1#ifndef _LINUX_JIFFIES_H 2#define _LINUX_JIFFIES_H 3 4#include <linux/cache.h> 5#include <linux/math64.h> 6#include <linux/kernel.h> 7#include <linux/types.h> 8#include <linux/time.h> 9#include <linux/timex.h> 10#include <asm/param.h> /* for HZ */ 11#include <generated/timeconst.h> 12 13/* 14 * The following defines establish the engineering parameters of the PLL 15 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz 16 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the 17 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the 18 * nearest power of two in order to avoid hardware multiply operations. 19 */ 20#if HZ >= 12 && HZ < 24 21# define SHIFT_HZ 4 22#elif HZ >= 24 && HZ < 48 23# define SHIFT_HZ 5 24#elif HZ >= 48 && HZ < 96 25# define SHIFT_HZ 6 26#elif HZ >= 96 && HZ < 192 27# define SHIFT_HZ 7 28#elif HZ >= 192 && HZ < 384 29# define SHIFT_HZ 8 30#elif HZ >= 384 && HZ < 768 31# define SHIFT_HZ 9 32#elif HZ >= 768 && HZ < 1536 33# define SHIFT_HZ 10 34#elif HZ >= 1536 && HZ < 3072 35# define SHIFT_HZ 11 36#elif HZ >= 3072 && HZ < 6144 37# define SHIFT_HZ 12 38#elif HZ >= 6144 && HZ < 12288 39# define SHIFT_HZ 13 40#else 41# error Invalid value of HZ. 42#endif 43 44/* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can 45 * improve accuracy by shifting LSH bits, hence calculating: 46 * (NOM << LSH) / DEN 47 * This however means trouble for large NOM, because (NOM << LSH) may no 48 * longer fit in 32 bits. The following way of calculating this gives us 49 * some slack, under the following conditions: 50 * - (NOM / DEN) fits in (32 - LSH) bits. 51 * - (NOM % DEN) fits in (32 - LSH) bits. 52 */ 53#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ 54 + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) 55 56/* LATCH is used in the interval timer and ftape setup. */ 57#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ 58 59extern int register_refined_jiffies(long clock_tick_rate); 60 61/* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */ 62#define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ) 63 64/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ 65#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) 66 67#ifndef __jiffy_arch_data 68#define __jiffy_arch_data 69#endif 70 71/* 72 * The 64-bit value is not atomic - you MUST NOT read it 73 * without sampling the sequence number in jiffies_lock. 74 * get_jiffies_64() will do this for you as appropriate. 75 */ 76extern u64 __cacheline_aligned_in_smp jiffies_64; 77extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; 78 79#if (BITS_PER_LONG < 64) 80u64 get_jiffies_64(void); 81#else 82static inline u64 get_jiffies_64(void) 83{ 84 return (u64)jiffies; 85} 86#endif 87 88/* 89 * These inlines deal with timer wrapping correctly. You are 90 * strongly encouraged to use them 91 * 1. Because people otherwise forget 92 * 2. Because if the timer wrap changes in future you won't have to 93 * alter your driver code. 94 * 95 * time_after(a,b) returns true if the time a is after time b. 96 * 97 * Do this with "<0" and ">=0" to only test the sign of the result. A 98 * good compiler would generate better code (and a really good compiler 99 * wouldn't care). Gcc is currently neither. 100 */ 101#define time_after(a,b) \ 102 (typecheck(unsigned long, a) && \ 103 typecheck(unsigned long, b) && \ 104 ((long)((b) - (a)) < 0)) 105#define time_before(a,b) time_after(b,a) 106 107#define time_after_eq(a,b) \ 108 (typecheck(unsigned long, a) && \ 109 typecheck(unsigned long, b) && \ 110 ((long)((a) - (b)) >= 0)) 111#define time_before_eq(a,b) time_after_eq(b,a) 112 113/* 114 * Calculate whether a is in the range of [b, c]. 115 */ 116#define time_in_range(a,b,c) \ 117 (time_after_eq(a,b) && \ 118 time_before_eq(a,c)) 119 120/* 121 * Calculate whether a is in the range of [b, c). 122 */ 123#define time_in_range_open(a,b,c) \ 124 (time_after_eq(a,b) && \ 125 time_before(a,c)) 126 127/* Same as above, but does so with platform independent 64bit types. 