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驱动开发-day9,驱动开发

驱动代码：

#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
struct cdev* cdev;
unsigned int major = 500;
unsigned int minor = 0;
dev_t devno;
struct class* cls;
struct device* dev;
struct device_node* dnode;
struct device_node* dnode_led;
unsigned int irqno;
unsigned int number = 0;
// 定义等待队列头
wait_queue_head_t wq_head;
unsigned int condition = 0;
// 分配对象
struct work_struct work;
char kbuf[128] = { 0 };
struct gpio_desc* gpiono;
int mycdev_open(struct inode* inode, struct file* file)
{

    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)
{
    int ret;

    wait_event_interruptible(wq_head, condition);

    if (size > sizeof(number)) {
        size = sizeof(number);
    }

    ret = copy_to_user(ubuf, (void*)&number, size);
    if (ret) {
        printk("copy_to_user filed\n");
        return -EIO;
    }
    condition = 0;
    return size;
}
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* inode, 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)
{
    return 0;
}
struct file_operations fops = {
    .open = mycdev_open,
    .unlocked_ioctl = mycdev_ioctl,
    .read = mycdev_read,
    .write = mycdev_write,
    .release = mycdev_close,
};

// 中断触发函数
irqreturn_t myirq_handler(int irqno, void* dev_id)
{
    if (!gpio_get_value(gpiono)) {
        number = !number;
        gpiod_set_value(gpiono, number);
        condition = 1;
        wake_up_interruptible(&wq_head);
    }

    return IRQ_HANDLED;
}
// 解析led设备树
int myled_init(void)
{
    // 解析led灯的设备树节点
    dnode_led = of_find_node_by_path("/led_key");
    if (dnode_led == NULL) {
        printk("解析设备led树节点失败\n");
        return -ENXIO;
    }
    printk("解析设备树节点成功 \n");
    // 根据设备树节点解析led1gpio编号
    gpiono = gpiod_get_from_of_node(dnode_led, "led1-gpios", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono)) {
        printk("gpio编号解析失败\n");
        return -PTR_ERR(gpiono);
    }
    return 0;
}
// 解析按键设备树
int myirq_init(void)
{
    int wet;
    dnode = of_find_node_by_name(NULL, "led_key");
    if (dnode == NULL) {
        printk("解析设备树key节点失败\n");
        return -ENXIO;
    }
    printk("设备树节点解析成功\n");
    // 获取软中断号
    irqno = irq_of_parse_and_map(dnode, 0);
    if (!irqno) {
        printk("软中断号获取失败\n");
        return -ENOMEM;
    }
    printk("软中断号获取成功irqno=%d\n", irqno);
    // 注册中断
    wet = request_irq(irqno, myirq_handler, IRQF_TRIGGER_FALLING, "key1-gpios", NULL);
    if (wet) {
        printk("注册失败\n");
        return wet;
    }
    return 0;
}
static int __init mycdev_init(void)
{
    int ret, i;
    // 初始化等待队列头
    init_waitqueue_head(&wq_head);
    // 分配字符设备驱动对象空间
    cdev = cdev_alloc();
    if (cdev == NULL) {
        printk("申请字符设备驱动空间失败\n");
        ret = -EFAULT;
        goto out1;
    }
    // 字符设备驱动对象部分初始化
    cdev_init(cdev, &fops);
    // 静态申请设备号
    if (major > 0) {

        ret = register_chrdev_region(MKDEV(major, minor), 3, "mykey");
        if (ret) {
            printk("静态指定设备号失败\n");
            goto out2;
        }
    } else { // 动态申请设备号
        ret = alloc_chrdev_region(&devno, minor, 3, "mykey");
        if (ret) {
            printk("动态指定设备号失败\n");
            goto out2;
        }
        major = MAJOR(devno);
        minor = MINOR(devno);
    }
    // 注册字符设备驱动对象
    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");
    // 向上提交目录
    cls = class_create(THIS_MODULE, "mykey");
    if (IS_ERR(cls)) {
        printk("向上提交目录失败\n");
        ret = -PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");
    // 向上提交设备节点
    for (i = 0; i < 3; i++) {
        dev = device_create(cls, NULL, MKDEV(major, i), NULL, "mykey%d", i);
        if (IS_ERR(dev)) {
            printk("向上提交节点信息失败\n");
            ret = -PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备节点信息成功\n");

    // 解析设备树节点
    myled_init();
    // 解析设备树节点
    myirq_init();
    return 0;
out5:
    for (--i; i > 0; i--) {
        // 销毁提交的设备信息
        device_destroy(cls, MKDEV(major, i));
    }
    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)
{
    // 注销中断
    free_irq(irqno, NULL);
    // 销毁设备信息
    int i;
    for (i = 0; i < 3; i++) {
        device_destroy(cls, MKDEV(major, i));
    }
    // 销毁目录
    class_destroy(cls);
    // 注销对象
    cdev_del(cdev);
    // 释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
    // 释放对象空间
    kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

测试代码：文章来源地址https://www.toymoban.com/news/detail-554058.html


#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, char const* argv[])
{
    int fd;

    unsigned int number;
    
    fd = open("/dev/mykey0", O_RDWR);
    if (fd < 0) {
        printf("打开设备文件失败\n");
        exit(-1);
    }

    while (1) {

        read(fd, &number, sizeof(number));
        printf("number=:%d\n", number);
    }
    close(fd);
    return 0;
}

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