From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 11 Oct 2007 09:13:09 +0000 (+0200)
Subject: i386: prepare shared kernel/tsc.c
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=76ea2ec68b54acc13ee1bfbb9a4e3aad370a374f;p=linux.git
i386: prepare shared kernel/tsc.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index ff2909a974415..d5367aa2510d3 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -7,7 +7,7 @@ extra-y := head.o init_task_32.o vmlinux.lds
obj-y := process_32.o signal_32.o entry_32.o traps_32.o irq_32.o \
ptrace_32.o time_32.o ioport_32.o ldt_32.o setup_32.o i8259_32.o sys_i386_32.o \
pci-dma_32.o i386_ksyms_32.o i387_32.o bootflag.o e820_32.o\
- quirks.o i8237.o topology.o alternative.o i8253_32.o tsc.o
+ quirks.o i8237.o topology.o alternative.o i8253_32.o tsc_32.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
deleted file mode 100644
index a39280b4dd3a5..0000000000000
--- a/arch/i386/kernel/tsc.c
+++ /dev/null
@@ -1,413 +0,0 @@
-/*
- * This code largely moved from arch/i386/kernel/timer/timer_tsc.c
- * which was originally moved from arch/i386/kernel/time.c.
- * See comments there for proper credits.
- */
-
-#include <linux/sched.h>
-#include <linux/clocksource.h>
-#include <linux/workqueue.h>
-#include <linux/cpufreq.h>
-#include <linux/jiffies.h>
-#include <linux/init.h>
-#include <linux/dmi.h>
-
-#include <asm/delay.h>
-#include <asm/tsc.h>
-#include <asm/io.h>
-#include <asm/timer.h>
-
-#include "mach_timer.h"
-
-static int tsc_enabled;
-
-/*
- * On some systems the TSC frequency does not
- * change with the cpu frequency. So we need
- * an extra value to store the TSC freq
- */
-unsigned int tsc_khz;
-EXPORT_SYMBOL_GPL(tsc_khz);
-
-int tsc_disable;
-
-#ifdef CONFIG_X86_TSC
-static int __init tsc_setup(char *str)
-{
- printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
- "cannot disable TSC.\n");
- return 1;
-}
-#else
-/*
- * disable flag for tsc. Takes effect by clearing the TSC cpu flag
- * in cpu/common.c
- */
-static int __init tsc_setup(char *str)
-{
- tsc_disable = 1;
-
- return 1;
-}
-#endif
-
-__setup("notsc", tsc_setup);
-
-/*
- * code to mark and check if the TSC is unstable
- * due to cpufreq or due to unsynced TSCs
- */
-static int tsc_unstable;
-
-int check_tsc_unstable(void)
-{
- return tsc_unstable;
-}
-EXPORT_SYMBOL_GPL(check_tsc_unstable);
-
-/* Accellerators 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 percision, 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!"
- */
-unsigned long cyc2ns_scale __read_mostly;
-
-#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
-
-static inline void set_cyc2ns_scale(unsigned long cpu_khz)
-{
- cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
-}
-
-/*
- * Scheduler clock - returns current time in nanosec units.
- */
-unsigned long long native_sched_clock(void)
-{
- unsigned long long this_offset;
-
- /*
- * Fall back to jiffies if there's no TSC available:
- * ( But note that we still use it if the TSC is marked
- * unstable. We do this because unlike Time Of Day,
- * the scheduler clock tolerates small errors and it's
- * very important for it to be as fast as the platform
- * can achive it. )
- */
- if (unlikely(!tsc_enabled && !tsc_unstable))
- /* No locking but a rare wrong value is not a big deal: */
- return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
-
- /* read the Time Stamp Counter: */
- rdtscll(this_offset);
-
- /* return the value in ns */
- return cycles_2_ns(this_offset);
-}
-
-/* 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
-
-unsigned long native_calculate_cpu_khz(void)
-{
- unsigned long long start, end;
- unsigned long count;
- u64 delta64;
- int i;
- unsigned long flags;
-
- local_irq_save(flags);
-
- /* run 3 times to ensure the cache is warm */
- for (i = 0; i < 3; i++) {
- mach_prepare_counter();
- rdtscll(start);
- mach_countup(&count);
- rdtscll(end);
- }
- /*
- * Error: ECTCNEVERSET
- * The CTC wasn't reliable: we got a hit on the very first read,
- * or the CPU was so fast/slow that the quotient wouldn't fit in
- * 32 bits..
