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之前樓主在論壇中已經分享了簡單驅動的編寫，現在樓主再來教剛接觸板子的新手們如何引用調用GPIO，不過這里樓主并沒有將GPIO口的函數封裝成庫，然后在eclipse上調用，樓主這邊的例子，只是簡單的用adb工具進入板中，然后用一個測試程序使用端口，有興趣想要在安卓界面調用端口的，可以參考樓主之前寫的那編jni調用的帖子。 首先我們依舊來簡單地說下步驟， 1.在/kernel/drivers下建個文件夾，自己創建并添加Kconfig和makefile，內容如下， 
2.在該目錄下寫個gpio驅動，內容在最后 3.返回drivers目錄，在目錄下修改Kconfig和makefile,修改內容如下
4.進入內核，打開已寫好的驅動。
驅動內容如下， /*********************************************************************************** * driver for GPIO * **********************************************************************************/ #include #include #include #include #include #include #include #include #include #include #define DEVICE_NAME "rkpx2_GPIO" //定義設備名 #define RKPX2_GPIO_MAJOR 101 //定義設備號 static struct class *dev_class//定義設備結構體 static int gpio_open(struct inode *inode, struct file *file) { int i int err i=0 err = gpio_request(RK30_PIN4_PD1, "GPIO4_D1")//申請端口gpio4_1，成功返回0,失敗返回負的錯誤值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D1 \n") return err }//若申請失敗，則報錯，然后推出， err = gpio_request(RK30_PIN4_PD2, "GPIO4_D2")//申請端口gpio4_2，成功返回0,失敗返回負的錯誤值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D2 \n") return err } err = gpio_request(RK30_PIN4_PD3, "GPIO4_D3")//申請端口gpio4_3，成功返回0,失敗返回負的錯誤值 if(err) { printk(KERN_ERR "RK_PX2 failed to request GPIO4_D3 \n") return err } err = gpio_request(RK30_PIN4_PD4, "GPIO4_D4")//申請端口gpio4_4，成功返回0,失敗返回負的錯誤值 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)//決定GPIO的方向，為輸出 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) //釋放端口， 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) //從內核中讀取GPIO引腳的值 { 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)//拷貝數據到用戶區 ，成功為 0,失敗為字節數 return ret } static long gpio_ioctl(struct file *file ,unsigned int cmd,unsigned long arg){ switch(cmd){//改變引腳的電平值 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 } /*驅動接口設置*/ 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, } /*初始化設備，配置對應的IO，以及注冊設備*/ static int __init dev_init(void) { int ret ret=0 ret = register_chrdev(RKPX2_GPIO_MAJOR,"rkpx2_GPIO",&dev_fops)//注冊 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")//創建設備 printk(KERN_INFO "RKPX2 GPIO driver successfully probed!\n") return ret } /*注銷設備*/ 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") 然后測試程序內容如下： #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的內容 LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_SRC_FILES:=\ test.c LOCAL_MODULE:=gpioapp include$(BUILD_EXECUTABLE) 編譯測試程序的方法:在源碼任意位置建個目錄，把Android.mk和測試程序全扔進去，然后執行mm（現在根目錄執行source build/envsetup.sh） 實際操作，過程就不說了，親測可行，正常操作的端口為GPIO4_1234 |
