ilitek i2c接口touchscreen驱动

一. data structure.

1. i2c_data 数据结构， 这是代表ilitek触摸屏在kernel里的工作状况的一个数据结构。
里面的各项数据在后面都有各自的用处。

// declare i2c data member

struct i2c_data {

    // input device

        struct input_dev *input_dev;    //输入设备

        // i2c client

        struct i2c_client *client;

        // polling thread

        struct task_struct *thread;     

        // maximum x

        int max_x;

        // maximum y

        int max_y;

    // maximum touch point

    int max_tp;

    // maximum key button

    int max_btn;

        // the total number of x channel

        int x_ch;

        // the total number of y channel

        int y_ch;

        // check whether i2c driver is registered success

        int valid_i2c_register;

        // check whether input driver is registered success

        int valid_input_register;

    // check whether the i2c enter suspend or not

    int stop_polling;

    // read semaphore

    struct semaphore wr_sem;

    // protocol version

    int protocol_ver;

    // valid irq request

    int valid_irq_request;

    // work queue for interrupt use only

    struct workqueue_struct *irq_work_queue;

    // work struct for work queue

    struct work_struct irq_work;



    struct timer_list timer;



    struct completion complete;

#ifdef CONFIG_HAS_EARLYSUSPEND

    struct early_suspend early_suspend;

#endif

};

 

1. 2. dev_data.
   

   // device data
   
   struct dev_data {
   
           // device number
   
           dev_t devno;
   
           // character device
   
           struct cdev cdev;
   
           // class device
   
           struct class *class;
   
   };
   

   
   
   

1. 3.  global variables. 声明上述2数据结构的全局变量：
   

   // global variables
   
   static struct i2c_data i2c;
   
   static struct dev_data dev;
   
   static char DBG_FLAG;
   
   static char Report_Flag;
   
   
   

   
   

1. 二、设备驱动：
   
   1. init/exit
   

   /* set init and exit function for this module */
   
   module_init(ilitek_init);
   
   module_exit(ilitek_exit);
   ilitek_init:
   
   
   /*
   
   description
   
       initiali function for driver to invoke.
   
   parameters
   
   
   
       nothing
   
   return
   
       status
   
   */
   
   static int
   
   ilitek_init(
   
       void)
   
   {
   
       int ret = 0;
   
   
   
       printk(ILITEK_DEBUG_LEVEL "%s\n", __func__);
   
   
   
       // initialize global variable
   
           memset(&dev, 0, sizeof(struct dev_data));  //dev 变量 置为0
   
           memset(&i2c, 0, sizeof(struct i2c_data));  //i2c 变量 置为0
   
   
   
       // initialize mutex object
   
   #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 37)     //判断linux版本
   
       init_MUTEX(&i2c.wr_sem);             //初始化 信号量
   
   #else
   
       sema_init(&i2c.wr_sem,1);            //新版初始化信号量方式
   
   #endif
   
   
   
       i2c.wr_sem.count = 1;                //使用的信号量个数
   
   
   
       // register i2c device
   
       ret = ilitek_i2c_register_device();   //注册I2C设备
   
       if(ret < 0){
   
           printk(ILITEK_ERROR_LEVEL "%s, register i2c device, error\n", __func__);
   
           return ret;
   
       }
   
   
   
       // allocate character device driver buffer
   
       ret = alloc_chrdev_region(&dev.devno, 0, 1, ILITEK_FILE_DRIVER_NAME);  //分配字符设备驱动空间
   
           if(ret){
   
               printk(ILITEK_ERROR_LEVEL "%s, can't allocate chrdev\n", __func__);
   
           return ret;
   
       }
   
           printk(ILITEK_DEBUG_LEVEL "%s, register chrdev(%d, %d)\n", __func__, MAJOR(dev.devno), MINOR(dev.devno));
   
   
   
       // initialize character device driver
   
       cdev_init(&dev.cdev, &ilitek_fops);     //初始化字符设备驱动
   
       dev.cdev.owner = THIS_MODULE;
   
           ret = cdev_add(&dev.cdev, dev.devno, 1);   //添加字符设备
   
           if(ret < 0){
   
               printk(ILITEK_ERROR_LEVEL "%s, add character device error, ret %d\n", __func__, ret);
   
           return ret;
   
       }
   
       dev.class = class_create(THIS_MODULE, ILITEK_FILE_DRIVER_NAME);   //建立class 类。
   
       if(IS_ERR(dev.class)){
   
               printk(ILITEK_ERROR_LEVEL "%s, create class, error\n", __func__);
   
           return ret;
   
           }
   
       device_create(dev.class, NULL, dev.devno, NULL, "ilitek_ctrl");   //建立设备
   
       Report_Flag=0;
   
       return 0;
   
   }

   
   
   

1. ilitek_exit
   

   /*
   
       description
   
           driver exit function
   
       parameters
   
           none
   
       return
   
           nothing
   
       */
   
       static void
   
       ilitek_exit(
   
           void)
   
       {
   
       #ifdef CONFIG_HAS_EARLYSUSPEND //判断系统是否支持early suspend 模式
   
           unregister_early_suspend(&i2c.early_suspend); //如果支持，则注销early suspend.
   
       #endif
   
           // delete i2c driver
   
           if(i2c.client->irq != 0){
   
                   if(i2c.valid_irq_request != 0){
   
                           free_irq(i2c.client->irq, &i2c); //释放中断
   
                           printk(ILITEK_DEBUG_LEVEL "%s, free irq\n", __func__);
   
                           if(i2c.irq_work_queue){
   
                                   destroy_workqueue(i2c.irq_work_queue); //释放工作队列
   
                                   printk(ILITEK_DEBUG_LEVEL "%s, destory work queue\n", __func__);
   
                           }
   
                   }
   
           }
   
           else{
   
                   if(i2c.thread != NULL){
   
                           kthread_stop(i2c.thread); //停止i2c thread。
   
                           printk(ILITEK_DEBUG_LEVEL "%s, stop i2c thread\n", __func__);
   
                   }
   
           }
   
               if(i2c.valid_i2c_register != 0){
   
                       i2c_del_driver(&ilitek_i2c_driver); //删除i2c驱动。
   
                       printk(ILITEK_DEBUG_LEVEL "%s, delete i2c driver\n", __func__);
   
               }
   
               if(i2c.valid_input_register != 0){
   
                       input_unregister_device(i2c.input_dev); //注销设备。