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/* SPDX-License-Identifier: GPL-2.0 / #ifndef _LINUX_JIFFIES_H #define _LINUX_JIFFIES_H #include <linux/cache.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 / #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_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 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) (-300HZ)) /* * 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); static inline unsigned long timespec_to_jiffies(const struct timespec value) { struct timespec64 ts = timespec_to_timespec64(value); return timespec64_to_jiffies(&ts); } static inline void jiffies_to_timespec(const unsigned long jiffies, struct timespec value) { struct timespec64 ts; jiffies_to_timespec64(jiffies, &ts); value = timespec64_to_timespec(ts); } 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)); } 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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