/* * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include <arch/io.h> #include <console/uart.h> #include <trace.h> #include "uart8250reg.h" #ifndef __ROMCC__ #include <boot/coreboot_tables.h> #endif /* Should support 8250, 16450, 16550, 16550A type UARTs */ /* Nominal values only, good for the range of choices Kconfig offers for * set of standard baudrates. */ #define BAUDRATE_REFCLK (115200) #define BAUDRATE_OVERSAMPLE (1) /* 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. * * Estimated that inb() from UART takes 1 microsecond. */ #define SINGLE_CHAR_TIMEOUT (50 * 1000) #define FIFO_TIMEOUT (16 * SINGLE_CHAR_TIMEOUT) static int uart8250_can_tx_byte(unsigned base_port) { return inb(base_port + UART_LSR) & UART_LSR_THRE; } static void uart8250_tx_byte(unsigned base_port, unsigned char data) { unsigned long int i = SINGLE_CHAR_TIMEOUT; while (i-- && !uart8250_can_tx_byte(base_port)); outb(data, base_port + UART_TBR); } static void uart8250_tx_flush(unsigned base_port) { unsigned long int i = FIFO_TIMEOUT; while (i-- && !(inb(base_port + UART_LSR) & UART_LSR_TEMT)); } static int uart8250_can_rx_byte(unsigned base_port) { return inb(base_port + UART_LSR) & UART_LSR_DR; } static unsigned char uart8250_rx_byte(unsigned base_port) { unsigned long int i = SINGLE_CHAR_TIMEOUT; while (i-- && !uart8250_can_rx_byte(base_port)); if (i) return inb(base_port + UART_RBR); else return 0x0; } static void uart8250_init(unsigned base_port, unsigned divisor) { DISABLE_TRACE; /* Disable interrupts */ outb(0x0, base_port + UART_IER); /* Enable FIFOs */ outb(UART_FCR_FIFO_EN, base_port + UART_FCR); /* assert DTR and RTS so the other end is happy */ outb(UART_MCR_DTR | UART_MCR_RTS, base_port + UART_MCR); /* DLAB on */ outb(UART_LCR_DLAB | CONFIG_TTYS0_LCS, base_port + UART_LCR); /* Set Baud Rate Divisor. 12 ==> 9600 Baud */ outb(divisor & 0xFF, base_port + UART_DLL); outb((divisor >> 8) & 0xFF, base_port + UART_DLM); /* Set to 3 for 8N1 */ outb(CONFIG_TTYS0_LCS, base_port + UART_LCR); ENABLE_TRACE; } /* FIXME: Needs uart index from Kconfig. * Already use array as a work-around for ROMCC. */ static const unsigned bases[1] = { CONFIG_TTYS0_BASE }; unsigned int uart_platform_base(int idx) { return bases[idx]; } void uart_init(void) { unsigned int div; div = uart_baudrate_divisor(default_baudrate(), BAUDRATE_REFCLK, BAUDRATE_OVERSAMPLE); uart8250_init(bases[0], div); } void uart_tx_byte(unsigned char data) { uart8250_tx_byte(bases[0], data); } unsigned char uart_rx_byte(void) { return uart8250_rx_byte(bases[0]); } int uart_can_rx_byte(void) { return uart8250_can_rx_byte(bases[0]); } void uart_tx_flush(void) { uart8250_tx_flush(bases[0]); } #ifndef __PRE_RAM__ void uart_fill_lb(void *data) { struct lb_serial serial; serial.type = LB_SERIAL_TYPE_IO_MAPPED; serial.baseaddr = uart_platform_base(0); serial.baud = default_baudrate(); lb_add_serial(&serial, data); lb_add_console(LB_TAG_CONSOLE_SERIAL8250, data); } #endif