From cb382d00f751c5d8a48d515b87a10bb24ddb3891 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 9 Jun 2002 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2002-06-09

---
 pc/fns.h   |  5 +++--
 pc/i8253.c | 38 ++++++++++++++++++++++++++++++++++++++
 pc/main.c  |  1 +
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/pc/fns.h b/pc/fns.h
index 54ea0a43804bf312f9e326be2ad9552d38a417f8..e9c1709bd4c5feb2cf066d1577cb3e07ac44b0f2 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -41,10 +41,11 @@ void	i8042reset(void);
 void	i8250console(void);
 void*	i8250alloc(int, int, int);
 void	i8250mouse(char*, int (*)(Queue*, int), int);
-void	i8253init(void);
 void	i8253enable(void);
-void	i8253timerset(uvlong);
+void	i8253init(void);
+void	i8253link(void);
 uvlong	i8253read(uvlong*);
+void	i8253timerset(uvlong);
 void	i8259init(void);
 int	i8259isr(int);
 int	i8259enable(Vctl*);
diff --git a/pc/i8253.c b/pc/i8253.c
index e13a455617e9e1fbfb3256ecb5209a366f31251c..63d21d13033fca7612faa2989cb6561c6fe4df96 100644
--- a/pc/i8253.c
+++ b/pc/i8253.c
@@ -186,6 +186,7 @@ guesscpuhz(int aalcycles)
 }
 
 ulong i8253periodset;
+int i8253dotimerset = 1;
 
 void
 i8253timerset(uvlong next)
@@ -194,6 +195,9 @@ i8253timerset(uvlong next)
 	ulong want;
 	ulong now;
 
+	if(i8253dotimerset == 0)
+		return;
+
 	want = next>>Tickshift;
 	now = i8253.ticks;	/* assuming whomever called us just did fastticks() */
 
@@ -235,6 +239,40 @@ i8253enable(void)
 	intrenable(IrqCLOCK, i8253clock, 0, BUSUNKNOWN, "clock");
 }
 
+static long
+i8253timerread(Chan*, void *a, long n, vlong offset)
+{
+	if(n < 16)
+		error("need more room");
+	if(offset)
+		return 0;
+	return snprint(a, n, "timerset %s", i8253dotimerset ? "on" : "off");
+}
+
+static long
+i8253timerwrite(Chan*, void *a, long n, vlong)
+{
+	if(n==3 && memcmp(a, "off", 3) == 0){
+		i8253dotimerset = 0;
+		outb(Tmode, Load0|Square);
+		outb(T0cntr, (Freq/HZ));
+		outb(T0cntr, (Freq/HZ)>>8);
+		return n;
+	}
+	if(n==2 && memcmp(a, "on", 2) == 0){
+		i8253dotimerset = 1;
+		return n;
+	}
+	error("invalid control message");
+	return -1;
+}
+
+void
+i8253link(void)
+{
+	addarchfile("i8253timerset", 0664, i8253timerread, i8253timerwrite);
+}
+
 /*
  *  return the total ticks of counter 1.  We shift by
  *  8 to give timesync more wriggle room for interpretation
diff --git a/pc/main.c b/pc/main.c
index a974090fabe25666aa71145cb548d28ec2170d3c..90e450771eab573b119e33f4236831b37d5f790a 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -105,6 +105,7 @@ main(void)
 	links();
 conf.monitor = 1;
 	chandevreset();
+	i8253link();
 	pageinit();
 	swapinit();
 	userinit();