1 #ifndef _LINUX_JIFFIES_H
2 #define _LINUX_JIFFIES_H
4 #include <linux/kernel.h>
5 #include <linux/time64.h>
6 #include <linux/typecheck.h>
7 #include <linux/types.h>
11 #define MSEC_PER_SEC 1000L
12 #define USEC_PER_MSEC 1000L
13 #define NSEC_PER_USEC 1000L
14 #define NSEC_PER_MSEC 1000000L
15 #define USEC_PER_SEC 1000000L
16 #define NSEC_PER_SEC 1000000000L
17 #define FSEC_PER_SEC 1000000000000000LL
20 * The following defines establish the engineering parameters of the PLL
21 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
22 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
23 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
24 * nearest power of two in order to avoid hardware multiply operations.
26 #if HZ >= 12 && HZ < 24
28 #elif HZ >= 24 && HZ < 48
30 #elif HZ >= 48 && HZ < 96
32 #elif HZ >= 96 && HZ < 192
34 #elif HZ >= 192 && HZ < 384
36 #elif HZ >= 384 && HZ < 768
38 #elif HZ >= 768 && HZ < 1536
40 #elif HZ >= 1536 && HZ < 3072
42 #elif HZ >= 3072 && HZ < 6144
44 #elif HZ >= 6144 && HZ < 12288
47 # error Invalid value of HZ.
50 /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
51 * improve accuracy by shifting LSH bits, hence calculating:
53 * This however means trouble for large NOM, because (NOM << LSH) may no
54 * longer fit in 32 bits. The following way of calculating this gives us
55 * some slack, under the following conditions:
56 * - (NOM / DEN) fits in (32 - LSH) bits.
57 * - (NOM % DEN) fits in (32 - LSH) bits.
59 #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
60 + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
62 /* LATCH is used in the interval timer and ftape setup. */
63 #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
65 extern int register_refined_jiffies(long clock_tick_rate);
67 /* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
68 #define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)
70 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
71 #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
73 static inline u64 local_clock(void)
77 clock_gettime(CLOCK_MONOTONIC, &ts);
79 return ((s64) ts.tv_sec * NSEC_PER_SEC) + ts.tv_nsec;
82 extern unsigned long clock_t_to_jiffies(unsigned long x);
83 extern u64 jiffies_64_to_clock_t(u64 x);
84 extern u64 nsec_to_clock_t(u64 x);
85 extern u64 nsecs_to_jiffies64(u64 n);
86 extern unsigned long nsecs_to_jiffies(u64 n);
88 static inline u64 get_jiffies_64(void)
90 return nsecs_to_jiffies64(local_clock());
93 #define jiffies_64 get_jiffies_64()
94 #define jiffies ((unsigned long) get_jiffies_64())
97 * These inlines deal with timer wrapping correctly. You are
98 * strongly encouraged to use them
99 * 1. Because people otherwise forget
100 * 2. Because if the timer wrap changes in future you won't have to
101 * alter your driver code.
103 * time_after(a,b) returns true if the time a is after time b.
105 * Do this with "<0" and ">=0" to only test the sign of the result. A
106 * good compiler would generate better code (and a really good compiler
107 * wouldn't care). Gcc is currently neither.
109 #define time_after(a,b) \
110 (typecheck(unsigned long, a) && \
111 typecheck(unsigned long, b) && \
112 ((long)((b) - (a)) < 0))
113 #define time_before(a,b) time_after(b,a)
115 #define time_after_eq(a,b) \
116 (typecheck(unsigned long, a) && \
117 typecheck(unsigned long, b) && \
118 ((long)((a) - (b)) >= 0))
119 #define time_before_eq(a,b) time_after_eq(b,a)
122 * Calculate whether a is in the range of [b, c].
124 #define time_in_range(a,b,c) \
125 (time_after_eq(a,b) && \
129 * Calculate whether a is in the range of [b, c).
131 #define time_in_range_open(a,b,c) \
132 (time_after_eq(a,b) && \
135 /* Same as above, but does so with platform independent 64bit types.
136 * These must be used when utilizing jiffies_64 (i.e. return value of
137 * get_jiffies_64() */
138 #define time_after64(a,b) \
139 (typecheck(__u64, a) && \
140 typecheck(__u64, b) && \
141 ((__s64)((b) - (a)) < 0))
142 #define time_before64(a,b) time_after64(b,a)
144 #define time_after_eq64(a,b) \
145 (typecheck(__u64, a) && \
146 typecheck(__u64, b) && \
147 ((__s64)((a) - (b)) >= 0))
148 #define time_before_eq64(a,b) time_after_eq64(b,a)
150 #define time_in_range64(a, b, c) \
151 (time_after_eq64(a, b) && \
152 time_before_eq64(a, c))
155 * These four macros compare jiffies and 'a' for convenience.
