LINUXI2C core, bus drive and device driver

I²C architecture is divided into three parts: I²c core, bus drive, device driver

I²c Core :

I²c Core provides a set of interface functions that do not depend on hardware, and the I²c-bus driver and device driver depend on the core of I²c as a link.

(1) Add/Remove I2c_adapter

int I2c_add_adapter (struct i2c_adapter *adap);

int I2c_del_adapter (struct i2c_adapter *adap);

(2) Add/Remove I2c_driver

int i2c_register_driver (struct module *owner, struct i2c_driver *drever);

int i2c_del_driver (struct i2c_driver *drever);

inline int i2c_add_driver (struct i2c_driver *drever);

(3) I2c_client attachment/Detachment

int i2c_attach_client (struct i2c_client *client);

int i2c_detach_client (struct i2c_client *client);

(4) I²c transmit, send and receive

int I2c_transfer (struct i2c_adapter *adap, struct i2c_msg *msgs, int num),/* for communication between the I²C adapter and the I²C device */

int i2c_master_send (struct i2c_client *client, const char *buf, int count);//Call I2c_transfer () function

int i2c_master_recv (struct i2c_client *client, char *buf, int count);

I²c Bus driver:

　　The I²C bus driver is the implementation of the adapter in the I²C hardware system. Contains the algorithm structure of the adapter data structure I2c_adapter and adapters primarily i2c_algorithm

I2c_adapter

1  structI2c_adapter2  {3     structModule *owner;/*Owning Module*/4UnsignedintId/*the type of algorithm, defined in I2c-id.h, starts with I2c_algo_*/5Unsignedint class;6     structI2c_algorithm *algo;/*Bus communication method struct body pointer*/7     void*algo_data;/*algorithm Data*/8     int(*client_register) (structI2c_client *);/*called when client registers*/9     int(*client_unregister) (structI2c_client *);/*called when client logs off*/Ten     structSemaphore Bus_lock;/*Spin lock to control concurrent access*/ One     structsemaphore Clist_lock; A     inttimeout; -     intretries;/*Retry Count*/ -     structDevice Dev;/*Adapter Device*/ the     structClass_device Class_dev;/*class Equipment*/ -     intnr; -     structList_head clients;/*Client Link Table header*/ -     structlist_head list; +     CharName[i2c_name_size];/*Adapter Name*/ -     structCompletion dev_released;/*for synchronization*/ +     structcompletion class_dev_released; A};

I2c_algorithm

1 structI2c_algorithm2 {3     int(*master_xfer) (structI2c_adapter *adap,structI2c_msg *msgs,intnum); 4     int(*smbus_xfer) (structI2c_adapter *adap, U16 addr, unsigned ShortFlagsCharRead_write, U8 Command,intSize, Union I2c_smbus_data *data); 5U32 (*functionality) (structI2c_adapter *); 6};

The I2C_ALGORITHM structure mainly implements the Master_xfer () function and the Functionalityh () function, where the Master_xfer () function defines the communication mode between the adapter and the device, FUNCTIONALITYH () The function is used to return algorithm supported communication protocols.

The i2c_adapter corresponds to a physical adapter, and the i2c_algorithm corresponds to a set of communication methods.

I²c Device driver:

　　The I²C device driver consists of two data structures i2c_driver and i2c_client.

I2c_driver

1 structI2c_driver2 {3     intID;4Unsignedint class;5     int(*attach_adapter) (structI2c_adapter *);/*dependent i2c_adapter function pointer*/6     int(*detach_adapter) (structI2c_adapter *);/*out of i2c_adapter function pointers*/7     int(*detach_client) (structI2c_client *);/*i²c client out of function pointer*/8     int(*probe) (structI2c_client *,Const structI2C_DEVICE_ID *);//current generic interface functions that are bound to the corresponding device9     int(*remove) (structI2c_client *);//An interface function for the current general and corresponding device to unbindTen     void(*shutdown) (structI2c_client *);//turn off the device One     int(*suspend) (structI2c_client *, pm_message_t MESG);//suspend the device, related to power management, to save power A     int(*resume) (structI2c_client *);//recovering from a suspended state -     void(*alert) (structI2c_client *, unsignedintdata); -     int(*command) (structI2c_client *client, unsignedintCmdvoid*Arg); the     structDevice_driver driver;//Drive model of I²C device -     Const structI2C_DEVICE_ID *id_table;//Matching Device list -     int(*detect) (structI2c_client *,structI2c_board_info *); -     ConstUnsigned Short*address_list; +     structlist_head clients; -};

I2c_client

1 structi2c_client2 {3Unsigned ShortFlags//I2c_client_ten indicates that the device uses a 10bit slave address, i2c_client_pec indicates that the device is using SMBus error detection4Unsigned ShortAddr//device from address, 7bit. Here is why the 7-bit, because the last thought 0 means write, 1 is read, by the 7bit address shift processing can be. Addr<<1 & 0x0 Write, addr<<1 | 0X01 is read. 5     CharName[i2c_name_size];//from the device name6     structI2c_adapter *adapter;//which adapter is attached to from the device7     structI2c_driver *driver;//the corresponding I²c drive pointer for this device8     structDevice Dev;//Device Model9     intIrq//interrupt number used by the deviceTen     structList_head detected;//for linked list operations One};

I2c_driver corresponds to a set of drive methods, i2c_client corresponds to real physical equipment, each i²c device needs a i2c_client to describe.

LINUXI2C core, bus drive and device driver