1e3b3d0f5SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2fff0a2caSNicolas Pitre /* 3fff0a2caSNicolas Pitre * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 4fff0a2caSNicolas Pitre */ 5fff0a2caSNicolas Pitre 6fff0a2caSNicolas Pitre #include <linux/types.h> 7fff0a2caSNicolas Pitre #include <linux/kernel.h> 8fff0a2caSNicolas Pitre #include <linux/termios.h> 9fff0a2caSNicolas Pitre #include <linux/tty.h> 10fff0a2caSNicolas Pitre #include <linux/export.h> 11*5ffa6e34SGreg Kroah-Hartman #include "tty.h" 12fff0a2caSNicolas Pitre 13fff0a2caSNicolas Pitre 14fff0a2caSNicolas Pitre /* 15fff0a2caSNicolas Pitre * Routine which returns the baud rate of the tty 16fff0a2caSNicolas Pitre * 17fff0a2caSNicolas Pitre * Note that the baud_table needs to be kept in sync with the 18fff0a2caSNicolas Pitre * include/asm/termbits.h file. 19fff0a2caSNicolas Pitre */ 20fff0a2caSNicolas Pitre static const speed_t baud_table[] = { 216ada6064SAndy Shevchenko 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 226ada6064SAndy Shevchenko 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 23fff0a2caSNicolas Pitre #ifdef __sparc__ 241ddeb5a7SAndy Shevchenko 76800, 153600, 307200, 614400, 921600, 500000, 576000, 251ddeb5a7SAndy Shevchenko 1000000, 1152000, 1500000, 2000000 26fff0a2caSNicolas Pitre #else 27fff0a2caSNicolas Pitre 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, 28fff0a2caSNicolas Pitre 2500000, 3000000, 3500000, 4000000 29fff0a2caSNicolas Pitre #endif 30fff0a2caSNicolas Pitre }; 31fff0a2caSNicolas Pitre 32fff0a2caSNicolas Pitre static const tcflag_t baud_bits[] = { 336ada6064SAndy Shevchenko B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400, 346ada6064SAndy Shevchenko B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, 356ada6064SAndy Shevchenko #ifdef __sparc__ 361ddeb5a7SAndy Shevchenko B76800, B153600, B307200, B614400, B921600, B500000, B576000, 371ddeb5a7SAndy Shevchenko B1000000, B1152000, B1500000, B2000000 38fff0a2caSNicolas Pitre #else 396ada6064SAndy Shevchenko B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, 406ada6064SAndy Shevchenko B2500000, B3000000, B3500000, B4000000 41fff0a2caSNicolas Pitre #endif 426ada6064SAndy Shevchenko }; 43fff0a2caSNicolas Pitre 44fff0a2caSNicolas Pitre static int n_baud_table = ARRAY_SIZE(baud_table); 45fff0a2caSNicolas Pitre 46fff0a2caSNicolas Pitre /** 47fff0a2caSNicolas Pitre * tty_termios_baud_rate 48fff0a2caSNicolas Pitre * @termios: termios structure 49fff0a2caSNicolas Pitre * 50fff0a2caSNicolas Pitre * Convert termios baud rate data into a speed. This should be called 51fff0a2caSNicolas Pitre * with the termios lock held if this termios is a terminal termios 52fff0a2caSNicolas Pitre * structure. May change the termios data. Device drivers can call this 53fff0a2caSNicolas Pitre * function but should use ->c_[io]speed directly as they are updated. 