for (minor = 0; minor < EVDEV_MINORS && evdev_table[minor]; minor++);
if (minor == EVDEV_MINORS) {
printk(KERN_ERR "evdev: no more free evdev devices\n");
return -ENFILE;
}

evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);//为每个匹配evdev_handler的设备创建一个evdev。
if (!evdev)
return -ENOMEM;

INIT_LIST_HEAD(&evdev->client_list);
init_waitqueue_head(&evdev->wait);

evdev->exist = 1;
evdev->minor = minor;
evdev->handle.dev = dev;
evdev->handle.name = evdev->name;
evdev->handle.handler = handler;
evdev->handle.private = evdev;
sprintf(evdev->name, "event%d", minor);

evdev_table[minor] = evdev;//记录evdev的位置，字符设备/dev/input/evnetx访问时根据次设备号及EVDEV_MINOR_BASE最终在evdev_open中找到对应的evdev
devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor),
cdev = class_device_create(&input_class, &dev->cdev, devt,dev->cdev.dev, evdev->name);//创建了event字符设备节点
……
}

4、input字符设备的打开过程

static int input_open_file(struct inode *inode, struct file *file)
{
struct input_handler *handler = input_table[iminor(inode) >> 5];
//得到对应的input_handler
const struct file_operations *old_fops, *new_fops = NULL;
int err;
if (!handler || !(new_fops = fops_get(handler->fops)))
//取出对应input_handler的file_operations
return -ENODEV;
if (!new_fops->open) {
fops_put(new_fops);
return -ENODEV;
}
old_fops = file->f_op;
file->f_op = new_fops;//重定位打开的设备文件的操作方法
err = new_fops->open(inode, file);
if (err) {
fops_put(file->f_op);
file->f_op = fops_get(old_fops);
}
fops_put(old_fops);
return err;
}

5、input字符设备的其它操作

由于在open阶段已经把设备文件的操作操作方法重定位了到了具体的input_handler，所以其它接口操作（read、write、ioctl等），由各个input_handler的fops方法决定。如evdev.c中的：evdev_fops。