[linux-2.6-block.git] / drivers / tty / tty_baudrate.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/termios.h>
#include <linux/tty.h>
#include <linux/export.h>
#include "tty.h"


/*
 * Routine which returns the baud rate of the tty
 *
 * Note that the baud_table needs to be kept in sync with the
 * include/asm/termbits.h file.
 */
static const speed_t baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
	4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
#ifdef __sparc__
	76800, 153600, 307200, 614400, 921600, 500000, 576000,
	1000000, 1152000, 1500000, 2000000
#else
	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	2500000, 3000000, 3500000, 4000000
#endif
};

static const tcflag_t baud_bits[] = {
	B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400,
	B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800,
#ifdef __sparc__
	B76800, B153600, B307200, B614400, B921600, B500000, B576000,
	B1000000, B1152000, B1500000, B2000000
#else
	B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000,
	B2500000, B3000000, B3500000, B4000000
#endif
};

static int n_baud_table = ARRAY_SIZE(baud_table);

/**
 *	tty_termios_baud_rate
 *	@termios: termios structure
 *
 *	Convert termios baud rate data into a speed. This should be called
 *	with the termios lock held if this termios is a terminal termios
 *	structure. May change the termios data. Device drivers can call this
 *	function but should use ->c_[io]speed directly as they are updated.
 *
 *	Locking: none
 */

speed_t tty_termios_baud_rate(struct ktermios *termios)
{
	unsigned int cbaud;

	cbaud = termios->c_cflag & CBAUD;

	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
	if (cbaud == BOTHER)
		return termios->c_ospeed;

	if (cbaud & CBAUDEX) {
		cbaud &= ~CBAUDEX;

		if (cbaud < 1 || cbaud + 15 > n_baud_table)
			termios->c_cflag &= ~CBAUDEX;
		else
			cbaud += 15;
	}
	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
}
EXPORT_SYMBOL(tty_termios_baud_rate);

/**
 *	tty_termios_input_baud_rate
 *	@termios: termios structure
 *
 *	Convert termios baud rate data into a speed. This should be called
 *	with the termios lock held if this termios is a terminal termios
 *	structure. May change the termios data. Device drivers can call this
 *	function but should use ->c_[io]speed directly as they are updated.
 *
 *	Locking: none
 */

speed_t tty_termios_input_baud_rate(struct ktermios *termios)
{
	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;

	if (cbaud == B0)
		return tty_termios_baud_rate(termios);

	/* Magic token for arbitrary speed via c_ispeed*/
	if (cbaud == BOTHER)
		return termios->c_ispeed;

	if (cbaud & CBAUDEX) {
		cbaud &= ~CBAUDEX;

		if (cbaud < 1 || cbaud + 15 > n_baud_table)
			termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
		else
			cbaud += 15;
	}
	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
}
EXPORT_SYMBOL(tty_termios_input_baud_rate);

/**
 *	tty_termios_encode_baud_rate
 *	@termios: ktermios structure holding user requested state
 *	@ibaud: input speed
 *	@obaud: output speed
 *
 *	Encode the speeds set into the passed termios structure. This is
 *	used as a library helper for drivers so that they can report back
 *	the actual speed selected when it differs from the speed requested
 *
 *	For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
 *	we need to carefully set the bits when the user does not get the
 *	desired speed. We allow small margins and preserve as much of possible
 *	of the input intent to keep compatibility.
 *
 *	Locking: Caller should hold termios lock. This is already held
 *	when calling this function from the driver termios handler.
 *
 *	The ifdefs deal with platforms whose owners have yet to update them
 *	and will all go away once this is done.
 */

void tty_termios_encode_baud_rate(struct ktermios *termios,
				  speed_t ibaud, speed_t obaud)
{
	int i = 0;
	int ifound = -1, ofound = -1;
	int iclose = ibaud/50, oclose = obaud/50;
	int ibinput = 0;

	if (obaud == 0)			/* CD dropped */
		ibaud = 0;		/* Clear ibaud to be sure */

	termios->c_ispeed = ibaud;
	termios->c_ospeed = obaud;

	if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
		ibinput = 1;	/* An input speed was specified */

	/* If the user asked for a precise weird speed give a precise weird
	 * answer. If they asked for a Bfoo speed they may have problems
	 * digesting non-exact replies so fuzz a bit.
	 */

	if ((termios->c_cflag & CBAUD) == BOTHER) {
		oclose = 0;
		if (!ibinput)
			iclose = 0;
	}
	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
		iclose = 0;

	termios->c_cflag &= ~CBAUD;
	termios->c_cflag &= ~(CBAUD << IBSHIFT);

