1 #ifndef _LINUX_JIFFIES_H
2 #define _LINUX_JIFFIES_H
3
4 #include <linux/cache.h>
5 #include <linux/math64.h>
6 #include <linux/kernel.h>
7 #include <linux/types.h>
8 #include <linux/time.h>
9 #include <linux/timex.h>
10 #include <asm/param.h> /* for HZ */
11 #include <generated/timeconst.h>
12
13 /*
14 * The following defines establish the engineering parameters of the PLL
15 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
16 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
17 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
18 * nearest power of two in order to avoid hardware multiply operations.
19 */
20 #if HZ >= 12 && HZ < 24
21 # define SHIFT_HZ 4
22 #elif HZ >= 24 && HZ < 48
23 # define SHIFT_HZ 5
24 #elif HZ >= 48 && HZ < 96
25 # define SHIFT_HZ 6
26 #elif HZ >= 96 && HZ < 192
27 # define SHIFT_HZ 7
28 #elif HZ >= 192 && HZ < 384
29 # define SHIFT_HZ 8
30 #elif HZ >= 384 && HZ < 768
31 # define SHIFT_HZ 9
32 #elif HZ >= 768 && HZ < 1536
33 # define SHIFT_HZ 10
34 #elif HZ >= 1536 && HZ < 3072
35 # define SHIFT_HZ 11
36 #elif HZ >= 3072 && HZ < 6144
37 # define SHIFT_HZ 12
38 #elif HZ >= 6144 && HZ < 12288
39 # define SHIFT_HZ 13
40 #else
41 # error Invalid value of HZ.
42 #endif
43
44 /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
45 * improve accuracy by shifting LSH bits, hence calculating:
46 * (NOM << LSH) / DEN
47 * This however means trouble for large NOM, because (NOM << LSH) may no
48 * longer fit in 32 bits. The following way of calculating this gives us
49 * some slack, under the following conditions:
50 * - (NOM / DEN) fits in (32 - LSH) bits.
51 * - (NOM % DEN) fits in (32 - LSH) bits.
52 */
53 #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
54 + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
55
56 /* LATCH is used in the interval timer and ftape setup. */
57 #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
58
59 extern int register_refined_jiffies(long clock_tick_rate);
60
61 /* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
62 #define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)
63
64 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
65 #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
66
67 #ifndef __jiffy_arch_data
68 #define __jiffy_arch_data
69 #endif
70
71 /*
72 * The 64-bit value is not atomic - you MUST NOT read it
73 * without sampling the sequence number in jiffies_lock.
74 * get_jiffies_64() will do this for you as appropriate.
75 */
76 extern u64 __cacheline_aligned_in_smp jiffies_64;
77 extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies;
78
79 #if (BITS_PER_LONG < 64)
80 u64 get_jiffies_64(void);
81 #else
get_jiffies_64(void)82 static inline u64 get_jiffies_64(void)
83 {
84 return (u64)jiffies;
85 }
86 #endif
87
88 /*
89 * These inlines deal with timer wrapping correctly. You are
90 * strongly encouraged to use them
91 * 1. Because people otherwise forget
92 * 2. Because if the timer wrap changes in future you won't have to
93 * alter your driver code.
94 *
95 * time_after(a,b) returns true if the time a is after time b.
96 *
97 * Do this with "<0" and ">=0" to only test the sign of the result. A
98 * good compiler would generate better code (and a really good compiler
99 * wouldn't care). Gcc is currently neither.
100 */
101 #define time_after(a,b) \
102 (typecheck(unsigned long, a) && \
103 typecheck(unsigned long, b) && \
104 ((long)((b) - (a)) < 0))
105 #define time_before(a,b) time_after(b,a)
106
107 #define time_after_eq(a,b) \
108 (typecheck(unsigned long, a) && \
109 typecheck(unsigned long, b) && \
110 ((long)((a) - (b)) >= 0))
111 #define time_before_eq(a,b) time_after_eq(b,a)
112
113 /*
114 * Calculate whether a is in the range of [b, c].
