1、开发环境

开发板：AR9331 Newifi3等

源码版本：Openwrt（源码地址：https://git.lede-project.org/source.git）

源码编译宿主系统：ubuntu12.04 ubuntu14.04（vm虚拟机）

4G模块：移远EC20 EC20 EC25 AG35等

参考文档：Quectel_WCDMA&LTE_Linux_USB_Driver_User_Guide_V1.7.pdf

2、步骤

【说明】虽然大家开发板型号不一，有AR、RT、MT版本；源码也有CC、LEDE、潘多拉、老毛子的不同；但是挂载4G驱动的方法都一样。

目前EC20和EC25对路由器最兼容，现在我是Openwrt最新版本的，兼容性完美，QMI拨号非常稳定。

2.1 USB Serial驱动

当4G模块连接到USB串行驱动时，驱动程序将在目录/dev中创建设备文件，
ttyUSB0/ttyUSB1/ttyUSB2/ttyUSB3/ttyUSB4

ec20模块能用物联网卡吗_#endif

下图为各个4G模块 /ttyUSB的功能

ec20模块能用物联网卡吗_IP_02

我们的目的是需要cdc-wdm0 这个设备文件

 

ec20模块能用物联网卡吗_IP_03

接下来就是讲解如何移植USB Serial。

2.1.1 增加PID&VID

要想识别模块，客户应该在下面添加模块维和PID信息（支持EC20、EC20、EC25、AG35等4G模块）
File: [KERNEL]/drivers/usb/serial/option.c

比如AR9331的KERNEL目录在build_dir/target-mips_24kc_musl/linux-ar71xx_generic/linux-4.4.79

static const struct usb_device_id option_ids[] = {
#if 1 //Added by Quectel
{ USB_DEVICE(0x05C6, 0x9090) }, /* Quectel UC15 */
{ USB_DEVICE(0x05C6, 0x9003) }, /* Quectel UC20 */
{ USB_DEVICE(0x2C7C, 0x0125) }, /* Quectel EC25 */
{ USB_DEVICE(0x2C7C, 0x0121) }, /* Quectel EC21 */
{ USB_DEVICE(0x05C6, 0x9215) }, /* Quectel EC20 */
{ USB_DEVICE(0x2C7C, 0x0191) }, /* Quectel EG91 */
{ USB_DEVICE(0x2C7C, 0x0195) }, /* Quectel EG95 */
{ USB_DEVICE(0x2C7C, 0x0306) }, /* Quectel EG06/EP06/EM06 */
{ USB_DEVICE(0x2C7C, 0x0296) }, /* Quectel BG96 */
{ USB_DEVICE(0x2C7C, 0x0435) }, /* Quectel AG35 */
#endif

【注】只添加#if 1 到 #endif的内容，具体位置添加位置需要读者自己注意。

2.1.2 添加零包处理

根据USB协议的要求，客户需要添加处理零数据包的机制。
For Linux Kernel Version newer than 2.6.34:
File: [KERNEL]/drivers/usb/serial/usb_wwan.c

static struct urb *usb_wwan_setup_urb(struct usb_serial *serial, int endpoint,
int dir, void *ctx, char *buf, int len,void (*callback) (struct urb *))
{
……
usb_fill_bulk_urb(urb, serial->dev,
usb_sndbulkpipe(serial->dev, endpoint) | dir,
buf, len, callback, ctx);
#if 1 //Added by Quectel for zero packet
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;
}
#endif
return urb;
}

2.1.3 增加休眠后唤醒接口

当MCU进入暂停/休眠模式时，一些USB主机控制器/USB集线器将失去电源或重新设置，并且在MCU退出暂停/休眠模式后，它们不能恢复USB设备。请添加以下语句以启用重新设置恢复过程。
For Linux kernel version higher than 3.4:
File: [KERNEL]/drivers/usb/serial/option.c

static struct usb_serial_driver option_1port_device = {
……
#ifdef CONFIG_PM
.suspend = usb_wwan_suspend,
.resume = usb_wwan_resume,
#if 1 //Added by Quectel
.reset_resume = usb_wwan_resume,
#endif
#endif
};