	/*
	 *	Our goal is to find a close match to the standard baud rate
	 *	returned. Walk the baud rate table and if we get a very close
	 *	match then report back the speed as a POSIX Bxxxx value by
	 *	preference
	 */

	do {
		if (obaud - oclose <= baud_table[i] &&
		    obaud + oclose >= baud_table[i]) {
			termios->c_cflag |= baud_bits[i];
			ofound = i;
		}
		if (ibaud - iclose <= baud_table[i] &&
		    ibaud + iclose >= baud_table[i]) {
			/* For the case input == output don't set IBAUD bits
			 * if the user didn't do so.
			 */
			if (ofound == i && !ibinput) {
				ifound  = i;
			} else {
				ifound = i;
				termios->c_cflag |= (baud_bits[i] << IBSHIFT);
			}
		}
	} while (++i < n_baud_table);

	/* If we found no match then use BOTHER. */
	if (ofound == -1)
		termios->c_cflag |= BOTHER;
	/* Set exact input bits only if the input and output differ or the
	 * user already did.
	 */
	if (ifound == -1 && (ibaud != obaud || ibinput))
		termios->c_cflag |= (BOTHER << IBSHIFT);
}
EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);

/**
 *	tty_encode_baud_rate		-	set baud rate of the tty
 *	@tty:   terminal device
 *	@ibaud: input baud rate
 *	@obaud: output baud rate
 *
 *	Update the current termios data for the tty with the new speed
 *	settings. The caller must hold the termios_rwsem for the tty in
 *	question.
 */

