//他操作上要兼顾各种设备

//下面我们介绍下tty_driver结构和tty_struct 结构。tty_driver表示一个具体的tty设备的驱动程序，而tty_struct 表示tty设备在

//具体的分析中介绍其成员。

struct tty_driver {
int magic; /* magic number for this structure */
struct kref kref; /* Reference management */
struct cdev cdev;//可见tty设备驱动是一个字符设备设备驱动
struct module *owner;
const char *driver_name;//这里是指驱动程序的名字
const char *name;//tty设备的命名相关
int name_base; /* offset of printed name */
int major; /* major device number */
int minor_start; /* start of minor device number */
int minor_num; /* number of *possible* devices */
int num; /* number of devices allocated */
short type; /* type of tty driver */
short subtype; /* subtype of tty driver */
struct ktermios init_termios; /* Initial termios */
int flags; /* tty driver flags */
struct proc_dir_entry *proc_entry; /* /proc fs entry */
struct tty_driver *other; /* only used for the PTY driver */

/*
* Pointer to the tty data structures
*/
struct tty_struct **ttys;//驱动操作的具体tty设备
struct ktermios **termios;
struct ktermios **termios_locked;
void *driver_state;

/*
* Driver methods
*/

const struct tty_operations *ops;
struct list_head tty_drivers; //用于链接tty驱动全局链表
};