2.6内核 输入子系统分析 二

##########################
void input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value)
{
struct input_handle *handle;
........................................................................................................
switch (type) {
case EV_ABS:

if (code > ABS_MAX || !test_bit(code, dev->absbit))//一些条件测试
return;

if (dev->absfuzz[code]) {
if ((value > dev->abs[code] - (dev->absfuzz[code] >> 1)) &&
(value < dev->abs[code] + (dev->absfuzz[code] >> 1)))
return;

if ((value > dev->abs[code] - dev->absfuzz[code]) &&
(value < dev->abs[code] + dev->absfuzz[code]))
value = (dev->abs[code] * 3 + value) >> 2;

if ((value > dev->abs[code] - (dev->absfuzz[code] << 1)) &&
(value < dev->abs[code] + (dev->absfuzz[code] << 1)))
value = (dev->abs[code] + value) >> 1;
}

if (dev->abs[code] == value)//比较当前值与上一次都值是否相同，相同则不作处理
return;

dev->abs[code] = value;//备份当前值，以便下一次作比较
break;
...............................................................................................................
if (type != EV_SYN)
dev->sync = 0;

if (dev->grab)
dev->grab->handler->event(dev->grab, type, code, value);
else
list_for_each_entry(handle, &dev->h_list, d_node)//通过input_dev找出与其联系的input_handle
if (handle->open)//相应的接口设备(比如tsdev)被打开(通过调用tsdev.c的tsdev_open函数进而调用input_open_device
函数增加handle->open的计数值)
handle->handler->event(handle, type, code, value);//调用该接口设备的event函数对数据进行处理
}

################
在结束
################
static void tsdev_event(struct input_handle *handle, unsigned int type,
unsigned int code, int value)
{
struct tsdev *tsdev = handle->private;
struct tsdev_list *list;
struct timeval time;

switch (type) {
case EV_ABS:
switch (code) {
case ABS_X:
tsdev->x = value;//记录x坐标值
break;
case ABS_Y:
tsdev->y = value;//记录y坐标值
break;
case ABS_PRESSURE:
if (value > handle->dev->absmax[ABS_PRESSURE])
value = handle->dev->absmax[ABS_PRESSURE];
value -= handle->dev->absmin[ABS_PRESSURE];
if (value < 0)
value = 0;
tsdev->pressure = value;//记录触摸屏的按压状态
break;
}
break;
...................................................................................................
if (type != EV_SYN || code != SYN_REPORT)//键值的传递以EV_SYN为结束标志(通过input_sync函数)，等到数据都填充好tsdev结构后再统一发送出去，否则直接返回，继续填充另一个数据
return;

list_for_each_entry(list, &tsdev->list, node) { //通过tsdev获取struct tsdev_list结构(在tsdev_open函数中定义):
//list_add_tail(&list->node, &tsdev_table[i]->list);
int x, y, tmp;

do_gettimeofday(&time); //填充事件的时间
list->event[list->head].millisecs = time.tv_usec / 100;
list->event[list->head].pressure = tsdev->pressure;//填充触摸屏的状态

x = tsdev->x;
y = tsdev->y;


if (!list->raw) {
x = ((x * tsdev->cal.xscale) >> 8) + tsdev->cal.xtrans;
y = ((y * tsdev->cal.yscale) >> 8) + tsdev->cal.ytrans;
if (tsdev->cal.xyswap) {
tmp = x; x = y; y = tmp;
}
}

list->event[list->head].x = x; //填充x坐标值
list->event[list->head].y = y; //填充y坐标值
list->head = (list->head + 1) & (TSDEV_BUFFER_SIZE - 1);//更新写指针
kill_fasync(&list->fasync, SIGIO, POLL_IN);
}
wake_up_interruptible(&tsdev->wait);//唤醒睡眠在tsdev->wait下等待数据都进程读取数据。至此，数据传递过程结束，开始新一轮的数据传递。
}