[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;

#ifdef BOTHER
	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
	if (cbaud == BOTHER)
		return termios->c_ospeed;
#endif
	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)
{
#ifdef IBSHIFT
	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;

	if (cbaud == B0)
		return tty_termios_baud_rate(termios);
#ifdef BOTHER
	/* Magic token for arbitrary speed via c_ispeed*/
	if (cbaud == BOTHER)
		return termios->c_ispeed;
#endif
	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];
#else	/* IBSHIFT */
	return tty_termios_baud_rate(termios);
#endif	/* IBSHIFT */
}
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;

#ifdef IBSHIFT
	if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
		ibinput = 1;	/* An input speed was specified */
#endif
#ifdef BOTHER
	/* 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;
#endif
	termios->c_cflag &= ~CBAUD;
#ifdef IBSHIFT
	termios->c_cflag &= ~(CBAUD << IBSHIFT);
#endif

	/*
	 *	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;
#ifdef IBSHIFT
			else {
				ifound = i;
				termios->c_cflag |= (baud_bits[i] << IBSHIFT);
			}
#endif
		}
	} while (++i < n_baud_table);

	/*
	 *	If we found no match then use BOTHER if provided or warn
	 *	the user their platform maintainer needs to wake up if not.
	 */
#ifdef 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);
#else
	if (ifound == -1 || ofound == -1)
		pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n");
#endif
}
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
	64	#ifdef BOTHER
	65	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
	66	if (cbaud == BOTHER)
	67	return termios->c_ospeed;
	68	#endif
	69	if (cbaud & CBAUDEX) {
	70	cbaud &= ~CBAUDEX;
	71
	72	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	73	termios->c_cflag &= ~CBAUDEX;
	74	else
	75	cbaud += 15;
	76	}
991a2519	77	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
fff0a2ca NP	78	}
	79	EXPORT_SYMBOL(tty_termios_baud_rate);
	80
	81	/**
	82	* tty_termios_input_baud_rate
	83	* @termios: termios structure
	84	*
	85	* Convert termios baud rate data into a speed. This should be called
	86	* with the termios lock held if this termios is a terminal termios
	87	* structure. May change the termios data. Device drivers can call this
	88	* function but should use ->c_[io]speed directly as they are updated.
	89	*
	90	* Locking: none
	91	*/
	92
	93	speed_t tty_termios_input_baud_rate(struct ktermios *termios)
	94	{
	95	#ifdef IBSHIFT
	96	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
	97
	98	if (cbaud == B0)
	99	return tty_termios_baud_rate(termios);
fefe287e	100	#ifdef BOTHER
fff0a2ca NP	101	/* Magic token for arbitrary speed via c_ispeed*/
	102	if (cbaud == BOTHER)
	103	return termios->c_ispeed;
fefe287e	104	#endif
fff0a2ca NP	105	if (cbaud & CBAUDEX) {
	106	cbaud &= ~CBAUDEX;
	107
	108	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	109	termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
	110	else
	111	cbaud += 15;
	112	}
991a2519	113	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
fefe287e	114	#else /* IBSHIFT */
fff0a2ca	115	return tty_termios_baud_rate(termios);
fefe287e	116	#endif /* IBSHIFT */
fff0a2ca NP	117	}
	118	EXPORT_SYMBOL(tty_termios_input_baud_rate);
	119
	120	/**
	121	* tty_termios_encode_baud_rate
	122	* @termios: ktermios structure holding user requested state
fa441954 JS	123	* @ibaud: input speed
fa441954 JS	124	* @obaud: output speed
fff0a2ca NP	125	*
	126	* Encode the speeds set into the passed termios structure. This is
	127	* used as a library helper for drivers so that they can report back
	128	* the actual speed selected when it differs from the speed requested
	129	*
	130	* For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
