diff options
| author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2009-04-07 05:51:29 +0400 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2009-04-08 02:17:51 +0400 |
| commit | db954b5898dd3ef3ef93f4144158ea8f97deb058 (patch) | |
| tree | 781b62baa5aa262fca99198ba326e5e9cc44b26a | |
| parent | 577c9c456f0e1371cbade38eaf91ae8e8a308555 (diff) | |
| download | linux-db954b5898dd3ef3ef93f4144158ea8f97deb058.tar.xz | |
x86 ACPI: Add support for Always Running APIC timer
Add support for Always Running APIC timer, CPUID_0x6_EAX_Bit2.
This bit means the APIC timer continues to run even when CPU is
in deep C-states.
The advantage is that we can use LAPIC timer on these CPUs
always, and there is no need for "slow to read and program"
external timers (HPET/PIT) and the timer broadcast logic
and related code in C-state entry and exit.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Len Brown <len.brown@intel.com>
| -rw-r--r-- | arch/x86/include/asm/cpufeature.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/addon_cpuid_features.c | 1 | ||||
| -rw-r--r-- | drivers/acpi/processor_idle.c | 3 |
4 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 0beba0d1468d..bb83b1c397aa 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -154,6 +154,7 @@ * CPUID levels like 0x6, 0xA etc */ #define X86_FEATURE_IDA (7*32+ 0) /* Intel Dynamic Acceleration */ +#define X86_FEATURE_ARAT (7*32+ 1) /* Always Running APIC Timer */ /* Virtualization flags: Linux defined */ #define X86_FEATURE_TPR_SHADOW (8*32+ 0) /* Intel TPR Shadow */ diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 098ec84b8c00..f2870920f246 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -431,6 +431,12 @@ static void __cpuinit setup_APIC_timer(void) { struct clock_event_device *levt = &__get_cpu_var(lapic_events); + if (cpu_has(¤t_cpu_data, X86_FEATURE_ARAT)) { + lapic_clockevent.features &= ~CLOCK_EVT_FEAT_C3STOP; + /* Make LAPIC timer preferrable over percpu HPET */ + lapic_clockevent.rating = 150; + } + memcpy(levt, &lapic_clockevent, sizeof(*levt)); levt->cpumask = cpumask_of(smp_processor_id()); diff --git a/arch/x86/kernel/cpu/addon_cpuid_features.c b/arch/x86/kernel/cpu/addon_cpuid_features.c index 8220ae69849d..c965e5212714 100644 --- a/arch/x86/kernel/cpu/addon_cpuid_features.c +++ b/arch/x86/kernel/cpu/addon_cpuid_features.c @@ -31,6 +31,7 @@ void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c) static const struct cpuid_bit __cpuinitconst cpuid_bits[] = { { X86_FEATURE_IDA, CR_EAX, 1, 0x00000006 }, + { X86_FEATURE_ARAT, CR_EAX, 2, 0x00000006 }, { 0, 0, 0, 0 } }; diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 4e6e758bd397..6fe121434ffb 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -145,6 +145,9 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr, struct acpi_processor_power *pwr = &pr->power; u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2; + if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT)) + return; + /* * Check, if one of the previous states already marked the lapic * unstable |