*
* 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
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);
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:
/*
* 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);
/*
*/
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.
*/
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
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)