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/* ------------------------------------------------------------------------- */
/* */
/* 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
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 <> and
Frodo Looijaard <> */
#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;
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
* @suspend: Callback for device suspend
* @resume: Callback for device resume
* @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 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 *);
int (*suspend)(struct i2c_client *, pm_message_t mesg);
int (*resume)(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
* 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;
#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);
* struct i2c_board_info - template for device creation
* @type: chip type, to initialize
* @flags: to initialize i2c_client.flags
* @addr: stored in i2c_client.addr
* @platform_data: stored in
* @archdata: copied into
* @of_node: pointer to OpenFirmware device node
* @acpi_node: ACPI device node
* @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 acpi_dev_node acpi_node;
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.
extern int
i2c_register_board_info(int busnum, struct i2c_board_info const *info,
unsigned n);
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.
* 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 occured 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 *);
* 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_bus_recovery_info *bri);
void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
/* 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);
* 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;
#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)
struct device *parent = adapter->dev.parent;
if (parent != NULL && parent->type == &i2c_adapter_type)
return to_i2c_adapter(parent);
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 */
/* 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, \
#endif /* I2C */
/* 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);
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 */