1/* Modified by Broadcom Corp. Portions Copyright (c) Broadcom Corp, 2012. */ 2#ifndef _LINUX_JIFFIES_H 3#define _LINUX_JIFFIES_H 4 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 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 < 3 20# define SHIFT_HZ 1 21#elif HZ >= 3 && HZ < 6 22# define SHIFT_HZ 2 23#elif HZ >= 6 && HZ < 12 24# define SHIFT_HZ 3 25#elif HZ >= 12 && HZ < 24 26# define SHIFT_HZ 4 27#elif HZ >= 24 && HZ < 48 28# define SHIFT_HZ 5 29#elif HZ >= 48 && HZ < 96 30# define SHIFT_HZ 6 31#elif HZ >= 96 && HZ < 192 32# define SHIFT_HZ 7 33#elif HZ >= 192 && HZ < 384 34# define SHIFT_HZ 8 35#elif HZ >= 384 && HZ < 768 36# define SHIFT_HZ 9 37#elif HZ >= 768 && HZ < 1536 38# define SHIFT_HZ 10 39#elif HZ >= 1536 && HZ < 3072 40# define SHIFT_HZ 11 41#elif HZ >= 3072 && HZ < 6144 42# define SHIFT_HZ 12 43#elif HZ >= 6144 && HZ < 12288 44# define SHIFT_HZ 13 45#else 46# error Invalid value of HZ. 47#endif 48 49/* LATCH is used in the interval timer and ftape setup. */ 50#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ 51 52/* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, then we can 53 * improve accuracy by shifting LSH bits, hence calculating: 54 * (NOM << LSH) / DEN 55 * This however means trouble for large NOM, because (NOM << LSH) may no 56 * longer fit in 32 bits. The following way of calculating this gives us 57 * some slack, under the following conditions: 58 * - (NOM / DEN) fits in (32 - LSH) bits. 59 * - (NOM % DEN) fits in (32 - LSH) bits. 60 */ 61#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ 62 + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) 63 64/* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */ 65#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8)) 66 67/* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */ 68#define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8)) 69 70/* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ 71#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) 72 73/* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and */ 74/* a value TUSEC for TICK_USEC (can be set bij adjtimex) */ 75#define TICK_USEC_TO_NSEC(TUSEC) (SH_DIV (TUSEC * USER_HZ * 1000, ACTHZ, 8)) 76 77/* some arch's have a small-data section that can be accessed register-relative 78 * but that can only take up to, say, 4-byte variables. jiffies being part of 79 * an 8-byte variable may not be correctly accessed unless we force the issue 80 */ 81#define __jiffy_data __attribute__((section(".data"))) 82 83/* 84 * The 64-bit value is not atomic - you MUST NOT read it 85 * without sampling the sequence number in xtime_lock. 86 * get_jiffies_64() will do this for you as appropriate. 87 */ 88extern u64 __jiffy_data jiffies_64; 89extern unsigned long volatile __jiffy_data jiffies; 90 91#if (BITS_PER_LONG < 64) 92u64 get_jiffies_64(void); 93#else 94static inline u64 get_jiffies_64(void) 95{ 96 return (u64)jiffies; 97} 98#endif 99 100/* 101 * These inlines deal with timer wrapping correctly. You are 102 * strongly encouraged to use them 103 * 1. Because people otherwise forget 104 * 2. Because if the timer wrap changes in future you won't have to 105 * alter your driver code. 106 * 107 * time_after(a,b) returns true if the time a is after time b. 108 * 109 * Do this with "<0" and ">=0" to only test the sign of the result. A 110 * good compiler would generate better code (and a really good compiler 111 * wouldn't care). Gcc is currently neither. 112 */ 113#define time_after(a,b) \ 114 (typecheck(unsigned long, a) && \ 115 typecheck(unsigned long, b) && \ 116 ((long)(b) - (long)(a) < 0)) 117#define time_before(a,b) time_after(b,a) 118 119#define time_after_eq(a,b) \ 120 (typecheck(unsigned long, a) && \ 121 typecheck(unsigned long, b) && \ 122 ((long)(a) - (long)(b) >= 0)) 123#define time_before_eq(a,b) time_after_eq(b,a) 124 125/* 126 * Calculate whether a is in the range of [b, c]. 