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plan9: use _tos->cyclefreq instead of reading /dev/time

--- a/plan9.c

+++ b/plan9.c

@@ -9,6 +9,7 @@

 #include <thread.h>

 #include <plumb.h>

 #include <cursor.h>

+#include <tos.h>

 #define MIN(x,y) ((x)<=(y)?(x):(y))

 #define MAX(x,y) ((x)>=(y)?(x):(y))

@@ -517,41 +518,21 @@

  * nsec() is wallclock and can be adjusted by timesync

  * so need to use cycles() instead, but fall back to

  * nsec() in case we can't

- *

- * "fasthz" is how many ticks there are in a second

- * can be read from /dev/time

- *

- * perhaps using RDTSCP is even better

  */

-static uvlong

+uvlong

 nanosec(void)

 {

 	static uvlong fasthz, xstart;

 	uvlong x, div;

-	int f, n, i;

-	char tmp[128], *e;

-	if (fasthz == ~0ULL)

+	if(fasthz == ~0ULL)

 		return nsec() - xstart;

-	if (fasthz == 0) {

-		fasthz = ~0ULL;

+	if(fasthz == 0){

 		xstart = nsec();

-		if (usensec)

-			return 0;

-		if ((f = open("/dev/time", OREAD)) >= 0 && (n = read(f, tmp, sizeof(tmp)-1)) > 2) {

-			tmp[n] = 0;

-			e = tmp;

-			for (i = 0; i < 3; i++)

-				strtoll(e, &e, 10);

-			if ((fasthz = strtoll(e, nil, 10)) < 1)

-				fasthz = ~0ULL;

-			else

-				cycles(&xstart);

-		}

-		close(f);

-		if (fasthz == ~0ULL) {

-			fprint(2, "couldn't get fasthz, falling back to nsec()\n");

+		if((fasthz = _tos->cyclefreq) == 0){

+			fasthz = ~0ULL;

+			fprint(2, "cyclefreq not available, falling back to nsec()\n");

 			fprint(2, "you might want to disable aux/timesync\n");

 			return 0;

 		}

@@ -559,7 +540,8 @@

 	cycles(&x);

 	x -= xstart;

-	for (div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

+	/* this is ugly */

+	for(div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

 	return x / (fasthz / div);

 }