i2c的数据结构

1、i2c_adapter

struct i2c_adapter{struct module *owner;unsigned int id;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*/u8 level; /* nesting level for lockdep */struct mutex bus_lock;int timeout;/* in jiffies */int retries;struct device dev;/* the adapter device */int nr;char name[48];struct completion dev_released;};

    i2c_adapter is the structure used to identify a physical i2c bus along with the access algorithms necessary to access it.

2、i2c_algorithm

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 *);};

/*
 * 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.
 */
3、i2c_client

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 i2c_driver *driver;/* and our access routines*/struct device dev;/* the device structure*/int irq;/* irq issued by device*/struct list_head detected;};

/**
 * 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
 * @driver: device's driver, hence pointer to access routines
 * @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.
 */
4、i2c_driver

struct i2c_driver{int id;unsigned int class;/* Notifies the driver that a new bus has appeared or is about to be * removed. You should avoid using this if you can, it will probably * be removed in a near future. */int (*attach_adapter)(struct i2c_adapter *);int (*detach_adapter)(struct i2c_adapter *);/* 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 *);/* 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 *, int kind, struct i2c_board_info *);const struct i2c_client_address_data *address_data;struct list_head clients;};

/**
 * struct i2c_driver - represent an I2C device driver
 * @id: Unique driver ID (optional)
 * @class: What kind of i2c device we instantiate (for detect)
 * @attach_adapter: Callback for bus addition (for legacy drivers)
 * @detach_adapter: Callback for bus removal (for legacy drivers)
 * @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
 * @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_data: The I2C addresses to probe, ignore or force (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_data 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.
 */
5、i2c_msg

struct i2c_msg {__u16 addr;/* slave address*/__u16 flags;#define I2C_M_TEN0x0010/* this is a ten bit chip address */#define I2C_M_RD0x0001/* read data, from slave to master */#define I2C_M_NOSTART0x4000/* if I2C_FUNC_PROTOCOL_MANGLING */#define I2C_M_REV_DIR_ADDR0x2000/* if I2C_FUNC_PROTOCOL_MANGLING */#define I2C_M_IGNORE_NAK0x1000/* if I2C_FUNC_PROTOCOL_MANGLING */#define I2C_M_NO_RD_ACK0x0800/* if I2C_FUNC_PROTOCOL_MANGLING */#define I2C_M_RECV_LEN0x0400/* length will be first received byte */__u16 len;/* msg length*/__u8 *buf;/* pointer to msg data*/};

/**
 * struct i2c_msg - an I2C transaction segment beginning with START
 * @addr: Slave address, either seven or ten bits.  When this is a ten
 * bit address, I2C_M_TEN must be set in @flags and the adapter
 * must support I2C_FUNC_10BIT_ADDR.
 * @flags: I2C_M_RD is handled by all adapters.  No other flags may be
 * provided unless the adapter exported the relevant I2C_FUNC_*
 * flags through i2c_check_functionality().
 * @len: Number of data bytes in @buf being read from or written to the
 * I2C slave address.  For read transactions where I2C_M_RECV_LEN
 * is set, the caller guarantees that this buffer can hold up to
 * 32 bytes in addition to the initial length byte sent by the
 * slave (plus, if used, the SMBus PEC); and this value will be
 * incremented by the number of block data bytes received.
 * @buf: The buffer into which data is read, or from which it's written.
 *
 * An i2c_msg is the low level representation of one segment of an I2C
 * transaction.  It is visible to drivers in the @i2c_transfer() procedure,
 * to userspace from i2c-dev, and to I2C adapter drivers through the
 * @i2c_adapter.@master_xfer() method.
 *
 * Except when I2C "protocol mangling" is used, all I2C adapters implement
 * the standard rules for I2C transactions.  Each transaction begins with a
 * START.  That is followed by the slave address, and a bit encoding read
 * versus write.  Then follow all the data bytes, possibly including a byte
 * with SMBus PEC.  The transfer terminates with a NAK, or when all those
 * bytes have been transferred and ACKed.  If this is the last message in a
 * group, it is followed by a STOP.  Otherwise it is followed by the next
 * @i2c_msg transaction segment, beginning with a (repeated) START.
 *
 * Alternatively, when the adapter supports I2C_FUNC_PROTOCOL_MANGLING then
 * passing certain @flags may have changed those standard protocol behaviors.
 * Those flags are only for use with broken/nonconforming slaves, and with
 * adapters which are known to support the specific mangling options they
 * need (one or more of IGNORE_NAK, NO_RD_ACK, NOSTART, and REV_DIR_ADDR).
 */