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 | ||
a977c400 | 162 | #define CAL_MS 10 |
cce3e057 | 163 | #define CAL_LATCH (CLOCK_TICK_RATE / (1000 / CAL_MS)) |
a977c400 TG |
164 | #define CAL_PIT_LOOPS 1000 |
165 | ||
166 | #define CAL2_MS 50 | |
167 | #define CAL2_LATCH (CLOCK_TICK_RATE / (1000 / CAL2_MS)) | |
168 | #define CAL2_PIT_LOOPS 5000 | |
169 | ||
cce3e057 | 170 | |
ec0c15af LT |
171 | /* |
172 | * Try to calibrate the TSC against the Programmable | |
173 | * Interrupt Timer and return the frequency of the TSC | |
174 | * in kHz. | |
175 | * | |
176 | * Return ULONG_MAX on failure to calibrate. | |
177 | */ | |
a977c400 | 178 | static unsigned long pit_calibrate_tsc(u32 latch, unsigned long ms, int loopmin) |
ec0c15af LT |
179 | { |
180 | u64 tsc, t1, t2, delta; | |
181 | unsigned long tscmin, tscmax; | |
182 | int pitcnt; | |
183 | ||
184 | /* Set the Gate high, disable speaker */ | |
185 | outb((inb(0x61) & ~0x02) | 0x01, 0x61); | |
186 | ||
187 | /* | |
188 | * Setup CTC channel 2* for mode 0, (interrupt on terminal | |
189 | * count mode), binary count. Set the latch register to 50ms | |
190 | * (LSB then MSB) to begin countdown. | |
191 | */ | |
192 | outb(0xb0, 0x43); | |
a977c400 TG |
193 | outb(latch & 0xff, 0x42); |
194 | outb(latch >> 8, 0x42); | |
ec0c15af LT |
195 | |
196 | tsc = t1 = t2 = get_cycles(); | |
197 | ||
198 | pitcnt = 0; | |
199 | tscmax = 0; | |
200 | tscmin = ULONG_MAX; | |
201 | while ((inb(0x61) & 0x20) == 0) { | |
202 | t2 = get_cycles(); | |
203 | delta = t2 - tsc; | |
204 | tsc = t2; | |
205 | if ((unsigned long) delta < tscmin) | |
206 | tscmin = (unsigned int) delta; | |
207 | if ((unsigned long) delta > tscmax) | |
208 | tscmax = (unsigned int) delta; | |
209 | pitcnt++; | |
210 | } | |
211 | ||
212 | /* | |
213 | * Sanity checks: | |
214 | * | |
a977c400 | 215 | * If we were not able to read the PIT more than loopmin |
ec0c15af LT |
216 | * times, then we have been hit by a massive SMI |
217 | * | |
218 | * If the maximum is 10 times larger than the minimum, | |
219 | * then we got hit by an SMI as well. | |
220 | */ | |
a977c400 | 221 | if (pitcnt < loopmin || tscmax > 10 * tscmin) |
ec0c15af LT |
222 | return ULONG_MAX; |
223 | ||
224 | /* Calculate the PIT value */ | |
225 | delta = t2 - t1; | |
a977c400 | 226 | do_div(delta, ms); |
ec0c15af LT |
227 | return delta; |
228 | } | |
229 | ||
230 | ||
bfc0f594 | 231 | /** |
e93ef949 | 232 | * native_calibrate_tsc - calibrate the tsc on boot |
bfc0f594 | 233 | */ |
e93ef949 | 234 | unsigned long native_calibrate_tsc(void) |
bfc0f594 | 235 | { |
827014be | 236 | u64 tsc1, tsc2, delta, ref1, ref2; |
fbb16e24 | 237 | unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX; |
a977c400 TG |
238 | unsigned long flags, latch, ms; |
239 | int hpet = is_hpet_enabled(), i, loopmin; | |
bfc0f594 | 240 | |
fbb16e24 TG |
241 | /* |
242 | * Run 5 calibration loops to get the lowest frequency value | |
243 | * (the best estimate). We use two different calibration modes | |
244 | * here: | |
245 | * | |
246 | * 1) PIT loop. We set the PIT Channel 2 to oneshot mode and | |
247 | * load a timeout of 50ms. We read the time right after we | |
248 | * started the timer and wait until the PIT count down reaches | |
249 | * zero. In each wait loop iteration we read the TSC and check | |
250 | * the delta to the previous read. We keep track of the min | |
