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diff --git a/include/linux/i2c.h b/include/linux/i2c.h
new file mode 100644
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+++ b/include/linux/i2c.h
@@ -0,0 +1,654 @@
+/* ------------------------------------------------------------------------- */
+/*									     */
+/* i2c.h - definitions for the i2c-bus interface			     */
+/*									     */
+/* ------------------------------------------------------------------------- */
+/*   Copyright (C) 1995-2000 Simon G. Vogl
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    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.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.							     */
+/* ------------------------------------------------------------------------- */
+
+/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
+   Frodo Looijaard <frodol@dds.nl> */
+#ifndef _LINUX_I2C_H
+#define _LINUX_I2C_H
+
+#include <linux/mod_devicetable.h>
+#include <linux/device.h>	/* for struct device */
+#include <linux/sched.h>	/* for completion */
+#include <linux/mutex.h>
+#include <linux/of.h>		/* for struct device_node */
+#include <linux/swab.h>		/* for swab16 */
+#include <uapi/linux/i2c.h>
+
+extern struct bus_type i2c_bus_type;
+extern struct device_type i2c_adapter_type;
+
+/* --- General options ------------------------------------------------	*/
+
+struct i2c_msg;
+struct i2c_algorithm;
+struct i2c_adapter;
+struct i2c_client;
+struct i2c_driver;
+union i2c_smbus_data;
+struct i2c_board_info;
+enum i2c_slave_event;
+typedef int (*i2c_slave_cb_t)(struct i2c_client *, enum i2c_slave_event, u8 *);
+
+struct module;
+
+#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
+/*
+ * The master routines are the ones normally used to transmit data to devices
+ * on a bus (or read from them). Apart from two basic transfer functions to
+ * transmit one message at a time, a more complex version can be used to
+ * transmit an arbitrary number of messages without interruption.
+ * @count must be be less than 64k since msg.len is u16.
+ */
+extern int i2c_master_send(const struct i2c_client *client, const char *buf,
+			   int count);
+extern int i2c_master_recv(const struct i2c_client *client, char *buf,
+			   int count);
+
+/* Transfer num messages.
+ */
+extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			int num);
+/* Unlocked flavor */
+extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			  int num);
+
+/* This is the very generalized SMBus access routine. You probably do not
+   want to use this, though; one of the functions below may be much easier,
+   and probably just as fast.
+   Note that we use i2c_adapter here, because you do not need a specific
+   smbus adapter to call this function. */
+extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
+			  unsigned short flags, char read_write, u8 command,
+			  int size, union i2c_smbus_data *data);
+
+/* Now follow the 'nice' access routines. These also document the calling
+   conventions of i2c_smbus_xfer. */
+
+extern s32 i2c_smbus_read_byte(const struct i2c_client *client);
+extern s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
+extern s32 i2c_smbus_read_byte_data(const struct i2c_client *client,
+				    u8 command);
+extern s32 i2c_smbus_write_byte_data(const struct i2c_client *client,
+				     u8 command, u8 value);
+extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
+				    u8 command);
+extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
+				     u8 command, u16 value);
+
+static inline s32
+i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
+{
+	s32 value = i2c_smbus_read_word_data(client, command);
+
+	return (value < 0) ? value : swab16(value);
+}
+
+static inline s32
+i2c_smbus_write_word_swapped(const struct i2c_client *client,
+			     u8 command, u16 value)
+{
+	return i2c_smbus_write_word_data(client, command, swab16(value));
+}
+
+/* Returns the number of read bytes */
+extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
+				     u8 command, u8 *values);
+extern s32 i2c_smbus_write_block_data(const struct i2c_client *client,
+				      u8 command, u8 length, const u8 *values);
+/* Returns the number of read bytes */
+extern s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client,
+					 u8 command, u8 length, u8 *values);
+extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
+					  u8 command, u8 length,
+					  const u8 *values);
+#endif /* I2C */
+
+/**
+ * struct i2c_driver - represent an I2C device driver
+ * @class: What kind of i2c device we instantiate (for detect)
+ * @attach_adapter: Callback for bus addition (deprecated)
+ * @probe: Callback for device binding
+ * @remove: Callback for device unbinding
+ * @shutdown: Callback for device shutdown
+ * @alert: Alert callback, for example for the SMBus alert protocol
+ * @command: Callback for bus-wide signaling (optional)
+ * @driver: Device driver model driver
+ * @id_table: List of I2C devices supported by this driver
+ * @detect: Callback for device detection
+ * @address_list: The I2C addresses to probe (for detect)
+ * @clients: List of detected clients we created (for i2c-core use only)
+ *
+ * The driver.owner field should be set to the module owner of this driver.
