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