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diff --git a/include/linux/extcon.h b/include/linux/extcon.h
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+/*
+ * External connector (extcon) class driver
+ *
+ * Copyright (C) 2012 Samsung Electronics
+ * Author: Donggeun Kim <dg77.kim@samsung.com>
+ * Author: MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * based on switch class driver
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+*/
+
+#ifndef __LINUX_EXTCON_H__
+#define __LINUX_EXTCON_H__
+
+#include <linux/notifier.h>
+
+#define SUPPORTED_CABLE_MAX 32
+#define CABLE_NAME_MAX 30
+
+/*
+ * The standard cable name is to help support general notifier
+ * and notifee device drivers to share the common names.
+ * Please use standard cable names unless your notifier device has
+ * a very unique and abnormal cable or
+ * the cable type is supposed to be used with only one unique
+ * pair of notifier/notifee devices.
+ *
+ * Please add any other "standard" cables used with extcon dev.
+ *
+ * You may add a dot and number to specify version or specification
+ * of the specific cable if it is required. (e.g., "Fast-charger.18"
+ * and "Fast-charger.10" for 1.8A and 1.0A chargers)
+ * However, the notifee and notifier should be able to handle such
+ * string and if the notifee can negotiate the protocol or idenify,
+ * you don't need such convention. This convention is helpful when
+ * notifier can distinguish but notifiee cannot.
+ */
+enum extcon_cable_name {
+ EXTCON_USB = 0,
+ EXTCON_USB_HOST,
+ EXTCON_TA, /* Travel Adaptor */
+ EXTCON_FAST_CHARGER,
+ EXTCON_SLOW_CHARGER,
+ EXTCON_CHARGE_DOWNSTREAM, /* Charging an external device */
+ EXTCON_HDMI,
+ EXTCON_MHL,
+ EXTCON_DVI,
+ EXTCON_VGA,
+ EXTCON_DOCK,
+ EXTCON_LINE_IN,
+ EXTCON_LINE_OUT,
+ EXTCON_MIC_IN,
+ EXTCON_HEADPHONE_OUT,
+ EXTCON_SPDIF_IN,
+ EXTCON_SPDIF_OUT,
+ EXTCON_VIDEO_IN,
+ EXTCON_VIDEO_OUT,
+ EXTCON_MECHANICAL,
+};
+extern const char *extcon_cable_name[];
+
+struct extcon_cable;
+
+/**
+ * struct extcon_dev - An extcon device represents one external connector.
+ * @name The name of this extcon device. Parent device name is used
+ * if NULL.
+ * @supported_cable Array of supported cable name ending with NULL.
+ * If supported_cable is NULL, cable name related APIs
+ * are disabled.
+ * @mutually_exclusive Array of mutually exclusive set of cables that cannot
+ * be attached simultaneously. The array should be
+ * ending with NULL or be NULL (no mutually exclusive
+ * cables). For example, if it is { 0x7, 0x30, 0}, then,
+ * {0, 1}, {0, 1, 2}, {0, 2}, {1, 2}, or {4, 5} cannot
+ * be attached simulataneously. {0x7, 0} is equivalent to
+ * {0x3, 0x6, 0x5, 0}. If it is {0xFFFFFFFF, 0}, there
+ * can be no simultaneous connections.
+ * @print_name An optional callback to override the method to print the
+ * name of the extcon device.
+ * @print_state An optional callback to override the method to print the
+ * status of the extcon device.
+ * @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.
+ * @lock
+ * @max_supported Internal value to store the number of cables.
+ * @extcon_dev_type Device_type struct to provide attribute_groups
+ * customized for each extcon device.
+ * @cables Sysfs subdirectories. Each represents one cable.
+ *
+ * In most cases, users only need to provide "User initializing data" of
+ * this struct when registering an extcon. In some exceptional cases,
+ * optional callbacks may be needed. However, the values in "internal data"
+ * are overwritten by register function.
+ */
+struct extcon_dev {
+ /* --- Optional user initializing data --- */
+ const char *name;
+ const char **supported_cable;
+ const u32 *mutually_exclusive;
+
+ /* --- Optional callbacks to override class functions --- */
+ ssize_t (*print_name)(struct extcon_dev *edev, char *buf);
+ ssize_t (*print_state)(struct extcon_dev *edev, char *buf);
+
+ /* --- Internal data. Please do not set. --- */
+ struct device *dev;
+ u32 state;
+ struct raw_notifier_head nh;
+ struct list_head entry;
+ spinlock_t lock; /* could be called by irq handler */
+ int max_supported;
+
+ /* /sys/class/extcon/.../cable.n/... */
+ struct device_type extcon_dev_type;
+ struct extcon_cable *cables;
+ /* /sys/class/extcon/.../mutually_exclusive/... */
+ struct attribute_group attr_g_muex;
+ struct attribute **attrs_muex;
+ struct device_attribute *d_attrs_muex;
+};
+
+/**
+ * struct extcon_cable - An internal data for each cable of extcon device.
