在ARM平台上实现4G模块的PPP拨号上网，参考网上的资料和自己的理解，从一无所知到开发完成花了一周多。最后看到ARM板ping通www.baidu.com时甚是高兴，现将此过程整理如下。当然，除此之外要做的工作还有很多。

4G模块使用的SIMTECH 的SIM7100C，SIM7100C带有UART和USB接口，在考虑速度上我们使用USB接口和ARM进行通信。所以向Linux内核添加3G模块的驱动(USB转串口驱动)和PPP协议的支持，然后编译内核并下载到开发板。

1. 编译内核

◇ 大容量存储驱动

> Device Drivers > USB support

make ARCH=arm menuconfig配置USB驱动：

USB Mass Storage support

[*]       USB Mass Storage verbose debug

Realtek Card Reader support

[*]         Realtek Card Reader autosuspend support

Datafab Compact Flash Reader support

◇ USB驱动

> Device Drivers > USB support

Inventra Highspeed Dual Role Controller (TI, ADI, ...)

MUSB Mode Selection (Dual Role mode)  --->

Platform Glue Layer (TI DSPS platforms)  --->

MUSB DMA mode (Disable DMA (always use PIO))  --->

USB Serial Converter support  --->

[*]      USBGeneric Serial Driver

USBdriver for GSM and CDMA modems

◇ PPP驱动

> Device Drivers > Network device support

PPP (point-to-point protocol) support

PPP BSD-Compress compression

PPP Deflate compression

[*]     PPP filtering

PPP MPPE compression (encryption)

[*]     PPP multilink support

PPP over Ethernet

PPP support for async serial ports

PPP support for sync tty ports

SLIP (serial line) support

[*]   CSLIP compressed headers

2. 交叉编译libusb

下载usblib库和libusb-compat

https://sourceforge.NET/projects/libusb/files/

[email protected]:/opt/usb-tools/libusb-1.0.20# mkdir install

configure: error: "udev support requested but libudev not installed"(解决：添加--disable-udev)

[email protected]:/opt/usb-tools/libusb-1.0.20# ./configure --host=arm-none-linux-gnueabi --prefix=/opt/usb-tools/libusb-1.0.20/install --disable-udev

[email protected]:/opt/usb-tools/libusb-1.0.20# make

[email protected]:/opt/usb-tools/libusb-1.0.20# make install

添加环境变量 http://www.linuxidc.com/Linux/2011-03/33432.htm(PKG_CONFIG_PATH设置)

[email protected]:/opt/usb-tools/libusb-1.0.20# export PKG_CONFIG_PATH=/opt/usb-tools/libusb-1.0.20/install/lib/pkgconfig:$PKG_CONFIG_PATH

[email protected]:/opt/usb-tools/libusb-1.0.20# echo $PKG_CONFIG_PATH

编译libusb-compat：

[email protected]:/opt/usb-tools/libusb-compat-0.1.5# ./configure --host=arm-none-linux-gnueabi --prefix=/opt/usb-tools/libusb-compat-0.1.5/install

[email protected]:/opt/usb-tools/libusb-compat-0.1.5# make

[email protected]:/opt/usb-tools/libusb-compat-0.1.5# make install

将生成的libusb-1.0.20和libusb-compat-0.1.5下的库文件复制到ARM板上的linux的/lib下面即可。

3. 交叉编译4G模块驱动

交叉编译GobiSerial.c(ARCH=arm CC=arm-none-linux-gnueabi-gcc)，得到GobiSerial.ko。复制到ARM板安装驱动

#insmod GobiSerial.ko

4. 查看驱动运行状况

插上4G模块，虚拟出6个ttyUSB，它们分别是：

[email protected]:/# ls /dev/ttyUSB*

/dev/ttyUSB0  /dev/ttyUSB1  /dev/ttyUSB2  /dev/ttyUSB3  /dev/ttyUSB4  /dev/ttyUSB5

