在ARM Linux上實現4G模塊PPP撥號上網

在ARM平台上實現4G模塊的PPP撥號上網，參考網上的資料和自己的理解，從一無所知到開發完成花了一周多。最後看到ARM板ping通www.linuxidc.com時甚是高興，現將此過程整理如下。當然，除此之外要做的工作還有很多。

4G模塊使用的SIMTECH 的SIM7100C，SIM7100C帶有UART和USB接口，在考慮速度上我們使用USB接口和ARM進行通信。所以向linux內核添加3G模塊的驅動(USB轉串口驅動)和PPP協議的支持，然後編譯內核並下載到開發板。

1. 編譯內核

◇ 大容量存儲驅動

> Device Drivers > USB support

make ARCH=arm menuconfig配置USB驅動：

<*> USB Mass Storage support

[*] USB Mass Storage verbose debug

<*> Realtek Card Reader support

[*] Realtek Card Reader autosuspend support

<*> Datafab Compact Flash Reader support

◇ USB驅動

> 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驅動

> 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. 交叉編譯libusb

下載usblib庫和libusb-compat

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

root@linuxidc:/opt/usb-tools/libusb-1.0.20# mkdir install

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

root@linuxidc:/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@linuxidc:/opt/usb-tools/libusb-1.0.20# make

root@linuxidc:/opt/usb-tools/libusb-1.0.20# make install

添加環境變量 http://www.linuxidc.com/Linux/2011-03/33432.htm（PKG_CONFIG_PATH設置）

root@linuxidc:/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@linuxidc:/opt/usb-tools/libusb-1.0.20# echo $PKG_CONFIG_PATH

編譯libusb-compat：

root@linuxidc:/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@linuxidc:/opt/usb-tools/libusb-compat-0.1.5# make

root@linuxidc:/opt/usb-tools/libusb-compat-0.1.5# make install

將生成的libusb-1.0.20和libusb-compat-0.1.5下的庫文件復制到ARM板上的linux的/lib下面即可。

3. 交叉編譯4G模塊驅動

交叉編譯GobiSerial.c(ARCH=arm CC=arm-none-linux-gnueabi-gcc)，得到GobiSerial.ko。復制到ARM板安裝驅動

#insmod GobiSerial.ko

4. 查看驅動運行狀況

插上4G模塊，虛擬出6個ttyUSB，它們分別是：

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盤，提示設備運行：

[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命令查看結果：

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. 交叉編譯PPP

參見： http://www.linuxidc.com/Linux/2016-03/129580.htm

6. 撥號腳本設置

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. 撥號

root@am335x-evm: pppd call gprsdial

6. 測試

撥號之後進行測試，發現可以ping通ip但是無法ping通域名。這需要設置/etc/resolv.conf來添加DNS解析服務器的地址

文件/etc/resolv.conf配置DNS客戶，它包含了主機的域名搜索順序和DNS服務器的地址，每一行應包含一個關鍵字和一個或多個的由空格隔開的參數。下面是一個例子文件：

domain test.com

search www.test.com test.com

nameserver 202.96.128.86

nameserver 202.96.128.166

nameserver #定義DNS服務器的IP地址

domain #定義本地域名

search #定義域名的搜索列表

sortlist #對返回的域名進行排序

主要是nameserver關鍵字，如果沒指定nameserver就找不到DNS服務器，其它關鍵字是可選的。

我這裡只設置了兩個DNS，如下：

ameserver 114.114.114.114

nameserver 8.8.8.8

參考文檔：

http://www.linuxidc.com/Linux/2016-03/129579.htm

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

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