2 * This file is part of the coreboot project.
4 * Copyright (C) 2003 Eric Biederman
5 * Copyright (C) 2006-2010 coresystems GmbH
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; version 2 of the License.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
23 #include <pc80/mc146818rtc.h>
26 #if CONFIG_USE_OPTION_TABLE
27 #include "option_table.h"
30 /* Should support 8250, 16450, 16550, 16550A type UARTs */
32 static inline int uart8250_can_tx_byte(unsigned base_port)
34 return inb(base_port + UART_LSR) & UART_MSR_DSR;
37 static inline void uart8250_wait_to_tx_byte(unsigned base_port)
39 while(!uart8250_can_tx_byte(base_port))
43 static inline void uart8250_wait_until_sent(unsigned base_port)
45 while(!(inb(base_port + UART_LSR) & UART_LSR_TEMT))
49 void uart8250_tx_byte(unsigned base_port, unsigned char data)
51 uart8250_wait_to_tx_byte(base_port);
52 outb(data, base_port + UART_TBR);
55 void uart8250_tx_flush(unsigned base_port)
57 uart8250_wait_until_sent(base_port);
60 int uart8250_can_rx_byte(unsigned base_port)
62 return inb(base_port + UART_LSR) & UART_LSR_DR;
65 unsigned char uart8250_rx_byte(unsigned base_port)
67 while(!uart8250_can_rx_byte(base_port))
69 return inb(base_port + UART_RBR);
72 void uart8250_init(unsigned base_port, unsigned divisor)
75 /* Disable interrupts */
76 outb(0x0, base_port + UART_IER);
78 outb(UART_FCR_FIFO_EN, base_port + UART_FCR);
80 /* assert DTR and RTS so the other end is happy */
81 outb(UART_MCR_DTR | UART_MCR_RTS, base_port + UART_MCR);
84 outb(UART_LCR_DLAB | CONFIG_TTYS0_LCS, base_port + UART_LCR);
86 /* Set Baud Rate Divisor. 12 ==> 115200 Baud */
87 outb(divisor & 0xFF, base_port + UART_DLL);
88 outb((divisor >> 8) & 0xFF, base_port + UART_DLM);
90 /* Set to 3 for 8N1 */
91 outb(CONFIG_TTYS0_LCS, base_port + UART_LCR);
97 /* TODO the divisor calculation is hard coded to standard UARTs. Some
98 * UARTs won't work with these values. This should be a property of the
99 * UART used, worst case a Kconfig variable. For now live with hard
100 * codes as the only devices that might be different are the iWave
101 * iRainbowG6 and the OXPCIe952 card (and the latter is memory mapped)
103 unsigned int div = (115200 / CONFIG_TTYS0_BAUD);
105 #if !defined(__SMM__) && CONFIG_USE_OPTION_TABLE
106 static const unsigned char divisor[8] = { 1, 2, 3, 6, 12, 24, 48, 96 };
107 unsigned b_index = 0;
108 #if defined(__PRE_RAM__)
109 b_index = read_option(baud_rate, 0);
111 div = divisor[b_index];
113 if (get_option(&b_index, "baud_rate") == 0) {
114 div = divisor[b_index];
119 uart8250_init(CONFIG_TTYS0_BASE, div);