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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#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 *
Peter Hurley6be06e72013-03-06 08:38:21 -050012 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070016 * void (*close)(struct tty_struct *);
17 *
18 * This function is called when the line discipline is being
Peter Hurley6be06e72013-03-06 08:38:21 -050019 * shutdown, either because the tty is being closed or because
20 * the tty is being changed to use a new line discipline
21 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070022 * void (*flush_buffer)(struct tty_struct *tty);
23 *
Peter Hurley6be06e72013-03-06 08:38:21 -050024 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
29 *
Peter Hurley6be06e72013-03-06 08:38:21 -050030 * This function returns the number of input characters the line
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 * discipline may have queued up to be delivered to the user mode
32 * process.
Peter Hurley6be06e72013-03-06 08:38:21 -050033 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 * ssize_t (*read)(struct tty_struct * tty, struct file * file,
35 * unsigned char * buf, size_t nr);
36 *
Peter Hurley6be06e72013-03-06 08:38:21 -050037 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 *
Peter Hurley6be06e72013-03-06 08:38:21 -050042 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 * int (*ioctl)(struct tty_struct * tty, struct file * file,
Peter Hurley6be06e72013-03-06 08:38:21 -050052 * unsigned int cmd, unsigned long arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 *
54 * This function is called when the user requests an ioctl which
Peter Hurley6be06e72013-03-06 08:38:21 -050055 * 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.
Paul Fulghume10cc1d2007-05-10 22:22:50 -070061 *
Peter Hurley6be06e72013-03-06 08:38:21 -050062 * 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
Paul Fulghume10cc1d2007-05-10 22:22:50 -070066 *
Alan Coxedc6afc2006-12-08 02:38:44 -080067 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 *
Peter Hurley6be06e72013-03-06 08:38:21 -050069 * This function notifies the line discpline that a change has
70 * been made to the termios structure.
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 *
Peter Hurley6be06e72013-03-06 08:38:21 -050072 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 *
Linus Torvalds55db4c62011-06-04 06:33:24 +090079 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
Peter Hurley6be06e72013-03-06 08:38:21 -050080 * char *fp, int count);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 *
Peter Hurley6be06e72013-03-06 08:38:21 -050082 * 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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 * void (*write_wakeup)(struct tty_struct *);
90 *
Peter Hurley6be06e72013-03-06 08:38:21 -050091 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 *
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.
Rodolfo Giomettib3e63af2010-03-10 15:23:45 -0800102 *
George Spelvin593fb1ae42013-02-12 02:00:43 -0500103 * void (*dcd_change)(struct tty_struct *tty, unsigned int status)
Rodolfo Giomettib3e63af2010-03-10 15:23:45 -0800104 *
George Spelvin593fb1ae42013-02-12 02:00:43 -0500105 * Tells the discipline that the DCD pin has changed its status.
106 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 */
108
109#include <linux/fs.h>
110#include <linux/wait.h>
Ivo Sieben1541f842012-05-03 14:37:43 +0200111#include <linux/wait.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
Alan Coxa352def2008-07-16 21:53:12 +0100113struct tty_ldisc_ops {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 int magic;
115 char *name;
116 int num;
117 int flags;
Peter Hurley6be06e72013-03-06 08:38:21 -0500118
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 /*
120 * The following routines are called from above.
121 */
122 int (*open)(struct tty_struct *);
123 void (*close)(struct tty_struct *);
124 void (*flush_buffer)(struct tty_struct *tty);
125 ssize_t (*chars_in_buffer)(struct tty_struct *tty);
Peter Hurley6be06e72013-03-06 08:38:21 -0500126 ssize_t (*read)(struct tty_struct *tty, struct file *file,
127 unsigned char __user *buf, size_t nr);
128 ssize_t (*write)(struct tty_struct *tty, struct file *file,
129 const unsigned char *buf, size_t nr);
130 int (*ioctl)(struct tty_struct *tty, struct file *file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 unsigned int cmd, unsigned long arg);
Peter Hurley6be06e72013-03-06 08:38:21 -0500132 long (*compat_ioctl)(struct tty_struct *tty, struct file *file,
Paul Fulghume10cc1d2007-05-10 22:22:50 -0700133 unsigned int cmd, unsigned long arg);
Peter Hurley6be06e72013-03-06 08:38:21 -0500134 void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 unsigned int (*poll)(struct tty_struct *, struct file *,
136 struct poll_table_struct *);
137 int (*hangup)(struct tty_struct *tty);
Peter Hurley6be06e72013-03-06 08:38:21 -0500138
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 /*
140 * The following routines are called from below.
141 */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900142 void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
143 char *fp, int count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 void (*write_wakeup)(struct tty_struct *);
George Spelvin593fb1ae42013-02-12 02:00:43 -0500145 void (*dcd_change)(struct tty_struct *, unsigned int);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
147 struct module *owner;
Peter Hurley6be06e72013-03-06 08:38:21 -0500148
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 int refcount;
150};
151
Alan Coxa352def2008-07-16 21:53:12 +0100152struct tty_ldisc {
153 struct tty_ldisc_ops *ops;
Linus Torvalds18eac1c2009-08-03 10:58:29 -0700154 atomic_t users;
Ivo Sieben1541f842012-05-03 14:37:43 +0200155 wait_queue_head_t wq_idle;
Alan Coxa352def2008-07-16 21:53:12 +0100156};
157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158#define TTY_LDISC_MAGIC 0x5403
159
160#define LDISC_FLAG_DEFINED 0x00000001
161
162#define MODULE_ALIAS_LDISC(ldisc) \
163 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
164
165#endif /* _LINUX_TTY_LDISC_H */