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_vm(regs) && in_lock_functions(pc)) {
  37 #ifdef CONFIG_FRAME_POINTER
  38                 return *(unsigned long *)(regs->bp + sizeof(long));
  39 #else
  40                 unsigned long *sp = (unsigned long *)regs->sp;
  41                 if (sp[0] >> 22)
  42                         return sp[0];
  43                 if (sp[1] >> 22)
  44                         return sp[1];
  45 #endif
  46         }
  47         return pc;
  48 }
  49 EXPORT_SYMBOL(profile_pc);
  50
  51 static irqreturn_t timer_event_interrupt(int irq, void *dev_id)
  52 {
  53         add_pda(irq0_irqs, 1);
  54
  55         global_clock_event->event_handler(global_clock_event);
  56
  57         return IRQ_HANDLED;
  58 }
  59
  60 /* calibrate_cpu is used on systems with fixed rate TSCs to determine
  61  * processor frequency */
  62 #define TICK_COUNT 100000000
  63 unsigned long __init calibrate_cpu(void)
  64 {
  65         int tsc_start, tsc_now;
  66         int i, no_ctr_free;
  67         unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
  68         unsigned long flags;
  69
  70         for (i = 0; i < 4; i++)
  71                 if (avail_to_resrv_perfctr_nmi_bit(i))
  72                         break;
  73         no_ctr_free = (i == 4);
  74         if (no_ctr_free) {
  75                 i = 3;
  76                 rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
  77                 wrmsrl(MSR_K7_EVNTSEL3, 0);
  78                 rdmsrl(MSR_K7_PERFCTR3, pmc3);
  79         } else {
  80                 reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
  81                 reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
  82         }
  83         local_irq_save(flags);
  84         /* start measuring cycles, incrementing from 0 */
  85         wrmsrl(MSR_K7_PERFCTR0 + i, 0);
  86         wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
  87         rdtscl(tsc_start);
  88         do {
  89                 rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
  90                 tsc_now = get_cycles();
  91         } while ((tsc_now - tsc_start) < TICK_COUNT);
  92
  93         local_irq_restore(flags);
  94         if (no_ctr_free) {
  95                 wrmsrl(MSR_K7_EVNTSEL3, 0);
  96                 wrmsrl(MSR_K7_PERFCTR3, pmc3);
  97                 wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
  98         } else {
  99                 release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
 100                 release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
 101         }
 102
 103         return pmc_now * tsc_khz / (tsc_now - tsc_start);
 104 }
 105
 106 static struct irqaction irq0 = {
 107         .handler        = timer_event_interrupt,
 108         .flags          = IRQF_DISABLED | IRQF_IRQPOLL | IRQF_NOBALANCING,
 109         .mask           = CPU_MASK_NONE,
 110         .name           = "timer"
 111 };
 112
 113 void __init hpet_time_init(void)
 114 {
 115         if (!hpet_enable())
 116                 setup_pit_timer();
 117
 118         irq0.mask = cpumask_of_cpu(0);
 119         setup_irq(0, &irq0);
 120 }
 121
 122 void __init time_init(void)
 123 {
 124         tsc_init();
 125         if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
 126                 vgetcpu_mode = VGETCPU_RDTSCP;
 127         else
 128                 vgetcpu_mode = VGETCPU_LSL;
 129
 130         late_time_init = choose_time_init();
 131 }