Linux驱动编程字符驱动-0x00

#include<linux/module.h>#include<linux/kernel.h>#include<linux/fs.h>#include<linux/cdev.h>#include<linux/uaccess.h>#include<linux/slab.h>#define DEVICE_NAME "mychardev"// 设备名称#define DEVICE_SIZE  1024            // 设备虚拟内存大小static struct cdev my_cdev;static dev_t dev_num;static char *device_memory;// 打开设备staticintmy_open(struct inode *inode, struct file *filp){    printk(KERN_INFO "Device opened\n");    filp->private_data = device_memory;    return 0;}// 释放设备staticintmy_release(struct inode *inode, struct file *filp){    printk(KERN_INFO "Device released\n");    return 0;}// 从设备读取数据staticssize_tmy_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos){    size_t bytes_read = 0;    char *data = filp->private_data;    if (count > DEVICE_SIZE - *f_pos) {        count = DEVICE_SIZE - *f_pos;    }    if (copy_to_user(buf, data + *f_pos, count)) {        return -EFAULT;    }    bytes_read = count;    *f_pos += bytes_read;    return bytes_read;}// 向设备写入数据staticssize_tmy_write(struct file *filp, constchar __user *buf, size_t count, loff_t *f_pos){    size_t bytes_written = 0;    char *data = filp->private_data;    if (count > DEVICE_SIZE - *f_pos) {        count = DEVICE_SIZE - *f_pos;    }    if (copy_from_user(data + *f_pos, buf, count)) {        return -EFAULT;    }    bytes_written = count;    *f_pos += bytes_written;    return bytes_written;}// 文件操作结构体static struct file_operations my_fops = {   .owner   = THIS_MODULE,   .open    = my_open,   .release = my_release,   .read    = my_read,   .write   = my_write,};// 驱动模块初始化函数staticint __init my_driver_init(void){    int ret;    // 分配设备号 动态分配 1 个字符设备编号，次设备号从 0 开始    ret = alloc_chrdev_region(&dev_num, 0, 1, DEVICE_NAME);    if (ret < 0) {        printk(KERN_ERR "Failed to allocate device number\n");        return ret;    }    printk(KERN_INFO "Allocated character device region: major=%d, minor=%d\n", MAJOR(dev_num), MINOR(dev_num));    // 初始化字符设备    cdev_init(&my_cdev, &my_fops);    my_cdev.owner = THIS_MODULE;    // 添加字符设备到系统    ret = cdev_add(&my_cdev, dev_num, 1);    if (ret < 0) {        printk(KERN_ERR "Failed to add cdev\n");        unregister_chrdev_region(dev_num, 1);        return ret;    }    // 分配设备内存    device_memory = kmalloc(DEVICE_SIZE, GFP_KERNEL);    if (!device_memory) {        printk(KERN_ERR "Failed to allocate device memory\n");        cdev_del(&my_cdev);        unregister_chrdev_region(dev_num, 1);        return -ENOMEM;    }    printk(KERN_INFO "My character device driver loaded successfully\n");    return 0;}// 驱动模块退出函数staticvoid __exit my_driver_exit(void){    kfree(device_memory);    cdev_del(&my_cdev);    unregister_chrdev_region(dev_num, 1);    printk(KERN_INFO "My character device driver unloaded\n");}module_init(my_driver_init);module_exit(my_driver_exit);MODULE_AUTHOR("axun");MODULE_DESCRIPTION("A simple character device driver");MODULE_LICENSE("GPL");