From f3e85eedc434da973267f360abdbb79cb6f24100 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 1 Jul 2021 21:13:01 +0200
Subject: Timing is everything

---
 kernel/drivers/pit.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 kernel/drivers/pit.c

(limited to 'kernel/drivers/pit.c')

diff --git a/kernel/drivers/pit.c b/kernel/drivers/pit.c
new file mode 100644
index 0000000..abba5e8
--- /dev/null
+++ b/kernel/drivers/pit.c
@@ -0,0 +1,20 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <def.h>
+#include <drivers/cpu.h>
+#include <drivers/pit.h>
+#include <timer.h>
+
+CLEAR static void pit_phase(u32 hz)
+{
+	u32 divisor = 3579545 / 3 / hz;
+	outb(0x43, 0x36); // 01 10 11 0b // CTR, RW, MODE, BCD
+	outb(0x40, (u8)(divisor & 0xFF));
+	outb(0x40, (u8)(divisor >> 8));
+}
+
+CLEAR void pit_install(void)
+{
+	pit_phase(1000);
+	timer_install_handler();
+}
-- 
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