54fff0a2caSNicolas Pitre * 55fff0a2caSNicolas Pitre * Locking: none 56fff0a2caSNicolas Pitre */ 57fff0a2caSNicolas Pitre 58fff0a2caSNicolas Pitre speed_t tty_termios_baud_rate(struct ktermios *termios) 59fff0a2caSNicolas Pitre { 60fff0a2caSNicolas Pitre unsigned int cbaud; 61fff0a2caSNicolas Pitre 62fff0a2caSNicolas Pitre cbaud = termios->c_cflag & CBAUD; 63fff0a2caSNicolas Pitre 64fff0a2caSNicolas Pitre #ifdef BOTHER 65fff0a2caSNicolas Pitre /* Magic token for arbitrary speed via c_ispeed/c_ospeed */ 66fff0a2caSNicolas Pitre if (cbaud == BOTHER) 67fff0a2caSNicolas Pitre return termios->c_ospeed; 68fff0a2caSNicolas Pitre #endif 69fff0a2caSNicolas Pitre if (cbaud & CBAUDEX) { 70fff0a2caSNicolas Pitre cbaud &= ~CBAUDEX; 71fff0a2caSNicolas Pitre 72fff0a2caSNicolas Pitre if (cbaud < 1 || cbaud + 15 > n_baud_table) 73fff0a2caSNicolas Pitre termios->c_cflag &= ~CBAUDEX; 74fff0a2caSNicolas Pitre else 75fff0a2caSNicolas Pitre cbaud += 15; 76fff0a2caSNicolas Pitre } 77991a2519SH. Peter Anvin return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; 78fff0a2caSNicolas Pitre } 79fff0a2caSNicolas Pitre EXPORT_SYMBOL(tty_termios_baud_rate); 80fff0a2caSNicolas Pitre 81fff0a2caSNicolas Pitre /** 82fff0a2caSNicolas Pitre * tty_termios_input_baud_rate 83fff0a2caSNicolas Pitre * @termios: termios structure 84fff0a2caSNicolas Pitre * 85fff0a2caSNicolas Pitre * Convert termios baud rate data into a speed. This should be called 86fff0a2caSNicolas Pitre * with the termios lock held if this termios is a terminal termios 87fff0a2caSNicolas Pitre * structure. May change the termios data. Device drivers can call this 88fff0a2caSNicolas Pitre * function but should use ->c_[io]speed directly as they are updated. 89fff0a2caSNicolas Pitre * 90fff0a2caSNicolas Pitre * Locking: none 91fff0a2caSNicolas Pitre */ 92fff0a2caSNicolas Pitre 93fff0a2caSNicolas Pitre speed_t tty_termios_input_baud_rate(struct ktermios *termios) 94fff0a2caSNicolas Pitre { 95fff0a2caSNicolas Pitre #ifdef IBSHIFT 96fff0a2caSNicolas Pitre unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD; 97fff0a2caSNicolas Pitre 98fff0a2caSNicolas Pitre if (cbaud == B0) 99fff0a2caSNicolas Pitre return tty_termios_baud_rate(termios); 100fefe287eSJohan Hovold #ifdef BOTHER 101fff0a2caSNicolas Pitre /* Magic token for arbitrary speed via c_ispeed*/ 102fff0a2caSNicolas Pitre if (cbaud == BOTHER) 103fff0a2caSNicolas Pitre return termios->c_ispeed; 104fefe287eSJohan Hovold #endif 105fff0a2caSNicolas Pitre if (cbaud & CBAUDEX) { 106fff0a2caSNicolas Pitre cbaud &= ~CBAUDEX; 107fff0a2caSNicolas Pitre 108fff0a2caSNicolas Pitre if (cbaud < 1 || cbaud + 15 > n_baud_table) 109fff0a2caSNicolas Pitre termios->c_cflag &= ~(CBAUDEX << IBSHIFT); 110fff0a2caSNicolas Pitre else 111fff0a2caSNicolas Pitre cbaud += 15; 112fff0a2caSNicolas Pitre } 113991a2519SH. Peter Anvin return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; 114fefe287eSJohan Hovold #else /* IBSHIFT */ 115fff0a2caSNicolas Pitre return tty_termios_baud_rate(termios); 116fefe287eSJohan Hovold #endif /* IBSHIFT */ 117fff0a2caSNicolas Pitre } 118fff0a2caSNicolas Pitre EXPORT_SYMBOL(tty_termios_input_baud_rate); 119fff0a2caSNicolas Pitre 120fff0a2caSNicolas Pitre /** 121fff0a2caSNicolas Pitre * tty_termios_encode_baud_rate 122fff0a2caSNicolas Pitre * @termios: ktermios structure holding user requested state 123fa441954SJiri Slaby * @ibaud: input speed 124fa441954SJiri Slaby * @obaud: output speed 125fff0a2caSNicolas Pitre * 126fff0a2caSNicolas Pitre * Encode the speeds set into the passed termios structure. This is 127fff0a2caSNicolas Pitre * used as a library helper for drivers so that they can report back 128fff0a2caSNicolas Pitre * the actual speed selected when it differs from the speed requested 129fff0a2caSNicolas Pitre * 130fff0a2caSNicolas Pitre * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour 131fff0a2caSNicolas Pitre * we need to carefully set the bits when the user does not get the 132fff0a2caSNicolas Pitre * desired speed. We allow small margins and preserve as much of possible 133fff0a2caSNicolas Pitre * of the input intent to keep compatibility. 134fff0a2caSNicolas Pitre * 135fff0a2caSNicolas Pitre * Locking: Caller should hold termios lock. This is already held 136fff0a2caSNicolas Pitre * when calling this function from the driver termios handler. 137fff0a2caSNicolas Pitre * 138fff0a2caSNicolas Pitre * The ifdefs deal with platforms whose owners have yet to update them 139fff0a2caSNicolas Pitre * and will all go away once this is done. 140fff0a2caSNicolas Pitre */ 141fff0a2caSNicolas Pitre 142fff0a2caSNicolas Pitre void tty_termios_encode_baud_rate(struct ktermios *termios, 143fff0a2caSNicolas Pitre speed_t ibaud, speed_t obaud) 144fff0a2caSNicolas Pitre { 145fff0a2caSNicolas Pitre int i = 0; 146fff0a2caSNicolas Pitre int ifound = -1, ofound = -1; 147fff0a2caSNicolas Pitre int iclose = ibaud/50, oclose = obaud/50; 148fff0a2caSNicolas Pitre int ibinput = 0; 149fff0a2caSNicolas Pitre 150fff0a2caSNicolas Pitre if (obaud == 0) /* CD dropped */ 151fff0a2caSNicolas Pitre ibaud = 0; /* Clear ibaud to be sure */ 152fff0a2caSNicolas Pitre 153fff0a2caSNicolas Pitre termios->c_ispeed = ibaud; 154fff0a2caSNicolas Pitre termios->c_ospeed = obaud; 155fff0a2caSNicolas Pitre 156fefe287eSJohan Hovold #ifdef IBSHIFT 1571cee38f0SJohan Hovold if ((termios->c_cflag >> IBSHIFT) & CBAUD) 1581cee38f0SJohan Hovold ibinput = 1; /* An input speed was specified */ 159fefe287eSJohan Hovold #endif 160fefe287eSJohan Hovold #ifdef BOTHER 161fff0a2caSNicolas Pitre /* If the user asked for a precise weird speed give a precise weird 162fff0a2caSNicolas Pitre answer. If they asked for a Bfoo speed they may have problems 163fff0a2caSNicolas Pitre digesting non-exact replies so fuzz a bit */ 164fff0a2caSNicolas Pitre 1651cee38f0SJohan Hovold if ((termios->c_cflag & CBAUD) == BOTHER) { 166fff0a2caSNicolas Pitre oclose = 0; 1671cee38f0SJohan Hovold if (!ibinput) 1681cee38f0SJohan Hovold iclose = 0; 1691cee38f0SJohan Hovold } 170fff0a2caSNicolas Pitre if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) 171fff0a2caSNicolas Pitre iclose = 0; 172fff0a2caSNicolas Pitre #endif 173fff0a2caSNicolas Pitre termios->c_cflag &= ~CBAUD; 174fada18c4SJohan Hovold #ifdef IBSHIFT 175fada18c4SJohan Hovold termios->c_cflag &= ~(CBAUD << IBSHIFT); 176fada18c4SJohan Hovold #endif 177fff0a2caSNicolas Pitre 178fff0a2caSNicolas Pitre /* 179fff0a2caSNicolas Pitre * Our goal is to find a close match to the standard baud rate 