128 * These must be used when utilizing jiffies_64 (i.e. return value of 129 * get_jiffies_64() */ 130#define time_after64(a,b) \ 131 (typecheck(__u64, a) && \ 132 typecheck(__u64, b) && \ 133 ((__s64)((b) - (a)) < 0)) 134#define time_before64(a,b) time_after64(b,a) 135 136#define time_after_eq64(a,b) \ 137 (typecheck(__u64, a) && \ 138 typecheck(__u64, b) && \ 139 ((__s64)((a) - (b)) >= 0)) 140#define time_before_eq64(a,b) time_after_eq64(b,a) 141 142#define time_in_range64(a, b, c) \ 143 (time_after_eq64(a, b) && \ 144 time_before_eq64(a, c)) 145 146/* 147 * These four macros compare jiffies and 'a' for convenience. 148 */ 149 150/* time_is_before_jiffies(a) return true if a is before jiffies */ 151#define time_is_before_jiffies(a) time_after(jiffies, a) 152#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), 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#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a) 157 158/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ 159#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) 160#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a) 161 162/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ 163#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) 164#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a) 165 166/* 167 * Have the 32 bit jiffies value wrap 5 minutes after boot 168 * so jiffies wrap bugs show up earlier. 169 */ 170#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) 171 172/* 173 * Change timeval to jiffies, trying to avoid the 174 * most obvious overflows.. 175 * 176 * And some not so obvious. 177 * 178 * Note that we don't want to return LONG_MAX, because 179 * for various timeout reasons we often end up having 180 * to wait "jiffies+1" in order to guarantee that we wait 181 * at _least_ "jiffies" - so "jiffies+1" had better still 182 * be positive. 183 */ 184#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) 185 186extern unsigned long preset_lpj; 187 188/* 189 * We want to do realistic conversions of time so we need to use the same 190 * values the update wall clock code uses as the jiffies size. This value 191 * is: TICK_NSEC (which is defined in timex.h). This 192 * is a constant and is in nanoseconds. We will use scaled math 193 * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and 194 * NSEC_JIFFIE_SC. Note that these defines contain nothing but 195 * constants and so are computed at compile time. SHIFT_HZ (computed in 196 * timex.h) adjusts the scaling for different HZ values. 197 198 * Scaled math??? What is that? 199 * 200 * Scaled math is a way to do integer math on values that would, 201 * otherwise, either overflow, underflow, or cause undesired div 202 * instructions to appear in the execution path. In short, we "scale" 203 * up the operands so they take more bits (more precision, less 204 * underflow), do the desired operation and then "scale" the result back 205 * by the same amount. If we do the scaling by shifting we avoid the 206 * costly mpy and the dastardly div instructions. 207 208 * Suppose, for example, we want to convert from seconds to jiffies 209 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The 210 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We 211 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we 212 * might calculate at compile time, however, the result will only have 213 * about 3-4 bits of precision (less for smaller values of HZ). 214 * 215 * So, we scale as follows: 216 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); 217 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; 218 * Then we make SCALE a power of two so: 219 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; 220 * Now we define: 221 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) 222 * jiff = (sec * SEC_CONV) >> SCALE; 223 * 224 * Often the math we use will expand beyond 32-bits so we tell C how to 225 * do this and pass the 64-bit result of the mpy through the ">> SCALE" 226 * which should take the result back to 32-bits. We want this expansion 227 * to capture as much precision as possible. At the same time we don't 228 * want to overflow so we pick the SCALE to avoid this. In this file, 229 * that means using a different scale for each range of HZ values (as 230 * defined in timex.h). 