Linux下GPRS拨号功能的实现

原文

第一步：编写GPRS的内核驱动程序

  因为我用的开发板基于ARM920T，linux内核中没有mc35i的驱动程序，所以自己写了个驱动程序，重新编译了内核。驱动程序代码如下：

/**//*
* 作者：龙涛
*/


#define __NO_VERSION__
#include <linux/module.h>
#include <linux/version.h>


#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/delay.h>
#include <linux/config.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/uaccess.h>


#undef  DEBUG_Mc35i
//#define DEBUG_Mc35i    1


#ifdef DEBUG_Mc35i
#define DBG_Mc35i(fmt, args...) printk(fmt,## args)
#else
#define DBG_Mc35i(fmt, args...)
#endif


static int Mc35i_open(struct inode *, struct file *);
static int Mc35i_close(struct inode *, struct file *);
static int Mc35i_read(struct file *, int *, size_t, loff_t *);
static int Mc35i_write(struct file *, const char *, size_t, loff_t *);
//static void Mc35i_interrupt(int, void *, struct pt_regs *);


static void Mc35i_hardware_init(void);


#define Mc35i_MAJOR     253


#define TRAN_CMD    1
#define TRAN_CMD_DATA    2
#define READ_CMD_DATA    3


/**//* User CMD */
#define CMD_IGT '0'
#define CMD_EMERGOFF '1'


/**//* PC14, PC15, PC5 for Mc35i */
#define MC35_IGT AT91C_PIO_PC14
#define MC35_EMERGOFF AT91C_PIO_PC15
#define MC35_ST AT91C_PIO_PC5


static struct file_operations Mc35i_fops = ...{
open:           Mc35i_open,
read:        Mc35i_read,
write:          Mc35i_write,
release:        Mc35i_close,
};


static int input_flag = 0;
static unsigned char input_data = 0xff;


static void Mc35i_hardware_init (void)
...{
    DBG_Mc35i("Mc35i_hardware_init ");


    AT91_SYS->PIOC_PER |= MC35_IGT | MC35_EMERGOFF|MC35_ST;


    AT91_SYS->PIOC_OER |= MC35_IGT | MC35_EMERGOFF;
    AT91_SYS->PIOC_ODR |= MC35_ST;
    AT91_SYS->PIOC_CODR |= MC35_IGT| MC35_EMERGOFF;                     //ignition when system init


}


static int Mc35i_open (struct inode *inode, struct file *file)
...{
    DBG_Mc35i("Mc35i_open ");


    MOD_INC_USE_COUNT;
    return 0;
}


static int Mc35i_close (struct inode *inode, struct file *file)
...{
    DBG_Mc35i("Mc35i_close ");


    MOD_DEC_USE_COUNT;    
    return 0;
}


static int Mc35i_read (struct file *file, int *buf, size_t count, loff_t *ppos)
...{
    unsigned int  data;


    DBG_Mc35i("Mc35i_read: input_flag %d ", input_flag);


    data = AT91_SYS->PIOC_PDSR & MC35_ST;
    printk("status of PC5 is %d ", data);
    put_user(data, buf);


    return count;
}


static int Mc35i_write (struct file *file, const char *buf, size_t count, loff_t *ppos)
...{
    unsigned char cmd_type;


    DBG_Mc35i("Mc35i_write: %p ", buf);


    get_user(cmd_type, buf);


    switch (cmd_type) ...{
        case CMD_IGT:
            AT91_SYS->PIOC_SODR |= MC35_IGT;          //enable /IGT
            mdelay(10);
            AT91_SYS->PIOC_CODR |= MC35_IGT;            //disable /IGT  
            mdelay(100);
            AT91_SYS->PIOC_SODR |= MC35_IGT;          //enable /IGT
            break;
        case CMD_EMERGOFF:
            AT91_SYS->PIOC_CODR |= MC35_EMERGOFF;    
            break;
        default:
            DBG_Mc35i("Mc35i_write: cmd_type = %d error ", cmd_type);
            break;
    }


    return count;
}




static void __init Mc35i_init (void)
...{
    //int ret;