	131	* we need to carefully set the bits when the user does not get the
	132	* desired speed. We allow small margins and preserve as much of possible
	133	* of the input intent to keep compatibility.
	134	*
	135	* Locking: Caller should hold termios lock. This is already held
	136	* when calling this function from the driver termios handler.
	137	*
	138	* The ifdefs deal with platforms whose owners have yet to update them
	139	* and will all go away once this is done.
	140	*/
	141
	142	void tty_termios_encode_baud_rate(struct ktermios *termios,
	143	speed_t ibaud, speed_t obaud)
	144	{
	145	int i = 0;
	146	int ifound = -1, ofound = -1;
	147	int iclose = ibaud/50, oclose = obaud/50;
	148	int ibinput = 0;
	149
eb460edb	150	if (obaud == 0) /* CD dropped */
fff0a2ca NP	151	ibaud = 0; /* Clear ibaud to be sure */
	152
	153	termios->c_ispeed = ibaud;
	154	termios->c_ospeed = obaud;
	155
fefe287e	156	#ifdef IBSHIFT
4545b069	157	if (((termios->c_cflag >> IBSHIFT) & CBAUD) != B0)
1cee38f0	158	ibinput = 1; /* An input speed was specified */
fefe287e JH	159	#endif
fefe287e JH	160	#ifdef BOTHER
fff0a2ca	161	/* If the user asked for a precise weird speed give a precise weird
ad48749b XT	162	* answer. If they asked for a Bfoo speed they may have problems
	163	* digesting non-exact replies so fuzz a bit.
	164	*/
fff0a2ca	165
1cee38f0	166	if ((termios->c_cflag & CBAUD) == BOTHER) {
fff0a2ca	167	oclose = 0;
1cee38f0 JH	168	if (!ibinput)
	169	iclose = 0;
	170	}
fff0a2ca NP	171	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
fff0a2ca NP	172	iclose = 0;
fff0a2ca NP	173	#endif
fff0a2ca NP	174	termios->c_cflag &= ~CBAUD;
fada18c4 JH	175	#ifdef IBSHIFT
	176	termios->c_cflag &= ~(CBAUD << IBSHIFT);
	177	#endif
fff0a2ca NP	178
	179	/*
	180	* Our goal is to find a close match to the standard baud rate
	181	* returned. Walk the baud rate table and if we get a very close
	182	* match then report back the speed as a POSIX Bxxxx value by
	183	* preference
	184	*/
	185
	186	do {
	187	if (obaud - oclose <= baud_table[i] &&
	188	obaud + oclose >= baud_table[i]) {
	189	termios->c_cflag \|= baud_bits[i];
	190	ofound = i;
	191	}
	192	if (ibaud - iclose <= baud_table[i] &&
	193	ibaud + iclose >= baud_table[i]) {
	194	/* For the case input == output don't set IBAUD bits
ad48749b XT	195	* if the user didn't do so.
ad48749b XT	196	*/
fff0a2ca NP	197	if (ofound == i && !ibinput)
	198	ifound = i;
	199	#ifdef IBSHIFT
	200	else {
	201	ifound = i;
	202	termios->c_cflag \|= (baud_bits[i] << IBSHIFT);
	203	}
	204	#endif
	205	}
	206	} while (++i < n_baud_table);
	207
	208	/*
	209	* If we found no match then use BOTHER if provided or warn
	210	* the user their platform maintainer needs to wake up if not.
	211	*/
	212	#ifdef BOTHER
	213	if (ofound == -1)
	214	termios->c_cflag \|= BOTHER;
	215	/* Set exact input bits only if the input and output differ or the
ad48749b XT	216	* user already did.
ad48749b XT	217	*/
fff0a2ca NP	218	if (ifound == -1 && (ibaud != obaud \|\| ibinput))
	219	termios->c_cflag \|= (BOTHER << IBSHIFT);
	220	#else
	221	if (ifound == -1 \|\| ofound == -1)
	222	pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n");
	223	#endif
	224	}
	225	EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
	226
	227	/**
	228	* tty_encode_baud_rate - set baud rate of the tty
6e30f283	229	* @tty: terminal device
fff0a2ca	230	* @ibaud: input baud rate
fa441954	231	* @obaud: output baud rate
fff0a2ca NP	232	*
	233	* Update the current termios data for the tty with the new speed
	234	* settings. The caller must hold the termios_rwsem for the tty in
	235	* question.
	236	*/
	237
	238	void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
	239	{
	240	tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
	241	}
	242	EXPORT_SYMBOL_GPL(tty_encode_baud_rate);