TP驱动分析(下)

 

三，如何上报数据的？fts_work_func

static void fts_work_func(struct work_struct *work)

{

      DBG_FUNC(KERN_INFO"Enter %s\n", __func__);

      fts_read_data();

}

可以看到fts_work_func直接调用了fts_read_data()函数。

下面具体分析fts_read_data()函数：

/***********************************************************************

[function]:

callback: gather the finger information and calculate the X,Y

coordinate then report them to the input system;

[parameters]:

null;

[return]:

null;

***********************************************************************/

int fts_read_data(void)

{

      struct FTS_TS_DATA_T *data = i2c_get_clientdata(this_client);

      struct FTS_TS_EVENT_T *event = &data->event;

      u8 buf[32] = {0};

……

      for (k = 0; k < CFG_MAX_POINT_NUM; ++k)

      {

           buf[0] = 3 + k*6;//why should we use this function? See NOTE1

           id = 0xe;

           ret=fts_i2c_rxdata(buf, 6);//read 6 bytes data from where? See NOTE2

           if (ret > 0)

           {

                 id = buf[2]>>4;//if k=0, read data from addr 3, it means addr3 is the start of buf, so buf[2] is addr5. See NOTE3

                 touch_event = buf[0]>>6;//1st Event Flag. See NOTE4

                 if (id >= 0 && id< CFG_MAX_POINT_NUM)

                 {//computate the x,y coordination. First take out the 4 low bits from buf[0],and then put them on the high bit, at last “or” buf[1], the outcome is the value of x coodination.

                      temp = buf[0]& 0x0f;

                      temp = temp<<8;

                      temp = temp | buf[1];

          // x = temp;

                      temp1 = (buf[2])& 0x0f;

                      temp1 = temp1<<8;

                      temp1 = temp1 | buf[3];

                 // y=temp1;

                switch(orient_num){// we get orient num from items

                case 1:

                    x = temp;

                    y = temp1;

                    break;

                case 2:

……

                }

                      // buf[5] & buf[6] are not listed in the spec, so I don’t know why.

                      pressure = buf[4] & 0x3f; //it takes on sense？？

                      size = buf[5]&0xf0;

                      size = (id<<8)|size;

                      touch_event = buf[0]>>6;


                      if(touch_event == 1)

                            pressure = 0;

                      else

                            pressure = 1;



                      if (touch_event == 0) //press down

                      {

                            if(x >= 0 && x <= SCREEN_MAX_X && y >= 0 && y <= SCREEN_MAX_Y){

                                  _st_finger_infos[id].u2_pressure= pressure;

                                  _st_finger_infos[id].i2_x= (int16_t)x;

                                  _st_finger_infos[id].i2_y= (int16_t)y;

                                  _st_finger_infos[id].ui2_id = size;//size maybe indicate the touch ID.

                                  _si_touch_num ++;

                            } else {

                                  //format key1.x1.y1.key2.x2.y2.key3.x3.y3.span (x,y is topleft coordinate)

                                  for(i=0; i<key_num; i++)

                                  {

                                       if((x >= keys_data[i].x-key_span) && (x <= keys_data[i].x+key_span) && (y >= keys_data[i].y-key_span) && (y <= keys_data[i].y+key_span)) {

                                             input_report_key(data->input_dev, keys_data[i].value, 1);

                                             keys_data[i].press = 1;

                                             key_id = i;

                                             break;

                                       }

                                  }

                            }

                       } else if (touch_event == 1) { //up event

                            _st_finger_infos[id].u2_pressure= 0;

                            if(key_id !=0x80) {

                                  for(i=0;i<key_num;i++){

                                       if(keys_data[i].press == 1)

                                             input_report_key(data->input_dev, keys_data[i].value, 0);

                                  }

                                 key_id=0x80;

                            }

                      } else if (touch_event == 2) { //move event

                            _st_finger_infos[id].u2_pressure= pressure;

                            _st_finger_infos[id].i2_x= (int16_t)x;

                            _st_finger_infos[id].i2_y= (int16_t)y;

                            _st_finger_infos[id].ui2_id = size;

                            _si_touch_num ++;

                      } else /*bad event, ignore*/

                            continue;


                      if (touch_event == 1) {

                            DBG_EVENT("[TSP]id=%d up\n", id);

                      } else {//if event is down or moving, report them.