251 | * and max values of that delta. The delta is mostly defined | |
252 | * by the IO time of the PIT access, so we can detect when a | |
253 | * SMI/SMM disturbance happend between the two reads. If the | |
254 | * maximum time is significantly larger than the minimum time, | |
255 | * then we discard the result and have another try. | |
256 | * | |
257 | * 2) Reference counter. If available we use the HPET or the | |
258 | * PMTIMER as a reference to check the sanity of that value. | |
259 | * We use separate TSC readouts and check inside of the | |
260 | * reference read for a SMI/SMM disturbance. We dicard | |
261 | * disturbed values here as well. We do that around the PIT | |
262 | * calibration delay loop as we have to wait for a certain | |
263 | * amount of time anyway. | |
264 | */ | |
a977c400 TG |
265 | |
266 | /* Preset PIT loop values */ | |
267 | latch = CAL_LATCH; | |
268 | ms = CAL_MS; | |
269 | loopmin = CAL_PIT_LOOPS; | |
270 | ||
271 | for (i = 0; i < 3; i++) { | |
ec0c15af | 272 | unsigned long tsc_pit_khz; |
fbb16e24 TG |
273 | |
274 | /* | |
275 | * Read the start value and the reference count of | |
ec0c15af LT |
276 | * hpet/pmtimer when available. Then do the PIT |
277 | * calibration, which will take at least 50ms, and | |
278 | * read the end value. | |
fbb16e24 | 279 | */ |
ec0c15af | 280 | local_irq_save(flags); |
827014be | 281 | tsc1 = tsc_read_refs(&ref1, hpet); |
a977c400 | 282 | tsc_pit_khz = pit_calibrate_tsc(latch, ms, loopmin); |
827014be | 283 | tsc2 = tsc_read_refs(&ref2, hpet); |
fbb16e24 TG |
284 | local_irq_restore(flags); |
285 | ||
ec0c15af LT |
286 | /* Pick the lowest PIT TSC calibration so far */ |
287 | tsc_pit_min = min(tsc_pit_min, tsc_pit_khz); | |
fbb16e24 TG |
288 | |
289 | /* hpet or pmtimer available ? */ | |
827014be | 290 | if (!hpet && !ref1 && !ref2) |
fbb16e24 TG |
291 | continue; |
292 | ||
293 | /* Check, whether the sampling was disturbed by an SMI */ | |
294 | if (tsc1 == ULLONG_MAX || tsc2 == ULLONG_MAX) | |
295 | continue; | |
296 | ||
297 | tsc2 = (tsc2 - tsc1) * 1000000LL; | |
d683ef7a | 298 | if (hpet) |
827014be | 299 | tsc2 = calc_hpet_ref(tsc2, ref1, ref2); |
d683ef7a | 300 | else |
827014be | 301 | tsc2 = calc_pmtimer_ref(tsc2, ref1, ref2); |
fbb16e24 | 302 | |
fbb16e24 | 303 | tsc_ref_min = min(tsc_ref_min, (unsigned long) tsc2); |
a977c400 TG |
304 | |
305 | /* Check the reference deviation */ | |
306 | delta = ((u64) tsc_pit_min) * 100; | |
307 | do_div(delta, tsc_ref_min); | |
308 | ||
309 | /* | |
310 | * If both calibration results are inside a 10% window | |
311 | * then we can be sure, that the calibration | |
312 | * succeeded. We break out of the loop right away. We | |
313 | * use the reference value, as it is more precise. | |
314 | */ | |
315 | if (delta >= 90 && delta <= 110) { | |
316 | printk(KERN_INFO | |
317 | "TSC: PIT calibration matches %s. %d loops\n", | |
318 | hpet ? "HPET" : "PMTIMER", i + 1); | |
319 | return tsc_ref_min; | |
320 | } | |
321 | ||
322 | /* | |
323 | * Check whether PIT failed more than once. This | |
324 | * happens in virtualized environments. We need to | |
325 | * give the virtual PC a slightly longer timeframe for | |
326 | * the HPET/PMTIMER to make the result precise. | |
327 | */ | |
328 | if (i == 1 && tsc_pit_min == ULONG_MAX) { | |
329 | latch = CAL2_LATCH; | |
330 | ms = CAL2_MS; | |
331 | loopmin = CAL2_PIT_LOOPS; | |
332 | } | |
fbb16e24 | 333 | } |
