1 files changed, 212 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/tsc.c b/arch/x86_64/kernel/tsc.c
new file mode 100644
index 000000000000..2dbac15ab1f0
--- /dev/null
+++ b/arch/x86_64/kernel/tsc.c
@@ -0,0 +1,212 @@
+#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 <asm/timex.h>
+
+int notsc __initdata = 0;
+
+unsigned int cpu_khz;           /* TSC clocks / usec, not used here */
+EXPORT_SYMBOL(cpu_khz);
+
+/*
+ * do_gettimeoffset() returns microseconds since last timer interrupt was
+ * triggered by hardware. A memory read of HPET is slower than a register read
+ * of TSC, but much more reliable. It's also synchronized to the timer
+ * interrupt. Note that do_gettimeoffset() may return more than hpet_tick, if a
+ * timer interrupt has happened already, but vxtime.trigger wasn't updated yet.
+ * This is not a problem, because jiffies hasn't updated either. They are bound
+ * together by xtime_lock.
+ */
+
+unsigned int do_gettimeoffset_tsc(void)
+{
+        unsigned long t;
+        unsigned long x;
+        t = get_cycles_sync();
+        if (t < vxtime.last_tsc)
+                t = vxtime.last_tsc; /* hack */
+        x = ((t - vxtime.last_tsc) * vxtime.tsc_quot) >> US_SCALE;
+        return x;
+}
+
+static unsigned int cyc2ns_scale __read_mostly;
+
+void set_cyc2ns_scale(unsigned long khz)
+{
+        cyc2ns_scale = (NSEC_PER_MSEC << NS_SCALE) / khz;
+}
+
+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);
+}
+
+#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.
+ */
+
+#include <linux/workqueue.h>
+
+static unsigned int cpufreq_delayed_issched = 0;
+static unsigned int cpufreq_init = 0;
+static struct work_struct cpufreq_delayed_get_work;
+
+static void handle_cpufreq_delayed_get(struct work_struct *v)
+{
+        unsigned int cpu;
+        for_each_online_cpu(cpu) {
+                cpufreq_get(cpu);
+        }
+        cpufreq_delayed_issched = 0;
+}
+
+/* if we notice lost ticks, schedule a call to cpufreq_get() as it tries
+ * to verify the CPU frequency the timing core thinks the CPU is running
+ * at is still correct.
+ */
+void cpufreq_delayed_get(void)
+{
+        static int warned;
+        if (cpufreq_init && !cpufreq_delayed_issched) {
+                cpufreq_delayed_issched = 1;
+                if (!warned) {
+                        warned = 1;
+                        printk(KERN_DEBUG "Losing some ticks... "
+                                "checking if CPU frequency changed.\n");
+                }
+                schedule_work(&cpufreq_delayed_get_work);
+        }
+}
+
+static unsigned int  ref_freq = 0;
+static unsigned long loops_per_jiffy_ref = 0;
+
+static unsigned long cpu_khz_ref = 0;
+
+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;
+                cpu_khz_ref = cpu_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);
+
+                cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);
+                if (!(freq->flags & CPUFREQ_CONST_LOOPS))
+                        vxtime.tsc_quot = (USEC_PER_MSEC << US_SCALE) / cpu_khz;
+        }
+
+        set_cyc2ns_scale(cpu_khz_ref);
+
+        return 0;
+}
+
+static struct notifier_block time_cpufreq_notifier_block = {
+        .notifier_call  = time_cpufreq_notifier
+};
+
+static int __init cpufreq_tsc(void)
+{
+        INIT_WORK(&cpufreq_delayed_get_work, handle_cpufreq_delayed_get);
+        if (!cpufreq_register_notifier(&time_cpufreq_notifier_block,
+                                       CPUFREQ_TRANSITION_NOTIFIER))
+                cpufreq_init = 1;
+        return 0;
+}
+
+core_initcall(cpufreq_tsc);
+
+#endif
+
+static int tsc_unstable = 0;
+
+void mark_tsc_unstable(void)
+{
+        tsc_unstable = 1;
+}
+EXPORT_SYMBOL_GPL(mark_tsc_unstable);
+
+/*
+ * 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);