add serial port

Makefile

@@ -145,6 +145,7 @@ run: $(IMAGE)
 	@qemu-system-i386		\
 	-boot order=a			\
 	-drive file=$<,format=raw	\
+	-serial stdio
 
 gdb: $(IMAGE)
 	@qemu-system-i386		\

include/tty.h

@@ -56,4 +56,8 @@ void init_screen(TTY* tty);
 void out_char(CONSOLE* con, char ch);
 int is_current_console(CONSOLE* con);
 
+int init_serial();
+char read_serial();
+void write_serial(char a);
+
 #endif /* _ORANGES_TTY_H_ */

kernel/Makefrag

@@ -30,6 +30,7 @@ KERN_SRCFILES :=kernel/kernel.asm	\
 		kernel/i8259.c	\
 		kernel/testfunc.c	\
 		kernel/protect.c	\
+		kernel/serialport.c \
 		lib/klib.c		\
 		lib/kliba.asm		\
 

kernel/main.c

@@ -21,6 +21,7 @@
 #include "x86.h"
 #include "assert.h"
 #include "stdio.h"
+#include "tty.h"
 
 static int initialize_processes();	//added by xw, 18/5/26
 static int initialize_cpus();		//added by xw, 18/6/2
@@ -30,12 +31,13 @@ static int initialize_cpus();		//added by xw, 18/6/2
  *======================================================================*/
 int kernel_main()
 {
+	init_serial();
 	int error;
 
 	disp_pos = 0;
 	for (int i = 0; i < 25; i++) {
 		for (int j = 0; j < 80; j++) {
-			kprintf(" ");
+			disp_str(" ");
 		}
 	}
 	disp_pos = 0;

kernel/serialport.c

@@ -0,0 +1,45 @@
+#include "x86.h"
+#include "tty.h"
+
+#define PORT 0x3f8          // COM1
+ 
+int init_serial() {
+   outb(PORT + 1, 0x00);    // Disable all interrupts
+   outb(PORT + 3, 0x80);    // Enable DLAB (set baud rate divisor)
+   outb(PORT + 0, 0x03);    // Set divisor to 3 (lo byte) 38400 baud
+   outb(PORT + 1, 0x00);    //                  (hi byte)
+   outb(PORT + 3, 0x03);    // 8 bits, no parity, one stop bit
+   outb(PORT + 2, 0xC7);    // Enable FIFO, clear them, with 14-byte threshold
+   outb(PORT + 4, 0x0B);    // IRQs enabled, RTS/DSR set
+   outb(PORT + 4, 0x1E);    // Set in loopback mode, test the serial chip
+   outb(PORT + 0, 0xAE);    // Test serial chip (send byte 0xAE and check if serial returns same byte)
+ 
+   // Check if serial is faulty (i.e: not same byte as sent)
+   if(inb(PORT + 0) != 0xAE) {
+      return 1;
+   }
+ 
+   // If serial is not faulty set it in normal operation mode
+   // (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
+   outb(PORT + 4, 0x0F);
+   return 0;
+}
+static inline int is_transmit_empty() {
+   return inb(PORT + 5) & 0x20;
+}
+
+static inline int serial_received() {
+   return inb(PORT + 5) & 1;
+}
+ 
+char read_serial() {
+   while (serial_received() == 0);
+ 
+   return inb(PORT);
+}
+
+void write_serial(char a) {
+   while (is_transmit_empty() == 0);
+ 
+   outb(PORT,a);
+}

lib/kprintf.c

@@ -3,6 +3,11 @@
 #include "proc.h"
 #include "global.h"
 #include "proto.h"
+#include "tty.h"
+
+static void serialputch(int ch, void * cnt) {
+	write_serial(ch);
+}
 
 static void 
 kprintfputch(int ch, void *b)
@@ -15,7 +20,8 @@ int
 vkprintf(const char *fmt, va_list ap)
 {
 
-	vprintfmt((void*)kprintfputch, NULL, fmt, ap);
+	// vprintfmt((void*)kprintfputch, NULL, fmt, ap);
+	vprintfmt((void*)serialputch, NULL, fmt, ap);
 
 	return 0;
 }