1 // SPDX-License-Identifier: GPL-2.0-only 2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 3 4 #include <linux/kernel.h> 5 #include <linux/sched.h> 6 #include <linux/sched/clock.h> 7 #include <linux/init.h> 8 #include <linux/export.h> 9 #include <linux/timer.h> 10 #include <linux/acpi_pmtmr.h> 11 #include <linux/cpufreq.h> 12 #include <linux/delay.h> 13 #include <linux/clocksource.h> 14 #include <linux/percpu.h> 15 #include <linux/timex.h> 16 #include <linux/static_key.h> 17 #include <linux/static_call.h> 18 19 #include <asm/hpet.h> 20 #include <asm/timer.h> 21 #include <asm/vgtod.h> 22 #include <asm/time.h> 23 #include <asm/delay.h> 24 #include <asm/hypervisor.h> 25 #include <asm/nmi.h> 26 #include <asm/x86_init.h> 27 #include <asm/geode.h> 28 #include <asm/apic.h> 29 #include <asm/intel-family.h> 30 #include <asm/i8259.h> 31 #include <asm/uv/uv.h> 32 33 unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */ 34 EXPORT_SYMBOL(cpu_khz); 35 36 unsigned int __read_mostly tsc_khz; 37 EXPORT_SYMBOL(tsc_khz); 38 39 #define KHZ 1000 40 41 /* 42 * TSC can be unstable due to cpufreq or due to unsynced TSCs 43 */ 44 static int __read_mostly tsc_unstable; 45 static unsigned int __initdata tsc_early_khz; 46 47 static DEFINE_STATIC_KEY_FALSE(__use_tsc); 48 49 int tsc_clocksource_reliable; 50 51 static u32 art_to_tsc_numerator; 52 static u32 art_to_tsc_denominator; 53 static u64 art_to_tsc_offset; 54 struct clocksource *art_related_clocksource; 55 56 struct cyc2ns { 57 struct cyc2ns_data data[2]; /* 0 + 2*16 = 32 */ 58 seqcount_latch_t seq; /* 32 + 4 = 36 */ 59 60 }; /* fits one cacheline */ 61 62 static DEFINE_PER_CPU_ALIGNED(struct cyc2ns, cyc2ns); 63 64 static int __init tsc_early_khz_setup(char *buf) 65 { 66 return kstrtouint(buf, 0, &tsc_early_khz); 67 } 68 early_param("tsc_early_khz", tsc_early_khz_setup); 69 70 __always_inline void cyc2ns_read_begin(struct cyc2ns_data *data) 71 { 72 int seq, idx; 73 74 preempt_disable_notrace(); 75 76 do { 77 seq = this_cpu_read(cyc2ns.seq.seqcount.sequence); 78 idx = seq & 1; 79 80 data->cyc2ns_offset = this_cpu_read(cyc2ns.data[idx].cyc2ns_offset); 81 data->cyc2ns_mul = this_cpu_read(cyc2ns.data[idx].cyc2ns_mul); 82 data->cyc2ns_shift = this_cpu_read(cyc2ns.data[idx].cyc2ns_shift); 83 84 } while (unlikely(seq != this_cpu_read(cyc2ns.seq.seqcount.sequence))); 85 } 86 87 __always_inline void cyc2ns_read_end(void) 88 { 89 preempt_enable_notrace(); 90 } 91 92 /* 93 * Accelerators for sched_clock() 94 * convert from cycles(64bits) => nanoseconds (64bits) 95 * basic equation: 96 * ns = cycles / (freq / ns_per_sec) 97 * ns = cycles * (ns_per_sec / freq) 98 * ns = cycles * (10^9 / (cpu_khz * 10^3)) 99 * ns = cycles * (10^6 / cpu_khz) 100 * 101 * Then we use scaling math (suggested by george@mvista.com) to get: 102 * ns = cycles * (10^6 * SC / cpu_khz) / SC 103 * ns = cycles * cyc2ns_scale / SC 104 * 105 * And since SC is a constant power of two, we can convert the div 106 * into a shift. The larger SC is, the more accurate the conversion, but 107 * cyc2ns_scale needs to be a 32-bit value so that 32-bit multiplication 108 * (64-bit result) can be used. 109 * 110 * We can use khz divisor instead of mhz to keep a better precision. 111 * (mathieu.desnoyers@polymtl.ca) 112 * 113 * -johnstul@us.ibm.com "math is hard, lets go shopping!" 114 */ 115 116 static __always_inline unsigned long long cycles_2_ns(unsigned long long cyc) 117 { 118 struct cyc2ns_data data; 119 unsigned long long ns; 120 121 cyc2ns_read_begin(&data); 122 123 ns = data.cyc2ns_offset; 124 ns += mul_u64_u32_shr(cyc, data.cyc2ns_mul, data.cyc2ns_shift); 125 126 cyc2ns_read_end(); 127 128 return ns; 129 } 130 131 static void __set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long tsc_now) 132 { 133 unsigned long long ns_now; 134 struct cyc2ns_data data; 135 struct cyc2ns *c2n; 136 137 ns_now = cycles_2_ns(tsc_now); 138 139 /* 140 * Compute a new multiplier as per the above comment and ensure our 141 * time function is continuous; see the comment near struct 142 * cyc2ns_data. 143 */ 144 clocks_calc_mult_shift(&data.cyc2ns_mul, &data.cyc2ns_shift, khz, 145 NSEC_PER_MSEC, 0); 146 147 /* 148 * cyc2ns_shift is exported via arch_perf_update_userpage() where it is 149 * not expected to be greater than 31 due to the original published 150 * conversion algorithm shifting a 32-bit value (now specifies a 64-bit 151 * value) - refer perf_event_mmap_page documentation in perf_event.h. 152 */ 153 if (data.cyc2ns_shift == 32) { 154 data.cyc2ns_shift = 31; 155 data.cyc2ns_mul >>= 1; 156 } 157 158 data.cyc2ns_offset = ns_now - 159 mul_u64_u32_shr(tsc_now, data.cyc2ns_mul, data.cyc2ns_shift); 160 161 c2n = per_cpu_ptr(&cyc2ns, cpu); 162 163 raw_write_seqcount_latch(&c2n->seq); 164 c2n->data[0] = data; 165 raw_write_seqcount_latch(&c2n->seq); 166 c2n->data[1] = data; 167 } 168 169 static void set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long tsc_now) 170 { 171 unsigned long flags; 172 173 local_irq_save(flags); 174 sched_clock_idle_sleep_event(); 175 176 if (khz) 177 __set_cyc2ns_scale(khz, cpu, tsc_now); 178 179 sched_clock_idle_wakeup_event(); 180 local_irq_restore(flags); 181 } 182 183 /* 184 * Initialize cyc2ns for boot cpu 185 */ 186 static void __init cyc2ns_init_boot_cpu(void) 187 { 188 struct cyc2ns *c2n = this_cpu_ptr(&cyc2ns); 189 190 seqcount_latch_init(&c2n->seq); 191 __set_cyc2ns_scale(tsc_khz, smp_processor_id(), rdtsc()); 192 } 193 194 /* 195 * Secondary CPUs do not run through tsc_init(), so set up 196 * all the scale factors for all CPUs, assuming the same 197 * speed as the bootup CPU. 198 */ 199 static void __init cyc2ns_init_secondary_cpus(void) 200 { 201 unsigned int cpu, this_cpu = smp_processor_id(); 202 struct cyc2ns *c2n = this_cpu_ptr(&cyc2ns); 203 struct cyc2ns_data *data = c2n->data; 204 205 for_each_possible_cpu(cpu) { 206 if (cpu != this_cpu) { 207 seqcount_latch_init(&c2n->seq); 208 c2n = per_cpu_ptr(&cyc2ns, cpu); 209 c2n->data[0] = data[0]; 210 c2n->data[1] = data[1]; 211 } 212 } 213 } 214 215 /* 216 * Scheduler clock - returns current time in nanosec units. 