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 62extern 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 on 32-bit systems - 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 * jiffies and jiffies_64 are at the same address for little-endian systems 80 * and for 64-bit big-endian systems. 81 * On 32-bit big-endian systems, jiffies is the lower 32 bits of jiffies_64 82 * (i.e., at address @jiffies_64 + 4). 83 * See arch/ARCH/kernel/vmlinux.lds.S 84 */ 85extern u64 __cacheline_aligned_in_smp jiffies_64; 86extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; 87 88#if (BITS_PER_LONG < 64) 89u64 get_jiffies_64(void); 90#else 91/** 92 * get_jiffies_64 - read the 64-bit non-atomic jiffies_64 value 93 * 94 * When BITS_PER_LONG < 64, this uses sequence number sampling using 95 * jiffies_lock to protect the 64-bit read. 96 * 97 * Return: current 64-bit jiffies value 98 */ 99static inline u64 get_jiffies_64(void) 100{ 101 return (u64)jiffies; 102} 103#endif 104 105/** 106 * DOC: General information about time_* inlines 107 * 108 * These inlines deal with timer wrapping correctly. You are strongly encouraged 109 * to use them: 110 * 111 * #. Because people otherwise forget 112 * #. Because if the timer wrap changes in future you won't have to alter your 113 * driver code. 114 */ 115 116/** 117 * time_after - returns true if the time a is after time b. 118 * @a: first comparable as unsigned long 119 * @b: second comparable as unsigned long 120 * 121 * Do this with "<0" and ">=0" to only test the sign of the result. A 122 * good compiler would generate better code (and a really good compiler 123 * wouldn't care). Gcc is currently neither. 124 * 125 * Return: %true is time a is after time b, otherwise %false. 126 */ 127#define time_after(a,b) \ 128 (typecheck(unsigned long, a) && \ 129 typecheck(unsigned long, b) && \ 130 ((long)((b) - (a)) < 0)) 131/** 132 * time_before - returns true if the time a is before time b. 133 * @a: first comparable as unsigned long 134 * @b: second comparable as unsigned long 135 * 136 * Return: %true is time a is before time b, otherwise %false. 137 */ 138#define time_before(a,b) time_after(b,a) 139 140/** 141 * time_after_eq - returns true if the time a is after or the same as time b. 142 * @a: first comparable as unsigned long 143 * @b: second comparable as unsigned long 144 * 145 * Return: %true is time a is after or the same as time b, otherwise %false. 146 */ 147#define time_after_eq(a,b) \ 148 (typecheck(unsigned long, a) && \ 149 typecheck(unsigned long, b) && \ 150 ((long)((a) - (b)) >= 0)) 151/** 152 * time_before_eq - returns true if the time a is before or the same as time b. 153 * @a: first comparable as unsigned long 154 * @b: second comparable as unsigned long 155 * 156 * Return: %true is time a is before or the same as time b, otherwise %false. 157 */ 158#define time_before_eq(a,b) time_after_eq(b,a) 159 160/** 161 * time_in_range - Calculate whether a is in the range of [b, c]. 162 * @a: time to test 163 * @b: beginning of the range 164 * @c: end of the range 165 * 166 * Return: %true is time a is in the range [b, c], otherwise %false. 167 */ 168#define time_in_range(a,b,c) \ 169 (time_after_eq(a,b) && \ 170 time_before_eq(a,c)) 171 172/** 173 * time_in_range_open - Calculate whether a is in the range of [b, c). 174 * @a: time to test 175 * @b: beginning of the range 176 * @c: end of the range 177 * 178 * Return: %true is time a is in the range [b, c), otherwise %false. 179 */ 180#define time_in_range_open(a,b,c) \ 181 (time_after_eq(a,b) && \ 182 time_before(a,c)) 183 184/* Same as above, but does so with platform independent 64bit types. 185 * These must be used when utilizing jiffies_64 (i.e. return value of 186 * get_jiffies_64()). */ 187 188/** 189 * time_after64 - returns true if the time a is after time b. 190 * @a: first comparable as __u64 191 * @b: second comparable as __u64 192 * 193 * This must be used when utilizing jiffies_64 (i.e. return value of 194 * get_jiffies_64()). 195 * 196 * Return: %true is time a is after time b, otherwise %false. 197 */ 198#define time_after64(a,b) \ 199 (typecheck(__u64, a) && \ 200 typecheck(__u64, b) && \ 201 ((__s64)((b) - (a)) < 0)) 202/** 203 * time_before64 - returns true if the time a is before time b. 204 * @a: first comparable as __u64 205 * @b: second comparable as __u64 206 * 207 * This must be used when utilizing jiffies_64 (i.e. return value of 208 * get_jiffies_64()). 209 * 210 * Return: %true is time a is before time b, otherwise %false. 211 */ 212#define time_before64(a,b) time_after64(b,a) 213 214/** 215 * time_after_eq64 - returns true if the time a is after or the same as time b. 216 * @a: first comparable as __u64 217 * @b: second comparable as __u64 218 * 219 * This must be used when utilizing jiffies_64 (i.e. return value of 220 * get_jiffies_64()). 