[Controlador de Android] flujo de código del controlador aw9106

代码流程：
    1.构建struct aw9106设备结构体
    2.创建struct i2c_driver aw9106_i2c_driver结构体
    3.i2c_add_driver(&aw9106_i2c_driver)注册i2c设备
    4.主要的probe函数
 
probe:
    1.创建aw9106结构体指针
    2.i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C);
    3.申请aw9106结构体空间，返回地址给结构体指针
    4.解析dtsi，获得reset(shutdown)gpio
    5.申请reset gpio, 初始化为高电平，使能引脚
    6.从reg 0x10读取芯片id， id为0x23
    7.再解析dsti，获得预设值，imax, brightness, max_brightness，rise_time, ontime, fall_time等
    8.初始化工作线程
                INIT_WORK(&aw9106->brightness_work, aw9106_brightness_work);

        通过写寄存器设置输出模式


    9.创建sys文件节点
                ret = sysfs_create_group(&aw9106->cdev.dev->kobj,&aw9106_attribute_group);
           

 static void aw9106_brightness_work(struct work_struct *work)                                                                                                                                                                
 {  
     struct aw9106 *aw9106 = container_of(work, struct aw9106,
           brightness_work);                   
    
     unsigned char i;                          
    
     if(aw9106->cdev.brightness > aw9106->cdev.max_brightness) {
         aw9106->cdev.brightness = aw9106->cdev.max_brightness;                                                                                                                                                              
     }
    
     aw9106_i2c_write(aw9106, REG_WORK_MODE_P0, 0x00);   // reg0x12，out4~5 led mode
     aw9106_i2c_write(aw9106, REG_WORK_MODE_P1, 0x00);   // reg0x13,  out0~3 led mode                                                                                                                                                        
    
     aw9106_i2c_write(aw9106, REG_EN_BREATH, 0x00);      // disable breath                                                                                                                                                   
    
     aw9106_i2c_write(aw9106, REG_CTRL, 0x03);    // reg0x11, imax (0~10ma), 256 level in 10mA                                                                                                                                                             
    
     for(i=0; i<6; i++) {                      
         aw9106_i2c_write(aw9106, REG_DIM00+i,
             aw9106->cdev.brightness);             //  set the brightness of six IO ports                                                                                                                                                     
     }
 }

i2c write:

    aw9106_i2c_write(aw9106, REG_WORK_MODE_P0, 0x00);
                |
                |
    i2c_smbus_write_byte_data(aw9106->i2c, reg_addr, reg_data);


------------------------------------------------------------------------
i2c read:
        
    aw9106_i2c_read(aw9106, REG_ID, &reg_val);
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    *data = i2c_smbus_read_byte_data(aw9106->i2c, reg_addr);