i386: add serial port support

Add support for serial communication in the i386 architecture.

Signed-off-by: Danny Holman <dholman@gymli.xyz>

1 files changed, 40 insertions, 0 deletions

diff --git a/arch/i386/serial.c b/arch/i386/serial.c
new file mode 100644
index 0000000..b172e82
--- /dev/null
+++ b/arch/i386/serial.c
@@ -0,0 +1,40 @@
+#include <kernel/serial.h>
+#include "pic.h"
+
+#define PORT 0x3f8
+
+static int serial_init(void) {
+        outb(PORT + 1, 0x00);
+        outb(PORT + 3, 0x80);
+        outb(PORT + 0, 0x03);
+        outb(PORT + 1, 0x00);
+        outb(PORT + 3, 0x03);
+        outb(PORT + 2, 0xC7);
+        outb(PORT + 4, 0x0B);
+        outb(PORT + 4, 0x1E);
+        outb(PORT + 0, 0xAE);
+
+        if (inb(PORT + 0) != 0xAE)
+                return -1;
+
+        outb(PORT + 4, 0x0F);
+        return 0;
+}
+
+int serial_recieved(void) {
+        return inb(PORT + 5) & 1;
+}
+
+char read_serial(void) {
+        while (serial_recieved() == 0);
+        return inb(PORT);
+}
+
+int is_transmit_empty(void) {
+        return inb(PORT + 5) & 0x20;
+}
+
+void write_serial(char a) {
+        while (is_transmit_empty() == 0);
+        outb(PORT, a);
+}