diff options
Diffstat (limited to 'arch/x86/kernel/tsc_64.c')
| -rw-r--r-- | arch/x86/kernel/tsc_64.c | 357 |
1 files changed, 0 insertions, 357 deletions
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c deleted file mode 100644 index 1784b8077a12..000000000000 --- a/arch/x86/kernel/tsc_64.c +++ /dev/null @@ -1,357 +0,0 @@ -#include <linux/kernel.h> -#include <linux/sched.h> -#include <linux/interrupt.h> -#include <linux/init.h> -#include <linux/clocksource.h> -#include <linux/time.h> -#include <linux/acpi.h> -#include <linux/cpufreq.h> -#include <linux/acpi_pmtmr.h> - -#include <asm/hpet.h> -#include <asm/timex.h> -#include <asm/timer.h> -#include <asm/vgtod.h> - -static int notsc __initdata = 0; - -unsigned int cpu_khz; /* TSC clocks / usec, not used here */ -EXPORT_SYMBOL(cpu_khz); -unsigned int tsc_khz; -EXPORT_SYMBOL(tsc_khz); - -/* Accelerators for sched_clock() - * convert from cycles(64bits) => nanoseconds (64bits) - * basic equation: - * ns = cycles / (freq / ns_per_sec) - * ns = cycles * (ns_per_sec / freq) - * ns = cycles * (10^9 / (cpu_khz * 10^3)) - * ns = cycles * (10^6 / cpu_khz) - * - * Then we use scaling math (suggested by george@mvista.com) to get: - * ns = cycles * (10^6 * SC / cpu_khz) / SC - * ns = cycles * cyc2ns_scale / SC - * - * And since SC is a constant power of two, we can convert the div - * into a shift. - * - * We can use khz divisor instead of mhz to keep a better precision, since - * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. - * (mathieu.desnoyers@polymtl.ca) - * - * -johnstul@us.ibm.com "math is hard, lets go shopping!" - */ -DEFINE_PER_CPU(unsigned long, cyc2ns); - -static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) -{ - unsigned long long tsc_now, ns_now; - unsigned long flags, *scale; - - local_irq_save(flags); - sched_clock_idle_sleep_event(); - - scale = &per_cpu(cyc2ns, cpu); - - rdtscll(tsc_now); - ns_now = __cycles_2_ns(tsc_now); - - if (cpu_khz) - *scale = (NSEC_PER_MSEC << CYC2NS_SCALE_FACTOR)/cpu_khz; - - sched_clock_idle_wakeup_event(0); - local_irq_restore(flags); -} - -unsigned long long native_sched_clock(void) -{ - unsigned long a = 0; - - /* Could do CPU core sync here. Opteron can execute rdtsc speculatively, - * which means it is not completely exact and may not be monotonous - * between CPUs. But the errors should be too small to matter for - * scheduling purposes. - */ - - rdtscll(a); - return cycles_2_ns(a); -} - -/* We need to define a real function for sched_clock, to override the - weak default version */ -#ifdef CONFIG_PARAVIRT -unsigned long long sched_clock(void) -{ - return paravirt_sched_clock(); -} -#else -unsigned long long -sched_clock(void) __attribute__((alias("native_sched_clock"))); -#endif - - -static int tsc_unstable; - -int check_tsc_unstable(void) -{ - return tsc_unstable; -} -EXPORT_SYMBOL_GPL(check_tsc_unstable); - -#ifdef CONFIG_CPU_FREQ - -/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency - * changes. - * - * RED-PEN: On SMP we assume all CPUs run with the same frequency. It's - * not that important because current Opteron setups do not support - * scaling on SMP anyroads. - * - * Should fix up last_tsc too. Currently gettimeofday in the - * first tick after the change will be slightly wrong. - */ - -static unsigned int ref_freq; -static unsigned long loops_per_jiffy_ref; -static unsigned long tsc_khz_ref; - -static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, - void *data) -{ - struct cpufreq_freqs *freq = data; - unsigned long *lpj, dummy; - - if (cpu_has(&cpu_data(freq->cpu), X86_FEATURE_CONSTANT_TSC)) - return 0; - - lpj = &dummy; - if (!(freq->flags & CPUFREQ_CONST_LOOPS)) -#ifdef CONFIG_SMP - lpj = &cpu_data(freq->cpu).loops_per_jiffy; -#else - lpj = &boot_cpu_data.loops_per_jiffy; -#endif - - if (!ref_freq) { - ref_freq = freq->old; - loops_per_jiffy_ref = *lpj; - tsc_khz_ref = tsc_khz; - } - if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || - (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) || - (val == CPUFREQ_RESUMECHANGE)) { - *lpj = - cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); - - tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); - if (!