2 * linux/arch/x86-64/kernel/time.c
4 * "High Precision Event Timer" based timekeeping.
6 * Copyright (c) 1991,1992,1995 Linus Torvalds
7 * Copyright (c) 1994 Alan Modra
8 * Copyright (c) 1995 Markus Kuhn
9 * Copyright (c) 1996 Ingo Molnar
10 * Copyright (c) 1998 Andrea Arcangeli
11 * Copyright (c) 2002,2006 Vojtech Pavlik
12 * Copyright (c) 2003 Andi Kleen
13 * RTC support code taken from arch/i386/kernel/timers/time_hpet.c
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/interrupt.h>
19 #include <linux/init.h>
20 #include <linux/mc146818rtc.h>
21 #include <linux/time.h>
22 #include <linux/ioport.h>
23 #include <linux/module.h>
24 #include <linux/device.h>
25 #include <linux/sysdev.h>
26 #include <linux/bcd.h>
27 #include <linux/notifier.h>
28 #include <linux/cpu.h>
29 #include <linux/kallsyms.h>
30 #include <linux/acpi.h>
32 #include <acpi/achware.h> /* for PM timer frequency */
33 #include <acpi/acpi_bus.h>
35 #include <asm/8253pit.h>
36 #include <asm/pgtable.h>
37 #include <asm/vsyscall.h>
38 #include <asm/timex.h>
39 #include <asm/proto.h>
41 #include <asm/sections.h>
42 #include <linux/hpet.h>
45 #include <asm/mpspec.h>
47 #include <asm/vgtod.h>
49 static char *timename = NULL;
51 DEFINE_SPINLOCK(rtc_lock);
52 EXPORT_SYMBOL(rtc_lock);
53 DEFINE_SPINLOCK(i8253_lock);
55 volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
57 unsigned long profile_pc(struct pt_regs *regs)
59 unsigned long pc = instruction_pointer(regs);
61 /* Assume the lock function has either no stack frame or a copy
63 Eflags always has bits 22 and up cleared unlike kernel addresses. */
64 if (!user_mode(regs) && in_lock_functions(pc)) {
65 unsigned long *sp = (unsigned long *)regs->rsp;
73 EXPORT_SYMBOL(profile_pc);
76 * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
77 * ms after the second nowtime has started, because when nowtime is written
78 * into the registers of the CMOS clock, it will jump to the next second
79 * precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
83 static int set_rtc_mmss(unsigned long nowtime)
86 int real_seconds, real_minutes, cmos_minutes;
87 unsigned char control, freq_select;
90 * IRQs are disabled when we're called from the timer interrupt,
91 * no need for spin_lock_irqsave()
97 * Tell the clock it's being set and stop it.
100 control = CMOS_READ(RTC_CONTROL);
101 CMOS_WRITE(control | RTC_SET, RTC_CONTROL);
103 freq_select = CMOS_READ(RTC_FREQ_SELECT);
104 CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
106 cmos_minutes = CMOS_READ(RTC_MINUTES);
107 BCD_TO_BIN(cmos_minutes);
110 * since we're only adjusting minutes and seconds, don't interfere with hour
111 * overflow. This avoids messing with unknown time zones but requires your RTC
112 * not to be off by more than 15 minutes. Since we're calling it only when
113 * our clock is externally synchronized using NTP, this shouldn't be a problem.
