Merge to Fedora kernel-2.6.17-1.2187_FC5 patched with stable patch-2.6.17.13-vs2...

[linux-2.6.git] / drivers / serial / 8250.c

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index fbb53ad..9685977 100644 (file)
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -7,6 +7,9 @@
  *
  *  Copyright (C) 2001 Russell King.
  *
+ *  2005/09/16: Enabled higher baud rates for 16C95x.
+ *             (Mathias Adam <a2@adamis.de>)
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
@@ -1745,6 +1748,14 @@ static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int
        else if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
                 baud == (port->uartclk/8))
                quot = 0x8002;
+       /*
+        * For 16C950s UART_TCR is used in combination with divisor==1
+        * to achieve baud rates up to baud_base*4.
+        */
+       else if ((port->type == PORT_16C950) &&
+                baud > (port->uartclk/16))
+               quot = 1;
+
        else
                quot = uart_get_divisor(port, baud);
 
@@ -1758,7 +1769,7 @@ 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 baud, quot;
+       unsigned int baud, quot, max_baud;
 
        switch (termios->c_cflag & CSIZE) {
        case CS5:
@@ -1790,7 +1801,8 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
        /*
         * Ask the core to calculate the divisor for us.
         */
-       baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+       max_baud = (up->port.type == PORT_16C950 ? port->uartclk/4 : port->uartclk/16);
+       baud = uart_get_baud_rate(port, termios, old, 0, max_baud); 
        quot = serial8250_get_divisor(port, baud);
 
        /*
@@ -1826,6 +1838,19 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
         */
        spin_lock_irqsave(&up->port.lock, flags);
 
+       /* 
+        * 16C950 supports additional prescaler ratios between 1:16 and 1:4
+        * thus increasing max baud rate to uartclk/4.
+        */
+       if (up->port.type == PORT_16C950) {
+               if (baud == port->uartclk/4)
+                       serial_icr_write(up, UART_TCR, 0x4);
+               else if (baud == port->uartclk/8)
+                       serial_icr_write(up, UART_TCR, 0x8);
+               else
+                       serial_icr_write(up, UART_TCR, 0);
+       }
+       
        /*
         * Update the per-port timeout.
         */
@@ -2243,10 +2268,14 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
 
        touch_nmi_watchdog();
 
-       if (oops_in_progress) {
-               locked = spin_trylock_irqsave(&up->port.lock, flags);
+       local_irq_save(flags);
+       if (up->port.sysrq) {
+               /* serial8250_handle_port() already took the lock */
+               locked = 0;
+       } else if (oops_in_progress) {
+               locked = spin_trylock(&up->port.lock);
        } else
-               spin_lock_irqsave(&up->port.lock, flags);
+               spin_lock(&up->port.lock);
 
        /*
         *      First save the IER then disable the interrupts
@@ -2268,7 +2297,8 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
        serial_out(up, UART_IER, ier);
 
        if (locked)
-               spin_unlock_irqrestore(&up->port.lock, flags);
+               spin_unlock(&up->port.lock);
+       local_irq_restore(flags);
 }
 
 static int serial8250_console_setup(struct console *co, char *options)