Allow uart drivers to calculate divisors differently.

In order to deal with the weird and wonderful ways of obtaining a uart clock
which a lot of the high-speed hacks for 16550-based chips seem to have, we need
to make uart_update_timeout() and uart_get_divisor() take the desired baud rate
as their arguments, instead of termios or divisor as before. The main reason for the
change to uart_get_divisor(), requiring a call to uart_get_baud_rate() before it, is
so that the drivers actually _have_ the baud rate in order that they can pass it to
uart_update_timeout().

drivers/serial/21285.c

@@ -237,7 +237,7 @@ serial21285_set_termios(struct uart_port *port, struct termios *termios,
 			struct termios *old)
 {
 	unsigned long flags;
-	unsigned int quot, h_lcr;
+	unsigned int baud, quot, h_lcr;
 
 	/*
 	 * We don't support modem control lines.
@@ -253,7 +253,8 @@ serial21285_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -286,7 +287,7 @@ serial21285_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	/*
 	 * Which character status flags are we interested in?

drivers/serial/8250.c

@@ -1325,7 +1325,7 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 	unsigned char cval, fcr = 0;
 	unsigned long flags;
-	unsigned int quot;
+	unsigned int baud, quot;
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -1357,7 +1357,8 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	/*
 	 * Work around a bug in the Oxford Semiconductor 952 rev B
@@ -1369,7 +1370,7 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
 		quot ++;
 
 	if (uart_config[up->port.type].flags & UART_USE_FIFO) {
-		if ((up->port.uartclk / quot) < (2400 * 16))
+		if (baud < 2400)
 			fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
 #ifdef CONFIG_SERIAL_8250_RSA
 		else if (up->port.type == PORT_RSA)
@@ -1390,7 +1391,7 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
 	if (termios->c_iflag & INPCK)

drivers/serial/amba.c

@@ -408,12 +408,13 @@ ambauart_set_termios(struct uart_port *port, struct termios *termios,
 {
 	unsigned int lcr_h, old_cr;
 	unsigned long flags;
-	unsigned int quot;
+	unsigned int baud, quot;
 
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -444,7 +445,7 @@ ambauart_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	port->read_status_mask = AMBA_UARTRSR_OE;
 	if (termios->c_iflag & INPCK)

drivers/serial/anakin.c

@@ -287,7 +287,7 @@ anakin_set_termios(struct uart_port *port, struct termios *termios,
 		   struct termios *old)
 {
 	unsigned long flags;
-	unsigned int quot;
+	unsigned int baud, quot;
 
 	/*
 	 * We don't support parity, stop bits, or anything other
@@ -304,11 +304,12 @@ anakin_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	spin_lock_irqsave(&port->lock, flags);
 
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	while (!(anakin_in(port, 0x10) & TXEMPTY))
 		barrier();

drivers/serial/clps711x.c

@@ -320,7 +320,7 @@ static void
 clps711xuart_set_termios(struct uart_port *port, struct termios *termios,
 			 struct termios *old)
 {
-	unsigned int ubrlcr, quot;
+	unsigned int ubrlcr, baud, quot;
 	unsigned long flags;
 
 	/*
@@ -331,7 +331,8 @@ clps711xuart_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -362,7 +363,7 @@ clps711xuart_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	port->read_status_mask = UARTDR_OVERR;
 	if (termios->c_iflag & INPCK)

drivers/serial/core.c

@@ -271,7 +271,7 @@ static void uart_shutdown(struct uart_info *info)
  */
 void
 uart_update_timeout(struct uart_port *port, unsigned int cflag,
-		    unsigned int quot)
+		    unsigned int baud)
 {
 	unsigned int bits;
 
@@ -305,7 +305,7 @@ uart_update_timeout(struct uart_port *port, unsigned int cflag,
 	 * Figure the timeout to send the above number of bits.
 	 * Add .02 seconds of slop
 	 */
-	port->timeout = (HZ * bits) / (port->uartclk / (16 * quot)) + HZ/50;
+	port->timeout = (HZ * bits) / baud + HZ/50;
 }
 
