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+/*
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+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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+ */
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+
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+#include <linux/types.h>
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+#include <linux/kernel.h>
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+#include <linux/termios.h>
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+#include <linux/tty.h>
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+#include <linux/export.h>
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+
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+
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+/*
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+ * Routine which returns the baud rate of the tty
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+ *
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+ * Note that the baud_table needs to be kept in sync with the
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+ * include/asm/termbits.h file.
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+ */
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+static const speed_t baud_table[] = {
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+ 0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
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+ 9600, 19200, 38400, 57600, 115200, 230400, 460800,
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+#ifdef __sparc__
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+ 76800, 153600, 307200, 614400, 921600
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+#else
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+ 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
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+ 2500000, 3000000, 3500000, 4000000
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+#endif
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+};
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+
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+#ifndef __sparc__
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+static const tcflag_t baud_bits[] = {
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+ B0, B50, B75, B110, B134, B150, B200, B300, B600,
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+ B1200, B1800, B2400, B4800, B9600, B19200, B38400,
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+ B57600, B115200, B230400, B460800, B500000, B576000,
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+ B921600, B1000000, B1152000, B1500000, B2000000, B2500000,
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+ B3000000, B3500000, B4000000
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+};
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+#else
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+static const tcflag_t baud_bits[] = {
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+ B0, B50, B75, B110, B134, B150, B200, B300, B600,
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+ B1200, B1800, B2400, B4800, B9600, B19200, B38400,
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+ B57600, B115200, B230400, B460800, B76800, B153600,
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+ B307200, B614400, B921600
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+};
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+#endif
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+
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+static int n_baud_table = ARRAY_SIZE(baud_table);
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+
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+/**
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+ * tty_termios_baud_rate
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+ * @termios: termios structure
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+ *
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+ * Convert termios baud rate data into a speed. This should be called
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+ * with the termios lock held if this termios is a terminal termios
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+ * structure. May change the termios data. Device drivers can call this
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+ * function but should use ->c_[io]speed directly as they are updated.
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+ *
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+ * Locking: none
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+ */
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+
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+speed_t tty_termios_baud_rate(struct ktermios *termios)
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+{
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+ unsigned int cbaud;
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+
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+ cbaud = termios->c_cflag & CBAUD;
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+
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+#ifdef BOTHER
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+ /* Magic token for arbitrary speed via c_ispeed/c_ospeed */
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+ if (cbaud == BOTHER)
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+ return termios->c_ospeed;
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+#endif
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+ if (cbaud & CBAUDEX) {
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+ cbaud &= ~CBAUDEX;
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+
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+ if (cbaud < 1 || cbaud + 15 > n_baud_table)
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+ termios->c_cflag &= ~CBAUDEX;
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+ else
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+ cbaud += 15;
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+ }
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+ return baud_table[cbaud];
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+}
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+EXPORT_SYMBOL(tty_termios_baud_rate);
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+
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+/**
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+ * tty_termios_input_baud_rate
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+ * @termios: termios structure
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+ *
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+ * Convert termios baud rate data into a speed. This should be called
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+ * with the termios lock held if this termios is a terminal termios
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+ * structure. May change the termios data. Device drivers can call this
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+ * function but should use ->c_[io]speed directly as they are updated.
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+ *
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+ * Locking: none
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+ */
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+
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+speed_t tty_termios_input_baud_rate(struct ktermios *termios)
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+{
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+#ifdef IBSHIFT
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+ unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
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+
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+ if (cbaud == B0)
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+ return tty_termios_baud_rate(termios);
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+
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+ /* Magic token for arbitrary speed via c_ispeed*/
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+ if (cbaud == BOTHER)
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+ return termios->c_ispeed;
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+
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+ if (cbaud & CBAUDEX) {
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+ cbaud &= ~CBAUDEX;
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+
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+ if (cbaud < 1 || cbaud + 15 > n_baud_table)
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+ termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
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+ else
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+ cbaud += 15;
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+ }
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+ return baud_table[cbaud];
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+#else
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+ return tty_termios_baud_rate(termios);
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+#endif
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+}
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+EXPORT_SYMBOL(tty_termios_input_baud_rate);
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+
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+/**
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+ * tty_termios_encode_baud_rate
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+ * @termios: ktermios structure holding user requested state
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+ * @ispeed: input speed
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+ * @ospeed: output speed
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+ *
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+ * Encode the speeds set into the passed termios structure. This is
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+ * used as a library helper for drivers so that they can report back
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+ * the actual speed selected when it differs from the speed requested
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+ *
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+ * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
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+ * we need to carefully set the bits when the user does not get the
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+ * desired speed. We allow small margins and preserve as much of possible
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+ * of the input intent to keep compatibility.