221 * 222 * Return: %true is time a is after or the same as time b, otherwise %false. 223 */ 224#define time_after_eq64(a,b) \ 225 (typecheck(__u64, a) && \ 226 typecheck(__u64, b) && \ 227 ((__s64)((a) - (b)) >= 0)) 228/** 229 * time_before_eq64 - returns true if the time a is before or the same as time b. 230 * @a: first comparable as __u64 231 * @b: second comparable as __u64 232 * 233 * This must be used when utilizing jiffies_64 (i.e. return value of 234 * get_jiffies_64()). 235 * 236 * Return: %true is time a is before or the same as time b, otherwise %false. 237 */ 238#define time_before_eq64(a,b) time_after_eq64(b,a) 239 240/** 241 * time_in_range64 - Calculate whether a is in the range of [b, c]. 242 * @a: time to test 243 * @b: beginning of the range 244 * @c: end of the range 245 * 246 * Return: %true is time a is in the range [b, c], otherwise %false. 247 */ 248#define time_in_range64(a, b, c) \ 249 (time_after_eq64(a, b) && \ 250 time_before_eq64(a, c)) 251 252/* 253 * These eight macros compare jiffies[_64] and 'a' for convenience. 254 */ 255 256/** 257 * time_is_before_jiffies - return true if a is before jiffies 258 * @a: time (unsigned long) to compare to jiffies 259 * 260 * Return: %true is time a is before jiffies, otherwise %false. 261 */ 262#define time_is_before_jiffies(a) time_after(jiffies, a) 263/** 264 * time_is_before_jiffies64 - return true if a is before jiffies_64 265 * @a: time (__u64) to compare to jiffies_64 266 * 267 * Return: %true is time a is before jiffies_64, otherwise %false. 268 */ 269#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a) 270 271/** 272 * time_is_after_jiffies - return true if a is after jiffies 273 * @a: time (unsigned long) to compare to jiffies 274 * 275 * Return: %true is time a is after jiffies, otherwise %false. 276 */ 277#define time_is_after_jiffies(a) time_before(jiffies, a) 278/** 279 * time_is_after_jiffies64 - return true if a is after jiffies_64 280 * @a: time (__u64) to compare to jiffies_64 281 * 282 * Return: %true is time a is after jiffies_64, otherwise %false. 283 */ 284#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a) 285 286/** 287 * time_is_before_eq_jiffies - return true if a is before or equal to jiffies 288 * @a: time (unsigned long) to compare to jiffies 289 * 290 * Return: %true is time a is before or the same as jiffies, otherwise %false. 291 */ 292#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) 293/** 294 * time_is_before_eq_jiffies64 - return true if a is before or equal to jiffies_64 295 * @a: time (__u64) to compare to jiffies_64 296 * 297 * Return: %true is time a is before or the same jiffies_64, otherwise %false. 298 */ 299#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a) 300 301/** 302 * time_is_after_eq_jiffies - return true if a is after or equal to jiffies 303 * @a: time (unsigned long) to compare to jiffies 304 * 305 * Return: %true is time a is after or the same as jiffies, otherwise %false. 306 */ 307#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) 308/** 309 * time_is_after_eq_jiffies64 - return true if a is after or equal to jiffies_64 310 * @a: time (__u64) to compare to jiffies_64 311 * 312 * Return: %true is time a is after or the same as jiffies_64, otherwise %false. 313 */ 314#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a) 315 316/* 317 * Have the 32-bit jiffies value wrap 5 minutes after boot 318 * so jiffies wrap bugs show up earlier. 319 */ 320#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) 321 322/* 323 * Change timeval to jiffies, trying to avoid the 324 * most obvious overflows.. 325 * 326 * And some not so obvious. 327 * 328 * Note that we don't want to return LONG_MAX, because 329 * for various timeout reasons we often end up having 330 * to wait "jiffies+1" in order to guarantee that we wait 331 * at _least_ "jiffies" - so "jiffies+1" had better still 332 * be positive. 333 */ 334#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) 335 336extern unsigned long preset_lpj; 337 338/* 339 * We want to do realistic conversions of time so we need to use the same 340 * values the update wall clock code uses as the jiffies size. This value 341 * is: TICK_NSEC (which is defined in timex.h). This 342 * is a constant and is in nanoseconds. We will use scaled math 343 * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and 344 * NSEC_JIFFIE_SC. Note that these defines contain nothing but 345 * constants and so are computed at compile time. SHIFT_HZ (computed in 346 * timex.h) adjusts the scaling for different HZ values. 