注册字符设备使用gpio设备树节点控制led三盏灯的亮灭

head.h

#define LED_ON _IOW('l',1,int *)
#define LED_OFF _IOW('l',0,int *)

text.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"
 
int main(int argc,const char * argv[])
{
    int a;
    int b;
    
 
    while(1)
    {          
        int fd;
        //从中断获取我们想实现的功能功能
        printf("请选择要控制的灯:0-LED1,1-LED2,2-LED3\n");
        scanf("%d",&a);
        switch(a)
        {   
            case 1:
            fd = open("/dev/mycdev0",O_RDWR);
            break;
            case 2:
            fd = open("/dev/mycdev1",O_RDWR);
            break;
            case 3:
            fd = open("/dev/mycdev2",O_RDWR);
            break;
        }
        if(fd<0)
        {
            printf("打开设备文件失败\n");
            return -1;
        }
        printf("打开设备文件成功\n");
 
        printf("请输入想要实现的功能 ");
        printf("0(关灯)1(开灯)\n");
        printf("请输入:");
        scanf("%d",&b);
 
        switch (b)
        {
            case 1:
            ioctl(fd,LED_ON,&b);
            break;
            case 0:
            ioctl(fd,LED_OFF,&b);
            break;
        }
        close(fd);
    }
    
 
    return 0;
}

demo.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/kdev_t.h>
#include "head.h"
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
struct cdev* cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
struct class* cls;
struct device *dev;
 
struct device_node *dnode;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
 
int mycdev_open(struct inode * inode,struct file* file)
{
    unsigned int min=MINOR(inode->i_rdev);//获取打开的文件的次设备号
    file->private_data=(void *)min;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
 
ssize_t mycdev_read(struct file * file,char *ubuf,size_t size,loff_t *lof)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
ssize_t mycdev_write(struct file * file,const char *ubuf,size_t size,loff_t *lof)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
 
int mycdev_close(struct inode * indode,struct file* file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
long mycdev_ioctl(struct file *file,unsigned int cmd,unsigned long arg)
{
    int min=(int)file->private_data;//获取文件的次设备号
    
    switch(min)
    {
        case 0://LED1
        switch(cmd)
        {
            case LED_ON://开灯
            gpiod_set_value(gpiono1,1);
            break;
            case LED_OFF://关灯
            gpiod_set_value(gpiono1,0);
            break;
        }
        break;
        case 1://LED2
        switch(cmd)
        {
            case LED_ON://开灯
            gpiod_set_value(gpiono2,1);
            break;
            case LED_OFF://关灯
            gpiod_set_value(gpiono2,0);
            break;
        }
        break;
        case 2://LED3
        switch(cmd)
        {
            case LED_ON://开灯
            gpiod_set_value(gpiono3,1);
            break;
            case LED_OFF://关灯
            gpiod_set_value(gpiono3,0);
            break;
        }
        break;
    }
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
 
}
 
struct file_operations fops = {
    .open=mycdev_open,
    .read=mycdev_read,
    .write=mycdev_write,
    .unlocked_ioctl = mycdev_ioctl,
    .release=mycdev_close,
};
 
static int __init mycdev_init(void)
{
    //1.申请一个对象空间cdev_alloc
    int ret;
    cdev=cdev_alloc();
    if(cdev==NULL)
    {
        printk("申请字符设备驱动对象空间失败\n");
        ret =-EFAULT;
        goto out1;
    }
    printk("申请字符设备驱动对象空间成功\n");
    //2.初始化对象cdev_init
    cdev_init(cdev,&fops);
    //3.申请设备号  register_chrdev_region()/alloc_chrdev_region()
    if(major==0)//动态申请
    {
        ret=alloc_chrdev_region(&devno,minor,3,"mychrdev");
        if(ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major=MAJOR(devno);//根据设备号获取主设备号
        minor=MINOR(devno);//根据设备号获取次设备号
    }
    else//静态申请
    {
        ret=register_chrdev_region(MKDEV(major,minor),3,"mychrdev");
        if(ret)
        {
            printk("静态申请设备号失败\n");
            goto out2;
        }
    }
    printk("设备号申请成功\n");
    //4.注册驱动对象  cdev_add
    ret=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");
    //5.向上提交目录  class_create
    cls=class_create(THIS_MODULE,"mychrdev");
    if(IS_ERR(cls))
    {
        printk("想上提交目录失败\n");
        goto out4;
    }
    printk("想上提交目录成功\n");
    //6.向上提交设备节点信息  device_create
    int i;
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"mycdev%d",i);
        if(IS_ERR(dev))
        {
            printk("想上提交设备节点失败\n");
            goto out5;
        }
    }
    printk("想上提交设备节点成功\n");   
 
    //使用gpio驱动
    dnode=of_find_node_by_path("/myled");
    if(dnode==NULL)
    {
        printk("解析设备树节点失败\n");
        return -ENXIO;
    }
    //获取led1 gpio编号
    gpiono1=gpiod_get_from_of_node(dnode,"led1-gpio",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono1))
    {
        printk("申请gpio信息失败\n");
        return -PTR_ERR(gpiono1);
    }
    //获取led2 gpio编号
    gpiono2=gpiod_get_from_of_node(dnode,"led2-gpio",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono2))
    {
        printk("申请gpio信息失败\n");
        return -PTR_ERR(gpiono2);
    }
    //获取led3 gpio编号
    gpiono3=gpiod_get_from_of_node(dnode,"led3-gpio",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono3))
    {
        printk("申请gpio信息失败\n");
        return -PTR_ERR(gpiono3);
    }
    //初始化为0
    gpiod_set_value(gpiono1,0);
    gpiod_set_value(gpiono2,0);
    gpiod_set_value(gpiono3,0);
 
    return 0;
out5:
    //当提交设备节点中途失败时，将提交成功的节点释放
    for(i--;i>=0;i--)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //销毁目录
    class_destroy(cls);
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major,minor),3);
out2:
    kfree(cdev);
out1:
    return ret;
    
}
 
static void __exit mycdev_exit(void)
{
    int i;
    //1.销毁设备节点信息
    for(i=0;i<3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //2.销毁目录
    class_destroy(cls);
    //3.注销字符设备驱动对象
    cdev_del(cdev);
    //4.释放设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
    //5.释放申请到的字符设备驱动对象空间
    kfree(cdev);
    //释放GPIO编号
    gpiod_put(gpiono1);
    gpiod_put(gpiono2);
    gpiod_put(gpiono3);
 
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");