Commit | Line | Data |
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bfc0f594 | 1 | #include <linux/kernel.h> |
0ef95533 AK |
2 | #include <linux/sched.h> |
3 | #include <linux/init.h> | |
4 | #include <linux/module.h> | |
5 | #include <linux/timer.h> | |
bfc0f594 | 6 | #include <linux/acpi_pmtmr.h> |
2dbe06fa | 7 | #include <linux/cpufreq.h> |
8fbbc4b4 AK |
8 | #include <linux/dmi.h> |
9 | #include <linux/delay.h> | |
10 | #include <linux/clocksource.h> | |
11 | #include <linux/percpu.h> | |
bfc0f594 AK |
12 | |
13 | #include <asm/hpet.h> | |
8fbbc4b4 AK |
14 | #include <asm/timer.h> |
15 | #include <asm/vgtod.h> | |
16 | #include <asm/time.h> | |
17 | #include <asm/delay.h> | |
0ef95533 AK |
18 | |
19 | unsigned int cpu_khz; /* TSC clocks / usec, not used here */ | |
20 | EXPORT_SYMBOL(cpu_khz); | |
21 | unsigned int tsc_khz; | |
22 | EXPORT_SYMBOL(tsc_khz); | |
23 | ||
24 | /* | |
25 | * TSC can be unstable due to cpufreq or due to unsynced TSCs | |
26 | */ | |
8fbbc4b4 | 27 | static int tsc_unstable; |
0ef95533 AK |
28 | |
29 | /* native_sched_clock() is called before tsc_init(), so | |
30 | we must start with the TSC soft disabled to prevent | |
31 | erroneous rdtsc usage on !cpu_has_tsc processors */ | |
8fbbc4b4 | 32 | static int tsc_disabled = -1; |
0ef95533 AK |
33 | |
34 | /* | |
35 | * Scheduler clock - returns current time in nanosec units. | |
36 | */ | |
37 | u64 native_sched_clock(void) | |
38 | { | |
39 | u64 this_offset; | |
40 | ||
41 | /* | |
42 | * Fall back to jiffies if there's no TSC available: | |
43 | * ( But note that we still use it if the TSC is marked | |
44 | * unstable. We do this because unlike Time Of Day, | |
45 | * the scheduler clock tolerates small errors and it's | |
46 | * very important for it to be as fast as the platform | |
47 | * can achive it. ) | |
48 | */ | |
49 | if (unlikely(tsc_disabled)) { | |
50 | /* No locking but a rare wrong value is not a big deal: */ | |
51 | return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); | |
52 | } | |
53 | ||
54 | /* read the Time Stamp Counter: */ | |
55 | rdtscll(this_offset); | |
56 | ||
57 | /* return the value in ns */ | |
58 | return cycles_2_ns(this_offset); | |
59 | } | |
60 | ||
61 | /* We need to define a real function for sched_clock, to override the | |
62 | weak default version */ | |
63 | #ifdef CONFIG_PARAVIRT | |
64 | unsigned long long sched_clock(void) | |
65 | { | |
66 | return paravirt_sched_clock(); | |
67 | } | |
68 | #else | |
69 | unsigned long long | |
70 | sched_clock(void) __attribute__((alias("native_sched_clock"))); | |
71 | #endif | |
72 | ||
73 | int check_tsc_unstable(void) | |
74 | { | |
75 | return tsc_unstable; | |
76 | } | |
77 | EXPORT_SYMBOL_GPL(check_tsc_unstable); | |
78 | ||
79 | #ifdef CONFIG_X86_TSC | |
80 | int __init notsc_setup(char *str) | |
81 | { | |
82 | printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, " | |
83 | "cannot disable TSC completely.\n"); | |
84 | tsc_disabled = 1; | |
85 | return 1; | |
86 | } | |
87 | #else | |
88 | /* | |
89 | * disable flag for tsc. Takes effect by clearing the TSC cpu flag | |