127 */ 128#define time_in_range(a,b,c) \ 129 (time_after_eq(a,b) && \ 130 time_before_eq(a,c)) 131 132/* 133 * Calculate whether a is in the range of [b, c). 134 */ 135#define time_in_range_open(a,b,c) \ 136 (time_after_eq(a,b) && \ 137 time_before(a,c)) 138 139/* Same as above, but does so with platform independent 64bit types. 140 * These must be used when utilizing jiffies_64 (i.e. return value of 141 * get_jiffies_64() */ 142#define time_after64(a,b) \ 143 (typecheck(__u64, a) && \ 144 typecheck(__u64, b) && \ 145 ((__s64)(b) - (__s64)(a) < 0)) 146#define time_before64(a,b) time_after64(b,a) 147 148#define time_after_eq64(a,b) \ 149 (typecheck(__u64, a) && \ 150 typecheck(__u64, b) && \ 151 ((__s64)(a) - (__s64)(b) >= 0)) 152#define time_before_eq64(a,b) time_after_eq64(b,a) 153 154/* 155 * These four macros compare jiffies and 'a' for convenience. 156 */ 157 158/* time_is_before_jiffies(a) return true if a is before jiffies */ 159#define time_is_before_jiffies(a) time_after(jiffies, a) 160 161/* time_is_after_jiffies(a) return true if a is after jiffies */ 162#define time_is_after_jiffies(a) time_before(jiffies, a) 163 164/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ 165#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) 166 167/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ 168#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, 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 USEC_JIFFIE_SC (SEC_JIFFIE_SC + 19) 270#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ 271 TICK_NSEC -1) / (u64)TICK_NSEC)) 272 273#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ 274 TICK_NSEC -1) / (u64)TICK_NSEC)) 275#define USEC_CONVERSION \ 276 ((unsigned long)((((u64)NSEC_PER_USEC << USEC_JIFFIE_SC) +\ 277 TICK_NSEC -1) / (u64)TICK_NSEC)) 278/* 279 * USEC_ROUND is used in the timeval to jiffie conversion. See there 280 * for more details. It is the scaled resolution rounding value. Note 281 * that it is a 64-bit value. Since, when it is applied, we are already 282 * in jiffies (albit scaled), it is nothing but the bits we will shift 283 * off. 284 */ 285#define USEC_ROUND (u64)(((u64)1 << USEC_JIFFIE_SC) - 1) 286/* 287 * The maximum jiffie value is (MAX_INT >> 1). Here we translate that 288 * into seconds. The 64-bit case will overflow if we are not careful, 289 * so use the messy SH_DIV macro to do it. Still all constants. 290 */ 291#if BITS_PER_LONG < 64 292# define MAX_SEC_IN_JIFFIES \ 293 (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) 294#else /* take care of overflow on 64 bits machines */ 295# define MAX_SEC_IN_JIFFIES \ 296 (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) 297 298#endif 299 300/* 301 * Convert various time units to each other: 302 */ 303extern unsigned int jiffies_to_msecs(const unsigned long j); 304extern unsigned int jiffies_to_usecs(const unsigned long j); 305extern unsigned long msecs_to_jiffies(const unsigned int m); 306extern unsigned long usecs_to_jiffies(const unsigned int u); 307extern unsigned long timespec_to_jiffies(const struct timespec *value); 308extern void jiffies_to_timespec(const unsigned long jiffies, 309 struct timespec *value); 310extern unsigned long timeval_to_jiffies(const struct timeval *value); 311extern void jiffies_to_timeval(const unsigned long jiffies, 312 struct timeval *value); 313extern clock_t jiffies_to_clock_t(long x); 314extern unsigned long clock_t_to_jiffies(unsigned long x); 315extern u64 jiffies_64_to_clock_t(u64 x); 316extern u64 nsec_to_clock_t(u64 x); 317extern unsigned long nsecs_to_jiffies(u64 n); 318 319#define TIMESTAMP_SIZE 30 320 321#endif 322