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> 11fff0a2caSNicolas Pitre 12fff0a2caSNicolas Pitre 13fff0a2caSNicolas Pitre /* 14fff0a2caSNicolas Pitre * Routine which returns the baud rate of the tty 15fff0a2caSNicolas Pitre * 16fff0a2caSNicolas Pitre * Note that the baud_table needs to be kept in sync with the 17fff0a2caSNicolas Pitre * include/asm/termbits.h file. 18fff0a2caSNicolas Pitre */ 19fff0a2caSNicolas Pitre static const speed_t baud_table[] = { 206ada6064SAndy Shevchenko 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 216ada6064SAndy Shevchenko 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 22fff0a2caSNicolas Pitre #ifdef __sparc__ 231ddeb5a7SAndy Shevchenko 76800, 153600, 307200, 614400, 921600, 500000, 576000, 241ddeb5a7SAndy Shevchenko 1000000, 1152000, 1500000, 2000000 25fff0a2caSNicolas Pitre #else 26fff0a2caSNicolas Pitre 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, 27fff0a2caSNicolas Pitre 2500000, 3000000, 3500000, 4000000 28fff0a2caSNicolas Pitre #endif 29fff0a2caSNicolas Pitre }; 30fff0a2caSNicolas Pitre 31fff0a2caSNicolas Pitre static const tcflag_t baud_bits[] = { 326ada6064SAndy Shevchenko B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400, 336ada6064SAndy Shevchenko B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800, 346ada6064SAndy Shevchenko #ifdef __sparc__ 351ddeb5a7SAndy Shevchenko B76800, B153600, B307200, B614400, B921600, B500000, B576000, 361ddeb5a7SAndy Shevchenko B1000000, B1152000, B1500000, B2000000 37fff0a2caSNicolas Pitre #else 386ada6064SAndy Shevchenko B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000, 396ada6064SAndy Shevchenko B2500000, B3000000, B3500000, B4000000 40fff0a2caSNicolas Pitre #endif 416ada6064SAndy Shevchenko }; 42fff0a2caSNicolas Pitre 43fff0a2caSNicolas Pitre static int n_baud_table = ARRAY_SIZE(baud_table); 44fff0a2caSNicolas Pitre 45fff0a2caSNicolas Pitre /** 46fff0a2caSNicolas Pitre * tty_termios_baud_rate 47fff0a2caSNicolas Pitre * @termios: termios structure 48fff0a2caSNicolas Pitre * 49fff0a2caSNicolas Pitre * Convert termios baud rate data into a speed. This should be called 50fff0a2caSNicolas Pitre * with the termios lock held if this termios is a terminal termios 51fff0a2caSNicolas Pitre * structure. May change the termios data. Device drivers can call this 52fff0a2caSNicolas Pitre * function but should use ->c_[io]speed directly as they are updated. 53fff0a2caSNicolas Pitre * 54fff0a2caSNicolas Pitre * Locking: none 55fff0a2caSNicolas Pitre */ 56fff0a2caSNicolas Pitre 57fff0a2caSNicolas Pitre speed_t tty_termios_baud_rate(struct ktermios *termios) 58fff0a2caSNicolas Pitre { 59fff0a2caSNicolas Pitre unsigned int cbaud; 60fff0a2caSNicolas Pitre 61fff0a2caSNicolas Pitre cbaud = termios->c_cflag & CBAUD; 62fff0a2caSNicolas Pitre 63fff0a2caSNicolas Pitre #ifdef BOTHER 64fff0a2caSNicolas Pitre /* Magic token for arbitrary speed via c_ispeed/c_ospeed */ 65fff0a2caSNicolas Pitre if (cbaud == BOTHER) 66fff0a2caSNicolas Pitre