1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_JIFFIES_H |
3 | #define _LINUX_JIFFIES_H |
4 | |
5 | #include <linux/cache.h> |
6 | #include <linux/limits.h> |
7 | #include <linux/math64.h> |
8 | #include <linux/minmax.h> |
9 | #include <linux/types.h> |
10 | #include <linux/time.h> |
11 | #include <linux/timex.h> |
12 | #include <vdso/jiffies.h> |
13 | #include <asm/param.h> /* for HZ */ |
14 | #include <generated/timeconst.h> |
15 | |
16 | /* |
17 | * The following defines establish the engineering parameters of the PLL |
18 | * model. The HZ variable establishes the timer interrupt frequency, 100 Hz |
19 | * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the |
20 | * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the |
21 | * nearest power of two in order to avoid hardware multiply operations. |
22 | */ |
23 | #if HZ >= 12 && HZ < 24 |
24 | # define SHIFT_HZ 4 |
25 | #elif HZ >= 24 && HZ < 48 |
26 | # define SHIFT_HZ 5 |
27 | #elif HZ >= 48 && HZ < 96 |
28 | # define SHIFT_HZ 6 |
29 | #elif HZ >= 96 && HZ < 192 |
30 | # define SHIFT_HZ 7 |
31 | #elif HZ >= 192 && HZ < 384 |
32 | # define SHIFT_HZ 8 |
33 | #elif HZ >= 384 && HZ < 768 |
34 | # define SHIFT_HZ 9 |
35 | #elif HZ >= 768 && HZ < 1536 |
36 | # define SHIFT_HZ 10 |
37 | #elif HZ >= 1536 && HZ < 3072 |
38 | # define SHIFT_HZ 11 |
39 | #elif HZ >= 3072 && HZ < 6144 |
40 | # define SHIFT_HZ 12 |
41 | #elif HZ >= 6144 && HZ < 12288 |
42 | # define SHIFT_HZ 13 |
43 | #else |
44 | # error Invalid value of HZ. |
45 | #endif |
46 | |
47 | /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can |
48 | * improve accuracy by shifting LSH bits, hence calculating: |
49 | * (NOM << LSH) / DEN |
50 | * This however means trouble for large NOM, because (NOM << LSH) may no |
51 | * longer fit in 32 bits. The following way of calculating this gives us |
52 | * some slack, under the following conditions: |
53 | * - (NOM / DEN) fits in (32 - LSH) bits. |
54 | * - (NOM % DEN) fits in (32 - LSH) bits. |
55 | */ |
56 | #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ |
57 | + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) |
58 | |
59 | /* LATCH is used in the interval timer and ftape setup. */ |
60 | #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ |
61 | |
62 | extern int register_refined_jiffies(long clock_tick_rate); |
63 | |
64 | /* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */ |
65 | #define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ) |
66 | |
67 | /* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ |
68 | #define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) |
69 | |
70 | #ifndef __jiffy_arch_data |
71 | #define __jiffy_arch_data |
72 | #endif |
73 | |
74 | /* |
75 | * The 64-bit value is not atomic - you MUST NOT read it |
76 | * without sampling the sequence number in jiffies_lock. |
77 | * get_jiffies_64() will do this for you as appropriate. |
78 | */ |
79 | extern u64 __cacheline_aligned_in_smp jiffies_64; |
80 | extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; |
81 | |
82 | #if (BITS_PER_LONG < 64) |
83 | u64 get_jiffies_64(void); |
84 | #else |
85 | static inline u64 get_jiffies_64(void) |
86 | { |
87 | return (u64)jiffies; |
88 | } |
89 | #endif |
90 | |
91 | /* |
92 | * These inlines deal with timer wrapping correctly. You are |
93 | * strongly encouraged to use them |
94 | * 1. Because people otherwise forget |
95 | * 2. Because if the timer wrap changes in future you won't have to |
96 | * alter your driver code. |
97 | * |
98 | * time_after(a,b) returns true if the time a is after time b. |
99 | * |
100 | * Do this with "<0" and ">=0" to only test the sign of the result. A |
101 | * good compiler would generate better code (and a really good compiler |
102 | * wouldn't care). Gcc is currently neither. |
103 | */ |
104 | #define time_after(a,b) \ |
105 | (typecheck(unsigned long, a) && \ |
106 | typecheck(unsigned long, b) && \ |
107 | ((long)((b) - (a)) < 0)) |
108 | #define time_before(a,b) time_after(b,a) |
109 | |
110 | #define time_after_eq(a,b) \ |
111 | (typecheck(unsigned long, a) && \ |
112 | typecheck(unsigned long, b) && \ |
113 | ((long)((a) - (b)) >= 0)) |
114 | #define time_before_eq(a,b) time_after_eq(b,a) |
115 | |
116 | /* |
117 | * Calculate whether a is in the range of [b, c]. |
118 | */ |
119 | #define time_in_range(a,b,c) \ |
120 | (time_after_eq(a,b) && \ |
121 | time_before_eq(a,c)) |
122 | |
123 | /* |
124 | * Calculate whether a is in the range of [b, c). |
125 | */ |
