summaryrefslogtreecommitdiff
path: root/include/linux/jiffies.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/jiffies.h')
-rw-r--r--include/linux/jiffies.h12
1 files changed, 8 insertions, 4 deletions
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 265e2c3cbd1c..7d24466fb80b 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -39,9 +39,6 @@
# error Invalid value of HZ.
#endif
-/* LATCH is used in the interval timer and ftape setup. */
-#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
-
/* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
* improve accuracy by shifting LSH bits, hence calculating:
* (NOM << LSH) / DEN
@@ -54,8 +51,15 @@
#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
+ ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
+#ifdef CLOCK_TICK_RATE
+/* LATCH is used in the interval timer and ftape setup. */
+# define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
+
/* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */
-#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))
+# define ACTHZ (SH_DIV(CLOCK_TICK_RATE, LATCH, 8))
+#else
+# define ACTHZ (HZ << 8)
+#endif
/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */
#define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8))