- */
- if (count <= 1)
- goto err;
-
- delta64 = end - start;
-
- /* cpu freq too fast: */
- if (delta64 > (1ULL<<32))
- goto err;
-
- /* cpu freq too slow: */
- if (delta64 <= CALIBRATE_TIME_MSEC)
- goto err;
-
- delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
- do_div(delta64,CALIBRATE_TIME_MSEC);
-
- local_irq_restore(flags);
- return (unsigned long)delta64;
-err:
- local_irq_restore(flags);
- return 0;
-}
-
-int recalibrate_cpu_khz(void)
-{
-#ifndef CONFIG_SMP
- unsigned long cpu_khz_old = cpu_khz;
-
- if (cpu_has_tsc) {
- cpu_khz = calculate_cpu_khz();
- tsc_khz = cpu_khz;
- cpu_data[0].loops_per_jiffy =
- cpufreq_scale(cpu_data[0].loops_per_jiffy,
- cpu_khz_old, cpu_khz);
- return 0;
- } else
- return -ENODEV;
-#else
- return -ENODEV;
-#endif
-}
-
-EXPORT_SYMBOL(recalibrate_cpu_khz);
-
-#ifdef CONFIG_CPU_FREQ
-
-/*
- * if the CPU frequency is scaled, TSC-based delays will need a different
- * loops_per_jiffy value to function properly.
- */
-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;
-
- if (!ref_freq) {
- if (!freq->old){
- ref_freq = freq->new;
- return 0;
- }
- ref_freq = freq->old;
- loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
- cpu_khz_ref = cpu_khz;
- }
-
- if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
- (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
- (val == CPUFREQ_RESUMECHANGE)) {
- if (!(freq->flags & CPUFREQ_CONST_LOOPS))
- cpu_data[freq->cpu].loops_per_jiffy =
- cpufreq_scale(loops_per_jiffy_ref,
- ref_freq, freq->new);
-
- if (cpu_khz) {
-
- if (num_online_cpus() == 1)
- cpu_khz = cpufreq_scale(cpu_khz_ref,
- ref_freq, freq->new);
- if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
- tsc_khz = cpu_khz;
- set_cyc2ns_scale(cpu_khz);
- /*
- * TSC based sched_clock turns
- * to junk w/ cpufreq
- */
- mark_tsc_unstable("cpufreq changes");
- }
- }
- }
-
- return 0;
-}
-
-static struct notifier_block time_cpufreq_notifier_block = {
- .notifier_call = time_cpufreq_notifier
-};
-
-static int __init cpufreq_tsc(void)
-{
- return cpufreq_register_notifier(&time_cpufreq_notifier_block,
- CPUFREQ_TRANSITION_NOTIFIER);
-}
-core_initcall(cpufreq_tsc);
-
-#endif
-
-/* clock source code */
-
-static unsigned long current_tsc_khz = 0;
-
-static cycle_t read_tsc(void)
-{
- cycle_t ret;
-
- rdtscll(ret);
-
- return ret;
-}
-
-static struct clocksource clocksource_tsc = {
- .name = "tsc",
- .rating = 300,
- .read = read_tsc,
- .mask = CLOCKSOURCE_MASK(64),
- .mult = 0, /* to be set */
- .shift = 22,
- .flags = CLOCK_SOURCE_IS_CONTINUOUS |
- CLOCK_SOURCE_MUST_VERIFY,
-};
-
-void mark_tsc_unstable(char *reason)
-{
- if (!tsc_unstable) {
- tsc_unstable = 1;
- tsc_enabled = 0;
- printk("Marking TSC unstable due to: %s.\n", reason);
- /* Can be called before registration */
- if (clocksource_tsc.mult)
- clocksource_change_rating(&clocksource_tsc, 0);
- else
- clocksource_tsc.rating = 0;
- }
-}
-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);
- tsc_unstable = 1;
- return 0;
-}
-
-/* List of systems that have known TSC problems */
-static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
- {
- .callback = dmi_mark_tsc_unstable,
- .ident = "IBM Thinkpad 380XD",
- .matches = {
- DMI_MATCH(DMI_BOARD_VENDOR, "IBM"),
- DMI_MATCH(DMI_BOARD_NAME, "2635FA0"),
- },
- },
- {}
-};
-
-/*
- * Make an educated guess if the TSC is trustworthy and synchronized
- * over all CPUs.
