Add beginning basic serial driver

src/kernel/console.cpp

@@ -1,5 +1,5 @@
 #include "console.h"
-#include "io.h"
+#include "serial.h"
 
 const char digits[] = "0123456789abcdef";
 console g_console;
@@ -212,25 +212,28 @@ console_get_screen_out(const font &f, const screen &s, void *scratch, size_t len
 }
 
 
-static bool
-serial_ready()
-{
-	return (inb(COM1 + 5) & 0x20) != 0;
-}
-
-static void
-serial_write(char c) {
-	while (!serial_ready());
-	outb(COM1, c);
-}
-
 
 console::console() :
-	m_screen(nullptr)
+	m_screen(nullptr),
+	m_serial(nullptr)
 {
+}
+
+console::console(serial_port *serial) :
+	m_screen(nullptr),
+	m_serial(serial)
+{
+	if (m_serial) {
 		const char *fgseq = "\x1b[2J";
 		while (*fgseq)
-		serial_write(*fgseq++);
+			m_serial->write(*fgseq++);
+	}
+}
+
+void
+console::echo()
+{
+	putc(m_serial->read());
 }
 
 void
@@ -239,32 +242,40 @@ console::set_color(uint8_t fg, uint8_t bg)
 	if (m_screen)
 		m_screen->set_color(fg, bg);
 
+	if (m_serial) {
 		const char *fgseq = "\x1b[38;5;";
 		while (*fgseq)
-		serial_write(*fgseq++);
-	if (fg >= 100) serial_write('0' + (fg/100));
-	if (fg >=  10) serial_write('0' + (fg/10) % 10);
-	serial_write('0' + fg % 10);
-	serial_write('m');
+			m_serial->write(*fgseq++);
+		if (fg >= 100) m_serial->write('0' + (fg/100));
+		if (fg >=  10) m_serial->write('0' + (fg/10) % 10);
+		m_serial->write('0' + fg % 10);
+		m_serial->write('m');
 
 		const char *bgseq = "\x1b[48;5;";
 		while (*bgseq)
-		serial_write(*bgseq++);
-	if (bg >= 100) serial_write('0' + (bg/100));
-	if (bg >=  10) serial_write('0' + (bg/10) % 10);
-	serial_write('0' + bg % 10);
-	serial_write('m');
+			m_serial->write(*bgseq++);
+		if (bg >= 100) m_serial->write('0' + (bg/100));
+		if (bg >=  10) m_serial->write('0' + (bg/10) % 10);
+		m_serial->write('0' + bg % 10);
+		m_serial->write('m');
+	}
 }
 
 void
 console::puts(const char *message)
 {
-	while (message && *message) {
-		char c = *message++;
+	while (message && *message)
+		putc(*message++);
+}
+
+void
+console::putc(char c)
+{
 	if (m_screen) m_screen->putc(c);
 
-		serial_write(c);
-		if (c == '\n') serial_write('\r');
+	if (m_serial) {
+		m_serial->write(c);
+		if (c == '\r') m_serial->write('\n');
 	}
 }
 

src/kernel/console.h

@@ -6,14 +6,17 @@
 #include "screen.h"
 
 class console_out_screen;
+class serial_port;
 
 class console
 {
 public:
 	console();
+	console(serial_port *serial);
 
 	void set_color(uint8_t fg = 7, uint8_t bg = 0);
 
+	void putc(char c);
 	void puts(const char *message);
 	void vprintf(const char *fmt, va_list args);
 
@@ -33,10 +36,13 @@ public:
 
 	void set_screen(console_out_screen *out) { m_screen = out; }
 
+	void echo();
+
 	static console * get();
 
 private:
 	console_out_screen *m_screen;
+	serial_port *m_serial;
 };
 
 extern console g_console;

src/kernel/interrupts.cpp

@@ -130,7 +130,7 @@ set_idt_entry(uint8_t i, uint64_t addr, uint16_t selector, uint8_t flags)
 	g_idt_table[i].reserved = 0;
 }
 
-void
+static void
 disable_legacy_pic()
 {
 
@@ -154,6 +154,13 @@ disable_legacy_pic()
 	outb(PIC2+1, 0x02); io_wait();
 }
 
+static void
+enable_serial_interrupts()
+{
+	uint8_t ier = inb(COM1+1);
+	outb(COM1+1, ier | 0x1);
+}
+
 void
 interrupts_init()
 {
@@ -186,6 +193,7 @@ interrupts_init()
 
 	idt_write();
 	disable_legacy_pic();
+	enable_serial_interrupts();
 
 	log::info(logs::interrupt, "Interrupts enabled.");
 }
@@ -288,6 +296,11 @@ irq_handler(registers regs)
 		cons->set_color();
 		break;
 
+	case 4:
+		// TODO: move this to a real serial driver
+		cons->echo();
+		break;
+
 	default:
 		cons->set_color(11);
 		cons->printf("\nReceived IRQ interrupt: %d (vec %d)\n",

src/kernel/main.cpp

@@ -7,11 +7,13 @@
 #include "device_manager.h"
 #include "font.h"
 #include "interrupts.h"
+#include "io.h"
 #include "kernel_data.h"
 #include "log.h"
 #include "memory.h"
 #include "memory_pages.h"
 #include "screen.h"
+#include "serial.h"
 
 extern "C" {
 	void do_the_set_registers(popcorn_data *header);
@@ -41,7 +43,9 @@ load_console(const popcorn_data *header)
 void
 kernel_main(popcorn_data *header)
 {
-	console *cons = new (&g_console) console();
+	serial_port *com1 = new (&g_com1) serial_port(COM1);
+	console *cons = new (&g_console) console(com1);
+
 	cons->set_color(0x21, 0x00);
 	cons->puts("Popcorn OS ");
 	cons->set_color(0x08, 0x00);

src/kernel/serial.cpp

@@ -0,0 +1,31 @@
+#include "io.h"
+#include "serial.h"
+
+serial_port g_com1;
+
+
+serial_port::serial_port() :
+	m_port(0)
+{
+}
+
+serial_port::serial_port(uint16_t port) :
+	m_port(port)
+{
+}
+
+bool serial_port::read_ready() { return (inb(m_port + 5) & 0x01) != 0; }
+bool serial_port::write_ready() { return (inb(m_port + 5) & 0x20) != 0; }
+
+char
+serial_port::read() {
+	while (!read_ready());
+	return inb(m_port);
+}
+
+void
+serial_port::write(char c) {
+	while (!write_ready());
+	outb(m_port, c);
+}
+

src/kernel/serial.h

@@ -0,0 +1,25 @@
+#pragma once
+/// \file serial.h
+/// Declarations related to serial ports.
+#include <stdint.h>
+
+class serial_port
+{
+public:
+	/// Constructor.
+	/// \arg port   The IO address of the serial port
+	serial_port(uint16_t port);
+
+	serial_port();
+
+	void write(char c);
+	char read();
+
+private:
+	uint16_t m_port;
+
+	bool read_ready();
+	bool write_ready();
+};
+
+extern serial_port g_com1;