linux/drivers/tty/tty_baudrate.c

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tty: add SPDX identifiers to all remaining files in drivers/tty/ It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the drivers/tty files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Jiri Slaby <jslaby@suse.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: David Sterba <dsterba@suse.com> Cc: James Hogan <jhogan@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Eric Anholt <eric@anholt.net> Cc: Stefan Wahren <stefan.wahren@i2se.com> Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: Ray Jui <rjui@broadcom.com> Cc: Scott Branden <sbranden@broadcom.com> Cc: bcm-kernel-feedback-list@broadcom.com Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Joachim Eastwood <manabian@gmail.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Tobias Klauser <tklauser@distanz.ch> Cc: Russell King <linux@armlinux.org.uk> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Richard Genoud <richard.genoud@gmail.com> Cc: Alexander Shiyan <shc_work@mail.ru> Cc: Baruch Siach <baruch@tkos.co.il> Cc: "Maciej W. Rozycki" <macro@linux-mips.org> Cc: "Uwe Kleine-König" <kernel@pengutronix.de> Cc: Pat Gefre <pfg@sgi.com> Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Vladimir Zapolskiy <vz@mleia.com> Cc: Sylvain Lemieux <slemieux.tyco@gmail.com> Cc: Carlo Caione <carlo@caione.org> Cc: Kevin Hilman <khilman@baylibre.com> Cc: Liviu Dudau <liviu.dudau@arm.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Andy Gross <andy.gross@linaro.org> Cc: David Brown <david.brown@linaro.org> Cc: "Andreas Färber" <afaerber@suse.de> Cc: Kevin Cernekee <cernekee@gmail.com> Cc: Laxman Dewangan <ldewangan@nvidia.com> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: Jonathan Hunter <jonathanh@nvidia.com> Cc: Barry Song <baohua@kernel.org> Cc: Patrice Chotard <patrice.chotard@st.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Alexandre Torgue <alexandre.torgue@st.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Peter Korsgaard <jacmet@sunsite.dk> Cc: Timur Tabi <timur@tabi.org> Cc: Tony Prisk <linux@prisktech.co.nz> Cc: Michal Simek <michal.simek@xilinx.com> Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Jiri Slaby <jslaby@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 01:11:51 +08:00
// 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);