void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
{
	tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
}
EXPORT_SYMBOL_GPL(tty_encode_baud_rate);
Commit	Line	Data
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>
5ffa6e34	11	#include "tty.h"
fff0a2ca NP	12
	13
	14	/*
	15	* Routine which returns the baud rate of the tty
	16	*
	17	* Note that the baud_table needs to be kept in sync with the
	18	* include/asm/termbits.h file.
	19	*/
	20	static const speed_t baud_table[] = {
6ada6064 AS	21	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
6ada6064 AS	22	4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
fff0a2ca	23	#ifdef __sparc__
1ddeb5a7 AS	24	76800, 153600, 307200, 614400, 921600, 500000, 576000,
1ddeb5a7 AS	25	1000000, 1152000, 1500000, 2000000
fff0a2ca NP	26	#else
	27	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	28	2500000, 3000000, 3500000, 4000000
	29	#endif
	30	};
	31
fff0a2ca	32	static const tcflag_t baud_bits[] = {
6ada6064 AS	33	B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400,
	34	B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800,
	35	#ifdef __sparc__
1ddeb5a7 AS	36	B76800, B153600, B307200, B614400, B921600, B500000, B576000,
1ddeb5a7 AS	37	B1000000, B1152000, B1500000, B2000000
fff0a2ca	38	#else
6ada6064 AS	39	B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000,
6ada6064 AS	40	B2500000, B3000000, B3500000, B4000000
fff0a2ca	41	#endif
6ada6064	42	};
fff0a2ca NP	43
	44	static int n_baud_table = ARRAY_SIZE(baud_table);
	45
	46	/**
	47	* tty_termios_baud_rate
	48	* @termios: termios structure
	49	*
	50	* Convert termios baud rate data into a speed. This should be called
	51	* with the termios lock held if this termios is a terminal termios
	52	* structure. May change the termios data. Device drivers can call this
	53	* function but should use ->c_[io]speed directly as they are updated.
	54	*
	55	* Locking: none
	56	*/
	57
	58	speed_t tty_termios_baud_rate(struct ktermios *termios)
	59	{
	60	unsigned int cbaud;
	61
	62	cbaud = termios->c_cflag & CBAUD;
	63
fff0a2ca NP	64	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
	65	if (cbaud == BOTHER)
	66	return termios->c_ospeed;
69648d7b	67
fff0a2ca NP	68	if (cbaud & CBAUDEX) {
	69	cbaud &= ~CBAUDEX;
	70
	71	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	72	termios->c_cflag &= ~CBAUDEX;
	73	else
	74	cbaud += 15;
	75	}
991a2519	76	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
fff0a2ca NP	77	}
	78	EXPORT_SYMBOL(tty_termios_baud_rate);
	79
	80	/**
	81	* tty_termios_input_baud_rate
	82	* @termios: termios structure
	83	*
	84	* Convert termios baud rate data into a speed. This should be called
	85	* with the termios lock held if this termios is a terminal termios
	86	* structure. May change the termios data. Device drivers can call this
	87	* function but should use ->c_[io]speed directly as they are updated.
	88	*
	89	* Locking: none
	90	*/
	91
	92	speed_t tty_termios_input_baud_rate(struct ktermios *termios)
	93	{
fff0a2ca NP	94	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
	95
	96	if (cbaud == B0)
	97	return tty_termios_baud_rate(termios);
69648d7b	98
fff0a2ca NP	99	/* Magic token for arbitrary speed via c_ispeed*/
	100	if (cbaud == BOTHER)
	101	return termios->c_ispeed;
69648d7b	102
fff0a2ca NP	103	if (cbaud & CBAUDEX) {
	104	cbaud &= ~CBAUDEX;
	105
	106	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	107	termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
	108	else
	109	cbaud += 15;
	110	}
991a2519	111	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
fff0a2ca NP	112	}
	113	EXPORT_SYMBOL(tty_termios_input_baud_rate);
	114
	115	/**
	116	* tty_termios_encode_baud_rate
	117	* @termios: ktermios structure holding user requested state
fa441954 JS	118	* @ibaud: input speed
fa441954 JS	119	* @obaud: output speed
fff0a2ca NP	120	*
	121	* Encode the speeds set into the passed termios structure. This is
	122	* used as a library helper for drivers so that they can report back
	123	* the actual speed selected when it differs from the speed requested
	124	*
	125	* For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
	126	* we need to carefully set the bits when the user does not get the
	127	* desired speed. We allow small margins and preserve as much of possible
	128	* of the input intent to keep compatibility.
	129	*
	130	* Locking: Caller should hold termios lock. This is already held
	131	* when calling this function from the driver termios handler.
	132	*
	133	* The ifdefs deal with platforms whose owners have yet to update them
	134	* and will all go away once this is done.
	135	*/
	136
	137	void tty_termios_encode_baud_rate(struct ktermios *termios,
	138	speed_t ibaud, speed_t obaud)
	139	{
	140	int i = 0;
	141	int ifound = -1, ofound = -1;
	142	int iclose = ibaud/50, oclose = obaud/50;
	143	int ibinput = 0;
	144
eb460edb	145	if (obaud == 0) /* CD dropped */
fff0a2ca NP	146	ibaud = 0; /* Clear ibaud to be sure */
	147
	148	termios->c_ispeed = ibaud;
	149	termios->c_ospeed = obaud;
	150
4545b069	151	if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
1cee38f0	152	ibinput = 1; /* An input speed was specified */
9cca25e2	153
fff0a2ca	154	/* If the user asked for a precise weird speed give a precise weird
ad48749b XT	155	* answer. If they asked for a Bfoo speed they may have problems
	156	* digesting non-exact replies so fuzz a bit.
	157	*/
fff0a2ca	158
1cee38f0	159	if ((termios->c_cflag & CBAUD) == BOTHER) {
fff0a2ca	160	oclose = 0;
1cee38f0 JH	161	if (!ibinput)
	162	iclose = 0;
	163	}
fff0a2ca NP	164	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
fff0a2ca NP	165	iclose = 0;
69648d7b	166
fff0a2ca	167	termios->c_cflag &= ~CBAUD;
fada18c4	168	termios->c_cflag &= ~(CBAUD << IBSHIFT);
fff0a2ca NP	169
	170	/*
	171	* Our goal is to find a close match to the standard baud rate
	172	* returned. Walk the baud rate table and if we get a very close
	173	* match then report back the speed as a POSIX Bxxxx value by
	174	* preference
	175	*/
	176
	177	do {
	178	if (obaud - oclose <= baud_table[i] &&
	179	obaud + oclose >= baud_table[i]) {
	180	termios->c_cflag \|= baud_bits[i];
	181	ofound = i;
	182	}
	183	if (ibaud - iclose <= baud_table[i] &&
	184	ibaud + iclose >= baud_table[i]) {
	185	/* For the case input == output don't set IBAUD bits
ad48749b XT	186	* if the user didn't do so.
ad48749b XT	187	*/
9cca25e2	188	if (ofound == i && !ibinput) {
fff0a2ca	189	ifound = i;
9cca25e2	190	} else {
fff0a2ca NP	191	ifound = i;
	192	termios->c_cflag \|= (baud_bits[i] << IBSHIFT);
	193	}
fff0a2ca NP	194	}
	195	} while (++i < n_baud_table);
	196
69648d7b	197	/* If we found no match then use BOTHER. */
fff0a2ca NP	198	if (ofound == -1)
	199	termios->c_cflag \|= BOTHER;
	200	/* Set exact input bits only if the input and output differ or the
ad48749b XT	201	* user already did.
ad48749b XT	202	*/
fff0a2ca NP	203	if (ifound == -1 && (ibaud != obaud \|\| ibinput))
fff0a2ca NP	204	termios->c_cflag \|= (BOTHER << IBSHIFT);
fff0a2ca NP	205	}
	206	EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
	207
	208	/**
	209	* tty_encode_baud_rate - set baud rate of the tty
6e30f283	210	* @tty: terminal device
fff0a2ca	211	* @ibaud: input baud rate
fa441954	212	* @obaud: output baud rate
fff0a2ca NP	213	*
	214	* Update the current termios data for the tty with the new speed
	215	* settings. The caller must hold the termios_rwsem for the tty in
	216	* question.
	217	*/
	218
	219	void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
	220	{
	221	tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
	222	}
	223	EXPORT_SYMBOL_GPL(tty_encode_baud_rate);