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/math64.h> 7#include <linux/kernel.h> 8#include <linux/types.h> 9#include <linux/time.h> 10#include <linux/timex.h> 11#include <asm/param.h> /* for HZ */ 12#include <generated/timeconst.h> 13 14/* 15 * The following defines establish the engineering parameters of the PLL 16 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz 17 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the 18 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the 19 * nearest power of two in order to avoid hardware multiply operations. 20 */ 21#if HZ >= 12 && HZ < 24 22# define SHIFT_HZ 4 23#elif HZ >= 24 && HZ < 48 24# define SHIFT_HZ 5 25#elif HZ >= 48 && HZ < 96 26# define SHIFT_HZ 6 27#elif HZ >= 96 && HZ < 192 28# define SHIFT_HZ 7 29#elif HZ >= 192 && HZ < 384 30# define SHIFT_HZ 8 31#elif HZ >= 384 && HZ < 768 32# define SHIFT_HZ 9 33#elif HZ >= 768 && HZ < 1536 34# define SHIFT_HZ 10 35#elif HZ >= 1536 && HZ < 3072 36# define SHIFT_HZ 11 37#elif HZ >= 3072 && HZ < 6144 38# define SHIFT_HZ 12 39#elif HZ >= 6144 && HZ < 12288 40# define SHIFT_HZ 13 41#else 42# error Invalid value of HZ. 43#endif 44 45/* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can 46 * improve accuracy by shifting LSH bits, hence calculating: 47 * (NOM << LSH) / DEN 48 * This however means trouble for large NOM, because (NOM << LSH) may no 49 * longer fit in 32 bits. The following way of calculating this gives us 50 * some slack, under the following conditions: 51 * - (NOM / DEN) fits in (32 - LSH) bits. 52 * - (NOM % DEN) fits in (32 - LSH) bits. 53 */ 54#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ 55 + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) 56 57/* LATCH is used in the interval timer and ftape setup. */ 58#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ 59 60extern int register_refined_jiffies(long clock_tick_rate); 61 62/* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */ 63#define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ) 64 65/* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */ 66#define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ) 67 68/* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ 69#define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) 70 71#ifndef __jiffy_arch_data 72#define __jiffy_arch_data 73#endif 74 75/* 76 * The 64-bit value is not atomic - you MUST NOT read it 77 * without sampling the sequence number in jiffies_lock. 78 * get_jiffies_64() will do this for you as appropriate. 79 */ 80extern u64 __cacheline_aligned_in_smp jiffies_64; 81extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; 82 83#if (BITS_PER_LONG < 64) 84u64 get_jiffies_64(void); 85#else 86static inline u64 get_jiffies_64(void) 87{ 88 return (u64)jiffies; 89} 90#endif 91 92/* 93 * These inlines deal with timer wrapping correctly. You are 94 * strongly encouraged to use them 95 * 1. Because people otherwise forget 96 * 2. Because if the timer wrap changes in future you won't have to 97 * alter your driver code. 98 * 99 * time_after(a,b) returns true if the time a is after time b. 100 * 101 * Do this with "<0" and ">=0" to only test the sign of the result. A 102 * good compiler would generate better code (and a really good compiler 103 * wouldn't care). Gcc is currently neither. 104 */ 105#define time_after(a,b) \ 106 (typecheck(unsigned long, a) && \ 107 typecheck(unsigned long, b) && \ 108 ((long)((b) - (a)) < 0)) 109#define time_before(a,b) time_after(b,a) 110 111#define time_after_eq(a,b) \ 112 (typecheck(unsigned long, a) && \ 113 typecheck(unsigned long, b) && \ 114 ((long)((a) - (b)) >= 0)) 115#define time_before_eq(a,b) time_after_eq(b,a) 116 117/* 118 * Calculate whether a is in the range of [b, c]. 119 */ 120#define time_in_range(a,b,c) \ 121 (time_after_eq(a,b) && \ 122 time_before_eq(a,c)) 123 124/* 125 * Calculate whether a is in the range of [b, c). 126 */ 127#define time_in_range_open(a,b,c) \ 128 (time_after_eq(a,b) && \ 129 time_before(a,c)) 130 131/* Same as above, but does so with platform independent 64bit types. 132 * These must be used when utilizing jiffies_64 (i.e. return value of 133 * get_jiffies_64() */ 134#define time_after64(a,b) \ 135 (typecheck(__u64, a) && \ 136 typecheck(__u64, b) && \ 137 ((__s64)((b) - (a)) < 0)) 138#define time_before64(a,b) time_after64(b,a) 139 140#define time_after_eq64(a,b) \ 141 (typecheck(__u64, a) && \ 142 typecheck(__u64, b) && \ 143 ((__s64)((a) - (b)) >= 0)) 144#define time_before_eq64(a,b) time_after_eq64(b,a) 145 146#define time_in_range64(a, b, c) \ 147 (time_after_eq64(a, b) && \ 148 time_before_eq64(a, c)) 149 150/* 151 * These four macros compare jiffies and 'a' for convenience. 