217 */ 218 u64 native_sched_clock(void) 219 { 220 if (static_branch_likely(&__use_tsc)) { 221 u64 tsc_now = rdtsc(); 222 223 /* return the value in ns */ 224 return cycles_2_ns(tsc_now); 225 } 226 227 /* 228 * Fall back to jiffies if there's no TSC available: 229 * ( But note that we still use it if the TSC is marked 230 * unstable. We do this because unlike Time Of Day, 231 * the scheduler clock tolerates small errors and it's 232 * very important for it to be as fast as the platform 233 * can achieve it. ) 234 */ 235 236 /* No locking but a rare wrong value is not a big deal: */ 237 return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); 238 } 239 240 /* 241 * Generate a sched_clock if you already have a TSC value. 242 */ 243 u64 native_sched_clock_from_tsc(u64 tsc) 244 { 245 return cycles_2_ns(tsc); 246 } 247 248 /* We need to define a real function for sched_clock, to override the 249 weak default version */ 250 #ifdef CONFIG_PARAVIRT 251 unsigned long long sched_clock(void) 252 { 253 return paravirt_sched_clock(); 254 } 255 256 bool using_native_sched_clock(void) 257 { 258 return static_call_query(pv_sched_clock) == native_sched_clock; 259 } 260 #else 261 unsigned long long 262 sched_clock(void) __attribute__((alias("native_sched_clock"))); 263 264 bool using_native_sched_clock(void) { return true; } 265 #endif 266 267 int check_tsc_unstable(void) 268 { 269 return tsc_unstable; 270 } 271 EXPORT_SYMBOL_GPL(check_tsc_unstable); 272 273 #ifdef CONFIG_X86_TSC 274 int __init notsc_setup(char *str) 275 { 276 mark_tsc_unstable("boot parameter notsc"); 277 return 1; 278 } 279 #else 280 /* 281 * disable flag for tsc. Takes effect by clearing the TSC cpu flag 282 * in cpu/common.c 283 */ 284 int __init notsc_setup(char *str) 285 { 286 setup_clear_cpu_cap(X86_FEATURE_TSC); 287 return 1; 288 } 289 #endif 290 291 __setup("notsc", notsc_setup); 292 293 static int no_sched_irq_time; 294 static int no_tsc_watchdog; 295 296 static int __init tsc_setup(char *str) 297 { 298 if (!strcmp(str, "reliable")) 299 tsc_clocksource_reliable = 1; 300 if (!strncmp(str, "noirqtime", 9)) 301 no_sched_irq_time = 1; 302 if (!strcmp(str, "unstable")) 303 mark_tsc_unstable("boot parameter"); 304 if (!strcmp(str, "nowatchdog")) 305 no_tsc_watchdog = 1; 306 return 1; 307 } 308 309 __setup("tsc=", tsc_setup); 310 311 #define MAX_RETRIES 5 312 #define TSC_DEFAULT_THRESHOLD 0x20000 313 314 /* 315 * Read TSC and the reference counters. Take care of any disturbances 316 */ 317 static u64 tsc_read_refs(u64 *p, int hpet) 318 { 319 u64 t1, t2; 320 u64 thresh = tsc_khz ? tsc_khz >> 5 : TSC_DEFAULT_THRESHOLD; 321 int i; 322 323 for (i = 0; i < MAX_RETRIES; i++) { 324 t1 = get_cycles(); 325 if (hpet) 326 *p = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF; 327 else 328 *p = acpi_pm_read_early(); 329 t2 = get_cycles(); 330 if ((t2 - t1) < thresh) 331 return t2; 332 } 333 return ULLONG_MAX; 334 } 335 336 /* 337 * Calculate the TSC frequency from HPET reference 338 */ 339 static unsigned long calc_hpet_ref(u64 deltatsc, u64 hpet1, u64 hpet2) 340 { 341 u64 tmp; 342 343 if (hpet2 < hpet1) 344 hpet2 += 0x100000000ULL; 345 hpet2 -= hpet1; 346 tmp = ((u64)hpet2 * hpet_readl(HPET_PERIOD)); 347 do_div(tmp, 1000000); 348 deltatsc = div64_u64(deltatsc, tmp); 349 350 return (unsigned long) deltatsc; 351 } 352 353 /* 354 * Calculate the TSC frequency from PMTimer reference 355 */ 356 static unsigned long calc_pmtimer_ref(u64 deltatsc, u64 pm1, u64 pm2) 357 { 358 u64 tmp; 359 360 if (!pm1 && !pm2) 361 return ULONG_MAX; 362 363 if (pm2 < pm1) 364 pm2 += (u64)ACPI_PM_OVRRUN; 365 pm2 -= pm1; 366 tmp = pm2 * 1000000000LL; 367 do_div(tmp, PMTMR_TICKS_PER_SEC); 368 do_div(deltatsc, tmp); 369 370 return (unsigned long) deltatsc; 371 } 372 373 #define CAL_MS 10 374 #define CAL_LATCH (PIT_TICK_RATE / (1000 / CAL_MS)) 375 #define CAL_PIT_LOOPS 1000 376 377 #define CAL2_MS 50 378 #define CAL2_LATCH (PIT_TICK_RATE / (1000 / CAL2_MS)) 379 #define CAL2_PIT_LOOPS 5000 380 381 382 /* 383 * Try to calibrate the TSC against the Programmable 384 * Interrupt Timer and return the frequency of the TSC 385 * in kHz. 386 * 387 * Return ULONG_MAX on failure to calibrate. 388 */ 389 static unsigned long pit_calibrate_tsc(u32 latch, unsigned long ms, int loopmin) 390 { 391 u64 tsc, t1, t2, delta; 392 unsigned long tscmin, tscmax; 393 int pitcnt; 394 395 if (!has_legacy_pic()) { 396 /* 397 * Relies on tsc_early_delay_calibrate() to have given us semi 398 * usable udelay(), wait for the same 50ms we would have with 399 * the PIT loop below. 400 */ 401 udelay(10 * USEC_PER_MSEC); 402 udelay(10 * USEC_PER_MSEC); 403 udelay(10 * USEC_PER_MSEC); 404 udelay(10 * USEC_PER_MSEC); 405 udelay(10 * USEC_PER_MSEC); 406 return ULONG_MAX; 407 } 408 409 /* Set the Gate high, disable speaker */ 410 outb((inb(0x61) & ~0x02) | 0x01, 0x61); 411 412 /* 413 * Setup CTC channel 2* for mode 0, (interrupt on terminal 414 * count mode), binary count. Set the latch register to 50ms 415 * (LSB then MSB) to begin countdown. 