From 232fb58f27bd7a7988a2c54ee94f561454becf81 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Thu, 22 Jun 2000 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2000-06-22

---
 pc/devarch.c |  4 ++--
 pc/fns.h     |  4 +++-
 pc/i8253.c   | 19 +++++++++++++++----
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/pc/devarch.c b/pc/devarch.c
index b4fd363dfe4f60f0f444150a393fa0be8fa9f651..4b6b3168836e7967a6e8759498bbffce1ff500b3 100644
--- a/pc/devarch.c
+++ b/pc/devarch.c
@@ -587,10 +587,10 @@ cycletimer(uvlong *hz)
 {
 	uvlong tsc;
 
-	rdmsr(0x10, (vlong*)&tsc);
-	m->fastclock = tsc;
 	if(hz != nil)
 		*hz = fasthz;
+	rdmsr(0x10, (vlong*)&tsc);
+	m->fastclock = tsc;
 	return tsc;
 }
 
diff --git a/pc/fns.h b/pc/fns.h
index bc16f44acde74b8b3c0e794a3ee3043f3f112fe8..4a5c6c3445973ba7b4dca13afc00fed74b9e2cd2 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -1,5 +1,8 @@
 #include "../port/portfns.h"
 
+void	loopbackintr(Ureg*);
+
+
 void	aamloop(int);
 void	addconf(char*, char*);
 //void	addscsilink(char*, Scsiio (*)(int, ISAConf*));
@@ -59,7 +62,6 @@ void	kbdinit(void);
 void	lgdt(ushort[3]);
 void	lidt(ushort[3]);
 void	links(void);
-void	loopbackintr(void);
 void	ltr(ulong);
 void	mathinit(void);
 void	meminit(ulong);
diff --git a/pc/i8253.c b/pc/i8253.c
index 6ae80cf3d8fda27d31e2f86f3e966aa7de829a33..3e5fdd28d99f5e59522422e8fe5d6bff88aa7382 100644
--- a/pc/i8253.c
+++ b/pc/i8253.c
@@ -13,19 +13,23 @@ enum
 	T0cntr=	0x40,		/* counter ports */
 	T1cntr=	0x41,		/* ... */
 	T2cntr=	0x42,		/* ... */
-	Tmode=	0x43,		/* mode port */
+	Tmode=	0x43,		/* mode port (control word register) */
 
 	/* commands */
 	Latch0=	0x00,		/* latch counter 0's value */
+	Load0l=	0x10,		/* load counter 0's lsb */
+	Load0m=	0x20,		/* load counter 0's msb */
 	Load0=	0x30,		/* load counter 0 with 2 bytes */
 
 	/* modes */
-	Square=	0x36,		/* periodic square wave */
-	Trigger= 0x30,		/* interrupt on terminal count */
+	Square=	0x6,		/* periodic square wave */
+	Trigger= 0x0,		/* interrupt on terminal count */
 
 	Freq=	1193182,	/* Real clock frequency */
 };
 
+static Lock	i8253lock;
+
 void
 i8253init(int aalcycles, int havecycleclock)
 {
@@ -124,10 +128,17 @@ i8253init(int aalcycles, int havecycleclock)
 	}
 }
 
+int
+i8253readcnt(void)
+{
+	ilock(&i8253lock);
+	iunlock(&i8253lock);
+}
+
 static void
 clockintr0(Ureg* ureg, void *v)
 {
-	loopbackintr();
+	loopbackintr(ureg);
 	clockintr(ureg, v);
 }