Linux 驱动 操控IO端 编写代码
作者：互联网
pin4driver.c
#include <linux/fs.h> //file_operations声明
#include <linux/module.h> //module_init module_exit声明
#include <linux/init.h> //_init _exit 宏定义声明
#include <linux/device.h> //class device声明
#include <linux/uaccess.h> //class
#include <linux/types.h>
#include <asm/io.h> //ioreamap.iounmap的头文件
static struct class *pin4_class;
static struct device *pin4_class_dev;
static dev_t devno; //设备号
static int major = 231; //主设备号
static int minor = 0; //次设备号
static char *module_name = "pin4";//模块名
//整数11
//0xb 11 00010001
//对应 真实驱动入口
volatile unsigned int* GPFSEL0 = NULL;//volatile (unsigned int *) 0x3f200000;
volatile unsigned int* GPSET0 = NULL;//volatile (unsigned int *) 0x3f20001C;
volatile unsigned int* GPCLR0 = NULL;//volatile (unsigned int *) 0x3f200028;
//led_read函数
static int pin4_read (struct file *file1, char __user *buf, size_t size,loff_t *ppos)
{
printk("pin4_read\n");//内核打印函数
return 0;
}
//led_open函数
static int pin4_open(struct inode *inode,struct file *file)
{
printk("pin4_open\n");
//配置pin4 引脚为输出引脚 bit 12 - 14配置成001
*GPFSEL0 &= ~(0x6 << 12); //按位与 把bit 14 13 配置成 0
*GPFSEL0 |= (0x1 <<12);
return 0;
}
//led_write函数
static ssize_t pin4_write (struct file *file,const char __user *buf, size_t count, loff_t *ppos)
{
int userCmd;
printk("pin4_write\n");
//获取上层write函数的值
copy_from_user(&userCmd,buf,count);
//根据值来操作io口 高电平 或者低电平
//printk("get value\n");
if(userCmd == 1){
printk("set 1\n");
*GPSET0 |= 0x1 << 4;
}else if(userCmd == 0){
printk("set 0\n");
*GPCLR0 |= 0x1 <<4;
}else{
printk("dont do\n");
}
return 0;
}
static struct file_operations pin4_fops = {
.owner = THIS_MODULE,
.open = pin4_open,
.write = pin4_write,
.read = pin4_read,
};
int __init pin4_drv_init(void) //1.真实驱动入口
{
int ret;
printk("insmod driver pin4 success\n");
devno = MKDEV(major,minor); //2.创建设备号
ret = register_chrdev(major,module_name,&pin4_fops); //3.注册驱动 告诉内核，把这个驱动加入到内核的链表中
pin4_class = class_create( THIS_MODULE,"myfirstdemo"); //让代码再dev自动生成设备
pin4_class_dev = device_create(pin4_class,NULL,devno,NULL,module_name); //创建设备文件
GPFSEL0 = (volatile unsigned int *) ioremap(0x3f200000,4);//将物理地址转换为虚拟地址，把io口寄存器映射成普通内存单元进行访问
GPSET0 = (volatile unsigned int *) ioremap(0x3f20001C,4);
GPCLR0 = (volatile unsigned int *) ioremap(0x3f200028,4);
return 0;
}
void __exit pin4_drv_exit(void)
{
iounmap(GPFSEL0); //接触绑定映射
iounmap(GPSET0);
iounmap(GPCLR0);
device_destroy(pin4_class,devno);
class_destroy(pin4_class);
unregister_chrdev(major, module_name); // 卸载驱动
}
pin4test.c
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
int main()
{
int fd;
int cmd;
int data;
fd = open("/dev/pin4",O_RDWR);
if(fd < 0){
printf("open failed\n");
perror("reson:");
}else{
printf("open success\n");
}
printf("input commnd : 1/0 \n 1:set pin4 high\n 0:set pin4 low\n");
scanf("%d",&cmd);
if(cmd == 1){
data = 1;
}
if(cmd == 0){
data = 0;
}
printf("data = %d\n",data);
fd = write(fd,&data,1);
}
按照这个流程
去观察 gpio readall 的引脚状态
标签：操控,int,unsigned,static,IO,Linux,volatile,include,pin4 来源： https://blog.csdn.net/weixin_46016743/article/details/113195643