116 real_seconds = nowtime % 60;
117 real_minutes = nowtime / 60;
118 if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
119 real_minutes += 30; /* correct for half hour time zone */
122 if (abs(real_minutes - cmos_minutes) >= 30) {
123 printk(KERN_WARNING "time.c: can't update CMOS clock "
124 "from %d to %d\n", cmos_minutes, real_minutes);
127 BIN_TO_BCD(real_seconds);
128 BIN_TO_BCD(real_minutes);
129 CMOS_WRITE(real_seconds, RTC_SECONDS);
130 CMOS_WRITE(real_minutes, RTC_MINUTES);
134 * The following flags have to be released exactly in this order, otherwise the
135 * DS12887 (popular MC146818A clone with integrated battery and quartz) will
136 * not reset the oscillator and will not update precisely 500 ms later. You
137 * won't find this mentioned in the Dallas Semiconductor data sheets, but who
138 * believes data sheets anyway ... -- Markus Kuhn
141 CMOS_WRITE(control, RTC_CONTROL);
142 CMOS_WRITE(freq_select, RTC_FREQ_SELECT);
144 spin_unlock(&rtc_lock);
149 int update_persistent_clock(struct timespec now)
151 return set_rtc_mmss(now.tv_sec);
154 void main_timer_handler(void)
157 * Here we are in the timer irq handler. We have irqs locally disabled (so we
158 * don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
159 * on the other CPU, so we need a lock. We also need to lock the vsyscall
160 * variables, because both do_timer() and us change them -arca+vojtech
163 write_seqlock(&xtime_lock);
166 * Do the timer stuff.
171 update_process_times(user_mode(get_irq_regs()));
175 * In the SMP case we use the local APIC timer interrupt to do the profiling,
176 * except when we simulate SMP mode on a uniprocessor system, in that case we
177 * have to call the local interrupt handler.
180 if (!using_apic_timer)
181 smp_local_timer_interrupt();
183 write_sequnlock(&xtime_lock);
186 static irqreturn_t timer_interrupt(int irq, void *dev_id)
188 if (apic_runs_main_timer > 1)
190 main_timer_handler();
191 if (using_apic_timer)
192 smp_send_timer_broadcast_ipi();
196 static unsigned long get_cmos_time(void)
198 unsigned int year, mon, day, hour, min, sec;
200 unsigned century = 0;
202 spin_lock_irqsave(&rtc_lock, flags);
205 sec = CMOS_READ(RTC_SECONDS);
206 min = CMOS_READ(RTC_MINUTES);
207 hour = CMOS_READ(RTC_HOURS);
208 day = CMOS_READ(RTC_DAY_OF_MONTH);
209 mon = CMOS_READ(RTC_MONTH);
210 year = CMOS_READ(RTC_YEAR);
212 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
213 acpi_gbl_FADT.century)
214 century = CMOS_READ(acpi_gbl_FADT.century);
216 } while (sec != CMOS_READ(RTC_SECONDS));
218 spin_unlock_irqrestore(&rtc_lock, flags);
221 * We know that x86-64 always uses BCD format, no need to check the
234 year += century * 100;
235 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
238 * x86-64 systems only exists since 2002.
239 * This will work up to Dec 31, 2100
244 return mktime(year, mon, day, hour, min, sec);
247 /* calibrate_cpu is used on systems with fixed rate TSCs to determine
248 * processor frequency */
249 #define TICK_COUNT 100000000
250 static unsigned int __init tsc_calibrate_cpu_khz(void)
252 int tsc_start, tsc_now;
254 unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
257 for (i = 0; i < 4; i++)
258 if (avail_to_resrv_perfctr_nmi_bit(i))
260 no_ctr_free = (i == 4);
263 rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
264 wrmsrl(MSR_K7_EVNTSEL3, 0);
265 rdmsrl(MSR_K7_PERFCTR3, pmc3);
267 reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
268 reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
270 local_irq_save(flags);
271 /* start meauring cycles, incrementing from 0 */
272 wrmsrl(MSR_K7_PERFCTR0 + i, 0);
273 wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
276 rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
277 tsc_now = get_cycles_sync();
278 } while ((tsc_now - tsc_start) < TICK_COUNT);
280 local_irq_restore(flags);
282 wrmsrl(MSR_K7_EVNTSEL3, 0);
283 wrmsrl(MSR_K7_PERFCTR3, pmc3);
284 wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
286 release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
287 release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
290 return pmc_now * tsc_khz / (tsc_now - tsc_start);
294 * pit_calibrate_tsc() uses the speaker output (channel 2) of
295 * the PIT. This is better than using the timer interrupt output,
296 * because we can read the value of the speaker with just one inb(),
297 * where we need three i/o operations for the interrupt channel.
298 * We count how many ticks the TSC does in 50 ms.