416 */ 417 outb(0xb0, 0x43); 418 outb(latch & 0xff, 0x42); 419 outb(latch >> 8, 0x42); 420 421 tsc = t1 = t2 = get_cycles(); 422 423 pitcnt = 0; 424 tscmax = 0; 425 tscmin = ULONG_MAX; 426 while ((inb(0x61) & 0x20) == 0) { 427 t2 = get_cycles(); 428 delta = t2 - tsc; 429 tsc = t2; 430 if ((unsigned long) delta < tscmin) 431 tscmin = (unsigned int) delta; 432 if ((unsigned long) delta > tscmax) 433 tscmax = (unsigned int) delta; 434 pitcnt++; 435 } 436 437 /* 438 * Sanity checks: 439 * 440 * If we were not able to read the PIT more than loopmin 441 * times, then we have been hit by a massive SMI 442 * 443 * If the maximum is 10 times larger than the minimum, 444 * then we got hit by an SMI as well. 445 */ 446 if (pitcnt < loopmin || tscmax > 10 * tscmin) 447 return ULONG_MAX; 448 449 /* Calculate the PIT value */ 450 delta = t2 - t1; 451 do_div(delta, ms); 452 return delta; 453 } 454 455 /* 456 * This reads the current MSB of the PIT counter, and 457 * checks if we are running on sufficiently fast and 458 * non-virtualized hardware. 459 * 460 * Our expectations are: 461 * 462 * - the PIT is running at roughly 1.19MHz 463 * 464 * - each IO is going to take about 1us on real hardware, 465 * but we allow it to be much faster (by a factor of 10) or 466 * _slightly_ slower (ie we allow up to a 2us read+counter 467 * update - anything else implies a unacceptably slow CPU 468 * or PIT for the fast calibration to work. 469 * 470 * - with 256 PIT ticks to read the value, we have 214us to 471 * see the same MSB (and overhead like doing a single TSC 472 * read per MSB value etc). 473 * 474 * - We're doing 2 reads per loop (LSB, MSB), and we expect 475 * them each to take about a microsecond on real hardware. 476 * So we expect a count value of around 100. But we'll be 477 * generous, and accept anything over 50. 478 * 479 * - if the PIT is stuck, and we see *many* more reads, we 480 * return early (and the next caller of pit_expect_msb() 481 * then consider it a failure when they don't see the 482 * next expected value). 483 * 484 * These expectations mean that we know that we have seen the 485 * transition from one expected value to another with a fairly 486 * high accuracy, and we didn't miss any events. We can thus 487 * use the TSC value at the transitions to calculate a pretty 488 * good value for the TSC frequency. 489 */ 490 static inline int pit_verify_msb(unsigned char val) 491 { 492 /* Ignore LSB */ 493 inb(0x42); 494 return inb(0x42) == val; 495 } 496 497 static inline int pit_expect_msb(unsigned char val, u64 *tscp, unsigned long *deltap) 498 { 499 int count; 500 u64 tsc = 0, prev_tsc = 0; 501 502 for (count = 0; count < 50000; count++) { 503 if (!pit_verify_msb(val)) 504 break; 505 prev_tsc = tsc; 506 tsc = get_cycles(); 507 } 508 *deltap = get_cycles() - prev_tsc; 509 *tscp = tsc; 510 511 /* 512 * We require _some_ success, but the quality control 513 * will be based on the error terms on the TSC values. 514 */ 515 return count > 5; 516 } 517 518 /* 519 * How many MSB values do we want to see? We aim for 520 * a maximum error rate of 500ppm (in practice the 521 * real error is much smaller), but refuse to spend 522 * more than 50ms on it. 523 */ 524 #define MAX_QUICK_PIT_MS 50 525 #define MAX_QUICK_PIT_ITERATIONS (MAX_QUICK_PIT_MS * PIT_TICK_RATE / 1000 / 256) 526 527 static unsigned long quick_pit_calibrate(void) 528 { 529 int i; 530 u64 tsc, delta; 531 unsigned long d1, d2; 532 533 if (!has_legacy_pic()) 534 return 0; 535 536 /* Set the Gate high, disable speaker */ 537 outb((inb(0x61) & ~0x02) | 0x01, 0x61); 538 539 /* 540 * Counter 2, mode 0 (one-shot), binary count 541 * 542 * NOTE! Mode 2 decrements by two (and then the 543 * output is flipped each time, giving the same 544 * final output frequency as a decrement-by-one), 545 * so mode 0 is much better when looking at the 546 * individual counts. 547 */ 548 outb(0xb0, 0x43); 549 550 /* Start at 0xffff */ 551 outb(0xff, 0x42); 552 outb(0xff, 0x42); 553 554 /* 555 * The PIT starts counting at the next edge, so we 556 * need to delay for a microsecond. The easiest way 557 * to do that is to just read back the 16-bit counter 558 * once from the PIT. 559 */ 560 pit_verify_msb(0); 561 562 if (pit_expect_msb(0xff, &tsc, &d1)) { 563 for (i = 1; i <= MAX_QUICK_PIT_ITERATIONS; i++) { 564 if (!pit_expect_msb(0xff-i, &delta, &d2)) 565 break; 566 567 delta -= tsc; 568 569 /* 570 * Extrapolate the error and fail fast if the error will 571 * never be below 500 ppm. 572 */ 573 if (i == 1 && 574 d1 + d2 >= (delta * MAX_QUICK_PIT_ITERATIONS) >> 11) 575 return 0; 576 577 /* 578 * Iterate until the error is less than 500 ppm 579 */ 580 if (d1+d2 >= delta >> 11) 581 continue; 582 583 /* 584 * Check the PIT one more time to verify that 585 * all TSC reads were stable wrt the PIT. 586 * 587 * This also guarantees serialization of the 588 * last cycle read ('d2') in pit_expect_msb. 589 */ 590 if (!pit_verify_msb(0xfe - i)) 591 break; 592 goto success; 593 } 594 } 595 pr_info("Fast TSC calibration failed\n"); 596 return 0; 597 598 success: 599 /* 600 * Ok, if we get here, then we've seen the 601 * MSB of the PIT decrement 'i' times, and the 602 * error has shrunk to less than 500 ppm. 603 * 604 * As a result, we can depend on there not being 605 * any odd delays anywhere, and the TSC reads are 606 * reliable (within the error). 607 * 608 * kHz = ticks / time-in-seconds / 1000; 609 * kHz = (t2 - t1) / (I * 256 / PIT_TICK_RATE) / 1000 610 * kHz = ((t2 - t1) * PIT_TICK_RATE) / (I * 256 * 1000) 611 */ 612 delta *= PIT_TICK_RATE; 613 do_div(delta, i*256*1000); 614 pr_info("Fast TSC calibration using PIT\n"); 615 return delta; 616 } 617 618 /** 619 * native_calibrate_tsc 620 * Determine TSC frequency via CPUID, else return 0. 