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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[] = { | |
20 | 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, | |
21 | 9600, 19200, 38400, 57600, 115200, 230400, 460800, | |
22 | #ifdef __sparc__ | |
23 | 76800, 153600, 307200, 614400, 921600 | |
24 | #else | |
25 | 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, | |
26 | 2500000, 3000000, 3500000, 4000000 | |
27 | #endif | |
28 | }; | |
29 | ||
30 | #ifndef __sparc__ | |
31 | static const tcflag_t baud_bits[] = { | |
32 | B0, B50, B75, B110, B134, B150, B200, B300, B600, | |
33 | B1200, B1800, B2400, B4800, B9600, B19200, B38400, | |
34 | B57600, B115200, B230400, B460800, B500000, B576000, | |
35 | B921600, B1000000, B1152000, B1500000, B2000000, B2500000, | |
36 | B3000000, B3500000, B4000000 | |
37 | }; | |
38 | #else | |
39 | static const tcflag_t baud_bits[] = { | |
40 | B0, B50, B75, B110, B134, B150, B200, B300, B600, | |
41 | B1200, B1800, B2400, B4800, B9600, B19200, B38400, | |
42 | B57600, B115200, B230400, B460800, B76800, B153600, | |
43 | B307200, B614400, B921600 | |
44 | }; | |
45 | #endif | |
46 | ||
47 | static int n_baud_table = ARRAY_SIZE(baud_table); | |
48 | ||
49 | /** | |
50 | * tty_termios_baud_rate | |
51 | * @termios: termios structure | |
52 | * | |
53 | * Convert termios baud rate data into a speed. This should be called | |
54 | * with the termios lock held if this termios is a terminal termios | |
55 | * structure. May change the termios data. Device drivers can call this | |
56 | * function but should use ->c_[io]speed directly as they are updated. | |
57 | * | |
58 | * Locking: none | |
59 | */ | |
60 | ||
61 | speed_t tty_termios_baud_rate(struct ktermios *termios) | |
62 | { | |
63 | unsigned int cbaud; | |
64 | ||
65 | cbaud = termios->c_cflag & CBAUD; | |
66 | ||
67 | #ifdef BOTHER | |
68 | /* Magic token for arbitrary speed via c_ispeed/c_ospeed */ | |
69 | if (cbaud == BOTHER) | |
70 | return termios->c_ospeed; | |
71 | #endif | |
72 | if (cbaud & CBAUDEX) { | |
73 | cbaud &= ~CBAUDEX; | |
74 | ||
75 | if (cbaud < 1 || cbaud + 15 > n_baud_table) | |
76 | termios->c_cflag &= ~CBAUDEX; | |
77 | else | |
78 | cbaud += 15; | |
79 | } | |
991a2519 | 80 | return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; |
fff0a2ca NP |
81 | } |
82 | EXPORT_SYMBOL(tty_termios_baud_rate); | |
83 | ||
84 | /** | |
85 | * tty_termios_input_baud_rate | |
86 | * @termios: termios structure | |
87 | * | |
88 | * Convert termios baud rate data into a speed. This should be called | |
89 | * with the termios lock held if this termios is a terminal termios | |
90 | * structure. May change the termios data. Device drivers can call this | |
91 | * function but should use ->c_[io]speed directly as they are updated. | |
92 | * | |
93 | * Locking: none | |
94 | */ | |
95 | ||
96 | speed_t tty_termios_input_baud_rate(struct ktermios *termios) | |
97 | { | |
98 | #ifdef IBSHIFT | |
99 | unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD; | |
100 | ||
101 | if (cbaud == B0) | |
102 | return tty_termios_baud_rate(termios); | |
fefe287e | 103 | #ifdef BOTHER |
fff0a2ca NP |
104 | /* Magic token for arbitrary speed via c_ispeed*/ |
105 | if (cbaud == BOTHER) | |
106 | return termios->c_ispeed; | |
fefe287e | 107 | #endif |
fff0a2ca NP |
108 | if (cbaud & CBAUDEX) { |
109 | cbaud &= ~CBAUDEX; | |
110 | ||
111 | if (cbaud < 1 || cbaud + 15 > n_baud_table) | |
112 | termios->c_cflag &= ~(CBAUDEX << IBSHIFT); | |
113 | else | |
114 | cbaud += 15; | |
115 | } | |
991a2519 | 116 | return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; |
fefe287e | 117 | #else /* IBSHIFT */ |
fff0a2ca | 118 | return tty_termios_baud_rate(termios); |
fefe287e | 119 | #endif /* IBSHIFT */ |
fff0a2ca NP |
120 | } |
121 | EXPORT_SYMBOL(tty_termios_input_baud_rate); | |
122 | ||
123 | /** | |
124 | * tty_termios_encode_baud_rate | |
125 | * @termios: ktermios structure holding user requested state | |
126 | * @ispeed: input speed | |
127 | * @ospeed: output speed | |
128 | * | |
129 | * Encode the speeds set into the passed termios structure. This is | |
130 | * used as a library helper for drivers so that they can report back | |