90 | * in cpu/common.c | |
91 | */ | |
92 | int __init notsc_setup(char *str) | |
93 | { | |
94 | setup_clear_cpu_cap(X86_FEATURE_TSC); | |
95 | return 1; | |
96 | } | |
97 | #endif | |
98 | ||
99 | __setup("notsc", notsc_setup); | |
bfc0f594 AK |
100 | |
101 | #define MAX_RETRIES 5 | |
102 | #define SMI_TRESHOLD 50000 | |
103 | ||
104 | /* | |
105 | * Read TSC and the reference counters. Take care of SMI disturbance | |
106 | */ | |
827014be | 107 | static u64 tsc_read_refs(u64 *p, int hpet) |
bfc0f594 AK |
108 | { |
109 | u64 t1, t2; | |
110 | int i; | |
111 | ||
112 | for (i = 0; i < MAX_RETRIES; i++) { | |
113 | t1 = get_cycles(); | |
114 | if (hpet) | |
827014be | 115 | *p = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF; |
bfc0f594 | 116 | else |
827014be | 117 | *p = acpi_pm_read_early(); |
bfc0f594 AK |
118 | t2 = get_cycles(); |
119 | if ((t2 - t1) < SMI_TRESHOLD) | |
120 | return t2; | |
121 | } | |
122 | return ULLONG_MAX; | |
123 | } | |
124 | ||
d683ef7a TG |
125 | /* |
126 | * Calculate the TSC frequency from HPET reference | |
127 | */ | |
128 | static unsigned long calc_hpet_ref(u64 deltatsc, u64 hpet1, u64 hpet2) | |
129 | { | |
130 | u64 tmp; | |
131 | ||
132 | if (hpet2 < hpet1) | |
133 | hpet2 += 0x100000000ULL; | |
134 | hpet2 -= hpet1; | |
135 | tmp = ((u64)hpet2 * hpet_readl(HPET_PERIOD)); | |
136 | do_div(tmp, 1000000); | |
137 | do_div(deltatsc, tmp); | |
138 | ||
139 | return (unsigned long) deltatsc; | |
140 | } | |
141 | ||
142 | /* | |
143 | * Calculate the TSC frequency from PMTimer reference | |
144 | */ | |
145 | static unsigned long calc_pmtimer_ref(u64 deltatsc, u64 pm1, u64 pm2) | |
146 | { | |
147 | u64 tmp; | |
148 | ||
149 | if (!pm1 && !pm2) | |
150 | return ULONG_MAX; | |
151 | ||
152 | if (pm2 < pm1) | |
153 | pm2 += (u64)ACPI_PM_OVRRUN; | |
154 | pm2 -= pm1; | |
155 | tmp = pm2 * 1000000000LL; | |
156 | do_div(tmp, PMTMR_TICKS_PER_SEC); | |
157 | do_div(deltatsc, tmp); | |
158 | ||
159 | return (unsigned long) deltatsc; | |
160 | } | |
161 | ||
cce3e057 TG |
162 | #define CAL_MS 50 |
163 | #define CAL_LATCH (CLOCK_TICK_RATE / (1000 / CAL_MS)) | |
164 | #define CAL_PIT_LOOPS 5000 | |
165 | ||
ec0c15af LT |
166 | /* |
167 | * Try to calibrate the TSC against the Programmable | |
168 | * Interrupt Timer and return the frequency of the TSC | |
169 | * in kHz. | |
170 | * | |
171 | * Return ULONG_MAX on failure to calibrate. | |
172 | */ | |
173 | static unsigned long pit_calibrate_tsc(void) | |
174 | { | |
175 | u64 tsc, t1, t2, delta; | |
176 | unsigned long tscmin, tscmax; | |
177 | int pitcnt; | |
178 | ||
179 | /* Set the Gate high, disable speaker */ | |
180 | outb((inb(0x61) & ~0x02) | 0x01, 0x61); | |
181 | ||
182 | /* | |
183 | * Setup CTC channel 2* for mode 0, (interrupt on terminal | |
184 | * count mode), binary count. Set the latch register to 50ms | |
185 | * (LSB then MSB) to begin countdown. | |
186 | */ | |
187 | outb(0xb0, 0x43); | |
cce3e057 TG |
188 | outb(CAL_LATCH & 0xff, 0x42); |
189 | outb(CAL_LATCH >> 8, 0x42); | |
ec0c15af LT |
190 | |
191 | tsc = t1 = t2 = get_cycles(); | |
