[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>


/*
 * 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
#else
	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	2500000, 3000000, 3500000, 4000000
#endif
};

#ifndef __sparc__
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, B500000, B576000,
	B921600, B1000000, B1152000, B1500000, B2000000, B2500000,
	B3000000, B3500000, B4000000
};
#else
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, B76800, B153600,
	B307200, B614400, B921600
};
#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 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 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
 *	@ispeed: input speed
 *	@ospeed: 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
 *	@ibaud: input baud rate
 *	@obad: 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[] = {
	20	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	21	9600, 19200, 38400, 57600, 115200, 230400, 460800,
	22	#ifdef __sparc__
	23	76800, 153600, 307200, 614400, 921600
	24	#else
	25	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	26	2500000, 3000000, 3500000, 4000000
	27	#endif
	28	};
	29
	30	#ifndef __sparc__
	31	static const tcflag_t baud_bits[] = {
	32	B0, B50, B75, B110, B134, B150, B200, B300, B600,
	33	B1200, B1800, B2400, B4800, B9600, B19200, B38400,
	34	B57600, B115200, B230400, B460800, B500000, B576000,
	35	B921600, B1000000, B1152000, B1500000, B2000000, B2500000,
	36	B3000000, B3500000, B4000000
	37	};
	38	#else
	39	static const tcflag_t baud_bits[] = {
	40	B0, B50, B75, B110, B134, B150, B200, B300, B600,
	41	B1200, B1800, B2400, B4800, B9600, B19200, B38400,
	42	B57600, B115200, B230400, B460800, B76800, B153600,
	43	B307200, B614400, B921600
	44	};
	45	#endif
	46
	47	static int n_baud_table = ARRAY_SIZE(baud_table);
	48
	49	/**
	50	* tty_termios_baud_rate
	51	* @termios: termios structure
	52	*
	53	* Convert termios baud rate data into a speed. This should be called
	54	* with the termios lock held if this termios is a terminal termios
	55	* structure. May change the termios data. Device drivers can call this
	56	* function but should use ->c_[io]speed directly as they are updated.
	57	*
	58	* Locking: none
	59	*/
	60
	61	speed_t tty_termios_baud_rate(struct ktermios *termios)
	62	{
	63	unsigned int cbaud;
	64
	65	cbaud = termios->c_cflag & CBAUD;
66
67	#ifdef BOTHER
68	/* Magic token for arbitrary speed via c_ispeed/c_ospeed */
69	if (cbaud == BOTHER)
70	return termios->c_ospeed;
71	#endif
72	if (cbaud & CBAUDEX) {
73	cbaud &= ~CBAUDEX;
74
75	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
76	termios->c_cflag &= ~CBAUDEX;
77	else
78	cbaud += 15;
79	}
80	return baud_table[cbaud];
81	}
82	EXPORT_SYMBOL(tty_termios_baud_rate);
83
84	/**
85	* tty_termios_input_baud_rate
86	* @termios: termios structure
87	*
88	* Convert termios baud rate data into a speed. This should be called
89	* with the termios lock held if this termios is a terminal termios
90	* structure. May change the termios data. Device drivers can call this
91	* function but should use ->c_[io]speed directly as they are updated.
92	*
93	* Locking: none
94	*/
95
96	speed_t tty_termios_input_baud_rate(struct ktermios *termios)
97	{
98	#ifdef IBSHIFT
99	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
100
101	if (cbaud == B0)
102	return tty_termios_baud_rate(termios);
fefe287e	103	#ifdef BOTHER
fff0a2ca NP	104	/* Magic token for arbitrary speed via c_ispeed*/
	105	if (cbaud == BOTHER)
	106	return termios->c_ispeed;
fefe287e	107	#endif
fff0a2ca NP	108	if (cbaud & CBAUDEX) {
	109	cbaud &= ~CBAUDEX;
	110
	111	if (cbaud < 1 \|\| cbaud + 15 > n_baud_table)
	112	termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
	113	else
	114	cbaud += 15;
	115	}
	116	return baud_table[cbaud];
fefe287e	117	#else /* IBSHIFT */
fff0a2ca	118	return tty_termios_baud_rate(termios);
fefe287e	119	#endif /* IBSHIFT */
fff0a2ca NP	120	}
	121	EXPORT_SYMBOL(tty_termios_input_baud_rate);
	122
	123	/**
	124	* tty_termios_encode_baud_rate
	125	* @termios: ktermios structure holding user requested state
	126	* @ispeed: input speed
	127	* @ospeed: output speed
	128	*
	129	* Encode the speeds set into the passed termios structure. This is
	130	* used as a library helper for drivers so that they can report back
	131	* the actual speed selected when it differs from the speed requested
	132	*
	133	* For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
	134	* we need to carefully set the bits when the user does not get the
	135	* desired speed. We allow small margins and preserve as much of possible
	136	* of the input intent to keep compatibility.
