From 34aad175e9c90dcd9f49dc72b0d0f230d508a994 Mon Sep 17 00:00:00 2001
From: Ali Mashtizadeh <mashti@cs.stanford.edu>
Date: Sun, 13 Jul 2014 13:04:14 -0700
Subject: [PATCH] Serial support

---
 sys/SConscript        |  1 +
 sys/dev/console.c     | 22 ++++++++++
 sys/dev/x86/sercons.c | 96 +++++++++++++++++++++++++++++++++++++++++++
 sys/dev/x86/sercons.h |  8 ++++
 4 files changed, 127 insertions(+)

diff --git a/sys/SConscript b/sys/SConscript
index e6d0edd..b2eca15 100644
--- a/sys/SConscript
+++ b/sys/SConscript
@@ -20,6 +20,7 @@ src_amd64 = [
     "amd64/ioapic.c",
     "amd64/irq.c",
     "dev/x86/debugcons.c",
+    "dev/x86/sercons.c",
     "dev/x86/vgacons.c",
     "dev/x86/ide.c",
 ]
diff --git a/sys/dev/console.c b/sys/dev/console.c
index c0eee2a..f66b34d 100644
--- a/sys/dev/console.c
+++ b/sys/dev/console.c
@@ -3,21 +3,42 @@
 
 #include "console.h"
 #include "x86/vgacons.h"
+#include "x86/sercons.h"
 #include "x86/debugcons.h"
 
+/*
+ * Initialize console devices for debugging purposes.  At this point interrupts 
+ * and device state is not initialized.
+ */
 void
 Console_Init()
 {
     VGA_Init();
+    Serial_Init();
     DebugConsole_Init();
 
     Console_Puts("Castor Operating System\n");
 }
 
+/*
+ * Setup interrupts and input devices that may not be ready
+ */
+void
+Console_LateInit()
+{
+    Serial_LateInit();
+}
+
+void
+Console_Getc(char ch)
+{
+}
+
 void
 Console_Putc(char ch)
 {
     VGA_Putc(ch);
+    Serial_Putc(ch);
     DebugConsole_Putc(ch);
 }
 
@@ -25,6 +46,7 @@ void
 Console_Puts(const char *str)
 {
     VGA_Puts(str);
+    Serial_Puts(str);
     DebugConsole_Puts(str);
 }
 
diff --git a/sys/dev/x86/sercons.c b/sys/dev/x86/sercons.c
index e69de29..b6bf95d 100644
--- a/sys/dev/x86/sercons.c
+++ b/sys/dev/x86/sercons.c
@@ -0,0 +1,96 @@
+
+#include <stdint.h>
+
+#include <kassert.h>
+#include <irq.h>
+
+#include "ioport.h"
+#include "sercons.h"
+
+#define COM1_BASE		0x3F8
+#define COM2_BASE		0x2F8
+#define COM3_BASE		0x3E8
+#define COM4_BASE		0x2E8
+
+#define COM1_IRQ		4
+#define COM2_IRQ		3
+#define COM3_IRQ		4
+#define COM4_IRQ		3
+
+// Inputs
+#define UART_OFFSET_DATA	0   /* Data Register */
+#define UART_OFFSET_IER		1   /* Interrupt Enable Register */
+#define UART_OFFSET_IIR		2   /* Interrupt Identification & FIFO Control */
+#define UART_OFFSET_LCR		3   /* Line Control Register */
+#define UART_LCR_DLAB		0x80
+#define UART_LCR_8N1		0x03
+#define UART_OFFSET_MCR		4   /* Modem Control Register */
+#define UART_OFFSET_LSR		5   /* Line Status Register */
+#define UART_OFFSET_MSR		6   /* Modem Status Register */
+#define UART_OFFSET_SR		7   /* Scratch Register */
+
+#define UART_OFFSET_DIVLO	0   /* Divisors DLAB == 1 */
+#define UART_OFFSET_DIVHI	1
+
+IRQHandler handler;
+uint16_t base;
+uint8_t irq;
+
+void Serial_Init(void)
+{
+    base = COM1_BASE;
+    irq = COM1_IRQ;
+
+    // Disable interrupts
+    outb(base + UART_OFFSET_IER, 0);
+
+    // Enable DLAB
+    outb(base + UART_OFFSET_LCR, UART_LCR_DLAB);
+    outb(base + UART_OFFSET_DIVLO, 1); // 115200 Baud
+    outb(base + UART_OFFSET_DIVLO, 0);
+    outb(base + UART_OFFSET_LCR, UART_LCR_8N1);
+
+    // Enable interrupts
+    outb(base + UART_OFFSET_IIR, 0xC7);
+    outb(base + UART_OFFSET_MCR, 0x0B);
+}
+
+void Serial_LateInit(void)
+{
+    handler.irq = irq;
+    handler.cb = &Serial_Interrupt;
+    handler.arg = NULL;
+
+    IRQ_Register(irq, &handler);
+}
+
+void Serial_Interrupt(void *arg)
+{
+    kprintf("Serial interrupt!\n");
+}
+
+char Serial_Getc()
+{
+    while ((inb(base + UART_OFFSET_LSR) & 0x01) == 0)
+    {
+	// Timeout!
+    }
+    return inb(base + UART_OFFSET_DATA);
+}
+
+void Serial_Putc(char ch)
+{
+    while ((inb(base + UART_OFFSET_LSR) & 0x20) == 0)
+    {
+	// Timeout!
+    }
+    outb(base + UART_OFFSET_DATA, ch);
+}
+
+void Serial_Puts(const char *str)
+{
+    const char *p = str;
+    while (*p != '\0')
+	Serial_Putc(*p++);
+}
+
diff --git a/sys/dev/x86/sercons.h b/sys/dev/x86/sercons.h
index e69de29..d676d41 100644
--- a/sys/dev/x86/sercons.h
+++ b/sys/dev/x86/sercons.h
@@ -0,0 +1,8 @@
+
+void Serial_Init(void);
+void Serial_LateInit(void);
+void Serial_Interrupt(void *arg);
+char Serial_Getc();
+void Serial_Putc(char ch);
+void Serial_Puts(const char *str);
+