From 93402c2ce5aadfca70133b3e6a43352b0e29cddc Mon Sep 17 00:00:00 2001
From: Michael Gernoth <michael@gernoth.net>
Date: Mon, 23 Aug 2010 13:02:52 +0200
Subject: [PATCH] use CTC unit to generate correct timings for power/reset

---
 bmc/chassis.c | 47 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/bmc/chassis.c b/bmc/chassis.c
index 1b6822e..ed24063 100644
--- a/bmc/chassis.c
+++ b/bmc/chassis.c
@@ -1,4 +1,5 @@
 #include <avr/io.h>
+#include <avr/interrupt.h>
 #include <stdio.h>
 
 #include "chassis.h"
@@ -20,12 +21,22 @@
 #define _CDDR(port) __CDDR(port)
 #define CDDR _CDDR(CHASSISPORT)
 
+static volatile int power_cnt = 0;
+static volatile int reset_cnt = 0;
+
 static void chassis_set_pins(uint8_t pins, uint8_t state);
 
 void chassis_init()
 {
 	chassis_set_pins((1<<POWER_PIN) | (1<<RESET_PIN), 0);
 	CDDR |= ((1<<POWER_PIN) | (1<<RESET_PIN));
+
+	/* About 1ms */
+	OCR0 = ((F_CPU/256)/1000)-1;
+
+	TCCR0 = ((1<<WGM01) | (1<<CS02)); /* CTC, Prescaler 256 */
+	TIMSK |= (1<<OCIE0);
+
 }
 
 static void chassis_set_pins(uint8_t pins, uint8_t state)
@@ -43,26 +54,26 @@ static void chassis_set_pins(uint8_t pins, uint8_t state)
 
 static void chassis_power(int msec)
 {
-	volatile int i;
+	uint8_t old_SREG = SREG;
 
 	chassis_set_pins((1<<POWER_PIN), 1);
 
-	/* FIXME */
-	for(i = 0; i < (msec<<2); i++);
-
-	chassis_set_pins((1<<POWER_PIN), 0);
+	cli();
+	if (!power_cnt)
+		power_cnt = msec;
+	SREG = old_SREG;
 }
 
 static void chassis_reset(int msec)
 {
-	volatile int i;
+	uint8_t old_SREG = SREG;
 
 	chassis_set_pins((1<<RESET_PIN), 1);
 
-	/* FIXME */
-	for(i = 0; i < (msec<<2); i++);
-
-	chassis_set_pins((1<<RESET_PIN), 0);
+	cli();
+	if (!reset_cnt)
+		reset_cnt = msec;
+	SREG = old_SREG;
 }
 
 void chassis_control(unsigned char action)
@@ -91,3 +102,19 @@ void chassis_control(unsigned char action)
 			break;
 	}
 }
+
+ISR(TIMER0_COMP_vect)
+{
+	if (power_cnt) {
+		power_cnt--;
+
+		if (!power_cnt)
+			chassis_set_pins((1<<POWER_PIN), 0);
+	}
+	if (reset_cnt) {
+		reset_cnt--;
+
+		if (!reset_cnt)
+			chassis_set_pins((1<<RESET_PIN), 0);
+	}
+}
-- 
2.39.2