一. tty结构体

1.tty_driver

struct tty_driver {
	int	magic;
	struct kref kref;	//参考计数
	struct cdev cdev;	//字符设备
	struct module	*owner;	//模块所有者
	const char	*driver_name;	//驱动名
	const char	*name;	//设备名
	int	name_base;
	int	major;	//主设备号
	int	minor_start;	//起始次设备号
	int	minor_num;	//设备个数
	int	num;	//分配了的tty设备个数
	short	type;	//tty设备的类型
	short	subtype;	//tty设备子类型
	struct ktermios init_termios;	//初始化的ktermios
	int	flags;	//tty驱动标志
	struct proc_dir_entry *proc_entry;	//procfs入口
	struct tty_driver *other;
	struct tty_struct **ttys;
	struct ktermios **termios;
	struct ktermios **termios_locked;
	void *driver_state;
	const struct tty_operations *ops;	//操作函数集
	struct list_head tty_drivers;	//驱动链表
};

1.1 tty->flag

#define TTY_DRIVER_INSTALLED	0x0001
#define TTY_DRIVER_RESET_TERMIOS	0x0002
#define TTY_DRIVER_REAL_RAW		0x0004
#define TTY_DRIVER_DYNAMIC_DEV	0x0008
#define TTY_DRIVER_DEVPTS_MEM	0x0010
#define TTY_DRIVER_HARDWARE_BREAK	0x0020

1.2 tty->type tty设备类型

#define TTY_DRIVER_TYPE_SYSTEM	0x0001
#define TTY_DRIVER_TYPE_CONSOLE	0x0002
#define TTY_DRIVER_TYPE_SERIAL	0x0003
#define TTY_DRIVER_TYPE_PTY		0x0004
#define TTY_DRIVER_TYPE_SCC		0x0005	/* scc driver */
#define TTY_DRIVER_TYPE_SYSCONS	0x0006

2.ktermios结构体

struct ktermios {
	tcflag_t c_iflag;	/* input mode flags */	//输入模式标志
	tcflag_t c_oflag;	/* output mode flags */	//输出模式标志
	tcflag_t c_cflag;	/* control mode flags */	//控制模式标志
	tcflag_t c_lflag;	/* local mode flags */	//本地模式标志
	cc_t c_line;	/* line discipline */	//线路规程类型
	cc_t c_cc[NCCS];	/* control characters */	//控制字符
	speed_t c_ispeed;	/* input speed */		//输入速度
	speed_t c_ospeed;	/* output speed */		//输出速度
};

3.tty_struct

struct tty_struct {
	int	magic;	//魔数
	struct kref kref;	//参考计数
	struct device *dev;	//设备文件
	struct tty_driver *driver;	//tty驱动
	const struct tty_operations *ops;	//tty操作函数集
	int index;	
	struct mutex ldisc_mutex;
	struct tty_ldisc *ldisc;	//线路规程
	struct mutex termios_mutex;
	spinlock_t ctrl_lock;
	struct ktermios *termios, *termios_locked;
	struct termiox *termiox;
	char name[64];	//名字
	struct pid *pgrp;
	struct pid *session;
	unsigned long flags;
	int count;
	struct winsize winsize;
	unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
	unsigned char low_latency:1, warned:1;
	unsigned char ctrl_status;
	unsigned int receive_room;
	struct tty_struct *link;
	struct fasync_struct *fasync;
	struct tty_bufhead buf;
	int alt_speed;
	wait_queue_head_t write_wait;
	wait_queue_head_t read_wait;
	struct work_struct hangup_work;
	void *disc_data;
	void *driver_data;
	struct list_head tty_files;
#define N_TTY_BUF_SIZE 4096
	unsigned int column;
	unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
	unsigned char closing:1;
	unsigned char echo_overrun:1;
	unsigned short minimum_to_wake;
	unsigned long overrun_time;
	int num_overrun;
	unsigned long process_char_map[256/(8*sizeof(unsigned long))];
	char *read_buf;
	int read_head;
	int read_tail;
	int read_cnt;
	unsigned long read_flags[N_TTY_BUF_SIZE/(8*sizeof(unsigned long))];
	unsigned char *echo_buf;
	unsigned int echo_pos;
	unsigned int echo_cnt;
	int canon_data;
	unsigned long canon_head;
	unsigned int canon_column;
	struct mutex atomic_read_lock;
	struct mutex atomic_write_lock;
	struct mutex output_lock;
	struct mutex echo_lock;
	unsigned char *write_buf;
	int write_cnt;
	spinlock_t read_lock;
	struct work_struct SAK_work;
	struct tty_port *port;
};

4.tty_ldisc线路规程

struct tty_ldisc {
	struct tty_ldisc_ops *ops;
	atomic_t users;
};

4.1 线路规程操作函数集

struct tty_ldisc_ops {
	int	magic;
	char	*name;
	int	num;
	int	flags;
	int	(*open)(struct tty_struct *);
	void	(*close)(struct tty_struct *);