1 #ifndef _LINUX_TTY_LDISC_H
2 #define _LINUX_TTY_LDISC_H
3
4 /*
5 * This structure defines the interface between the tty line discpline
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 discpline is associated
13 * with the tty. The line discpline 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 discpline is being
19 * shutdown, either because the tty is being closed or because
20 * the tty is being changed to use a new line discpline
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 * iscpline 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 discpline 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 discpline 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. Not 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 stucture.
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
100 #include <linux/fs.h>
101 #include <linux/wait.h>
102
103 struct tty_ldisc {
104 int magic;
105 char *name;
106 int num;
107 int flags;
108 /*
109 * The following routines are called from above.
110 */
111 int (*open)(struct tty_struct *);
112 void (*close)(struct tty_struct *);
113 void (*flush_buffer)(struct tty_struct *tty);
114 ssize_t (*chars_in_buffer)(struct tty_struct *tty);
115 ssize_t (*read)(struct tty_struct * tty, struct file * file,
116 unsigned char * buf, size_t nr);
117 ssize_t (*write)(struct tty_struct * tty, struct file * file,
118 const unsigned char * buf, size_t nr);
119 int (*ioctl)(struct tty_struct * tty, struct file * file,
120 unsigned int cmd, unsigned long arg);
121 void (*set_termios)(struct tty_struct *tty, struct termios * old);
122 unsigned int (*poll)(struct tty_struct *, struct file *,
123 struct poll_table_struct *);
124
125 /*
126 * The following routines are called from below.
127 */
128 void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
129 char *fp, int count);
130 int (*receive_room)(struct tty_struct *);
131 void (*write_wakeup)(struct tty_struct *);
132 };
133
134 #define TTY_LDISC_MAGIC 0x5403
135
136 #define LDISC_FLAG_DEFINED 0x00000001
137
138 #endif /* _LINUX_TTY_LDISC_H */
139
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