bfc0f594 AK |
334 | |
335 | /* | |
fbb16e24 | 336 | * Now check the results. |
bfc0f594 | 337 | */ |
fbb16e24 TG |
338 | if (tsc_pit_min == ULONG_MAX) { |
339 | /* PIT gave no useful value */ | |
340 | printk(KERN_WARNING "TSC: PIT calibration failed due to " | |
341 | "SMI disturbance.\n"); | |
342 | ||
343 | /* We don't have an alternative source, disable TSC */ | |
827014be | 344 | if (!hpet && !ref1 && !ref2) { |
fbb16e24 TG |
345 | printk("TSC: No reference (HPET/PMTIMER) available\n"); |
346 | return 0; | |
347 | } | |
348 | ||
349 | /* The alternative source failed as well, disable TSC */ | |
350 | if (tsc_ref_min == ULONG_MAX) { | |
351 | printk(KERN_WARNING "TSC: HPET/PMTIMER calibration " | |
a977c400 | 352 | "failed.\n"); |
fbb16e24 TG |
353 | return 0; |
354 | } | |
355 | ||
356 | /* Use the alternative source */ | |
357 | printk(KERN_INFO "TSC: using %s reference calibration\n", | |
358 | hpet ? "HPET" : "PMTIMER"); | |
359 | ||
360 | return tsc_ref_min; | |
361 | } | |
bfc0f594 | 362 | |
fbb16e24 | 363 | /* We don't have an alternative source, use the PIT calibration value */ |
827014be | 364 | if (!hpet && !ref1 && !ref2) { |
fbb16e24 TG |
365 | printk(KERN_INFO "TSC: Using PIT calibration value\n"); |
366 | return tsc_pit_min; | |
bfc0f594 AK |
367 | } |
368 | ||
fbb16e24 TG |
369 | /* The alternative source failed, use the PIT calibration value */ |
370 | if (tsc_ref_min == ULONG_MAX) { | |
a977c400 TG |
371 | printk(KERN_WARNING "TSC: HPET/PMTIMER calibration failed. " |
372 | "Using PIT calibration\n"); | |
fbb16e24 | 373 | return tsc_pit_min; |
bfc0f594 AK |
374 | } |
375 | ||
fbb16e24 TG |
376 | /* |
377 | * The calibration values differ too much. In doubt, we use | |
378 | * the PIT value as we know that there are PMTIMERs around | |
a977c400 | 379 | * running at double speed. At least we let the user know: |
fbb16e24 | 380 | */ |
a977c400 TG |
381 | printk(KERN_WARNING "TSC: PIT calibration deviates from %s: %lu %lu.\n", |
382 | hpet ? "HPET" : "PMTIMER", tsc_pit_min, tsc_ref_min); | |
fbb16e24 TG |
383 | printk(KERN_INFO "TSC: Using PIT calibration value\n"); |
384 | return tsc_pit_min; | |
bfc0f594 AK |
385 | } |
386 | ||
bfc0f594 AK |
387 | #ifdef CONFIG_X86_32 |
388 | /* Only called from the Powernow K7 cpu freq driver */ | |
389 | int recalibrate_cpu_khz(void) | |
390 | { | |
391 | #ifndef CONFIG_SMP | |
392 | unsigned long cpu_khz_old = cpu_khz; | |
393 | ||
394 | if (cpu_has_tsc) { | |
e93ef949 AK |
395 | tsc_khz = calibrate_tsc(); |
396 | cpu_khz = tsc_khz; | |
bfc0f594 AK |
397 | cpu_data(0).loops_per_jiffy = |
398 | cpufreq_scale(cpu_data(0).loops_per_jiffy, | |
399 | cpu_khz_old, cpu_khz); | |
400 | return 0; | |
401 | } else | |
402 | return -ENODEV; | |
403 | #else | |
404 | return -ENODEV; | |
405 | #endif | |
406 | } | |
407 | ||
408 | EXPORT_SYMBOL(recalibrate_cpu_khz); | |
409 | ||
410 | #endif /* CONFIG_X86_32 */ | |
2dbe06fa AK |
411 | |
412 | /* Accelerators for sched_clock() | |
413 | * convert from cycles(64bits) => nanoseconds (64bits) | |
414 | * basic equation: | |
415 | * ns = cycles / (freq / ns_per_sec) | |
416 | * ns = cycles * (ns_per_sec / freq) | |
417 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) | |
418 | * ns = cycles * (10^6 / cpu_khz) | |
419 | * | |
420 | * Then we use scaling math (suggested by george@mvista.com) to get: | |
421 | * ns = cycles * (10^6 * SC / cpu_khz) / SC | |