return termios->c_ospeed; 67fff0a2caSNicolas Pitre #endif 68fff0a2caSNicolas Pitre if (cbaud & CBAUDEX) { 69fff0a2caSNicolas Pitre cbaud &= ~CBAUDEX; 70fff0a2caSNicolas Pitre 71fff0a2caSNicolas Pitre if (cbaud < 1 || cbaud + 15 > n_baud_table) 72fff0a2caSNicolas Pitre termios->c_cflag &= ~CBAUDEX; 73fff0a2caSNicolas Pitre else 74fff0a2caSNicolas Pitre cbaud += 15; 75fff0a2caSNicolas Pitre } 76991a2519SH. Peter Anvin return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; 77fff0a2caSNicolas Pitre } 78fff0a2caSNicolas Pitre EXPORT_SYMBOL(tty_termios_baud_rate); 79fff0a2caSNicolas Pitre 80fff0a2caSNicolas Pitre /** 81fff0a2caSNicolas Pitre * tty_termios_input_baud_rate 82fff0a2caSNicolas Pitre * @termios: termios structure 83fff0a2caSNicolas Pitre * 84fff0a2caSNicolas Pitre * Convert termios baud rate data into a speed. This should be called 85fff0a2caSNicolas Pitre * with the termios lock held if this termios is a terminal termios 86fff0a2caSNicolas Pitre * structure. May change the termios data. Device drivers can call this 87fff0a2caSNicolas Pitre * function but should use ->c_[io]speed directly as they are updated. 88fff0a2caSNicolas Pitre * 89fff0a2caSNicolas Pitre * Locking: none 90fff0a2caSNicolas Pitre */ 91fff0a2caSNicolas Pitre 92fff0a2caSNicolas Pitre speed_t tty_termios_input_baud_rate(struct ktermios *termios) 93fff0a2caSNicolas Pitre { 94fff0a2caSNicolas Pitre #ifdef IBSHIFT 95fff0a2caSNicolas Pitre unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD; 96fff0a2caSNicolas Pitre 97fff0a2caSNicolas Pitre if (cbaud == B0) 98fff0a2caSNicolas Pitre return tty_termios_baud_rate(termios); 99fefe287eSJohan Hovold #ifdef BOTHER 100fff0a2caSNicolas Pitre /* Magic token for arbitrary speed via c_ispeed*/ 101fff0a2caSNicolas Pitre if (cbaud == BOTHER) 102fff0a2caSNicolas Pitre return termios->c_ispeed; 103fefe287eSJohan Hovold #endif 104fff0a2caSNicolas Pitre if (cbaud & CBAUDEX) { 105fff0a2caSNicolas Pitre cbaud &= ~CBAUDEX; 106fff0a2caSNicolas Pitre 107fff0a2caSNicolas Pitre if (cbaud < 1 || cbaud + 15 > n_baud_table) 108fff0a2caSNicolas Pitre termios->c_cflag &= ~(CBAUDEX << IBSHIFT); 109fff0a2caSNicolas Pitre else 110fff0a2caSNicolas Pitre cbaud += 15; 111fff0a2caSNicolas Pitre } 112991a2519SH. Peter Anvin return cbaud >= n_baud_table ? 0 : baud_table[cbaud]; 113fefe287eSJohan Hovold #else /* IBSHIFT */ 114fff0a2caSNicolas Pitre return tty_termios_baud_rate(termios); 115fefe287eSJohan Hovold #endif /* IBSHIFT */ 116fff0a2caSNicolas Pitre } 117fff0a2caSNicolas Pitre EXPORT_SYMBOL(tty_termios_input_baud_rate); 118fff0a2caSNicolas Pitre 119fff0a2caSNicolas Pitre /** 120fff0a2caSNicolas Pitre * tty_termios_encode_baud_rate 121fff0a2caSNicolas Pitre * @termios: ktermios structure holding user requested state 122fa441954SJiri Slaby * @ibaud: input speed 123fa441954SJiri Slaby * @obaud: output speed 124fff0a2caSNicolas Pitre * 125fff0a2caSNicolas Pitre * Encode the speeds set into the passed termios structure. This is 126fff0a2caSNicolas