【Rayeager PX2】PX2上使用GPIO口的例程
发布时间：2015-7-8 17:28
发布者：穿prada的008
关键词：
GPIO
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之前楼主在论坛中已经分享了简单驱动的编写，现在楼主再来教刚接触板子的新手们如何引用调用GPIO，不过这里楼主并没有将GPIO口的函数封装成库，然后在eclipse上调用，楼主这边的例子，只是简单的用adb工具进入板中，然后用一个测试程序使用端口，有兴趣想要在安卓界面调用端口的，可以参考楼主之前写的那编jni调用的帖子。 首先我们依旧来简单地说下步骤， 1.在/kernel/drivers下建个文件夹，自己创建并添加Kconfig和makefile，内容如下， 
2.在该目录下写个gpio驱动，内容在最后 3.返回drivers目录，在目录下修改Kconfig和makefile,修改内容如下 
4.进入内核，打开已写好的驱动。 
驱动内容如下， /*********************************************************************************** * driver for GPIO * **********************************************************************************/ #include #include #include #include #include #include #include #include #include #include #define DEVICE_NAME "rkpx2_GPIO" //定义设备名 #define RKPX2_GPIO_MAJOR 101 //定义设备号 static struct class *dev_class//定义设备结构体 static int gpio_open(struct inode *inode, struct file *file) { int i int err i=0 err = gpio_request(RK30_PIN4_PD1, "GPIO4_D1")//申请端口gpio4_1，成功返回0,失败返回负的错误值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D1 \n") return err }//若申请失败，则报错，然后推出， err = gpio_request(RK30_PIN4_PD2, "GPIO4_D2")//申请端口gpio4_2，成功返回0,失败返回负的错误值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D2 \n") return err } err = gpio_request(RK30_PIN4_PD3, "GPIO4_D3")//申请端口gpio4_3，成功返回0,失败返回负的错误值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D3 \n") return err } err = gpio_request(RK30_PIN4_PD4, "GPIO4_D4")//申请端口gpio4_4，成功返回0,失败返回负的错误值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D4 \n") return err } printk(KERN_INFO "RK_PX2 GPIO opened 4 !\n") gpio_direction_output(RK30_PIN4_PD1,1)//决定GPIO的方向，为输出 gpio_direction_output(RK30_PIN4_PD2,1) gpio_direction_output(RK30_PIN4_PD3,1) gpio_direction_output(RK30_PIN4_PD4,1) return 0 } static int gpio_close(struct inode *inode, struct file *file) { gpio_free(RK30_PIN4_PD1) gpio_free(RK30_PIN4_PD2) gpio_free(RK30_PIN4_PD3) gpio_free(RK30_PIN4_PD4) //释放端口， printk(KERN_INFO "RK_PX2 GPIO driver successfully close\n") return 0 } static int gpio_read(struct file *file, char *buffer, size_t size, loff_t *pos) //从内核中读取GPIO引脚的值 { int ret char key_buf[4] if (gpio_get_value(RK30_PIN4_PD1)==0){ key_buf[0]=0 }else{ key_buf[0]=1 } if (gpio_get_value(RK30_PIN4_PD2)==0){ key_buf[1]=0 }else{ key_buf[1]=1 } if (gpio_get_value(RK30_PIN4_PD3)==0){ key_buf[2]=0 }else{ key_buf[2]=1 } if (gpio_get_value(RK30_PIN4_PD4)==0){ key_buf[3]=0 }else{ key_buf[3]=1 } ret=copy_to_user(buffer,key_buf,4)//拷贝数据到用户区 ，成功为 0,失败为字节数 return ret } static long gpio_ioctl(struct file *file ,unsigned int cmd,unsigned long arg){ switch(cmd){//改变引脚的电平值 case 00: gpio_set_value(RK30_PIN4_PD1,0) printk("GPIO_D1 is low!