    Mc35i_hardware_init();    


    if(register_chrdev(Mc35i_MAJOR, "Mc35i", &Mc35i_fops))...{
        DBG_Mc35i("register_chrdev for Mc35i error ");
        goto fail_register_chrdev;
    }
    printk(KERN_INFO __FILE__ ":  gprsMc35i for AT91RM9200 ");
    return;


    fail_register_chrdev:
    return;
}


static void __exit Mc35i_cleanup (void)
...{
    unregister_chrdev(Mc35i_MAJOR, "Mc35i");
    return;    
}


module_init(Mc35i_init);
module_exit(Mc35i_cleanup);

编译内核后，要在文件系统中创建设备，命令如下：
mknod Mc35i c 253 0

第二步：移植ppp协议

    由于arm-linux上没有提供使用ppp的pppd, chat应用程序，所以需要向开发板上移植。方法就和普通的应用程序一样，在pc机上的develop目录下面编译，然后将生成的可执行程序复制到Ramdisk文件系统中，在下次重新下载内核和文件系统时使用新的文件系统，就可以在arm-linux上运行pppd了。具体过程如下：
    1，在samba.org下载ppp-2.4.3.tar.gz后安如下操作：
      tar  zxvf ppp-2.4.3.tar.gz
    2，由于在ppp根文件夹目录下面没有makefile文件，所以要自己添加：

# PPP top-level Makefile for Linux.


DESTDIR = /usr/local
BINDIR = $(DESTDIR)/sbin
INCDIR = $(DESTDIR)/include
MANDIR = $(DESTDIR)/share/man
ETCDIR = /etc/ppp


# uid 0 = root
INSTALL= install


all:
    cd chat; $(MAKE) $(MFLAGS) all
    cd pppd/plugins; $(MAKE) $(MFLAGS) all
    cd pppd; $(MAKE) $(MFLAGS) all
    cd pppstats; $(MAKE) $(MFLAGS) all
    cd pppdump; $(MAKE) $(MFLAGS) all


install: $(BINDIR) $(MANDIR)/man8 install-progs install-devel


install-progs:
    cd chat; $(MAKE) $(MFLAGS) install
    cd pppd/plugins; $(MAKE) $(MFLAGS) install
    cd pppd; $(MAKE) $(MFLAGS) install
    cd pppstats; $(MAKE) $(MFLAGS) install
    cd pppdump; $(MAKE) $(MFLAGS) install


install-etcppp: $(ETCDIR) $(ETCDIR)/options $(ETCDIR)/pap-secrets 
    $(ETCDIR)/chap-secrets


install-devel:
    cd pppd; $(MAKE) $(MFLAGS) install-devel


$(ETCDIR)/options:
    $(INSTALL) -c -m 644 etc.ppp/options $@
$(ETCDIR)/pap-secrets:
    $(INSTALL) -c -m 600 etc.ppp/pap-secrets $@
$(ETCDIR)/chap-secrets:
    $(INSTALL) -c -m 600 etc.ppp/chap-secrets $@


$(BINDIR):
    $(INSTALL) -d -m 755 $@
$(MANDIR)/man8:
    $(INSTALL) -d -m 755 $@
$(ETCDIR):
    $(INSTALL) -d -m 755 $@


clean:
    rm -f `find . -name '*.[oas]' -print`
    rm -f `find . -name 'core' -print`
    rm -f `find . -name '*~' -print`
    cd chat; $(MAKE) clean
    cd pppd/plugins; $(MAKE) clean
    cd pppd; $(MAKE) clean
    cd pppstats; $(MAKE) clean
    cd pppdump; $(MAKE) clean


dist-clean:    clean
    rm -f Makefile `find . -name Makefile -print`


#kernel:
#    cd linux; ./kinstall.sh


# no tests yet, one day...
installcheck:
    true

         至于其他目录下的makefile可以复制该目录下的makefile.linux即可。交叉编译后得到chat、pppd、pppstats、pppdump四个应用程序，拷贝到嵌入式系统的文件系统ramdisk/target/usr/sbin目录下，权限改成755即可。
       然后在ramdisk/target/dev目录下建立ppp节点：
       mknod ppp -c 108,0
   运行PPPD看看， 若说segment fault, 则是内核没有配置mmap, 或者把刚才的Makefile中的 HAVE_MMAP改为FALSE, 因为pppd中调用了mmap().
   PPP拨号脚本有ppp-on:

