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 | |

60 | extern 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 | */ |

80 | extern u64 __cacheline_aligned_in_smp jiffies_64; |

81 | extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; |

82 | |

83 | #if (BITS_PER_LONG < 64) |

84 | u64 get_jiffies_64(void); |

85 | #else |

86 | static 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 | |

190 | extern 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 | */ |

291 | extern unsigned int jiffies_to_msecs(const unsigned long j); |

292 | extern unsigned int jiffies_to_usecs(const unsigned long j); |

293 | |

294 | static inline u64 jiffies_to_nsecs(const unsigned long j) |

295 | { |

296 | return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; |

297 | } |

298 | |

299 | extern u64 jiffies64_to_nsecs(u64 j); |

300 | |

301 | extern 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 | */ |

308 | static 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 | */ |

319 | static 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 | */ |

330 | static 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 | */ |

363 | static __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 | |

374 | extern unsigned long __usecs_to_jiffies(const unsigned int u); |

375 | #if !(USEC_PER_SEC % HZ) |

376 | static 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 |

381 | static 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 | */ |

410 | static __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 | |

421 | extern unsigned long timespec64_to_jiffies(const struct timespec64 *value); |

422 | extern void jiffies_to_timespec64(const unsigned long jiffies, |

423 | struct timespec64 *value); |

424 | static 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 | |

431 | static 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 | |

440 | extern unsigned long timeval_to_jiffies(const struct timeval *value); |

441 | extern void jiffies_to_timeval(const unsigned long jiffies, |

442 | struct timeval *value); |

443 | |

444 | extern clock_t jiffies_to_clock_t(unsigned long x); |

445 | static inline clock_t jiffies_delta_to_clock_t(long delta) |

446 | { |

447 | return jiffies_to_clock_t(max(0L, delta)); |

448 | } |

449 | |

450 | static inline unsigned int jiffies_delta_to_msecs(long delta) |

451 | { |

452 | return jiffies_to_msecs(max(0L, delta)); |

453 | } |

454 | |

455 | extern unsigned long clock_t_to_jiffies(unsigned long x); |

456 | extern u64 jiffies_64_to_clock_t(u64 x); |

457 | extern u64 nsec_to_clock_t(u64 x); |

458 | extern u64 nsecs_to_jiffies64(u64 n); |

459 | extern unsigned long nsecs_to_jiffies(u64 n); |

460 | |

461 | #define TIMESTAMP_SIZE 30 |

462 | |

463 | #endif |

464 |