347 348 * Scaled math??? What is that? 349 * 350 * Scaled math is a way to do integer math on values that would, 351 * otherwise, either overflow, underflow, or cause undesired div 352 * instructions to appear in the execution path. In short, we "scale" 353 * up the operands so they take more bits (more precision, less 354 * underflow), do the desired operation and then "scale" the result back 355 * by the same amount. If we do the scaling by shifting we avoid the 356 * costly mpy and the dastardly div instructions. 357 358 * Suppose, for example, we want to convert from seconds to jiffies 359 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The 360 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We 361 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we 362 * might calculate at compile time, however, the result will only have 363 * about 3-4 bits of precision (less for smaller values of HZ). 364 * 365 * So, we scale as follows: 366 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); 367 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; 368 * Then we make SCALE a power of two so: 369 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; 370 * Now we define: 371 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) 372 * jiff = (sec * SEC_CONV) >> SCALE; 373 * 374 * Often the math we use will expand beyond 32-bits so we tell C how to 375 * do this and pass the 64-bit result of the mpy through the ">> SCALE" 376 * which should take the result back to 32-bits. We want this expansion 377 * to capture as much precision as possible. At the same time we don't 378 * want to overflow so we pick the SCALE to avoid this. In this file, 379 * that means using a different scale for each range of HZ values (as 380 * defined in timex.h). 381 * 382 * For those who want to know, gcc will give a 64-bit result from a "*" 383 * operator if the result is a long long AND at least one of the 384 * operands is cast to long long (usually just prior to the "*" so as 385 * not to confuse it into thinking it really has a 64-bit operand, 386 * which, buy the way, it can do, but it takes more code and at least 2 387 * mpys). 388 389 * We also need to be aware that one second in nanoseconds is only a 390 * couple of bits away from overflowing a 32-bit word, so we MUST use 391 * 64-bits to get the full range time in nanoseconds. 392 393 */ 394 395/* 396 * Here are the scales we will use. One for seconds, nanoseconds and 397 * microseconds. 398 * 399 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and 400 * check if the sign bit is set. If not, we bump the shift count by 1. 401 * (Gets an extra bit of precision where we can use it.) 402 * We know it is set for HZ = 1024 and HZ = 100 not for 1000. 403 * Haven't tested others. 404 405 * Limits of cpp (for #if expressions) only long (no long long), but 406 * then we only need the most signicant bit. 407 */ 408 409#define SEC_JIFFIE_SC (31 - SHIFT_HZ) 410#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) 411#undef SEC_JIFFIE_SC 412#define SEC_JIFFIE_SC (32 - SHIFT_HZ) 413#endif 414#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) 415#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ 416 TICK_NSEC -1) / (u64)TICK_NSEC)) 417 418#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ 419 TICK_NSEC -1) / (u64)TICK_NSEC)) 420/* 421 * The maximum jiffie value is (MAX_INT >> 1). Here we translate that 422 * into seconds. The 64-bit case will overflow if we are not careful, 423 * so use the messy SH_DIV macro to do it. Still all constants. 424 */ 425#if BITS_PER_LONG < 64 426# define MAX_SEC_IN_JIFFIES \ 427 (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) 428#else /* take care of overflow on 64-bit machines */ 429# define MAX_SEC_IN_JIFFIES \ 430 (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) 431 432#endif 433 434/* 435 * Convert various time units to each other: 436 */ 437extern unsigned int jiffies_to_msecs(const unsigned long j); 438extern unsigned int jiffies_to_usecs(const unsigned long j); 439 440/** 441 * jiffies_to_nsecs - Convert jiffies to nanoseconds 442 * @j: jiffies value 443 * 444 * Return: nanoseconds value 445 */ 446static inline u64 jiffies_to_nsecs(const unsigned long j) 447{ 448 return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; 449} 450 451extern u64 jiffies64_to_nsecs(u64 j); 452extern u64 jiffies64_to_msecs(u64 j); 453 454extern unsigned long __msecs_to_jiffies(const unsigned int m); 455#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) 456/* 457 * HZ is equal to or smaller than 1000, and 1000 is a nice round 458 * multiple of HZ, divide with the factor between them, but round 459 * upwards: 460 */ 461static inline unsigned long _msecs_to_jiffies(const unsigned int m) 462{ 463 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); 