#!/bin/sh
#
# Script to initiate a ppp connection. This is the first part of the
# pair of scripts. This is not a secure pair of scripts as the codes
# are visible with the 'ps' command.  However, it is simple.
#
# These are the parameters. Change as needed.
TELEPHONE=*99***1#    # The telephone number for the connection
ACCOUNT=        # The account name for logon (as in 'George Burns')
PASSWORD=        # The password for this account (and 'Gracie Allen')
LOCAL_IP=0.0.0.0    # Local IP address if known. Dynamic = 0.0.0.0
REMOTE_IP=0.0.0.0    # Remote IP address if desired. Normally 0.0.0.0
NETMASK=255.255.255.0    # The proper netmask if needed
#
# Export them so that they will be available at 'ppp-on-dialer' time.
export TELEPHONE ACCOUNT PASSWORD
# 
# This is the location of the script which dials the phone and logs
# in.  Please use the absolute file name as the $PATH variable is not
# used on the connect option.  (To do so on a 'root' account would be
# a security hole so don't ask.)
#
DIALER_SCRIPT=/mnt/ppp-on-dialer #这里改成自己文件所在的路径
#
# Initiate the connection
# 
# I put most of the common options on this command. Please, don't
# forget the 'lock' option or some programs such as mgetty will not
# work. The asyncmap and escape will permit the PPP link to work with
# a telnet or rlogin connection. You are welcome to make any changes
# as desired. Don't use the 'defaultroute' option if you currently
# have a default route to an ethernet gateway.
#
exec /usr/sbin/pppd debug lock modem /dev/ttyS1 19200 
    asyncmap 20A0000 escape FF kdebug 0 $LOCAL_IP:$REMOTE_IP 
    noipdefault netmask $NETMASK defaultroute connect $DIALER_SCRIPT

如果是Modem拨号，ppp-on为：

#!/bin/sh
#
# Script to initiate a ppp connection. This is the first part of the
# pair of scripts. This is not a secure pair of scripts as the codes
# are visible with the 'ps' command.  However, it is simple.
#
# These are the parameters. Change as needed.
TELEPHONE=016300    # The telephone number for the connection
ACCOUNT=163        # The account name for logon (as in 'George Burns')
PASSWORD=163        # The password for this account (and 'Gracie Allen')
LOCAL_IP=0.0.0.0    # Local IP address if known. Dynamic = 0.0.0.0
REMOTE_IP=0.0.0.0    # Remote IP address if desired. Normally 0.0.0.0
NETMASK=255.255.255.0    # The proper netmask if needed
#
# Export them so that they will be available at 'ppp-on-dialer' time.
export TELEPHONE ACCOUNT PASSWORD
# 
# This is the location of the script which dials the phone and logs
# in.  Please use the absolute file name as the $PATH variable is not
# used on the connect option.  (To do so on a 'root' account would be
# a security hole so don't ask.)
#
DIALER_SCRIPT=/mnt/ppp-on-dialer-modem
#
# Initiate the connection
# 
# I put most of the common options on this command. Please, don't
# forget the 'lock' option or some programs such as mgetty will not
# work. The asyncmap and escape will permit the PPP link to work with
# a telnet or rlogin connection. You are welcome to make any changes
# as desired. Don't use the 'defaultroute' option if you currently
# have a default route to an ethernet gateway.
#
exec /usr/sbin/pppd debug lock modem crtscts /dev/ttyS1 115200 
    asyncmap 20A0000 escape FF kdebug 0 $LOCAL_IP:$REMOTE_IP 
    noipdefault netmask $NETMASK defaultroute connect $DIALER_SCRIPT

