arch/x86/kernel/time_64.c

   1 /*
   2  *  "High Precision Event Timer" based timekeeping.
   3  *
   4  *  Copyright (c) 1991,1992,1995  Linus Torvalds
   5  *  Copyright (c) 1994  Alan Modra
   6  *  Copyright (c) 1995  Markus Kuhn
   7  *  Copyright (c) 1996  Ingo Molnar
   8  *  Copyright (c) 1998  Andrea Arcangeli
   9  *  Copyright (c) 2002,2006  Vojtech Pavlik
  10  *  Copyright (c) 2003  Andi Kleen
  11  *  RTC support code taken from arch/i386/kernel/timers/time_hpet.c
  12  */
  13
  14 #include <linux/clockchips.h>
  15 #include <linux/init.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/module.h>
  18 #include <linux/time.h>
  19
  20 #include <asm/i8253.h>
  21 #include <asm/hpet.h>
  22 #include <asm/nmi.h>
  23 #include <asm/vgtod.h>
  24 #include <asm/time.h>
  25 #include <asm/timer.h>
  26
  27 volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
  28
  29 unsigned long profile_pc(struct pt_regs *regs)
  30 {
  31         unsigned long pc = instruction_pointer(regs);
  32
  33         /* Assume the lock function has either no stack frame or a copy
  34            of flags from PUSHF
  35            Eflags always has bits 22 and up cleared unlike kernel addresses. */
  36         if (!user_mode(regs) && in_lock_functions(pc)) {
  37                 unsigned long *sp = (unsigned long *)regs->sp;
  38                 if (sp[0] >> 22)
  39                         return sp[0];
  40                 if (sp[1] >> 22)
  41                         return sp[1];
  42         }
  43         return pc;
  44 }
  45 EXPORT_SYMBOL(profile_pc);
  46
  47 static irqreturn_t timer_event_interrupt(int irq, void *dev_id)
  48 {
  49         add_pda(irq0_irqs, 1);
  50
  51         global_clock_event->event_handler(global_clock_event);
  52
  53         return IRQ_HANDLED;
  54 }
  55
  56 /* calibrate_cpu is used on systems with fixed rate TSCs to determine
  57  * processor frequency */
  58 #define TICK_COUNT 100000000
  59 unsigned long __init calibrate_cpu(void)
  60 {
  61         int tsc_start, tsc_now;
  62         int i, no_ctr_free;
  63         unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
  64         unsigned long flags;
  65
  66         for (i = 0; i < 4; i++)
  67                 if (avail_to_resrv_perfctr_nmi_bit(i))
  68                         break;
  69         no_ctr_free = (i == 4);
  70         if (no_ctr_free) {
  71                 i = 3;
  72                 rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
  73                 wrmsrl(MSR_K7_EVNTSEL3, 0);
  74                 rdmsrl(MSR_K7_PERFCTR3, pmc3);
  75         } else {
  76                 reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
  77                 reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
  78         }
  79         local_irq_save(flags);
  80         /* start measuring cycles, incrementing from 0 */
  81         wrmsrl(MSR_K7_PERFCTR0 + i, 0);
  82         wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
  83         rdtscl(tsc_start);
  84         do {
  85                 rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
  86                 tsc_now = get_cycles();
  87         } while ((tsc_now - tsc_start) < TICK_COUNT);
  88
  89         local_irq_restore(flags);
  90         if (no_ctr_free) {
  91                 wrmsrl(MSR_K7_EVNTSEL3, 0);
  92                 wrmsrl(MSR_K7_PERFCTR3, pmc3);
  93                 wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
  94         } else {
  95                 release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
  96                 release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
  97         }
  98
  99         return pmc_now * tsc_khz / (tsc_now - tsc_start);
 100 }
 101
 102 static struct irqaction irq0 = {
 103         .handler        = timer_event_interrupt,
 104         .flags          = IRQF_DISABLED | IRQF_IRQPOLL | IRQF_NOBALANCING,
 105         .mask           = CPU_MASK_NONE,
 106         .name           = "timer"
 107 };
 108
 109 void __init hpet_time_init(void)
 110 {
 111         if (!hpet_enable())
 112                 setup_pit_timer();
 113
 114         setup_irq(0, &irq0);
 115 }
 116
 117 void __init time_init(void)
 118 {
 119         tsc_init();
 120         if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
 121                 vgetcpu_mode = VGETCPU_RDTSCP;
 122         else
 123                 vgetcpu_mode = VGETCPU_LSL;
 124
 125         late_time_init = choose_time_init();
 126 }