[mirror_ubuntu-hirsute-kernel.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>


/*
 * 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)
		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>
	11
	12
	13	/*
	14	* Routine which returns the baud rate of the tty
	15	*
	16	* Note that the baud_table needs to be kept in sync with the
	17	* include/asm/termbits.h file.
	18	*/
	19	static const speed_t baud_table[] = {
6ada6064 AS	20	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
6ada6064 AS	21	4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
fff0a2ca	22	#ifdef __sparc__
1ddeb5a7 AS	23	76800, 153600, 307200, 614400, 921600, 500000, 576000,
1ddeb5a7 AS	24	1000000, 1152000, 1500000, 2000000
fff0a2ca NP	25	#else
	26	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	27	2500000, 3000000, 3500000, 4000000
	28	#endif
	29	};
	30
fff0a2ca	31	static const tcflag_t baud_bits[] = {
6ada6064 AS	32	B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400,
	33	B4800, B9600, B19200, B38400, B57600, B115200, B230400, B460800,
	34	#ifdef __sparc__
1ddeb5a7 AS	35	B76800, B153600, B307200, B614400, B921600, B500000, B576000,
1ddeb5a7 AS	36	B1000000, B1152000, B1500000, B2000000
fff0a2ca	37	#else
6ada6064 AS	38	B500000, B576000, B921600, B1000000, B1152000, B1500000, B2000000,
6ada6064 AS	39	B2500000, B3000000, B3500000, B4000000
fff0a2ca	40	#endif
6ada6064	41	};
fff0a2ca NP	42
	43	static int n_baud_table = ARRAY_SIZE(baud_table);
	44
	45	/**
	46	* tty_termios_baud_rate
	47	* @termios: termios structure
	48	*
	49	* Convert termios baud rate data into a speed. This should be called
	50	* with the termios lock held if this termios is a terminal termios
	51	* structure. May change the termios data. Device drivers can call this
	52	* function but should use ->c_[io]speed directly as they are updated.
	53	*
	54	* Locking: none
	55	*/
	56
	57	speed_t tty_termios_baud_rate(struct ktermios *termios)
	58	{
	59	unsigned int cbaud;
	60
	61	cbaud = termios->c_cflag & CBAUD;
	62
	63	#ifdef BOTHER
	64	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
	65	if (cbaud == BOTHER)
	66	return termios->c_ospeed;
	67	#endif
	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	{
	94	#ifdef IBSHIFT
	95	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
	96
	97	if (cbaud == B0)
	98	return tty_termios_baud_rate(termios);
fefe287e	99	#ifdef BOTHER
fff0a2ca NP	100	/* Magic token for arbitrary speed via c_ispeed*/
	101	if (cbaud == BOTHER)
	102	return termios->c_ispeed;
fefe287e	103	#endif
fff0a2ca NP	104	if (cbaud & CBAUDEX) {
	105	cbaud &= ~CBAUDEX;
	106
	107	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	108	termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
	109	else
	110	cbaud += 15;
	111	}
991a2519	112	return cbaud >= n_baud_table ? 0 : baud_table[cbaud];
fefe287e	113	#else /* IBSHIFT */
fff0a2ca	114	return tty_termios_baud_rate(termios);
fefe287e	115	#endif /* IBSHIFT */
fff0a2ca NP	116	}
	117	EXPORT_SYMBOL(tty_termios_input_baud_rate);
	118
	119	/**
	120	* tty_termios_encode_baud_rate
	121	* @termios: ktermios structure holding user requested state
fa441954 JS	122	* @ibaud: input speed
fa441954 JS	123	* @obaud: output speed
fff0a2ca NP	124	*
	125	* Encode the speeds set into the passed termios structure. This is
	126	* used as a library helper for drivers so that they can report back
	127	* the actual speed selected when it differs from the speed requested
	128	*
	129	* For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
	130	* we need to carefully set the bits when the user does not get the
	131	* desired speed. We allow small margins and preserve as much of possible
	132	* of the input intent to keep compatibility.
	133	*
	134	* Locking: Caller should hold termios lock. This is already held
	135	* when calling this function from the driver termios handler.