(freq->flags & CPUFREQ_CONST_LOOPS)) - mark_tsc_unstable("cpufreq changes"); - } - - set_cyc2ns_scale(tsc_khz_ref, freq->cpu); - - return 0; -} - -static struct notifier_block time_cpufreq_notifier_block = { - .notifier_call = time_cpufreq_notifier -}; - -static int __init cpufreq_tsc(void) -{ - cpufreq_register_notifier(&time_cpufreq_notifier_block, - CPUFREQ_TRANSITION_NOTIFIER); - return 0; -} - -core_initcall(cpufreq_tsc); - -#endif - -#define MAX_RETRIES 5 -#define SMI_TRESHOLD 50000 - -/* - * Read TSC and the reference counters. Take care of SMI disturbance - */ -static unsigned long __init tsc_read_refs(unsigned long *pm, - unsigned long *hpet) -{ - unsigned long t1, t2; - int i; - - for (i = 0; i < MAX_RETRIES; i++) { - t1 = get_cycles(); - if (hpet) - *hpet = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF; - else - *pm = acpi_pm_read_early(); - t2 = get_cycles(); - if ((t2 - t1) < SMI_TRESHOLD) - return t2; - } - return ULONG_MAX; -} - -/** - * tsc_calibrate - calibrate the tsc on boot - */ -void __init tsc_calibrate(void) -{ - unsigned long flags, tsc1, tsc2, tr1, tr2, pm1, pm2, hpet1, hpet2; - int hpet = is_hpet_enabled(), cpu; - - local_irq_save(flags); - - tsc1 = tsc_read_refs(&pm1, hpet ? &hpet1 : NULL); - - outb((inb(0x61) & ~0x02) | 0x01, 0x61); - - outb(0xb0, 0x43); - outb((CLOCK_TICK_RATE / (1000 / 50)) & 0xff, 0x42); - outb((CLOCK_TICK_RATE / (1000 / 50)) >> 8, 0x42); - tr1 = get_cycles(); - while ((inb(0x61) & 0x20) == 0); - tr2 = get_cycles(); - - tsc2 = tsc_read_refs(&pm2, hpet ? &hpet2 : NULL); - - local_irq_restore(flags); - - /* - * Preset the result with the raw and inaccurate PIT - * calibration value - */ - tsc_khz = (tr2 - tr1) / 50; - - /* hpet or pmtimer available ? */ - if (!hpet && !pm1 && !pm2) { - printk(KERN_INFO "TSC calibrated against PIT\n"); - goto out; - } - - /* Check, whether the sampling was disturbed by an SMI */ - if (tsc1 == ULONG_MAX || tsc2 == ULONG_MAX) { - printk(KERN_WARNING "TSC calibration disturbed by SMI, " - "using PIT calibration result\n"); - goto out; - } - - tsc2 = (tsc2 - tsc1) * 1000000L; - - if (hpet) { - printk(KERN_INFO "TSC calibrated against HPET\n"); - if (hpet2 < hpet1) - hpet2 += 0x100000000; - hpet2 -= hpet1; - tsc1 = (hpet2 * hpet_readl(HPET_PERIOD)) / 1000000; - } else { - printk(KERN_INFO "TSC calibrated against PM_TIMER\n"); - if (pm2 < pm1) - pm2 += ACPI_PM_OVRRUN; - pm2 -= pm1; - tsc1 = (pm2 * 1000000000) / PMTMR_TICKS_PER_SEC; - } - - tsc_khz = tsc2 / tsc1; - -out: - for_each_possible_cpu(cpu) - set_cyc2ns_scale(tsc_khz, cpu); -} - -/* - * Make an educated guess if the TSC is trustworthy and synchronized - * over all CPUs. - */ -__cpuinit int unsynchronized_tsc(void) -{ - if (tsc_unstable) - return 1; - -#ifdef CONFIG_SMP - if (apic_is_clustered_box()) - return 1; -#endif - - if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) - return 0; - - /* Assume multi socket systems are not synchronized */ - return num_present_cpus() > 1; -} - -int __init notsc_setup(char *s) -{ - notsc = 1; - return 1; -} - -__setup("notsc", notsc_setup); - -static struct clocksource clocksource_tsc; - -/* - * We compare the TSC to the cycle_last value in the clocksource - * structure to avoid a nasty time-warp. This can be observed in a - * very small window right after one CPU updated cycle_last under - * xtime/vsyscall_gtod lock and the other CPU reads a TSC value which - * is smaller than the cycle_last reference value due to a TSC which - * is slighty behind. This delta is nowhere else observable, but in - * that case it results in a forward time jump in the range of hours - * due to the unsigned delta calculation of the time keeping core - * code, which is necessary to support wrapping clocksources like pm - * timer. - */ -static cycle_t read_tsc(void) -{ - cycle_t ret = (cycle_t)get_cycles(); - - return ret >= clocksource_tsc.cycle_last ? - ret : clocksource_tsc.cycle_last; -} - -static cycle_t __vsyscall_fn vread_tsc(void) -{ - cycle_t ret = (cycle_t)vget_cycles(); - - return ret >= __vsyscall_gtod_data.clock.cycle_last ? - ret : __vsyscall_gtod_data.clock.cycle_last; -} - -static struct clocksource clocksource_tsc = { - .name = "tsc", - .rating = 300, - .read = read_tsc, - .mask = CLOCKSOURCE_MASK(64), - .shift = 22, - .flags = CLOCK_SOURCE_IS_CONTINUOUS | - CLOCK_SOURCE_MUST_VERIFY, - .vread = vread_tsc, -}; - -void mark_tsc_unstable(char *reason) -{ - if (!tsc_unstable) { - tsc_unstable = 1; - printk("Marking TSC unstable due to %s\n", reason); - /* Change only the rating, when not registered */ - if (clocksource_tsc.mult) - clocksource_change_rating(&clocksource_tsc, 0); - else - clocksource_tsc.rating = 0; - } -} -EXPORT_SYMBOL_GPL(mark_tsc_unstable); - -void __init init_tsc_clocksource(void) -{ - if (!notsc) { - clocksource_tsc.mult = clocksource_khz2mult(tsc_khz, - clocksource_tsc.shift); - if (check_tsc_unstable()) - clocksource_tsc.rating = 0; - - clocksource_register(&clocksource_tsc); - } -} |