126 | #define time_in_range_open(a,b,c) \ |
127 | (time_after_eq(a,b) && \ |
128 | time_before(a,c)) |
129 | |
130 | /* Same as above, but does so with platform independent 64bit types. |
131 | * These must be used when utilizing jiffies_64 (i.e. return value of |
132 | * get_jiffies_64() */ |
133 | #define time_after64(a,b) \ |
134 | (typecheck(__u64, a) && \ |
135 | typecheck(__u64, b) && \ |
136 | ((__s64)((b) - (a)) < 0)) |
137 | #define time_before64(a,b) time_after64(b,a) |
138 | |
139 | #define time_after_eq64(a,b) \ |
140 | (typecheck(__u64, a) && \ |
141 | typecheck(__u64, b) && \ |
142 | ((__s64)((a) - (b)) >= 0)) |
143 | #define time_before_eq64(a,b) time_after_eq64(b,a) |
144 | |
145 | #define time_in_range64(a, b, c) \ |
146 | (time_after_eq64(a, b) && \ |
147 | time_before_eq64(a, c)) |
148 | |
149 | /* |
150 | * These four macros compare jiffies and 'a' for convenience. |
151 | */ |
152 | |
153 | /* time_is_before_jiffies(a) return true if a is before jiffies */ |
154 | #define time_is_before_jiffies(a) time_after(jiffies, a) |
155 | #define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a) |
156 | |
157 | /* time_is_after_jiffies(a) return true if a is after jiffies */ |
158 | #define time_is_after_jiffies(a) time_before(jiffies, a) |
159 | #define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a) |
160 | |
161 | /* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ |
162 | #define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) |
163 | #define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a) |
164 | |
165 | /* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ |
166 | #define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) |
167 | #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a) |
168 | |
169 | /* |
170 | * Have the 32 bit jiffies value wrap 5 minutes after boot |
171 | * so jiffies wrap bugs show up earlier. |
172 | */ |
173 | #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) |
174 | |
175 | /* |
176 | * Change timeval to jiffies, trying to avoid the |
177 | * most obvious overflows.. |
178 | * |
179 | * And some not so obvious. |
180 | * |
181 | * Note that we don't want to return LONG_MAX, because |
182 | * for various timeout reasons we often end up having |
183 | * to wait "jiffies+1" in order to guarantee that we wait |
184 | * at _least_ "jiffies" - so "jiffies+1" had better still |
185 | * be positive. |
186 | */ |
187 | #define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) |
188 | |
189 | extern unsigned long preset_lpj; |
190 | |
191 | /* |
192 | * We want to do realistic conversions of time so we need to use the same |
193 | * values the update wall clock code uses as the jiffies size. This value |
194 | * is: TICK_NSEC (which is defined in timex.h). This |
195 | * is a constant and is in nanoseconds. We will use scaled math |
196 | * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and |
197 | * NSEC_JIFFIE_SC. Note that these defines contain nothing but |
198 | * constants and so are computed at compile time. SHIFT_HZ (computed in |
199 | * timex.h) adjusts the scaling for different HZ values. |
200 | |
201 | * Scaled math??? What is that? |
202 | * |
203 | * Scaled math is a way to do integer math on values that would, |
204 | * otherwise, either overflow, underflow, or cause undesired div |
205 | * instructions to appear in the execution path. In short, we "scale" |
206 | * up the operands so they take more bits (more precision, less |
207 | * underflow), do the desired operation and then "scale" the result back |
208 | * by the same amount. If we do the scaling by shifting we avoid the |
209 | * costly mpy and the dastardly div instructions. |
210 | |
211 | * Suppose, for example, we want to convert from seconds to jiffies |
212 | * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The |
213 | * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We |
214 | * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we |
215 | * might calculate at compile time, however, the result will only have |
216 | * about 3-4 bits of precision (less for smaller values of HZ). |
217 | * |
218 | * So, we scale as follows: |
219 | * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); |
220 | * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; |
221 | * Then we make SCALE a power of two so: |
222 | * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; |
223 | * Now we define: |
224 | * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) |
225 | * jiff = (sec * SEC_CONV) >> SCALE; |
