Initial import

1 files changed, 314 insertions, 0 deletions

diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
new file mode 100644
index 000000000..55feba7a5
--- /dev/null
+++ b/include/linux/jiffies.h
@@ -0,0 +1,314 @@
+#ifndef _LINUX_JIFFIES_H
+#define _LINUX_JIFFIES_H
+
+#include <linux/math64.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <asm/param.h>			/* for HZ */
+
+/*
+ * 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
+#elif HZ >= 1536 && HZ < 3072
+# define SHIFT_HZ	11
+#elif HZ >= 3072 && HZ < 6144
+# define SHIFT_HZ	12
+#elif HZ >= 6144 && HZ < 12288
+# define SHIFT_HZ	13
+#else
+# error Invalid value of HZ.
+#endif
+
+/* 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
+ * 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))
+
+/* LATCH is used in the interval timer and ftape setup. */
+#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ)	/* For divider */
+
+extern int register_refined_jiffies(long clock_tick_rate);
+
+/* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
+#define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)
+
+/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
+#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
+
+/* some arch's have a small-data section that can be accessed register-relative
+ * but that can only take up to, say, 4-byte variables. jiffies being part of
+ * an 8-byte variable may not be correctly accessed unless we force the issue
+ */
+#define __jiffy_data  __attribute__((section(".data")))
+
+/*
+ * The 64-bit value is not atomic - you MUST NOT read it
+ * without sampling the sequence number in jiffies_lock.
+ * get_jiffies_64() will do this for you as appropriate.
+ */
+extern u64 __jiffy_data jiffies_64;
+extern unsigned long volatile __jiffy_data jiffies;
+
+#if (BITS_PER_LONG < 64)
+u64 get_jiffies_64(void);
+#else
+static inline u64 get_jiffies_64(void)
+{
+	return (u64)jiffies;
+}
+#endif
+
+/*
+ *	These inlines deal with timer wrapping correctly. You are 
+ *	strongly encouraged to use them
+ *	1. Because people otherwise forget
+ *	2. Because if the timer wrap changes in future you won't have to
+ *	   alter your driver code.
+ *
+ * time_after(a,b) returns true if the time a is after time b.
+ *
+ * Do this with "<0" and ">=0" to only test the sign of the result. A
+ * good compiler would generate better code (and a really good compiler
+ * wouldn't care). Gcc is currently neither.
+ */
+#define time_after(a,b)		\
+	(typecheck(unsigned long, a) && \
+	 typecheck(unsigned long, b) && \
+	 ((long)((b) - (a)) < 0))
+#define time_before(a,b)	time_after(b,a)
+
+#define time_after_eq(a,b)	\
+	(typecheck(unsigned long, a) && \
+	 typecheck(unsigned long, b) && \
+	 ((long)((a) - (b)) >= 0))
+#define time_before_eq(a,b)	time_after_eq(b,a)
+
+/*
+ * Calculate whether a is in the range of [b, c].
+ */
+#define time_in_range(a,b,c) \
+	(time_after_eq(a,b) && \
+	 time_before_eq(a,c))
+
+/*
+ * Calculate whether a is in the range of [b, c).
+ */
+#define time_in_range_open(a,b,c) \
+	(time_after_eq(a,b) && \
+	 time_before(a,c))
+
+/* Same as above, but does so with platform independent 64bit types.
+ * These must be used when utilizing jiffies_64 (i.e. return value of
+ * get_jiffies_64() */
+#define time_after64(a,b)	\
+	(typecheck(__u64, a) &&	\
+	 typecheck(__u64, b) && \
+	 ((__s64)((b) - (a)) < 0))
+#define time_before64(a,b)	time_after64(b,a)
+
+#define time_after_eq64(a,b)	\
+	(typecheck(__u64, a) && \
+	 typecheck(__u64, b) && \
+	 ((__s64)((a) - (b)) >= 0))
+#define time_before_eq64(a,b)	time_after_eq64(b,a)
+
+#define time_in_range64(a, b, c) \
+	(time_after_eq64(a, b) && \
+	 time_before_eq64(a, c))
+
+/*
+ * These four macros compare jiffies and 'a' for convenience.
+ */
+
+/* time_is_before_jiffies(a) return true if a is before jiffies */
+#define time_is_before_jiffies(a) time_after(jiffies, a)
+
+/* time_is_after_jiffies(a) return true if a is after jiffies */
+#define time_is_after_jiffies(a) time_before(jiffies, a)
+
+/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
+#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
+
+/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
+#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
+
+/*
+ * Have the 32 bit jiffies value wrap 5 minutes after boot
+ * so jiffies wrap bugs show up earlier.
+ */
+#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-10*HZ))
+
+/*
+ * Change timeval to jiffies, trying to avoid the
+ * most obvious overflows..
+ *
+ * And some not so obvious.
+ *
+ * Note that we don't want to return LONG_MAX, because
+ * for various timeout reasons we often end up having
+ * to wait "jiffies+1" in order to guarantee that we wait
+ * at _least_ "jiffies" - so "jiffies+1" had better still
+ * be positive.
