u-boot/drivers/serial/serial_pl01x.c
Linus Walleij 96baa4c376 serial: pl01x: drain PL01x FIFO before baudrate change
Not draining the FIFO and waiting for the UART to be non-busy
before changing baudrate results in crap characters on the
console, so let's wait for the FIFO to drain and the last
character to be clocked out before we do that.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2011-10-22 00:42:04 +02:00

251 lines
5.6 KiB
C

/*
* (C) Copyright 2000
* Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
*
* (C) Copyright 2004
* ARM Ltd.
* Philippe Robin, <philippe.robin@arm.com>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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 (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/* Simple U-Boot driver for the PrimeCell PL010/PL011 UARTs */
#include <common.h>
#include <watchdog.h>
#include <asm/io.h>
#include "serial_pl01x.h"
/*
* Integrator AP has two UARTs, we use the first one, at 38400-8-N-1
* Integrator CP has two UARTs, use the first one, at 38400-8-N-1
* Versatile PB has four UARTs.
*/
#define CONSOLE_PORT CONFIG_CONS_INDEX
static volatile unsigned char *const port[] = CONFIG_PL01x_PORTS;
#define NUM_PORTS (sizeof(port)/sizeof(port[0]))
static void pl01x_putc (int portnum, char c);
static int pl01x_getc (int portnum);
static int pl01x_tstc (int portnum);
unsigned int baudrate = CONFIG_BAUDRATE;
DECLARE_GLOBAL_DATA_PTR;
static struct pl01x_regs *pl01x_get_regs(int portnum)
{
return (struct pl01x_regs *) port[portnum];
}
#ifdef CONFIG_PL010_SERIAL
int serial_init (void)
{
struct pl01x_regs *regs = pl01x_get_regs(CONSOLE_PORT);
unsigned int divisor;
/* First, disable everything */
writel(0, &regs->pl010_cr);
/* Set baud rate */
switch (baudrate) {
case 9600:
divisor = UART_PL010_BAUD_9600;
break;
case 19200:
divisor = UART_PL010_BAUD_9600;
break;
case 38400:
divisor = UART_PL010_BAUD_38400;
break;
case 57600:
divisor = UART_PL010_BAUD_57600;
break;
case 115200:
divisor = UART_PL010_BAUD_115200;
break;
default:
divisor = UART_PL010_BAUD_38400;
}
writel((divisor & 0xf00) >> 8, &regs->pl010_lcrm);
writel(divisor & 0xff, &regs->pl010_lcrl);
/* Set the UART to be 8 bits, 1 stop bit, no parity, fifo enabled */
writel(UART_PL010_LCRH_WLEN_8 | UART_PL010_LCRH_FEN, &regs->pl010_lcrh);
/* Finally, enable the UART */
writel(UART_PL010_CR_UARTEN, &regs->pl010_cr);
return 0;
}
#endif /* CONFIG_PL010_SERIAL */
#ifdef CONFIG_PL011_SERIAL
int serial_init (void)
{
struct pl01x_regs *regs = pl01x_get_regs(CONSOLE_PORT);
unsigned int temp;
unsigned int divider;
unsigned int remainder;
unsigned int fraction;
unsigned int lcr;
#ifdef CONFIG_PL011_SERIAL_FLUSH_ON_INIT
/* Empty RX fifo if necessary */
if (readl(&regs->pl011_cr) & UART_PL011_CR_UARTEN) {
while (!(readl(&regs->fr) & UART_PL01x_FR_RXFE))
readl(&regs->dr);
}
#endif
/* First, disable everything */
writel(0, &regs->pl011_cr);
/*
* Set baud rate
*
* IBRD = UART_CLK / (16 * BAUD_RATE)
* FBRD = RND((64 * MOD(UART_CLK,(16 * BAUD_RATE))) / (16 * BAUD_RATE))
*/
temp = 16 * baudrate;
divider = CONFIG_PL011_CLOCK / temp;
remainder = CONFIG_PL011_CLOCK % temp;
temp = (8 * remainder) / baudrate;
fraction = (temp >> 1) + (temp & 1);
writel(divider, &regs->pl011_ibrd);
writel(fraction, &regs->pl011_fbrd);
/* Set the UART to be 8 bits, 1 stop bit, no parity, fifo enabled */
lcr = UART_PL011_LCRH_WLEN_8 | UART_PL011_LCRH_FEN;
writel(lcr, &regs->pl011_lcrh);
#ifdef CONFIG_PL011_SERIAL_RLCR
{
int i;
/*
* Program receive line control register after waiting
* 10 bus cycles. Delay be writing to readonly register
* 10 times
*/
for (i = 0; i < 10; i++)
writel(lcr, &regs->fr);
writel(lcr, &regs->pl011_rlcr);
}
#endif
/* Finally, enable the UART */
writel(UART_PL011_CR_UARTEN | UART_PL011_CR_TXE | UART_PL011_CR_RXE,
&regs->pl011_cr);
return 0;
}
#endif /* CONFIG_PL011_SERIAL */
void serial_putc (const char c)
{
if (c == '\n')
pl01x_putc (CONSOLE_PORT, '\r');
pl01x_putc (CONSOLE_PORT, c);
}
void serial_puts (const char *s)
{
while (*s) {
serial_putc (*s++);
}
}
int serial_getc (void)
{
return pl01x_getc (CONSOLE_PORT);
}
int serial_tstc (void)
{
return pl01x_tstc (CONSOLE_PORT);
}
void serial_setbrg (void)
{
struct pl01x_regs *regs = pl01x_get_regs(CONSOLE_PORT);
baudrate = gd->baudrate;
/*
* Flush FIFO and wait for non-busy before changing baudrate to avoid
* crap in console
*/
while (!(readl(&regs->fr) & UART_PL01x_FR_TXFE))
WATCHDOG_RESET();
while (readl(&regs->fr) & UART_PL01x_FR_BUSY)
WATCHDOG_RESET();
serial_init();
}
static void pl01x_putc (int portnum, char c)
{
struct pl01x_regs *regs = pl01x_get_regs(portnum);
/* Wait until there is space in the FIFO */
while (readl(&regs->fr) & UART_PL01x_FR_TXFF)
WATCHDOG_RESET();
/* Send the character */
writel(c, &regs->dr);
}
static int pl01x_getc (int portnum)
{
struct pl01x_regs *regs = pl01x_get_regs(portnum);
unsigned int data;
/* Wait until there is data in the FIFO */
while (readl(&regs->fr) & UART_PL01x_FR_RXFE)
WATCHDOG_RESET();
data = readl(&regs->dr);
/* Check for an error flag */
if (data & 0xFFFFFF00) {
/* Clear the error */
writel(0xFFFFFFFF, &regs->ecr);
return -1;
}
return (int) data;
}
static int pl01x_tstc (int portnum)
{
struct pl01x_regs *regs = pl01x_get_regs(portnum);
WATCHDOG_RESET();
return !(readl(&regs->fr) & UART_PL01x_FR_RXFE);
}