231 * 232 * For those who want to know, gcc will give a 64-bit result from a "*" 233 * operator if the result is a long long AND at least one of the 234 * operands is cast to long long (usually just prior to the "*" so as 235 * not to confuse it into thinking it really has a 64-bit operand, 236 * which, buy the way, it can do, but it takes more code and at least 2 237 * mpys). 238 239 * We also need to be aware that one second in nanoseconds is only a 240 * couple of bits away from overflowing a 32-bit word, so we MUST use 241 * 64-bits to get the full range time in nanoseconds. 242 243 */ 244 245/* 246 * Here are the scales we will use. One for seconds, nanoseconds and 247 * microseconds. 248 * 249 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and 250 * check if the sign bit is set. If not, we bump the shift count by 1. 251 * (Gets an extra bit of precision where we can use it.) 252 * We know it is set for HZ = 1024 and HZ = 100 not for 1000. 253 * Haven't tested others. 254 255 * Limits of cpp (for #if expressions) only long (no long long), but 256 * then we only need the most signicant bit. 257 */ 258 259#define SEC_JIFFIE_SC (31 - SHIFT_HZ) 260#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) 261#undef SEC_JIFFIE_SC 262#define SEC_JIFFIE_SC (32 - SHIFT_HZ) 263#endif 264#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) 265#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ 266 TICK_NSEC -1) / (u64)TICK_NSEC)) 267 268#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ 269 TICK_NSEC -1) / (u64)TICK_NSEC)) 270/* 271 * The maximum jiffie value is (MAX_INT >> 1). Here we translate that 272 * into seconds. The 64-bit case will overflow if we are not careful, 273 * so use the messy SH_DIV macro to do it. Still all constants. 274 */ 275#if BITS_PER_LONG < 64 276# define MAX_SEC_IN_JIFFIES \ 277 (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) 278#else /* take care of overflow on 64 bits machines */ 279# define MAX_SEC_IN_JIFFIES \ 280 (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) 281 282#endif 283 284/* 285 * Convert various time units to each other: 286 */ 287extern unsigned int jiffies_to_msecs(const unsigned long j); 288extern unsigned int jiffies_to_usecs(const unsigned long j); 289 290static inline u64 jiffies_to_nsecs(const unsigned long j) 291{ 292 return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; 293} 294 295extern u64 jiffies64_to_nsecs(u64 j); 296 297extern unsigned long __msecs_to_jiffies(const unsigned int m); 298#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) 299/* 300 * HZ is equal to or smaller than 1000, and 1000 is a nice round 301 * multiple of HZ, divide with the factor between them, but round 302 * upwards: 303 */ 304static inline unsigned long _msecs_to_jiffies(const unsigned int m) 305{ 306 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); 307} 308#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) 309/* 310 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 - 311 * simply multiply with the factor between them. 312 * 313 * But first make sure the multiplication result cannot overflow: 314 */ 315static inline unsigned long _msecs_to_jiffies(const unsigned int m) 316{ 317 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) 318 return MAX_JIFFY_OFFSET; 319 return m * (HZ / MSEC_PER_SEC); 320} 321#else 322/* 323 * Generic case - multiply, round and divide. But first check that if 324 * we are doing a net multiplication, that we wouldn't overflow: 325 */ 326static inline unsigned long _msecs_to_jiffies(const unsigned int m) 327{ 328 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) 329 return MAX_JIFFY_OFFSET; 330 331 return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32; 332} 333#endif 334/** 335 * msecs_to_jiffies: - convert milliseconds to jiffies 336 * @m: time in milliseconds 337 * 338 * conversion is done as follows: 339 * 340 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) 341 * 342 * - 'too large' values [that would result in larger than 343 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. 