+ * The driver.name field should be set to the name of this driver.
+ *
+ * For automatic device detection, both @detect and @address_list must
+ * be defined. @class should also be set, otherwise only devices forced
+ * with module parameters will be created. The detect function must
+ * fill at least the name field of the i2c_board_info structure it is
+ * handed upon successful detection, and possibly also the flags field.
+ *
+ * If @detect is missing, the driver will still work fine for enumerated
+ * devices. Detected devices simply won't be supported. This is expected
+ * for the many I2C/SMBus devices which can't be detected reliably, and
+ * the ones which can always be enumerated in practice.
+ *
+ * The i2c_client structure which is handed to the @detect callback is
+ * not a real i2c_client. It is initialized just enough so that you can
+ * call i2c_smbus_read_byte_data and friends on it. Don't do anything
+ * else with it. In particular, calling dev_dbg and friends on it is
+ * not allowed.
+ */
+struct i2c_driver {
+	unsigned int class;
+
+	/* Notifies the driver that a new bus has appeared. You should avoid
+	 * using this, it will be removed in a near future.
+	 */
+	int (*attach_adapter)(struct i2c_adapter *) __deprecated;
+
+	/* Standard driver model interfaces */
+	int (*probe)(struct i2c_client *, const struct i2c_device_id *);
+	int (*remove)(struct i2c_client *);
+
+	/* driver model interfaces that don't relate to enumeration  */
+	void (*shutdown)(struct i2c_client *);
+
+	/* Alert callback, for example for the SMBus alert protocol.
+	 * The format and meaning of the data value depends on the protocol.
+	 * For the SMBus alert protocol, there is a single bit of data passed
+	 * as the alert response's low bit ("event flag").
+	 */
+	void (*alert)(struct i2c_client *, unsigned int data);
+
+	/* a ioctl like command that can be used to perform specific functions
+	 * with the device.
+	 */
+	int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);
+
+	struct device_driver driver;
+	const struct i2c_device_id *id_table;
+
+	/* Device detection callback for automatic device creation */
+	int (*detect)(struct i2c_client *, struct i2c_board_info *);
+	const unsigned short *address_list;
+	struct list_head clients;
+};
+#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
+
+/**
+ * struct i2c_client - represent an I2C slave device
+ * @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
+ *	I2C_CLIENT_PEC indicates it uses SMBus Packet Error Checking
+ * @addr: Address used on the I2C bus connected to the parent adapter.
+ * @name: Indicates the type of the device, usually a chip name that's
+ *	generic enough to hide second-sourcing and compatible revisions.
+ * @adapter: manages the bus segment hosting this I2C device
+ * @dev: Driver model device node for the slave.
+ * @irq: indicates the IRQ generated by this device (if any)
+ * @detected: member of an i2c_driver.clients list or i2c-core's
+ *	userspace_devices list
+ * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
+ *	calls it to pass on slave events to the slave driver.
+ *
+ * An i2c_client identifies a single device (i.e. chip) connected to an
+ * i2c bus. The behaviour exposed to Linux is defined by the driver
+ * managing the device.
