diff options
Diffstat (limited to 'arch/x86_64/kernel/time.c')
| -rw-r--r-- | arch/x86_64/kernel/time.c | 64 |
1 files changed, 47 insertions, 17 deletions
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 0e3b60e1ac5..fb8c809b4cd 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -26,6 +26,10 @@ #include <linux/sysdev.h> #include <linux/bcd.h> #include <linux/kallsyms.h> +#include <linux/acpi.h> +#ifdef CONFIG_ACPI +#include <acpi/achware.h> /* for PM timer frequency */ +#endif #include <asm/8253pit.h> #include <asm/pgtable.h> #include <asm/vsyscall.h> @@ -396,6 +400,10 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) (offset - vxtime.last)*(NSEC_PER_SEC/HZ) / hpet_tick; vxtime.last = offset; +#ifdef CONFIG_X86_PM_TIMER + } else if (vxtime.mode == VXTIME_PMTMR) { + lost = pmtimer_mark_offset(); +#endif } else { offset = (((tsc - vxtime.last_tsc) * vxtime.tsc_quot) >> 32) - (USEC_PER_SEC / HZ); @@ -898,6 +906,13 @@ void __init time_init(void) hpet_period; cpu_khz = hpet_calibrate_tsc(); timename = "HPET"; +#ifdef CONFIG_X86_PM_TIMER + } else if (pmtmr_ioport) { + vxtime_hz = PM_TIMER_FREQUENCY; + timename = "PM"; + pit_init(); + cpu_khz = pit_calibrate_tsc(); +#endif } else { pit_init(); cpu_khz = pit_calibrate_tsc(); @@ -923,35 +938,50 @@ void __init time_init(void) } /* + * Make an educated guess if the TSC is trustworthy and synchronized + * over all CPUs. + */ +static __init int unsynchronized_tsc(void) +{ +#ifdef CONFIG_SMP + if (oem_force_hpet_timer()) + return 1; + /* Intel systems are normally all synchronized. Exceptions + are handled in the OEM check above. */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) + return 0; + /* All in a single socket - should be synchronized */ + if (cpus_weight(cpu_core_map[0]) == num_online_cpus()) + return 0; +#endif + /* Assume multi socket systems are not synchronized */ + return num_online_cpus() > 1; +} + +/* * Decide after all CPUs are booted what mode gettimeofday should use. */ void __init time_init_gtod(void) { char *timetype; - /* - * AMD systems with more than one CPU don't have fully synchronized - * TSCs. Always use HPET gettimeofday for these, although it is slower. - * Intel SMP systems usually have synchronized TSCs, so use always - * the TSC. - * - * Exceptions: - * IBM Summit2 checked by oem_force_hpet_timer(). - * AMD dual core may also not need HPET. Check me. - * - * Can be turned off with "notsc". - */ - if (num_online_cpus() > 1 && - boot_cpu_data.x86_vendor == X86_VENDOR_AMD) - notsc = 1; - /* Some systems will want to disable TSC and use HPET. */ - if (oem_force_hpet_timer()) + if (unsynchronized_tsc()) notsc = 1; if (vxtime.hpet_address && notsc) { timetype = "HPET"; vxtime.last = hpet_readl(HPET_T0_CMP) - hpet_tick; vxtime.mode = VXTIME_HPET; do_gettimeoffset = do_gettimeoffset_hpet; +#ifdef CONFIG_X86_PM_TIMER + /* Using PM for gettimeofday is quite slow, but we have no other + choice because the TSC is too unreliable on some systems. */ + } else if (pmtmr_ioport && !vxtime.hpet_address && notsc) { + timetype = "PM"; + do_gettimeoffset = do_gettimeoffset_pm; + vxtime.mode = VXTIME_PMTMR; + sysctl_vsyscall = 0; + printk(KERN_INFO "Disabling vsyscall due to use of PM timer\n"); +#endif } else { timetype = vxtime.hpet_address ? "HPET/TSC" : "PIT/TSC"; vxtime.mode = VXTIME_TSC; |