1，添加USB设备信息
1.1，修改drivers/usb/serial/option.c
（1）添加PID 和 VID

#define QUECTEL_VENDOR_ID 0x2C7C 
#define QUECTEL_PRODUCT_EC20 0x0125

（2）将ID宏信息添加到option_ids数组中

static const struct usb_device_id option_ids[] = {
{ USB_DEVICE(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_EC20) }, 

（3）在option_probe中添加

if (dev_desc->idVendor == cpu_to_le16(0x05c6) &&
   dev_desc->idProduct == cpu_to_le16(0x9003) &&
   iface_desc->bInterfaceNumber >= 4)
       return -ENODEV;

if (dev_desc->idVendor == cpu_to_le16(0x05c6) &&
   dev_desc->idProduct == cpu_to_le16(0x9215) &&
   iface_desc->bInterfaceNumber >= 4)
       return -ENODEV;

if (dev_desc->idVendor == cpu_to_le16(0x2c7c) &&
   iface_desc->bInterfaceNumber >= 4)
       return -ENODEV; 

（4）在option_1port_device中

.resume          = usb_wwan_resume,
//在下面添加
.reset_resume     = usb_wwan_resume, 

1.2，修改drivers/usb/serial/usb_wwan.c
在usb_wwan_setup_urb中

if (dir == USB_DIR_OUT) {
        struct usb_device_descriptor *desc =
              &serial->dev->descriptor;
        if (desc->idVendor == cpu_to_le16(0x05c6) &&
           desc->idProduct == cpu_to_le16(0x9090))
              urb->transfer_flags |= URB_ZERO_PACKET;

        if (desc->idVendor == cpu_to_le16(0x05c6) &&
           desc->idProduct == cpu_to_le16(0x9003))
              urb->transfer_flags |= URB_ZERO_PACKET;

        if (desc->idVendor == cpu_to_le16(0x05c6) &&
           desc->idProduct == cpu_to_le16(0x9215))
              urb->transfer_flags |= URB_ZERO_PACKET;

        if (desc->idVendor == cpu_to_le16(0x2c7c))
              urb->transfer_flags |= URB_ZERO_PACKET;
 } 

2，内核配置
2.1，启用USB网络支持
-> Device Drivers
-> – Network device support
-> USB Network Adapters
-> – Multi-purpose USB Networking Framework

2.2，使能USB串口GSM、CDMA驱动
-> Device Drivers
-> [] USB support
-> <> USB Serial Converter support
-> <> USB driver for GSM and CDMA modems

2.3，使能USB的CDC ACM模式
-> Device Drivers
-> [] USB support
-> <> Support for Host-side USB
-> <> USB Modem (CDC ACM) support

2.4，使能PPP功能
-> Device Drivers
-> [] Network device support
-> <*> PPP (point-to-point protocol) support

3，添加GobiNet 驱动
3.1，将官方的驱动拷贝到内核目录drivers/net/usb下。

3.2，在drivers/net/usb目录下的Makefile里添加要编译的驱动文件。
obj-$(CONFIG_USB_GOBI_NET) += GobiNet.o
GobiNet-objs := GobiUSBNet.o QMIDevice.o QMI.o

3.3，在drivers/net/usb/Kconfig下添加Kconfig选项。

config USB_GOBI_NET
tristate"Gobi USB Net driver for Quectel module"
help
Support Quectelmodule. 5
A modemmanager with support for GobiNet is recommended. 7 Tocompile this driver as a module, choose M here: the module will be calledGobiNet.1

3.4，在内核添加官方的驱动文件，编译内核，后面使用新内核启动开发板。

-> Device Drivers 
-> [*] Network device support 
 -> -*- USB Network Adapters
-> <*> Gobi USB Net driver for Quectel module

4，交叉编译quectel-CM拨号文件
在官方提供的源码下直接make CROSS_COMPILE=arm-linux-gnueabihf-

5，将编译好的quectel-CM拷贝到开发板，执行quectel-CM -s cenet & 拨号即可，注意quectel-CM需要用到udhcpc。

6，上图：