- */
-__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) {
- /* 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;
-
- 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
-
-
-void __init tsc_init(void)
-{
- if (!cpu_has_tsc || tsc_disable)
- goto out_no_tsc;
-
- cpu_khz = calculate_cpu_khz();
- tsc_khz = cpu_khz;
-
- if (!cpu_khz)
- goto out_no_tsc;
-
- printk("Detected %lu.%03lu MHz processor.\n",
- (unsigned long)cpu_khz / 1000,
- (unsigned long)cpu_khz % 1000);
-
- set_cyc2ns_scale(cpu_khz);
- use_tsc_delay();
-
- /* Check and install the TSC clocksource */
- dmi_check_system(bad_tsc_dmi_table);
-
- 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()) {
- clocksource_tsc.rating = 0;
- clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
- } else
- tsc_enabled = 1;
-
- clocksource_register(&clocksource_tsc);
-
- return;
-
-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;
-}
diff --git a/arch/i386/kernel/tsc_32.c b/arch/i386/kernel/tsc_32.c
new file mode 100644
index 0000000000000..a39280b4dd3a5
--- /dev/null
+++ b/arch/i386/kernel/tsc_32.c
@@ -0,0 +1,413 @@
+/*
+ * This code largely moved from arch/i386/kernel/timer/timer_tsc.c
+ * which was originally moved from arch/i386/kernel/time.c.
+ * See comments there for proper credits.
+ */
+
+#include <linux/sched.h>
+#include <linux/clocksource.h>
+#include <linux/workqueue.h>
+#include <linux/cpufreq.h>
+#include <linux/jiffies.h>
+#include <linux/init.h>
+#include <linux/dmi.h>
+
+#include <asm/delay.h>
+#include <asm/tsc.h>
+#include <asm/io.h>
+#include <asm/timer.h>
+
+#include "mach_timer.h"
+
+static int tsc_enabled;
+
+/*
+ * On some systems the TSC frequency does not
+ * change with the cpu frequency. So we need
+ * an extra value to store the TSC freq
+ */
+unsigned int tsc_khz;
+EXPORT_SYMBOL_GPL(tsc_khz);
+
+int tsc_disable;
+
+#ifdef CONFIG_X86_TSC
+static int __init tsc_setup(char *str)
+{
+ printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
+ "cannot disable TSC.\n");
+ return 1;
+}
+#else
+/*
+ * disable flag for tsc. Takes effect by clearing the TSC cpu flag
+ * in cpu/common.c
+ */
+static int __init tsc_setup(char *str)
+{
+ tsc_disable = 1;
+
+ return 1;
+}
+#endif
+
+__setup("notsc", tsc_setup);
+
+/*
+ * code to mark and check if the TSC is unstable
+ * due to cpufreq or due to unsynced TSCs
+ */
+static int tsc_unstable;
+
+int check_tsc_unstable(void)
+{
+ return tsc_unstable;
+}
+EXPORT_SYMBOL_GPL(check_tsc_unstable);
+
+/* Accellerators 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 percision, 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!"
+ */
+unsigned long cyc2ns_scale __read_mostly;
+
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+
+static inline void set_cyc2ns_scale(unsigned long cpu_khz)
+{
+ cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
+}
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ */
+unsigned long long native_sched_clock(void)
+{
+ unsigned long long this_offset;
+
+ /*
+ * Fall back to jiffies if there's no TSC available:
+ * ( But note that we still use it if the TSC is marked
+ * unstable. We do this because unlike Time Of Day,
+ * the scheduler clock tolerates small errors and it's
+ * very important for it to be as fast as the platform
+ * can achive it. )
+ */
+ if (unlikely(!tsc_enabled && !tsc_unstable))
+ /* No locking but a rare wrong value is not a big deal: */
+ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
+
+ /* read the Time Stamp Counter: */
+ rdtscll(this_offset);
+
+ /* return the value in ns */
+ return cycles_2_ns(this_offset);
+}
+
+/* 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
+
+unsigned long native_calculate_cpu_khz(void)
+{
+ unsigned long long start, end;
+ unsigned long count;
+ u64 delta64;
+ int i;
+ unsigned long flags;
+
+ local_irq_save(flags);
+
+ /* run 3 times to ensure the cache is warm */
+ for (i = 0; i < 3; i++) {
+ mach_prepare_counter();
+ rdtscll(start);
+ mach_countup(&count);
+ rdtscll(end);
+ }
+ /*
+ * Error: ECTCNEVERSET
+ * The CTC wasn't reliable: we got a hit on the very first read,
+ * or the CPU was so fast/slow that the quotient wouldn't fit in
+ * 32 bits..
+ */
+ if (count <= 1)
+ goto err;
+
+ delta64 = end - start;
+
+ /* cpu freq too fast: */
+ if (delta64 > (1ULL<<32))
+ goto err;
+
+ /* cpu freq too slow: */
+ if (delta64 <= CALIBRATE_TIME_MSEC)
+ goto err;
+
+ delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
+ do_div(delta64,CALIBRATE_TIME_MSEC);
+
+ local_irq_restore(flags);
+ return (unsigned long)delta64;
+err:
+ local_irq_restore(flags);
+ return 0;
+}
+
+int recalibrate_cpu_khz(void)
+{
+#ifndef CONFIG_SMP
+ unsigned long cpu_khz_old = cpu_khz;
+
+ if (cpu_has_tsc) {
+ cpu_khz = calculate_cpu_khz();
+ tsc_khz = cpu_khz;
+ cpu_data[0].loops_per_jiffy =
+ cpufreq_scale(cpu_data[0].loops_per_jiffy,
+ cpu_khz_old, cpu_khz);
+ return 0;
+ } else
+ return -ENODEV;
+#else
+ return -ENODEV;
+#endif
+}
+
+EXPORT_SYMBOL(recalibrate_cpu_khz);
+
+#ifdef CONFIG_CPU_FREQ
+
+/*
+ * if the CPU frequency is scaled, TSC-based delays will need a different
+ * loops_per_jiffy value to function properly.
