Serial ports (still not working)

scripts/run.mk

@@ -4,5 +4,5 @@ run: quark run-qemu
 .PHONY: run-qemu
 run-qemu:
 	@echo -e $(ARROW) "Running on qemu..."
-	@qemu-system-i386 $(BUILD_DIR)/quark.iso
+	@qemu-system-i386 $(BUILD_DIR)/quark.iso -serial stdio
 	@echo -e $(ARROW) "Finished run"

src/kernel/drivers/serial.c

@@ -0,0 +1,42 @@
+#include "serial.h"
+#include "../arch/i686/io.h"
+
+int serial_initialize(uint8_t port){
+    i686_outb(port + 1, 0x00); // Disable all interrupts
+    i686_outb(port + 3, 0x80); // Enable DLAB
+    i686_outb(port + 0, 0x03); // Divisor high byte (38400 baud)
+    i686_outb(port + 1, 0x00); // Divisor low byte
+    i686_outb(port + 3, 0x03); // 8 bits, no parity, one stop bit
+    i686_outb(port + 2, 0xC7); // Enable FIFO
+    i686_outb(port + 4, 0x0B); // IRQs enabled, RTS/DSR set
+    
+    i686_outb(port + 4, 0x1E); // Loopback mode, test serial chip
+    i686_outb(port + 0, 0xAE); // Test serial chip sending 0xAE
+    
+    if(i686_inb(port + 0) != 0xAE){ // Not working
+        return 1;
+    }
+
+    i686_outb(port + 4, 0x0F); // Normal operation mode
+    return 0;
+}
+
+static int serial_received(uint8_t port){
+    return i686_inb(port + 5) & 0x01;
+}
+
+char serial_read(uint8_t port){
+    while(!serial_received(port));
+
+    return i686_inb(port);
+}
+
+static int serial_tx_empty(uint8_t port){
+    return i686_inb(port + 5) & 0x20;
+}
+
+void serial_write(uint8_t port, char c){
+    while(!serial_tx_empty(port));
+
+    return i686_outb(port, c);
+}

src/kernel/drivers/serial.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <stdint.h>
+
+#define COM1 (uint8_t)0x3F8
+#define COM2 (uint8_t)0x2F8
+#define COM3 (uint8_t)0x3E8
+#define COM4 (uint8_t)0x2E8
+#define COM5 (uint8_t)0x5F8
+#define COM6 (uint8_t)0x4F8
+#define COM7 (uint8_t)0x5E8
+#define COM8 (uint8_t)0x4E8
+
+int serial_initialize(uint8_t port);
+char serial_read(uint8_t port);
+void serial_write(uint8_t port, char c);

src/kernel/main.c

@@ -3,6 +3,7 @@
 #include "hal/hal.h"
 #include "drivers/timer.h"
 #include "drivers/keyboard.h"
+#include "drivers/serial.h"
 
 void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
     hal_initialize();
@@ -10,5 +11,6 @@ void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
     keyboard_initialize();
     
     clear_screen();
+    printf("Serial status: %i\n", serial_initialize(COM1));
     for(;;);
 }

src/kernel/shell.c

@@ -2,6 +2,7 @@
 #include "lib/stdio.h"
 #include "lib/string.h"
 #include "lib/memory.h"
+#include "drivers/serial.h"
 
 int shell_run(char *cmd){
     int ret = 0;
@@ -22,6 +23,13 @@ int shell_run(char *cmd){
     else if(!strcmp(cmd, "clear")){
         clear_screen();
     }
+    else if(!strcmp(cmd, "serial")){
+        serial_write(COM1, 'H');
+        serial_write(COM1, 'E');
+        serial_write(COM1, 'L');
+        serial_write(COM1, 'L');
+        serial_write(COM1, 'O');
+    }
     else{
         printf("SHELL: Unknown command \"%s\"\n", cmd);
         ret = 127;