1 /* $NetBSD: subr_cpufreq.c,v 1.11 2026/01/04 03:15:28 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jukka Ruohonen. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 #include <sys/cdefs.h> 33 __KERNEL_RCSID(0, "$NetBSD: subr_cpufreq.c,v 1.11 2026/01/04 03:15:28 riastradh Exp $"); 34 35 #include <sys/param.h> 36 #include <sys/cpu.h> 37 #include <sys/cpufreq.h> 38 #include <sys/kernel.h> 39 #include <sys/kmem.h> 40 #include <sys/mutex.h> 41 #include <sys/sdt.h> 42 #include <sys/time.h> 43 #include <sys/xcall.h> 44 45 static int cpufreq_latency(void); 46 static uint32_t cpufreq_get_max(void); 47 static uint32_t cpufreq_get_min(void); 48 static uint32_t cpufreq_get_raw(struct cpu_info *); 49 static void cpufreq_get_state_raw(uint32_t, struct cpufreq_state *); 50 static void cpufreq_set_raw(struct cpu_info *, uint32_t); 51 static void cpufreq_set_all_raw(uint32_t); 52 53 static kmutex_t cpufreq_lock __cacheline_aligned; 54 static struct cpufreq *cf_backend __read_mostly = NULL; 55 56 void 57 cpufreq_init(void) 58 { 59 60 mutex_init(&cpufreq_lock, MUTEX_DEFAULT, IPL_NONE); 61 cf_backend = kmem_zalloc(sizeof(*cf_backend), KM_SLEEP); 62 } 63 64 int 65 cpufreq_register(struct cpufreq *cf) 66 { 67 uint32_t c, i, j, k, m; 68 int rv; 69 70 if (cold != 0) 71 return SET_ERROR(EBUSY); 72 73 KASSERT(cf != NULL); 74 KASSERT(cf_backend != NULL); 75 KASSERT(cf->cf_get_freq != NULL); 76 KASSERT(cf->cf_set_freq != NULL); 77 KASSERT(cf->cf_state_count > 0); 78 KASSERT(cf->cf_state_count < CPUFREQ_STATE_MAX); 79 80 mutex_enter(&cpufreq_lock); 81 82 if (cf_backend->cf_init != false) { 83 mutex_exit(&cpufreq_lock); 84 return SET_ERROR(EALREADY); 85 } 86 87 cf_backend->cf_init = true; 88 cf_backend->cf_mp = cf->cf_mp; 89 cf_backend->cf_cookie = cf->cf_cookie; 90 cf_backend->cf_get_freq = cf->cf_get_freq; 91 cf_backend->cf_set_freq = cf->cf_set_freq; 92 93 (void)strlcpy(cf_backend->cf_name, cf->cf_name, sizeof(cf->cf_name)); 94 95 /* 96 * Sanity check the values and verify descending order. 97 */ 98 for (c = i = 0; i < cf->cf_state_count; i++) { 99 100 CTASSERT(CPUFREQ_STATE_ENABLED != 0); 101 CTASSERT(CPUFREQ_STATE_DISABLED != 0); 102 103 if (cf->cf_state[i].cfs_freq == 0) 104 continue; 105 106 if (cf->cf_state[i].cfs_freq > 9999 && 107 cf->cf_state[i].cfs_freq != CPUFREQ_STATE_ENABLED && 108 cf->cf_state[i].cfs_freq != CPUFREQ_STATE_DISABLED) 109 continue; 110 111 for (j = k = 0; j < i; j++) { 112 113 if (cf->cf_state[i].cfs_freq >= 114 cf->cf_state[j].cfs_freq) { 115 k = 1; 116 break; 117 } 118 } 119 120 if (k != 0) 121 continue; 122 123 cf_backend->cf_state[c].cfs_index = c; 124 cf_backend->cf_state[c].cfs_freq = cf->cf_state[i].cfs_freq; 125 cf_backend->cf_state[c].cfs_power = cf->cf_state[i].cfs_power; 126 127 c++; 128 } 129 130 cf_backend->cf_state_count = c; 131 132 if (cf_backend->cf_state_count == 0) { 133 mutex_exit(&cpufreq_lock); 134 cpufreq_deregister(); 135 return SET_ERROR(EINVAL); 136 } 137 138 rv = cpufreq_latency(); 139 140 if (rv != 0) { 141 mutex_exit(&cpufreq_lock); 142 cpufreq_deregister(); 143 return rv; 144 } 145 146 m = cpufreq_get_max(); 147 cpufreq_set_all_raw(m); 148 mutex_exit(&cpufreq_lock); 149 150 return 0; 151 } 152 153 void 154 cpufreq_deregister(void) 155 { 156 157 mutex_enter(&cpufreq_lock); 158 memset(cf_backend, 0, sizeof(*cf_backend)); 159 mutex_exit(&cpufreq_lock); 160 } 161 162 static int 163 cpufreq_latency(void) 164 { 165 struct cpufreq *cf = cf_backend; 166 struct timespec nta, ntb; 167 const uint32_t n = 10; 168 uint32_t i, j, l, m; 169 uint64_t s; 170 171 l = cpufreq_get_min(); 172 m = cpufreq_get_max(); 173 174 /* 175 * For each state, sample the average transition 176 * latency required to set the state for all CPUs. 177 */ 178 for (i = 0; i < cf->cf_state_count; i++) { 179 180 for (s = 0, j = 0; j < n; j++) { 181 182 /* 183 * Attempt to exclude possible 184 * caching done by the backend. 