344 * 345 * - all other values are converted to jiffies by either multiplying 346 * the input value by a factor or dividing it with a factor and 347 * handling any 32-bit overflows. 348 * for the details see __msecs_to_jiffies() 349 * 350 * msecs_to_jiffies() checks for the passed in value being a constant 351 * via __builtin_constant_p() allowing gcc to eliminate most of the 352 * code, __msecs_to_jiffies() is called if the value passed does not 353 * allow constant folding and the actual conversion must be done at 354 * runtime. 355 * the HZ range specific helpers _msecs_to_jiffies() are called both 356 * directly here and from __msecs_to_jiffies() in the case where 357 * constant folding is not possible. 358 */ 359static __always_inline unsigned long msecs_to_jiffies(const unsigned int m) 360{ 361 if (__builtin_constant_p(m)) { 362 if ((int)m < 0) 363 return MAX_JIFFY_OFFSET; 364 return _msecs_to_jiffies(m); 365 } else { 366 return __msecs_to_jiffies(m); 367 } 368} 369 370extern unsigned long __usecs_to_jiffies(const unsigned int u); 371#if !(USEC_PER_SEC % HZ) 372static inline unsigned long _usecs_to_jiffies(const unsigned int u) 373{ 374 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); 375} 376#else 377static inline unsigned long _usecs_to_jiffies(const unsigned int u) 378{ 379 return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) 380 >> USEC_TO_HZ_SHR32; 381} 382#endif 383 384/** 385 * usecs_to_jiffies: - convert microseconds to jiffies 386 * @u: time in microseconds 387 * 388 * conversion is done as follows: 389 * 390 * - 'too large' values [that would result in larger than 391 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. 392 * 393 * - all other values are converted to jiffies by either multiplying 394 * the input value by a factor or dividing it with a factor and 395 * handling any 32-bit overflows as for msecs_to_jiffies. 396 * 397 * usecs_to_jiffies() checks for the passed in value being a constant 398 * via __builtin_constant_p() allowing gcc to eliminate most of the 399 * code, __usecs_to_jiffies() is called if the value passed does not 400 * allow constant folding and the actual conversion must be done at 401 * runtime. 402 * the HZ range specific helpers _usecs_to_jiffies() are called both 403 * directly here and from __msecs_to_jiffies() in the case where 404 * constant folding is not possible. 405 */ 406static __always_inline unsigned long usecs_to_jiffies(const unsigned int u) 407{ 408 if (__builtin_constant_p(u)) { 409 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) 410 return MAX_JIFFY_OFFSET; 411 return _usecs_to_jiffies(u); 412 } else { 413 return __usecs_to_jiffies(u); 414 } 415} 416 417extern unsigned long timespec64_to_jiffies(const struct timespec64 *value); 418extern void jiffies_to_timespec64(const unsigned long jiffies, 419 struct timespec64 *value); 420static inline unsigned long timespec_to_jiffies(const struct timespec *value) 421{ 422 struct timespec64 ts = timespec_to_timespec64(*value); 423 424 return timespec64_to_jiffies(&ts); 425} 426 427static inline void jiffies_to_timespec(const unsigned long jiffies, 428 struct timespec *value) 429{ 430 struct timespec64 ts; 431 432 jiffies_to_timespec64(jiffies, &ts); 433 *value = timespec64_to_timespec(ts); 434} 435 436extern unsigned long timeval_to_jiffies(const struct timeval *value); 437extern void jiffies_to_timeval(const unsigned long jiffies, 438 struct timeval *value); 439 440extern clock_t jiffies_to_clock_t(unsigned long x); 441static inline clock_t jiffies_delta_to_clock_t(long delta) 442{ 443 return jiffies_to_clock_t(max(0L, delta)); 444} 445 446extern unsigned long clock_t_to_jiffies(unsigned long x); 447extern u64 jiffies_64_to_clock_t(u64 x); 448extern u64 nsec_to_clock_t(u64 x); 449extern u64 nsecs_to_jiffies64(u64 n); 450extern unsigned long nsecs_to_jiffies(u64 n); 451 452#define TIMESTAMP_SIZE 30 453 454#endif 455