422 | * ns = cycles * cyc2ns_scale / SC | |
423 | * | |
424 | * And since SC is a constant power of two, we can convert the div | |
425 | * into a shift. | |
426 | * | |
427 | * We can use khz divisor instead of mhz to keep a better precision, since | |
428 | * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. | |
429 | * (mathieu.desnoyers@polymtl.ca) | |
430 | * | |
431 | * -johnstul@us.ibm.com "math is hard, lets go shopping!" | |
432 | */ | |
433 | ||
434 | DEFINE_PER_CPU(unsigned long, cyc2ns); | |
435 | ||
8fbbc4b4 | 436 | static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) |
2dbe06fa AK |
437 | { |
438 | unsigned long long tsc_now, ns_now; | |
439 | unsigned long flags, *scale; | |
440 | ||
441 | local_irq_save(flags); | |
442 | sched_clock_idle_sleep_event(); | |
443 | ||
444 | scale = &per_cpu(cyc2ns, cpu); | |
445 | ||
446 | rdtscll(tsc_now); | |
447 | ns_now = __cycles_2_ns(tsc_now); | |
448 | ||
449 | if (cpu_khz) | |
450 | *scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz; | |
451 | ||
452 | sched_clock_idle_wakeup_event(0); | |
453 | local_irq_restore(flags); | |
454 | } | |
455 | ||
456 | #ifdef CONFIG_CPU_FREQ | |
457 | ||
458 | /* Frequency scaling support. Adjust the TSC based timer when the cpu frequency | |
459 | * changes. | |
460 | * | |
461 | * RED-PEN: On SMP we assume all CPUs run with the same frequency. It's | |
462 | * not that important because current Opteron setups do not support | |
463 | * scaling on SMP anyroads. | |
464 | * | |
465 | * Should fix up last_tsc too. Currently gettimeofday in the | |
466 | * first tick after the change will be slightly wrong. | |
467 | */ | |
468 | ||
469 | static unsigned int ref_freq; | |
470 | static unsigned long loops_per_jiffy_ref; | |
471 | static unsigned long tsc_khz_ref; | |
472 | ||
473 | static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, | |
474 | void *data) | |
475 | { | |
476 | struct cpufreq_freqs *freq = data; | |
477 | unsigned long *lpj, dummy; | |
478 | ||
479 | if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC)) | |
480 | return 0; | |
481 | ||
482 | lpj = &dummy; | |
483 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
484 | #ifdef CONFIG_SMP | |
485 | lpj = &cpu_data(freq->cpu).loops_per_jiffy; | |
486 | #else | |
487 | lpj = &boot_cpu_data.loops_per_jiffy; | |
488 | #endif | |
489 | ||
490 | if (!ref_freq) { | |
491 | ref_freq = freq->old; | |
492 | loops_per_jiffy_ref = *lpj; | |
493 | tsc_khz_ref = tsc_khz; | |
494 | } | |
495 | if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || | |
496 | (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) || | |
497 | (val == CPUFREQ_RESUMECHANGE)) { | |
498 | *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); | |
499 | ||
500 | tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); | |
501 | if (!(freq->flags & CPUFREQ_CONST_LOOPS)) | |
502 | mark_tsc_unstable("cpufreq changes"); | |
503 | } | |
504 | ||
52a8968c | 505 | set_cyc2ns_scale(tsc_khz, freq->cpu); |
2dbe06fa AK |
506 | |
507 | return 0; | |
508 | } | |
509 | ||
510 | static struct notifier_block time_cpufreq_notifier_block = { | |
511 | .notifier_call = time_cpufreq_notifier | |
512 | }; | |
513 | ||
514 | static int __init cpufreq_tsc(void) | |
515 | { | |
060700b5 LT |
516 | if (!cpu_has_tsc) |
517 | return 0; | |
518 | if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) | |
519 | return 0; | |
2dbe06fa AK |
