x86: merge tsc_init and clocksource code
Unify the clocksource code. Unify the tsc_init code. Signed-off-by: Alok N Kataria <akataria@vmware.com> Signed-off-by: Dan Hecht <dhecht@vmware.com> Cc: Dan Hecht <dhecht@vmware.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alok Kataria
committed by
Ingo Molnar
Ingo Molnar
parent
2dbe06faf3
commit
8fbbc4b45c
@ -5,8 +5,16 @@
|
||||
#include <linux/timer.h>
|
||||
#include <linux/acpi_pmtmr.h>
|
||||
#include <linux/cpufreq.h>
|
||||
#include <linux/dmi.h>
|
||||
#include <linux/delay.h>
|
||||
#include <linux/clocksource.h>
|
||||
#include <linux/percpu.h>
|
||||
|
||||
#include <asm/hpet.h>
|
||||
#include <asm/timer.h>
|
||||
#include <asm/vgtod.h>
|
||||
#include <asm/time.h>
|
||||
#include <asm/delay.h>
|
||||
|
||||
unsigned int cpu_khz; /* TSC clocks / usec, not used here */
|
||||
EXPORT_SYMBOL(cpu_khz);
|
||||
@ -16,12 +24,12 @@ EXPORT_SYMBOL(tsc_khz);
|
||||
/*
|
||||
* TSC can be unstable due to cpufreq or due to unsynced TSCs
|
||||
*/
|
||||
int tsc_unstable;
|
||||
static int tsc_unstable;
|
||||
|
||||
/* native_sched_clock() is called before tsc_init(), so
|
||||
we must start with the TSC soft disabled to prevent
|
||||
erroneous rdtsc usage on !cpu_has_tsc processors */
|
||||
int tsc_disabled = -1;
|
||||
static int tsc_disabled = -1;
|
||||
|
||||
/*
|
||||
* Scheduler clock - returns current time in nanosec units.
|
||||
@ -241,7 +249,7 @@ EXPORT_SYMBOL(recalibrate_cpu_khz);
|
||||
|
||||
DEFINE_PER_CPU(unsigned long, cyc2ns);
|
||||
|
||||
void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
|
||||
static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
|
||||
{
|
||||
unsigned long long tsc_now, ns_now;
|
||||
unsigned long flags, *scale;
|
||||
@ -329,3 +337,201 @@ static int __init cpufreq_tsc(void)
|
||||
core_initcall(cpufreq_tsc);
|
||||
|
||||
#endif /* CONFIG_CPU_FREQ */
|
||||
|
||||
/* clocksource code */
|
||||
|
||||
static struct clocksource clocksource_tsc;
|
||||
|
||||
/*
|
||||
* We compare the TSC to the cycle_last value in the clocksource
|
||||
* structure to avoid a nasty time-warp. This can be observed in a
|
||||
* very small window right after one CPU updated cycle_last under
|
||||
* xtime/vsyscall_gtod lock and the other CPU reads a TSC value which
|
||||
* is smaller than the cycle_last reference value due to a TSC which
|
||||
* is slighty behind. This delta is nowhere else observable, but in
|
||||
* that case it results in a forward time jump in the range of hours
|
||||
* due to the unsigned delta calculation of the time keeping core
|
||||
* code, which is necessary to support wrapping clocksources like pm
|
||||
* timer.
|
||||
*/
|
||||
static cycle_t read_tsc(void)
|
||||
{
|
||||
cycle_t ret = (cycle_t)get_cycles();
|
||||
|
||||
return ret >= clocksource_tsc.cycle_last ?
|
||||
ret : clocksource_tsc.cycle_last;
|
||||
}
|
||||
|
||||
static cycle_t __vsyscall_fn vread_tsc(void)
|
||||
{
|
||||
cycle_t ret = (cycle_t)vget_cycles();
|
||||
|
||||
return ret >= __vsyscall_gtod_data.clock.cycle_last ?
|
||||
ret : __vsyscall_gtod_data.clock.cycle_last;
|
||||
}
|
||||
|
||||
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,
|
||||
#ifdef CONFIG_X86_64
|
||||
.vread = vread_tsc,
|
||||
#endif
|
||||
};
|
||||
|
||||
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);
|
||||
|
||||
static int __init dmi_mark_tsc_unstable(const 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"),
|
||||
},
|
||||
},
|
||||
{}
|
||||
};
|
||||
|
||||
/*
|
||||
* 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 res_low, res_high;
|
||||
|
||||
rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
|
||||
if (res_low & RTSC_SUSP)
|
||||
clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
|
||||
}
|
||||
#else
|
||||
static inline void check_geode_tsc_reliable(void) { }
|
||||
#endif
|
||||
|
||||
/*
|
||||
* 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;
|
||||
|
||||
#ifdef CONFIG_SMP
|
||||
if (apic_is_clustered_box())
|
||||
return 1;
|
||||
#endif
|
||||
|
||||
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
|
||||
return 0;
|
||||
/*
|
||||
* 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;
|
||||
}
|
||||
|
||||
static void __init init_tsc_clocksource(void)
|
||||
{
|
||||
clocksource_tsc.mult = clocksource_khz2mult(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;
|
||||
}
|
||||
clocksource_register(&clocksource_tsc);
|
||||
}
|
||||
|
||||
void __init tsc_init(void)
|
||||
{
|
||||
u64 lpj;
|
||||
int cpu;
|
||||
|
||||
if (!cpu_has_tsc)
|
||||
return;
|
||||
|
||||
cpu_khz = calculate_cpu_khz();
|
||||
tsc_khz = cpu_khz;
|
||||
|
||||
if (!cpu_khz) {
|
||||
mark_tsc_unstable("could not calculate TSC khz");
|
||||
return;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_X86_64
|
||||
if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
|
||||
(boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
|
||||
cpu_khz = calibrate_cpu();
|
||||
#endif
|
||||
|
||||
lpj = ((u64)tsc_khz * 1000);
|
||||
do_div(lpj, HZ);
|
||||
lpj_fine = lpj;
|
||||
|
||||
printk("Detected %lu.%03lu MHz processor.\n",
|
||||
(unsigned long)cpu_khz / 1000,
|
||||
(unsigned long)cpu_khz % 1000);
|
||||
|
||||
/*
|
||||
* Secondary CPUs do not run through tsc_init(), so set up
|
||||
* all the scale factors for all CPUs, assuming the same
|
||||
* speed as the bootup CPU. (cpufreq notifiers will fix this
|
||||
* up if their speed diverges)
|
||||
*/
|
||||
for_each_possible_cpu(cpu)
|
||||
set_cyc2ns_scale(cpu_khz, cpu);
|
||||
|
||||
if (tsc_disabled > 0)
|
||||
return;
|
||||
|
||||
/* now allow native_sched_clock() to use rdtsc */
|
||||
tsc_disabled = 0;
|
||||
|
||||
use_tsc_delay();
|
||||
/* Check and install the TSC clocksource */
|
||||
dmi_check_system(bad_tsc_dmi_table);
|
||||
|
||||
if (unsynchronized_tsc())
|
||||
mark_tsc_unstable("TSCs unsynchronized");
|
||||
|
||||
check_geode_tsc_reliable();
|
||||
init_tsc_clocksource();
|
||||
}
|
||||
|
||||
|
||||
Reference in New Issue
Block a user