1 files changed, 131 insertions, 0 deletions
diff --git a/src/drivers/uart/uart8250io.c b/src/drivers/uart/uart8250io.c
new file mode 100644
index 0000000000..e4e8b6cfd7
--- /dev/null
+++ b/src/drivers/uart/uart8250io.c
@@ -0,0 +1,131 @@
+/*
+ * 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"
+
+/* 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 };
+
+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]);
+}