2.1.4 使用 GobiNet or QMI WWAN

如果客户使用ucxx/ec2x/egxx/EP06/EM06/BG96/AG35，并要求GobiNet或QMI WWAN，请添加以下语句，以防止这些模块接口4被用作USB串行设备。
For Linux Kernel Version newer than 2.6.30:
File: [KERNEL]/drivers/usb/serial/option.c

static int option_probe(struct usb_serial *serial, const struct usb_device_id *id) {
struct usb_wwan_intf_private *data;
……
#if 1 //Added by Quectel
//Quectel UC20's interface 4 can be used as USB network device
if (serial->dev->descriptor.idVendor == cpu_to_le16(0x05C6) &&
serial->dev->descriptor.idProduct == cpu_to_le16(0x9003)
&& serial->interface->cur_altsetting->desc.bInterfaceNumber >= 4)
return -ENODEV;
//Quectel EC20's interface 4 can be used as USB network device
if (serial->dev->descriptor.idVendor == cpu_to_le16(0x05C6) &&
serial->dev->descriptor.idProduct == cpu_to_le16(0x9215)
&& serial->interface->cur_altsetting->desc.bInterfaceNumber >= 4)
return -ENODEV;
//Quectel EC25&EC21&EG91&EG95&EG06&EP06&EM06&BG96/AG35's interface 4 can be used as USB network device
if (serial->dev->descriptor.idVendor == cpu_to_le16(0x2C7C)
&& serial->interface->cur_altsetting->desc.bInterfaceNumber >= 4)
return -ENODEV;
#endif
/* Store device id so we can use it during attach. */
usb_set_serial_data(serial, (void *)id);
return 0;
}

2.2 QMI WWAN驱动

2.2.1 Add VID and PID

QMI WWAN driver source file is [KERNEL]/drivers/net/usb/qmi_wwan.c.
File: [KERNEL]/drivers/net/usb/qmi_wwan.c

static const struct usb_device_id products[] = {
#if 1 //Added by Quectel
#ifndef QMI_FIXED_INTF
/* map QMI/wwan function by a fixed interface number */
#define QMI_FIXED_INTF(vend, prod, num) \
.match_flags = USB_DEVICE_ID_MATCH_DEVICE |
USB_DEVICE_ID_MATCH_INT_INFO, \
.idVendor = vend, \
.idProduct = prod, \
.bInterfaceClass = 0xff, \
.bInterfaceSubClass = 0xff, \
.bInterfaceProtocol = 0xff, \
.driver_info = (unsigned long)&qmi_wwan_force_int##num,
#endif
{ QMI_FIXED_INTF(0x05C6, 0x9003, 4) }, /* Quectel UC20 */
{ QMI_FIXED_INTF(0x2C7C, 0x0125, 4) }, /* Quectel EC25 */
{ QMI_FIXED_INTF(0x2C7C, 0x0121, 4) }, /* Quectel EC21 */
{ QMI_FIXED_INTF(0x05C6, 0x9215, 4) }, /* Quectel EC20 */
{ QMI_FIXED_INTF(0x2C7C, 0x0191, 4) }, /* Quectel EG91 */
{ QMI_FIXED_INTF(0x2C7C, 0x0195, 4) }, /* Quectel EG95 */
{ QMI_FIXED_INTF(0x2C7C, 0x0306, 4) }, /* Quectel EG06/EP06/EM06 */
{ QMI_FIXED_INTF(0x2C7C, 0x0296, 4) }, /* Quectel BG96 */
{ QMI_FIXED_INTF(0x2C7C, 0x0435, 4) }, /* Quectel AG35 */
#endif

