1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_TTY_LDISC_H
#define _LINUX_TTY_LDISC_H
struct tty_struct;
/*
* This structure defines the interface between the tty line discipline
* implementation and the tty routines. The following routines can be
* defined; unless noted otherwise, they are optional, and can be
* filled in with a null pointer.
*
* int (*open)(struct tty_struct *);
*
* This function is called when the line discipline is associated
* with the tty. The line discipline can use this as an
* opportunity to initialize any state needed by the ldisc routines.
*
* void (*close)(struct tty_struct *);
*
* This function is called when the line discipline is being
* shutdown, either because the tty is being closed or because
* the tty is being changed to use a new line discipline
*
* void (*flush_buffer)(struct tty_struct *tty);
*
* This function instructs the line discipline to clear its
* buffers of any input characters it may have queued to be
* delivered to the user mode process.
*
* ssize_t (*read)(struct tty_struct * tty, struct file * file,
* unsigned char * buf, size_t nr);
*
* This function is called when the user requests to read from
* the tty. The line discipline will return whatever characters
* it has buffered up for the user. If this function is not
* defined, the user will receive an EIO error.
*
* ssize_t (*write)(struct tty_struct * tty, struct file * file,
* const unsigned char * buf, size_t nr);
*
* This function is called when the user requests to write to the
* tty. The line discipline will deliver the characters to the
* low-level tty device for transmission, optionally performing
* some processing on the characters first. If this function is
* not defined, the user will receive an EIO error.
*
* int (*ioctl)(struct tty_struct * tty, struct file * file,
* unsigned int cmd, unsigned long arg);
*
* This function is called when the user requests an ioctl which
* is not handled by the tty layer or the low-level tty driver.
* It is intended for ioctls which affect line discpline
* operation. Note that the search order for ioctls is (1) tty
* layer, (2) tty low-level driver, (3) line discpline. So a
* low-level driver can "grab" an ioctl request before the line
* discpline has a chance to see it.
*
* int (*compat_ioctl)(struct tty_struct * tty, struct file * file,
* unsigned int cmd, unsigned long arg);
*
* Process ioctl calls from 32-bit process on 64-bit system
*
* NOTE: only ioctls that are neither "pointer to compatible
* structure" nor tty-generic. Something private that takes
* an integer or a pointer to wordsize-sensitive structure
* belongs here, but most of ldiscs will happily leave
* it NULL.
*
* void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
*
* This function notifies the line discpline that a change has
* been made to the termios structure.
*
* int (*poll)(struct tty_struct * tty, struct file * file,
* poll_table *wait);
*
* This function is called when a user attempts to select/poll on a
* tty device. It is solely the responsibility of the line
* discipline to handle poll requests.
*
* void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
* char *fp, int count);
*
* This function is called by the low-level tty driver to send
* characters received by the hardware to the line discpline for
* processing. <cp> is a pointer to the buffer of input
* character received by the device. <fp> is a pointer to a
* pointer of flag bytes which indicate whether a character was
* received with a parity error, etc. <fp> may be NULL to indicate
* all data received is TTY_NORMAL.
*
* void (*write_wakeup)(struct tty_struct *);
*
* This function is called by the low-level tty driver to signal
* that line discpline should try to send more characters to the
* low-level driver for transmission. If the line discpline does
* not have any more data to send, it can just return. If the line
* discipline does have some data to send, please arise a tasklet
* or workqueue to do the real data transfer. Do not send data in
* this hook, it may leads to a deadlock.
*
* int (*hangup)(struct tty_struct *)
*
* Called on a hangup. Tells the discipline that it should
* cease I/O to the tty driver. Can sleep. The driver should
* seek to perform this action quickly but should wait until
* any pending driver I/O is completed.
*
* void (*dcd_change)(struct tty_struct *tty, unsigned int status)
*
* Tells the discipline that the DCD pin has changed its status.
* Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
*
* int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
* char *fp, int count);
*
* This function is called by the low-level tty driver to send
* characters received by the hardware to the line discpline for
* processing. <cp> is a pointer to the buffer of input
* character received by the device. <fp> is a pointer to a
* pointer of flag bytes which indicate whether a character was
* received with a parity error, etc. <fp> may be NULL to indicate
* all data received is TTY_NORMAL.
* If assigned, prefer this function for automatic flow control.
*/
#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/atomic.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/seq_file.h>
/*
* the semaphore definition
*/
struct ld_semaphore {
atomic_long_t count;
raw_spinlock_t wait_lock;
unsigned int wait_readers;
struct list_head read_wait;
struct list_head write_wait;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
};
void __init_ldsem(struct ld_semaphore *sem, const char *name,
struct lock_class_key *key);
#define init_ldsem(sem) \
do { \
static struct lock_class_key __key; \
\
__init_ldsem((sem), #sem, &__key); \
} while (0)
int ldsem_down_read(struct ld_semaphore *sem, long timeout);
int ldsem_down_read_trylock(struct ld_semaphore *sem);
int ldsem_down_write(struct ld_semaphore *sem, long timeout);
int ldsem_down_write_trylock(struct ld_semaphore *sem);
void ldsem_up_read(struct ld_semaphore *sem);
void ldsem_up_write(struct ld_semaphore *sem);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
long timeout);
int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
long timeout);
#else
# define ldsem_down_read_nested(sem, subclass, timeout) \
ldsem_down_read(sem, timeout)
# define ldsem_down_write_nested(sem, subclass, timeout) \
ldsem_down_write(sem, timeout)
#endif
struct tty_ldisc_ops {
char *name;
int num;
/*
* The following routines are called from above.
*/
int (*open)(struct tty_struct *);
void (*close)(struct tty_struct *);
void (*flush_buffer)(struct tty_struct *tty);
ssize_t (*read)(struct tty_struct *tty, struct file *file,
unsigned char *buf, size_t nr,
void **cookie, unsigned long offset);
ssize_t (*write)(struct tty_struct *tty, struct file *file,
const unsigned char *buf, size_t nr);
int (*ioctl)(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg);
int (*compat_ioctl)(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg);
void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
__poll_t (*poll)(struct tty_struct *, struct file *,
struct poll_table_struct *);
void (*hangup)(struct tty_struct *tty);
/*
* The following routines are called from below.
*/
void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
const char *fp, int count);
void (*write_wakeup)(struct tty_struct *);
void (*dcd_change)(struct tty_struct *, unsigned int);
int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
const char *fp, int count);
struct module *owner;
};
struct tty_ldisc {
struct tty_ldisc_ops *ops;
struct tty_struct *tty;
};
#define MODULE_ALIAS_LDISC(ldisc) \
MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
extern const struct seq_operations tty_ldiscs_seq_ops;
struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
void tty_ldisc_deref(struct tty_ldisc *);
struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
void tty_ldisc_flush(struct tty_struct *tty);
int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc);
void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc);
int tty_set_ldisc(struct tty_struct *tty, int disc);
#endif /* _LINUX_TTY_LDISC_H */
|
