uinput是Linux提供的一个可以在用户空间创建input设备的驱动程序。目前看到在Android 中蓝牙鼠标就是利用的 uinput 来发送key event .
kernel 中 uinput 的 init 代码如下： /drivers/input/misc/uinput.c
static int __init uinput_init(void)
{
return misc_register(&uinput_misc);
}
module_init(uinput_init);
uinput_init函数中，调用misc_register创建了一个混杂设备，所谓混杂设备本质上主设备号为10的一个字符设备，uinput_misc定义如下
static struct miscdevice uinput_misc = {
.fops = &uinput_fops,
.minor = UINPUT_MINOR,
.name = UINPUT_NAME,
};
static const struct file_operations uinput_fops = {
.owner = THIS_MODULE,
.open = uinput_open,
.release = uinput_release,
.read = uinput_read,
.write = uinput_write,
.poll = uinput_poll,
.unlocked_ioctl = uinput_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = uinput_compat_ioctl,
#endif
.llseek = no_llseek,
};
先以蓝牙鼠标的代码为实例, 来看其实现流程 ：
void bta_hh_co_open(UINT8 dev_handle, UINT8 sub_class, tBTA_HH_ATTR_MASK attr_mask,
UINT8 app_id)
{
......
// 打开 ‘ /dev/uhid ’ 节点
p_dev->fd = open(dev_path, O_RDWR | O_CLOEXEC);
//创建线程监听uinput driver 上传的事件， 其中会读取上面获取到的文件句柄
p_dev->hh_poll_thread_id = create_thread(btif_hh_poll_event_thread, p_dev);
}
void bta_hh_co_send_hid_info(btif_hh_device_t *p_dev, char *dev_name, UINT16 vendor_id,
UINT16 product_id, UINT16 version, UINT8 ctry_code,
int dscp_len, UINT8 *p_dscp)
{
struct uhid_event ev;
//创建 uinput device
ev.type = UHID_CREATE;
strncpy((char*)ev.u.create.name, dev_name, sizeof(ev.u.create.name) - 1);
ev.u.create.bus = BUS_BLUETOOTH;
ev.u.create.vendor = vendor_id;
ev.u.create.product = product_id;
...
result = uhid_write(p_dev->fd, &ev);
可以看到这里首先打开 /dev/uhid 节点， 然后写入一个 type 为 UHID_CREATE 的 uhid_event 来创建uinput 设备 。
先来看一下该节点的 open 函数:
static int uinput_open(struct inode *inode, struct file *file)
{
struct uinput_device *newdev;
newdev = kzalloc(sizeof(struct uinput_device), GFP_KERNEL);
mutex_init(&newdev->mutex);
spin_lock_init(&newdev->requests_lock);
init_waitqueue_head(&newdev->requests_waitq);
init_waitqueue_head(&newdev->waitq);
newdev->state = UIST_NEW_DEVICE;
file->private_data = newdev;
nonseekable_open(inode, file);
return 0;
}
