From d6a2825ae408609301329df4abbdb22fb324ecc1 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Fri, 10 Jul 1998 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1998-07-10

---
 ip/devip.c       |  2 +-
 pc/archgeneric.c | 38 ++++++++++++++++++++++++++++++++++++++
 pc/clock.c       |  1 +
 pc/dat.h         |  1 +
 pc/fns.h         |  1 +
 pc/i8253.c       | 14 ++++++++++++++
 port/devcons.c   | 31 +++++++++++++++++++++++++++++++
 port/portfns.h   |  1 +
 8 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/ip/devip.c b/ip/devip.c
index 7814d43eab2f0597f133d8e3699e597b826d9a0e..bfbc364f06864db29d91d4e18d8569a58d11624b 100644
--- a/ip/devip.c
+++ b/ip/devip.c
@@ -520,7 +520,7 @@ ipread(Chan *ch, void *a, long n, vlong off)
 	Conv *c;
 	Proto *x;
 	char *buf, *p;
-	long m, rv;
+	long rv;
 	Fs *f;
 	ulong offset = off;
 
diff --git a/pc/archgeneric.c b/pc/archgeneric.c
index d2945c0cd4e557be9eb17a9b43ffea61a44d517e..561b33b13e17505b3734354bd5a3f63d33002a4b 100644
--- a/pc/archgeneric.c
+++ b/pc/archgeneric.c
@@ -17,6 +17,8 @@ nop(void)
 }
 
 void (*coherence)(void) = nop;
+void cycletimerinit(void);
+uvlong cycletimer(uvlong*);
 
 PCArch* arch;
 extern PCArch* knownarch[];
@@ -32,6 +34,8 @@ PCArch archgeneric = {
 	i8259enable,				/* intrenable */
 
 	i8253enable,				/* clockenable */
+
+	i8253read,				/* read the standard timer */
 };
 
 typedef struct {
@@ -185,6 +189,12 @@ archinit(void)
 			arch->intrenable = archgeneric.intrenable;
 	}
 
+	/* pick the better timer */
+	if(X86FAMILY(m->cpuidax) >= 5){
+		cycletimerinit();
+		arch->fastclock = cycletimer;
+	}
+
 	/*
 	 * Decide whether to use copy-on-reference (386 and mp).
 	 */
@@ -194,3 +204,31 @@ archinit(void)
 	if(X86FAMILY(m->cpuidax) == 6 /*&& conf.nmach > 1*/)
 		coherence = wbflush;
 }
+
+static uvlong fasthz;
+
+void
+cycletimerinit(void)
+{
+	fasthz = 1000000LL*m->cpumhz;
+}
+
+/*
+ *  return the most precice clock we have
+ */
+uvlong
+cycletimer(uvlong *hz)
+{
+	uvlong tsc;
+
+	rdmsr(0x10, (vlong*)&tsc);
+	if(hz != nil)
+		*hz = fasthz;
+	return tsc;
+}
+
+uvlong
+fastticks(uvlong *hz)
+{
+	return (*arch->fastclock)(hz);
+}
diff --git a/pc/clock.c b/pc/clock.c
index 0e21e510bc328df03af8e492ead8d432ba5d9847..3954a5bec32f4a8df34a225f291b2d580205966a 100644
--- a/pc/clock.c
+++ b/pc/clock.c
@@ -88,3 +88,4 @@ microdelay(int microsecs)
 		microsecs = 1;
 	aamloop(microsecs);
 }
+
diff --git a/pc/dat.h b/pc/dat.h
index b4d22fed551cc980806dcef5588a46ea9d7fd1c1..957c2325564254d62c437a7a139e1d431f624d50 100644
--- a/pc/dat.h
+++ b/pc/dat.h
@@ -221,6 +221,7 @@ struct PCArch
 	int	(*intrenable)(int, int, Irqctl*);
 
 	void	(*clockenable)(void);
+	uvlong	(*fastclock)(uvlong*);
 };
 
