IIC driver 重要结构体

借用一下其他的照片，这样方便我们分析driver;

IIC子系统可以分

i2c-dev:代表挂在bus上的设备

i2c client:代表了完整的从设备,由i2c-dev,i2c-driver组成；

i2c-adapter:代表IIC控制器,

i2c-algorithm:代表了IIC通信的规范

i2c-core:提供了IIC总线上总线驱动和设备驱动的注册、注销方法，IIC通信方法(即algorithm),与具体适配器无关的代码以及probe设备，检测设备地址的上层代码等

大概是这么理解的，下面就先粗看一下include/linux/i2c.h中列举出的重要结构体，来更进一步理解上述几个部分怎么联系起来的；

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 */     使用的通信规范方法的集合指针，代表了具体怎么干    void *algo_data;                通信方法也需要处理数据啊，这个就是告诉你干什么的    /* data fields that are valid for all devices   */    struct rt_mutex bus_lock;          锁，目前不明白用在什么地方.    int timeout;            /* in jiffies */                  超时时间？在规定的时间内没有接受到有效回应？    int retries;                                                  失败时请求重试,什么时候会失败呢?多个从设备争相发起事务是？    struct device dev;      /* the adapter device */        控制器设备    int nr;                                                               //用途不明    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;            ？                                                                                                                                                                };<pre name="code" class="html">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,              这个就是中断来临时怎么处理的，告诉哪个IIC控制器要处理什么信息               int num);    int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,                        smbus是IIC的一个子集               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_client {    unsigned short flags;       /* div., see below      */    unsigned short addr;        /* chip address - NOTE: 7bit    */                  每个IIC都有自己的地址,具体看芯片手册                    /* addresses are stored in the  */                    /* _LOWER_ 7 bits       */    char name[I2C_NAME_SIZE];                                                      IIC设备的名称,这个是和driver配对时需要用到的    struct i2c_adapter *adapter;    /* the adapter we sit on    */                 这个设备和哪个IIC控制器的bus连在一起    struct i2c_driver *driver;  /* and our access routines  */                     怎么驱动我    struct device dev;      /* the device structure     */                         我自己的一些属性    int irq;            /* irq issued by device     */                             我局有哪些中断资源呢    struct list_head detected;                                             };

struct i2c_driver {    unsigned int class;                                                        这个class是干什么呢?    /* 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 *);         初始化这个i2c设备    int (*remove)(struct i2c_client *);                                      删除这个i2c设备    /* 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;                                   这个匹配表表示匹配规则    /* 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;};