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