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/limits.h> |

7 | #include <linux/math64.h> |

8 | #include <linux/minmax.h> |

9 | #include <linux/types.h> |

10 | #include <linux/time.h> |

11 | #include <linux/timex.h> |

12 | #include <vdso/jiffies.h> |

13 | #include <asm/param.h> /* for HZ */ |

14 | #include <generated/timeconst.h> |

15 | |

16 | /* |

17 | * The following defines establish the engineering parameters of the PLL |

18 | * model. The HZ variable establishes the timer interrupt frequency, 100 Hz |

19 | * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the |

20 | * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the |

21 | * nearest power of two in order to avoid hardware multiply operations. |

22 | */ |

23 | #if HZ >= 12 && HZ < 24 |

24 | # define SHIFT_HZ 4 |

25 | #elif HZ >= 24 && HZ < 48 |

26 | # define SHIFT_HZ 5 |

27 | #elif HZ >= 48 && HZ < 96 |

28 | # define SHIFT_HZ 6 |

29 | #elif HZ >= 96 && HZ < 192 |

30 | # define SHIFT_HZ 7 |

31 | #elif HZ >= 192 && HZ < 384 |

32 | # define SHIFT_HZ 8 |

33 | #elif HZ >= 384 && HZ < 768 |

34 | # define SHIFT_HZ 9 |

35 | #elif HZ >= 768 && HZ < 1536 |

36 | # define SHIFT_HZ 10 |

37 | #elif HZ >= 1536 && HZ < 3072 |

38 | # define SHIFT_HZ 11 |

39 | #elif HZ >= 3072 && HZ < 6144 |

40 | # define SHIFT_HZ 12 |

41 | #elif HZ >= 6144 && HZ < 12288 |

42 | # define SHIFT_HZ 13 |

43 | #else |

44 | # error Invalid value of HZ. |

45 | #endif |

46 | |

47 | /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can |

48 | * improve accuracy by shifting LSH bits, hence calculating: |

49 | * (NOM << LSH) / DEN |

50 | * This however means trouble for large NOM, because (NOM << LSH) may no |

51 | * longer fit in 32 bits. The following way of calculating this gives us |

52 | * some slack, under the following conditions: |

53 | * - (NOM / DEN) fits in (32 - LSH) bits. |

54 | * - (NOM % DEN) fits in (32 - LSH) bits. |

55 | */ |

56 | #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ |

57 | + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) |

58 | |

59 | /* LATCH is used in the interval timer and ftape setup. */ |

60 | #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ |

61 | |

62 | extern int register_refined_jiffies(long clock_tick_rate); |

63 | |

64 | /* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */ |

65 | #define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ) |

66 | |

67 | /* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ |

68 | #define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) |

69 | |

70 | #ifndef __jiffy_arch_data |

71 | #define __jiffy_arch_data |

72 | #endif |

73 | |

74 | /* |

75 | * The 64-bit value is not atomic - you MUST NOT read it |

76 | * without sampling the sequence number in jiffies_lock. |

77 | * get_jiffies_64() will do this for you as appropriate. |

78 | */ |

79 | extern u64 __cacheline_aligned_in_smp jiffies_64; |

80 | extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; |

81 | |

82 | #if (BITS_PER_LONG < 64) |

83 | u64 get_jiffies_64(void); |

84 | #else |

85 | static inline u64 get_jiffies_64(void) |

86 | { |

87 | return (u64)jiffies; |

88 | } |

89 | #endif |

90 | |

91 | /* |

92 | * These inlines deal with timer wrapping correctly. You are |

93 | * strongly encouraged to use them |

94 | * 1. Because people otherwise forget |

95 | * 2. Because if the timer wrap changes in future you won't have to |

96 | * alter your driver code. |

97 | * |

98 | * time_after(a,b) returns true if the time a is after time b. |

99 | * |

100 | * Do this with "<0" and ">=0" to only test the sign of the result. A |

101 | * good compiler would generate better code (and a really good compiler |

102 | * wouldn't care). Gcc is currently neither. |

103 | */ |

104 | #define time_after(a,b) \ |

105 | (typecheck(unsigned long, a) && \ |

106 | typecheck(unsigned long, b) && \ |

107 | ((long)((b) - (a)) < 0)) |

108 | #define time_before(a,b) time_after(b,a) |

109 | |

110 | #define time_after_eq(a,b) \ |

111 | (typecheck(unsigned long, a) && \ |

112 | typecheck(unsigned long, b) && \ |

113 | ((long)((a) - (b)) >= 0)) |

114 | #define time_before_eq(a,b) time_after_eq(b,a) |

115 | |

116 | /* |

117 | * Calculate whether a is in the range of [b, c]. |

118 | */ |

119 | #define time_in_range(a,b,c) \ |

120 | (time_after_eq(a,b) && \ |

