1#ifndef _LINUX_TTY_LDISC_H
2#define _LINUX_TTY_LDISC_H
3
4/*
5 * This structure defines the interface between the tty line discipline
6 * implementation and the tty routines.  The following routines can be
7 * defined; unless noted otherwise, they are optional, and can be
8 * filled in with a null pointer.
9 *
10 * int	(*open)(struct tty_struct *);
11 *
12 * 	This function is called when the line discipline is associated
13 * 	with the tty.  The line discipline can use this as an
14 * 	opportunity to initialize any state needed by the ldisc routines.
15 *
16 * void	(*close)(struct tty_struct *);
17 *
18 *	This function is called when the line discipline is being
19 * 	shutdown, either because the tty is being closed or because
20 * 	the tty is being changed to use a new line discipline
21 *
22 * void	(*flush_buffer)(struct tty_struct *tty);
23 *
24 * 	This function instructs the line discipline to clear its
25 * 	buffers of any input characters it may have queued to be
26 * 	delivered to the user mode process.
27 *
28 * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
29 *
30 * 	This function returns the number of input characters the line
31 *	discipline may have queued up to be delivered to the user mode
32 *	process.
33 *
34 * ssize_t (*read)(struct tty_struct * tty, struct file * file,
35 *		   unsigned char * buf, size_t nr);
36 *
37 * 	This function is called when the user requests to read from
38 * 	the tty.  The line discipline will return whatever characters
39 * 	it has buffered up for the user.  If this function is not
40 * 	defined, the user will receive an EIO error.
41 *
42 * ssize_t (*write)(struct tty_struct * tty, struct file * file,
43 * 		    const unsigned char * buf, size_t nr);
44 *
45 * 	This function is called when the user requests to write to the
46 * 	tty.  The line discipline will deliver the characters to the
47 * 	low-level tty device for transmission, optionally performing
48 * 	some processing on the characters first.  If this function is
49 * 	not defined, the user will receive an EIO error.
50 *
51 * int	(*ioctl)(struct tty_struct * tty, struct file * file,
52 * 		 unsigned int cmd, unsigned long arg);
53 *
54 *	This function is called when the user requests an ioctl which
55 * 	is not handled by the tty layer or the low-level tty driver.
56 * 	It is intended for ioctls which affect line discpline
57 * 	operation.  Note that the search order for ioctls is (1) tty
58 * 	layer, (2) tty low-level driver, (3) line discpline.  So a
59 * 	low-level driver can "grab" an ioctl request before the line
60 * 	discpline has a chance to see it.
61 *
62 * long	(*compat_ioctl)(struct tty_struct * tty, struct file * file,
63 * 		        unsigned int cmd, unsigned long arg);
64 *
65 *      Process ioctl calls from 32-bit process on 64-bit system
66 *
67 * void	(*set_termios)(struct tty_struct *tty, struct ktermios * old);
68 *
69 * 	This function notifies the line discpline that a change has
70 * 	been made to the termios structure.
71 *
72 * int	(*poll)(struct tty_struct * tty, struct file * file,
73 * 		  poll_table *wait);
74 *
75 * 	This function is called when a user attempts to select/poll on a
76 * 	tty device.  It is solely the responsibility of the line
77 * 	discipline to handle poll requests.
78 *
79 * void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
80 * 		       char *fp, int count);
81 *
82 * 	This function is called by the low-level tty driver to send
83 * 	characters received by the hardware to the line discpline for
84 * 	processing.  <cp> is a pointer to the buffer of input
85 * 	character received by the device.  <fp> is a pointer to a
86 * 	pointer of flag bytes which indicate whether a character was
87 * 	received with a parity error, etc.
88 *
89 * void	(*write_wakeup)(struct tty_struct *);
90 *
91 * 	This function is called by the low-level tty driver to signal
92 * 	that line discpline should try to send more characters to the
93 * 	low-level driver for transmission.  If the line discpline does
94 * 	not have any more data to send, it can just return.
95 *
96 * int (*hangup)(struct tty_struct *)
97 *
98 *	Called on a hangup. Tells the discipline that it should
99 *	cease I/O to the tty driver. Can sleep. The driver should
100 *	seek to perform this action quickly but should wait until
101 *	any pending driver I/O is completed.
102 */
103
104#include <linux/fs.h>
105#include <linux/wait.h>
106
107struct tty_ldisc {
108	int	magic;
109	char	*name;
110	int	num;
111	int	flags;
112
113	/*
114	 * The following routines are called from above.
115	 */
116	int	(*open)(struct tty_struct *);
117	void	(*close)(struct tty_struct *);
118	void	(*flush_buffer)(struct tty_struct *tty);
119	ssize_t	(*chars_in_buffer)(struct tty_struct *tty);
120	ssize_t	(*read)(struct tty_struct * tty, struct file * file,
121			unsigned char __user * buf, size_t nr);
122	ssize_t	(*write)(struct tty_struct * tty, struct file * file,
123			 const unsigned char * buf, size_t nr);
124	int	(*ioctl)(struct tty_struct * tty, struct file * file,
125			 unsigned int cmd, unsigned long arg);
126	long	(*compat_ioctl)(struct tty_struct * tty, struct file * file,
127				unsigned int cmd, unsigned long arg);
128	void	(*set_termios)(struct tty_struct *tty, struct ktermios * old);
129	unsigned int (*poll)(struct tty_struct *, struct file *,
130			     struct poll_table_struct *);
131	int	(*hangup)(struct tty_struct *tty);
132
133	/*
134	 * The following routines are called from below.
135	 */
136	void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
137			       char *fp, int count);
138	void	(*write_wakeup)(struct tty_struct *);
139
140	struct  module *owner;
141
142	int refcount;
143};
144
145#define TTY_LDISC_MAGIC	0x5403
146
147#define LDISC_FLAG_DEFINED	0x00000001
148
149#define MODULE_ALIAS_LDISC(ldisc) \
150	MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
151
152#endif /* _LINUX_TTY_LDISC_H */
153