192 | ||
193 | pitcnt = 0; | |
194 | tscmax = 0; | |
195 | tscmin = ULONG_MAX; | |
196 | while ((inb(0x61) & 0x20) == 0) { | |
197 | t2 = get_cycles(); | |
198 | delta = t2 - tsc; | |
199 | tsc = t2; | |
200 | if ((unsigned long) delta < tscmin) | |
201 | tscmin = (unsigned int) delta; | |
202 | if ((unsigned long) delta > tscmax) | |
203 | tscmax = (unsigned int) delta; | |
204 | pitcnt++; | |
205 | } | |
206 | ||
207 | /* | |
208 | * Sanity checks: | |
209 | * | |
cce3e057 | 210 | * If we were not able to read the PIT more than PIT_MIN_LOOPS |
ec0c15af LT |
211 | * times, then we have been hit by a massive SMI |
212 | * | |
213 | * If the maximum is 10 times larger than the minimum, | |
214 | * then we got hit by an SMI as well. | |
215 | */ | |
cce3e057 | 216 | if (pitcnt < CAL_PIT_LOOPS || tscmax > 10 * tscmin) |
ec0c15af LT |
217 | return ULONG_MAX; |
218 | ||
219 | /* Calculate the PIT value */ | |
220 | delta = t2 - t1; | |
cce3e057 | 221 | do_div(delta, CAL_MS); |
ec0c15af LT |
222 | return delta; |
223 | } | |
224 | ||
225 | ||
bfc0f594 | 226 | /** |
e93ef949 | 227 | * native_calibrate_tsc - calibrate the tsc on boot |
bfc0f594 | 228 | */ |
e93ef949 | 229 | unsigned long native_calibrate_tsc(void) |
bfc0f594 | 230 | { |
827014be | 231 | u64 tsc1, tsc2, delta, ref1, ref2; |
fbb16e24 | 232 | unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX; |
ec0c15af LT |
233 | unsigned long flags; |
234 | int hpet = is_hpet_enabled(), i; | |
bfc0f594 | 235 | |
fbb16e24 TG |
236 | /* |
237 | * Run 5 calibration loops to get the lowest frequency value | |
238 | * (the best estimate). We use two different calibration modes | |
239 | * here: | |
240 | * | |
241 | * 1) PIT loop. We set the PIT Channel 2 to oneshot mode and | |
242 | * load a timeout of 50ms. We read the time right after we | |
243 | * started the timer and wait until the PIT count down reaches | |
244 | * zero. In each wait loop iteration we read the TSC and check | |
245 | * the delta to the previous read. We keep track of the min | |
246 | * and max values of that delta. The delta is mostly defined | |
247 | * by the IO time of the PIT access, so we can detect when a | |
248 | * SMI/SMM disturbance happend between the two reads. If the | |
249 | * maximum time is significantly larger than the minimum time, | |
250 | * then we discard the result and have another try. | |
251 | * | |
252 | * 2) Reference counter. If available we use the HPET or the | |
253 | * PMTIMER as a reference to check the sanity of that value. | |
254 | * We use separate TSC readouts and check inside of the | |
255 | * reference read for a SMI/SMM disturbance. We dicard | |
256 | * disturbed values here as well. We do that around the PIT | |
257 | * calibration delay loop as we have to wait for a certain | |
258 | * amount of time anyway. | |
259 | */ | |
260 | for (i = 0; i < 5; i++) { | |
ec0c15af | 261 | unsigned long tsc_pit_khz; |
fbb16e24 TG |
262 | |
263 | /* | |
264 | * Read the start value and the reference count of | |
ec0c15af LT |
265 | * hpet/pmtimer when available. Then do the PIT |
