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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2003 Eric Biederman
* Copyright (C) 2006-2010 coresystems GmbH
*
* 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; version 2 of the License.
*
* 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.
*/
#include <arch/io.h>
#include <console/uart.h>
#include <device/device.h>
#include <delay.h>
#include <stdint.h>
#include "uart8250reg.h"
/* Should support 8250, 16450, 16550, 16550A type UARTs */
/* Expected character delay at 1200bps is 9ms for a working UART
* and no flow-control. Assume UART as stuck if shift register
* or FIFO takes more than 50ms per character to appear empty.
*/
#define SINGLE_CHAR_TIMEOUT (50 * 1000)
#define FIFO_TIMEOUT (16 * SINGLE_CHAR_TIMEOUT)
static uint8_t uart8250_read(void *base, uint8_t reg)
{
return read8(base + reg);
}
static void uart8250_write(void *base, uint8_t reg, uint8_t data)
{
write8(base + reg, data);
}
static int uart8250_mem_can_tx_byte(void *base)
{
return uart8250_read(base, UART8250_LSR) & UART8250_LSR_THRE;
}
static void uart8250_mem_tx_byte(void *base, unsigned char data)
{
unsigned long int i = SINGLE_CHAR_TIMEOUT;
while(i-- && !uart8250_mem_can_tx_byte(base))
udelay(1);
uart8250_write(base, UART8250_TBR, data);
}
static void uart8250_mem_tx_flush(void *base)
{
unsigned long int i = FIFO_TIMEOUT;
while(i-- && !(uart8250_read(base, UART8250_LSR) & UART8250_LSR_TEMT))
udelay(1);
}
static int uart8250_mem_can_rx_byte(void *base)
{
return uart8250_read(base, UART8250_LSR) & UART8250_LSR_DR;
}
static unsigned char uart8250_mem_rx_byte(void *base)
{
unsigned long int i = SINGLE_CHAR_TIMEOUT;
while(i-- && !uart8250_mem_can_rx_byte(base))
udelay(1);
if (i)
return uart8250_read(base, UART8250_RBR);
else
return 0x0;
}
static void uart8250_mem_init(void *base, unsigned divisor)
{
/* Disable interrupts */
uart8250_write(base, UART8250_IER, 0x0);
/* Enable FIFOs */
uart8250_write(base, UART8250_FCR, UART8250_FCR_FIFO_EN);
/* Assert DTR and RTS so the other end is happy */
uart8250_write(base, UART8250_MCR, UART8250_MCR_DTR | UART8250_MCR_RTS);
/* DLAB on */
uart8250_write(base, UART8250_LCR, UART8250_LCR_DLAB | CONFIG_TTYS0_LCS);
uart8250_write(base, UART8250_DLL, divisor & 0xFF);
uart8250_write(base, UART8250_DLM, (divisor >> 8) & 0xFF);
/* Set to 3 for 8N1 */
uart8250_write(base, UART8250_LCR, CONFIG_TTYS0_LCS);
}
void uart_init(int idx)
{
void *base = uart_platform_baseptr(idx);
if (!base)
return;
unsigned int div;
div = uart_baudrate_divisor(default_baudrate(), uart_platform_refclk(), 16);
uart8250_mem_init(base, div);
}
void uart_tx_byte(int idx, unsigned char data)
{
void *base = uart_platform_baseptr(idx);
if (!base)
return;
uart8250_mem_tx_byte(base, data);
}
unsigned char uart_rx_byte(int idx)
{
void *base = uart_platform_baseptr(idx);
if (!base)
return 0xff;
return uart8250_mem_rx_byte(base);
}
void uart_tx_flush(int idx)
{
void *base = uart_platform_baseptr(idx);
if (!base)
return;
uart8250_mem_tx_flush(base);
}
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