115 */
116 #define time_in_range(a,b,c) \
117 (time_after_eq(a,b) && \
118 time_before_eq(a,c))
119
120 /*
121 * Calculate whether a is in the range of [b, c).
122 */
123 #define time_in_range_open(a,b,c) \
124 (time_after_eq(a,b) && \
125 time_before(a,c))
126
127 /* Same as above, but does so with platform independent 64bit types.
128 * These must be used when utilizing jiffies_64 (i.e. return value of
129 * get_jiffies_64() */
130 #define time_after64(a,b) \
131 (typecheck(__u64, a) && \
132 typecheck(__u64, b) && \
133 ((__s64)((b) - (a)) < 0))
134 #define time_before64(a,b) time_after64(b,a)
135
136 #define time_after_eq64(a,b) \
137 (typecheck(__u64, a) && \
138 typecheck(__u64, b) && \
139 ((__s64)((a) - (b)) >= 0))
140 #define time_before_eq64(a,b) time_after_eq64(b,a)
141
142 #define time_in_range64(a, b, c) \
143 (time_after_eq64(a, b) && \
144 time_before_eq64(a, c))
145
146 /*
147 * These four macros compare jiffies and 'a' for convenience.
148 */
149
150 /* time_is_before_jiffies(a) return true if a is before jiffies */
151 #define time_is_before_jiffies(a) time_after(jiffies, a)
152 #define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a)
153
154 /* time_is_after_jiffies(a) return true if a is after jiffies */
155 #define time_is_after_jiffies(a) time_before(jiffies, a)
156 #define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a)
157
158 /* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
159 #define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
160 #define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a)
161
162 /* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
163 #define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
164 #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)
165
166 /*
167 * Have the 32 bit jiffies value wrap 5 minutes after boot
168 * so jiffies wrap bugs show up earlier.
169 */
170 #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
171
172 /*
173 * Change timeval to jiffies, trying to avoid the
174 * most obvious overflows..
175 *
176 * And some not so obvious.
177 *
178 * Note that we don't want to return LONG_MAX, because
179 * for various timeout reasons we often end up having
180 * to wait "jiffies+1" in order to guarantee that we wait
181 * at _least_ "jiffies" - so "jiffies+1" had better still
182 * be positive.
183 */
184 #define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)
185
186 extern unsigned long preset_lpj;
187
188 /*
189 * We want to do realistic conversions of time so we need to use the same
190 * values the update wall clock code uses as the jiffies size. This value
191 * is: TICK_NSEC (which is defined in timex.h). This
192 * is a constant and is in nanoseconds. We will use scaled math
193 * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and
194 * NSEC_JIFFIE_SC. Note that these defines contain nothing but
195 * constants and so are computed at compile time. SHIFT_HZ (computed in
196 * timex.h) adjusts the scaling for different HZ values.
197
198 * Scaled math??? What is that?
199 *
200 * Scaled math is a way to do integer math on values that would,
201 * otherwise, either overflow, underflow, or cause undesired div
202 * instructions to appear in the execution path. In short, we "scale"
203 * up the operands so they take more bits (more precision, less
204 * underflow), do the desired operation and then "scale" the result back
205 * by the same amount. If we do the scaling by shifting we avoid the
206 * costly mpy and the dastardly div instructions.
207
208 * Suppose, for example, we want to convert from seconds to jiffies
209 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The
210 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We
211 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we
212 * might calculate at compile time, however, the result will only have
213 * about 3-4 bits of precision (less for smaller values of HZ).
214 *
215 * So, we scale as follows:
216 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);
217 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;
218 * Then we make SCALE a power of two so:
219 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;
220 * Now we define:
221 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))
222 * jiff = (sec * SEC_CONV) >> SCALE;
223 *
224 * Often the math we use will expand beyond 32-bits so we tell C how to
225 * do this and pass the 64-bit result of the mpy through the ">> SCALE"
226 * which should take the result back to 32-bits. We want this expansion
227 * to capture as much precision as possible. At the same time we don't
228 * want to overflow so we pick the SCALE to avoid this. In this file,
229 * that means using a different scale for each range of HZ values (as
230 * defined in timex.h).
