linux 字元設備驅動步驟
1. 創建設備結構體：
Struct XXX_dev
{
Struct cdev cdev;
Unsigned value;
/* other values */
};
2. 編寫設備初始化函數：
Int XXX_init(void);
a. 根據主設設備號創建設備：dev_t dev = MKDEV(XXX_major, 0);
b. 註冊創建的設備：
手動註冊result = register_chrdev_region(dev, 1, “DEVICE NAME”); or
自動註冊result = alloc_chrdev_region(&dev, 0, 1, “DEVICE NAME”);
c. 為註冊成功的設備分配內存：
XXX_devp = kmalloc(sizeof(struct XXX_dev), GFP_KERNEL);
d. 初始化註冊成功的內存：
Memset(XXX_devp, 0, sizeof(struct XXX_dev));
XXX_setup_cdev(XXX_devp, 0);
i. 初始化設備結構體的操作函數：
Struct XXX_dev *dev = XXX_devp;
Cdev_init(&dev -> cdev, &XXX_fops);
Dev -> cdev.owner = “THIS_MODULE”;
Dev -> cdev.ops = &XXX_fops;
ii. 初始化后將設備結構體加入設備中
Cdev_add(&dev -> cdev, devno, 1);
Struct file_operations XXX_fops =
{
.owner = THIS_MODULE,
.read = XXX_read, /* 函數指針*/
.write = XXX_write,
.ioctl = XXX_ioctl,
.open = XXX_open,
.release = XXX_release,
};
int XXX_open(struct inode *inode, struct file *filp)；
int XXX_release(struct inode *inode, struct file *filp)；
ssize_t XXX_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)；
ssize_t XXX_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)；
int XXX_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)；
3. 編寫設備註銷函數：
XXX_cleanup();
a. 刪除設備結構體：
Cdev_del(&XXX_devp -> cdev);
b. 釋放設備內存：
Kfree(XXX_devp);
c. 註銷設備
Unregister_chrdev_region(MKDEV(XXX_major, 0), 1);
4. 設備模塊與系統介面函數：
Module_init(XXX_init);
Module_exit(XXX_cleanup);
[火星人 ] linux字元設備驅動步驟已經有665次圍觀