180fff0a2caSNicolas Pitre * returned. Walk the baud rate table and if we get a very close 181fff0a2caSNicolas Pitre * match then report back the speed as a POSIX Bxxxx value by 182fff0a2caSNicolas Pitre * preference 183fff0a2caSNicolas Pitre */ 184fff0a2caSNicolas Pitre 185fff0a2caSNicolas Pitre do { 186fff0a2caSNicolas Pitre if (obaud - oclose <= baud_table[i] && 187fff0a2caSNicolas Pitre obaud + oclose >= baud_table[i]) { 188fff0a2caSNicolas Pitre termios->c_cflag |= baud_bits[i]; 189fff0a2caSNicolas Pitre ofound = i; 190fff0a2caSNicolas Pitre } 191fff0a2caSNicolas Pitre if (ibaud - iclose <= baud_table[i] && 192fff0a2caSNicolas Pitre ibaud + iclose >= baud_table[i]) { 193fff0a2caSNicolas Pitre /* For the case input == output don't set IBAUD bits 194fff0a2caSNicolas Pitre if the user didn't do so */ 195fff0a2caSNicolas Pitre if (ofound == i && !ibinput) 196fff0a2caSNicolas Pitre ifound = i; 197fff0a2caSNicolas Pitre #ifdef IBSHIFT 198fff0a2caSNicolas Pitre else { 199fff0a2caSNicolas Pitre ifound = i; 200fff0a2caSNicolas Pitre termios->c_cflag |= (baud_bits[i] << IBSHIFT); 201fff0a2caSNicolas Pitre } 202fff0a2caSNicolas Pitre #endif 203fff0a2caSNicolas Pitre } 204fff0a2caSNicolas Pitre } while (++i < n_baud_table); 205fff0a2caSNicolas Pitre 206fff0a2caSNicolas Pitre /* 207fff0a2caSNicolas Pitre * If we found no match then use BOTHER if provided or warn 208fff0a2caSNicolas Pitre * the user their platform maintainer needs to wake up if not. 209fff0a2caSNicolas Pitre */ 210fff0a2caSNicolas Pitre #ifdef BOTHER 211fff0a2caSNicolas Pitre if (ofound == -1) 212fff0a2caSNicolas Pitre termios->c_cflag |= BOTHER; 213fff0a2caSNicolas Pitre /* Set exact input bits only if the input and output differ or the 214fff0a2caSNicolas Pitre user already did */ 215fff0a2caSNicolas Pitre if (ifound == -1 && (ibaud != obaud || ibinput)) 216fff0a2caSNicolas Pitre termios->c_cflag |= (BOTHER << IBSHIFT); 217fff0a2caSNicolas Pitre #else 218fff0a2caSNicolas Pitre if (ifound == -1 || ofound == -1) 219fff0a2caSNicolas Pitre pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n"); 220fff0a2caSNicolas Pitre #endif 221fff0a2caSNicolas Pitre } 222fff0a2caSNicolas Pitre EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate); 223fff0a2caSNicolas Pitre 224fff0a2caSNicolas Pitre /** 225fff0a2caSNicolas Pitre * tty_encode_baud_rate - set baud rate of the tty 2266e30f283SLee Jones * @tty: terminal device 227fff0a2caSNicolas Pitre * @ibaud: input baud rate 228fa441954SJiri Slaby * @obaud: output baud rate 229fff0a2caSNicolas Pitre * 230fff0a2caSNicolas Pitre * Update the current termios data for the tty with the new speed 231fff0a2caSNicolas Pitre * settings. The caller must hold the termios_rwsem for the tty in 232fff0a2caSNicolas Pitre * question. 233fff0a2caSNicolas Pitre */ 234fff0a2caSNicolas Pitre 235fff0a2caSNicolas Pitre void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud) 236fff0a2caSNicolas Pitre { 237fff0a2caSNicolas Pitre tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud); 238fff0a2caSNicolas Pitre } 239fff0a2caSNicolas Pitre EXPORT_SYMBOL_GPL(tty_encode_baud_rate); 240