如果是自己开发的板子，需要用GPIO引脚控制3G模块开机/关机时，下面的文章会对你有所帮助，是以处理器IMX6和中兴MG3732模块为例介绍。

一、引脚连接

       处理器的gpio3_GPIO[9]连接3G模块的ON/OFF（29）引脚来控制3G的开机/关机。

二、开关机条件

       给ON/OFF引脚连续2500~3500毫秒低电平则开机，给再ON/OFF引脚连续2500~3500毫秒低电平则关机。

三、gpio驱动程序

       gpio_3g.c 

#include<linux/module.h>#include<linux/kernel.h>#include<linux/init.h>#include<linux/fs.h>#include<linux/cdev.h>#include<linux/device.h>#include<asm/io.h>#include<linux/mm.h>#include<asm/uaccess.h>#include<linux/gpio.h>#define GPIO_IOF_MAGIC 0xd0#define 3G_INPUT	    _IO(GPIO_IOF_MAGIC,8)#define 3G_OUTPUT   	_IO(GPIO_IOF_MAGIC,9)#define 3G_ON_OFF		IMX_GPIO_NR(3,9)    //控制引脚为：gpio3[9]MODULE_LICENSE ("GPL");int gpio_major=2555;int gpio_minor=0;int number_devices=1;struct cdev gpiocdev;struct class *my_class;static int gpio_open(struct inode *inode,struct file *file){	printk (KERN_INFO "GPIO device opened\n");		if(gpio_direction_output(3G_ON_OFF,0x00)<0){		printk("3G_ON_OFF set direction failed\n");	}  	return 0;}static long gpio_ioctl(struct file *file,unsigned int cmd,unsigned long arg){	int val;	printk("GPIO:ioctl running....\n");		switch(cmd){		case 3G_INPUT:			if(gpio_direction_input(3G_ON_OFF)<0){				printk("3G_ON_OFF set input failed\n");			}			if(arg>0){				gpio_set_value(3G_ON_OFF,0x01);			}else{				gpio_set_value(3G_ON_OFF,0x00);			}			val=gpio_get_value(3G_ON_OFF);			printk("3G_ON_OFF ioctl val=%d\n",val);		break;		case 3G_OUTPUT:			if(gpio_direction_output(3G_ON_OFF,0x00)<0){				printk("3G_ON_OFF set direction failed\n");			}			if(arg>0){				gpio_set_value(3G_ON_OFF,0x01);			}else{				gpio_set_value(3G_ON_OFF,0x00);			}			val=gpio_get_value(3G_ON_OFF);			printk("3G_ON_OFF ioctl val=%d\n",val);		break;				default:			printk("cmd is not exist\n");			return -1;	}	return val;}static int gpio_release (struct inode *inode, struct file *file){	printk (KERN_INFO "GPIO device closed\n");  	return 0;}struct file_operations gpio_fops = {	.owner=THIS_MODULE,	.open=gpio_open,	.release=gpio_release,	.unlocked_ioctl=gpio_ioctl,};static void char_reg_setup_cdev (void){	int error;	dev_t devno;	devno=MKDEV(gpio_major,gpio_minor);	cdev_init(&gpiocdev,&gpio_fops);	gpiocdev.owner=THIS_MODULE;	error=cdev_add(&gpiocdev,devno,1);	if (error)		printk(KERN_NOTICE "Error %d adding char device GPIO",error);}static int __init gpio_init (void){	int result;	dev_t devno;	devno=MKDEV(gpio_major,gpio_minor);	if(gpio_major){		result=register_chrdev_region(devno,number_devices,"gpio_3g");	}else{		result=alloc_chrdev_region(&devno,0,number_devices,"gpio_3g");		gpio_major=MAJOR(devno);	}	if (result<0){		printk(KERN_WARNING "GPIO:can't get major number %d\n", gpio_major);		return result;	}	char_reg_setup_cdev ();		my_class=class_create(THIS_MODULE,"GPIOCLASS");	device_create(my_class,NULL,MKDEV(gpio_major,gpio_minor),NULL,"gpio_3g");	if(gpio_request(3G_ON_OFF,"UnKnow")<0){		printk("3G_ON_OFF request failed\n");	}	printk (KERN_INFO "char device GPIO registered\n");	return 0;}static void __exit gpio_exit(void){	dev_t devno=MKDEV(gpio_major,gpio_minor);	gpio_free(3G_ON_OFF);	cdev_del(&gpiocdev);	unregister_chrdev_region(devno,number_devices);	device_destroy(my_class,devno);	class_destroy(my_class);	printk(KERN_INFO"char device GPIO  unregister\n");}module_init (gpio_init);module_exit (gpio_exit);

四、内核添加gpio驱动步骤（android4.3源码）

      1、把gpio_3g.c放到~/myandroid/kernel_imx/drivers/char目录下（假设源码在~/myandroid下）。

      2、~/myandroid/kernel_imx/drivers/char/Konfig中最后添加红色框部分语句。

      3、在~/myandroid/kernel_imx/drivers/char/Makefile中添加红色框部分语句。

      4、在~/myandroid/kernel_imx下 make  menuconfig 来配置内核，配置完成后退出并保存。如下图：

      5、在进入~/myandroid/kernel_imx目录执行：

            cp  .config   arch/arm/configs/imx6_android_defconfig

            到此后，行以下命令编译：

             source build/enevsetup.sh

             lunch sabresb_6dq-user

             make

五、编译3G模块开关机程序

      1、程序代码

       3g_on_off.c  

#include<stdio.h>#include<unistd.h>#include<fcntl.h>#include<errno.h>#include<sys/ioctl.h>#include<sys/types.h>#define 3G_INPUT     _IO(GPIO_IOF_MAGIC,8)#define 3G_OUTPUT    _IO(GPIO_IOF_MAGIC,9)#define SET_ON           0x01#define SET_OFF          0x00int main(int argc, char *argv[]){	int fd;	fd=open("/dev/gpio_3g",O_RDWR); //打开gpio_3g设备文件	if(fd<0){		perror("open:");	}	if(ioctl(fd,3G_OUTPUT,SET_ON)<0){ //设置该引脚为输出高		perror("3G_OUTPUT ioctl:");	}	sleep(3);	if(ioctl(fd,3G_OUTPUT,SET_OFF)<0){ //设置该引脚为输出低		perror("3G_OUTPUT ioctl:");	}		if(ioctl(fd,3G_INPUT,SET_OFF)<0){ //设置该引脚为输入，防止被意外篡改		perror("3G_INPUT ioctl:");	}	close(fd);	return 0;}

       Android.mk   

LOCAL_PATH	:=$(call my-dir)include	$(CLEAR_VARS)LOCAL_MODULE_TAGES	:=optionalLOCAL_MODULE	:=3g_on_offLOCAL_SRC_FILES	:=3g_on_off.cinclude	$(BUILD_EXECUTABLE)

      2、在~/myandroid/external下创建 3g_on_off文件夹

      3、把 3g_on_off.c 和 Android.mk 文件放到新建文件夹下。

      4、执行以下命令编译：

            source  build/enevsetup.sh

            lunch  sabresb_6dq-user

            mmm  external/3g_on_off

      5、把生成的可执行程序：

            ~/myandroid/out/target/product/sabresd_6dq/obj/EXECUTABLES/3g_on_off_intermediates/3g_on_off放到

            ~/myandroid/out/target/product/sabresd_6dq/system里面

            执行：make  snod   打包

六、烧写镜像到开发板，执行3g_on_off程序对3G模块进行开关机操作。

android下调试3G之gpio控制3G上电