621 */ 622 unsigned long native_calibrate_tsc(void) 623 { 624 unsigned int eax_denominator, ebx_numerator, ecx_hz, edx; 625 unsigned int crystal_khz; 626 627 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) 628 return 0; 629 630 if (boot_cpu_data.cpuid_level < 0x15) 631 return 0; 632 633 eax_denominator = ebx_numerator = ecx_hz = edx = 0; 634 635 /* CPUID 15H TSC/Crystal ratio, plus optionally Crystal Hz */ 636 cpuid(0x15, &eax_denominator, &ebx_numerator, &ecx_hz, &edx); 637 638 if (ebx_numerator == 0 || eax_denominator == 0) 639 return 0; 640 641 crystal_khz = ecx_hz / 1000; 642 643 /* 644 * Denverton SoCs don't report crystal clock, and also don't support 645 * CPUID.0x16 for the calculation below, so hardcode the 25MHz crystal 646 * clock. 647 */ 648 if (crystal_khz == 0 && 649 boot_cpu_data.x86_model == INTEL_FAM6_ATOM_GOLDMONT_D) 650 crystal_khz = 25000; 651 652 /* 653 * TSC frequency reported directly by CPUID is a "hardware reported" 654 * frequency and is the most accurate one so far we have. This 655 * is considered a known frequency. 656 */ 657 if (crystal_khz != 0) 658 setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); 659 660 /* 661 * Some Intel SoCs like Skylake and Kabylake don't report the crystal 662 * clock, but we can easily calculate it to a high degree of accuracy 663 * by considering the crystal ratio and the CPU speed. 664 */ 665 if (crystal_khz == 0 && boot_cpu_data.cpuid_level >= 0x16) { 666 unsigned int eax_base_mhz, ebx, ecx, edx; 667 668 cpuid(0x16, &eax_base_mhz, &ebx, &ecx, &edx); 669 crystal_khz = eax_base_mhz * 1000 * 670 eax_denominator / ebx_numerator; 671 } 672 673 if (crystal_khz == 0) 674 return 0; 675 676 /* 677 * For Atom SoCs TSC is the only reliable clocksource. 678 * Mark TSC reliable so no watchdog on it. 679 */ 680 if (boot_cpu_data.x86_model == INTEL_FAM6_ATOM_GOLDMONT) 681 setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); 682 683 #ifdef CONFIG_X86_LOCAL_APIC 684 /* 685 * The local APIC appears to be fed by the core crystal clock 686 * (which sounds entirely sensible). We can set the global 687 * lapic_timer_period here to avoid having to calibrate the APIC 688 * timer later. 689 */ 690 lapic_timer_period = crystal_khz * 1000 / HZ; 691 #endif 692 693 return crystal_khz * ebx_numerator / eax_denominator; 694 } 695 696 static unsigned long cpu_khz_from_cpuid(void) 697 { 698 unsigned int eax_base_mhz, ebx_max_mhz, ecx_bus_mhz, edx; 699 700 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) 701 return 0; 702 703 if (boot_cpu_data.cpuid_level < 0x16) 704 return 0; 705 706 eax_base_mhz = ebx_max_mhz = ecx_bus_mhz = edx = 0; 707 708 cpuid(0x16, &eax_base_mhz, &ebx_max_mhz, &ecx_bus_mhz, &edx); 709 710 return eax_base_mhz * 1000; 711 } 712 713 /* 714 * calibrate cpu using pit, hpet, and ptimer methods. They are available 715 * later in boot after acpi is initialized. 716 */ 717 static unsigned long pit_hpet_ptimer_calibrate_cpu(void) 718 { 719 u64 tsc1, tsc2, delta, ref1, ref2; 720 unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX; 721 unsigned long flags, latch, ms; 722 int hpet = is_hpet_enabled(), i, loopmin; 723 724 /* 725 * Run 5 calibration loops to get the lowest frequency value 726 * (the best estimate). We use two different calibration modes 727 * here: 728 * 729 * 1) PIT loop. We set the PIT Channel 2 to oneshot mode and 730 * load a timeout of 50ms. We read the time right after we 731 * started the timer and wait until the PIT count down reaches 732 * zero. In each wait loop iteration we read the TSC and check 733 * the delta to the previous read. We keep track of the min 734 * and max values of that delta. The delta is mostly defined 735 * by the IO time of the PIT access, so we can detect when 736 * any disturbance happened between the two reads. If the 737 * maximum time is significantly larger than the minimum time, 738 * then we discard the result and have another try. 739 * 740 * 2) Reference counter. If available we use the HPET or the 741 * PMTIMER as a reference to check the sanity of that value. 742 * We use separate TSC readouts and check inside of the 743 * reference read for any possible disturbance. We discard 744 * disturbed values here as well. We do that around the PIT 745 * calibration delay loop as we have to wait for a certain 746 * amount of time anyway. 747 */ 748 749 /* Preset PIT loop values */ 750 latch = CAL_LATCH; 751 ms = CAL_MS; 752 loopmin = CAL_PIT_LOOPS; 753 754 for (i = 0; i < 3; i++) { 755 unsigned long tsc_pit_khz; 756 757 /* 758 * Read the start value and the reference count of 759 * hpet/pmtimer when available. Then do the PIT 760 * calibration, which will take at least 50ms, and 761 * read the end value. 762 */ 763 local_irq_save(flags); 764 tsc1 = tsc_read_refs(&ref1, hpet); 765 tsc_pit_khz = pit_calibrate_tsc(latch, ms, loopmin); 766 tsc2 = tsc_read_refs(&ref2, hpet); 767 local_irq_restore(flags); 768 769 /* Pick the lowest PIT TSC calibration so far */ 770 tsc_pit_min = min(tsc_pit_min, tsc_pit_khz); 771 772 /* hpet or pmtimer available ? */ 773 if (ref1 == ref2) 774 continue; 775 776 /* Check, whether the sampling was disturbed */ 777 if (tsc1 == ULLONG_MAX || tsc2 == ULLONG_MAX) 778 continue; 779 780 tsc2 = (tsc2 - tsc1) * 1000000LL; 781 if (hpet) 782 tsc2 = calc_hpet_ref(tsc2, ref1, ref2); 783 else 784 tsc2 = calc_pmtimer_ref(tsc2, ref1, ref2); 785 786 tsc_ref_min = min(tsc_ref_min, (unsigned long) tsc2); 787 788 /* Check the reference deviation */ 789 delta = ((u64) tsc_pit_min) * 100; 790 do_div(delta, tsc_ref_min); 791 792 /* 793 * If both calibration results are inside a 10% window 794 * then we can be sure, that the calibration 795 * succeeded. We break out of the loop right away. We 796 * use the reference value, as it is more precise. 