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>
31 #include <linux/clockchips.h>
34 #include <acpi/achware.h> /* for PM timer frequency */
35 #include <acpi/acpi_bus.h>
37 #include <asm/i8253.h>
38 #include <asm/pgtable.h>
39 #include <asm/vsyscall.h>
40 #include <asm/timex.h>
41 #include <asm/proto.h>
43 #include <asm/sections.h>
44 #include <linux/hpet.h>
47 #include <asm/mpspec.h>
49 #include <asm/vgtod.h>
51 DEFINE_SPINLOCK(rtc_lock);
52 EXPORT_SYMBOL(rtc_lock);
54 volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
56 unsigned long profile_pc(struct pt_regs *regs)
58 unsigned long pc = instruction_pointer(regs);
60 /* Assume the lock function has either no stack frame or a copy
62 Eflags always has bits 22 and up cleared unlike kernel addresses. */
63 if (!user_mode(regs) && in_lock_functions(pc)) {
64 unsigned long *sp = (unsigned long *)regs->rsp;
72 EXPORT_SYMBOL(profile_pc);
75 * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
76 * ms after the second nowtime has started, because when nowtime is written
77 * into the registers of the CMOS clock, it will jump to the next second
78 * precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
82 static int set_rtc_mmss(unsigned long nowtime)
85 int real_seconds, real_minutes, cmos_minutes;
86 unsigned char control, freq_select;
89 * IRQs are disabled when we're called from the timer interrupt,
90 * no need for spin_lock_irqsave()
96 * Tell the clock it's being set and stop it.
99 control = CMOS_READ(RTC_CONTROL);
100 CMOS_WRITE(control | RTC_SET, RTC_CONTROL);
102 freq_select = CMOS_READ(RTC_FREQ_SELECT);
103 CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
105 cmos_minutes = CMOS_READ(RTC_MINUTES);
106 BCD_TO_BIN(cmos_minutes);
109 * since we're only adjusting minutes and seconds, don't interfere with hour
110 * overflow. This avoids messing with unknown time zones but requires your RTC
111 * not to be off by more than 15 minutes. Since we're calling it only when
112 * our clock is externally synchronized using NTP, this shouldn't be a problem.
115 real_seconds = nowtime % 60;
116 real_minutes = nowtime / 60;
117 if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
118 real_minutes += 30; /* correct for half hour time zone */
121 if (abs(real_minutes - cmos_minutes) >= 30) {
122 printk(KERN_WARNING "time.c: can't update CMOS clock "
123 "from %d to %d\n", cmos_minutes, real_minutes);
126 BIN_TO_BCD(real_seconds);
127 BIN_TO_BCD(real_minutes);
128 CMOS_WRITE(real_seconds, RTC_SECONDS);
129 CMOS_WRITE(real_minutes, RTC_MINUTES);
133 * The following flags have to be released exactly in this order, otherwise the
134 * DS12887 (popular MC146818A clone with integrated battery and quartz) will
135 * not reset the oscillator and will not update precisely 500 ms later. You
136 * won't find this mentioned in the Dallas Semiconductor data sheets, but who
137 * believes data sheets anyway ... -- Markus Kuhn
140 CMOS_WRITE(control, RTC_CONTROL);
141 CMOS_WRITE(freq_select, RTC_FREQ_SELECT);
143 spin_unlock(&rtc_lock);
148 int update_persistent_clock(struct timespec now)
150 return set_rtc_mmss(now.tv_sec);
153 void main_timer_handler(void)
156 * Here we are in the timer irq handler. We have irqs locally disabled (so we
157 * don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
158 * on the other CPU, so we need a lock. We also need to lock the vsyscall
159 * variables, because both do_timer() and us change them -arca+vojtech
162 write_seqlock(&xtime_lock);
165 * Do the timer stuff.
170 update_process_times(user_mode(get_irq_regs()));
174 * In the SMP case we use the local APIC timer interrupt to do the profiling,
175 * except when we simulate SMP mode on a uniprocessor system, in that case we
176 * have to call the local interrupt handler.
179 if (!using_apic_timer)
180 smp_local_timer_interrupt();
182 write_sequnlock(&xtime_lock);
185 static irqreturn_t timer_interrupt(int irq, void *dev_id)
187 if (apic_runs_main_timer > 1)
189 main_timer_handler();
190 if (using_apic_timer)
191 smp_send_timer_broadcast_ipi();
195 static irqreturn_t timer_event_interrupt(int irq, void *dev_id)
197 add_pda(irq0_irqs, 1);
199 global_clock_event->event_handler(global_clock_event);
204 unsigned long read_persistent_clock(void)
206 unsigned int year, mon, day, hour, min, sec;
208 unsigned century = 0;
210 spin_lock_irqsave(&rtc_lock, flags);
213 sec = CMOS_READ(RTC_SECONDS);
214 min = CMOS_READ(RTC_MINUTES);
215 hour = CMOS_READ(RTC_HOURS);
216 day = CMOS_READ(RTC_DAY_OF_MONTH);
217 mon = CMOS_READ(RTC_MONTH);
218 year = CMOS_READ(RTC_YEAR);
220 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
221 acpi_gbl_FADT.century)
222 century = CMOS_READ(acpi_gbl_FADT.century);
224 } while (sec != CMOS_READ(RTC_SECONDS));
226 spin_unlock_irqrestore(&rtc_lock, flags);
229 * We know that x86-64 always uses BCD format, no need to check the
242 year += century * 100;
243 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
246 * x86-64 systems only exists since 2002.
247 * This will work up to Dec 31, 2100
252 return mktime(year, mon, day, hour, min, sec);
255 /* calibrate_cpu is used on systems with fixed rate TSCs to determine
256 * processor frequency */
257 #define TICK_COUNT 100000000
258 static unsigned int __init tsc_calibrate_cpu_khz(void)
260 int tsc_start, tsc_now;
262 unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
265 for (i = 0; i < 4; i++)
266 if (avail_to_resrv_perfctr_nmi_bit(i))
268 no_ctr_free = (i == 4);
271 rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
272 wrmsrl(MSR_K7_EVNTSEL3, 0);
273 rdmsrl(MSR_K7_PERFCTR3, pmc3);
275 reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
276 reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
278 local_irq_save(flags);
279 /* start meauring cycles, incrementing from 0 */
280 wrmsrl(MSR_K7_PERFCTR0 + i, 0);
281 wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
284 rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
285 tsc_now = get_cycles_sync();
286 } while ((tsc_now - tsc_start) < TICK_COUNT);
288 local_irq_restore(flags);
290 wrmsrl(MSR_K7_EVNTSEL3, 0);
291 wrmsrl(MSR_K7_PERFCTR3, pmc3);
292 wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
294 release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
295 release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
298 return pmc_now * tsc_khz / (tsc_now - tsc_start);
301 static struct irqaction irq0 = {
302 .handler = timer_event_interrupt,
303 .flags = IRQF_DISABLED | IRQF_IRQPOLL | IRQF_NOBALANCING,
304 .mask = CPU_MASK_NONE,
308 void __init time_init(void)
318 if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
319 boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
320 boot_cpu_data.x86 == 16)
321 cpu_khz = tsc_calibrate_cpu_khz();
323 if (unsynchronized_tsc())
324 mark_tsc_unstable("TSCs unsynchronized");
326 if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
327 vgetcpu_mode = VGETCPU_RDTSCP;
329 vgetcpu_mode = VGETCPU_LSL;
331 set_cyc2ns_scale(tsc_khz);
332 printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
333 cpu_khz / 1000, cpu_khz % 1000);
334 init_tsc_clocksource();