+ */
+struct i2c_client {
+	unsigned short flags;		/* div., see below		*/
+	unsigned short addr;		/* chip address - NOTE: 7bit	*/
+					/* addresses are stored in the	*/
+					/* _LOWER_ 7 bits		*/
+	char name[I2C_NAME_SIZE];
+	struct i2c_adapter *adapter;	/* the adapter we sit on	*/
+	struct device dev;		/* the device structure		*/
+	int irq;			/* irq issued by device		*/
+	struct list_head detected;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	i2c_slave_cb_t slave_cb;	/* callback for slave mode	*/
+#endif
+};
+#define to_i2c_client(d) container_of(d, struct i2c_client, dev)
+
+extern struct i2c_client *i2c_verify_client(struct device *dev);
+extern struct i2c_adapter *i2c_verify_adapter(struct device *dev);
+
+static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
+{
+	struct device * const dev = container_of(kobj, struct device, kobj);
+	return to_i2c_client(dev);
+}
+
+static inline void *i2c_get_clientdata(const struct i2c_client *dev)
+{
+	return dev_get_drvdata(&dev->dev);
+}
+
+static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
+{
+	dev_set_drvdata(&dev->dev, data);
+}
+
+/* I2C slave support */
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+enum i2c_slave_event {
+	I2C_SLAVE_READ_REQUESTED,
+	I2C_SLAVE_WRITE_REQUESTED,
+	I2C_SLAVE_READ_PROCESSED,
+	I2C_SLAVE_WRITE_RECEIVED,
+	I2C_SLAVE_STOP,
+};
+
+extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
+extern int i2c_slave_unregister(struct i2c_client *client);
+
+static inline int i2c_slave_event(struct i2c_client *client,
+				  enum i2c_slave_event event, u8 *val)
+{
+	return client->slave_cb(client, event, val);
+}
+#endif
+
+/**
+ * struct i2c_board_info - template for device creation
+ * @type: chip type, to initialize i2c_client.name
+ * @flags: to initialize i2c_client.flags
+ * @addr: stored in i2c_client.addr
+ * @platform_data: stored in i2c_client.dev.platform_data
+ * @archdata: copied into i2c_client.dev.archdata
+ * @of_node: pointer to OpenFirmware device node
+ * @fwnode: device node supplied by the platform firmware
+ * @irq: stored in i2c_client.irq
+ *
+ * I2C doesn't actually support hardware probing, although controllers and
+ * devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
+ * a device at a given address.  Drivers commonly need more information than
+ * that, such as chip type, configuration, associated IRQ, and so on.
+ *
+ * i2c_board_info is used to build tables of information listing I2C devices
+ * that are present.  This information is used to grow the driver model tree.
+ * For mainboards this is done statically using i2c_register_board_info();
+ * bus numbers identify adapters that aren't yet available.  For add-on boards,
+ * i2c_new_device() does this dynamically with the adapter already known.
+ */
+struct i2c_board_info {
+	char		type[I2C_NAME_SIZE];
+	unsigned short	flags;
+	unsigned short	addr;
+	void		*platform_data;
+	struct dev_archdata	*archdata;
+	struct device_node *of_node;
+	struct fwnode_handle *fwnode;
+	int		irq;
+};
+
+/**
+ * I2C_BOARD_INFO - macro used to list an i2c device and its address
+ * @dev_type: identifies the device type
+ * @dev_addr: the device's address on the bus.
+ *
+ * This macro initializes essential fields of a struct i2c_board_info,
+ * declaring what has been provided on a particular board.  Optional
+ * fields (such as associated irq, or device-specific platform_data)
+ * are provided using conventional syntax.
+ */
+#define I2C_BOARD_INFO(dev_type, dev_addr) \
+	.type = dev_type, .addr = (dev_addr)
+
+
+#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
+/* Add-on boards should register/unregister their devices; e.g. a board
+ * with integrated I2C, a config eeprom, sensors, and a codec that's
+ * used in conjunction with the primary hardware.
+ */
+extern struct i2c_client *
+i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);
+
+/* If you don't know the exact address of an I2C device, use this variant
+ * instead, which can probe for device presence in a list of possible
+ * addresses. The "probe" callback function is optional. If it is provided,
+ * it must return 1 on successful probe, 0 otherwise. If it is not provided,
+ * a default probing method is used.
