Initial commit

kernel/cpu/timer.c

@@ -0,0 +1,26 @@
+//
+// Created by rick on 9/22/19.
+//
+
+#include "timer.h"
+
+#include <drivers/ports.h>
+#include <cpu/isr.h>
+
+u32 tick = 0;
+
+static void timer_callback(registers_t regs) {
+    tick++;
+}
+
+int init_timer(u32 freq) {
+    register_interrupt_handler(IRQ0, timer_callback);
+
+    u32 divisor = 1193180 / freq;
+    u8 low = (u8) (divisor & 0xFF);
+    u8 high = (u8) ((divisor >> 8) & 0xFF);
+    port_byte_out(PORT_PIT_COMMAND, PIT_MODE_BIN | PIT_MODE_SQUARE_WAVE | PIT_ACCESS_MODE_HL | PIT_CHANNEL_0);
+    port_byte_out(PORT_PIT_DATA_0, low);
+    port_byte_out(PORT_PIT_DATA_0, high);
+    return 0;
+}