点灯实验（字符设备驱动的注册+GPIO子系统）

内核文件：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/ioctl.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include "myled.h"

int major, minor = 0;
struct cdev *cdev;
struct class *cls;
struct device *dev;
//定义一个指向设备节点的指针
struct device_node *node;
struct device_node *node_led;
struct property *pr; //属性结构体指针
int gpiono1;
struct gpio_desc *desc_led1;
struct gpio_desc *desc_led2;
struct gpio_desc *desc_led3;
int chdev_open(struct inode *inode, struct file *file)
{
    return 0;
}
int chdev_close(struct inode *inode, struct file *file)
{
    return 0;
}
ssize_t chdev_read(struct file *file, char __user *ubuf, size_t szie, loff_t *loff)
{
    return 0;
}
ssize_t chdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
    return 0;
}
long ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int ret, which;
    switch (cmd)
    {
    case LedOFF:
        ret = copy_from_user(&which, (void *)arg, sizeof(int));
        if (ret)
        {
            printk("用户向内核拷贝数据失败n");
            return -EIO;
        }
        switch (which)
        {
        case 1:
            gpiod_set_value(desc_led1, 0);
            break;
        case 2:
            gpiod_set_value(desc_led2, 0);
            break;
        case 3:
            gpiod_set_value(desc_led3, 0);
            break;
        }
        break;
    case LedON:
        ret = copy_from_user(&which, (void *)arg, sizeof(int));
        if (ret)
        {
            printk("用户向内核拷贝数据失败n");
            return -EIO;
        }
        switch (which)
        {
        case 1:
            gpiod_set_value(desc_led1, 1);
            break;
        case 2:
            gpiod_set_value(desc_led2, 1);
            break;
        case 3:
            gpiod_set_value(desc_led3, 1);
            break;
        }
        break;
    default:
        printk("功能码错误n");
        break;
    }
    return 0;
}
struct file_operations fops = {
    .open = chdev_open,
    .read = chdev_read,
    .write = chdev_write,
    .release = chdev_close,
    .unlocked_ioctl = ioctl,
};
static int __init mycdev_init(void)
{
    int ret;
    dev_t devno;
    cdev = cdev_alloc();
    if (NULL == cdev)
    {
        printk("初始化驱动设备对象失败n");
        ret = -ENOMEM;
        goto ERR1;
    }
    cdev_init(cdev, &fops);
    ret = alloc_chrdev_region(&devno, minor, 1, "my_led");
    if (ret)
    {
        printk("申请设备号失败n");
        goto ERR2;
    }
    major = MAJOR(devno);
    minor = MINOR(devno);
    ret = cdev_add(cdev, MKDEV(major, minor), 1);
    if (ret)
    {
        printk("字符设备驱动注册失败n");
        goto ERR3;
    }
    cls = class_create(THIS_MODULE, "chdev_led");
    if (IS_ERR(cls))
    {
        printk("向上提交节点失败n");
        goto ERR4;
    }
    dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "led");
    if (IS_ERR(dev))
    {
        printk("创建逻辑节点失败n");
        ret = PTR_ERR(dev);
        goto ERR5;
    }
    //根据设备节点路径获取设备节点信息
    node = of_find_node_by_path("/leds");
    if (node == NULL)
    {
        printk("获取节点信息失败n");
        return ENODATA;
    }
    node_led = of_get_child_by_name(node, "extend-leds");
    if (NULL == node_led)
    {
        printk("获取子节点失败n");
    }
    //获取gpio编号
    desc_led1 = gpiod_get_from_of_node(node_led, "led1", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(desc_led1))
    {
        printk("获取申请gpio编号失败n");
        return PTR_ERR(desc_led1);
    }
 
    desc_led2 = gpiod_get_from_of_node(node_led, "led2", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(desc_led1))
    {
        printk("获取申请gpio编号失败n");
        return PTR_ERR(desc_led1);
    }
 
    desc_led3 = gpiod_get_from_of_node(node_led, "led3", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(desc_led1))
    {
        printk("获取申请gpio编号失败n");
        return PTR_ERR(desc_led1);
    }
    return 0;
ERR5:
    device_destroy(cls, MKDEV(major, 0));
    class_destroy(cls);
ERR4:
    cdev_del(cdev);
ERR3:
    unregister_chrdev_region(MKDEV(major, minor), 1);
ERR2:
    kfree(cdev);
ERR1:
    return ret;
}
static void __exit mycdev_exit(void)
{
    //销毁设备节点
    device_destroy(cls, MKDEV(major, 0));
    class_destroy(cls);
    // 注销字符设备驱动
    cdev_del(cdev);
    // 释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 1);
    // 释放动态申请的空间
    kfree(cdev);
 
    gpiod_set_value(desc_led1, 0);
    gpiod_put(desc_led1);
    gpiod_set_value(desc_led2, 0);
    gpiod_put(desc_led2);
    gpiod_set_value(desc_led3, 0);
    gpiod_put(desc_led3);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用文件：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/time.h>
#include "myled.h"
 
int main(int argc, char const *argv[])
{
    int fd;
    char buf[128] = {};
    int which;
    fd = open("/dev/led", O_RDWR);
    if (fd < 0)
    {
        printf("打开文件失败n");
        exit(-1);
    }
    while (1)
    {
        printf("请输入控制命令1：开灯1 0：关灯n");
        fgets(buf, sizeof(buf), stdin);
        printf("请输入要操作的灯：1-》LED1  2->LED2 3->LED3n");
        scanf("%d", &which);
        getchar();
        //吃掉换行符
        buf[strlen(buf) - 1] = '';
        if (buf[0] == '1')
            ioctl(fd, LedON, &which);
        else
            ioctl(fd, LedOFF, &which);
    }
 
    close(fd);
    return 0;
}

最后

以上就是顺心乐曲为你收集整理的点灯实验（字符设备驱动的注册+GPIO子系统）的全部内容，希望文章能够帮你解决点灯实验（字符设备驱动的注册+GPIO子系统）所遇到的程序开发问题。

如果觉得靠谱客网站的内容还不错，欢迎将靠谱客网站推荐给程序员好友。