You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
RIOT/cpu/x86/x86_uart.c

103 lines
2.5 KiB
C

/*
* Copyright (C) 2014 René Kijewski <rene.kijewski@fu-berlin.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @ingroup x86-irq
* @{
*
* @file
* @brief UART reading and writing.
*
* @author René Kijewski <rene.kijewski@fu-berlin.de>
*
* @}
*/
#include "board.h"
#include "x86_ports.h"
#include "x86_uart.h"
#include <cpu.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
void x86_early_init_uart(void)
{
outb(UART_PORT + IER, 0x00); /* Disable all interrupts */
outb(UART_PORT + LCR, LCR_DLAB);
outb(UART_PORT + DLL, BAUD_LL); /* Set divisor (lo byte) */
outb(UART_PORT + DLH, BAUD_HL); /* (hi byte) */
outb(UART_PORT + LCR, LCR_WORD_BITS_8 | LCR_PAR_NONE | LCR_STOP_BITS_1);
outb(UART_PORT + FCR, FCR_ENABLE | FCR_CLR_RECV | FCR_CLR_SEND | FCR_TRIGGER_16);
outb(UART_PORT + MCR, MCR_DSR | MCR_RTS | MCR_AUX2);
}
static bool is_output_empty(void)
{
uint8_t data = inb(UART_PORT + LSR);
return (data & 0x20) != 0;
}
static bool is_input_empty(void)
{
uint8_t data = inb(UART_PORT + LSR);
return (data & 0x01) == 0;
}
ssize_t x86_uart_write(const char *buf, size_t len)
{
if (!UART_PORT) {
return -1;
}
(void) buf;
size_t written = 0;
while (written < len) {
while (!is_output_empty()) {
__asm__ volatile ("pause");
}
outb(UART_PORT + THR, buf[written]);
++written;
}
return written;
}
ssize_t x86_uart_read(char *buf, size_t len)
{
if (!UART_PORT) {
return -1;
}
size_t read = 0;
while (read < len) {
while (!is_input_empty()) {
__asm__ volatile ("pause");
}
buf[read] = inb(UART_PORT + RBR);
++read;
}
return read;
}
void x86_init_uart(void)
{
}