797 */ 798 if (delta >= 90 && delta <= 110) { 799 pr_info("PIT calibration matches %s. %d loops\n", 800 hpet ? "HPET" : "PMTIMER", i + 1); 801 return tsc_ref_min; 802 } 803 804 /* 805 * Check whether PIT failed more than once. This 806 * happens in virtualized environments. We need to 807 * give the virtual PC a slightly longer timeframe for 808 * the HPET/PMTIMER to make the result precise. 809 */ 810 if (i == 1 && tsc_pit_min == ULONG_MAX) { 811 latch = CAL2_LATCH; 812 ms = CAL2_MS; 813 loopmin = CAL2_PIT_LOOPS; 814 } 815 } 816 817 /* 818 * Now check the results. 819 */ 820 if (tsc_pit_min == ULONG_MAX) { 821 /* PIT gave no useful value */ 822 pr_warn("Unable to calibrate against PIT\n"); 823 824 /* We don't have an alternative source, disable TSC */ 825 if (!hpet && !ref1 && !ref2) { 826 pr_notice("No reference (HPET/PMTIMER) available\n"); 827 return 0; 828 } 829 830 /* The alternative source failed as well, disable TSC */ 831 if (tsc_ref_min == ULONG_MAX) { 832 pr_warn("HPET/PMTIMER calibration failed\n"); 833 return 0; 834 } 835 836 /* Use the alternative source */ 837 pr_info("using %s reference calibration\n", 838 hpet ? "HPET" : "PMTIMER"); 839 840 return tsc_ref_min; 841 } 842 843 /* We don't have an alternative source, use the PIT calibration value */ 844 if (!hpet && !ref1 && !ref2) { 845 pr_info("Using PIT calibration value\n"); 846 return tsc_pit_min; 847 } 848 849 /* The alternative source failed, use the PIT calibration value */ 850 if (tsc_ref_min == ULONG_MAX) { 851 pr_warn("HPET/PMTIMER calibration failed. Using PIT calibration.\n"); 852 return tsc_pit_min; 853 } 854 855 /* 856 * The calibration values differ too much. In doubt, we use 857 * the PIT value as we know that there are PMTIMERs around 858 * running at double speed. At least we let the user know: 859 */ 860 pr_warn("PIT calibration deviates from %s: %lu %lu\n", 861 hpet ? "HPET" : "PMTIMER", tsc_pit_min, tsc_ref_min); 862 pr_info("Using PIT calibration value\n"); 863 return tsc_pit_min; 864 } 865 866 /** 867 * native_calibrate_cpu_early - can calibrate the cpu early in boot 868 */ 869 unsigned long native_calibrate_cpu_early(void) 870 { 871 unsigned long flags, fast_calibrate = cpu_khz_from_cpuid(); 872 873 if (!fast_calibrate) 874 fast_calibrate = cpu_khz_from_msr(); 875 if (!fast_calibrate) { 876 local_irq_save(flags); 877 fast_calibrate = quick_pit_calibrate(); 878 local_irq_restore(flags); 879 } 880 return fast_calibrate; 881 } 882 883 884 /** 885 * native_calibrate_cpu - calibrate the cpu 886 */ 887 static unsigned long native_calibrate_cpu(void) 888 { 889 unsigned long tsc_freq = native_calibrate_cpu_early(); 890 891 if (!tsc_freq) 892 tsc_freq = pit_hpet_ptimer_calibrate_cpu(); 893 894 return tsc_freq; 895 } 896 897 void recalibrate_cpu_khz(void) 898 { 899 #ifndef CONFIG_SMP 900 unsigned long cpu_khz_old = cpu_khz; 901 902 if (!boot_cpu_has(X86_FEATURE_TSC)) 903 return; 904 905 cpu_khz = x86_platform.calibrate_cpu(); 906 tsc_khz = x86_platform.calibrate_tsc(); 907 if (tsc_khz == 0) 908 tsc_khz = cpu_khz; 909 else if (abs(cpu_khz - tsc_khz) * 10 > tsc_khz) 910 cpu_khz = tsc_khz; 911 cpu_data(0).loops_per_jiffy = cpufreq_scale(cpu_data(0).loops_per_jiffy, 912 cpu_khz_old, cpu_khz); 913 #endif 914 } 915 916 EXPORT_SYMBOL(recalibrate_cpu_khz); 917 918 919 static unsigned long long cyc2ns_suspend; 920 921 void tsc_save_sched_clock_state(void) 922 { 923 if (!sched_clock_stable()) 924 return; 925 926 cyc2ns_suspend = sched_clock(); 927 } 928 929 /* 930 * Even on processors with invariant TSC, TSC gets reset in some the 931 * ACPI system sleep states. And in some systems BIOS seem to reinit TSC to 932 * arbitrary value (still sync'd across cpu's) during resume from such sleep 933 * states. To cope up with this, recompute the cyc2ns_offset for each cpu so 934 * that sched_clock() continues from the point where it was left off during 935 * suspend. 936 */ 937 void tsc_restore_sched_clock_state(void) 938 { 939 unsigned long long offset; 940 unsigned long flags; 941 int cpu; 942 943 if (!sched_clock_stable()) 944 return; 945 946 local_irq_save(flags); 947 948 /* 949 * We're coming out of suspend, there's no concurrency yet; don't 950 * bother being nice about the RCU stuff, just write to both 951 * data fields. 952 */ 953 954 this_cpu_write(cyc2ns.data[0].cyc2ns_offset, 0); 955 this_cpu_write(cyc2ns.data[1].cyc2ns_offset, 0); 956 957 offset = cyc2ns_suspend - sched_clock(); 958 959 for_each_possible_cpu(cpu) { 960 per_cpu(cyc2ns.data[0].cyc2ns_offset, cpu) = offset; 961 per_cpu(cyc2ns.data[1].cyc2ns_offset, cpu) = offset; 962 } 963 964 local_irq_restore(flags); 965 } 966 967 #ifdef CONFIG_CPU_FREQ 968 /* 969 * Frequency scaling support. Adjust the TSC based timer when the CPU frequency 970 * changes. 971 * 972 * NOTE: On SMP the situation is not fixable in general, so simply mark the TSC 973 * as unstable and give up in those cases. 974 * 975 * Should fix up last_tsc too. Currently gettimeofday in the 976 * first tick after the change will be slightly wrong. 977 */ 978 979 static unsigned int ref_freq; 980 static unsigned long loops_per_jiffy_ref; 981 static unsigned long tsc_khz_ref; 982 983 static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 984 void *data) 985 { 986 struct cpufreq_freqs *freq = data; 987 988 if (num_online_cpus() > 1) { 989 mark_tsc_unstable("cpufreq changes on SMP"); 990 return 0; 991 } 992 993 if (!ref_freq) { 994 ref_freq = freq->old; 995 loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy; 996 tsc_khz_ref = tsc_khz; 997 } 998 999 if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || 1000 (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { 1001 boot_cpu_data.loops_per_jiffy = 1002 cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); 1003 1004 tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); 1005 if (!