飛凌嵌入式ElfBoard ELF 1板卡-字符驅(qū)動之自動創(chuàng)建節(jié)點

static struct device *my_device;

{

int ret;

// 在這里執(zhí)行驅(qū)動程序的初始化操作

// 注冊字符設(shè)備驅(qū)動程序

ret = alloc_chrdev_region(&dev_num,0,1,DEVICE_NAME);

if (ret < 0) {

printk(KERN_ALERT "Failed to allocate device number: %dn", ret);

return ret;

}

major=MAJOR(dev_num); ??//獲取主設(shè)備號

minor=MINOR(dev_num); ??//獲取次設(shè)備號

printk(KERN_INFO "major number: %dn",major);

printk(KERN_INFO "minor number: %dn",minor);

my_cdev.owner = THIS_MODULE;

cdev_init(&my_cdev,&fops); ??//初始化字符設(shè)備結(jié)構(gòu)體

cdev_add(&my_cdev,dev_num,1); ??//將字符設(shè)備添加到內(nèi)核中

// 創(chuàng)建設(shè)備類

my_class = class_create(THIS_MODULE, "my_class");

if (IS_ERR(my_class)) {

pr_err("Failed to create classn");

return PTR_ERR(my_class);

}

// 創(chuàng)建設(shè)備節(jié)點并關(guān)聯(lián)到設(shè)備類

my_device = device_create(my_class, NULL, MKDEV(major, minor), NULL, DEVICE_NAME);

if (IS_ERR(my_device)) {

pr_err("Failed to create devicen");

class_destroy(my_class);

return PTR_ERR(my_device);

}

printk(KERN_INFO "Device registered successfully.n");

return 0;

}

dev_t dev, void *drvdata, const char *fmt, ...);

{

// 在這里執(zhí)行驅(qū)動程序的清理操作

// 銷毀設(shè)備節(jié)點

device_destroy(my_class, MKDEV(major, minor));

// 銷毀設(shè)備類

class_destroy(my_class);

// 刪除字符設(shè)備

cdev_del(&my_cdev);

// 注銷字符設(shè)備驅(qū)動程序

unregister_chrdev(0, DEVICE_NAME);

printk(KERN_INFO "Device unregistered.n");

}

#include <linux/fs.h> ??????????// 包含文件系統(tǒng)相關(guān)函數(shù)的頭文件

#include <linux/uaccess.h> ?????// 包含用戶空間數(shù)據(jù)訪問函數(shù)的頭文件

#include <linux/cdev.h> ????????//包含字符設(shè)備頭文件

#include <linux/device.h>

#define DEVICE_NAME "mydevice" ?// 設(shè)備名稱

static dev_t dev_num; ??//分配的設(shè)備號

struct ?cdev my_cdev; ?????????//字符設(shè)備指針

int major; ?//主設(shè)備號

int minor; ?//次設(shè)備號

static struct class *my_class;

static struct device *my_device;

static int device_open(struct inode *inode, struct file *file)

{

// 在這里處理設(shè)備打開的操作

printk(KERN_INFO "This is device_open.n");

return 0;

}

static int device_release(struct inode *inode, struct file *file)

{

// 在這里處理設(shè)備關(guān)閉的操作

printk(KERN_INFO "This is device_release.n");

return 0;

}

static ssize_t device_read(struct file *file, char __user *buffer, size_t length, loff_t *offset)

{

// 在這里處理設(shè)備讀取的操作

printk(KERN_INFO "This is device_read.n");

return 0;

}

static ssize_t device_write(struct file *file, const char __user *buffer, size_t length, loff_t *offset)

{

// 在這里處理設(shè)備寫入的操作

printk(KERN_INFO "This is device_write.n");

return 0;

}

static struct file_operations fops = {

.owner = THIS_MODULE,

.open = device_open,

.release = device_release,

.read = device_read,

.write = device_write,

};

static int __init mydevice_init(void)

{

int ret;

// 在這里執(zhí)行驅(qū)動程序的初始化操作

// 注冊字符設(shè)備驅(qū)動程序

ret = alloc_chrdev_region(&dev_num,0,1,DEVICE_NAME);

if (ret < 0) {

printk(KERN_ALERT "Failed to allocate device number: %dn", ret);

return ret;

}

major=MAJOR(dev_num); ??//獲取主設(shè)備號

minor=MINOR(dev_num); ??//獲取次設(shè)備號

printk(KERN_INFO "major number: %dn",major);

printk(KERN_INFO "minor number: %dn",minor);

my_cdev.owner = THIS_MODULE;

cdev_init(&my_cdev,&fops); ??//初始化字符設(shè)備結(jié)構(gòu)體

cdev_add(&my_cdev,dev_num,1); ??//將字符設(shè)備添加到內(nèi)核中

// 創(chuàng)建設(shè)備類

my_class = class_create(THIS_MODULE, "my_class");

if (IS_ERR(my_class)) {

pr_err("Failed to create classn");

return PTR_ERR(my_class);

}

// 創(chuàng)建設(shè)備節(jié)點并關(guān)聯(lián)到設(shè)備類

my_device = device_create(my_class, NULL, MKDEV(major, minor), NULL, DEVICE_NAME);

if (IS_ERR(my_device)) {

pr_err("Failed to create devicen");

class_destroy(my_class);

return PTR_ERR(my_device);

}

printk(KERN_INFO "Device registered successfully.n");

return 0;

}

static void __exit mydevice_exit(void)

{

// 在這里執(zhí)行驅(qū)動程序的清理操作

// 銷毀設(shè)備節(jié)點

device_destroy(my_class, MKDEV(major, minor));

// 銷毀設(shè)備類

class_destroy(my_class);

// 刪除字符設(shè)備

cdev_del(&my_cdev);

// 注銷字符設(shè)備驅(qū)動程序

unregister_chrdev(0, DEVICE_NAME);

printk(KERN_INFO "Device unregistered.n");

}

module_init(mydevice_init);

module_exit(mydevice_exit);

MODULE_LICENSE("GPL"); ?????// 指定模塊的許可證信息

MODULE_AUTHOR("Your Name"); // 指定模塊的作者信息

MODULE_DESCRIPTION("A simple character device driver"); // 指定模塊的描述信息

elf@ubuntu:~/work/test/02_字符驅(qū)動/mydevice-auto$ make

#include <stdlib.h>

#include <unistd.h>

#include <sys/ioctl.h>

#include <errno.h>

#include <fcntl.h>

#define DEV_NAME "/dev/my_device"

int main(int argc, char *argv[])

{

int reg;

int fd = 0;

int dat = 0;

fd = open (DEV_NAME, O_RDWR);

if (fd < 0) {

perror("Open "DEV_NAME" Failed!n");

exit(1);

}

reg = read(fd, &dat, 1);

if (reg<0) {

perror("read "DEV_NAME" Failed!n");

exit(1);

}

dat = 0;

reg = write(fd, &dat, 1);

if (reg<0) {

perror("write "DEV_NAME" Failed!n");

exit(1);

}

close(fd);

return 0;

}

major number: 245

minor number: 0

Device registered successfully.

root@ELF1:~# ls /dev/my_device

/dev/my_device

root@ELF1:~#?./device-auto_app

This is device_open.

This is device_read.

This is device_write.

This is device_release.

root@ELF1:~# rmmod mydevice-auto.ko

Device unregistered.