131 | * the actual speed selected when it differs from the speed requested | |
132 | * | |
133 | * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour | |
134 | * we need to carefully set the bits when the user does not get the | |
135 | * desired speed. We allow small margins and preserve as much of possible | |
136 | * of the input intent to keep compatibility. | |
137 | * | |
138 | * Locking: Caller should hold termios lock. This is already held | |
139 | * when calling this function from the driver termios handler. | |
140 | * | |
141 | * The ifdefs deal with platforms whose owners have yet to update them | |
142 | * and will all go away once this is done. | |
143 | */ | |
144 | ||
145 | void tty_termios_encode_baud_rate(struct ktermios *termios, | |
146 | speed_t ibaud, speed_t obaud) | |
147 | { | |
148 | int i = 0; | |
149 | int ifound = -1, ofound = -1; | |
150 | int iclose = ibaud/50, oclose = obaud/50; | |
151 | int ibinput = 0; | |
152 | ||
153 | if (obaud == 0) /* CD dropped */ | |
154 | ibaud = 0; /* Clear ibaud to be sure */ | |
155 | ||
156 | termios->c_ispeed = ibaud; | |
157 | termios->c_ospeed = obaud; | |
158 | ||
fefe287e | 159 | #ifdef IBSHIFT |
1cee38f0 JH |
160 | if ((termios->c_cflag >> IBSHIFT) & CBAUD) |
161 | ibinput = 1; /* An input speed was specified */ | |
fefe287e JH |
162 | #endif |
163 | #ifdef BOTHER | |
fff0a2ca NP |
164 | /* If the user asked for a precise weird speed give a precise weird |
165 | answer. If they asked for a Bfoo speed they may have problems | |
166 | digesting non-exact replies so fuzz a bit */ | |
167 | ||
1cee38f0 | 168 | if ((termios->c_cflag & CBAUD) == BOTHER) { |
fff0a2ca | 169 | oclose = 0; |
1cee38f0 JH |
170 | if (!ibinput) |
171 | iclose = 0; | |
172 | } | |
fff0a2ca NP |
173 | if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) |
174 | iclose = 0; | |
fff0a2ca NP |
175 | #endif |
176 | termios->c_cflag &= ~CBAUD; | |
fada18c4 JH |
177 | #ifdef IBSHIFT |
178 | termios->c_cflag &= ~(CBAUD << IBSHIFT); | |
179 | #endif | |
fff0a2ca NP |
180 | |
181 | /* | |
182 | * Our goal is to find a close match to the standard baud rate | |
183 | * returned. Walk the baud rate table and if we get a very close | |
184 | * match then report back the speed as a POSIX Bxxxx value by | |
185 | * preference | |
186 | */ | |
187 | ||
188 | do { | |
189 | if (obaud - oclose <= baud_table[i] && | |
190 | obaud + oclose >= baud_table[i]) { | |
191 | termios->c_cflag |= baud_bits[i]; | |
192 | ofound = i; | |
193 | } | |
194 | if (ibaud - iclose <= baud_table[i] && | |
195 | ibaud + iclose >= baud_table[i]) { | |
196 | /* For the case input == output don't set IBAUD bits | |
197 | if the user didn't do so */ | |
198 | if (ofound == i && !ibinput) | |
199 | ifound = i; | |
200 | #ifdef IBSHIFT | |
201 | else { | |
202 | ifound = i; | |
203 | termios->c_cflag |= (baud_bits[i] << IBSHIFT); | |
204 | } | |
205 | #endif | |
206 | } | |
207 | } while (++i < n_baud_table); | |
208 | ||
209 | /* | |
210 | * If we found no match then use BOTHER if provided or warn | |
211 | * the user their platform maintainer needs to wake up if not. | |
212 | */ | |
213 | #ifdef BOTHER | |
214 | if (ofound == -1) | |
215 | termios->c_cflag |= BOTHER; | |
216 | /* Set exact input bits only if the input and output differ or the | |
217 | user already did */ | |
218 | if (ifound == -1 && (ibaud != obaud || ibinput)) | |
219 | termios->c_cflag |= (BOTHER << IBSHIFT); | |
220 | #else | |
221 | if (ifound == -1 || ofound == -1) | |
222 | pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n"); | |
223 | #endif | |
224 | } | |
225 | EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate); | |
226 | ||
227 | /** | |
228 | * tty_encode_baud_rate - set baud rate of the tty | |
229 | * @ibaud: input baud rate | |
230 | * @obad: output baud rate | |
231 | * | |
232 | * Update the current termios data for the tty with the new speed | |
233 | * settings. The caller must hold the termios_rwsem for the tty in | |
234 | * question. | |
235 | */ | |
236 | ||
237 | void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud) | |
238 | { | |
239 | tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud); | |
240 | } | |
241 | EXPORT_SYMBOL_GPL(tty_encode_baud_rate); |