+ */
+extern struct i2c_client *
+i2c_new_probed_device(struct i2c_adapter *adap,
+		      struct i2c_board_info *info,
+		      unsigned short const *addr_list,
+		      int (*probe)(struct i2c_adapter *, unsigned short addr));
+
+/* Common custom probe functions */
+extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
+
+/* For devices that use several addresses, use i2c_new_dummy() to make
+ * client handles for the extra addresses.
+ */
+extern struct i2c_client *
+i2c_new_dummy(struct i2c_adapter *adap, u16 address);
+
+extern void i2c_unregister_device(struct i2c_client *);
+#endif /* I2C */
+
+/* Mainboard arch_initcall() code should register all its I2C devices.
+ * This is done at arch_initcall time, before declaring any i2c adapters.
+ * Modules for add-on boards must use other calls.
+ */
+#ifdef CONFIG_I2C_BOARDINFO
+extern int
+i2c_register_board_info(int busnum, struct i2c_board_info const *info,
+			unsigned n);
+#else
+static inline int
+i2c_register_board_info(int busnum, struct i2c_board_info const *info,
+			unsigned n)
+{
+	return 0;
+}
+#endif /* I2C_BOARDINFO */
+
+/**
+ * struct i2c_algorithm - represent I2C transfer method
+ * @master_xfer: Issue a set of i2c transactions to the given I2C adapter
+ *   defined by the msgs array, with num messages available to transfer via
+ *   the adapter specified by adap.
+ * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this
+ *   is not present, then the bus layer will try and convert the SMBus calls
+ *   into I2C transfers instead.
+ * @functionality: Return the flags that this algorithm/adapter pair supports
+ *   from the I2C_FUNC_* flags.
+ * @reg_slave: Register given client to I2C slave mode of this adapter
+ * @unreg_slave: Unregister given client from I2C slave mode of this adapter
+ *
+ * The following structs are for those who like to implement new bus drivers:
+ * i2c_algorithm is the interface to a class of hardware solutions which can
+ * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
+ * to name two of the most common.
+ *
+ * The return codes from the @master_xfer field should indicate the type of
+ * error code that occurred during the transfer, as documented in the kernel
+ * Documentation file Documentation/i2c/fault-codes.
+ */
+struct i2c_algorithm {
+	/* If an adapter algorithm can't do I2C-level access, set master_xfer
+	   to NULL. If an adapter algorithm can do SMBus access, set
+	   smbus_xfer. If set to NULL, the SMBus protocol is simulated
+	   using common I2C messages */
+	/* master_xfer should return the number of messages successfully
+	   processed, or a negative value on error */
+	int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
+			   int num);
+	int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
+			   unsigned short flags, char read_write,
+			   u8 command, int size, union i2c_smbus_data *data);
+
+	/* To determine what the adapter supports */
+	u32 (*functionality) (struct i2c_adapter *);
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	int (*reg_slave)(struct i2c_client *client);
+	int (*unreg_slave)(struct i2c_client *client);
+#endif
+};
+
+/**
+ * struct i2c_bus_recovery_info - I2C bus recovery information
+ * @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or
+ *	i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
+ * @get_scl: This gets current value of SCL line. Mandatory for generic SCL
+ *      recovery. Used internally for generic GPIO recovery.
+ * @set_scl: This sets/clears SCL line. Mandatory for generic SCL recovery. Used
+ *      internally for generic GPIO recovery.
+ * @get_sda: This gets current value of SDA line. Optional for generic SCL
+ *      recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
+ *      recovery.
+ * @prepare_recovery: This will be called before starting recovery. Platform may
+ *	configure padmux here for SDA/SCL line or something else they want.
+ * @unprepare_recovery: This will be called after completing recovery. Platform
+ *	may configure padmux here for SDA/SCL line or something else they want.
+ * @scl_gpio: gpio number of the SCL line. Only required for GPIO recovery.
+ * @sda_gpio: gpio number of the SDA line. Only required for GPIO recovery.