231 *
232 * For those who want to know, gcc will give a 64-bit result from a "*"
233 * operator if the result is a long long AND at least one of the
234 * operands is cast to long long (usually just prior to the "*" so as
235 * not to confuse it into thinking it really has a 64-bit operand,
236 * which, buy the way, it can do, but it takes more code and at least 2
237 * mpys).
238
239 * We also need to be aware that one second in nanoseconds is only a
240 * couple of bits away from overflowing a 32-bit word, so we MUST use
241 * 64-bits to get the full range time in nanoseconds.
242
243 */
244
245 /*
246 * Here are the scales we will use. One for seconds, nanoseconds and
247 * microseconds.
248 *
249 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and
250 * check if the sign bit is set. If not, we bump the shift count by 1.
251 * (Gets an extra bit of precision where we can use it.)
252 * We know it is set for HZ = 1024 and HZ = 100 not for 1000.
253 * Haven't tested others.
254
255 * Limits of cpp (for #if expressions) only long (no long long), but
256 * then we only need the most signicant bit.
257 */
258
259 #define SEC_JIFFIE_SC (31 - SHIFT_HZ)
260 #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
261 #undef SEC_JIFFIE_SC
262 #define SEC_JIFFIE_SC (32 - SHIFT_HZ)
263 #endif
264 #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)
265 #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\
266 TICK_NSEC -1) / (u64)TICK_NSEC))
267
268 #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\
269 TICK_NSEC -1) / (u64)TICK_NSEC))
270 /*
271 * The maximum jiffie value is (MAX_INT >> 1). Here we translate that
272 * into seconds. The 64-bit case will overflow if we are not careful,
273 * so use the messy SH_DIV macro to do it. Still all constants.
274 */
275 #if BITS_PER_LONG < 64
276 # define MAX_SEC_IN_JIFFIES \
277 (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
278 #else /* take care of overflow on 64 bits machines */
279 # define MAX_SEC_IN_JIFFIES \
280 (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)
281
282 #endif
283
284 /*
285 * Convert various time units to each other:
286 */
287 extern unsigned int jiffies_to_msecs(const unsigned long j);
288 extern unsigned int jiffies_to_usecs(const unsigned long j);
289
jiffies_to_nsecs(const unsigned long j)290 static inline u64 jiffies_to_nsecs(const unsigned long j)
291 {
292 return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
293 }
294
295 extern unsigned long __msecs_to_jiffies(const unsigned int m);
296 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
297 /*
298 * HZ is equal to or smaller than 1000, and 1000 is a nice round
299 * multiple of HZ, divide with the factor between them, but round
300 * upwards:
301 */
_msecs_to_jiffies(const unsigned int m)302 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
303 {
304 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
305 }
306 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
307 /*
308 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 -
309 * simply multiply with the factor between them.
310 *
311 * But first make sure the multiplication result cannot overflow:
312 */
_msecs_to_jiffies(const unsigned int m)313 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
314 {
315 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
316 return MAX_JIFFY_OFFSET;
317 return m * (HZ / MSEC_PER_SEC);
318 }
319 #else
320 /*
321 * Generic case - multiply, round and divide. But first check that if
322 * we are doing a net multiplication, that we wouldn't overflow:
323 */
_msecs_to_jiffies(const unsigned int m)324 static inline unsigned long _msecs_to_jiffies(const unsigned int m)
325 {
326 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
327 return MAX_JIFFY_OFFSET;
328
329 return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32;
330 }
331 #endif
332 /**
333 * msecs_to_jiffies: - convert milliseconds to jiffies
334 * @m: time in milliseconds
335 *
336 * conversion is done as follows:
337 *
338 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
339 *
340 * - 'too large' values [that would result in larger than
341 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
342 *
343 * - all other values are converted to jiffies by either multiplying
344 * the input value by a factor or dividing it with a factor and
345 * handling any 32-bit overflows.
