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e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-2.0 |
fff0a2ca NP |
2 | /* |
3 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
4 | */ | |
5 | ||
6 | #include <linux/types.h> | |
7 | #include <linux/kernel.h> | |
8 | #include <linux/termios.h> | |
9 | #include <linux/tty.h> | |
10 | #include <linux/export.h> | |
11 | ||
12 | ||
13 | /* | |
14 | * Routine which returns the baud rate of the tty | |
15 | * | |
16 | * Note that the baud_table needs to be kept in sync with the | |
17 | * include/asm/termbits.h file. | |
18 | */ | |
19 | static const speed_t baud_table[] = { | |
6ada6064 AS |
20 | 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, |
21 | 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, | |
fff0a2ca | 22 | #ifdef __sparc__ |
1ddeb5a7 AS |
23 | 76800, 153600, 307200, 614400, 921600, 500000, 576000, |
24 | 1000000, 1152000, 1500000, 2000000 | |
fff0a2ca NP |
25 | #else |
26 | 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, | |
27 | 2500000, 3000000, 3500000, 4000000 | |
28 | #endif | |
29 | }; | |
30 | ||
fff0a2ca | 31 | static const tcflag_t baud_bits[] = { |
6ada6064 AS |
32 | B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400, |
33 | B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, | |
34 | #ifdef __sparc__ | |
1ddeb5a7 AS |
35 | B76800, B153600, B307200, B614400, B921600, B500000, B576000, |
36 | B1000000, B1152000, B1500000, B2000000 | |
fff0a2ca | 37 | #else |
6ada6064 AS |
38 | B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, |
39 | B2500000, B3000000, B3500000, B4000000 | |
fff0a2ca | 40 | #endif |
6ada6064 | 41 | }; |
fff0a2ca NP |
42 | |
43 | static int n_baud_table = ARRAY_SIZE(baud_table); | |
44 | ||
45 | /** | |
46 | * tty_termios_baud_rate | |
47 | * @termios: termios structure | |
48 | * | |
49 | * Convert termios baud rate data into a speed. This should be called | |
50 | * with the termios lock held if this termios is a terminal termios | |
51 | * structure. May change the termios data. Device drivers can call this | |
52 | * function but should use ->c_[io]speed directly as they are updated. | |
53 | * | |
54 | * Locking: none | |
55 | */ | |
56 | ||
57 | speed_t tty_termios_baud_rate(struct ktermios *termios) | |
58 | { | |
59 | unsigned int cbaud; | |
60 | ||
61 | cbaud = termios->c_cflag & CBAUD; | |
62 | ||
63 | #ifdef BOTHER | |
64 | /* Magic token for arbitrary speed via c_ispeed/c_ospeed */ | |
65 | if (cbaud == BOTHER) | |
66 | return termios->c_ospeed; | |
67 | #endif | |
68 | if (cbaud & CBAUDEX) { | |
69 | cbaud &= ~CBAUDEX; | |
70 | ||
71 | if (cbaud < 1 || cbaud + 15 > n_baud_table) | |
72 | termios->c_cflag &= ~CBAUDEX; | |
73 | else | |
74 | cbaud += 15; | |
75 | } | |
991a2519 | 76 | return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; |
fff0a2ca NP |
77 | } |
78 | EXPORT_SYMBOL(tty_termios_baud_rate); | |
79 | ||
80 | /** | |
81 | * tty_termios_input_baud_rate | |
82 | * @termios: termios structure | |
83 | * | |
84 | * Convert termios baud rate data into a speed. This should be called | |
85 | * with the termios lock held if this termios is a terminal termios | |
86 | * structure. May change the termios data. Device drivers can call this | |
87 | * function but should use ->c_[io]speed directly as they are updated. | |
88 | * | |
89 | * Locking: none | |
90 | */ | |
91 | ||
92 | speed_t tty_termios_input_baud_rate(struct ktermios *termios) | |
93 | { | |
94 | #ifdef IBSHIFT | |
95 | unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD; | |
96 | ||
97 | if (cbaud == B0) | |
98 | return tty_termios_baud_rate(termios); | |
fefe287e | 99 | #ifdef BOTHER |
fff0a2ca NP |
100 | /* Magic token for arbitrary speed via c_ispeed*/ |
101 | if (cbaud == BOTHER) | |
102 | return termios->c_ispeed; | |
fefe287e | 103 | #endif |
fff0a2ca NP |
104 | if (cbaud & CBAUDEX) { |
105 | cbaud &= ~CBAUDEX; | |
106 | ||
107 | if (cbaud < 1 || cbaud + 15 > n_baud_table) | |
108 | termios->c_cflag &= ~(CBAUDEX << IBSHIFT); | |
109 | else | |
110 | cbaud += 15; | |
111 | } | |
991a2519 | 112 | return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; |
fefe287e | 113 | #else /* IBSHIFT */ |
fff0a2ca | 114 | return tty_termios_baud_rate(termios); |
fefe287e | 115 | #endif /* IBSHIFT */ |
fff0a2ca NP |
116 | } |
117 | EXPORT_SYMBOL(tty_termios_input_baud_rate); | |
118 | ||
119 | /** | |
120 | * tty_termios_encode_baud_rate | |
121 | * @termios: ktermios structure holding user requested state | |
fa441954 JS |
122 | * @ibaud: input speed |
