From e93cf7db3c6a941f93a3a76dfd56a8f4d24d5d77 Mon Sep 17 00:00:00 2001
From: Arnau478 <arnauxabia@gmail.com>
Date: Sat, 18 Jun 2022 19:19:03 +0200
Subject: [PATCH] APIC timer driver

---
 src/kernel/arch/i686/isr.c |  8 ++++++++
 src/kernel/arch/i686/pic.c |  4 ++--
 src/kernel/arch/i686/pic.h |  5 +++++
 src/kernel/drivers/timer.c | 11 +++++++++++
 src/kernel/drivers/timer.h |  3 +++
 src/kernel/main.c          |  3 ++-
 6 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 src/kernel/drivers/timer.c
 create mode 100644 src/kernel/drivers/timer.h

diff --git a/src/kernel/arch/i686/isr.c b/src/kernel/arch/i686/isr.c
index d31fd15..b6d822b 100644
--- a/src/kernel/arch/i686/isr.c
+++ b/src/kernel/arch/i686/isr.c
@@ -57,6 +57,14 @@ void i686_isr_initialize(){
 void __attribute__((cdecl)) i686_isr_handler(registers *regs){
     if(g_isr_handlers[regs->interrupt] != NULL){
         g_isr_handlers[regs->interrupt](regs);
+
+        // Send EOI to PIC if necessary
+        if(regs->interrupt >= PIC1_VEC_OFFSET && regs->interrupt < PIC1_VEC_OFFSET+8){
+            i686_outb(PIC1_CMD_PORT, PIC_EOI);
+        }
+        else if(regs->interrupt >= PIC2_VEC_OFFSET && regs->interrupt < PIC2_VEC_OFFSET+8){
+            i686_outb(PIC2_CMD_PORT, PIC_EOI);
+        }
     }
     else if(regs->interrupt >= 32){
         printf("Unhandled interrupt %i\n", regs->interrupt);
diff --git a/src/kernel/arch/i686/pic.c b/src/kernel/arch/i686/pic.c
index 105970e..8e32dbc 100644
--- a/src/kernel/arch/i686/pic.c
+++ b/src/kernel/arch/i686/pic.c
@@ -14,8 +14,8 @@ void i686_pic_initialize(){
     i686_outb(PIC2_CMD_PORT, 0x11); // PIC2
 
     // ICW2: Remap IRQs
-    i686_outb(PIC1_DATA_PORT, 0x20); // PIC1 remapped to 0x20 (32)
-    i686_outb(PIC2_DATA_PORT, 0x28); // PIC2 remapped to 0x28 (40)
+    i686_outb(PIC1_DATA_PORT, PIC1_VEC_OFFSET); // PIC1 remapped to PIC1_VEC_OFFSET
+    i686_outb(PIC2_DATA_PORT, PIC2_VEC_OFFSET); // PIC2 remapped to PIC2_VEC_OFFSET
 
     // ICW3: Cascade settings
     i686_outb(PIC1_DATA_PORT, 0x04); // PIC1 is told that slave PIC is at IRQ2
diff --git a/src/kernel/arch/i686/pic.h b/src/kernel/arch/i686/pic.h
index 12dbada..24aad8b 100644
--- a/src/kernel/arch/i686/pic.h
+++ b/src/kernel/arch/i686/pic.h
@@ -5,4 +5,9 @@
 #define PIC2_CMD_PORT 0xA0
 #define PIC2_DATA_PORT 0xA1
 
+#define PIC1_VEC_OFFSET 0x20
+#define PIC2_VEC_OFFSET 0x28
+
+#define PIC_EOI 0x20
+
 void i686_pic_initialize();
diff --git a/src/kernel/drivers/timer.c b/src/kernel/drivers/timer.c
new file mode 100644
index 0000000..ff4e7dd
--- /dev/null
+++ b/src/kernel/drivers/timer.c
@@ -0,0 +1,11 @@
+#include "timer.h"
+#include "../arch/i686/isr.h"
+#include "../stdio.h"
+
+static void timer_handler(registers *regs){
+    printf("TICK\n");
+}
+
+void timer_initialize(){
+    i686_isr_register_handler(IRQ(0), timer_handler);
+}
diff --git a/src/kernel/drivers/timer.h b/src/kernel/drivers/timer.h
new file mode 100644
index 0000000..4f33b4d
--- /dev/null
+++ b/src/kernel/drivers/timer.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void timer_initialize();
diff --git a/src/kernel/main.c b/src/kernel/main.c
index 4d5dee2..ec2467e 100644
--- a/src/kernel/main.c
+++ b/src/kernel/main.c
@@ -1,13 +1,14 @@
 #include <stdint.h>
 #include "stdio.h"
 #include "hal/hal.h"
+#include "drivers/timer.h"
 
 void __attribute__((cdecl)) kmain(uint64_t magic, uint64_t addr){
     hal_initialize();
+    timer_initialize();
     
     puts("\x1b[33mWARNING\x1b[0m");
     printf(": amazing %s ahead!\n", "math");
     printf("%i+%i=%i\n", 1, 1, 2);
-    printf("0/0=%i", 0/0);
     for(;;);
 }