	136	*
	137	* The ifdefs deal with platforms whose owners have yet to update them
	138	* and will all go away once this is done.
	139	*/
	140
	141	void tty_termios_encode_baud_rate(struct ktermios *termios,
	142	speed_t ibaud, speed_t obaud)
	143	{
	144	int i = 0;
	145	int ifound = -1, ofound = -1;
	146	int iclose = ibaud/50, oclose = obaud/50;
	147	int ibinput = 0;
	148
	149	if (obaud == 0) /* CD dropped */
	150	ibaud = 0; /* Clear ibaud to be sure */
	151
	152	termios->c_ispeed = ibaud;
	153	termios->c_ospeed = obaud;
	154
fefe287e	155	#ifdef IBSHIFT
1cee38f0 JH	156	if ((termios->c_cflag >> IBSHIFT) & CBAUD)
1cee38f0 JH	157	ibinput = 1; /* An input speed was specified */
fefe287e JH	158	#endif
fefe287e JH	159	#ifdef BOTHER
fff0a2ca NP	160	/* If the user asked for a precise weird speed give a precise weird
	161	answer. If they asked for a Bfoo speed they may have problems
	162	digesting non-exact replies so fuzz a bit */
	163
1cee38f0	164	if ((termios->c_cflag & CBAUD) == BOTHER) {
fff0a2ca	165	oclose = 0;
1cee38f0 JH	166	if (!ibinput)
	167	iclose = 0;
	168	}
fff0a2ca NP	169	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
fff0a2ca NP	170	iclose = 0;
fff0a2ca NP	171	#endif
fff0a2ca NP	172	termios->c_cflag &= ~CBAUD;
fada18c4 JH	173	#ifdef IBSHIFT
	174	termios->c_cflag &= ~(CBAUD << IBSHIFT);
	175	#endif
fff0a2ca NP	176
	177	/*
	178	* Our goal is to find a close match to the standard baud rate
	179	* returned. Walk the baud rate table and if we get a very close
	180	* match then report back the speed as a POSIX Bxxxx value by
	181	* preference
	182	*/
	183
	184	do {
	185	if (obaud - oclose <= baud_table[i] &&
	186	obaud + oclose >= baud_table[i]) {
	187	termios->c_cflag \|= baud_bits[i];
	188	ofound = i;
	189	}
	190	if (ibaud - iclose <= baud_table[i] &&
	191	ibaud + iclose >= baud_table[i]) {
	192	/* For the case input == output don't set IBAUD bits
	193	if the user didn't do so */
	194	if (ofound == i && !ibinput)
	195	ifound = i;
	196	#ifdef IBSHIFT
	197	else {
	198	ifound = i;
	199	termios->c_cflag \|= (baud_bits[i] << IBSHIFT);
	200	}
	201	#endif
	202	}
	203	} while (++i < n_baud_table);
	204
	205	/*
	206	* If we found no match then use BOTHER if provided or warn
	207	* the user their platform maintainer needs to wake up if not.
	208	*/
	209	#ifdef BOTHER
	210	if (ofound == -1)
	211	termios->c_cflag \|= BOTHER;
	212	/* Set exact input bits only if the input and output differ or the
	213	user already did */
	214	if (ifound == -1 && (ibaud != obaud \|\| ibinput))
	215	termios->c_cflag \|= (BOTHER << IBSHIFT);
	216	#else
	217	if (ifound == -1 \|\| ofound == -1)
	218	pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n");
	219	#endif
	220	}
	221	EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
	222
	223	/**
	224	* tty_encode_baud_rate - set baud rate of the tty
6e30f283	225	* @tty: terminal device
fff0a2ca	226	* @ibaud: input baud rate
fa441954	227	* @obaud: output baud rate
fff0a2ca NP	228	*
	229	* Update the current termios data for the tty with the new speed
	230	* settings. The caller must hold the termios_rwsem for the tty in
	231	* question.
	232	*/
	233
	234	void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
	235	{
	236	tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
	237	}
	238	EXPORT_SYMBOL_GPL(tty_encode_baud_rate);