	137	*
	138	* Locking: Caller should hold termios lock. This is already held
	139	* when calling this function from the driver termios handler.
	140	*
	141	* The ifdefs deal with platforms whose owners have yet to update them
	142	* and will all go away once this is done.
	143	*/
	144
	145	void tty_termios_encode_baud_rate(struct ktermios *termios,
	146	speed_t ibaud, speed_t obaud)
	147	{
	148	int i = 0;
	149	int ifound = -1, ofound = -1;
	150	int iclose = ibaud/50, oclose = obaud/50;
	151	int ibinput = 0;
	152
	153	if (obaud == 0) /* CD dropped */
	154	ibaud = 0; /* Clear ibaud to be sure */
	155
	156	termios->c_ispeed = ibaud;
	157	termios->c_ospeed = obaud;
	158
fefe287e	159	#ifdef IBSHIFT
1cee38f0 JH	160	if ((termios->c_cflag >> IBSHIFT) & CBAUD)
1cee38f0 JH	161	ibinput = 1; /* An input speed was specified */
fefe287e JH	162	#endif
fefe287e JH	163	#ifdef BOTHER
fff0a2ca NP	164	/* If the user asked for a precise weird speed give a precise weird
	165	answer. If they asked for a Bfoo speed they may have problems
	166	digesting non-exact replies so fuzz a bit */
	167
1cee38f0	168	if ((termios->c_cflag & CBAUD) == BOTHER) {
fff0a2ca	169	oclose = 0;
1cee38f0 JH	170	if (!ibinput)
	171	iclose = 0;
	172	}
fff0a2ca NP	173	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
fff0a2ca NP	174	iclose = 0;
fff0a2ca NP	175	#endif
fff0a2ca NP	176	termios->c_cflag &= ~CBAUD;
fada18c4 JH	177	#ifdef IBSHIFT
	178	termios->c_cflag &= ~(CBAUD << IBSHIFT);
	179	#endif
fff0a2ca NP	180
	181	/*
	182	* Our goal is to find a close match to the standard baud rate
	183	* returned. Walk the baud rate table and if we get a very close
	184	* match then report back the speed as a POSIX Bxxxx value by
	185	* preference
	186	*/
	187
	188	do {
	189	if (obaud - oclose <= baud_table[i] &&
	190	obaud + oclose >= baud_table[i]) {
	191	termios->c_cflag \|= baud_bits[i];
	192	ofound = i;
	193	}
	194	if (ibaud - iclose <= baud_table[i] &&
	195	ibaud + iclose >= baud_table[i]) {
	196	/* For the case input == output don't set IBAUD bits
	197	if the user didn't do so */
	198	if (ofound == i && !ibinput)
	199	ifound = i;
	200	#ifdef IBSHIFT
	201	else {
	202	ifound = i;
	203	termios->c_cflag \|= (baud_bits[i] << IBSHIFT);
	204	}
	205	#endif
	206	}
	207	} while (++i < n_baud_table);
	208
	209	/*
	210	* If we found no match then use BOTHER if provided or warn
	211	* the user their platform maintainer needs to wake up if not.
	212	*/
	213	#ifdef BOTHER
	214	if (ofound == -1)
	215	termios->c_cflag \|= BOTHER;
	216	/* Set exact input bits only if the input and output differ or the
	217	user already did */
	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
	229	* @ibaud: input baud rate
	230	* @obad: output baud rate
	231	*
	232	* Update the current termios data for the tty with the new speed
	233	* settings. The caller must hold the termios_rwsem for the tty in
	234	* question.
	235	*/
	236
	237	void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
	238	{
	239	tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
	240	}
	241	EXPORT_SYMBOL_GPL(tty_encode_baud_rate);