266 | * calibration, which will take at least 50ms, and | |
267 | * read the end value. | |
fbb16e24 | 268 | */ |
ec0c15af | 269 | local_irq_save(flags); |
827014be | 270 | tsc1 = tsc_read_refs(&ref1, hpet); |
ec0c15af | 271 | tsc_pit_khz = pit_calibrate_tsc(); |
827014be | 272 | tsc2 = tsc_read_refs(&ref2, hpet); |
fbb16e24 TG |
273 | local_irq_restore(flags); |
274 | ||
ec0c15af LT |
275 | /* Pick the lowest PIT TSC calibration so far */ |
276 | tsc_pit_min = min(tsc_pit_min, tsc_pit_khz); | |
fbb16e24 TG |
277 | |
278 | /* hpet or pmtimer available ? */ | |
827014be | 279 | if (!hpet && !ref1 && !ref2) |
fbb16e24 TG |
280 | continue; |
281 | ||
282 | /* Check, whether the sampling was disturbed by an SMI */ | |
283 | if (tsc1 == ULLONG_MAX || tsc2 == ULLONG_MAX) | |
284 | continue; | |
285 | ||
286 | tsc2 = (tsc2 - tsc1) * 1000000LL; | |
d683ef7a | 287 | if (hpet) |
827014be | 288 | tsc2 = calc_hpet_ref(tsc2, ref1, ref2); |
d683ef7a | 289 | else |
827014be | 290 | tsc2 = calc_pmtimer_ref(tsc2, ref1, ref2); |
fbb16e24 | 291 | |
fbb16e24 TG |
292 | tsc_ref_min = min(tsc_ref_min, (unsigned long) tsc2); |
293 | } | |
bfc0f594 AK |
294 | |
295 | /* | |
fbb16e24 | 296 | * Now check the results. |
bfc0f594 | 297 | */ |
fbb16e24 TG |
298 | if (tsc_pit_min == ULONG_MAX) { |
299 | /* PIT gave no useful value */ | |
300 | printk(KERN_WARNING "TSC: PIT calibration failed due to " | |
301 | "SMI disturbance.\n"); | |
302 | ||
303 | /* We don't have an alternative source, disable TSC */ | |
827014be | 304 | if (!hpet && !ref1 && !ref2) { |
fbb16e24 TG |
305 | printk("TSC: No reference (HPET/PMTIMER) available\n"); |
306 | return 0; | |
307 | } | |
308 | ||
309 | /* The alternative source failed as well, disable TSC */ | |
310 | if (tsc_ref_min == ULONG_MAX) { | |
311 | printk(KERN_WARNING "TSC: HPET/PMTIMER calibration " | |
312 | "failed due to SMI disturbance.\n"); | |
313 | return 0; | |
314 | } | |
315 | ||
316 | /* Use the alternative source */ | |
317 | printk(KERN_INFO "TSC: using %s reference calibration\n", | |
318 | hpet ? "HPET" : "PMTIMER"); | |
319 | ||
320 | return tsc_ref_min; | |
321 | } | |
bfc0f594 | 322 | |
fbb16e24 | 323 | /* We don't have an alternative source, use the PIT calibration value */ |
827014be | 324 | if (!hpet && !ref1 && !ref2) { |
fbb16e24 TG |
325 | printk(KERN_INFO "TSC: Using PIT calibration value\n"); |
326 | return tsc_pit_min; | |
bfc0f594 AK |
327 | } |
328 | ||
fbb16e24 TG |
329 | /* The alternative source failed, use the PIT calibration value */ |
330 | if (tsc_ref_min == ULONG_MAX) { | |
331 | printk(KERN_WARNING "TSC: HPET/PMTIMER calibration failed due " | |
332 | "to SMI disturbance. Using PIT calibration\n"); | |
333 | return tsc_pit_min; | |
bfc0f594 AK |
334 | } |
335 | ||
fbb16e24 TG |
336 | /* Check the reference deviation */ |
337 | delta = ((u64) tsc_pit_min) * 100; | |
338 | do_div(delta, tsc_ref_min); | |
339 | ||
340 | /* | |
341 | * If both calibration results are inside a 5% window, the we | |
342 | * use the lower frequency of those as it is probably the | |
343 | * closest estimate. | |
344 | */ | |