185 */ 186 if (i == 0) 187 cpufreq_set_all_raw(l); 188 else { 189 cpufreq_set_all_raw(m); 190 } 191 192 nanotime(&nta); 193 cpufreq_set_all_raw(cf->cf_state[i].cfs_freq); 194 nanotime(&ntb); 195 timespecsub(&ntb, &nta, &ntb); 196 197 if (ntb.tv_sec != 0 || 198 ntb.tv_nsec > CPUFREQ_LATENCY_MAX) 199 continue; 200 201 if (s >= UINT64_MAX - CPUFREQ_LATENCY_MAX) 202 break; 203 204 /* Convert to microseconds to prevent overflow */ 205 s += ntb.tv_nsec / 1000; 206 } 207 208 /* 209 * Consider the backend unsuitable if 210 * the transition latency was too high. 211 */ 212 if (s == 0) 213 return SET_ERROR(EMSGSIZE); 214 215 cf->cf_state[i].cfs_latency = s / n; 216 } 217 218 return 0; 219 } 220 221 void 222 cpufreq_suspend(struct cpu_info *ci) 223 { 224 struct cpufreq *cf = cf_backend; 225 uint32_t l, s; 226 227 mutex_enter(&cpufreq_lock); 228 229 if (cf->cf_init != true) { 230 mutex_exit(&cpufreq_lock); 231 return; 232 } 233 234 l = cpufreq_get_min(); 235 s = cpufreq_get_raw(ci); 236 237 cpufreq_set_raw(ci, l); 238 cf->cf_state_saved = s; 239 240 mutex_exit(&cpufreq_lock); 241 } 242 243 void 244 cpufreq_resume(struct cpu_info *ci) 245 { 246 struct cpufreq *cf = cf_backend; 247 248 mutex_enter(&cpufreq_lock); 249 250 if (cf->cf_init != true || cf->cf_state_saved == 0) { 251 mutex_exit(&cpufreq_lock); 252 return; 253 } 254 255 cpufreq_set_raw(ci, cf->cf_state_saved); 256 mutex_exit(&cpufreq_lock); 257 } 258 259 uint32_t 260 cpufreq_get(struct cpu_info *ci) 261 { 262 struct cpufreq *cf = cf_backend; 263 uint32_t freq; 264 265 mutex_enter(&cpufreq_lock); 266 267 if (cf->cf_init != true) { 268 mutex_exit(&cpufreq_lock); 269 return 0; 270 } 271 272 freq = cpufreq_get_raw(ci); 273 mutex_exit(&cpufreq_lock); 274 275 return freq; 276 } 277 278 static uint32_t 279 cpufreq_get_max(void) 280 { 281 struct cpufreq *cf = cf_backend; 282 283 KASSERT(cf->cf_init != false); 284 KASSERT(mutex_owned(&cpufreq_lock) != 0); 285 286 return cf->cf_state[0].cfs_freq; 287 } 288 289 static uint32_t 290 cpufreq_get_min(void) 291 { 292 struct cpufreq *cf = cf_backend; 293 294 KASSERT(cf->cf_init != false); 295 KASSERT(mutex_owned(&cpufreq_lock) != 0); 296 297 return cf->cf_state[cf->cf_state_count - 1].cfs_freq; 298 } 299 300 static uint32_t 301 cpufreq_get_raw(struct cpu_info *ci) 302 { 303 struct cpufreq *cf = cf_backend; 304 uint32_t freq = 0; 305 uint64_t xc; 306 307 KASSERT(cf->cf_init != false); 308 KASSERT(mutex_owned(&cpufreq_lock) != 0); 309 310 xc = xc_unicast(0, (*cf->cf_get_freq), cf->cf_cookie, &freq, ci); 311 xc_wait(xc); 312 313 return freq; 314 } 315 316 int 317 cpufreq_get_backend(struct cpufreq *dst) 318 { 319 struct cpufreq *cf = cf_backend; 320 321 mutex_enter(&cpufreq_lock); 322 323 if (cf->cf_init != true || dst == NULL) { 324 mutex_exit(&cpufreq_lock); 325 return SET_ERROR(ENODEV); 326 } 327 328 memcpy(dst, cf, sizeof(*cf)); 329 mutex_exit(&cpufreq_lock); 330 331 return 0; 332 } 333 334 int 335 cpufreq_get_state(uint32_t freq, struct cpufreq_state *cfs) 336 { 337 struct cpufreq *cf = cf_backend; 338 339 mutex_enter(&cpufreq_lock); 340 341 if (cf->cf_init != true || cfs == NULL) { 342 mutex_exit(&cpufreq_lock); 343 return SET_ERROR(ENODEV); 344 } 345 346 cpufreq_get_state_raw(freq, cfs); 347 mutex_exit(&cpufreq_lock); 348 349 return 0; 350 } 351 352 int 353 cpufreq_get_state_index(uint32_t index, struct cpufreq_state *cfs) 354 { 355 struct cpufreq *cf = cf_backend; 356 357 mutex_enter(&cpufreq_lock); 358 359 if (cf->cf_init != true || cfs == NULL) { 360 mutex_exit(&cpufreq_lock); 361 return SET_ERROR(ENODEV); 362 } 363 364 if (index >= cf->cf_state_count) { 365 mutex_exit(&cpufreq_lock); 366 return SET_ERROR(EINVAL); 367 } 368 369 memcpy(cfs, &cf->cf_state[index], sizeof(*cfs)); 370 mutex_exit(&cpufreq_lock); 371 372 return 0; 373 } 374 375 static void 376 cpufreq_get_state_raw(uint32_t freq, struct cpufreq_state *cfs) 377 { 378 struct cpufreq *cf = cf_backend; 379 uint32_t f, hi, i = 0, lo = 0; 380 381 KASSERT(mutex_owned(&cpufreq_lock) != 0); 382 KASSERT(cf->cf_init != false); 383 KASSERT(cfs != NULL); 384 385 hi = cf->cf_state_count; 386 387 while (lo < hi) { 388 389 i = (lo + hi) >> 1; 390 f = cf->cf_state[i].cfs_freq; 391 392 if (freq == f) 393 break; 394 else if (freq > f) 395 hi = i; 396 else { 397 lo = i + 1; 398 } 399 } 400 401 memcpy(cfs, &cf->cf_state[i], sizeof(*cfs)); 402 } 403 404 void 405 cpufreq_set(struct cpu_info *ci, uint32_t freq) 406 { 407 struct cpufreq *cf = cf_backend; 408 409 mutex_enter(&cpufreq_lock); 410 411 if (__predict_false(cf->cf_init != true)) { 412 mutex_exit(&cpufreq_lock); 413 return; 414 } 415 416 cpufreq_set_raw(ci, freq); 417 mutex_exit(&cpufreq_lock); 418 } 419 420 static void 421 cpufreq_set_raw(struct cpu_info *ci, uint32_t freq) 422 { 423 struct cpufreq *cf = cf_backend; 424 uint64_t xc; 425 426 KASSERT(cf->cf_init != false); 427 KASSERT(mutex_owned(&cpufreq_lock) != 0); 428 429 xc = xc_unicast(0, (*cf->cf_set_freq), cf->cf_cookie, &freq, ci); 430 xc_wait(xc); 431 } 432 433 void 434 cpufreq_set_all(uint32_t freq) 435 { 436 struct cpufreq *cf = cf_backend; 437 438 mutex_enter(&cpufreq_lock); 439 440 if (__predict_false(cf->cf_init != true)) { 441 mutex_exit(&cpufreq_lock); 442 return; 443 } 444 445 cpufreq_set_all_raw(freq); 446 mutex_exit(&cpufreq_lock); 447 } 448 449 static void 450 cpufreq_set_all_raw(uint32_t freq) 451 { 452 struct cpufreq *cf = cf_backend; 453 uint64_t xc; 454 455 KASSERT(cf->cf_init != false); 456 KASSERT(mutex_owned(&cpufreq_lock) != 0); 457 458 xc = xc_broadcast(0, (*cf->cf_set_freq), cf->cf_cookie, &freq); 459 xc_wait(xc); 460 } 461 462 #ifdef notyet 463 void 464 cpufreq_set_higher(struct cpu_info *ci) 465 { 466 cpufreq_set_step(ci, -1); 467 } 468 469 void 470 cpufreq_set_lower(struct cpu_info *ci) 471 { 472 cpufreq_set_step(ci, 1); 473 } 474 475 static void 476 cpufreq_set_step(struct cpu_info *ci, int32_t step) 477 { 478 struct cpufreq *cf = cf_backend; 479 struct cpufreq_state cfs; 480 uint32_t freq; 481 int32_t index; 482 483 mutex_enter(&cpufreq_lock); 484 485 if (__predict_false(cf->cf_init != true)) { 486 mutex_exit(&cpufreq_lock); 487 return; 488 } 489 490 freq = cpufreq_get_raw(ci); 491 492 if (__predict_false(freq == 0)) { 493 mutex_exit(&cpufreq_lock); 494 return; 495 } 496 497 cpufreq_get_state_raw(freq, &cfs); 498 index = cfs.cfs_index + step; 499 500 if (index < 0 || index >= (int32_t)cf->cf_state_count) { 501 mutex_exit(&cpufreq_lock); 502 return; 503 } 504 505 cpufreq_set_raw(ci, cf->cf_state[index].cfs_freq); 506 mutex_exit(&cpufreq_lock); 507 } 508 #endif 509
Indexes created Sun Feb 22 08:20:21 UTC 2026