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