(freq->flags & CPUFREQ_CONST_LOOPS)) 1006 mark_tsc_unstable("cpufreq changes"); 1007 1008 set_cyc2ns_scale(tsc_khz, freq->policy->cpu, rdtsc()); 1009 } 1010 1011 return 0; 1012 } 1013 1014 static struct notifier_block time_cpufreq_notifier_block = { 1015 .notifier_call = time_cpufreq_notifier 1016 }; 1017 1018 static int __init cpufreq_register_tsc_scaling(void) 1019 { 1020 if (!boot_cpu_has(X86_FEATURE_TSC)) 1021 return 0; 1022 if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) 1023 return 0; 1024 cpufreq_register_notifier(&time_cpufreq_notifier_block, 1025 CPUFREQ_TRANSITION_NOTIFIER); 1026 return 0; 1027 } 1028 1029 core_initcall(cpufreq_register_tsc_scaling); 1030 1031 #endif /* CONFIG_CPU_FREQ */ 1032 1033 #define ART_CPUID_LEAF (0x15) 1034 #define ART_MIN_DENOMINATOR (1) 1035 1036 1037 /* 1038 * If ART is present detect the numerator:denominator to convert to TSC 1039 */ 1040 static void __init detect_art(void) 1041 { 1042 unsigned int unused[2]; 1043 1044 if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF) 1045 return; 1046 1047 /* 1048 * Don't enable ART in a VM, non-stop TSC and TSC_ADJUST required, 1049 * and the TSC counter resets must not occur asynchronously. 1050 */ 1051 if (boot_cpu_has(X86_FEATURE_HYPERVISOR) || 1052 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC) || 1053 !boot_cpu_has(X86_FEATURE_TSC_ADJUST) || 1054 tsc_async_resets) 1055 return; 1056 1057 cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, 1058 &art_to_tsc_numerator, unused, unused+1); 1059 1060 if (art_to_tsc_denominator < ART_MIN_DENOMINATOR) 1061 return; 1062 1063 rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset); 1064 1065 /* Make this sticky over multiple CPU init calls */ 1066 setup_force_cpu_cap(X86_FEATURE_ART); 1067 } 1068 1069 1070 /* clocksource code */ 1071 1072 static void tsc_resume(struct clocksource *cs) 1073 { 1074 tsc_verify_tsc_adjust(true); 1075 } 1076 1077 /* 1078 * We used to compare the TSC to the cycle_last value in the clocksource 1079 * structure to avoid a nasty time-warp. This can be observed in a 1080 * very small window right after one CPU updated cycle_last under 1081 * xtime/vsyscall_gtod lock and the other CPU reads a TSC value which 1082 * is smaller than the cycle_last reference value due to a TSC which 1083 * is slightly behind. This delta is nowhere else observable, but in 1084 * that case it results in a forward time jump in the range of hours 1085 * due to the unsigned delta calculation of the time keeping core 1086 * code, which is necessary to support wrapping clocksources like pm 1087 * timer. 1088 * 1089 * This sanity check is now done in the core timekeeping code. 1090 * checking the result of read_tsc() - cycle_last for being negative. 1091 * That works because CLOCKSOURCE_MASK(64) does not mask out any bit. 1092 */ 1093 static u64 read_tsc(struct clocksource *cs) 1094 { 1095 return (u64)rdtsc_ordered(); 1096 } 1097 1098 static void tsc_cs_mark_unstable(struct clocksource *cs) 1099 { 1100 if (tsc_unstable) 1101 return; 1102 1103 tsc_unstable = 1; 1104 if (using_native_sched_clock()) 1105 clear_sched_clock_stable(); 1106 disable_sched_clock_irqtime(); 1107 pr_info("Marking TSC unstable due to clocksource watchdog\n"); 1108 } 1109 1110 static void tsc_cs_tick_stable(struct clocksource *cs) 1111 { 1112 if (tsc_unstable) 1113 return; 1114 1115 if (using_native_sched_clock()) 1116 sched_clock_tick_stable(); 1117 } 1118 1119 static int tsc_cs_enable(struct clocksource *cs) 1120 { 1121 vclocks_set_used(VDSO_CLOCKMODE_TSC); 1122 return 0; 1123 } 1124 1125 /* 1126 * .mask MUST be CLOCKSOURCE_MASK(64). See comment above read_tsc() 1127 */ 1128 static struct clocksource clocksource_tsc_early = { 1129 .name = "tsc-early", 1130 .rating = 299, 1131 .read = read_tsc, 1132 .mask = CLOCKSOURCE_MASK(64), 1133 .flags = CLOCK_SOURCE_IS_CONTINUOUS | 1134 CLOCK_SOURCE_MUST_VERIFY, 1135 .vdso_clock_mode = VDSO_CLOCKMODE_TSC, 1136 .enable = tsc_cs_enable, 1137 .resume = tsc_resume, 1138 .mark_unstable = tsc_cs_mark_unstable, 1139 .tick_stable = tsc_cs_tick_stable, 1140 .list = LIST_HEAD_INIT(clocksource_tsc_early.list), 1141 }; 1142 1143 /* 1144 * Must mark VALID_FOR_HRES early such that when we unregister tsc_early 1145 * this one will immediately take over. We will only register if TSC has 1146 * been found good. 1147 */ 1148 static struct clocksource clocksource_tsc = { 1149 .name = "tsc", 1150 .rating = 300, 1151 .read = read_tsc, 1152 .mask = CLOCKSOURCE_MASK(64), 1153 .flags = CLOCK_SOURCE_IS_CONTINUOUS | 1154 CLOCK_SOURCE_VALID_FOR_HRES | 1155 CLOCK_SOURCE_MUST_VERIFY, 1156 .vdso_clock_mode = VDSO_CLOCKMODE_TSC, 1157 .enable = tsc_cs_enable, 1158 .resume = tsc_resume, 1159 .mark_unstable = tsc_cs_mark_unstable, 1160 .tick_stable = tsc_cs_tick_stable, 1161 .list = LIST_HEAD_INIT(clocksource_tsc.list), 1162 }; 1163 1164 void mark_tsc_unstable(char *reason) 1165 { 1166 if (tsc_unstable) 1167 return; 1168 1169 tsc_unstable = 1; 1170 if (using_native_sched_clock()) 1171 clear_sched_clock_stable(); 1172 disable_sched_clock_irqtime(); 1173 pr_info("Marking TSC unstable due to %s\n", reason); 1174 1175 clocksource_mark_unstable(&clocksource_tsc_early); 1176 clocksource_mark_unstable(&clocksource_tsc); 1177 } 1178 1179 EXPORT_SYMBOL_GPL(mark_tsc_unstable); 1180 1181 