1 files changed, 298 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c
new file mode 100644
index 00000000000..9f22e542c37
--- /dev/null
+++ b/arch/x86/kernel/tsc_64.c
@@ -0,0 +1,298 @@
+#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>
+
+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);
+
+static unsigned int cyc2ns_scale __read_mostly;
+
+static inline void set_cyc2ns_scale(unsigned long khz)
+{
+	cyc2ns_scale = (NSEC_PER_MSEC << NS_SCALE) / khz;
+}
+
+static unsigned long long cycles_2_ns(unsigned long long cyc)
+{
+	return (cyc * cyc2ns_scale) >> NS_SCALE;
+}
+
+unsigned long long 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);
+}
+
+static int tsc_unstable;
+
+inline int check_tsc_unstable(void)
+{
+	return 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);
+
+	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_sync();
+		if (hpet)
+			*hpet = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF;
+		else
+			*pm = acpi_pm_read_early();
+		t2 = get_cycles_sync();
+		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();
+
+	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_sync();
+	while ((inb(0x61) & 0x20) == 0);
+	tr2 = get_cycles_sync();
+
+	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");
+		return;
+	}
+
+	/* 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");
+		return;
+	}
+
+	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;
+	set_cyc2ns_scale(tsc_khz);
+}
+
+/*
+ * 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
+	/* Most intel systems have synchronized TSCs except for
+	   multi node systems */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
+#ifdef CONFIG_ACPI
+		/* But TSC doesn't tick in C3 so don't use it there */
+		if (acpi_gbl_FADT.header.length > 0 &&
+		    acpi_gbl_FADT.C3latency < 1000)
+			return 1;
+#endif
+		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);
+
+
+/* clock source code: */
+static cycle_t read_tsc(void)
+{
+	cycle_t ret = (cycle_t)get_cycles_sync();
+	return ret;
+}
+
+static cycle_t __vsyscall_fn vread_tsc(void)
+{
+	cycle_t ret = (cycle_t)get_cycles_sync();
+	return ret;
+}
+
+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);
+	}
+}