                            for(i= 0; i<CFG_MAX_POINT_NUM; ++i)

                            {

                                  if (_st_finger_infos[i].u2_pressure != 0){//report new input event

                                  input_report_abs(data->input_dev,

                                                   ABS_MT_TRACKING_ID, _st_finger_infos[i].ui2_id);

                                  input_report_abs(data->input_dev,

                                        ABS_MT_TOUCH_MAJOR, _st_finger_infos[i].u2_pressure);

                                  input_report_abs(data->input_dev,

                                        ABS_MT_POSITION_X, _st_finger_infos[i].i2_x);

                                  input_report_abs(data->input_dev,

                                                   ABS_MT_POSITION_Y, _st_finger_infos[i].i2_y);

                                  input_report_abs(data->input_dev, ABS_MT_WIDTH_MAJOR, 50);

                                  input_mt_sync(data->input_dev);

                                  }

                            }

                            input_sync(data->input_dev);

                      }


                      if (_si_touch_num == 0 ) {

                            fts_ts_release();

                      }

                      _si_touch_num = 0;

                 }

           } else {

           printk("[TSP] ERROR: in %s, line %d, ret= %d\n", __FUNCTION__,__LINE__,ret);

           }

           i_count ++;

      }//while(id != 0xf && i_count < 1);


      event->touch_point = touch_point_num;

      if (event->touch_point == 0)

           return 1;

      switch (event->touch_point) {

           case 5:

                 event->x5 = touch_info[4].i2_x;

                 event->y5 = touch_info[4].i2_y;

                 event->pressure5 = touch_info[4].u2_pressure;

           case 4:

                 event->x4 = touch_info[3].i2_x;

                 event->y4 = touch_info[3].i2_y;

                 event->pressure4 = touch_info[3].u2_pressure;

           case 3:

                 event->x3 = touch_info[2].i2_x;

                 event->y3 = touch_info[2].i2_y;

                 event->pressure3 = touch_info[2].u2_pressure;

           case 2:

                 event->x2 = touch_info[1].i2_x;

                 event->y2 = touch_info[1].i2_y;

                 event->pressure2 = touch_info[1].u2_pressure;

           case 1:

                 event->x1 = touch_info[0].i2_x;

                 event->y1 = touch_info[0].i2_y;

                 event->pressure1 = touch_info[0].u2_pressure;

                 break;

           default:

                 return -1;

      }

      return 0;

}

NOTE1: buf[0] = 3 + k*6

为什么要这样写？

先来看datasheet吧。

当K=0时，buf[0] = 3; 先从03h这里读取x,y的坐标；

当K=1时，buf[0] = 9; 从09h这里读取x,y的坐标；

……

NOTE2: ret=fts_i2c_rxdata(buf, 6);

追踪一下代码，不难发现调用过程是这样的：

fts_i2c_rxdata(u8 *rxdata, int length)

----> i2c_transfer(this_client->adapter, &msg, 1)

--------> adap->algo->master_xfer(adap, msgs, num);

//在这里其实就是imap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num);

再回到fts_i2c_rxdata(buf, 6)函数，其代码贴出如下：

static int fts_i2c_rxdata(u8 *rxdata, int length)

{

      struct i2c_msg msg;

      msg.addr = this_client->addr;

      msg.flags = 0;

      msg.len = 1;

      msg.buf = rxdata;

      ret = i2c_transfer(this_client->adapter, &msg, 1);

      msg.addr = this_client->addr;

      msg.flags = I2C_M_RD;

      msg.len = length;

      msg.buf = rxdata;

      ret = i2c_transfer(this_client->adapter, &msg, 1);

}//省略了一些语句。

上面可以看到i2c_transfer被调用了两次，也就是执行了两次的i2c读/写过程。为什么要这样呢？

第一个i2c_msg 数据结构完成写操作，写入的数值为待读出的寄存器编号；第二个i2c_msg 数据结

构完成读操作，从先前指定的寄存器中读出数据。即一次完整的读操作其实是要先进行写、再进行读的。

NOTE3: id = buf[2]>>4;

如果k=0，即从触摸IC寄存器的03h处开始读数据到buf中，那么这里的buf[2]即是05h，即：

buf[2]>>4，即可取buf的第4位到最高位的数据，即取出Touch ID，它表示第几个触摸点。（注意这里定义的buf是int 类型，故buf是32bit, 高16位在这里用不到。）

NOTE4: touch_event = buf[0]>>6;

按上面的分析可以知道，buf[0]其实是对应着03h，帮把buf[0]右移6位，即对应着第一个点的Event Flag。