static void __init check_system_tsc_reliable(void) 1182 { 1183 #if defined(CONFIG_MGEODEGX1) || defined(CONFIG_MGEODE_LX) || defined(CONFIG_X86_GENERIC) 1184 if (is_geode_lx()) { 1185 /* RTSC counts during suspend */ 1186 #define RTSC_SUSP 0x100 1187 unsigned long res_low, res_high; 1188 1189 rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); 1190 /* Geode_LX - the OLPC CPU has a very reliable TSC */ 1191 if (res_low & RTSC_SUSP) 1192 tsc_clocksource_reliable = 1; 1193 } 1194 #endif 1195 if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) 1196 tsc_clocksource_reliable = 1; 1197 } 1198 1199 /* 1200 * Make an educated guess if the TSC is trustworthy and synchronized 1201 * over all CPUs. 1202 */ 1203 int unsynchronized_tsc(void) 1204 { 1205 if (!boot_cpu_has(X86_FEATURE_TSC) || tsc_unstable) 1206 return 1; 1207 1208 #ifdef CONFIG_SMP 1209 if (apic_is_clustered_box()) 1210 return 1; 1211 #endif 1212 1213 if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) 1214 return 0; 1215 1216 if (tsc_clocksource_reliable) 1217 return 0; 1218 /* 1219 * Intel systems are normally all synchronized. 1220 * Exceptions must mark TSC as unstable: 1221 */ 1222 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { 1223 /* assume multi socket systems are not synchronized: */ 1224 if (num_possible_cpus() > 1) 1225 return 1; 1226 } 1227 1228 return 0; 1229 } 1230 1231 /* 1232 * Convert ART to TSC given numerator/denominator found in detect_art() 1233 */ 1234 struct system_counterval_t convert_art_to_tsc(u64 art) 1235 { 1236 u64 tmp, res, rem; 1237 1238 rem = do_div(art, art_to_tsc_denominator); 1239 1240 res = art * art_to_tsc_numerator; 1241 tmp = rem * art_to_tsc_numerator; 1242 1243 do_div(tmp, art_to_tsc_denominator); 1244 res += tmp + art_to_tsc_offset; 1245 1246 return (struct system_counterval_t) {.cs = art_related_clocksource, 1247 .cycles = res}; 1248 } 1249 EXPORT_SYMBOL(convert_art_to_tsc); 1250 1251 /** 1252 * convert_art_ns_to_tsc() - Convert ART in nanoseconds to TSC. 1253 * @art_ns: ART (Always Running Timer) in unit of nanoseconds 1254 * 1255 * PTM requires all timestamps to be in units of nanoseconds. When user 1256 * software requests a cross-timestamp, this function converts system timestamp 1257 * to TSC. 1258 * 1259 * This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set 1260 * indicating the tsc_khz is derived from CPUID[15H]. Drivers should check 1261 * that this flag is set before conversion to TSC is attempted. 1262 * 1263 * Return: 1264 * struct system_counterval_t - system counter value with the pointer to the 1265 * corresponding clocksource 1266 * @cycles: System counter value 1267 * @cs: Clocksource corresponding to system counter value. Used 1268 * by timekeeping code to verify comparability of two cycle 1269 * values. 1270 */ 1271 1272 struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns) 1273 { 1274 u64 tmp, res, rem; 1275 1276 rem = do_div(art_ns, USEC_PER_SEC); 1277 1278 res = art_ns * tsc_khz; 1279 tmp = rem * tsc_khz; 1280 1281 do_div(tmp, USEC_PER_SEC); 1282 res += tmp; 1283 1284 return (struct system_counterval_t) { .cs = art_related_clocksource, 1285 .cycles = res}; 1286 } 1287 EXPORT_SYMBOL(convert_art_ns_to_tsc); 1288 1289 1290 static void tsc_refine_calibration_work(struct work_struct *work); 1291 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work); 1292 /** 1293 * tsc_refine_calibration_work - Further refine tsc freq calibration 1294 * @work - ignored. 1295 * 1296 * This functions uses delayed work over a period of a 1297 * second to further refine the TSC freq value. Since this is 1298 * timer based, instead of loop based, we don't block the boot 1299 * process while this longer calibration is done. 1300 * 1301 * If there are any calibration anomalies (too many SMIs, etc), 1302 * or the refined calibration is off by 1% of the fast early 1303 * calibration, we throw out the new calibration and use the 1304 * early calibration. 1305 */ 1306 static void tsc_refine_calibration_work(struct work_struct *work) 1307 { 1308 static u64 tsc_start = ULLONG_MAX, ref_start; 1309 static int hpet; 1310 u64 tsc_stop, ref_stop, delta; 1311 unsigned long freq; 1312 int cpu; 1313 1314 /* Don't bother refining TSC on unstable systems */ 1315 if (tsc_unstable) 1316 goto unreg; 1317 1318 /* 1319 * Since the work is started early in boot, we may be 1320 * delayed the first time we expire. So set the workqueue 1321 * again once we know timers are working. 1322 */ 1323 if (tsc_start == ULLONG_MAX) { 1324 restart: 1325 /* 1326 * Only set hpet once, to avoid mixing hardware 1327 * if the hpet becomes enabled later. 1328 */ 1329 hpet = is_hpet_enabled(); 1330 tsc_start = tsc_read_refs(&ref_start, hpet); 1331 schedule_delayed_work(&tsc_irqwork, HZ); 1332 return; 1333 } 1334 1335 tsc_stop = tsc_read_refs(&ref_stop, hpet); 1336 1337 /* hpet or pmtimer available ? */ 1338 if (ref_start == ref_stop) 1339 goto out; 1340 1341 /* Check, whether the sampling was disturbed */ 1342 if (tsc_stop == ULLONG_MAX) 1343 goto restart; 1344 1345 delta = tsc_stop - tsc_start; 1346 delta *= 1000000LL; 1347 if (hpet) 1348 freq = calc_hpet_ref(delta, ref_start, ref_stop); 1349 else 1350 freq = calc_pmtimer_ref(delta, ref_start, ref_stop); 1351 1352 /* Make sure we're within 1% */ 1353 if (abs(tsc_khz - freq) > tsc_khz/100) 1354 goto out; 1355 1356 tsc_khz = freq; 1357 pr_info("Refined TSC clocksource calibration: %lu.