520 | cpufreq_register_notifier(&time_cpufreq_notifier_block, |
521 | CPUFREQ_TRANSITION_NOTIFIER); | |
522 | return 0; | |
523 | } | |
524 | ||
525 | core_initcall(cpufreq_tsc); | |
526 | ||
527 | #endif /* CONFIG_CPU_FREQ */ | |
8fbbc4b4 AK |
528 | |
529 | /* clocksource code */ | |
530 | ||
531 | static struct clocksource clocksource_tsc; | |
532 | ||
533 | /* | |
534 | * We compare the TSC to the cycle_last value in the clocksource | |
535 | * structure to avoid a nasty time-warp. This can be observed in a | |
536 | * very small window right after one CPU updated cycle_last under | |
537 | * xtime/vsyscall_gtod lock and the other CPU reads a TSC value which | |
538 | * is smaller than the cycle_last reference value due to a TSC which | |
539 | * is slighty behind. This delta is nowhere else observable, but in | |
540 | * that case it results in a forward time jump in the range of hours | |
541 | * due to the unsigned delta calculation of the time keeping core | |
542 | * code, which is necessary to support wrapping clocksources like pm | |
543 | * timer. | |
544 | */ | |
545 | static cycle_t read_tsc(void) | |
546 | { | |
547 | cycle_t ret = (cycle_t)get_cycles(); | |
548 | ||
549 | return ret >= clocksource_tsc.cycle_last ? | |
550 | ret : clocksource_tsc.cycle_last; | |
551 | } | |
552 | ||
431ceb83 | 553 | #ifdef CONFIG_X86_64 |
8fbbc4b4 AK |
554 | static cycle_t __vsyscall_fn vread_tsc(void) |
555 | { | |
556 | cycle_t ret = (cycle_t)vget_cycles(); | |
557 | ||
558 | return ret >= __vsyscall_gtod_data.clock.cycle_last ? | |
559 | ret : __vsyscall_gtod_data.clock.cycle_last; | |
560 | } | |
431ceb83 | 561 | #endif |
8fbbc4b4 AK |
562 | |
563 | static struct clocksource clocksource_tsc = { | |
564 | .name = "tsc", | |
565 | .rating = 300, | |
566 | .read = read_tsc, | |
567 | .mask = CLOCKSOURCE_MASK(64), | |
568 | .shift = 22, | |
569 | .flags = CLOCK_SOURCE_IS_CONTINUOUS | | |
570 | CLOCK_SOURCE_MUST_VERIFY, | |
571 | #ifdef CONFIG_X86_64 | |
572 | .vread = vread_tsc, | |
573 | #endif | |
574 | }; | |
575 | ||
576 | void mark_tsc_unstable(char *reason) | |
577 | { | |
578 | if (!tsc_unstable) { | |
579 | tsc_unstable = 1; | |
580 | printk("Marking TSC unstable due to %s\n", reason); | |
581 | /* Change only the rating, when not registered */ | |
582 | if (clocksource_tsc.mult) | |
583 | clocksource_change_rating(&clocksource_tsc, 0); | |
584 | else | |
585 | clocksource_tsc.rating = 0; | |
586 | } | |
587 | } | |
588 | ||
589 | EXPORT_SYMBOL_GPL(mark_tsc_unstable); | |
590 | ||
591 | static int __init dmi_mark_tsc_unstable(const struct dmi_system_id *d) | |
592 | { | |
593 | printk(KERN_NOTICE "%s detected: marking TSC unstable.\n", | |
594 | d->ident); | |
595 | tsc_unstable = 1; | |
596 | return 0; | |
597 | } | |
598 | ||
599 | /* List of systems that have known TSC problems */ | |
600 | static struct dmi_system_id __initdata bad_tsc_dmi_table[] = { | |
601 | { | |
602 | .callback = dmi_mark_tsc_unstable, | |
603 | .ident = "IBM Thinkpad 380XD", | |
604 | .matches = { | |
605 | DMI_MATCH(DMI_BOARD_VENDOR, "IBM"), | |
606 | DMI_MATCH(DMI_BOARD_NAME, "2635FA0"), | |
607 | }, | |
608 | }, | |
609 | {} | |
610 | }; | |
611 | ||
612 | /* | |
613 | * Geode_LX - the OLPC CPU has a possibly a very reliable TSC | |
614 | */ | |
615 | #ifdef CONFIG_MGEODE_LX | |
616 | /* RTSC counts during suspend */ | |
617 | #define RTSC_SUSP 0x100 | |
618 | ||
