1 files changed, 64 insertions, 131 deletions

diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 2cfc7b09b925..3082a418635c 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -23,6 +23,7 @@
  * an extra value to store the TSC freq
  */
 unsigned int tsc_khz;
+unsigned long long (*custom_sched_clock)(void);
 
 int tsc_disable;
 
@@ -59,12 +60,6 @@ static inline int check_tsc_unstable(void)
         return tsc_unstable;
 }
 
-void mark_tsc_unstable(void)
-{
-        tsc_unstable = 1;
-}
-EXPORT_SYMBOL_GPL(mark_tsc_unstable);
-
 /* Accellerators for sched_clock()
  * convert from cycles(64bits) => nanoseconds (64bits)
  *  basic equation:
@@ -107,14 +102,14 @@ unsigned long long sched_clock(void)
 {
         unsigned long long this_offset;
 
+        if (unlikely(custom_sched_clock))
+                return (*custom_sched_clock)();
+
         /*
-         * in the NUMA case we dont use the TSC as they are not
-         * synchronized across all CPUs.
+         * Fall back to jiffies if there's no TSC available:
          */
-#ifndef CONFIG_NUMA
-        if (!cpu_khz || check_tsc_unstable())
-#endif
-                /* no locking but a rare wrong value is not a big deal */
+        if (unlikely(tsc_disable))
+                /* No locking but a rare wrong value is not a big deal: */
                 return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
 
         /* read the Time Stamp Counter: */
@@ -194,13 +189,13 @@ EXPORT_SYMBOL(recalibrate_cpu_khz);
 void __init tsc_init(void)
 {
         if (!cpu_has_tsc || tsc_disable)
-                return;
+                goto out_no_tsc;
 
         cpu_khz = calculate_cpu_khz();
         tsc_khz = cpu_khz;
 
         if (!cpu_khz)
-                return;
+                goto out_no_tsc;
 
         printk("Detected %lu.%03lu MHz processor.\n",
                                 (unsigned long)cpu_khz / 1000,
@@ -208,37 +203,18 @@ void __init tsc_init(void)
 
         set_cyc2ns_scale(cpu_khz);
         use_tsc_delay();
-}
+        return;
 
-#ifdef CONFIG_CPU_FREQ
-
-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 *work)
-{
-        unsigned int cpu;
-
-        for_each_online_cpu(cpu)
-                cpufreq_get(cpu);
-
-        cpufreq_delayed_issched = 0;
+out_no_tsc:
+        /*
+         * Set the tsc_disable flag if there's no TSC support, this
+         * makes it a fast flag for the kernel to see whether it
+         * should be using the TSC.
+         */
+        tsc_disable = 1;
 }
 
-/*
- * if we notice cpufreq oddness, 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.
- */
-static inline void cpufreq_delayed_get(void)
-{
-        if (cpufreq_init && !cpufreq_delayed_issched) {
-                cpufreq_delayed_issched = 1;
-                printk(KERN_DEBUG "Checking if CPU frequency changed.\n");
-                schedule_work(&cpufreq_delayed_get_work);
-        }
-}
+#ifdef CONFIG_CPU_FREQ
 
 /*
  * if the CPU frequency is scaled, TSC-based delays will need a different
@@ -303,17 +279,9 @@ static struct notifier_block time_cpufreq_notifier_block = {
 
 static int __init cpufreq_tsc(void)
 {
-        int ret;
-
-        INIT_WORK(&cpufreq_delayed_get_work, handle_cpufreq_delayed_get);
-        ret = cpufreq_register_notifier(&time_cpufreq_notifier_block,
-                                        CPUFREQ_TRANSITION_NOTIFIER);
-        if (!ret)
-                cpufreq_init = 1;
-
-        return ret;
+        return cpufreq_register_notifier(&time_cpufreq_notifier_block,
+                                         CPUFREQ_TRANSITION_NOTIFIER);
 }
-
 core_initcall(cpufreq_tsc);
 
 #endif
@@ -321,7 +289,6 @@ core_initcall(cpufreq_tsc);
 /* clock source code */
 
 static unsigned long current_tsc_khz = 0;
-static int tsc_update_callback(void);
 
 static cycle_t read_tsc(void)
 {
@@ -339,37 +306,28 @@ static struct clocksource clocksource_tsc = {
         .mask                   = CLOCKSOURCE_MASK(64),
         .mult                   = 0, /* to be set */
         .shift                  = 22,
-        .update_callback        = tsc_update_callback,
-        .is_continuous          = 1,
+        .flags                  = CLOCK_SOURCE_IS_CONTINUOUS |
+                                  CLOCK_SOURCE_MUST_VERIFY,
 };
 
