x86_64: Consolidate tsc calibration

Move the TSC calibration code to tsc.c. Reimplement it so the
pm timer can be used as a reference as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

3 files changed, 92 insertions, 80 deletions

diff --git a/arch/x86/kernel/hpet_64.c b/arch/x86/kernel/hpet_64.c
index e2d1b912e154..1ebce2ec7eaf 100644
--- a/arch/x86/kernel/hpet_64.c
+++ b/arch/x86/kernel/hpet_64.c
@@ -184,55 +184,6 @@ int hpet_reenable(void)
         return hpet_timer_stop_set_go(hpet_tick);
 }
 
-/*
- * calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
- * it to the HPET timer of known frequency.
- */
-
-#define TICK_COUNT 100000000
-#define SMI_THRESHOLD 50000
-#define MAX_TRIES  5
-
-/*
- * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
- * occurs between the reads of the hpet & TSC.
- */
-static void __init read_hpet_tsc(int *hpet, int *tsc)
-{
-        int tsc1, tsc2, hpet1, i;
-
-        for (i = 0; i < MAX_TRIES; i++) {
-                tsc1 = get_cycles_sync();
-                hpet1 = hpet_readl(HPET_COUNTER);
-                tsc2 = get_cycles_sync();
-                if ((tsc2 - tsc1) < SMI_THRESHOLD)
-                        break;
-        }
-        *hpet = hpet1;
-        *tsc = tsc2;
-}
-
-unsigned int __init hpet_calibrate_tsc(void)
-{
-        int tsc_start, hpet_start;
-        int tsc_now, hpet_now;
-        unsigned long flags;
-
-        local_irq_save(flags);
-
-        read_hpet_tsc(&hpet_start, &tsc_start);
-
-        do {
-                local_irq_disable();
-                read_hpet_tsc(&hpet_now, &tsc_now);
-                local_irq_restore(flags);
-        } while ((tsc_now - tsc_start) < TICK_COUNT &&
-                (hpet_now - hpet_start) < TICK_COUNT);
-
-        return (tsc_now - tsc_start) * 1000000000L
-                / ((hpet_now - hpet_start) * hpet_period / 1000);
-}
-
 #ifdef CONFIG_HPET_EMULATE_RTC
 /* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
  * is enabled, we support RTC interrupt functionality in software.
diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c
index 2db4d698a2d3..e97a3ee13551 100644
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -292,35 +292,6 @@ static unsigned int __init tsc_calibrate_cpu_khz(void)
         return pmc_now * tsc_khz / (tsc_now - tsc_start);
 }
 
-/*
- * pit_calibrate_tsc() uses the speaker output (channel 2) of
- * the PIT. This is better than using the timer interrupt output,
- * because we can read the value of the speaker with just one inb(),
- * where we need three i/o operations for the interrupt channel.
- * We count how many ticks the TSC does in 50 ms.
- */
-
-static unsigned int __init pit_calibrate_tsc(void)
-{
-        unsigned long start, end;
-        unsigned long flags;
-
-        spin_lock_irqsave(&i8253_lock, flags);
-
-        outb((inb(0x61) & ~0x02) | 0x01, 0x61);
-
-        outb(0xb0, 0x43);
-        outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
-        outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
-        start = get_cycles_sync();
-        while ((inb(0x61) & 0x20) == 0);
-        end = get_cycles_sync();
-
-        spin_unlock_irqrestore(&i8253_lock, flags);
-
-        return (end - start) / 50;
-}
-
 #define PIT_MODE 0x43
 #define PIT_CH0  0x40
 
@@ -376,14 +347,14 @@ void __init time_init(void)
         if (hpet_use_timer) {
                 /* set tick_nsec to use the proper rate for HPET */
                 tick_nsec = TICK_NSEC_HPET;
-                tsc_khz = hpet_calibrate_tsc();
                 timename = "HPET";
         } else {
                 pit_init();
-                tsc_khz = pit_calibrate_tsc();
                 timename = "PIT";
         }
 
+        tsc_calibrate();
+
         cpu_khz = tsc_khz;
         if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
                 boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c
index 2a59bde663f2..59baecd135ab 100644
--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -6,7 +6,9 @@
 #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;
@@ -118,6 +120,94 @@ 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;
+}
+
 /*
  * Make an educated guess if the TSC is trustworthy and synchronized
  * over all CPUs.