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 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_JIFFIES_H
 #define _LINUX_JIFFIES_H
 
 #include <linux/cache.h>
 #include <linux/limits.h>
 #include <linux/math64.h>
 #include <linux/minmax.h>
 #include <linux/types.h>
 #include <linux/time.h>
 #include <linux/timex.h>
 #include <vdso/jiffies.h>
 #include <asm/param.h>          /* for HZ */
 #include <generated/timeconst.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
 #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_USEC is the time between ticks in usec assuming SHIFTED_HZ */
 #define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ)
 
 /* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
 #define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
 
 #ifndef __jiffy_arch_data
 #define __jiffy_arch_data
 #endif
 
 /*
  * 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 __cacheline_aligned_in_smp jiffies_64;
 extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_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)
 #define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a)
 
 /* time_is_after_jiffies(a) return true if a is after jiffies */
 #define time_is_after_jiffies(a) time_before(jiffies, a)
 #define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), 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)
 #define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), 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)
 #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), 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) (-300*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 u64 jiffies64_to_nsecs(u64 j);
 extern u64 jiffies64_to_msecs(u64 j);
 
 extern unsigned long __msecs_to_jiffies(const unsigned int m);
 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
 /*
  * HZ is equal to or smaller than 1000, and 1000 is a nice round
  * multiple of HZ, divide with the factor between them, but round
  * upwards:
  */
 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
 {
     return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
 }
 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
 /*
  * HZ is larger than 1000, and HZ is a nice round multiple of 1000 -
  * simply multiply with the factor between them.
  *
  * But first make sure the multiplication result cannot overflow:
  */
 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
 {
     if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
         return MAX_JIFFY_OFFSET;
     return m * (HZ / MSEC_PER_SEC);
 }
 #else
 /*
  * Generic case - multiply, round and divide. But first check that if
  * we are doing a net multiplication, that we wouldn't overflow:
  */
 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
 {
     if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
         return MAX_JIFFY_OFFSET;
 
     return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32;
 }
 #endif
 /**
  * msecs_to_jiffies: - convert milliseconds to jiffies
  * @m:  time in milliseconds
  *
  * conversion is done as follows:
  *
  * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
  *
  * - 'too large' values [that would result in larger than
  *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
  *
  * - all other values are converted to jiffies by either multiplying
  *   the input value by a factor or dividing it with a factor and
  *   handling any 32-bit overflows.
  *   for the details see __msecs_to_jiffies()
  *
  * msecs_to_jiffies() checks for the passed in value being a constant
  * via __builtin_constant_p() allowing gcc to eliminate most of the
  * code, __msecs_to_jiffies() is called if the value passed does not
  * allow constant folding and the actual conversion must be done at
  * runtime.
  * the HZ range specific helpers _msecs_to_jiffies() are called both
  * directly here and from __msecs_to_jiffies() in the case where
  * constant folding is not possible.
  */
 static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
 {
     if (__builtin_constant_p(m)) {
         if ((int)m < 0)
             return MAX_JIFFY_OFFSET;
         return _msecs_to_jiffies(m);
     } else {
         return __msecs_to_jiffies(m);
     }
 }
 
 extern unsigned long __usecs_to_jiffies(const unsigned int u);
 #if !(USEC_PER_SEC % HZ)
 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
 {
     return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
 }
 #else
 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
 {
     return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
         >> USEC_TO_HZ_SHR32;
 }
 #endif
 
 /**
  * usecs_to_jiffies: - convert microseconds to jiffies
  * @u:  time in microseconds
  *
  * conversion is done as follows:
  *
  * - 'too large' values [that would result in larger than
  *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
  *
  * - all other values are converted to jiffies by either multiplying
  *   the input value by a factor or dividing it with a factor and
  *   handling any 32-bit overflows as for msecs_to_jiffies.
  *
  * usecs_to_jiffies() checks for the passed in value being a constant
  * via __builtin_constant_p() allowing gcc to eliminate most of the
  * code, __usecs_to_jiffies() is called if the value passed does not
  * allow constant folding and the actual conversion must be done at
  * runtime.
  * the HZ range specific helpers _usecs_to_jiffies() are called both
  * directly here and from __msecs_to_jiffies() in the case where
  * constant folding is not possible.
  */
 static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
 {
     if (__builtin_constant_p(u)) {
         if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
             return MAX_JIFFY_OFFSET;
         return _usecs_to_jiffies(u);
     } else {
         return __usecs_to_jiffies(u);
     }
 }
 
 extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
 extern void jiffies_to_timespec64(const unsigned long jiffies,
                   struct timespec64 *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));
 }
 
 static inline unsigned int jiffies_delta_to_msecs(long delta)
 {
     return jiffies_to_msecs(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

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