121 | time_before_eq(a,c)) |

122 | |

123 | /* |

124 | * Calculate whether a is in the range of [b, c). |

125 | */ |

126 | #define time_in_range_open(a,b,c) \ |

127 | (time_after_eq(a,b) && \ |

128 | time_before(a,c)) |

129 | |

130 | /* Same as above, but does so with platform independent 64bit types. |

131 | * These must be used when utilizing jiffies_64 (i.e. return value of |

132 | * get_jiffies_64() */ |

133 | #define time_after64(a,b) \ |

134 | (typecheck(__u64, a) && \ |

135 | typecheck(__u64, b) && \ |

136 | ((__s64)((b) - (a)) < 0)) |

137 | #define time_before64(a,b) time_after64(b,a) |

138 | |

139 | #define time_after_eq64(a,b) \ |

140 | (typecheck(__u64, a) && \ |

141 | typecheck(__u64, b) && \ |

142 | ((__s64)((a) - (b)) >= 0)) |

143 | #define time_before_eq64(a,b) time_after_eq64(b,a) |

144 | |

145 | #define time_in_range64(a, b, c) \ |

146 | (time_after_eq64(a, b) && \ |

147 | time_before_eq64(a, c)) |

148 | |

149 | /* |

150 | * These four macros compare jiffies and 'a' for convenience. |

151 | */ |

152 | |

153 | /* time_is_before_jiffies(a) return true if a is before jiffies */ |

154 | #define time_is_before_jiffies(a) time_after(jiffies, a) |

155 | #define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a) |

156 | |

157 | /* time_is_after_jiffies(a) return true if a is after jiffies */ |

158 | #define time_is_after_jiffies(a) time_before(jiffies, a) |

159 | #define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a) |

160 | |

161 | /* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ |

162 | #define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) |

163 | #define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a) |

164 | |

165 | /* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ |

166 | #define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) |

167 | #define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a) |

168 | |

169 | /* |

170 | * Have the 32 bit jiffies value wrap 5 minutes after boot |

171 | * so jiffies wrap bugs show up earlier. |

172 | */ |

173 | #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) |

174 | |

175 | /* |

176 | * Change timeval to jiffies, trying to avoid the |

177 | * most obvious overflows.. |

178 | * |

179 | * And some not so obvious. |

180 | * |

181 | * Note that we don't want to return LONG_MAX, because |

182 | * for various timeout reasons we often end up having |

183 | * to wait "jiffies+1" in order to guarantee that we wait |

184 | * at _least_ "jiffies" - so "jiffies+1" had better still |

185 | * be positive. |

186 | */ |

187 | #define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) |

188 | |

189 | extern unsigned long preset_lpj; |

190 | |

191 | /* |

192 | * We want to do realistic conversions of time so we need to use the same |

193 | * values the update wall clock code uses as the jiffies size. This value |

194 | * is: TICK_NSEC (which is defined in timex.h). This |

195 | * is a constant and is in nanoseconds. We will use scaled math |

196 | * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and |

197 | * NSEC_JIFFIE_SC. Note that these defines contain nothing but |

198 | * constants and so are computed at compile time. SHIFT_HZ (computed in |

199 | * timex.h) adjusts the scaling for different HZ values. |

200 | |

201 | * Scaled math??? What is that? |

202 | * |

203 | * Scaled math is a way to do integer math on values that would, |

204 | * otherwise, either overflow, underflow, or cause undesired div |

205 | * instructions to appear in the execution path. In short, we "scale" |

206 | * up the operands so they take more bits (more precision, less |

207 | * underflow), do the desired operation and then "scale" the result back |

208 | * by the same amount. If we do the scaling by shifting we avoid the |

209 | * costly mpy and the dastardly div instructions. |

210 | |

211 | * Suppose, for example, we want to convert from seconds to jiffies |

212 | * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The |

213 | * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We |

214 | * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we |

215 | * might calculate at compile time, however, the result will only have |

216 | * about 3-4 bits of precision (less for smaller values of HZ). |

217 | * |

218 | * So, we scale as follows: |

