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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 * void (*set_termios)(struct tty_struct *tty, struct termios * old);
63 *
64 * This function notifies the line discpline that a change has
65 * been made to the termios structure.
66 *
67 * int (*poll)(struct tty_struct * tty, struct file * file,
68 * poll_table *wait);
69 *
70 * This function is called when a user attempts to select/poll on a
71 * tty device. It is solely the responsibility of the line
72 * discipline to handle poll requests.
73 *
74 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
75 * char *fp, int count);
76 *
77 * This function is called by the low-level tty driver to send
78 * characters received by the hardware to the line discpline for
79 * processing. <cp> is a pointer to the buffer of input
80 * character received by the device. <fp> is a pointer to a
81 * pointer of flag bytes which indicate whether a character was
82 * received with a parity error, etc.
83 *
84 * int (*receive_room)(struct tty_struct *);
85 *
86 * This function is called by the low-level tty driver to
87 * determine how many characters the line discpline can accept.
88 * The low-level driver must not send more characters than was
89 * indicated by receive_room, or the line discpline may drop
90 * those characters.
91 *
92 * void (*write_wakeup)(struct tty_struct *);
93 *
94 * This function is called by the low-level tty driver to signal
95 * that line discpline should try to send more characters to the
96 * low-level driver for transmission. If the line discpline does
97 * not have any more data to send, it can just return.
98 *
99 * int (*hangup)(struct tty_struct *)
100 *
101 * Called on a hangup. Tells the discipline that it should
102 * cease I/O to the tty driver. Can sleep. The driver should
103 * seek to perform this action quickly but should wait until
104 * any pending driver I/O is completed.
105 */
106
107#include <linux/fs.h>
108#include <linux/wait.h>
109
110struct tty_ldisc {
111 int magic;
112 char *name;
113 int num;
114 int flags;
115
116 /*
117 * The following routines are called from above.
118 */
119 int (*open)(struct tty_struct *);
120 void (*close)(struct tty_struct *);
121 void (*flush_buffer)(struct tty_struct *tty);
122 ssize_t (*chars_in_buffer)(struct tty_struct *tty);
123 ssize_t (*read)(struct tty_struct * tty, struct file * file,
124 unsigned char __user * buf, size_t nr);
125 ssize_t (*write)(struct tty_struct * tty, struct file * file,
126 const unsigned char * buf, size_t nr);
127 int (*ioctl)(struct tty_struct * tty, struct file * file,
128 unsigned int cmd, unsigned long arg);
129 void (*set_termios)(struct tty_struct *tty, struct termios * old);
130 unsigned int (*poll)(struct tty_struct *, struct file *,
131 struct poll_table_struct *);
132 int (*hangup)(struct tty_struct *tty);
133
134 /*
135 * The following routines are called from below.
136 */
137 void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
138 char *fp, int count);
139 int (*receive_room)(struct tty_struct *);
140 void (*write_wakeup)(struct tty_struct *);
141
142 struct module *owner;
143
144 int refcount;
145};
146
147#define TTY_LDISC_MAGIC 0x5403
148
149#define LDISC_FLAG_DEFINED 0x00000001
150
151#define MODULE_ALIAS_LDISC(ldisc) \
152 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
153
154#endif /* _LINUX_TTY_LDISC_H */