kernel input handler

该篇分析通用的input handler：evdev.c

源码：

　　android-5.0.2\linux-3.0.86\drivers\input\Evdev.c
功能：

　　创建/dev/input/eventx的字符设备供上层使用

源码分析：

往input子系统注册input_handler

static struct input_handler evdev_handler = {
    .event        = evdev_event,　　// 事件上报
    .connect    = evdev_connect,　　// input_device和input_handler的链接函数
    .disconnect    = evdev_disconnect,
    .fops        = &evdev_fops,　　// 字符设备的fops
    .minor        = EVDEV_MINOR_BASE,
    .name        = "evdev",
    .id_table    = evdev_ids,　　// input_device和该handler的匹配
};
static int __init evdev_init(void)
    return input_register_handler(&evdev_handler);

事件上报

　　input_device上报的数据放入到各自的buffer中

static void evdev_event(struct input_handle *handle,
            unsigned int type, unsigned int code, int value)
{
    // 封装input_device数据
    event.type = type;
    event.code = code;
    event.value = value;

    // 把event数据放入到各自的buffer中
    list_for_each_entry_rcu(client, &evdev->client_list, node)
        evdev_pass_event(client, &event);
            client->buffer[client->head++] = *event;
        client->head &= client->bufsize - 1;

    // 接收到sync事件后，唤醒
    if (type == EV_SYN && code == SYN_REPORT)
        wake_up_interruptible(&evdev->wait);
}