+ */
+struct i2c_bus_recovery_info {
+	int (*recover_bus)(struct i2c_adapter *);
+
+	int (*get_scl)(struct i2c_adapter *);
+	void (*set_scl)(struct i2c_adapter *, int val);
+	int (*get_sda)(struct i2c_adapter *);
+
+	void (*prepare_recovery)(struct i2c_adapter *);
+	void (*unprepare_recovery)(struct i2c_adapter *);
+
+	/* gpio recovery */
+	int scl_gpio;
+	int sda_gpio;
+};
+
+int i2c_recover_bus(struct i2c_adapter *adap);
+
+/* Generic recovery routines */
+int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
+int i2c_generic_scl_recovery(struct i2c_adapter *adap);
+
+/**
+ * struct i2c_adapter_quirks - describe flaws of an i2c adapter
+ * @flags: see I2C_AQ_* for possible flags and read below
+ * @max_num_msgs: maximum number of messages per transfer
+ * @max_write_len: maximum length of a write message
+ * @max_read_len: maximum length of a read message
+ * @max_comb_1st_msg_len: maximum length of the first msg in a combined message
+ * @max_comb_2nd_msg_len: maximum length of the second msg in a combined message
+ *
+ * Note about combined messages: Some I2C controllers can only send one message
+ * per transfer, plus something called combined message or write-then-read.
+ * This is (usually) a small write message followed by a read message and
+ * barely enough to access register based devices like EEPROMs. There is a flag
+ * to support this mode. It implies max_num_msg = 2 and does the length checks
+ * with max_comb_*_len because combined message mode usually has its own
+ * limitations. Because of HW implementations, some controllers can actually do
+ * write-then-anything or other variants. To support that, write-then-read has
+ * been broken out into smaller bits like write-first and read-second which can
+ * be combined as needed.
+ */
+
+struct i2c_adapter_quirks {
+	u64 flags;
+	int max_num_msgs;
+	u16 max_write_len;
+	u16 max_read_len;
+	u16 max_comb_1st_msg_len;
+	u16 max_comb_2nd_msg_len;
+};
+
+/* enforce max_num_msgs = 2 and use max_comb_*_len for length checks */
+#define I2C_AQ_COMB			BIT(0)
+/* first combined message must be write */
+#define I2C_AQ_COMB_WRITE_FIRST		BIT(1)
+/* second combined message must be read */
+#define I2C_AQ_COMB_READ_SECOND		BIT(2)
+/* both combined messages must have the same target address */
+#define I2C_AQ_COMB_SAME_ADDR		BIT(3)
+/* convenience macro for typical write-then read case */
+#define I2C_AQ_COMB_WRITE_THEN_READ	(I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | \
+					 I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)
+
+/*
+ * i2c_adapter is the structure used to identify a physical i2c bus along
+ * with the access algorithms necessary to access it.