2.2.2 Add Support for Raw IP Mode

File: [KERNEL]/drivers/net/usb/qmi_wwan.c

#include <linux/usb/usbnet.h>
#include <linux/usb/cdc-wdm.h>
#if 1 //Added by Quectel
#include <linux/etherdevice.h>
struct sk_buff *qmi_wwan_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
if (dev->udev->descriptor.idVendor != cpu_to_le16(0x2C7C))
return skb;
// Skip Ethernet header from message
if (skb_pull(skb, ETH_HLEN)) {
return skb;
} else {
dev_err(&dev->intf->dev, "Packet Dropped ");
}
// Filter the packet out, release it
dev_kfree_skb_any(skb);
return NULL;
}
#include <linux/version.h>
#if (LINUX_VERSION_CODE < KERNEL_VERSION( 3,9,1 ))
static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
__be16 proto;
if (dev->udev->descriptor.idVendor != cpu_to_le16(0x2C7C))
return 1;
/* This check is no longer done by usbnet */
if (skb->len < dev->net->hard_header_len)
return 0;
switch (skb->data[0] & 0xf0) {
case 0x40:
proto = htons(ETH_P_IP);
break;
case 0x60:
proto = htons(ETH_P_IPV6);
break;
case 0x00:
if (is_multicast_ether_addr(skb->data))
return 1;
/* possibly bogus destination - rewrite just in case */
skb_reset_mac_header(skb);
goto fix_dest;
default:
/* pass along other packets without modifications */
return 1;
}
if (skb_headroom(skb) < ETH_HLEN)
return 0;
skb_push(skb, ETH_HLEN);
skb_reset_mac_header(skb);
eth_hdr(skb)->h_proto = proto;
memset(eth_hdr(skb)->h_source, 0, ETH_ALEN);
fix_dest:
memcpy(eth_hdr(skb)->h_dest, dev->net->dev_addr, ETH_ALEN);
return 1;
}
/* very simplistic detection of IPv4 or IPv6 headers */
static bool possibly_iphdr(const char *data)
{
return (data[0] & 0xd0) == 0x40;
}
#endif
#endif
……
/* if follow function exist, modify it as below */
static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf)
{
……
#if 1 //Added by Quectel
if (dev->udev->descriptor.idVendor == cpu_to_le16(0x2C7C)) {
dev_info(&intf->dev, "Quectel
EC25&EC21&EG91&EG95&EG06&EP06&EM06&BG96&AG35 work on RawIP mode\n");
dev->net->flags |= IFF_NOARP;
#if (LINUX_VERSION_CODE < KERNEL_VERSION( 3,9,1 ))
/* make MAC addr easily distinguishable from an IP header */
if (possibly_iphdr(dev->net->dev_addr)) {
dev->net->dev_addr[0] |= 0x02; /* set local assignment bit */
dev->net->dev_addr[0] &= 0xbf; /* clear "IP" bit */
}
#endif
usb_control_msg(
interface_to_usbdev(intf),
usb_sndctrlpipe(interface_to_usbdev(intf), 0),
0x22, //USB_CDC_REQ_SET_CONTROL_LINE_STATE
0x21, //USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE
1, //active CDC DTR
intf->cur_altsetting->desc.bInterfaceNumber,
NULL, 0, 100);
}
#endif
err:
return status;
}
……
/* if follow function exist, modify it as below */
static int qmi_wwan_bind_shared(struct usbnet *dev, struct usb_interface *intf)
{
……
#if 1 //Added by Quectel
if (dev->udev->descriptor.idVendor == cpu_to_le16(0x2C7C)) {
dev_info(&intf->dev, "Quectel EC25&EC21&
EG91&EG95&EG06&EP06&EM06&BG96&AG35 work on RawIP mode\n");
dev->net->flags |= IFF_NOARP;
#if (LINUX_VERSION_CODE < KERNEL_VERSION( 3,9,1 ))
/* make MAC addr easily distinguishable from an IP header */
if (possibly_iphdr(dev->net->dev_addr)) {
dev->net->dev_addr[0] |= 0x02; /* set local assignment bit */
dev->net->dev_addr[0] &= 0xbf; /* clear "IP" bit */
}
#endif
usb_control_msg(
interface_to_usbdev(intf),
usb_sndctrlpipe(interface_to_usbdev(intf), 0),
0x22, //USB_CDC_REQ_SET_CONTROL_LINE_STATE
0x21, //USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE
1, //active CDC DTR
intf->cur_altsetting->desc.bInterfaceNumber,
NULL, 0, 100);
}
#endif
err:
return status;
}
……
/* if follow struct exist, modify it as below */
static const struct driver_info qmi_wwan_info =
{
……
#if 1 //Added by Quectel
.tx_fixup = qmi_wwan_tx_fixup,
.rx_fixup = qmi_wwan_rx_fixup,
#endif
}
 
……
/* if follow struct exist, modify it as below */
static const struct driver_info qmi_wwan_force_int4 = {
……
#if 1 //Added by Quectel
.tx_fixup = qmi_wwan_tx_fixup,
.rx_fixup = qmi_wwan_rx_fixup,
#endif
};
/* if follow struct exist, modify it as below */
static const struct driver_info qmi_wwan_shared = {
……
#if 1 //Added by Quectel
.tx_fixup = qmi_wwan_tx_fixup,
.rx_fixup = qmi_wwan_rx_fixup,
#endif
};

2.3 修改配置

第一步：进入配置环境
$make menuconfig
第二步：配置

Kernel modules >>
	USB Support >>
		<*> Kmod -usb-core
		-*-Kmod -usb-net
		-*- kmod-usb-net-cdc-ether
		<*> kmod-usb-net-cdc-mbim
		-*- kmod-usb-net-cdc-ncm
		<*> kmod-usb-net-cdc-subset
		<*>kmod-usb-net-qmi-wwan
		<*>Kmod-usb-ohci     //这个选项一定要勾选，否则可能无法在系统中查看设备
		<*>Kmod-usb-serial
		<*>Kmod-usb-serial-option
		<*>Kmod-usb-serial-wwan
		<*>kmod-usb-uhci
		<*>Kmod-usb2
NetWork   >>
	<*> wwan
	<*>chat
	<*>ppp
	<*>uqmi
Utilities
	-*- comgt
	<*> comgt-ncm 
	<*>usb-modeswitch
Luci
1. Collections
  		<*> luci
3. Applications
  		<*> luci-app-multiwan (optional to support multiple 3g dongles)
  		<*> luci-app-qos (optional to provide QOS support)
6. Protocols
  		<*> luci-proto-3g
  		-*- luci-proto-ppp