345 | if (delta >= 95 && delta <= 105) { | |
346 | printk(KERN_INFO "TSC: PIT calibration confirmed by %s.\n", | |
347 | hpet ? "HPET" : "PMTIMER"); | |
348 | printk(KERN_INFO "TSC: using %s calibration value\n", | |
349 | tsc_pit_min <= tsc_ref_min ? "PIT" : | |
350 | hpet ? "HPET" : "PMTIMER"); | |
351 | return tsc_pit_min <= tsc_ref_min ? tsc_pit_min : tsc_ref_min; | |
bfc0f594 AK |
352 | } |
353 | ||
fbb16e24 TG |
354 | printk(KERN_WARNING "TSC: PIT calibration deviates from %s: %lu %lu.\n", |
355 | hpet ? "HPET" : "PMTIMER", tsc_pit_min, tsc_ref_min); | |
bfc0f594 | 356 | |
fbb16e24 TG |
357 | /* |
358 | * The calibration values differ too much. In doubt, we use | |
359 | * the PIT value as we know that there are PMTIMERs around | |
360 | * running at double speed. | |
361 | */ | |
362 | printk(KERN_INFO "TSC: Using PIT calibration value\n"); | |
363 | return tsc_pit_min; | |
bfc0f594 AK |
364 | } |
365 | ||
bfc0f594 AK |
366 | #ifdef CONFIG_X86_32 |
367 | /* Only called from the Powernow K7 cpu freq driver */ | |
368 | int recalibrate_cpu_khz(void) | |
369 | { | |
370 | #ifndef CONFIG_SMP | |
371 | unsigned long cpu_khz_old = cpu_khz; | |
372 | ||
373 | if (cpu_has_tsc) { | |
e93ef949 AK |
374 | tsc_khz = calibrate_tsc(); |
375 | cpu_khz = tsc_khz; | |
bfc0f594 AK |
376 | cpu_data(0).loops_per_jiffy = |
377 | cpufreq_scale(cpu_data(0).loops_per_jiffy, | |
378 | cpu_khz_old, cpu_khz); | |
379 | return 0; | |
380 | } else | |
381 | return -ENODEV; | |
382 | #else | |
383 | return -ENODEV; | |
384 | #endif | |
385 | } | |
386 | ||
387 | EXPORT_SYMBOL(recalibrate_cpu_khz); | |
388 | ||
389 | #endif /* CONFIG_X86_32 */ | |
2dbe06fa AK |
390 | |
391 | /* Accelerators for sched_clock() | |
392 | * convert from cycles(64bits) => nanoseconds (64bits) | |
393 | * basic equation: | |
394 | * ns = cycles / (freq / ns_per_sec) | |
395 | * ns = cycles * (ns_per_sec / freq) | |
396 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) | |
397 | * ns = cycles * (10^6 / cpu_khz) | |
398 | * | |
399 | * Then we use scaling math (suggested by george@mvista.com) to get: | |
400 | * ns = cycles * (10^6 * SC / cpu_khz) / SC | |
401 | * ns = cycles * cyc2ns_scale / SC | |
402 | * | |
403 | * And since SC is a constant power of two, we can convert the div | |
404 | * into a shift. | |
405 | * | |
406 | * We can use khz divisor instead of mhz to keep a better precision, since | |
407 | * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. | |
408 | * (mathieu.desnoyers@polymtl.ca) | |
409 | * | |
410 | * -johnstul@us.ibm.com "math is hard, lets go shopping!" | |
411 | */ | |
412 | ||
413 | DEFINE_PER_CPU(unsigned long, cyc2ns); | |
414 | ||
8fbbc4b4 | 415 | static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) |
2dbe06fa AK |
416 | { |
417 | unsigned long long tsc_now, ns_now; | |
418 | unsigned long flags, *scale; | |
419 | ||
420 | local_irq_save(flags); | |
421 | sched_clock_idle_sleep_event(); | |
422 | ||
423 | scale = &per_cpu(cyc2ns, cpu); | |
424 | ||
425 | rdtscll(tsc_now); | |
426 | ns_now = __cycles_2_ns(tsc_now); | |
427 | ||
428 | if (cpu_khz) | |