+ */
+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;
+
+ if (!ref_freq) {
+ if (!freq->old){
+ ref_freq = freq->new;
+ return 0;
+ }
+ ref_freq = freq->old;
+ loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
+ cpu_khz_ref = cpu_khz;
+ }
+
+ if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
+ (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
+ (val == CPUFREQ_RESUMECHANGE)) {
+ if (!(freq->flags & CPUFREQ_CONST_LOOPS))
+ cpu_data[freq->cpu].loops_per_jiffy =
+ cpufreq_scale(loops_per_jiffy_ref,
+ ref_freq, freq->new);
+
+ if (cpu_khz) {
+
+ if (num_online_cpus() == 1)
+ cpu_khz = cpufreq_scale(cpu_khz_ref,
+ ref_freq, freq->new);
+ if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
+ tsc_khz = cpu_khz;
+ set_cyc2ns_scale(cpu_khz);
+ /*
+ * TSC based sched_clock turns
+ * to junk w/ cpufreq
+ */
+ mark_tsc_unstable("cpufreq changes");
+ }
+ }
+ }
+
+ return 0;
+}
+
+static struct notifier_block time_cpufreq_notifier_block = {
+ .notifier_call = time_cpufreq_notifier
+};
+
+static int __init cpufreq_tsc(void)
+{
+ return cpufreq_register_notifier(&time_cpufreq_notifier_block,
+ CPUFREQ_TRANSITION_NOTIFIER);
+}
+core_initcall(cpufreq_tsc);
+
+#endif
+
+/* clock source code */
+
+static unsigned long current_tsc_khz = 0;
+
+static cycle_t read_tsc(void)
+{
+ cycle_t ret;
+
+ rdtscll(ret);
+
+ return ret;
+}
+
+static struct clocksource clocksource_tsc = {
+ .name = "tsc",
+ .rating = 300,
+ .read = read_tsc,
+ .mask = CLOCKSOURCE_MASK(64),
+ .mult = 0, /* to be set */
+ .shift = 22,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS |
+ CLOCK_SOURCE_MUST_VERIFY,
+};
+
+void mark_tsc_unstable(char *reason)
+{
+ if (!tsc_unstable) {
+ tsc_unstable = 1;
+ tsc_enabled = 0;
+ printk("Marking TSC unstable due to: %s.\n", reason);
+ /* Can be called before registration */
+ if (clocksource_tsc.mult)
+ clocksource_change_rating(&clocksource_tsc, 0);
+ else
+ clocksource_tsc.rating = 0;
+ }
+}
+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);
+ tsc_unstable = 1;
+ return 0;
+}
+
+/* List of systems that have known TSC problems */
+static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
+ {
+ .callback = dmi_mark_tsc_unstable,
+ .ident = "IBM Thinkpad 380XD",
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "IBM"),
+ DMI_MATCH(DMI_BOARD_NAME, "2635FA0"),
+ },
+ },
+ {}
+};
+
+/*
+ * Make an educated guess if the TSC is trustworthy and synchronized
+ * over all CPUs.
+ */
+__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) {
+ /* 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;
+
+ 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
+
+
+void __init tsc_init(void)
+{
+ if (!cpu_has_tsc || tsc_disable)
+ goto out_no_tsc;
+
+ cpu_khz = calculate_cpu_khz();
+ tsc_khz = cpu_khz;
+
+ if (!cpu_khz)
+ goto out_no_tsc;
+
+ printk("Detected %lu.%03lu MHz processor.\n",
+ (unsigned long)cpu_khz / 1000,
+ (unsigned long)cpu_khz % 1000);
+
+ set_cyc2ns_scale(cpu_khz);
+ use_tsc_delay();
+
+ /* Check and install the TSC clocksource */
+ dmi_check_system(bad_tsc_dmi_table);
+
+ 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()) {
+ clocksource_tsc.rating = 0;
+ clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
+ } else
+ tsc_enabled = 1;
+
+ clocksource_register(&clocksource_tsc);
+
+ return;
+
+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;
+}