 /*
diff --git a/pc/fns.h b/pc/fns.h
index 4a47e89f539ddbf1f5b22b3e760db5b36e692c53..bd3ec3c5f0ad9c9ffbb1e093f424baaf1a1bbd5b 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -36,6 +36,7 @@ void	i8042auxenable(void (*)(int, int));
 void	i8042reset(void);
 void	i8253init(int);
 void	i8253enable(void);
+uvlong	i8253read(uvlong*);
 void	i8259init(void);
 int	i8259enable(int, int, Irqctl*);
 void	idle(void);
diff --git a/pc/i8253.c b/pc/i8253.c
index 0326a6551d002f90f8676db6d91a05b09ab826e7..0ce67e8064d3dc371175e5c96cf6e880a1d50049 100644
--- a/pc/i8253.c
+++ b/pc/i8253.c
@@ -98,3 +98,17 @@ i8253enable(void)
 {
 	intrenable(VectorCLOCK, clockintr, 0, BUSUNKNOWN);
 }
+
+Lock i8253lock;
+
+/*
+ *  return time elapsed since clock start in
+ *  10ths of nanoseconds
+ */
+uvlong
+i8253read(uvlong *hz)
+{
+	if(hz)
+		*hz = HZ;
+	return m->ticks;
+}
diff --git a/port/devcons.c b/port/devcons.c
index de7c8f920573db5a65627031145060f752049349..5fa0c598fe6914e9aedcbf80692ebf9fe0e43e60 100644
--- a/port/devcons.c
+++ b/port/devcons.c
@@ -345,6 +345,7 @@ enum{
 	Qconsctl,
 	Qcputime,
 	Qdrivers,
+	Qfastclock,
 	Qhz,
 	Qkey,
 	Qhostdomain,
@@ -373,6 +374,7 @@ static Dirtab consdir[]={
 	"consctl",	{Qconsctl},	0,		0220,
 	"cputime",	{Qcputime},	6*NUMSIZE,	0444,
 	"drivers",	{Qdrivers},	0,		0644,
+	"fastclock",	{Qfastclock},	4*NUMSIZE,	0444,
 	"hostdomain",	{Qhostdomain},	DOMLEN,		0664,
 	"hostowner",	{Qhostowner},	NAMELEN,	0664,
 	"hz",		{Qhz},		NUMSIZE,	0666,
@@ -400,6 +402,21 @@ seconds(void)
 	return boottime + TK2SEC(MACHP(0)->ticks);
 }
 
+int
+readvlnum(ulong off, char *buf, ulong n, uvlong val, int size)
+{
+	char tmp[64];
+
+	snprint(tmp, sizeof(tmp), "%*.0ulld", size-1, val);
+	tmp[size-1] = ' ';
+	if(off >= size)
+		return 0;
+	if(off+n > size)
+		n = size-off;
+	memmove(buf, tmp+off, n);
+	return n;
+}
+
 int
 readnum(ulong off, char *buf, ulong n, ulong val, int size)
 {
@@ -515,6 +532,7 @@ consread(Chan *c, void *buf, long n, vlong off)
 	char *cbuf = buf;
 	int ch, i, k, id, eol;
 	vlong offset = off;
+	uvlong ticks, fasthz;
 
 	if(n <= 0)
 		return n;
@@ -623,6 +641,19 @@ consread(Chan *c, void *buf, long n, vlong off)
 		memmove(buf, tmp+k, n);
 		return n;
 
+	case Qfastclock:
+		ticks = fastticks(&fasthz);
+
+		k = offset;
+		if(k >= 4*NUMSIZE)
+			return 0;
+		if(k+n > 4*NUMSIZE)
+			n = 4*NUMSIZE - k;
+		readvlnum(0, tmp, 2*NUMSIZE, ticks, 2*NUMSIZE);
+		readvlnum(0, tmp+2*NUMSIZE, 2*NUMSIZE, fasthz, 2*NUMSIZE);
+		memmove(buf, tmp+k, n);
+		return n;
+
 	case Qkey:
 		return keyread(buf, n, offset);
 
diff --git a/port/portfns.h b/port/portfns.h
index 4b442324d11e0d60af37e550631eb2439af36658..7a1a033e8cbb02e9b4b052cda42ae786cfe82d48 100644
--- a/port/portfns.h
+++ b/port/portfns.h
@@ -91,6 +91,7 @@ void		error(char*);
 long		execregs(ulong, ulong, ulong);
 void		exhausted(char*);
 void		exit(int);
+uvlong		fastticks(uvlong*);
 int		fault(ulong, int);
 void		fdclose(int, int);
 Chan*		fdtochan(int, int, int, int);