429 | *scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz; | |
430 | ||
431 | sched_clock_idle_wakeup_event(0); | |
432 | local_irq_restore(flags); | |
433 | } | |
434 | ||
435 | #ifdef CONFIG_CPU_FREQ | |
436 | ||
437 | /* Frequency scaling support. Adjust the TSC based timer when the cpu frequency | |
438 | * changes. | |
439 | * | |
440 | * RED-PEN: On SMP we assume all CPUs run with the same frequency. It's | |
441 | * not that important because current Opteron setups do not support | |
442 | * scaling on SMP anyroads. | |
443 | * | |
444 | * Should fix up last_tsc too. Currently gettimeofday in the | |
445 | * first tick after the change will be slightly wrong. | |
446 | */ | |
447 | ||
448 | static unsigned int ref_freq; | |
449 | static unsigned long loops_per_jiffy_ref; | |
450 | static unsigned long tsc_khz_ref; | |
451 | ||
452 | static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, | |
453 | void *data) | |
454 | { | |
455 | struct cpufreq_freqs *freq = data; | |
456 | unsigned long *lpj, dummy; | |
457 | ||
458 | if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC)) | |
459 | return 0; | |
460 | ||
461 | lpj = &dummy; | |
462 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
463 | #ifdef CONFIG_SMP | |
464 | lpj = &cpu_data(freq->cpu).loops_per_jiffy; | |
465 | #else | |
466 | lpj = &boot_cpu_data.loops_per_jiffy; | |
467 | #endif | |
468 | ||
469 | if (!ref_freq) { | |
470 | ref_freq = freq->old; | |
471 | loops_per_jiffy_ref = *lpj; | |
472 | tsc_khz_ref = tsc_khz; | |
473 | } | |
474 | if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || | |
475 | (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) || | |
476 | (val == CPUFREQ_RESUMECHANGE)) { | |
477 | *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); | |
478 | ||
479 | tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); | |
480 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
481 | mark_tsc_unstable("cpufreq changes"); | |
482 | } | |
483 | ||
52a8968c | 484 | set_cyc2ns_scale(tsc_khz, freq->cpu); |
2dbe06fa AK |
485 | |
486 | return 0; | |
487 | } | |
488 | ||
489 | static struct notifier_block time_cpufreq_notifier_block = { | |
490 | .notifier_call = time_cpufreq_notifier | |
491 | }; | |
492 | ||
493 | static int __init cpufreq_tsc(void) | |
494 | { | |
060700b5 LT |
495 | if (!cpu_has_tsc) |
496 | return 0; | |
497 | if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) | |
498 | return 0; | |
2dbe06fa AK |
499 | cpufreq_register_notifier(&time_cpufreq_notifier_block, |
500 | CPUFREQ_TRANSITION_NOTIFIER); | |
501 | return 0; | |
502 | } | |
503 | ||
504 | core_initcall(cpufreq_tsc); | |
505 | ||
506 | #endif /* CONFIG_CPU_FREQ */ | |
8fbbc4b4 AK |
507 | |
508 | /* clocksource code */ | |
509 | ||
510 | static struct clocksource clocksource_tsc; | |
511 | ||
512 | /* | |
513 | * We compare the TSC to the cycle_last value in the clocksource | |
514 | * structure to avoid a nasty time-warp. This can be observed in a | |
515 | * very small window right after one CPU updated cycle_last under | |
516 | * xtime/vsyscall_gtod lock and the other CPU reads a TSC value which | |
