon_set_property(struct extcon_dev *edev, unsigned int id,
 				unsigned int prop,
 				union extcon_property_value prop_val);
+extern int extcon_set_property_sync(struct extcon_dev *edev, unsigned int id,
+				unsigned int prop,
+				union extcon_property_value prop_val);
 
 /*
  * get/set_property_capability set the capability of the property for each
@@ -317,6 +327,17 @@ static inline int extcon_set_state(struct extcon_dev *edev, unsigned int id,
 	return 0;
 }
 
+static inline int extcon_set_state_sync(struct extcon_dev *edev, unsigned int id,
+				bool cable_state)
+{
+	return 0;
+}
+
+static inline int extcon_sync(struct extcon_dev *edev, unsigned int id)
+{
+	return 0;
+}
+
 static inline int extcon_get_property(struct extcon_dev *edev, unsigned int id,
 					unsigned int prop,
 					union extcon_property_value *prop_val)
@@ -330,6 +351,13 @@ static inline int extcon_set_property(struct extcon_dev *edev, unsigned int id,
 	return 0;
 }
 
+static inline int extcon_set_property_sync(struct extcon_dev *edev,
+					unsigned int id, unsigned int prop,
+					union extcon_property_value prop_val)
+{
+	return 0;
+}
+
 static inline int extcon_get_property_capability(struct extcon_dev *edev,
 					unsigned int id, unsigned int prop)
 {
@@ -411,6 +439,6 @@ static inline int extcon_get_cable_state_(struct extcon_dev *edev, unsigned int
 static inline int extcon_set_cable_state_(struct extcon_dev *edev, unsigned int id,
 				   bool cable_state)
 {
-	return extcon_set_state(edev, id, cable_state);
+	return extcon_set_state_sync(edev, id, cable_state);
 }
 #endif /* __LINUX_EXTCON_H__ */