【Rayeager PX2】PX2上使用GPIO口的例程

穿prada的008

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 <linux/miscdevice.h>

#include <linux/input.h>

#include <linux/clk.h>

#include <linux/delay.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <linux/module.h>

#include <linux/init.h>

#include <mach/gpio.h>

#include <linux/gpio.h>

#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 ")

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 ")

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 ")

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 ")

return err

}

printk(KERN_INFO "RK_PX2 GPIO opened 4 ! ")

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 ")

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! ")

break

case 01: gpio_set_value(RK30_PIN4_PD1,1)

printk("GPIO_D1  is high! ")

break

case 10: gpio_set_value(RK30_PIN4_PD2,0)

printk("GPIO_D2  is low! ")

break

case 11: gpio_set_value(RK30_PIN4_PD2,1)

printk("GPIO_D2  is high! ")

break

case 20: gpio_set_value(RK30_PIN4_PD3,0)

printk("GPIO_D3  is low! ")

break

case 21: gpio_set_value(RK30_PIN4_PD3,1)

printk("GPIO_D3  is high! ")

break

case 30: gpio_set_value(RK30_PIN4_PD4,0)

printk("GPIO_D4  is low! ")

break

case 31: gpio_set_value(RK30_PIN4_PD4,1)

printk("GPIO_D4  is high! ")

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 ",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! ")

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 ")

}

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 <stdio.h>

#include <stdlib.h>

#include <fcntl.h>

#include <string.h>

#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(" start test gpio_drivers ")

if(strcmp(argv[1],"open")==0){

fd=open(DEVICE_NAME,O_RDWR)

if (fd==-1){

printf("open devices %s error ",DEVICE_NAME)

}

printf("input the pin you want to operate")

scanf("%d",&pin)

printf(" ")

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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