1 #ifndef _LINUX_TTY_LDISC_H
2 #define _LINUX_TTY_LDISC_H
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.
10 * int (*open)(struct tty_struct *);
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.
16 * void (*close)(struct tty_struct *);
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
22 * void (*flush_buffer)(struct tty_struct *tty);
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.
28 * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
30 * This function returns the number of input characters the line
31 * discipline may have queued up to be delivered to the user mode
34 * ssize_t (*read)(struct tty_struct * tty, struct file * file,
35 * unsigned char * buf, size_t nr);
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.
42 * ssize_t (*write)(struct tty_struct * tty, struct file * file,
43 * const unsigned char * buf, size_t nr);
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.
51 * int (*ioctl)(struct tty_struct * tty, struct file * file,
52 * unsigned int cmd, unsigned long arg);
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.
62 * long (*compat_ioctl)(struct tty_struct * tty, struct file * file,
63 * unsigned int cmd, unsigned long arg);
65 * Process ioctl calls from 32-bit process on 64-bit system
67 * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
69 * This function notifies the line discpline that a change has
70 * been made to the termios structure.
72 * int (*poll)(struct tty_struct * tty, struct file * file,
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.
79 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
80 * char *fp, int count);
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.
89 * void (*write_wakeup)(struct tty_struct *);
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.
96 * int (*hangup)(struct tty_struct *)
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.
103 * void (*dcd_change)(struct tty_struct *tty, unsigned int status,
104 * struct timespec *ts)
106 * Tells the discipline that the DCD pin has changed its status and
107 * the relative timestamp. Pointer ts can be NULL.
110 #include <linux/fs.h>
111 #include <linux/wait.h>
113 struct tty_ldisc_ops {
120 * The following routines are called from above.
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);
126 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,
131 unsigned int cmd, unsigned long arg);
132 long (*compat_ioctl)(struct tty_struct * tty, struct file * file,
133 unsigned int cmd, unsigned long arg);
134 void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
135 unsigned int (*poll)(struct tty_struct *, struct file *,
136 struct poll_table_struct *);
137 int (*hangup)(struct tty_struct *tty);
140 * The following routines are called from below.
142 void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
143 char *fp, int count);
144 void (*write_wakeup)(struct tty_struct *);
145 void (*dcd_change)(struct tty_struct *, unsigned int,
148 struct module *owner;
154 struct tty_ldisc_ops *ops;
158 #define TTY_LDISC_MAGIC 0x5403
160 #define LDISC_FLAG_DEFINED 0x00000001
162 #define MODULE_ALIAS_LDISC(ldisc) \
163 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
165 #endif /* _LINUX_TTY_LDISC_H */