158 /* time_is_before_jiffies(a) return true if a is before jiffies */
159 #define time_is_before_jiffies(a) time_after(jiffies, a)
161 /* time_is_after_jiffies(a) return true if a is after jiffies */
162 #define time_is_after_jiffies(a) time_before(jiffies, a)
164 /* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
165 #define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
167 /* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
168 #define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
171 * Have the 32 bit jiffies value wrap 5 minutes after boot
172 * so jiffies wrap bugs show up earlier.
174 #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
177 * Change timeval to jiffies, trying to avoid the
178 * most obvious overflows..
180 * And some not so obvious.
182 * Note that we don't want to return LONG_MAX, because
183 * for various timeout reasons we often end up having
184 * to wait "jiffies+1" in order to guarantee that we wait
185 * at _least_ "jiffies" - so "jiffies+1" had better still
188 #define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)
190 extern unsigned long preset_lpj;
193 * We want to do realistic conversions of time so we need to use the same
194 * values the update wall clock code uses as the jiffies size. This value
195 * is: TICK_NSEC (which is defined in timex.h). This
196 * is a constant and is in nanoseconds. We will use scaled math
197 * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and
198 * NSEC_JIFFIE_SC. Note that these defines contain nothing but
199 * constants and so are computed at compile time. SHIFT_HZ (computed in
200 * timex.h) adjusts the scaling for different HZ values.
202 * Scaled math??? What is that?
204 * Scaled math is a way to do integer math on values that would,
205 * otherwise, either overflow, underflow, or cause undesired div
206 * instructions to appear in the execution path. In short, we "scale"
207 * up the operands so they take more bits (more precision, less
208 * underflow), do the desired operation and then "scale" the result back
209 * by the same amount. If we do the scaling by shifting we avoid the
210 * costly mpy and the dastardly div instructions.
212 * Suppose, for example, we want to convert from seconds to jiffies
213 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The
214 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We
215 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we
216 * might calculate at compile time, however, the result will only have
217 * about 3-4 bits of precision (less for smaller values of HZ).
219 * So, we scale as follows:
220 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);
221 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;
222 * Then we make SCALE a power of two so:
223 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;
225 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))
226 * jiff = (sec * SEC_CONV) >> SCALE;
228 * Often the math we use will expand beyond 32-bits so we tell C how to
229 * do this and pass the 64-bit result of the mpy through the ">> SCALE"
230 * which should take the result back to 32-bits. We want this expansion
231 * to capture as much precision as possible. At the same time we don't
232 * want to overflow so we pick the SCALE to avoid this. In this file,
233 * that means using a different scale for each range of HZ values (as
234 * defined in timex.h).
236 * For those who want to know, gcc will give a 64-bit result from a "*"
237 * operator if the result is a long long AND at least one of the
238 * operands is cast to long long (usually just prior to the "*" so as
239 * not to confuse it into thinking it really has a 64-bit operand,
240 * which, buy the way, it can do, but it takes more code and at least 2
243 * We also need to be aware that one second in nanoseconds is only a
244 * couple of bits away from overflowing a 32-bit word, so we MUST use
245 * 64-bits to get the full range time in nanoseconds.
250 * Here are the scales we will use. One for seconds, nanoseconds and
253 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and
254 * check if the sign bit is set. If not, we bump the shift count by 1.
255 * (Gets an extra bit of precision where we can use it.)
256 * We know it is set for HZ = 1024 and HZ = 100 not for 1000.
257 * Haven't tested others.
259 * Limits of cpp (for #if expressions) only long (no long long), but
260 * then we only need the most signicant bit.
263 #define SEC_JIFFIE_SC (31 - SHIFT_HZ)
264 #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
266 #define SEC_JIFFIE_SC (32 - SHIFT_HZ)
268 #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)
269 #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\
270 TICK_NSEC -1) / (u64)TICK_NSEC))
272 #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\
273 TICK_NSEC -1) / (u64)TICK_NSEC))
275 * The maximum jiffie value is (MAX_INT >> 1). Here we translate that
276 * into seconds. The 64-bit case will overflow if we are not careful,
277 * so use the messy SH_DIV macro to do it. Still all constants.