152 */ 153 154/* time_is_before_jiffies(a) return true if a is before jiffies */ 155#define time_is_before_jiffies(a) time_after(jiffies, a) 156#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a) 157 158/* time_is_after_jiffies(a) return true if a is after jiffies */ 159#define time_is_after_jiffies(a) time_before(jiffies, a) 160#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a) 161 162/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ 163#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) 164#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a) 165 166/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ 167#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) 168#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a) 169 170/* 171 * Have the 32 bit jiffies value wrap 5 minutes after boot 172 * so jiffies wrap bugs show up earlier. 173 */ 174#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) 175 176/* 177 * Change timeval to jiffies, trying to avoid the 178 * most obvious overflows.. 179 * 180 * And some not so obvious. 181 * 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 186 * be positive. 187 */ 188#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) 189 190extern unsigned long preset_lpj; 191 192/* 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. 201 202 * Scaled math??? What is that? 203 * 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. 211 212 * 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). 218 * 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; 224 * Now we define: 225 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) 226 * jiff = (sec * SEC_CONV) >> SCALE; 227 * 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). 235 * 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 2 241 * mpys). 242 243 * 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. 246 247 */ 248 249/* 250 * Here are the scales we will use. One for seconds, nanoseconds and 251 * microseconds. 252 * 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. 258 259 * Limits of cpp (for #if expressions) only long (no long long), but 260 * then we only need the most signicant bit. 261 */ 262 263#define SEC_JIFFIE_SC (31 - SHIFT_HZ) 264#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) 265#undef SEC_JIFFIE_SC 266#define SEC_JIFFIE_SC (32 - SHIFT_HZ) 267#endif 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)) 271 272#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ 273 TICK_NSEC -1) / (u64)TICK_NSEC)) 274/* 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. 278 */ 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) 285 286#endif 287 288/* 289 * Convert various time units to each other: 290 */ 291extern unsigned int jiffies_to_msecs(const unsigned long j); 292extern unsigned int jiffies_to_usecs(const unsigned long j); 293 294static inline u64 jiffies_to_nsecs(const unsigned long j) 295{ 296 return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; 297} 298 299extern u64 jiffies64_to_nsecs(u64 j); 300 301extern 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 */ 308static 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 */ 319static 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 */ 330static 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 */ 363static __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 374extern unsigned long __usecs_to_jiffies(const unsigned int u); 375#if !(USEC_PER_SEC % HZ) 376static 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 381static 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 */ 410static __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 421extern unsigned long timespec64_to_jiffies(const struct timespec64 *value); 422extern void jiffies_to_timespec64(const unsigned long jiffies, 423 struct timespec64 *value); 424static inline unsigned long timespec_to_jiffies(const struct timespec *value) 425{ 426 struct timespec64 ts = timespec_to_timespec64(*value); 427 428 return timespec64_to_jiffies(&ts); 429} 430 431static inline void jiffies_to_timespec(const unsigned long jiffies, 432 struct timespec *value) 433{ 434 struct timespec64 ts; 435 436 jiffies_to_timespec64(jiffies, &ts); 437 *value = timespec64_to_timespec(ts); 438} 439 440extern unsigned long timeval_to_jiffies(const struct timeval *value); 441extern void jiffies_to_timeval(const unsigned long jiffies, 442 struct timeval *value); 443 444extern clock_t jiffies_to_clock_t(unsigned long x); 445static inline clock_t jiffies_delta_to_clock_t(long delta) 446{ 447 return jiffies_to_clock_t(max(0L, delta)); 448} 449 450static inline unsigned int jiffies_delta_to_msecs(long delta) 451{ 452 return jiffies_to_msecs(max(0L, delta)); 453} 454 455extern unsigned long clock_t_to_jiffies(unsigned long x); 456extern u64 jiffies_64_to_clock_t(u64 x); 457extern u64 nsec_to_clock_t(u64 x); 458extern u64 nsecs_to_jiffies64(u64 n); 459extern unsigned long nsecs_to_jiffies(u64 n); 460 461#define TIMESTAMP_SIZE 30 462 463#endif 464