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+ *
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+ * Locking: Caller should hold termios lock. This is already held
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+ * when calling this function from the driver termios handler.
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+ *
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+ * The ifdefs deal with platforms whose owners have yet to update them
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+ * and will all go away once this is done.
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+ */
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+
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+void tty_termios_encode_baud_rate(struct ktermios *termios,
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+ speed_t ibaud, speed_t obaud)
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+{
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+ int i = 0;
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+ int ifound = -1, ofound = -1;
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+ int iclose = ibaud/50, oclose = obaud/50;
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+ int ibinput = 0;
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+
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+ if (obaud == 0) /* CD dropped */
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+ ibaud = 0; /* Clear ibaud to be sure */
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+
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+ termios->c_ispeed = ibaud;
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+ termios->c_ospeed = obaud;
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+
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+#ifdef BOTHER
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+ /* If the user asked for a precise weird speed give a precise weird
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+ answer. If they asked for a Bfoo speed they may have problems
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+ digesting non-exact replies so fuzz a bit */
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+
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+ if ((termios->c_cflag & CBAUD) == BOTHER)
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+ oclose = 0;
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+ if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
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+ iclose = 0;
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+ if ((termios->c_cflag >> IBSHIFT) & CBAUD)
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+ ibinput = 1; /* An input speed was specified */
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+#endif
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+ termios->c_cflag &= ~CBAUD;
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+
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+ /*
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+ * Our goal is to find a close match to the standard baud rate
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+ * returned. Walk the baud rate table and if we get a very close
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+ * match then report back the speed as a POSIX Bxxxx value by
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+ * preference
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+ */
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+
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+ do {
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+ if (obaud - oclose <= baud_table[i] &&
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+ obaud + oclose >= baud_table[i]) {
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+ termios->c_cflag |= baud_bits[i];
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+ ofound = i;
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+ }
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+ if (ibaud - iclose <= baud_table[i] &&
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+ ibaud + iclose >= baud_table[i]) {
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+ /* For the case input == output don't set IBAUD bits
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+ if the user didn't do so */
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+ if (ofound == i && !ibinput)
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+ ifound = i;
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+#ifdef IBSHIFT
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+ else {
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+ ifound = i;
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+ termios->c_cflag |= (baud_bits[i] << IBSHIFT);
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+ }
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+#endif
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+ }
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+ } while (++i < n_baud_table);
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+
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+ /*
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+ * If we found no match then use BOTHER if provided or warn
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+ * the user their platform maintainer needs to wake up if not.
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+ */
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+#ifdef BOTHER
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+ if (ofound == -1)
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+ termios->c_cflag |= BOTHER;
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+ /* Set exact input bits only if the input and output differ or the
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+ user already did */
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+ if (ifound == -1 && (ibaud != obaud || ibinput))
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+ termios->c_cflag |= (BOTHER << IBSHIFT);
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+#else
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+ if (ifound == -1 || ofound == -1)
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+ pr_warn_once("tty: Unable to return correct speed data as your architecture needs updating.\n");
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+#endif
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+}
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+EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);
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+
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+/**
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+ * tty_encode_baud_rate - set baud rate of the tty
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+ * @ibaud: input baud rate
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+ * @obad: output baud rate
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+ *
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+ * Update the current termios data for the tty with the new speed
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+ * settings. The caller must hold the termios_rwsem for the tty in
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+ * question.
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+ */
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+
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+void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
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+{
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+ tty_termios_encode_baud_rate(&tty->termios, ibaud, obaud);
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+}
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+EXPORT_SYMBOL_GPL(tty_encode_baud_rate);
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Nicolas Pitre