[SERIAL] uart_get_divisor() and uart_get_baud_rate() takes termios.

Currently, uart_get_divisor() and uart_get_baud_rate() take a tty
structure.  We really want them to take a termios structure so we
can avoid passing a tty structure all  the way down to the low level
drivers.

In order to do this, we need to be able to convert a termios
structure to a numeric baud rate - we provide tty_termios_baud_rate() in
tty_io.c for this purpose.  It performs a subset of the
tty_get_baud_rate() functionality, but without any "alt_speed"
kludge.

We finally export uart_get_baud_rate() and uart_get_divisor() to for
low level drivers to use.  We now have all the functions in place
to support ports which want to have access to the real baud rate
rather than a divisor value.

drivers/char/tty_io.c

@@ -372,6 +372,8 @@ int tty_check_change(struct tty_struct * tty)
 	return -ERESTARTSYS;
 }
 
+EXPORT_SYMBOL(tty_check_change);
+
 static ssize_t hung_up_tty_read(struct file * file, char * buf,
 				size_t count, loff_t *ppos)
 {
@@ -540,6 +542,8 @@ void tty_hangup(struct tty_struct * tty)
 	schedule_work(&tty->hangup_work);
 }
 
+EXPORT_SYMBOL(tty_hangup);
+
 void tty_vhangup(struct tty_struct * tty)
 {
 #ifdef TTY_DEBUG_HANGUP
@@ -556,6 +560,8 @@ int tty_hung_up_p(struct file * filp)
 	return (filp->f_op == &hung_up_tty_fops);
 }
 
+EXPORT_SYMBOL(tty_hung_up_p);
+
 /*
  * This function is typically called only by the session leader, when
  * it wants to disassociate itself from its controlling tty.
@@ -1886,6 +1892,8 @@ void do_SAK(struct tty_struct *tty)
 	schedule_work(&tty->SAK_work);
 }
 
+EXPORT_SYMBOL(do_SAK);
+
 /*
  * This routine is called out of the software interrupt to flush data
  * from the flip buffer to the line discipline.
@@ -1946,34 +1954,44 @@ static int baud_table[] = {
 #endif
 };
 
-static int n_baud_table = sizeof(baud_table)/sizeof(int);
+static int n_baud_table = ARRAY_SIZE(baud_table);
 
-int tty_get_baud_rate(struct tty_struct *tty)
+int tty_termios_baud_rate(struct termios *termios)
 {
-	unsigned int cflag, i;
+	unsigned int cbaud = termios->c_cflag & CBAUD;
 
-	cflag = tty->termios->c_cflag;
+	if (cbaud & CBAUDEX) {
+		cbaud &= ~CBAUDEX;
 
-	i = cflag & CBAUD;
-	if (i & CBAUDEX) {
-		i &= ~CBAUDEX;
-		if (i < 1 || i+15 >= n_baud_table) 
-			tty->termios->c_cflag &= ~CBAUDEX;
+		if (cbaud < 1 || cbaud + 15 > n_baud_table)
+			termios->c_cflag &= ~CBAUDEX;
 		else
-			i += 15;
+			cbaud += 15;
 	}
-	if (i==15 && tty->alt_speed) {
+
+	return baud_table[cbaud];
+}
+
+EXPORT_SYMBOL(tty_termios_baud_rate);
+
+int tty_get_baud_rate(struct tty_struct *tty)
+{
+	int baud = tty_termios_baud_rate(tty->termios);
+
+	if (baud == 38400 && tty->alt_speed) {
 		if (!tty->warned) {
 			printk(KERN_WARNING "Use of setserial/setrocket to "
 					    "set SPD_* flags is deprecated\n");
 			tty->warned = 1;
 		}
-		return(tty->alt_speed);
+		baud = tty->alt_speed;
 	}
 	
-	return baud_table[i];
+	return baud;
 }
 
+EXPORT_SYMBOL(tty_get_baud_rate);
+
 void tty_flip_buffer_push(struct tty_struct *tty)
 {
 	if (tty->low_latency)

drivers/serial/core.c

@@ -313,16 +313,16 @@ EXPORT_SYMBOL(uart_update_timeout);
 /**
  *	uart_get_baud_rate - return baud rate for a particular port
  *	@port: uart_port structure describing the port in question.
- *	@tty: the tty structure corresponding to this port
+ *	@termios: desired termios settings.
  *
  *	Decode the termios structure into a numeric baud rate,
  *	taking account of the magic 38400 baud rate (with spd_*
  *	flags), and mapping the %B0 rate to 9600 baud.
  */
-static unsigned int
-uart_get_baud_rate(struct uart_port *port, struct tty_struct *tty)
+unsigned int
+uart_get_baud_rate(struct uart_port *port, struct termios *termios)
 {
-	unsigned int baud = tty_get_baud_rate(tty);
+	unsigned int baud = tty_termios_baud_rate(termios);
 
 	/*
 	 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
@@ -350,8 +350,10 @@ uart_get_baud_rate(struct uart_port *port, struct tty_struct *tty)
 	return baud;
 }
 
-static inline
-unsigned int uart_calculate_quot(struct uart_port *port, unsigned int baud)
+EXPORT_SYMBOL(uart_get_baud_rate);
+
+static inline unsigned int
+uart_calculate_quot(struct uart_port *port, unsigned int baud)
 {
 	unsigned int quot;
 
