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); 233