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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 * 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 * void (*fasync)(struct tty_struct *, int on)
104 *
105 * Notify line discipline when signal-driven I/O is enabled or
106 * disabled.
107 *
108 * void (*dcd_change)(struct tty_struct *tty, unsigned int status)
109 *
110 * Tells the discipline that the DCD pin has changed its status.
111 * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
112 */
113
114#include <linux/fs.h>
115#include <linux/wait.h>
116#include <linux/wait.h>
117
118
119/*
120 * the semaphore definition
121 */
122struct ld_semaphore {
123 long count;
124 raw_spinlock_t wait_lock;
125 unsigned int wait_readers;
126 struct list_head read_wait;
127 struct list_head write_wait;
128#ifdef CONFIG_DEBUG_LOCK_ALLOC
129 struct lockdep_map dep_map;
130#endif
131};
132
133extern void __init_ldsem(struct ld_semaphore *sem, const char *name,
134 struct lock_class_key *key);
135
136#define init_ldsem(sem) \
137do { \
138 static struct lock_class_key __key; \
139 \
140 __init_ldsem((sem), #sem, &__key); \
141} while (0)
142
143
144extern int ldsem_down_read(struct ld_semaphore *sem, long timeout);
145extern int ldsem_down_read_trylock(struct ld_semaphore *sem);
146extern int ldsem_down_write(struct ld_semaphore *sem, long timeout);
147extern int ldsem_down_write_trylock(struct ld_semaphore *sem);
148extern void ldsem_up_read(struct ld_semaphore *sem);
149extern void ldsem_up_write(struct ld_semaphore *sem);
150
151#ifdef CONFIG_DEBUG_LOCK_ALLOC
152extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
153 long timeout);
154extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
155 long timeout);
156#else
157# define ldsem_down_read_nested(sem, subclass, timeout) \
158 ldsem_down_read(sem, timeout)
159# define ldsem_down_write_nested(sem, subclass, timeout) \
160 ldsem_down_write(sem, timeout)
161#endif
162
163
164struct tty_ldisc_ops {
165 int magic;
166 char *name;
167 int num;
168 int flags;
169
170 /*
171 * The following routines are called from above.
172 */
173 int (*open)(struct tty_struct *);
174 void (*close)(struct tty_struct *);
175 void (*flush_buffer)(struct tty_struct *tty);
176 ssize_t (*chars_in_buffer)(struct tty_struct *tty);
177 ssize_t (*read)(struct tty_struct *tty, struct file *file,
178 unsigned char __user *buf, size_t nr);
179 ssize_t (*write)(struct tty_struct *tty, struct file *file,
180 const unsigned char *buf, size_t nr);
181 int (*ioctl)(struct tty_struct *tty, struct file *file,
182 unsigned int cmd, unsigned long arg);
183 long (*compat_ioctl)(struct tty_struct *tty, struct file *file,
184 unsigned int cmd, unsigned long arg);
185 void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
186 unsigned int (*poll)(struct tty_struct *, struct file *,
187 struct poll_table_struct *);
188 int (*hangup)(struct tty_struct *tty);
189
190 /*
191 * The following routines are called from below.
192 */
193 void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
194 char *fp, int count);
195 void (*write_wakeup)(struct tty_struct *);
196 void (*dcd_change)(struct tty_struct *, unsigned int);
197 void (*fasync)(struct tty_struct *tty, int on);
198
199 struct module *owner;
200
201 int refcount;
202};
203
204struct tty_ldisc {
205 struct tty_ldisc_ops *ops;
206 atomic_t users;
207 wait_queue_head_t wq_idle;
208};
209
210#define TTY_LDISC_MAGIC 0x5403
211
212#define LDISC_FLAG_DEFINED 0x00000001
213
214#define MODULE_ALIAS_LDISC(ldisc) \
215 MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
216
217#endif /* _LINUX_TTY_LDISC_H */