123 | * @obaud: output speed | |
fff0a2ca NP |
124 | * |
125 | * Encode the speeds set into the passed termios structure. This is | |
126 | * used as a library helper for drivers so that they can report back | |
127 | * the actual speed selected when it differs from the speed requested | |
128 | * | |
129 | * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour | |
130 | * we need to carefully set the bits when the user does not get the | |
131 | * desired speed. We allow small margins and preserve as much of possible | |
132 | * of the input intent to keep compatibility. | |
133 | * | |
134 | * Locking: Caller should hold termios lock. This is already held | |
135 | * when calling this function from the driver termios handler. | |
136 | * | |
137 | * The ifdefs deal with platforms whose owners have yet to update them | |
138 | * and will all go away once this is done. | |
139 | */ | |
140 | ||
141 | void tty_termios_encode_baud_rate(struct ktermios *termios, | |
142 | speed_t ibaud, speed_t obaud) | |
143 | { | |
144 | int i = 0; | |
145 | int ifound = -1, ofound = -1; | |
146 | int iclose = ibaud/50, oclose = obaud/50; | |
147 | int ibinput = 0; | |
148 | ||
149 | if (obaud == 0) /* CD dropped */ | |
150 | ibaud = 0; /* Clear ibaud to be sure */ | |
151 | ||
152 | termios->c_ispeed = ibaud; | |
153 | termios->c_ospeed = obaud; | |
154 | ||
fefe287e | 155 | #ifdef IBSHIFT |
1cee38f0 JH |
156 | if ((termios->c_cflag >> IBSHIFT) & CBAUD) |
157 | ibinput = 1; /* An input speed was specified */ | |
fefe287e JH |
158 | #endif |
159 | #ifdef BOTHER | |
fff0a2ca NP |
160 | /* If the user asked for a precise weird speed give a precise weird |
161 | answer. If they asked for a Bfoo speed they may have problems | |
162 | digesting non-exact replies so fuzz a bit */ | |
163 | ||
1cee38f0 | 164 | if ((termios->c_cflag & CBAUD) == BOTHER) { |
fff0a2ca | 165 | oclose = 0; |
1cee38f0 JH |
166 | if (!ibinput) |
167 | iclose = 0; | |
168 | } | |
fff0a2ca NP |
169 | if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) |
170 | iclose = 0; | |
fff0a2ca NP |
171 | #endif |
172 | termios->c_cflag &= ~CBAUD; | |
fada18c4 JH |
173 | #ifdef IBSHIFT |
174 | termios->c_cflag &= ~(CBAUD << IBSHIFT); | |
175 | #endif | |
fff0a2ca NP |
176 | |
177 | /* | |
178 | * Our goal is to find a close match to the standard baud rate | |
179 | * returned. Walk the baud rate table and if we get a very close | |
180 | * match then report back the speed as a POSIX Bxxxx value by | |
181 | * preference | |
182 | */ | |
183 | ||
184 | do { | |
185 | if (obaud - oclose <= baud_table[i] && | |
186 | obaud + oclose >= baud_table[i]) { | |
187 | termios->c_cflag |= baud_bits[i]; | |
188 | ofound = i; | |
189 | } | |
190 | if (ibaud - iclose <= baud_table[i] && | |
191 | ibaud + iclose >= baud_table[i]) { | |
192 | /* For the case input == output don't set IBAUD bits | |
193 | if the user didn't do so */ | |
194 | if (ofound == i && !ibinput) | |
195 | ifound = i; | |
196 | #ifdef IBSHIFT | |
197 | else { | |
198 | ifound = i; | |
199 | termios->c_cflag |= (baud_bits[i] << IBSHIFT); | |
200 | } | |
201 | #endif | |
202 | } | |
203 | } while (++i < n_baud_table); | |
204 | ||
205 | /* | |
206 | * If we found no match then use BOTHER if provided or warn | |
207 | * the user their platform maintainer needs to wake up if not. | |
208 | */ | |
209 | #ifdef BOTHER | |
210 | if (ofound == -1) | |
211 | termios->c_cflag |= BOTHER; | |
212 | /* Set exact input bits only if the input and output differ or the | |
213 | user already did */ | |
214 | if (ifound == -1 && (ibaud != obaud || ibinput)) | |
215 | termios->c_cflag |= (BOTHER << IBSHIFT); | |
216 | #else | |
217 | if (ifound == -1 || ofound == -1) | |
218 | pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n"); | |
219 | #endif | |
220 | } | |
221 | EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate); | |
222 | ||
223 | /** | |
224 | * tty_encode_baud_rate - set baud rate of the tty | |
6e30f283 | 225 | * @tty: terminal device |
fff0a2ca | 226 | * @ibaud: input baud rate |
fa441954 | 227 | * @obaud: output baud rate |
fff0a2ca NP |
228 | * |
229 | * Update the current termios data for the tty with the new speed | |
230 | * settings. The caller must hold the termios_rwsem for the tty in | |
231 | * question. | |
232 | */ | |
233 | ||
234 | void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud) | |
235 | { | |
236 | tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud); | |
237 | } | |
238 | EXPORT_SYMBOL_GPL(tty_encode_baud_rate); |