1) /dev/ttyUSB0-diag port for output developing messages

2) /dev/ttyUSB1- NMEA port for GPS NMEA data output

3) /dev/ttyUSB2-AT port for AT commands

4) /dev/ttyUSB3-Modem port for ppp-dial

5) /dev/ttyUSB4-audio port

6) /dev/ttyUSB5-Virtual Net card

插上U盘，提示设备运行：

[75097.986054] usb 2-1: New USB device found, idVendor=058f, idProduct=6387

[75097.993167] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[75098.000689] usb 2-1: Product: Mass Storage

[75098.004995] usb 2-1: Manufacturer: Generic

[75098.009342] usb 2-1: SerialNumber: AC3DF2EE

[75098.024341] usb-storage 2-1:1.0: USB Mass Storage device detected

[75098.049922] scsi0 : usb-storage 2-1:1.0

lsusb命令查看结果：

Bus 001 Device 002: ID 1e0e:9001

Bus 002 Device 002: ID 058f:6387

Bus 001 Device 001: ID 1d6b:0002

Bus 002 Device 001: ID 1d6b:0002

5. 交叉编译PPP

参见：http://blog.sina.com.cn/s/blog_7880d3350102wb3e.html

6. 拨号脚本设置

[email protected]:/etc/ppp# vi gprs-connect-chat

#Chat script for China Mobile, used SIMCOM sim4100 TD module.

TIMEOUT 15

ABORT "DELAYED"

ABORT "BUSY"

ABORT "ERROR"

ABORT "NO DIALTONE"

ABORT "NO CARRIER"

TIMEOUT 40

‘‘ \rAT

OK ATS0=0

OK ATE0V1

OK AT+CGDCONT=1,"IP","CMNET"

OK AT+CGEQREQ=1,2,128,384,,,0,,,,,,

OK ATDT*99*1#

CONNECT

[email protected]:/etc/ppp/peers# vi gprsdial

#/etc/ppp/peers/gprsdial

# This is pppd script for China Mobile, used SIMCOM SIM7100 Module

# Usage: root>pppd call gprs

#Interface should be used is the interface which connects physics interface of S

/dev/ttyUSB3

115200

crtscts

modem

#noauth

debug

nodetach

#hide-password

usepeerdns

noipdefault

defaultroute

user "cmnet"

0.0.0.0:0.0.0.0

#ipcp-accept-local

#ipcp-accept-remote

#lcp-echo-failure 12

#lcp-echo-interval 3

#noccp

#novj

#novjccomp

#persist

connect ‘/usr/sbin/chat -s -v -f /etc/ppp/gprs-connect-chat‘

#disconnect ‘/bin/chat -v -f /etc/ppp/gprs-disconnect-chat‘

6. 拨号

[email protected]: pppd call gprsdial

6. 测试

拨号之后进行测试，发现可以ping通ip但是无法ping通域名。这需要设置/etc/resolv.conf来添加DNS解析服务器的地址

文件/etc/resolv.conf配置DNS客户，它包含了主机的域名搜索顺序和DNS服务器的地址，每一行应包含一个关键字和一个或多个的由空格隔开的参数。下面是一个例子文件：

domain test.com

search www.test.com test.com

nameserver 202.96.128.86

nameserver 202.96.128.166

nameserver   #定义DNS服务器的IP地址

domain       #定义本地域名

search       #定义域名的搜索列表

sortlist     #对返回的域名进行排序

主要是nameserver关键字，如果没指定nameserver就找不到DNS服务器，其它关键字是可选的。

我这里只设置了两个DNS，如下：

ameserver 114.114.114.114

nameserver 8.8.8.8

参考文档：

How to use the SIM7100 module in Linux.pdf

http://blog.csdn.net/hanmengaidudu/article/details/17099737

http://www.linuxidc.com/Linux/2011-03/33430p2.htm

http://www.linuxidc.com/Linux/2011-03/33430.htm