619 | static void __init check_geode_tsc_reliable(void) | |
620 | { | |
621 | unsigned long res_low, res_high; | |
622 | ||
623 | rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); | |
624 | if (res_low & RTSC_SUSP) | |
625 | clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY; | |
626 | } | |
627 | #else | |
628 | static inline void check_geode_tsc_reliable(void) { } | |
629 | #endif | |
630 | ||
631 | /* | |
632 | * Make an educated guess if the TSC is trustworthy and synchronized | |
633 | * over all CPUs. | |
634 | */ | |
635 | __cpuinit int unsynchronized_tsc(void) | |
636 | { | |
637 | if (!cpu_has_tsc || tsc_unstable) | |
638 | return 1; | |
639 | ||
640 | #ifdef CONFIG_SMP | |
641 | if (apic_is_clustered_box()) | |
642 | return 1; | |
643 | #endif | |
644 | ||
645 | if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) | |
646 | return 0; | |
647 | /* | |
648 | * Intel systems are normally all synchronized. | |
649 | * Exceptions must mark TSC as unstable: | |
650 | */ | |
651 | if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { | |
652 | /* assume multi socket systems are not synchronized: */ | |
653 | if (num_possible_cpus() > 1) | |
654 | tsc_unstable = 1; | |
655 | } | |
656 | ||
657 | return tsc_unstable; | |
658 | } | |
659 | ||
660 | static void __init init_tsc_clocksource(void) | |
661 | { | |
662 | clocksource_tsc.mult = clocksource_khz2mult(tsc_khz, | |
663 | clocksource_tsc.shift); | |
664 | /* lower the rating if we already know its unstable: */ | |
665 | if (check_tsc_unstable()) { | |
666 | clocksource_tsc.rating = 0; | |
667 | clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS; | |
668 | } | |
669 | clocksource_register(&clocksource_tsc); | |
670 | } | |
671 | ||
672 | void __init tsc_init(void) | |
673 | { | |
674 | u64 lpj; | |
675 | int cpu; | |
676 | ||
677 | if (!cpu_has_tsc) | |
678 | return; | |
679 | ||
e93ef949 AK |
680 | tsc_khz = calibrate_tsc(); |
681 | cpu_khz = tsc_khz; | |
8fbbc4b4 | 682 | |
e93ef949 | 683 | if (!tsc_khz) { |
8fbbc4b4 AK |
684 | mark_tsc_unstable("could not calculate TSC khz"); |
685 | return; | |
686 | } | |
687 | ||
688 | #ifdef CONFIG_X86_64 | |
689 | if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) && | |
690 | (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)) | |
691 | cpu_khz = calibrate_cpu(); | |
692 | #endif | |
693 | ||
694 | lpj = ((u64)tsc_khz * 1000); | |
695 | do_div(lpj, HZ); | |
696 | lpj_fine = lpj; | |
697 | ||
698 | printk("Detected %lu.%03lu MHz processor.\n", | |
699 | (unsigned long)cpu_khz / 1000, | |
700 | (unsigned long)cpu_khz % 1000); | |
701 | ||
702 | /* | |
703 | * Secondary CPUs do not run through tsc_init(), so set up | |
704 | * all the scale factors for all CPUs, assuming the same | |
705 | * speed as the bootup CPU. (cpufreq notifiers will fix this | |
706 | * up if their speed diverges) | |
707 | */ | |
708 | for_each_possible_cpu(cpu) | |
709 | set_cyc2ns_scale(cpu_khz, cpu); | |
710 | ||
711 | if (tsc_disabled > 0) | |
712 | return; | |
713 | ||
714 | /* now allow native_sched_clock() to use rdtsc */ | |
715 | tsc_disabled = 0; | |
716 | ||
717 | use_tsc_delay(); | |
718 | /* Check and install the TSC clocksource */ | |
719 | dmi_check_system(bad_tsc_dmi_table); | |
720 | ||
721 | if (unsynchronized_tsc()) | |
722 | mark_tsc_unstable("TSCs unsynchronized"); | |
723 | ||
724 | check_geode_tsc_reliable(); | |
725 | init_tsc_clocksource(); | |
726 | } | |
727 |