+ */
+#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)
+
+extern unsigned long preset_lpj;
+
+/*
+ * We want to do realistic conversions of time so we need to use the same
+ * values the update wall clock code uses as the jiffies size.  This value
+ * is: TICK_NSEC (which is defined in timex.h).  This
+ * is a constant and is in nanoseconds.  We will use scaled math
+ * with a set of scales defined here as SEC_JIFFIE_SC,  USEC_JIFFIE_SC and
+ * NSEC_JIFFIE_SC.  Note that these defines contain nothing but
+ * constants and so are computed at compile time.  SHIFT_HZ (computed in
+ * timex.h) adjusts the scaling for different HZ values.
+
+ * Scaled math???  What is that?
+ *
+ * Scaled math is a way to do integer math on values that would,
+ * otherwise, either overflow, underflow, or cause undesired div
+ * instructions to appear in the execution path.  In short, we "scale"
+ * up the operands so they take more bits (more precision, less
+ * underflow), do the desired operation and then "scale" the result back
+ * by the same amount.  If we do the scaling by shifting we avoid the
+ * costly mpy and the dastardly div instructions.
+
+ * Suppose, for example, we want to convert from seconds to jiffies
+ * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE.  The
+ * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We
+ * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we
+ * might calculate at compile time, however, the result will only have
+ * about 3-4 bits of precision (less for smaller values of HZ).
+ *
+ * So, we scale as follows:
+ * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);
+ * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;
+ * Then we make SCALE a power of two so:
+ * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;
+ * Now we define:
+ * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))
+ * jiff = (sec * SEC_CONV) >> SCALE;
+ *
+ * Often the math we use will expand beyond 32-bits so we tell C how to
+ * do this and pass the 64-bit result of the mpy through the ">> SCALE"
+ * which should take the result back to 32-bits.  We want this expansion
+ * to capture as much precision as possible.  At the same time we don't
+ * want to overflow so we pick the SCALE to avoid this.  In this file,
+ * that means using a different scale for each range of HZ values (as
+ * defined in timex.h).
+ *
+ * For those who want to know, gcc will give a 64-bit result from a "*"
+ * operator if the result is a long long AND at least one of the
+ * operands is cast to long long (usually just prior to the "*" so as
+ * not to confuse it into thinking it really has a 64-bit operand,
+ * which, buy the way, it can do, but it takes more code and at least 2
+ * mpys).
+
+ * We also need to be aware that one second in nanoseconds is only a
+ * couple of bits away from overflowing a 32-bit word, so we MUST use
+ * 64-bits to get the full range time in nanoseconds.
+
+ */
+
+/*
+ * Here are the scales we will use.  One for seconds, nanoseconds and
+ * microseconds.
+ *
+ * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and
+ * check if the sign bit is set.  If not, we bump the shift count by 1.
+ * (Gets an extra bit of precision where we can use it.)
+ * We know it is set for HZ = 1024 and HZ = 100 not for 1000.
+ * Haven't tested others.
+
+ * Limits of cpp (for #if expressions) only long (no long long), but
+ * then we only need the most signicant bit.
+ */
+
+#define SEC_JIFFIE_SC (31 - SHIFT_HZ)
+#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
+#undef SEC_JIFFIE_SC
+#define SEC_JIFFIE_SC (32 - SHIFT_HZ)
+#endif
+#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)
+#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\
+                                TICK_NSEC -1) / (u64)TICK_NSEC))
+
+#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\
+                                        TICK_NSEC -1) / (u64)TICK_NSEC))
+/*
+ * The maximum jiffie value is (MAX_INT >> 1).  Here we translate that
+ * into seconds.  The 64-bit case will overflow if we are not careful,
+ * so use the messy SH_DIV macro to do it.  Still all constants.
+ */
+#if BITS_PER_LONG < 64
+# define MAX_SEC_IN_JIFFIES \
+	(long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
+#else	/* take care of overflow on 64 bits machines */
+# define MAX_SEC_IN_JIFFIES \
+	(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)
+
+#endif
+
+/*
+ * Convert various time units to each other:
+ */
+extern unsigned int jiffies_to_msecs(const unsigned long j);
+extern unsigned int jiffies_to_usecs(const unsigned long j);
+
+static inline u64 jiffies_to_nsecs(const unsigned long j)
+{
+	return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
+}
+
+extern unsigned long msecs_to_jiffies(const unsigned int m);
+extern unsigned long usecs_to_jiffies(const unsigned int u);
+extern unsigned long timespec_to_jiffies(const struct timespec *value);
+extern void jiffies_to_timespec(const unsigned long jiffies,
+				struct timespec *value);
+extern unsigned long timeval_to_jiffies(const struct timeval *value);
+extern void jiffies_to_timeval(const unsigned long jiffies,
+			       struct timeval *value);
+
+extern clock_t jiffies_to_clock_t(unsigned long x);
+static inline clock_t jiffies_delta_to_clock_t(long delta)
+{
+	return jiffies_to_clock_t(max(0L, delta));
+}
+
+extern unsigned long clock_t_to_jiffies(unsigned long x);
+extern u64 jiffies_64_to_clock_t(u64 x);
+extern u64 nsec_to_clock_t(u64 x);
+extern u64 nsecs_to_jiffies64(u64 n);
+extern unsigned long nsecs_to_jiffies(u64 n);
+
+#define TIMESTAMP_SIZE	30
+
+#endif