From 007c5b5c429d9d524b3f88884cbebab73d15a7ea Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 10 Oct 2019 18:56:48 +0200
Subject: Implemented serial console debugging

Still trying to fix the EDID table
---
 src/kernel/io/io.c | 22 ++++++++++++++++++++++
 src/kernel/io/io.h | 11 +++++++++++
 2 files changed, 33 insertions(+)

(limited to 'src/kernel/io')

diff --git a/src/kernel/io/io.c b/src/kernel/io/io.c
index 74776ee..7cb364c 100644
--- a/src/kernel/io/io.c
+++ b/src/kernel/io/io.c
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include "../lib/lib.h"
 
 uint8_t receive_b(uint16_t port) {
     unsigned char value;
@@ -29,3 +30,24 @@ void send_w(uint16_t port, uint16_t data) {
 void send_l(uint16_t port, uint32_t data) {
     asm volatile ("outl %0, %1"::"a" (data), "Nd"(port));
 }
+
+void init_serial() {
+    send_b(0x3f8 + 1, 0x00);
+    send_b(0x3f8 + 3, 0x80);
+    send_b(0x3f8 + 0, 0x03);
+    send_b(0x3f8 + 1, 0x00);
+    send_b(0x3f8 + 3, 0x03);
+    send_b(0x3f8 + 2, 0xC7);
+    send_b(0x3f8 + 4, 0x0B);
+}
+
+int is_transmit_empty() {
+    return receive_b(0x3f8 + 5) & 0x20;
+}
+
+void write_serial(char *data) {
+    for (size_t i = 0; i < strlen(data); i++) {
+        while (is_transmit_empty() == 0);
+        send_b(0x3f8, data[i]);
+    }
+}
diff --git a/src/kernel/io/io.h b/src/kernel/io/io.h
index 8e39f84..e72d794 100644
--- a/src/kernel/io/io.h
+++ b/src/kernel/io/io.h
@@ -45,4 +45,15 @@ void send_w(uint16_t port, uint16_t data);
  */
 void send_l(uint16_t port, uint32_t data);
 
+/**
+ * Initialize the serial conenction
+ */
+void init_serial();
+
+/**
+ * Write a string to the serial port (QEMU logging)
+ * @param data
+ */
+void write_serial(char *data);
+
 #endif
-- 
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