//pin4driver2.c(底层代码)
#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 devise声明
#include <linux/uaccess.h> //copy_from_user 的头文件
#include <linux/types.h> //设备号 dev_t 类型声明
#include <asm/io.h> //ioremap 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
volatile unsigned int *GPFSEL0 = NULL;
volatile unsigned int *GPSET0 = NULL;
volatile unsigned int *GPCLR0 = NULL;
static int pin4_read(struct file *file,char __user *buf,size_t count,loff_t *ppos)
{
printk("pin4_read\n");
return 0;
}
//pin4_open函数
static int pin4_open(struct inode *inode,struct file *file)
{
printk("pin4_open\n"); //内核的打印函数和printf类似
//配置pin4引脚为输出引脚,bit 12~14 配置成001
*GPFSEL0 &= ~(0x6 << 12); //把 bit14,bit13 配置成0
*GPFSEL0 |= (0x1 << 12); //把 bit12 配置成1
return 0;
}
//pin4_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
if(userCmd == 1){
printk("set 1\n");
*GPSET0 |= (0x1 << 4);
}else if(userCmd == 0){
printk("set 0\n");
*GPCLR0 |= (0x1 << 4);
}else{
printk("undo\n");
}
return 0;
}
static struct file_operations pin4_fops = { //在keil的编译环境下不允许这样写,在linux下可以这样写
.owner = THIS_MODULE,
.open = pin4_open,
.write = pin4_write,
.read = pin4_read,
};
int __init pin4_drv_init(void) //真实驱动入口
{
int ret;
devno = MKDEV(major,minor); //创建设备号
ret = register_chrdev(major, module_name,&pin4_fops); //注册驱动 告诉内核,把这个驱动加入到内核驱动的链表中
pin4_class=class_create(THIS_MODULE,"myfirstdemo"); //让代码在dev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);//物理地址转化为虚拟地址,4:4个字节
GPSET0 = (volatile unsigned int *)ioremap(0x3f20001c,4);
GPCLR0 = (volatile unsigned int *)ioremap(0x3f200028,4);
return 0;
}
void __exit pin4_drv_exit(void)
{
iounmap(GPFSEL0);//对地址映射解除绑定
iounmap(GPSET0);
iounmap(GPCLR0);
device_destroy(pin4_class,devno);
class_destroy(pin4_class);
unregister_chrdev(major, module_name); //卸载驱动
}
module_init(pin4_drv_init); //入口,内核加载该驱动的时候,这个宏会被调用
module_exit(pin4_drv_exit);
MODULE_LICENSE("GPL v2");
//pin4test.c(上层代码)
#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("reason:");
}else{
printf("open success\n");
}
printf("input commend : 1/0 \n1:set pin4 high\n0:set pin4 low\n");
scanf("%d",&cmd);
if(cmd == 1){
data = 1;
}
if(cmd == 0){
data = 0;
}
printf("data = %d\n",data);//这句没写上层会出现小bug
fd = write(fd,&data,1);
return 0;
}