-static int tsc_update_callback(void)
+void mark_tsc_unstable(void)
 {
-        int change = 0;
-
-        /* check to see if we should switch to the safe clocksource: */
-        if (clocksource_tsc.rating != 0 && check_tsc_unstable()) {
-                clocksource_tsc.rating = 0;
-                clocksource_reselect();
-                change = 1;
-        }
-
-        /* only update if tsc_khz has changed: */
-        if (current_tsc_khz != tsc_khz) {
-                current_tsc_khz = tsc_khz;
-                clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
-                                                        clocksource_tsc.shift);
-                change = 1;
+        if (!tsc_unstable) {
+                tsc_unstable = 1;
+                /* Can be called before registration */
+                if (clocksource_tsc.mult)
+                        clocksource_change_rating(&clocksource_tsc, 0);
+                else
+                        clocksource_tsc.rating = 0;
         }
-
-        return change;
 }
+EXPORT_SYMBOL_GPL(mark_tsc_unstable);
 
 static int __init dmi_mark_tsc_unstable(struct dmi_system_id *d)
 {
         printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
                        d->ident);
-        mark_tsc_unstable();
+        tsc_unstable = 1;
         return 0;
 }
 
@@ -386,65 +344,44 @@ static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
          {}
 };
 
-#define TSC_FREQ_CHECK_INTERVAL (10*MSEC_PER_SEC) /* 10sec in MS */
-static struct timer_list verify_tsc_freq_timer;
-
-/* XXX - Probably should add locking */
-static void verify_tsc_freq(unsigned long unused)
-{
-        static u64 last_tsc;
-        static unsigned long last_jiffies;
-
-        u64 now_tsc, interval_tsc;
-        unsigned long now_jiffies, interval_jiffies;
-
-
-        if (check_tsc_unstable())
-                return;
-
-        rdtscll(now_tsc);
-        now_jiffies = jiffies;
-
-        if (!last_jiffies) {
-                goto out;
-        }
-
-        interval_jiffies = now_jiffies - last_jiffies;
-        interval_tsc = now_tsc - last_tsc;
-        interval_tsc *= HZ;
-        do_div(interval_tsc, cpu_khz*1000);
-
-        if (interval_tsc < (interval_jiffies * 3 / 4)) {
-                printk("TSC appears to be running slowly. "
-                        "Marking it as unstable\n");
-                mark_tsc_unstable();
-                return;
-        }
-
-out:
-        last_tsc = now_tsc;
-        last_jiffies = now_jiffies;
-        /* set us up to go off on the next interval: */
-        mod_timer(&verify_tsc_freq_timer,
-                jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL));
-}
-
 /*
  * Make an educated guess if the TSC is trustworthy and synchronized
  * over all CPUs.
  */
-static __init int unsynchronized_tsc(void)
+__cpuinit int unsynchronized_tsc(void)
 {
+        if (!cpu_has_tsc || tsc_unstable)
+                return 1;
         /*
          * Intel systems are normally all synchronized.
          * Exceptions must mark TSC as unstable:
          */
-        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
-                return 0;
+        if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
+                /* assume multi socket systems are not synchronized: */
+                if (num_possible_cpus() > 1)
+                        tsc_unstable = 1;
+        }
+        return tsc_unstable;
+}
+
+/*
+ * Geode_LX - the OLPC CPU has a possibly a very reliable TSC
+ */
+#ifdef CONFIG_MGEODE_LX
+/* RTSC counts during suspend */
+#define RTSC_SUSP 0x100
+
+static void __init check_geode_tsc_reliable(void)
+{
+        unsigned long val;
 
-        /* assume multi socket systems are not synchronized: */
-        return num_possible_cpus() > 1;
+        rdmsrl(MSR_GEODE_BUSCONT_CONF0, val);
+        if ((val & RTSC_SUSP))
+                clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
 }
+#else
+static inline void check_geode_tsc_reliable(void) { }
+#endif
 
 static int __init init_tsc_clocksource(void)
 {
@@ -453,20 +390,16 @@ static int __init init_tsc_clocksource(void)
                 /* check blacklist */
                 dmi_check_system(bad_tsc_dmi_table);
 
-                if (unsynchronized_tsc()) /* mark unstable if unsynced */
-                        mark_tsc_unstable();
+                unsynchronized_tsc();
+                check_geode_tsc_reliable();
                 current_tsc_khz = tsc_khz;
                 clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
                                                         clocksource_tsc.shift);
                 /* lower the rating if we already know its unstable: */
-                if (check_tsc_unstable())
+                if (check_tsc_unstable()) {
                         clocksource_tsc.rating = 0;
-
-                init_timer(&verify_tsc_freq_timer);
-                verify_tsc_freq_timer.function = verify_tsc_freq;
-                verify_tsc_freq_timer.expires =
-                        jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL);
-                add_timer(&verify_tsc_freq_timer);
+                        clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
+                }
 
                 return clocksource_register(&clocksource_tsc);
         }