346 * for the details see __msecs_to_jiffies()
347 *
348 * msecs_to_jiffies() checks for the passed in value being a constant
349 * via __builtin_constant_p() allowing gcc to eliminate most of the
350 * code, __msecs_to_jiffies() is called if the value passed does not
351 * allow constant folding and the actual conversion must be done at
352 * runtime.
353 * the HZ range specific helpers _msecs_to_jiffies() are called both
354 * directly here and from __msecs_to_jiffies() in the case where
355 * constant folding is not possible.
356 */
msecs_to_jiffies(const unsigned int m)357 static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
358 {
359 if (__builtin_constant_p(m)) {
360 if ((int)m < 0)
361 return MAX_JIFFY_OFFSET;
362 return _msecs_to_jiffies(m);
363 } else {
364 return __msecs_to_jiffies(m);
365 }
366 }
367
368 extern unsigned long __usecs_to_jiffies(const unsigned int u);
369 #if !(USEC_PER_SEC % HZ)
_usecs_to_jiffies(const unsigned int u)370 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
371 {
372 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
373 }
374 #else
_usecs_to_jiffies(const unsigned int u)375 static inline unsigned long _usecs_to_jiffies(const unsigned int u)
376 {
377 return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
378 >> USEC_TO_HZ_SHR32;
379 }
380 #endif
381
382 /**
383 * usecs_to_jiffies: - convert microseconds to jiffies
384 * @u: time in microseconds
385 *
386 * conversion is done as follows:
387 *
388 * - 'too large' values [that would result in larger than
389 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
390 *
391 * - all other values are converted to jiffies by either multiplying
392 * the input value by a factor or dividing it with a factor and
393 * handling any 32-bit overflows as for msecs_to_jiffies.
394 *
395 * usecs_to_jiffies() checks for the passed in value being a constant
396 * via __builtin_constant_p() allowing gcc to eliminate most of the
397 * code, __usecs_to_jiffies() is called if the value passed does not
398 * allow constant folding and the actual conversion must be done at
399 * runtime.
400 * the HZ range specific helpers _usecs_to_jiffies() are called both
401 * directly here and from __msecs_to_jiffies() in the case where
402 * constant folding is not possible.
403 */
usecs_to_jiffies(const unsigned int u)404 static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
405 {
406 if (__builtin_constant_p(u)) {
407 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
408 return MAX_JIFFY_OFFSET;
409 return _usecs_to_jiffies(u);
410 } else {
411 return __usecs_to_jiffies(u);
412 }
413 }
414
415 extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
416 extern void jiffies_to_timespec64(const unsigned long jiffies,
417 struct timespec64 *value);
timespec_to_jiffies(const struct timespec * value)418 static inline unsigned long timespec_to_jiffies(const struct timespec *value)
419 {
420 struct timespec64 ts = timespec_to_timespec64(*value);
421
422 return timespec64_to_jiffies(&ts);
423 }
424
jiffies_to_timespec(const unsigned long jiffies,struct timespec * value)425 static inline void jiffies_to_timespec(const unsigned long jiffies,
426 struct timespec *value)
427 {
428 struct timespec64 ts;
429
430 jiffies_to_timespec64(jiffies, &ts);
431 *value = timespec64_to_timespec(ts);
432 }
433
434 extern unsigned long timeval_to_jiffies(const struct timeval *value);
435 extern void jiffies_to_timeval(const unsigned long jiffies,
436 struct timeval *value);
437
438 extern clock_t jiffies_to_clock_t(unsigned long x);
jiffies_delta_to_clock_t(long delta)439 static inline clock_t jiffies_delta_to_clock_t(long delta)
440 {
441 return jiffies_to_clock_t(max(0L, delta));
442 }
443
444 extern unsigned long clock_t_to_jiffies(unsigned long x);
445 extern u64 jiffies_64_to_clock_t(u64 x);
446 extern u64 nsec_to_clock_t(u64 x);
447 extern u64 nsecs_to_jiffies64(u64 n);
448 extern unsigned long nsecs_to_jiffies(u64 n);
449
450 #define TIMESTAMP_SIZE 30
451
452 #endif
453