 EXPORT_SYMBOL(uart_update_timeout);
@@ -321,6 +321,12 @@ EXPORT_SYMBOL(uart_update_timeout);
  *	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.
+ *
+ *	If the new baud rate is invalid, try the old termios setting.
+ *	If it's still invalid, we try 9600 baud.
+ *
+ *	Update the @termios structure to reflect the baud rate
+ *	we're actually going to be using.
  */
 unsigned int
 uart_get_baud_rate(struct uart_port *port, struct termios *termios,
@@ -383,26 +389,14 @@ EXPORT_SYMBOL(uart_get_baud_rate);
 /**
  *	uart_get_divisor - return uart clock divisor
  *	@port: uart_port structure describing the port.
- *	@termios: desired termios settings
- *	@old_termios: the original port settings, or NULL
- *
- *	Calculate the uart clock divisor for the port.  If the
- *	divisor is invalid, try the old termios setting.  If
- *	the divisor is still invalid, we try 9600 baud.
+ *	@baud: desired baud rate
  *
- *	Update the @termios structure to reflect the baud rate
- *	we're actually going to be using.
- *
- *	If 9600 baud fails, we return a zero divisor.
+ *	Calculate the uart clock divisor for the port.
  */
 unsigned int
-uart_get_divisor(struct uart_port *port, struct termios *termios,
-		 struct termios *old_termios)
+uart_get_divisor(struct uart_port *port, unsigned int baud)
 {
-	unsigned int quot, baud, max = port->uartclk / 16;
-
-	/* Determine divisor based on baud rate */
-	baud = uart_get_baud_rate(port, termios, old_termios, 0, max);
+	unsigned int quot;
 
 	/*
 	 * Old custom speed handling.

drivers/serial/sa1100.c

@@ -441,7 +441,7 @@ sa1100_set_termios(struct uart_port *port, struct termios *termios,
 {
 	struct sa1100_port *sport = (struct sa1100_port *)port;
 	unsigned long flags;
-	unsigned int utcr0, old_utcr3, quot;
+	unsigned int utcr0, old_utcr3, baud, quot;
 	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
 
 	/*
@@ -470,7 +470,8 @@ sa1100_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 
@@ -507,7 +508,7 @@ sa1100_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	/*
 	 * disable interrupts and drain transmitter

drivers/serial/sunsu.c

@@ -853,7 +853,7 @@ sunsu_change_speed(struct uart_port *port, unsigned int cflag,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, cflag, quot);
+	uart_update_timeout(port, cflag, (port->uartclk / (16 * quot)));
 
 	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
 	if (iflag & INPCK)
@@ -920,12 +920,13 @@ static void
 sunsu_set_termios(struct uart_port *port, struct termios *termios,
 		  struct termios *old)
 {
-	unsigned int quot;
+	unsigned int baud, quot;
 
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	sunsu_change_speed(port, termios->c_cflag, termios->c_iflag, quot);
 }

drivers/serial/uart00.c

@@ -317,7 +317,7 @@ static void
 uart00_set_termios(struct uart_port *port, struct termios *termios,
 		   struct termios *old)
 {
-	unsigned int uart_mc, old_ies, quot;
+	unsigned int uart_mc, old_ies, baud, quot;
 	unsigned long flags;
 
 	/*
@@ -328,7 +328,8 @@ uart00_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Ask the core to calculate the divisor for us.
 	 */
-	quot = uart_get_divisor(port, termios, old);
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
 
 	/* byte size and parity */
 	switch (termios->c_cflag & CSIZE) {
@@ -358,7 +359,7 @@ uart00_set_termios(struct uart_port *port, struct termios *termios,
 	/*
 	 * Update the per-port timeout.
 	 */
-	uart_update_timeout(port, termios->c_cflag, quot);
+	uart_update_timeout(port, termios->c_cflag, baud);
 
 	port->read_status_mask = UART_RDS_OE_MSK;
 	if (termios->c_iflag & INPCK)

include/linux/serial_core.h

@@ -279,12 +279,11 @@ void uart_write_wakeup(struct uart_port *port);
  * Baud rate helpers.
  */
 void uart_update_timeout(struct uart_port *port, unsigned int cflag,
-			 unsigned int quot);
+			 unsigned int baud);
 unsigned int uart_get_baud_rate(struct uart_port *port, struct termios *termios,
 				struct termios *old, unsigned int min,
 				unsigned int max);
-unsigned int uart_get_divisor(struct uart_port *port, struct termios *termios,
-			      struct termios *old_termios);
+unsigned int uart_get_divisor(struct uart_port *port, unsigned int baud);
 
 /*
  * Console helpers.