226 | * |
227 | * Often the math we use will expand beyond 32-bits so we tell C how to |
228 | * do this and pass the 64-bit result of the mpy through the ">> SCALE" |
229 | * which should take the result back to 32-bits. We want this expansion |
230 | * to capture as much precision as possible. At the same time we don't |
231 | * want to overflow so we pick the SCALE to avoid this. In this file, |
232 | * that means using a different scale for each range of HZ values (as |
233 | * defined in timex.h). |
234 | * |
235 | * For those who want to know, gcc will give a 64-bit result from a "*" |
236 | * operator if the result is a long long AND at least one of the |
237 | * operands is cast to long long (usually just prior to the "*" so as |
238 | * not to confuse it into thinking it really has a 64-bit operand, |
239 | * which, buy the way, it can do, but it takes more code and at least 2 |
240 | * mpys). |
241 | |
242 | * We also need to be aware that one second in nanoseconds is only a |
243 | * couple of bits away from overflowing a 32-bit word, so we MUST use |
244 | * 64-bits to get the full range time in nanoseconds. |
245 | |
246 | */ |
247 | |
248 | /* |
249 | * Here are the scales we will use. One for seconds, nanoseconds and |
250 | * microseconds. |
251 | * |
252 | * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and |
253 | * check if the sign bit is set. If not, we bump the shift count by 1. |
254 | * (Gets an extra bit of precision where we can use it.) |
255 | * We know it is set for HZ = 1024 and HZ = 100 not for 1000. |
256 | * Haven't tested others. |
257 | |
258 | * Limits of cpp (for #if expressions) only long (no long long), but |
259 | * then we only need the most signicant bit. |
260 | */ |
261 | |
262 | #define SEC_JIFFIE_SC (31 - SHIFT_HZ) |
263 | #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) |
264 | #undef SEC_JIFFIE_SC |
265 | #define SEC_JIFFIE_SC (32 - SHIFT_HZ) |
266 | #endif |
267 | #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) |
268 | #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ |
269 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
270 | |
271 | #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ |
272 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
273 | /* |
274 | * The maximum jiffie value is (MAX_INT >> 1). Here we translate that |
275 | * into seconds. The 64-bit case will overflow if we are not careful, |
276 | * so use the messy SH_DIV macro to do it. Still all constants. |
277 | */ |
278 | #if BITS_PER_LONG < 64 |
279 | # define MAX_SEC_IN_JIFFIES \ |
280 | (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) |
281 | #else /* take care of overflow on 64 bits machines */ |
282 | # define MAX_SEC_IN_JIFFIES \ |
283 | (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) |
284 | |
285 | #endif |
286 | |
287 | /* |
288 | * Convert various time units to each other: |
289 | */ |
290 | extern unsigned int jiffies_to_msecs(const unsigned long j); |
291 | extern unsigned int jiffies_to_usecs(const unsigned long j); |
292 | |
293 | static inline u64 jiffies_to_nsecs(const unsigned long j) |
294 | { |
295 | return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; |
296 | } |
297 | |
298 | extern u64 jiffies64_to_nsecs(u64 j); |
299 | extern u64 jiffies64_to_msecs(u64 j); |
300 | |
301 | extern unsigned long __msecs_to_jiffies(const unsigned int m); |
302 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
303 | /* |
304 | * HZ is equal to or smaller than 1000, and 1000 is a nice round |
305 | * multiple of HZ, divide with the factor between them, but round |
306 | * upwards: |
307 | */ |
308 | static inline unsigned long _msecs_to_jiffies(const unsigned int m) |
309 | { |
310 | return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); |
311 | } |
312 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) |
313 | /* |
314 | * HZ is larger than 1000, and HZ is a nice round multiple of 1000 - |
315 | * simply multiply with the factor between them. |
316 | * |
317 | * But first make sure the multiplication result cannot overflow: |
318 | */ |
319 | static inline unsigned long _msecs_to_jiffies(const unsigned int m) |
320 | { |
321 | if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) |
322 | return MAX_JIFFY_OFFSET; |
323 | return m * (HZ / MSEC_PER_SEC); |
324 | } |
325 | #else |
326 | /* |
327 | * Generic case - multiply, round and divide. But first check that if |
328 | * we are doing a net multiplication, that we wouldn't overflow: |
329 | */ |