Pitre * used as a library helper for drivers so that they can report back 127fff0a2caSNicolas Pitre * the actual speed selected when it differs from the speed requested 128fff0a2caSNicolas Pitre * 129fff0a2caSNicolas Pitre * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour 130fff0a2caSNicolas Pitre * we need to carefully set the bits when the user does not get the 131fff0a2caSNicolas Pitre * desired speed. We allow small margins and preserve as much of possible 132fff0a2caSNicolas Pitre * of the input intent to keep compatibility. 133fff0a2caSNicolas Pitre * 134fff0a2caSNicolas Pitre * Locking: Caller should hold termios lock. This is already held 135fff0a2caSNicolas Pitre * when calling this function from the driver termios handler. 136fff0a2caSNicolas Pitre * 137fff0a2caSNicolas Pitre * The ifdefs deal with platforms whose owners have yet to update them 138fff0a2caSNicolas Pitre * and will all go away once this is done. 139fff0a2caSNicolas Pitre */ 140fff0a2caSNicolas Pitre 141fff0a2caSNicolas Pitre void tty_termios_encode_baud_rate(struct ktermios *termios, 142fff0a2caSNicolas Pitre speed_t ibaud, speed_t obaud) 143fff0a2caSNicolas Pitre { 144fff0a2caSNicolas Pitre int i = 0; 145fff0a2caSNicolas Pitre int ifound = -1, ofound = -1; 146fff0a2caSNicolas Pitre int iclose = ibaud/50, oclose = obaud/50; 147fff0a2caSNicolas Pitre int ibinput = 0; 148fff0a2caSNicolas Pitre 149fff0a2caSNicolas Pitre if (obaud == 0) /* CD dropped */ 150fff0a2caSNicolas Pitre ibaud = 0; /* Clear ibaud to be sure */ 151fff0a2caSNicolas Pitre 152fff0a2caSNicolas Pitre termios->c_ispeed = ibaud; 153fff0a2caSNicolas Pitre termios->c_ospeed = obaud; 154fff0a2caSNicolas Pitre 155fefe287eSJohan Hovold #ifdef IBSHIFT 1561cee38f0SJohan Hovold if ((termios->c_cflag >> IBSHIFT) & CBAUD) 1571cee38f0SJohan Hovold ibinput = 1; /* An input speed was specified */ 158fefe287eSJohan Hovold #endif 159fefe287eSJohan Hovold #ifdef BOTHER 160fff0a2caSNicolas Pitre /* If the user asked for a precise weird speed give a precise weird 161fff0a2caSNicolas Pitre answer. If they asked for a Bfoo speed they may have problems 162fff0a2caSNicolas Pitre digesting non-exact replies so fuzz a bit */ 163fff0a2caSNicolas Pitre 1641cee38f0SJohan Hovold if ((termios->c_cflag & CBAUD) == BOTHER) { 165fff0a2caSNicolas Pitre oclose = 0; 1661cee38f0SJohan Hovold if (!ibinput) 1671cee38f0SJohan Hovold iclose = 0; 1681cee38f0SJohan Hovold } 169fff0a2caSNicolas Pitre if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) 170fff0a2caSNicolas Pitre iclose = 0; 171fff0a2caSNicolas Pitre #endif 172fff0a2caSNicolas Pitre termios->c_cflag &= ~CBAUD; 173fada18c4SJohan Hovold #ifdef IBSHIFT 174fada18c4SJohan Hovold termios->c_cflag &= ~(CBAUD << IBSHIFT); 175fada18c4SJohan Hovold #endif 176fff0a2caSNicolas Pitre 177fff0a2caSNicolas Pitre /* 178fff0a2caSNicolas Pitre * Our goal is to find a close match to the standard baud rate 179fff0a2caSNicolas Pitre * returned. Walk the baud rate table and if we get a