279 #if BITS_PER_LONG < 64
280 # define MAX_SEC_IN_JIFFIES \
281 (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
282 #else /* take care of overflow on 64 bits machines */
283 # define MAX_SEC_IN_JIFFIES \
284 (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)
289 * Convert various time units to each other:
291 extern unsigned int jiffies_to_msecs(const unsigned long j);
292 extern unsigned int jiffies_to_usecs(const unsigned long j);
294 static inline u64 jiffies_to_nsecs(const unsigned long j)
296 return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
299 extern unsigned long __msecs_to_jiffies(const unsigned int m);
300 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
302 * HZ is equal to or smaller than 1000, and 1000 is a nice round
303 * multiple of HZ, divide with the factor between them, but round
306 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
308 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
310 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
312 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 -
313 * simply multiply with the factor between them.
315 * But first make sure the multiplication result cannot overflow:
317 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
319 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
320 return MAX_JIFFY_OFFSET;
321 return m * (HZ / MSEC_PER_SEC);
325 * Generic case - multiply, round and divide. But first check that if
326 * we are doing a net multiplication, that we wouldn't overflow:
328 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
330 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
331 return MAX_JIFFY_OFFSET;
333 return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32;
337 * msecs_to_jiffies: - convert milliseconds to jiffies
338 * @m: time in milliseconds
340 * conversion is done as follows:
342 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
344 * - 'too large' values [that would result in larger than
345 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
347 * - all other values are converted to jiffies by either multiplying
348 * the input value by a factor or dividing it with a factor and
349 * handling any 32-bit overflows.
350 * for the details see __msecs_to_jiffies()
352 * msecs_to_jiffies() checks for the passed in value being a constant
353 * via __builtin_constant_p() allowing gcc to eliminate most of the
354 * code, __msecs_to_jiffies() is called if the value passed does not
355 * allow constant folding and the actual conversion must be done at
357 * the HZ range specific helpers _msecs_to_jiffies() are called both
358 * directly here and from __msecs_to_jiffies() in the case where
359 * constant folding is not possible.
361 static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
363 if (__builtin_constant_p(m)) {
365 return MAX_JIFFY_OFFSET;
366 return _msecs_to_jiffies(m);
368 return __msecs_to_jiffies(m);
372 extern unsigned long __usecs_to_jiffies(const unsigned int u);
373 #if !(USEC_PER_SEC % HZ)
374 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
376 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
379 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
381 return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
387 * usecs_to_jiffies: - convert microseconds to jiffies
388 * @u: time in microseconds
390 * conversion is done as follows:
392 * - 'too large' values [that would result in larger than
393 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
395 * - all other values are converted to jiffies by either multiplying
396 * the input value by a factor or dividing it with a factor and
397 * handling any 32-bit overflows as for msecs_to_jiffies.
399 * usecs_to_jiffies() checks for the passed in value being a constant
400 * via __builtin_constant_p() allowing gcc to eliminate most of the
401 * code, __usecs_to_jiffies() is called if the value passed does not
402 * allow constant folding and the actual conversion must be done at
404 * the HZ range specific helpers _usecs_to_jiffies() are called both
405 * directly here and from __msecs_to_jiffies() in the case where
406 * constant folding is not possible.
408 static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
410 if (__builtin_constant_p(u)) {
411 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
412 return MAX_JIFFY_OFFSET;
413 return _usecs_to_jiffies(u);
415 return __usecs_to_jiffies(u);
419 extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
421 extern void jiffies_to_timespec64(const unsigned long,
422 struct timespec64 *value);
423 static inline unsigned long timespec_to_jiffies(const struct timespec *value)
425 struct timespec64 ts = timespec_to_timespec64(*value);
427 return timespec64_to_jiffies(&ts);
430 static inline void jiffies_to_timespec(const unsigned long j,
431 struct timespec *value)
433 struct timespec64 ts;
435 jiffies_to_timespec64(j, &ts);
436 *value = timespec64_to_timespec(ts);
439 extern unsigned long timeval_to_jiffies(const struct timeval *value);
440 extern void jiffies_to_timeval(const unsigned long j,
441 struct timeval *value);
443 extern clock_t jiffies_to_clock_t(unsigned long x);
444 static inline clock_t jiffies_delta_to_clock_t(long delta)
446 return jiffies_to_clock_t(max(0L, delta));
449 #define TIMESTAMP_SIZE 30