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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2000 Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
* Copyright (C) Broadcom Corporation
* Copyright (C) 2015 Google Inc.
*
* 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.
*/
#include <arch/io.h>
#include <boot/coreboot_tables.h>
#include <console/console.h> /* for __console definition */
#include <console/uart.h>
#include <delay.h>
#include <soc/ns16550.h>
#define SYS_NS16550_CLK 100000000
#define SYS_NS16550_BAUDRATE 115200
#define MODE_X_DIV 16
#define SINGLE_CHAR_TIMEOUT (50 * 1000)
static struct ns16550 * const regs =
(void *)CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
static int calc_divisor(void)
{
/* Compute divisor value. Normally, we should simply return:
* ns16550_clk / MODE_X_DIV / baudrate
* but we need to round that value by adding 0.5.
* Rounding is especially important at high baud rates.
*/
int div = MODE_X_DIV * SYS_NS16550_BAUDRATE;
return (SYS_NS16550_CLK + div / 2) / div;
}
static void ns16550_init(void)
{
int baud_divisor = calc_divisor();
while (!(read32(®s->lsr) & UART_LSR_TEMT))
;
write32(®s->ier, 0);
write32(®s->lcr, UART_LCR_BKSE | UART_LCR_8N1);
write32(®s->dll, 0);
write32(®s->dlm, 0);
write32(®s->lcr, UART_LCR_8N1);
write32(®s->mcr, UART_MCR_DTR | UART_MCR_RTS);
/* clear & enable FIFOs */
write32(®s->fcr, UART_FCR_FIFO_EN | UART_FCR_RXSR | UART_FCR_TXSR);
write32(®s->lcr, UART_LCR_BKSE | UART_LCR_8N1);
write32(®s->dll, baud_divisor & 0xff);
write32(®s->dlm, (baud_divisor >> 8) & 0xff);
write32(®s->lcr, UART_LCR_8N1);
}
static void ns16550_tx_byte(unsigned char data)
{
while ((read32(®s->lsr) & UART_LSR_THRE) == 0)
;
write32(®s->thr, data);
}
static void ns16550_tx_flush(void)
{
while (!(read32(®s->lsr) & UART_LSR_TEMT))
;
}
static int ns16550_tst_byte(void)
{
return (read32(®s->lsr) & UART_LSR_DR) != 0;
}
static unsigned char ns16550_rx_byte(void)
{
unsigned long int i = SINGLE_CHAR_TIMEOUT;
while (i-- && !ns16550_tst_byte())
udelay(1);
if (i)
return read32(®s->rbr);
else
return 0x0;
}
void uart_init(int idx)
{
ns16550_init();
}
void uart_tx_byte(int idx, unsigned char data)
{
ns16550_tx_byte(data);
}
void uart_tx_flush(int idx)
{
ns16550_tx_flush();
}
unsigned char uart_rx_byte(int idx)
{
return ns16550_rx_byte();
}
#ifndef __PRE_RAM__
void uart_fill_lb(void *data)
{
struct lb_serial serial;
serial.type = LB_SERIAL_TYPE_MEMORY_MAPPED;
serial.baseaddr = (uintptr_t)regs;
serial.baud = default_baudrate();
serial.regwidth = 4;
lb_add_serial(&serial, data);
lb_add_console(LB_TAG_CONSOLE_SERIAL8250MEM, data);
}
#endif
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