very close 180fff0a2caSNicolas Pitre * match then report back the speed as a POSIX Bxxxx value by 181fff0a2caSNicolas Pitre * preference 182fff0a2caSNicolas Pitre */ 183fff0a2caSNicolas Pitre 184fff0a2caSNicolas Pitre do { 185fff0a2caSNicolas Pitre if (obaud - oclose <= baud_table[i] && 186fff0a2caSNicolas Pitre obaud + oclose >= baud_table[i]) { 187fff0a2caSNicolas Pitre termios->c_cflag |= baud_bits[i]; 188fff0a2caSNicolas Pitre ofound = i; 189fff0a2caSNicolas Pitre } 190fff0a2caSNicolas Pitre if (ibaud - iclose <= baud_table[i] && 191fff0a2caSNicolas Pitre ibaud + iclose >= baud_table[i]) { 192fff0a2caSNicolas Pitre /* For the case input == output don't set IBAUD bits 193fff0a2caSNicolas Pitre if the user didn't do so */ 194fff0a2caSNicolas Pitre if (ofound == i && !ibinput) 195fff0a2caSNicolas Pitre ifound = i; 196fff0a2caSNicolas Pitre #ifdef IBSHIFT 197fff0a2caSNicolas Pitre else { 198fff0a2caSNicolas Pitre ifound = i; 199fff0a2caSNicolas Pitre termios->c_cflag |= (baud_bits[i] << IBSHIFT); 200fff0a2caSNicolas Pitre } 201fff0a2caSNicolas Pitre #endif 202fff0a2caSNicolas Pitre } 203fff0a2caSNicolas Pitre } while (++i < n_baud_table); 204fff0a2caSNicolas Pitre 205fff0a2caSNicolas Pitre /* 206fff0a2caSNicolas Pitre * If we found no match then use BOTHER if provided or warn 207fff0a2caSNicolas Pitre * the user their platform maintainer needs to wake up if not. 208fff0a2caSNicolas Pitre */ 209fff0a2caSNicolas Pitre #ifdef BOTHER 210fff0a2caSNicolas Pitre if (ofound == -1) 211fff0a2caSNicolas Pitre termios->c_cflag |= BOTHER; 212fff0a2caSNicolas Pitre /* Set exact input bits only if the input and output differ or the 213fff0a2caSNicolas Pitre user already did */ 214fff0a2caSNicolas Pitre if (ifound == -1 && (ibaud != obaud || ibinput)) 215fff0a2caSNicolas Pitre termios->c_cflag |= (BOTHER << IBSHIFT); 216fff0a2caSNicolas Pitre #else 217fff0a2caSNicolas Pitre if (ifound == -1 || ofound == -1) 218fff0a2caSNicolas Pitre pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n"); 219fff0a2caSNicolas Pitre #endif 220fff0a2caSNicolas Pitre } 221fff0a2caSNicolas Pitre EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate); 222fff0a2caSNicolas Pitre 223fff0a2caSNicolas Pitre /** 224fff0a2caSNicolas Pitre * tty_encode_baud_rate - set baud rate of the tty 225fff0a2caSNicolas Pitre * @ibaud: input baud rate 226fa441954SJiri Slaby * @obaud: output baud rate 227fff0a2caSNicolas Pitre * 228fff0a2caSNicolas Pitre * Update the current termios data for the tty with the new speed 229fff0a2caSNicolas Pitre * settings. The caller must hold the termios_rwsem for the tty in 230fff0a2caSNicolas Pitre * question. 231fff0a2caSNicolas Pitre */ 232fff0a2caSNicolas Pitre 233fff0a2caSNicolas Pitre void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud) 234fff0a2caSNicolas Pitre { 235fff0a2caSNicolas Pitre tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud); 236fff0a2caSNicolas Pitre } 237fff0a2caSNicolas Pitre EXPORT_SYMBOL_GPL(tty_encode_baud_rate); 238