GPRS的ppp-on-dialer脚本如下：

#!/bin/sh
#
# This is part 2 of the ppp-on script. It will perform the connection
# protocol for the desired connection.
#
exec chat -v                        
    TIMEOUT        3                
    ABORT        ' BUSY '            
    ABORT        ' NO ANSWER '            
    ABORT        ' RINGING RINGING '    
    ''         AT                
    TIMEOUT        30                
    OK        AT+CMEE=1            
    OK        AT+CGDCONT=1,"ip","cmnet"                
    OK        AT+CGATT=1  
    OK        ATDT*99***1#  
    CONNECT

Modem的ppp-on-dialer如下：

#!/bin/sh
#
# This is part 2 of the ppp-on script. It will perform the connection
# protocol for the desired connection.
#
exec chat -v                        
    TIMEOUT        3                
    ABORT        ' BUSY '            
    ABORT        ' NO ANSWER '            
    ABORT        ' RINGING RINGING '    
    ''         AT                
    TIMEOUT        30                
    OK        ATDT$TELEPHONE            
    sername:--sername:    $ACCOUNT            
    assword:    $PASSWORD

第三步：C程序的实现

//GPRS初始化
int InitGPRS(char *IP)
{    
    FILE *ppp0;
    int status;    
    char buf[100];
    int nIndex = 0;
    char *ch=NULL,*nlch=NULL;


    //判断是否存在IP
    status = system("ifconfig ppp0>/ppp0");    
    if(status == 127||status == -1||status != 0)
    {
        //打开设备
        if(confData->WorkType == TYPE_GPRS)
        {
            if ((mc35i = open("/dev/Mc35i",O_RDWR|O_NOCTTY))<0)
            {
                printf("Warning:Open GPRS Mc35i failed! ");
                return -1;
            }    
            else
            {
                printf("OK:Open GPRS is ok! ");
            }


            while(1) 
            { 
                nIndex++;
                if(nIndex > 30)
                    return -1;
                if (!GPRSPowerIsOn())
                {
                    printf("Warning:gprs power is not on! ");
                    write(mc35i,"0",1);   //ignition mc35i
                    sleep(2);
                }    
                else
                    break;
            }
        }


        //执行ppp拨号程序
        if (!vfork())
        {        
            //GPRS方式
            if(confData->WorkType == TYPE_GPRS)
            {
                printf("Exec GPRS ppp-on...... ");
                if(execl("./ppp-on","ppp-on",NULL)<0)    
                    //if (execvp("pppd",pppdScript)<0)
                {
                    printf("Exec ppp-on error:%s! ",strerror(errno));      
                    return -1;
                }
            }
            //MODEM方式
            else
            {
                printf("Exec MODEM ppp-on...... ");
                if(execl("./ppp-on-modem","ppp-on",NULL)<0)        
                {
                    printf("Exec ppp-on error:%s! ",strerror(errno));      
                    return -1;
                }            
            }
        }    
        sleep(40);    
        //获取分配的IP地址
        printf("Exec ifconfig ppp0 > ppp0...... ");
        status = system("ifconfig ppp0>/ppp0");    
        if(status == 127||status == -1||status != 0)
        {
            printf("Exec ifconfig ppp0 error! ");    
            GPRSPoweroff();
            return -1;    
        }
    }


    printf("Open file ppp0...... ");
    if ((ppp0 = fopen("/ppp0","r")) <= 0)
    {
        printf("Open ppp0 info file fail! ");        
        GPRSPoweroff();
        return -1;
    }    
    /*格式：
    # ifconfig ppp0
    ppp0      Link encap:Point-to-Point Protocol
    inet addr:211.74.48.254  P-t-P:211.74.48.1  Mask:255.255.255.255
    UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
    RX packets:5 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:3
    */
    if (fread(buf,sizeof(char),sizeof(buf),ppp0)>0)
    {
        printf("Get ppp0 IP...... ");
        ch = strchr(buf,' ');           
        ch = strchr(ch,':');
        nlch = strchr(ch,'P');
        memcpy(IP,++ch,(nlch-ch)-2);
     }