1 files changed, 93 insertions, 0 deletions
diff --git a/src/pc80/serial.c b/src/pc80/serial.c
new file mode 100644
index 0000000000..b10d22dcba
--- /dev/null
+++ b/src/pc80/serial.c
@@ -0,0 +1,93 @@
+#include <part/fallback_boot.h>
+
+/* Base Address */
+#ifndef TTYS0_BASE
+#define TTYS0_BASE 0x3f8
+#endif
+
+#ifndef TTYS0_BAUD
+#define TTYS0_BAUD 115200
+#endif
+
+#if ((115200%TTYS0_BAUD) != 0)
+#error Bad ttys0 baud rate
+#endif
+
+#define TTYS0_DIV	(115200/TTYS0_BAUD)
+
+/* Line Control Settings */
+#ifndef TTYS0_LCS
+/* Set 8bit, 1 stop bit, no parity */
+#define TTYS0_LCS	0x3
+#endif
+
+#define UART_LCS	TTYS0_LCS
+
+/* Data */
+#define UART_RBR 0x00
+#define UART_TBR 0x00
+
+/* Control */
+#define UART_IER 0x01
+#define UART_IIR 0x02
+#define UART_FCR 0x02
+#define UART_LCR 0x03
+#define UART_MCR 0x04
+#define UART_DLL 0x00
+#define UART_DLM 0x01
+
+/* Status */
+#define UART_LSR 0x05
+#define UART_MSR 0x06
+#define UART_SCR 0x07
+
+static int uart_can_tx_byte(void)
+{
+	return inb(TTYS0_BASE + UART_LSR) & 0x20;
+}
+
+static void uart_wait_to_tx_byte(void)
+{
+	while(!uart_can_tx_byte())
+		;
+}
+
+static void uart_wait_until_sent(void)
+{
+	while(!(inb(TTYS0_BASE + UART_LSR) & 0x40)) 
+		;
+}
+
+static void uart_tx_byte(unsigned char data)
+{
+	uart_wait_to_tx_byte();
+	outb(data, TTYS0_BASE + UART_TBR);
+	/* Make certain the data clears the fifos */
+	uart_wait_until_sent();
+}
+
+static void uart_init(void)
+{
+	/* disable interrupts */
+	outb(0x0, TTYS0_BASE + UART_IER);
+	/* enable fifo's */
+	outb(0x01, TTYS0_BASE + UART_FCR);
+	/* Set Baud Rate Divisor to 12 ==> 115200 Baud */
+	outb(0x80 | UART_LCS, TTYS0_BASE + UART_LCR);
+#if 0 &&  USE_OPTION_TABLE == 1
+ {
+		static const unsigned char divisor[] = { 1,2,3,6,12,24,48,96 };
+		unsigned ttys0_div, ttys0_index;
+		outb(RTC_BOOT_BYTE + 1, 0x70);
+		ttys0_index = inb(0x71);
+		ttys0_index &= 7;
+		ttys0_div = divisor[ttys0_index];
+		outb(ttys0_div & 0xff, TTYS0_BASE + UART_DLL);
+		outb(0, TTYS0_BASE + UART_DLM);
+ }
+#else
+		outb(TTYS0_DIV & 0xFF,   TTYS0_BASE + UART_DLL);
+		outb((TTYS0_DIV >> 8) & 0xFF,    TTYS0_BASE + UART_DLM);
+#endif
+	outb(UART_LCS, TTYS0_BASE + UART_LCR);
+}