464} 465#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) 466/* 467 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 - 468 * simply multiply with the factor between them. 469 * 470 * But first make sure the multiplication result cannot overflow: 471 */ 472static inline unsigned long _msecs_to_jiffies(const unsigned int m) 473{ 474 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) 475 return MAX_JIFFY_OFFSET; 476 return m * (HZ / MSEC_PER_SEC); 477} 478#else 479/* 480 * Generic case - multiply, round and divide. But first check that if 481 * we are doing a net multiplication, that we wouldn't overflow: 482 */ 483static inline unsigned long _msecs_to_jiffies(const unsigned int m) 484{ 485 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) 486 return MAX_JIFFY_OFFSET; 487 488 return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32; 489} 490#endif 491/** 492 * msecs_to_jiffies: - convert milliseconds to jiffies 493 * @m: time in milliseconds 494 * 495 * conversion is done as follows: 496 * 497 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) 498 * 499 * - 'too large' values [that would result in larger than 500 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. 501 * 502 * - all other values are converted to jiffies by either multiplying 503 * the input value by a factor or dividing it with a factor and 504 * handling any 32-bit overflows. 505 * for the details see __msecs_to_jiffies() 506 * 507 * msecs_to_jiffies() checks for the passed in value being a constant 508 * via __builtin_constant_p() allowing gcc to eliminate most of the 509 * code. __msecs_to_jiffies() is called if the value passed does not 510 * allow constant folding and the actual conversion must be done at 511 * runtime. 512 * The HZ range specific helpers _msecs_to_jiffies() are called both 513 * directly here and from __msecs_to_jiffies() in the case where 514 * constant folding is not possible. 515 * 516 * Return: jiffies value 517 */ 518static __always_inline unsigned long msecs_to_jiffies(const unsigned int m) 519{ 520 if (__builtin_constant_p(m)) { 521 if ((int)m < 0) 522 return MAX_JIFFY_OFFSET; 523 return _msecs_to_jiffies(m); 524 } else { 525 return __msecs_to_jiffies(m); 526 } 527} 528 529extern unsigned long __usecs_to_jiffies(const unsigned int u); 530#if !(USEC_PER_SEC % HZ) 531static inline unsigned long _usecs_to_jiffies(const unsigned int u) 532{ 533 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); 534} 535#else 536static inline unsigned long _usecs_to_jiffies(const unsigned int u) 537{ 538 return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) 539 >> USEC_TO_HZ_SHR32; 540} 541#endif 542 543/** 544 * usecs_to_jiffies: - convert microseconds to jiffies 545 * @u: time in microseconds 546 * 547 * conversion is done as follows: 548 * 549 * - 'too large' values [that would result in larger than 550 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. 551 * 552 * - all other values are converted to jiffies by either multiplying 553 * the input value by a factor or dividing it with a factor and 554 * handling any 32-bit overflows as for msecs_to_jiffies. 555 * 556 * usecs_to_jiffies() checks for the passed in value being a constant 557 * via __builtin_constant_p() allowing gcc to eliminate most of the 558 * code. __usecs_to_jiffies() is called if the value passed does not 559 * allow constant folding and the actual conversion must be done at 560 * runtime. 561 * The HZ range specific helpers _usecs_to_jiffies() are called both 562 * directly here and from __msecs_to_jiffies() in the case where 563 * constant folding is not possible. 564 * 565 * Return: jiffies value 566 */ 567static __always_inline unsigned long usecs_to_jiffies(const unsigned int u) 568{ 569 if (__builtin_constant_p(u)) { 570 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) 571 return MAX_JIFFY_OFFSET; 572 return _usecs_to_jiffies(u); 573 } else { 574 return __usecs_to_jiffies(u); 575 } 576} 577 578extern unsigned long timespec64_to_jiffies(const struct timespec64 *value); 579extern void jiffies_to_timespec64(const unsigned long jiffies, 580 struct timespec64 *value); 581extern clock_t jiffies_to_clock_t(unsigned long x); 582 583static inline clock_t jiffies_delta_to_clock_t(long delta) 584{ 585 return jiffies_to_clock_t(max(0L, delta)); 586} 587 588static inline unsigned int jiffies_delta_to_msecs(long delta) 589{ 590 return jiffies_to_msecs(max(0L, delta)); 591} 592 593extern unsigned long clock_t_to_jiffies(unsigned long x); 594extern u64 jiffies_64_to_clock_t(u64 x); 595extern u64 nsec_to_clock_t(u64 x); 596extern u64 nsecs_to_jiffies64(u64 n); 597extern unsigned long nsecs_to_jiffies(u64 n); 598 599#define TIMESTAMP_SIZE 30 600 601#endif 602