12b4a71bd0748555cac1d552fe96cc8d8e2c19c3
[linux-2.6.git] / 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 native_calculate_cpu_khz(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_calibrate();
120
121         cpu_khz = tsc_khz;
122         if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
123                 (boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
124                 cpu_khz = calculate_cpu_khz();
125
126         lpj_tsc = ((unsigned long)tsc_khz * 1000)/HZ;
127
128         if (unsynchronized_tsc())
129                 mark_tsc_unstable("TSCs unsynchronized");
130
131         if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
132                 vgetcpu_mode = VGETCPU_RDTSCP;
133         else
134                 vgetcpu_mode = VGETCPU_LSL;
135
136         printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
137                 cpu_khz / 1000, cpu_khz % 1000);
138         init_tsc_clocksource();
139         late_time_init = choose_time_init();
140 }