linux下USB设备驱动

static struct usb_device_id usbmouse_as_key_id_table[] = {
     {USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS, USB_INTERFACE_PROTOCOL_MOUSE)},
     {},
};

static struct urb *uk_urb;
static int usbmouse_as_key_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
     struct usb_device *dev = interface_to_usbdev(intf);/* 由接口获得设备 */
     struct usb_host_interface *interface;/*设置描述符 */
     struct usb_endpoint_descripter *endpoint;/* 端点描述符 */
     int pipe;
 
     interface = intf->cur_alterseting;/* 获得设置描述符 */
     endpoint = &interface->endpoint[0].desc;/* 获得端点描述符 */
     
     /* 分配设置input_dev */
     uk_dev = input_allocate_device();
     set_bit(EV_KEY, uk_dev->evbit);
     set_bit(EV_REP, uk_dev->evbit);
     set_bit(KEY_L, uk_dev->keybit);
     set_bit(KEY_S, uk_dev->keybit);
     set_bit(KEY_ENTER, uk_dev->keybit);
     
     input_register_device(uk_dev);
     
     /* 构造数据传输3要素 */
     /* 源 */
     pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);//生成一个中断管道,然后把得到的管道赋到了urb上
     /* 长度 */
     len = endpoint->wMaxPacketSize;
     /* 目的 */
     uk_buf = usb_buffer_alloc(0, GFP_KERNEL);
     /* 使用三要素设置URB 填充中断urb */
     usb_fill_int_urb(uk_urb, dev, pipe, usb_buf, len, usbmouse_as_key_irq, NULL, endpoint->bInterval);
     uk_urb->transer_dma = usb_buf_phys;
     uk_urb->transfer_flags |= URB_NO_TRANSFER_DMA_REP;
     usb_submit_urb(uk_urb, GFP_KERNEL);/* 将urb递交给USB核心 */
     return 0;
}
static void usbmouse_as_key_disconnect(struct usb_interface *intf)
{
     struct usb_device *dev = interface_to_usbdev(intf);

     //printk("disconnect usbmouse!\n");
     usb_kill_urb(uk_urb);
     usb_free_urb(uk_urb);

     usb_buffer_free(dev, len, usb_buf, usb_buf_phys);
     input_unregister_device(uk_dev);
     input_free_device(uk_dev);
}
static void usbmouse_as_key_irq(struct urb *urb)
{
     static unsigned char pre_val;
     /* USB鼠标数据含义
     * data[0]: bit0-左键, 1-按下, 0-松开
     *          bit1-右键, 1-按下, 0-松开
     *          bit2-中键, 1-按下, 0-松开
     *
     */
     if ((pre_val & (1<<0)) != (usb_buf[0] & (1<<0))) {
          /* 左键发生了变化 */
          input_event(uk_dev, EV_KEY, KEY_L, (usb_buf[0] & (1<<0)) ? 1 : 0);
          input_sync(uk_dev);
     }
     if ((pre_val & (1<<1)) != (usb_buf[0] & (1<<1))) {
          /* 右键发生了变化 */
          input_event(uk_dev, EV_KEY, KEY_S, (usb_buf[0] & (1<<1)) ? 1 : 0);
          input_sync(uk_dev);
     }
     if ((pre_val & (1<<2)) != (usb_buf[0] & (1<<2))) {
          /* 中键发生了变化 */
          input_event(uk_dev, EV_KEY, KEY_ENTER, (usb_buf[0] & (1<<2)) ? 1 : 0);
          input_sync(uk_dev);
     }
     pre_val = usb_buf[0];
     usb_submit_urb(uk_urb, GFP_KERNEL);/* 重新提交URB */
}