330 | static inline unsigned long _msecs_to_jiffies(const unsigned int m) |
331 | { |
332 | if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) |
333 | return MAX_JIFFY_OFFSET; |
334 | |
335 | return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32; |
336 | } |
337 | #endif |
338 | /** |
339 | * msecs_to_jiffies: - convert milliseconds to jiffies |
340 | * @m: time in milliseconds |
341 | * |
342 | * conversion is done as follows: |
343 | * |
344 | * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) |
345 | * |
346 | * - 'too large' values [that would result in larger than |
347 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. |
348 | * |
349 | * - all other values are converted to jiffies by either multiplying |
350 | * the input value by a factor or dividing it with a factor and |
351 | * handling any 32-bit overflows. |
352 | * for the details see __msecs_to_jiffies() |
353 | * |
354 | * msecs_to_jiffies() checks for the passed in value being a constant |
355 | * via __builtin_constant_p() allowing gcc to eliminate most of the |
356 | * code, __msecs_to_jiffies() is called if the value passed does not |
357 | * allow constant folding and the actual conversion must be done at |
358 | * runtime. |
359 | * the HZ range specific helpers _msecs_to_jiffies() are called both |
360 | * directly here and from __msecs_to_jiffies() in the case where |
361 | * constant folding is not possible. |
362 | */ |
363 | static __always_inline unsigned long msecs_to_jiffies(const unsigned int m) |
364 | { |
365 | if (__builtin_constant_p(m)) { |
366 | if ((int)m < 0) |
367 | return MAX_JIFFY_OFFSET; |
368 | return _msecs_to_jiffies(m); |
369 | } else { |
370 | return __msecs_to_jiffies(m); |
371 | } |
372 | } |
373 | |
374 | extern unsigned long __usecs_to_jiffies(const unsigned int u); |
375 | #if !(USEC_PER_SEC % HZ) |
376 | static inline unsigned long _usecs_to_jiffies(const unsigned int u) |
377 | { |
378 | return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); |
379 | } |
380 | #else |
381 | static inline unsigned long _usecs_to_jiffies(const unsigned int u) |
382 | { |
383 | return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) |
384 | >> USEC_TO_HZ_SHR32; |
385 | } |
386 | #endif |
387 | |
388 | /** |
389 | * usecs_to_jiffies: - convert microseconds to jiffies |
390 | * @u: time in microseconds |
391 | * |
392 | * conversion is done as follows: |
393 | * |
394 | * - 'too large' values [that would result in larger than |
395 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. |
396 | * |
397 | * - all other values are converted to jiffies by either multiplying |
398 | * the input value by a factor or dividing it with a factor and |
399 | * handling any 32-bit overflows as for msecs_to_jiffies. |
400 | * |
401 | * usecs_to_jiffies() checks for the passed in value being a constant |
402 | * via __builtin_constant_p() allowing gcc to eliminate most of the |
403 | * code, __usecs_to_jiffies() is called if the value passed does not |
404 | * allow constant folding and the actual conversion must be done at |
405 | * runtime. |
406 | * the HZ range specific helpers _usecs_to_jiffies() are called both |
407 | * directly here and from __msecs_to_jiffies() in the case where |
408 | * constant folding is not possible. |
409 | */ |
410 | static __always_inline unsigned long usecs_to_jiffies(const unsigned int u) |
411 | { |
412 | if (__builtin_constant_p(u)) { |
413 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) |
414 | return MAX_JIFFY_OFFSET; |
415 | return _usecs_to_jiffies(u); |
416 | } else { |
417 | return __usecs_to_jiffies(u); |
418 | } |
419 | } |
420 | |
421 | extern unsigned long timespec64_to_jiffies(const struct timespec64 *value); |
422 | extern void jiffies_to_timespec64(const unsigned long jiffies, |
423 | struct timespec64 *value); |
424 | extern clock_t jiffies_to_clock_t(unsigned long x); |
425 | static inline clock_t jiffies_delta_to_clock_t(long delta) |
426 | { |
427 | return jiffies_to_clock_t(max(0L, delta)); |
428 | } |
429 | |
430 | static inline unsigned int jiffies_delta_to_msecs(long delta) |
431 | { |
432 | return jiffies_to_msecs(max(0L, delta)); |
433 | } |
434 | |
435 | extern unsigned long clock_t_to_jiffies(unsigned long x); |
436 | extern u64 jiffies_64_to_clock_t(u64 x); |
437 | extern u64 nsec_to_clock_t(u64 x); |
438 | extern u64 nsecs_to_jiffies64(u64 n); |
439 | extern unsigned long nsecs_to_jiffies(u64 n); |
440 | |
441 | #define TIMESTAMP_SIZE 30 |
442 | |
443 | #endif |
444 | |