\n") break case 01: gpio_set_value(RK30_PIN4_PD1,1) printk("GPIO_D1 is high!\n") break case 10: gpio_set_value(RK30_PIN4_PD2,0) printk("GPIO_D2 is low!\n") break case 11: gpio_set_value(RK30_PIN4_PD2,1) printk("GPIO_D2 is high!\n") break case 20: gpio_set_value(RK30_PIN4_PD3,0) printk("GPIO_D3 is low!\n") break case 21: gpio_set_value(RK30_PIN4_PD3,1) printk("GPIO_D3 is high!\n") break case 30: gpio_set_value(RK30_PIN4_PD4,0) printk("GPIO_D4 is low!\n") break case 31: gpio_set_value(RK30_PIN4_PD4,1) printk("GPIO_D4 is high!\n") break } return 0 } /*驱动接口设置*/ static struct file_operations dev_fops = { .owner = THIS_MODULE, //.unlocked_ioctl = tq210_gpio_ioctl, .open = gpio_open, .release = gpio_close, .read = gpio_read, .unlocked_ioctl = gpio_ioctl, } /*初始化设备，配置对应的IO，以及注册设备*/ static int __init dev_init(void) { int ret ret=0 ret = register_chrdev(RKPX2_GPIO_MAJOR,"rkpx2_GPIO",&dev_fops)//注册 if (ret<0) { printk("rkpx2 GPIO for test unable to get major%d \n",ret) return ret } dev_class = class_create(THIS_MODULE,"rkpx2_GPIO")//初始化 if (IS_ERR(dev_class)){ unregister_chrdev(RKPX2_GPIO_MAJOR,"rkpx2_GPIO") return PTR_ERR(dev_class) } device_create(dev_class,NULL,MKDEV(RKPX2_GPIO_MAJOR,0),NULL,"rkpx2_GPIO")//创建设备 printk(KERN_INFO "RKPX2 GPIO driver successfully probed!\n") return ret } /*注销设备*/ static void __exit dev_exit(void) { //misc_deregister(&dev_misc) gpio_free(RK30_PIN4_PD1) gpio_free(RK30_PIN4_PD2) gpio_free(RK30_PIN4_PD3) gpio_free(RK30_PIN4_PD4) printk(KERN_INFO "RKPX2 gpio driver successfully exit\n") } module_init(dev_init) module_exit(dev_exit) MODULE_AUTHOR("Rayeager cyl") MODULE_DESCRIPTION("rkpx2 gpio Driver") MODULE_LICENSE("GPL") 然后测试程序内容如下： #include #include #include #include #define DEVICE_NAME "/dev/rkpx2_GPIO" #define LED_OFF 0 #define LED_ON 1 int main(int argc,char **argv){ int fd int ret int flag int pin int ch printf("\n start test gpio_drivers\n") if(strcmp(argv[1],"open")==0){ fd=open(DEVICE_NAME,O_RDWR) if (fd==-1){ printf("open devices %s error\n",DEVICE_NAME) } printf("input the pin you want to operate") scanf("%d",&pin) printf("\n") printf("it will be set ?(1=on or 0=off):") scanf("%d",&ch) switch(pin){ case 0: (ch==1?ioctl(fd,1):ioctl(fd,2))break case 1: (ch==1?ioctl(fd,3):ioctl(fd,4))break case 2: (ch==1?ioctl(fd,5):ioctl(fd,6))break case 3: (ch==1?ioctl(fd,7):ioctl(fd,8))break } } if(strcmp(argv[1],"close")==0){ fd=open(DEVICE_NAME,O_RDWR) close(fd) } return 0 } Android.mk的内容 LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_SRC_FILES:=\ test.c LOCAL_MODULE:=gpioapp include$(BUILD_EXECUTABLE) 编译测试程序的方法:在源码任意位置建个目录，把Android.mk和测试程序全扔进去，然后执行mm（现在根目录执行source build/envsetup.sh） 实际操作，过程就不说了，亲测可行，正常操作的端口为GPIO4_1234 |
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