+ * @edev The extcon device
+ * @cable_index Index of this cable in the edev
+ * @attr_g Attribute group for the cable
+ * @attr_name "name" sysfs entry
+ * @attr_state "state" sysfs entry
+ * @attrs Array pointing to attr_name and attr_state for attr_g
+ */
+struct extcon_cable {
+ struct extcon_dev *edev;
+ int cable_index;
+
+ struct attribute_group attr_g;
+ struct device_attribute attr_name;
+ struct device_attribute attr_state;
+
+ struct attribute *attrs[3]; /* to be fed to attr_g.attrs */
+};
+
+/**
+ * struct extcon_specific_cable_nb - An internal data for
+ * extcon_register_interest().
+ * @internal_nb a notifier block bridging extcon notifier and cable notifier.
+ * @user_nb user provided notifier block for events from a specific cable.
+ * @cable_index the target cable.
+ * @edev the target extcon device.
+ * @previous_value the saved previous event value.
+ */
+struct extcon_specific_cable_nb {
+ struct notifier_block internal_nb;
+ struct notifier_block *user_nb;
+ int cable_index;
+ struct extcon_dev *edev;
+ unsigned long previous_value;
+};
+
+#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);
+
+/*
+ * get/set/update_state access the 32b encoded state value, which represents
+ * states of all possible cables of the multistate port. For example, if one
+ * calls extcon_set_state(edev, 0x7), it may mean that all the three cables
+ * are attached to the port.
+ */
+static inline u32 extcon_get_state(struct extcon_dev *edev)
+{
+ return edev->state;
+}
+
+extern int extcon_set_state(struct extcon_dev *edev, u32 state);
+extern int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state);
+
+/*
+ * get/set_cable_state access each bit of the 32b encoded state value.
+ * They are used to access the status of each cable based on the cable_name
+ * or cable_index, which is retrived by extcon_find_cable_index
+ */
+extern int extcon_find_cable_index(struct extcon_dev *sdev,
+ const char *cable_name);
+extern int extcon_get_cable_state_(struct extcon_dev *edev, int cable_index);
+extern int extcon_set_cable_state_(struct extcon_dev *edev, int cable_index,
+ bool cable_state);
+
+extern int extcon_get_cable_state(struct extcon_dev *edev,
+ const char *cable_name);
+extern int extcon_set_cable_state(struct extcon_dev *edev,
+ const char *cable_name, bool cable_state);
+
+/*
+ * Following APIs are for notifiees (those who want to be notified)
+ * to register a callback for events from a specific cable of the extcon.
+ * Notifiees are the connected device drivers wanting to get notified by
+ * a specific external port of a connection device.
+ */
+extern int extcon_register_interest(struct extcon_specific_cable_nb *obj,
+ const char *extcon_name,
+ const char *cable_name,
+ struct notifier_block *nb);
+extern int extcon_unregister_interest(struct extcon_specific_cable_nb *nb);
+
+/*
+ * Following APIs are to monitor every action of a notifier.
+ * Registerer gets notified for every external port of a connection device.
+ * Probably this could be used to debug an action of notifier; however,
+ * we do not recommend to use this at normal 'notifiee' device drivers who
+ * want to be notified by a specific external port of the notifier.
+ */
+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)
+{
+ return 0;
+}
+
+static inline void extcon_dev_unregister(struct extcon_dev *edev) { }
+
+static inline u32 extcon_get_state(struct extcon_dev *edev)
+{
+ return 0;
+}
+
+static inline int extcon_set_state(struct extcon_dev *edev, u32 state)
+{
+ return 0;
+}
+
+static inline int extcon_update_state(struct extcon_dev *edev, u32 mask,
+ u32 state)
+{
+ return 0;
+}
+
+static inline int extcon_find_cable_index(struct extcon_dev *edev,
+ const char *cable_name)
+{
+ return 0;
+}
+
+static inline int extcon_get_cable_state_(struct extcon_dev *edev,
+ int cable_index)
+{
+ return 0;
+}
+
+static inline int extcon_set_cable_state_(struct extcon_dev *edev,
+ int cable_index, bool cable_state)
+{
+ return 0;
+}
+
+static inline int extcon_get_cable_state(struct extcon_dev *edev,
+ const char *cable_name)
+{
+ return 0;
+}
+
+static inline int extcon_set_cable_state(struct extcon_dev *edev,
+ const char *cable_name, int state)
+{
+ return 0;
+}
+
+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;
+}
+
+static inline int extcon_register_interest(struct extcon_specific_cable_nb *obj,
+ const char *extcon_name,
+ const char *cable_name,
+ struct notifier_block *nb)
+{
+ return 0;
+}
+
+static inline int extcon_unregister_interest(struct extcon_specific_cable_nb
+ *obj)
+{
+ return 0;
+}
+#endif /* CONFIG_EXTCON */
+#endif /* __LINUX_EXTCON_H__ */