%03lu MHz\n", 1358 (unsigned long)tsc_khz / 1000, 1359 (unsigned long)tsc_khz % 1000); 1360 1361 /* Inform the TSC deadline clockevent devices about the recalibration */ 1362 lapic_update_tsc_freq(); 1363 1364 /* Update the sched_clock() rate to match the clocksource one */ 1365 for_each_possible_cpu(cpu) 1366 set_cyc2ns_scale(tsc_khz, cpu, tsc_stop); 1367 1368 out: 1369 if (tsc_unstable) 1370 goto unreg; 1371 1372 if (boot_cpu_has(X86_FEATURE_ART)) 1373 art_related_clocksource = &clocksource_tsc; 1374 clocksource_register_khz(&clocksource_tsc, tsc_khz); 1375 unreg: 1376 clocksource_unregister(&clocksource_tsc_early); 1377 } 1378 1379 1380 static int __init init_tsc_clocksource(void) 1381 { 1382 if (!boot_cpu_has(X86_FEATURE_TSC) || !tsc_khz) 1383 return 0; 1384 1385 if (tsc_unstable) 1386 goto unreg; 1387 1388 if (tsc_clocksource_reliable || no_tsc_watchdog) 1389 clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; 1390 1391 if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3)) 1392 clocksource_tsc.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP; 1393 1394 /* 1395 * When TSC frequency is known (retrieved via MSR or CPUID), we skip 1396 * the refined calibration and directly register it as a clocksource. 1397 */ 1398 if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) { 1399 if (boot_cpu_has(X86_FEATURE_ART)) 1400 art_related_clocksource = &clocksource_tsc; 1401 clocksource_register_khz(&clocksource_tsc, tsc_khz); 1402 unreg: 1403 clocksource_unregister(&clocksource_tsc_early); 1404 return 0; 1405 } 1406 1407 schedule_delayed_work(&tsc_irqwork, 0); 1408 return 0; 1409 } 1410 /* 1411 * We use device_initcall here, to ensure we run after the hpet 1412 * is fully initialized, which may occur at fs_initcall time. 1413 */ 1414 device_initcall(init_tsc_clocksource); 1415 1416 static bool __init determine_cpu_tsc_frequencies(bool early) 1417 { 1418 /* Make sure that cpu and tsc are not already calibrated */ 1419 WARN_ON(cpu_khz || tsc_khz); 1420 1421 if (early) { 1422 cpu_khz = x86_platform.calibrate_cpu(); 1423 if (tsc_early_khz) 1424 tsc_khz = tsc_early_khz; 1425 else 1426 tsc_khz = x86_platform.calibrate_tsc(); 1427 } else { 1428 /* We should not be here with non-native cpu calibration */ 1429 WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu); 1430 cpu_khz = pit_hpet_ptimer_calibrate_cpu(); 1431 } 1432 1433 /* 1434 * Trust non-zero tsc_khz as authoritative, 1435 * and use it to sanity check cpu_khz, 1436 * which will be off if system timer is off. 1437 */ 1438 if (tsc_khz == 0) 1439 tsc_khz = cpu_khz; 1440 else if (abs(cpu_khz - tsc_khz) * 10 > tsc_khz) 1441 cpu_khz = tsc_khz; 1442 1443 if (tsc_khz == 0) 1444 return false; 1445 1446 pr_info("Detected %lu.%03lu MHz processor\n", 1447 (unsigned long)cpu_khz / KHZ, 1448 (unsigned long)cpu_khz % KHZ); 1449 1450 if (cpu_khz != tsc_khz) { 1451 pr_info("Detected %lu.%03lu MHz TSC", 1452 (unsigned long)tsc_khz / KHZ, 1453 (unsigned long)tsc_khz % KHZ); 1454 } 1455 return true; 1456 } 1457 1458 static unsigned long __init get_loops_per_jiffy(void) 1459 { 1460 u64 lpj = (u64)tsc_khz * KHZ; 1461 1462 do_div(lpj, HZ); 1463 return lpj; 1464 } 1465 1466 static void __init tsc_enable_sched_clock(void) 1467 { 1468 /* Sanitize TSC ADJUST before cyc2ns gets initialized */ 1469 tsc_store_and_check_tsc_adjust(true); 1470 cyc2ns_init_boot_cpu(); 1471 static_branch_enable(&__use_tsc); 1472 } 1473 1474 void __init tsc_early_init(void) 1475 { 1476 if (!boot_cpu_has(X86_FEATURE_TSC)) 1477 return; 1478 /* Don't change UV TSC multi-chassis synchronization */ 1479 if (is_early_uv_system()) 1480 return; 1481 if (!determine_cpu_tsc_frequencies(true)) 1482 return; 1483 loops_per_jiffy = get_loops_per_jiffy(); 1484 1485 tsc_enable_sched_clock(); 1486 } 1487 1488 void __init tsc_init(void) 1489 { 1490 /* 1491 * native_calibrate_cpu_early can only calibrate using methods that are 1492 * available early in boot. 1493 */ 1494 if (x86_platform.calibrate_cpu == native_calibrate_cpu_early) 1495 x86_platform.calibrate_cpu = native_calibrate_cpu; 1496 1497 if (!boot_cpu_has(X86_FEATURE_TSC)) { 1498 setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER); 1499 return; 1500 } 1501 1502 if (!tsc_khz) { 1503 /* We failed to determine frequencies earlier, try again */ 1504 if (!determine_cpu_tsc_frequencies(false)) { 1505 mark_tsc_unstable("could not calculate TSC khz"); 1506 setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER); 1507 return; 1508 } 1509 tsc_enable_sched_clock(); 1510 } 1511 1512 cyc2ns_init_secondary_cpus(); 1513 1514 if (!no_sched_irq_time) 1515 enable_sched_clock_irqtime(); 1516 1517 lpj_fine = get_loops_per_jiffy(); 1518 use_tsc_delay(); 1519 1520 check_system_tsc_reliable(); 1521 1522 if (unsynchronized_tsc()) { 1523 mark_tsc_unstable("TSCs unsynchronized"); 1524 return; 1525 } 1526 1527 if (tsc_clocksource_reliable || no_tsc_watchdog) 1528 clocksource_tsc_early.flags &= ~CLOCK_SOURCE_MUST_VERIFY; 1529 1530 clocksource_register_khz(&clocksource_tsc_early, tsc_khz); 1531 detect_art(); 1532 } 1533 1534 #ifdef CONFIG_SMP 1535 /* 1536 * If we have a constant TSC and are using the TSC for the delay loop, 1537 * we can skip clock calibration if another cpu in the same socket has already 1538 * been calibrated. This assumes that CONSTANT_TSC applies to all 1539 * cpus in the socket - this should be a safe assumption. 1540 */ 1541 unsigned long calibrate_delay_is_known(void) 1542 { 1543 int sibling, cpu = smp_processor_id(); 1544 int constant_tsc = cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC); 1545 const struct cpumask *mask = topology_core_cpumask(cpu); 1546 1547 if (!constant_tsc || !mask) 1548 return 0; 1549 1550 sibling = cpumask_any_but(mask, cpu); 1551 if (sibling < nr_cpu_ids) 1552 return cpu_data(sibling).loops_per_jiffy; 1553 return 0; 1554 } 1555 #endif 1556