517 | * is smaller than the cycle_last reference value due to a TSC which | |
518 | * is slighty behind. This delta is nowhere else observable, but in | |
519 | * that case it results in a forward time jump in the range of hours | |
520 | * due to the unsigned delta calculation of the time keeping core | |
521 | * code, which is necessary to support wrapping clocksources like pm | |
522 | * timer. | |
523 | */ | |
524 | static cycle_t read_tsc(void) | |
525 | { | |
526 | cycle_t ret = (cycle_t)get_cycles(); | |
527 | ||
528 | return ret >= clocksource_tsc.cycle_last ? | |
529 | ret : clocksource_tsc.cycle_last; | |
530 | } | |
531 | ||
431ceb83 | 532 | #ifdef CONFIG_X86_64 |
8fbbc4b4 AK |
533 | static cycle_t __vsyscall_fn vread_tsc(void) |
534 | { | |
535 | cycle_t ret = (cycle_t)vget_cycles(); | |
536 | ||
537 | return ret >= __vsyscall_gtod_data.clock.cycle_last ? | |
538 | ret : __vsyscall_gtod_data.clock.cycle_last; | |
539 | } | |
431ceb83 | 540 | #endif |
8fbbc4b4 AK |
541 | |
542 | static struct clocksource clocksource_tsc = { | |
543 | .name = "tsc", | |
544 | .rating = 300, | |
545 | .read = read_tsc, | |
546 | .mask = CLOCKSOURCE_MASK(64), | |
547 | .shift = 22, | |
548 | .flags = CLOCK_SOURCE_IS_CONTINUOUS | | |
549 | CLOCK_SOURCE_MUST_VERIFY, | |
550 | #ifdef CONFIG_X86_64 | |
551 | .vread = vread_tsc, | |
552 | #endif | |
553 | }; | |
554 | ||
555 | void mark_tsc_unstable(char *reason) | |
556 | { | |
557 | if (!tsc_unstable) { | |
558 | tsc_unstable = 1; | |
559 | printk("Marking TSC unstable due to %s\n", reason); | |
560 | /* Change only the rating, when not registered */ | |
561 | if (clocksource_tsc.mult) | |
562 | clocksource_change_rating(&clocksource_tsc, 0); | |
563 | else | |
564 | clocksource_tsc.rating = 0; | |
565 | } | |
566 | } | |
567 | ||
568 | EXPORT_SYMBOL_GPL(mark_tsc_unstable); | |
569 | ||
570 | static int __init dmi_mark_tsc_unstable(const struct dmi_system_id *d) | |
571 | { | |
572 | printk(KERN_NOTICE "%s detected: marking TSC unstable.\n", | |
573 | d->ident); | |
574 | tsc_unstable = 1; | |
575 | return 0; | |
576 | } | |
577 | ||
578 | /* List of systems that have known TSC problems */ | |
579 | static struct dmi_system_id __initdata bad_tsc_dmi_table[] = { | |
580 | { | |
581 | .callback = dmi_mark_tsc_unstable, | |
582 | .ident = "IBM Thinkpad 380XD", | |
583 | .matches = { | |
584 | DMI_MATCH(DMI_BOARD_VENDOR, "IBM"), | |
585 | DMI_MATCH(DMI_BOARD_NAME, "2635FA0"), | |
586 | }, | |
587 | }, | |
588 | {} | |
589 | }; | |
590 | ||
591 | /* | |
592 | * Geode_LX - the OLPC CPU has a possibly a very reliable TSC | |
593 | */ | |
594 | #ifdef CONFIG_MGEODE_LX | |
595 | /* RTSC counts during suspend */ | |
596 | #define RTSC_SUSP 0x100 | |
597 | ||
598 | static void __init check_geode_tsc_reliable(void) | |
599 | { | |
600 | unsigned long res_low, res_high; | |
601 | ||
602 | rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); | |
603 | if (res_low & RTSC_SUSP) | |
604 | clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; | |
605 | } | |
606 | #else | |
