linux-fedora/linux-2.6-serial-460800.patch

   1 diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
   2 index 2209620..659c1bb 100644
   3 --- a/drivers/tty/serial/8250.c
   4 +++ b/drivers/tty/serial/8250.c
   5 @@ -7,6 +7,9 @@
   6   *
   7   *  Copyright (C) 2001 Russell King.
   8   *
   9 + *  2005/09/16: Enabled higher baud rates for 16C95x.
  10 + *             (Mathias Adam <a2@adamis.de>)
  11 + *
  12   * This program is free software; you can redistribute it and/or modify
  13   * it under the terms of the GNU General Public License as published by
  14   * the Free Software Foundation; either version 2 of the License, or
  15 @@ -2227,6 +2230,14 @@ static unsigned int serial8250_get_divisor(struct uart_port *port, unsigned int
  16         else if ((port->flags & UPF_MAGIC_MULTIPLIER) &&
  17                  baud == (port->uartclk/8))
  18                 quot = 0x8002;
  19 +       /*
  20 +        * For 16C950s UART_TCR is used in combination with divisor==1
  21 +        * to achieve baud rates up to baud_base*4.
  22 +        */
  23 +       else if ((port->type == PORT_16C950) &&
  24 +                baud > (port->uartclk/16))
  25 +               quot = 1;
  26 +
  27         else
  28                 quot = uart_get_divisor(port, baud);
  29
  30 @@ -2240,7 +2251,7 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
  31         struct uart_8250_port *up = (struct uart_8250_port *)port;
  32         unsigned char cval, fcr = 0;
  33         unsigned long flags;
  34 -       unsigned int baud, quot;
  35 +       unsigned int baud, quot, max_baud;
  36
  37         switch (termios->c_cflag & CSIZE) {
  38         case CS5:
  39 @@ -2272,9 +2283,10 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
  40         /*
  41          * Ask the core to calculate the divisor for us.
  42          */
  43 +       max_baud = (up->port.type == PORT_16C950 ? port->uartclk/4 : port->uartclk/16);
  44         baud = uart_get_baud_rate(port, termios, old,
  45                                   port->uartclk / 16 / 0xffff,
  46 -                                 port->uartclk / 16);
  47 +                                 max_baud);
  48         quot = serial8250_get_divisor(port, baud);
  49
  50         /*
  51 @@ -2311,6 +2323,19 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
  52         spin_lock_irqsave(&up->port.lock, flags);
  53
  54         /*
  55 +        * 16C950 supports additional prescaler ratios between 1:16 and 1:4
  56 +        * thus increasing max baud rate to uartclk/4.
  57 +        */
  58 +       if (up->port.type == PORT_16C950) {
  59 +               if (baud == port->uartclk/4)
  60 +                       serial_icr_write(up, UART_TCR, 0x4);
  61 +               else if (baud == port->uartclk/8)
  62 +                       serial_icr_write(up, UART_TCR, 0x8);
  63 +               else
  64 +                       serial_icr_write(up, UART_TCR, 0);
  65 +       }
  66 +
  67 +       /*
  68          * Update the per-port timeout.
  69          */
  70         uart_update_timeout(port, termios->c_cflag, baud);