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[linux-2.6.git] / include / linux / timex.h

diff --git a/include/linux/timex.h b/include/linux/timex.h
index b54c288..ee8cafa 100644 (file)
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -55,10 +55,33 @@
 
 #include <linux/config.h>
 #include <linux/compiler.h>
-#include <linux/time.h>
 
 #include <asm/param.h>
-#include <asm/timex.h>
+
+/*
+ * The following defines establish the engineering parameters of the PLL
+ * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
+ * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
+ * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
+ * nearest power of two in order to avoid hardware multiply operations.
+ */
+#if HZ >= 12 && HZ < 24
+# define SHIFT_HZ      4
+#elif HZ >= 24 && HZ < 48
+# define SHIFT_HZ      5
+#elif HZ >= 48 && HZ < 96
+# define SHIFT_HZ      6
+#elif HZ >= 96 && HZ < 192
+# define SHIFT_HZ      7
+#elif HZ >= 192 && HZ < 384
+# define SHIFT_HZ      8
+#elif HZ >= 384 && HZ < 768
+# define SHIFT_HZ      9
+#elif HZ >= 768 && HZ < 1536
+# define SHIFT_HZ      10
+#else
+# error You lose.
+#endif
 
 /*
  * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
@@ -128,6 +151,41 @@
 #define PPS_VALID 120          /* pps signal watchdog max (s) */
 #define MAXGLITCH 30           /* pps signal glitch max (s) */
 
+/*
+ * Pick up the architecture specific timex specifications
+ */
+#include <asm/timex.h>
+
+/* LATCH is used in the interval timer and ftape setup. */
+#define LATCH  ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
+
+/* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, the we can
+ * improve accuracy by shifting LSH bits, hence calculating:
+ *     (NOM << LSH) / DEN
+ * This however means trouble for large NOM, because (NOM << LSH) may no
+ * longer fit in 32 bits. The following way of calculating this gives us
+ * some slack, under the following conditions:
+ *   - (NOM / DEN) fits in (32 - LSH) bits.
+ *   - (NOM % DEN) fits in (32 - LSH) bits.
+ */
+#define SH_DIV(NOM,DEN,LSH) (   ((NOM / DEN) << LSH)                    \
+                             + (((NOM % DEN) << LSH) + DEN / 2) / DEN)
+
+/* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */
+#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))
+
+/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */
+#define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8))
+
+/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
+#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
+
+/* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and */
+/* a value TUSEC for TICK_USEC (can be set bij adjtimex)               */
+#define TICK_USEC_TO_NSEC(TUSEC) (SH_DIV (TUSEC * USER_HZ * 1000, ACTHZ, 8))
+
+
+#include <linux/time.h>
 /*
  * syscall interface - used (mainly by NTP daemon)
  * to discipline kernel clock oscillator