301 static unsigned int __init pit_calibrate_tsc(void)
303 unsigned long start, end;
306 spin_lock_irqsave(&i8253_lock, flags);
308 outb((inb(0x61) & ~0x02) | 0x01, 0x61);
311 outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
312 outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
313 start = get_cycles_sync();
314 while ((inb(0x61) & 0x20) == 0);
315 end = get_cycles_sync();
317 spin_unlock_irqrestore(&i8253_lock, flags);
319 return (end - start) / 50;
322 #define PIT_MODE 0x43
325 static void __pit_init(int val, u8 mode)
329 spin_lock_irqsave(&i8253_lock, flags);
330 outb_p(mode, PIT_MODE);
331 outb_p(val & 0xff, PIT_CH0); /* LSB */
332 outb_p(val >> 8, PIT_CH0); /* MSB */
333 spin_unlock_irqrestore(&i8253_lock, flags);
336 void __init pit_init(void)
338 __pit_init(LATCH, 0x34); /* binary, mode 2, LSB/MSB, ch 0 */
341 void pit_stop_interrupt(void)
343 __pit_init(0, 0x30); /* mode 0 */
346 void stop_timer_interrupt(void)
351 hpet_timer_stop_set_go(0);
354 pit_stop_interrupt();
356 printk(KERN_INFO "timer: %s interrupt stopped.\n", name);
359 static struct irqaction irq0 = {
360 .handler = timer_interrupt,
361 .flags = IRQF_DISABLED | IRQF_IRQPOLL,
362 .mask = CPU_MASK_NONE,
366 void __init time_init(void)
370 xtime.tv_sec = get_cmos_time();
373 set_normalized_timespec(&wall_to_monotonic,
374 -xtime.tv_sec, -xtime.tv_nsec);
376 if (hpet_arch_init())
379 if (hpet_use_timer) {
380 /* set tick_nsec to use the proper rate for HPET */
381 tick_nsec = TICK_NSEC_HPET;
382 tsc_khz = hpet_calibrate_tsc();
386 tsc_khz = pit_calibrate_tsc();
391 if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
392 boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
393 boot_cpu_data.x86 == 16)
394 cpu_khz = tsc_calibrate_cpu_khz();
396 if (unsynchronized_tsc())
397 mark_tsc_unstable("TSCs unsynchronized");
399 if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
400 vgetcpu_mode = VGETCPU_RDTSCP;
402 vgetcpu_mode = VGETCPU_LSL;
404 set_cyc2ns_scale(tsc_khz);
405 printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
406 cpu_khz / 1000, cpu_khz % 1000);
407 init_tsc_clocksource();
413 static long clock_cmos_diff;
414 static unsigned long sleep_start;
417 * sysfs support for the timer.
420 static int timer_suspend(struct sys_device *dev, pm_message_t state)
423 * Estimate time zone so that set_time can update the clock
425 long cmos_time = get_cmos_time();
427 clock_cmos_diff = -cmos_time;
428 clock_cmos_diff += get_seconds();
429 sleep_start = cmos_time;
433 static int timer_resume(struct sys_device *dev)
437 unsigned long ctime = get_cmos_time();
438 long sleep_length = (ctime - sleep_start) * HZ;
440 if (sleep_length < 0) {
441 printk(KERN_WARNING "Time skew detected in timer resume!\n");
442 /* The time after the resume must not be earlier than the time
443 * before the suspend or some nasty things will happen
451 i8254_timer_resume();
453 sec = ctime + clock_cmos_diff;
454 write_seqlock_irqsave(&xtime_lock,flags);
457 jiffies += sleep_length;
458 write_sequnlock_irqrestore(&xtime_lock,flags);
459 touch_softlockup_watchdog();
463 static struct sysdev_class timer_sysclass = {
464 .resume = timer_resume,
465 .suspend = timer_suspend,
466 set_kset_name("timer"),
469 /* XXX this sysfs stuff should probably go elsewhere later -john */
470 static struct sys_device device_timer = {
472 .cls = &timer_sysclass,
475 static int time_init_device(void)
477 int error = sysdev_class_register(&timer_sysclass);
479 error = sysdev_register(&device_timer);
483 device_initcall(time_init_device);