2.4 编译测试

以上操作完成后就是编译源码了。

$ make V=s

将编译好固件烧写进入板子中，插入4G模块，在dev目录下查看，就会出现cdc-wdm0 这个设备文件

ec20模块能用物联网卡吗_IP_03

有以上信息表示驱动配置成功，接下来就拨号了。

3.5 拨号上网

3.5.1 安装交叉编译工具

进入源码目录，执行mkae menuconfig

cd lede_source
make menuconfig

 选中Toolchain

 

ec20模块能用物联网卡吗_ec20模块能用物联网卡吗_05

保存，编译

make V=99

找到交叉工具链的位置：

ec20模块能用物联网卡吗_ec20模块能用物联网卡吗_06

 这里我们演示将交叉工具链安装到 ubuntu 的“/opt”目录下。 首先切换到 openwrt 源码的根目录下，输入如下命令：

cd ~/lede_source/bin/targets/ramips/mt7621
sudo tar xjvf openwrt-toolchain-ramips-mt7621_gcc-7.4.0_musl.Linux-x86_64.tar.bz2 -C /opt

 最后，设置环境变量

sudo vi /etc/bash.bashrc

 在最后一行添加
 

export PATH=/opt/openwrt-toolchain-ramips-mt7621_gcc-7.4.0_musl.Linux-x86_64/toolchain-mipsel_24kc_gcc-7.4.0_musl/bin:$PATH
export STAGING_DIR=/your_openwrt_path/staging_dir

 《注意》上面这个“STAGING_DIR”变量中的“your_openwrt_path”是读者实际放 openwrt源码的根目录，如果“STAGING_DIR”变量不设置的话，会在用交叉工具链编译文件时有警告，但是不影响编译结果。最后保存退出。接着在终端执行以下命令：

source /etc/bash.bashrc

测试是否安装成功： 

mipsel-openwrt-linux-gcc -v

 3.5.2 编译拨号应用程序

拨号程序仍然使用移远提供的quectel-CM（下载地址在文章末尾），这是一个4G连接管理程序，这里没什么说的，执行：

$mipsel-openwrt-linux-musl-gcc *.c -o quectel-CM -lpthread –ldl

【注】也可将quectel-CM下的Makefile文件修改成如下，然后 make

CROSS-COMPILE:= mips-openwrt-linux-   #AR9331开发板的交叉编译工具（其他的自行修改）
CC:=$(CROSS-COMPILE)gcc
LD:=$(CROSS-COMPILE)ld
release: clean
	$(CC) -Wall -s QmiWwanCM.c GobiNetCM.c main.c MPQMUX.c QMIThread.c util.c udhcpc.c -o quectel-CM -lpthread -ldl
debug: clean
	$(CC) -Wall -g QmiWwanCM.c GobiNetCM.c main.c MPQMUX.c QMIThread.c util.c udhcpc.c -o quectel-CM -lpthread -ldl
clean:
	rm -rf quectel-CM *~

【注】移远提供的拨号程序下载地址在文章末尾（包含参考文档）。

交叉编译后得到可执行文件：“quectel-CM” ，然后将quectel-CM可执行文件用wincp软件拷贝到AR9331开发板中，执行：

chmod 777 quectel-CM   #先改变权限
./quectel-CM &

出现如下效果，说明拨号成功：

ec20模块能用物联网卡吗_#if_07

 接下来ping一下百度首页地址，看是否可以联网。

ec20模块能用物联网卡吗_ec20模块能用物联网卡吗_08

说明测试成功，开发板可以上网了。

3.6 后续问题

问题1：能ping通百度IP地址，无法ping通其域名www.baidu.com

这里需要添加DNS解析服务器的地址，在/etc目录配置resolv.conf文件添加DNS客户，它包含了主机的域名搜索顺序和DNS服务器的地址。开发板执行：

vim /etc/resolv.conf

编辑内容：

nameserver 114.114.114.114  #国内的DNS
nameserver 8.8.8.8          #国外的DNS

接下来，ping www.baidu.com

ec20模块能用物联网卡吗_#if_09

 问题2：路由器能上网后，其他设备连接此路由器不能上网

ifconfig -a 看是否有wwan0这个端口

ec20模块能用物联网卡吗_4G路由器_10

然后修改配置文件

vim /etc/config/network

添加如下内容:

config interface 'wan'
        option  device '/dev/cdc-wdm0'
        option proto 'qmi'
        option apn  'cnnet'
        option username 'card'
        option password 'card'
        option ifname 'wwan0'

ec20模块能用物联网卡吗_IP_11

登录到路由器web界面，点击网路下的接口，也就是network下的interface，会发现有这么一个设备，点击连接

ec20模块能用物联网卡吗_#endif_12


到此为止，4G路由器就搞定了。