@@ -369,7 +371,7 @@ unsigned int uart_calculate_quot(struct uart_port *port, unsigned int baud)
 /**
  *	uart_get_divisor - return uart clock divisor
  *	@port: uart_port structure describing the port.
- *	@tty: desired tty settings
+ *	@termios: desired termios settings
  *	@old_termios: the original port settings, or NULL
  *
  *	Calculate the uart clock divisor for the port.  If the
@@ -381,8 +383,8 @@ unsigned int uart_calculate_quot(struct uart_port *port, unsigned int baud)
  *
  *	If 9600 baud fails, we return a zero divisor.
  */
-static unsigned int
-uart_get_divisor(struct uart_port *port, struct tty_struct *tty,
+unsigned int
+uart_get_divisor(struct uart_port *port, struct termios *termios,
 		 struct termios *old_termios)
 {
 	unsigned int quot, try;
@@ -391,7 +393,7 @@ uart_get_divisor(struct uart_port *port, struct tty_struct *tty,
 		unsigned int baud;
 
 		/* Determine divisor based on baud rate */
-		baud = uart_get_baud_rate(port, tty);
+		baud = uart_get_baud_rate(port, termios);
 		quot = uart_calculate_quot(port, baud);
 		if (quot)
 			break;
@@ -400,10 +402,9 @@ uart_get_divisor(struct uart_port *port, struct tty_struct *tty,
 		 * Oops, the quotient was zero.  Try again with
 		 * the old baud rate if possible.
 		 */
-		tty->termios->c_cflag &= ~CBAUD;
+		termios->c_cflag &= ~CBAUD;
 		if (old_termios) {
-			tty->termios->c_cflag |=
-				 (old_termios->c_cflag & CBAUD);
+			termios->c_cflag |= old_termios->c_cflag & CBAUD;
 			old_termios = NULL;
 			continue;
 		}
@@ -412,43 +413,48 @@ uart_get_divisor(struct uart_port *port, struct tty_struct *tty,
 		 * As a last resort, if the quotient is zero,
 		 * default to 9600 bps
 		 */
-		tty->termios->c_cflag |= B9600;
+		termios->c_cflag |= B9600;
 	}
 
 	return quot;
 }
 
+EXPORT_SYMBOL(uart_get_divisor);
+
 static void
 uart_change_speed(struct uart_info *info, struct termios *old_termios)
 {
+	struct tty_struct *tty = info->tty;
 	struct uart_port *port = info->port;
-	unsigned int quot, cflag, bits, try;
+	struct termios *termios;
+	unsigned int quot;
 
 	/*
 	 * If we have no tty, termios, or the port does not exist,
 	 * then we can't set the parameters for this port.
 	 */
-	if (!info->tty || !info->tty->termios || port->type == PORT_UNKNOWN)
+	if (!tty || !tty->termios || port->type == PORT_UNKNOWN)
 		return;
 
+	termios = tty->termios;
+
 	/*
 	 * Set flags based on termios cflag
 	 */
-	cflag = info->tty->termios->c_cflag;
-
-	quot = uart_get_divisor(port, tty, old_termios);
-	uart_update_timeout(port, cflag, quot);
-
-	if (cflag & CRTSCTS)
+	if (termios->c_cflag & CRTSCTS)
 		info->flags |= UIF_CTS_FLOW;
 	else
 		info->flags &= ~UIF_CTS_FLOW;
-	if (cflag & CLOCAL)
+
+	if (termios->c_cflag & CLOCAL)
 		info->flags &= ~UIF_CHECK_CD;
 	else
 		info->flags |= UIF_CHECK_CD;
 
-	port->ops->change_speed(port, cflag, info->tty->termios->c_iflag, quot);
+	quot = uart_get_divisor(port, termios, old_termios);
+	uart_update_timeout(port, termios->c_cflag, quot);
+
+	port->ops->change_speed(port, termios->c_cflag, termios->c_iflag, quot);
 }
 
 static inline void

include/linux/tty.h

@@ -397,6 +397,7 @@ extern void do_SAK(struct tty_struct *tty);
 extern void disassociate_ctty(int priv);
 extern void tty_flip_buffer_push(struct tty_struct *tty);
 extern int tty_get_baud_rate(struct tty_struct *tty);
+extern int tty_termios_baud_rate(struct termios *termios);
 
 /* n_tty.c */
 extern struct tty_ldisc tty_ldisc_N_TTY;

kernel/ksyms.c

@@ -353,13 +353,8 @@ EXPORT_SYMBOL(generic_file_writev);
 EXPORT_SYMBOL(iov_shorten);
 
 /* tty routines */
-EXPORT_SYMBOL(tty_hangup);
 EXPORT_SYMBOL(tty_wait_until_sent);
-EXPORT_SYMBOL(tty_check_change);
-EXPORT_SYMBOL(tty_hung_up_p);
 EXPORT_SYMBOL(tty_flip_buffer_push);
-EXPORT_SYMBOL(tty_get_baud_rate);
-EXPORT_SYMBOL(do_SAK);
 
 /* filesystem registration */
 EXPORT_SYMBOL(register_filesystem);