From e931b1fe079024613c42c0c3fac66ac1421829f6 Mon Sep 17 00:00:00 2001
From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Fri, 7 Nov 2008 14:51:42 -0500
Subject: [PATCH] Add a small serial driver

---
 aseg/Makefile |  3 ++-
 lib/serial.c  | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 lib/serial.c

diff --git a/aseg/Makefile b/aseg/Makefile
index 0ffd379..76eaa45 100644
--- a/aseg/Makefile
+++ b/aseg/Makefile
@@ -30,7 +30,8 @@ LWIP_OBJS = \
 OBJS=counter.o firstrun.o ../pci/pci-raw.o ../lib/minilib.o ../lib/console.o \
 	../ich2/smram-ich2.o ../ich2/smi.o vga-overlay.o packet.o \
 	../lib/sprintf.o ../lib/doprnt.o ../pci/pci.o ../net/net.o \
-	../ich2/ich2-timer.o ../pci/pci-bother.o ../net/3c90x.o keyboard.o $(LWIP_OBJS)
+	../ich2/ich2-timer.o ../pci/pci-bother.o ../net/3c90x.o keyboard.o \
+	../lib/serial.o $(LWIP_OBJS)
 
 all: aseg.elf
 
diff --git a/lib/serial.c b/lib/serial.c
new file mode 100644
index 0000000..5318c95
--- /dev/null
+++ b/lib/serial.c
@@ -0,0 +1,50 @@
+#include <minilib.h>
+#include <io.h>
+
+#define SER_BASE 0x3F8
+#define SER_THR 0x0
+#define SER_RBR 0x0
+#define SER_DLL 0x0
+#define SER_IER 0x1
+#define SER_DLM 0x1
+#define SER_IIR 0x2
+#define SER_FCR 0x2
+#define SER_LCR 0x3
+#define SER_LCR_DLAB 0x80
+#define SER_MCR 0x4
+#define SER_LSR 0x5
+#define SER_LSR_THR_EMPTY 0x20
+#define SER_MSR 0x6
+#define SER_SR 0x7
+
+#define SER_BAUD_BASE 115200
+#define SER_BAUD_REQ 115200
+
+void _outb(unsigned short port, unsigned char d)
+{
+	outb(SER_BASE + port, d);
+}
+
+unsigned char _inb(unsigned short port)
+{
+	return inb(SER_BASE + port);
+}
+
+void serial_init()
+{
+	unsigned short baud = SER_BAUD_REQ / SER_BAUD_BASE;
+	_outb(SER_LCR, inb(SER_LCR) | SER_LCR_DLAB);
+	_outb(SER_DLL, baud & 0xFF);
+	_outb(SER_DLM, baud >> 8);
+	_outb(SER_LCR, inb(SER_LCR) & ~SER_LCR_DLAB);
+	_outb(SER_IER, 0x0);
+	_outb(SER_FCR, 0x0);	/* FIFOs off */
+	_outb(SER_LCR, 0x03);	/* 8 data bits, one stop bit, no parity */
+}
+
+void serial_tx(unsigned char c)
+{
+	while (!(_inb(SER_LSR) & SER_LSR_THR_EMPTY))
+		;
+	_outb(SER_THR, c);
+}
-- 
2.39.2