Use driver writing to control high and low levels

Please read my first two articles:
[1] Allwinner orangepi-zeor2 driver writing
[2] Detailed explanation of driver function framework

Retrieve key information from chip manual

Know the GPIO base address
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, know the PC offset address,

and know the information about the port you want to control.

Know how data bits operate
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Code practice

driver code

#include <linux/fs.h>               //file_operations声明
#include <linux/module.h>           //module_init module_exit声明
#include <linux/init.h>             //__init__exit 宏声明
#include <linux/device.h>           //class device 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 *pin5_class;
static struct device *pin5_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="pin5";   //模块名

volatile unsigned int* GPIOBASE =  NULL;
volatile unsigned int* GPIOPC   =  NULL;
volatile unsigned int* GPIODAT  =  NULL;


        
//ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
static ssize_t pin5_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
    
    
        printk("pin5_read\n");
        return 0;
}

static int pin5_open(struct inode *inode,struct file *file)
{
    
    

        printk("pin5_open\n");      //内核打印函数，和printf类似

        *GPIOPC &= ~(0x6 << 20);         //把bit22~bit20 配置成001 ，为输出模式
        *GPIOPC |= (0x1 << 20);

        return 0;
}

static ssize_t pin5_write(struct file *file,const char __user *buf,size_t count, loff_t *ppos)
{
    
    
        char user_cmd;

      printk("pin5_write\n");

        //获取用户空间write的值
        copy_from_user(&user_cmd,buf,count);

        //根据值来操控io口，高电平或者低电平
        if(user_cmd == '1'){
    
    
                *GPIODAT |= 0x01 << 5;
                printk("pin5_set\n");
        }else if(user_cmd == '0'){
    
    
                *GPIODAT &= ~(0x01 << 5);
                printk("pin5_reset\n");
        }else{
    
    
                printk("undo\n");
        }
static struct file_operations pin5_fops = {
    
    
        .owner = THIS_MODULE,
        .open  = pin5_open,
        .write = pin5_write,
        .read  = pin5_read,
};
//static int __init
static int  pin5_drv_init(void)
{
    
    
        int ret;
        devno = MKDEV(major,minor);             //创建设备号
        ret   = register_chrdev(major, module_name,&pin5_fops);         //注册驱动 告诉内核 把这个驱动加入到>内核链表当中

        pin5_class=class_create(THIS_MODULE,"myfirstdemo");             //让代码在dev自动生成设备
        pin5_class_dev =device_create(pin5_class,NULL,devno,NULL,module_name);          //创建设备文件


        //映射虚拟地址
        //GPIO基地址
        GPIOBASE =  (volatile unsigned int *)ioremap(0x0300B000,4);
        //GPIOPC地址
        GPIOPC   =  (volatile unsigned int *)ioremap(0x0300B048,4);
        //GPIO数据地址
        GPIODAT  =  (volatile unsigned int *)ioremap(0x0300B058,4);
        return 0;
}

static void pin5_drv_exit(void)
{
    
    
        iounmap(GPIOBASE);
        iounmap(GPIOPC);
        iounmap(GPIODAT);

        device_destroy(pin5_class,devno);
        class_destroy(pin5_class);
        unregister_chrdev(major, module_name);
}

module_init(pin5_drv_init);
module_exit(pin5_drv_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("SHUN-GE");

User space test code

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main()
{
    
    
    int fd;
    int cmd;
    fd = open("/dev/pin5",O_RDWR);
    if(fd < 0){
    
    
        printf("open fail\n");
    }else {
    
    
        printf("open success\n");
    }
    scanf("%d",&cmd);
    if(cmd == 1){
    
    
        fd = write(fd,"1",1);
        printf("%d=cmd \n",cmd);
    }else if(cmd == 0){
    
    
        fd = write(fd,"0",1);
        printf("%d=cmd \n",cmd);
    }
}

Results display

PC5 is in OUT mode, the level is 1
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PC5 is in OUT mode, the level is low

Finish

If you have any questions, please feel free to raise them and make progress together.

Allwinner orangepi-zero2 driver writing 2, control level