+ */
+struct i2c_adapter {
+	struct module *owner;
+	unsigned int class;		  /* classes to allow probing for */
+	const struct i2c_algorithm *algo; /* the algorithm to access the bus */
+	void *algo_data;
+
+	/* data fields that are valid for all devices	*/
+	struct rt_mutex bus_lock;
+
+	int timeout;			/* in jiffies */
+	int retries;
+	struct device dev;		/* the adapter device */
+
+	int nr;
+	char name[48];
+	struct completion dev_released;
+
+	struct mutex userspace_clients_lock;
+	struct list_head userspace_clients;
+
+	struct i2c_bus_recovery_info *bus_recovery_info;
+	const struct i2c_adapter_quirks *quirks;
+};
+#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
+
+static inline void *i2c_get_adapdata(const struct i2c_adapter *dev)
+{
+	return dev_get_drvdata(&dev->dev);
+}
+
+static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
+{
+	dev_set_drvdata(&dev->dev, data);
+}
+
+static inline struct i2c_adapter *
+i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+#if IS_ENABLED(CONFIG_I2C_MUX)
+	struct device *parent = adapter->dev.parent;
+
+	if (parent != NULL && parent->type == &i2c_adapter_type)
+		return to_i2c_adapter(parent);
+	else
+#endif
+		return NULL;
+}
+
+int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));
+
+/* Adapter locking functions, exported for shared pin cases */
+void i2c_lock_adapter(struct i2c_adapter *);
+void i2c_unlock_adapter(struct i2c_adapter *);
+
+/*flags for the client struct: */
+#define I2C_CLIENT_PEC	0x04		/* Use Packet Error Checking */
+#define I2C_CLIENT_TEN	0x10		/* we have a ten bit chip address */
+					/* Must equal I2C_M_TEN below */
+#define I2C_CLIENT_WAKE	0x80		/* for board_info; true iff can wake */
+#define I2C_CLIENT_SCCB	0x9000		/* Use Omnivision SCCB protocol */
+					/* Must match I2C_M_STOP|IGNORE_NAK */
+
+/* i2c adapter classes (bitmask) */
+#define I2C_CLASS_HWMON		(1<<0)	/* lm_sensors, ... */
+#define I2C_CLASS_DDC		(1<<3)	/* DDC bus on graphics adapters */
+#define I2C_CLASS_SPD		(1<<7)	/* Memory modules */
+#define I2C_CLASS_DEPRECATED	(1<<8)	/* Warn users that adapter will stop using classes */
+
+/* Internal numbers to terminate lists */
+#define I2C_CLIENT_END		0xfffeU
+
+/* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
+#define I2C_ADDRS(addr, addrs...) \
+	((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })
+
+
+/* ----- functions exported by i2c.o */
+
+/* administration...
+ */
+#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
+extern int i2c_add_adapter(struct i2c_adapter *);
+extern void i2c_del_adapter(struct i2c_adapter *);
+extern int i2c_add_numbered_adapter(struct i2c_adapter *);
+
+extern int i2c_register_driver(struct module *, struct i2c_driver *);
+extern void i2c_del_driver(struct i2c_driver *);
+
+/* use a define to avoid include chaining to get THIS_MODULE */
+#define i2c_add_driver(driver) \
+	i2c_register_driver(THIS_MODULE, driver)
+
+extern struct i2c_client *i2c_use_client(struct i2c_client *client);
+extern void i2c_release_client(struct i2c_client *client);
+
+/* call the i2c_client->command() of all attached clients with
+ * the given arguments */
+extern void i2c_clients_command(struct i2c_adapter *adap,
+				unsigned int cmd, void *arg);
+
+extern struct i2c_adapter *i2c_get_adapter(int nr);
+extern void i2c_put_adapter(struct i2c_adapter *adap);
+
+
+/* Return the functionality mask */
+static inline u32 i2c_get_functionality(struct i2c_adapter *adap)
+{
+	return adap->algo->functionality(adap);
+}
+
+/* Return 1 if adapter supports everything we need, 0 if not. */
+static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
+{
+	return (func & i2c_get_functionality(adap)) == func;
+}
+
+/* Return the adapter number for a specific adapter */
+static inline int i2c_adapter_id(struct i2c_adapter *adap)
+{
+	return adap->nr;
+}
+
+/**
+ * module_i2c_driver() - Helper macro for registering a I2C driver
+ * @__i2c_driver: i2c_driver struct
+ *
+ * Helper macro for I2C drivers which do not do anything special in module
+ * init/exit. This eliminates a lot of boilerplate. Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_i2c_driver(__i2c_driver) \
+	module_driver(__i2c_driver, i2c_add_driver, \
+			i2c_del_driver)
+
+#endif /* I2C */
+
+#if IS_ENABLED(CONFIG_OF)
+/* must call put_device() when done with returned i2c_client device */
+extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
+
+/* must call put_device() when done with returned i2c_adapter device */
+extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
+
+#else
+
+static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
+{
+	return NULL;
+}
+
+static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
+{
+	return NULL;
+}
+#endif /* CONFIG_OF */
+
+#endif /* _LINUX_I2C_H */