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
238
239
240
241
242
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/termios.h>
#include <linux/tty.h>
#include <linux/export.h>
#include "tty.h"
/*
* Routine which returns the baud rate of the tty
*
* Note that the baud_table needs to be kept in sync with the
* include/asm/termbits.h file.
*/
static const speed_t baud_table[] = {
0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
#ifdef __sparc__
76800, 153600, 307200, 614400, 921600, 500000, 576000,
1000000, 1152000, 1500000, 2000000
#else
500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
2500000, 3000000, 3500000, 4000000
#endif
};
static const tcflag_t baud_bits[] = {
B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400,
B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800,
#ifdef __sparc__
B76800, B153600, B307200, B614400, B921600, B500000, B576000,
B1000000, B1152000, B1500000, B2000000
#else
B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000,
B2500000, B3000000, B3500000, B4000000
#endif
};
static int n_baud_table = ARRAY_SIZE(baud_table);
/**
* tty_termios_baud_rate
* @termios: termios structure
*
* Convert termios baud rate data into a speed. This should be called
* with the termios lock held if this termios is a terminal termios
* structure. May change the termios data. Device drivers can call this
* function but should use ->c_[io]speed directly as they are updated.
*
* Locking: none
*/
speed_t tty_termios_baud_rate(struct ktermios *termios)
{
unsigned int cbaud;
cbaud = termios->c_cflag & CBAUD;
#ifdef BOTHER
/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
if (cbaud == BOTHER)
return termios->c_ospeed;
#endif
if (cbaud & CBAUDEX) {
cbaud &= ~CBAUDEX;
if (cbaud < 1 || cbaud + 15 > n_baud_table)
termios->c_cflag &= ~CBAUDEX;
else
cbaud += 15;
}
return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
}
EXPORT_SYMBOL(tty_termios_baud_rate);
/**
* tty_termios_input_baud_rate
* @termios: termios structure
*
* Convert termios baud rate data into a speed. This should be called
* with the termios lock held if this termios is a terminal termios
* structure. May change the termios data. Device drivers can call this
* function but should use ->c_[io]speed directly as they are updated.
*
* Locking: none
*/
speed_t tty_termios_input_baud_rate(struct ktermios *termios)
{
#ifdef IBSHIFT
unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
if (cbaud == B0)
return tty_termios_baud_rate(termios);
#ifdef BOTHER
/* Magic token for arbitrary speed via c_ispeed*/
if (cbaud == BOTHER)
return termios->c_ispeed;
#endif
if (cbaud & CBAUDEX) {
cbaud &= ~CBAUDEX;
if (cbaud < 1 || cbaud + 15 > n_baud_table)
termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
else
cbaud += 15;
}
return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
#else /* IBSHIFT */
return tty_termios_baud_rate(termios);
#endif /* IBSHIFT */
}
EXPORT_SYMBOL(tty_termios_input_baud_rate);
/**
* tty_termios_encode_baud_rate
* @termios: ktermios structure holding user requested state
* @ibaud: input speed
* @obaud: output speed
*
* Encode the speeds set into the passed termios structure. This is
* used as a library helper for drivers so that they can report back
* the actual speed selected when it differs from the speed requested
*
* For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
* we need to carefully set the bits when the user does not get the
* desired speed. We allow small margins and preserve as much of possible
* of the input intent to keep compatibility.
*
* Locking: Caller should hold termios lock. This is already held
* when calling this function from the driver termios handler.
*
* The ifdefs deal with platforms whose owners have yet to update them
* and will all go away once this is done.
*/
void tty_termios_encode_baud_rate(struct ktermios *termios,
speed_t ibaud, speed_t obaud)
{
int i = 0;
int ifound = -1, ofound = -1;
int iclose = ibaud/50, oclose = obaud/50;
int ibinput = 0;
if (obaud == 0) /* CD dropped */
ibaud = 0; /* Clear ibaud to be sure */
termios->c_ispeed = ibaud;
termios->c_ospeed = obaud;
#ifdef IBSHIFT
if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
ibinput = 1; /* An input speed was specified */
#endif
#ifdef BOTHER
/* If the user asked for a precise weird speed give a precise weird
* answer. If they asked for a Bfoo speed they may have problems
* digesting non-exact replies so fuzz a bit.
*/
if ((termios->c_cflag & CBAUD) == BOTHER) {
oclose = 0;
if (!ibinput)
iclose = 0;
}
if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
iclose = 0;
#endif
termios->c_cflag &= ~CBAUD;
#ifdef IBSHIFT
termios->c_cflag &= ~(CBAUD << IBSHIFT);
#endif
/*
* Our goal is to find a close match to the standard baud rate
* returned. Walk the baud rate table and if we get a very close
* match then report back the speed as a POSIX Bxxxx value by
* preference
*/
do {
if (obaud - oclose <= baud_table[i] &&
obaud + oclose >= baud_table[i]) {
termios->c_cflag |= baud_bits[i];
ofound = i;
}
if (ibaud - iclose <= baud_table[i] &&
ibaud + iclose >= baud_table[i]) {
/* For the case input == output don't set IBAUD bits
* if the user didn't do so.
*/
if (ofound == i && !ibinput)
ifound = i;
#ifdef IBSHIFT
else {
ifound = i;
termios->c_cflag |= (baud_bits[i] << IBSHIFT);
}
#endif
}
} while (++i < n_baud_table);
/*
* If we found no match then use BOTHER if provided or warn
* the user their platform maintainer needs to wake up if not.
*/
#ifdef BOTHER
if (ofound == -1)
termios->c_cflag |= BOTHER;
/* Set exact input bits only if the input and output differ or the
* user already did.
*/
if (ifound == -1 && (ibaud != obaud || ibinput))
termios->c_cflag |= (BOTHER << IBSHIFT);
#else
if (ifound == -1 || ofound == -1)
pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n");
#endif
}
EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
/**
* tty_encode_baud_rate - set baud rate of the tty
* @tty: terminal device
* @ibaud: input baud rate
* @obaud: output baud rate
*
* Update the current termios data for the tty with the new speed
* settings. The caller must hold the termios_rwsem for the tty in
* question.
*/
void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
{
tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
}
EXPORT_SYMBOL_GPL(tty_encode_baud_rate);
|