219 | * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); |

220 | * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; |

221 | * Then we make SCALE a power of two so: |

222 | * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; |

223 | * Now we define: |

224 | * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) |

225 | * jiff = (sec * SEC_CONV) >> SCALE; |

226 | * |

227 | * Often the math we use will expand beyond 32-bits so we tell C how to |

228 | * do this and pass the 64-bit result of the mpy through the ">> SCALE" |

229 | * which should take the result back to 32-bits. We want this expansion |

230 | * to capture as much precision as possible. At the same time we don't |

231 | * want to overflow so we pick the SCALE to avoid this. In this file, |

232 | * that means using a different scale for each range of HZ values (as |

233 | * defined in timex.h). |

234 | * |

235 | * For those who want to know, gcc will give a 64-bit result from a "*" |

236 | * operator if the result is a long long AND at least one of the |

237 | * operands is cast to long long (usually just prior to the "*" so as |

238 | * not to confuse it into thinking it really has a 64-bit operand, |

239 | * which, buy the way, it can do, but it takes more code and at least 2 |

240 | * mpys). |

241 | |

242 | * We also need to be aware that one second in nanoseconds is only a |

243 | * couple of bits away from overflowing a 32-bit word, so we MUST use |

244 | * 64-bits to get the full range time in nanoseconds. |

245 | |

246 | */ |

247 | |

248 | /* |

249 | * Here are the scales we will use. One for seconds, nanoseconds and |

250 | * microseconds. |

251 | * |

252 | * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and |

253 | * check if the sign bit is set. If not, we bump the shift count by 1. |

254 | * (Gets an extra bit of precision where we can use it.) |

255 | * We know it is set for HZ = 1024 and HZ = 100 not for 1000. |

256 | * Haven't tested others. |

257 | |

258 | * Limits of cpp (for #if expressions) only long (no long long), but |

259 | * then we only need the most signicant bit. |

260 | */ |

261 | |

262 | #define SEC_JIFFIE_SC (31 - SHIFT_HZ) |

263 | #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) |

264 | #undef SEC_JIFFIE_SC |

265 | #define SEC_JIFFIE_SC (32 - SHIFT_HZ) |

266 | #endif |

267 | #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) |

268 | #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ |

269 | TICK_NSEC -1) / (u64)TICK_NSEC)) |

270 | |

271 | #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ |

272 | TICK_NSEC -1) / (u64)TICK_NSEC)) |

273 | /* |

274 | * The maximum jiffie value is (MAX_INT >> 1). Here we translate that |

275 | * into seconds. The 64-bit case will overflow if we are not careful, |

276 | * so use the messy SH_DIV macro to do it. Still all constants. |

277 | */ |

278 | #if BITS_PER_LONG < 64 |

279 | # define MAX_SEC_IN_JIFFIES \ |

280 | (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) |

281 | #else /* take care of overflow on 64 bits machines */ |

282 | # define MAX_SEC_IN_JIFFIES \ |

283 | (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) |

284 | |

285 | #endif |

286 | |

287 | /* |

288 | * Convert various time units to each other: |

289 | */ |

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

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

292 | |

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

294 | { |

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

296 | } |

297 | |

298 | extern u64 jiffies64_to_nsecs(u64 j); |

299 | extern u64 jiffies64_to_msecs(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 | extern clock_t jiffies_to_clock_t(unsigned long x); |

425 | static inline clock_t jiffies_delta_to_clock_t(long delta) |

426 | { |

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

428 | } |

429 | |

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

431 | { |

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

433 | } |

434 | |

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

436 | extern u64 jiffies_64_to_clock_t(u64 x); |

437 | extern u64 nsec_to_clock_t(u64 x); |

438 | extern u64 nsecs_to_jiffies64(u64 n); |

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

440 | |

441 | #define TIMESTAMP_SIZE 30 |

442 | |

443 | #endif |

444 |