607 | static inline void check_geode_tsc_reliable(void) { } | |
608 | #endif | |
609 | ||
610 | /* | |
611 | * Make an educated guess if the TSC is trustworthy and synchronized | |
612 | * over all CPUs. | |
613 | */ | |
614 | __cpuinit int unsynchronized_tsc(void) | |
615 | { | |
616 | if (!cpu_has_tsc || tsc_unstable) | |
617 | return 1; | |
618 | ||
619 | #ifdef CONFIG_SMP | |
620 | if (apic_is_clustered_box()) | |
621 | return 1; | |
622 | #endif | |
623 | ||
624 | if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) | |
625 | return 0; | |
626 | /* | |
627 | * Intel systems are normally all synchronized. | |
628 | * Exceptions must mark TSC as unstable: | |
629 | */ | |
630 | if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { | |
631 | /* assume multi socket systems are not synchronized: */ | |
632 | if (num_possible_cpus() > 1) | |
633 | tsc_unstable = 1; | |
634 | } | |
635 | ||
636 | return tsc_unstable; | |
637 | } | |
638 | ||
639 | static void __init init_tsc_clocksource(void) | |
640 | { | |
641 | clocksource_tsc.mult = clocksource_khz2mult(tsc_khz, | |
642 | clocksource_tsc.shift); | |
643 | /* lower the rating if we already know its unstable: */ | |
644 | if (check_tsc_unstable()) { | |
645 | clocksource_tsc.rating = 0; | |
646 | clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS; | |
647 | } | |
648 | clocksource_register(&clocksource_tsc); | |
649 | } | |
650 | ||
651 | void __init tsc_init(void) | |
652 | { | |
653 | u64 lpj; | |
654 | int cpu; | |
655 | ||
656 | if (!cpu_has_tsc) | |
657 | return; | |
658 | ||
e93ef949 AK |
659 | tsc_khz = calibrate_tsc(); |
660 | cpu_khz = tsc_khz; | |
8fbbc4b4 | 661 | |
e93ef949 | 662 | if (!tsc_khz) { |
8fbbc4b4 AK |
663 | mark_tsc_unstable("could not calculate TSC khz"); |
664 | return; | |
665 | } | |
666 | ||
667 | #ifdef CONFIG_X86_64 | |
668 | if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) && | |
669 | (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)) | |
670 | cpu_khz = calibrate_cpu(); | |
671 | #endif | |
672 | ||
673 | lpj = ((u64)tsc_khz * 1000); | |
674 | do_div(lpj, HZ); | |
675 | lpj_fine = lpj; | |
676 | ||
677 | printk("Detected %lu.%03lu MHz processor.\n", | |
678 | (unsigned long)cpu_khz / 1000, | |
679 | (unsigned long)cpu_khz % 1000); | |
680 | ||
681 | /* | |
682 | * Secondary CPUs do not run through tsc_init(), so set up | |
683 | * all the scale factors for all CPUs, assuming the same | |
684 | * speed as the bootup CPU. (cpufreq notifiers will fix this | |
685 | * up if their speed diverges) | |
686 | */ | |
687 | for_each_possible_cpu(cpu) | |
688 | set_cyc2ns_scale(cpu_khz, cpu); | |
689 | ||
690 | if (tsc_disabled > 0) | |
691 | return; | |
692 | ||
693 | /* now allow native_sched_clock() to use rdtsc */ | |
694 | tsc_disabled = 0; | |
695 | ||
696 | use_tsc_delay(); | |
697 | /* Check and install the TSC clocksource */ | |
698 | dmi_check_system(bad_tsc_dmi_table); | |
699 | ||
700 | if (unsynchronized_tsc()) | |
701 | mark_tsc_unstable("TSCs unsynchronized"); | |
702 | ||
703 | check_geode_tsc_reliable(); | |
704 | init_tsc_clocksource(); | |
705 | } | |
706 |