在ARM-linux上完成4G模块PPP拨号上网

在ARM平台上完结4G模块的PPP拨号上网，参阅网上的材料和自己的了解，从一窍不通到开发完结花了一周多。最终看到ARM板ping通www.baidu.com时甚是快乐，现将此进程收拾如下。当然，除此之外要做的作业还有许多。
4G模块运用的SIMTECH 的SIM7100C，SIM7100C带有UART和USB接口，在考虑速度上咱们运用USB接口和ARM进行通讯。所以向linux内核增加3G模块的驱动(USB转串口驱动)和PPP协议的支撑，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装备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. 穿插编译libusb
下载usblib库和libusb-compat
https://sourceforge.net/projects/libusb/files/
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# mkdir install
configure: error: “udev support requested but libudev not installed“(处理：增加–disable-udev)
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# ./configure –host=arm-none-linux-gnueabi –prefix=/opt/usb-tools/libusb-1.0.20/install –disable-udev
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# make
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# make install

增加环境变量 http://www.linuxidc.com/Linux/2011-03/33432.htm（PKG_CONFIG_PATH设置）
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# export PKG_CONFIG_PATH=/opt/usb-tools/libusb-1.0.20/install/lib/pkgconfig:$PKG_CONFIG_PATH
root@zhaoxc-VBox:/opt/usb-tools/libusb-1.0.20# echo $PKG_CONFIG_PATH

编译libusb-compat：
root@zhaoxc-VBox:/opt/usb-tools/libusb-compat-0.1.5# ./configure –host=arm-none-linux-gnueabi –prefix=/opt/usb-tools/libusb-compat-0.1.5/install
root@zhaoxc-VBox:/opt/usb-tools/libusb-compat-0.1.5# make
root@zhaoxc-VBox:/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. 穿插编译4G模块驱动
穿插编译GobiSerial.c(ARCH=arm CC=arm-none-linux-gnueabi-gcc)，得到GobiSerial.ko。复制到ARM板装置驱动
#insmod GobiSerial.ko

4. 检查驱动运转状况
插上4G模块，虚拟出6个ttyUSB，它们分别是：
root@am335x-evm:/# 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，提示设备运转：
[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指令检查成果：
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. 穿插编译PPP
拜见：http://blog.sina.com.cn/s/blog_7880d3350102wb3e.html

6. 拨号脚本设置
root@am335x-evm:/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
root@am335x-evm:/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
root@am335x-evm: pppd call gprsdial

6. 测验
拨号之后进行测验，发现能够ping通ip可是无法ping通域名。这需求设置/etc/resolv.conf来增加DNS解析服务器的地址
文件/etc/resolv.conf装备DNS客户，它包括了主机的域名查找次序和DNS服务器的地址，每一行应包括一个关键字和一个或多个的由空格离隔的参数。下面是一个比如文件：
domain test.com
search www.test.com test.com
nameserver 202.96.128.86
nameserver 202.96.128.166
nameserver #界说DNS服务器的IP地址
domain #界说本地域名
search #界说域名的查找列表
sortlist #对回来的域名进行排序
主要是nameserver关键字，假如没指定nameserver就找不到DNS服务器，其它关键字是可选的。
我这儿只设置了两个DNS，如下：
ameserver 114.114.114.114
nameserver 8.8.8.8

参阅文档：
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