diff options
Diffstat (limited to 'arch/ia64/kernel/time.c')
| -rw-r--r-- | arch/ia64/kernel/time.c | 112 |
1 files changed, 103 insertions, 9 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index 3486fe7d6e6..98cfc90cab1 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c @@ -19,6 +19,7 @@ #include <linux/interrupt.h> #include <linux/efi.h> #include <linux/timex.h> +#include <linux/clocksource.h> #include <asm/machvec.h> #include <asm/delay.h> @@ -28,6 +29,16 @@ #include <asm/sections.h> #include <asm/system.h> +#include "fsyscall_gtod_data.h" + +static cycle_t itc_get_cycles(void); + +struct fsyscall_gtod_data_t fsyscall_gtod_data = { + .lock = SEQLOCK_UNLOCKED, +}; + +struct itc_jitter_data_t itc_jitter_data; + volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */ #ifdef CONFIG_IA64_DEBUG_IRQ @@ -37,11 +48,16 @@ EXPORT_SYMBOL(last_cli_ip); #endif -static struct time_interpolator itc_interpolator = { - .shift = 16, - .mask = 0xffffffffffffffffLL, - .source = TIME_SOURCE_CPU +static struct clocksource clocksource_itc = { + .name = "itc", + .rating = 350, + .read = itc_get_cycles, + .mask = CLOCKSOURCE_MASK(64), + .mult = 0, /*to be caluclated*/ + .shift = 16, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static struct clocksource *itc_clocksource; static irqreturn_t timer_interrupt (int irq, void *dev_id) @@ -210,8 +226,6 @@ ia64_init_itm (void) + itc_freq/2)/itc_freq; if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) { - itc_interpolator.frequency = local_cpu_data->itc_freq; - itc_interpolator.drift = itc_drift; #ifdef CONFIG_SMP /* On IA64 in an SMP configuration ITCs are never accurately synchronized. * Jitter compensation requires a cmpxchg which may limit @@ -223,15 +237,64 @@ ia64_init_itm (void) * even going backward) if the ITC offsets between the individual CPUs * are too large. */ - if (!nojitter) itc_interpolator.jitter = 1; + if (!nojitter) + itc_jitter_data.itc_jitter = 1; #endif - register_time_interpolator(&itc_interpolator); - } + } else + /* + * ITC is drifty and we have not synchronized the ITCs in smpboot.c. + * ITC values may fluctuate significantly between processors. + * Clock should not be used for hrtimers. Mark itc as only + * useful for boot and testing. + * + * Note that jitter compensation is off! There is no point of + * synchronizing ITCs since they may be large differentials + * that change over time. + * + * The only way to fix this would be to repeatedly sync the + * ITCs. Until that time we have to avoid ITC. + */ + clocksource_itc.rating = 50; /* Setup the CPU local timer tick */ ia64_cpu_local_tick(); + + if (!itc_clocksource) { + /* Sort out mult/shift values: */ + clocksource_itc.mult = + clocksource_hz2mult(local_cpu_data->itc_freq, + clocksource_itc.shift); + clocksource_register(&clocksource_itc); + itc_clocksource = &clocksource_itc; + } +} + +static cycle_t itc_get_cycles(void) +{ + u64 lcycle, now, ret; + + if (!itc_jitter_data.itc_jitter) + return get_cycles(); + + lcycle = itc_jitter_data.itc_lastcycle; + now = get_cycles(); + if (lcycle && time_after(lcycle, now)) + return lcycle; + + /* + * Keep track of the last timer value returned. + * In an SMP environment, you could lose out in contention of + * cmpxchg. If so, your cmpxchg returns new value which the + * winner of contention updated to. Use the new value instead. + */ + ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now); + if (unlikely(ret != lcycle)) + return ret; + + return now; } + static struct irqaction timer_irqaction = { .handler = timer_interrupt, .flags = IRQF_DISABLED | IRQF_IRQPOLL, @@ -307,3 +370,34 @@ ia64_setup_printk_clock(void) if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) ia64_printk_clock = ia64_itc_printk_clock; } + +void update_vsyscall(struct timespec *wall, struct clocksource *c) +{ + unsigned long flags; + + write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags); + + /* copy fsyscall clock data */ + fsyscall_gtod_data.clk_mask = c->mask; + fsyscall_gtod_data.clk_mult = c->mult; + fsyscall_gtod_data.clk_shift = c->shift; + fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio; + fsyscall_gtod_data.clk_cycle_last = c->cycle_last; + + /* copy kernel time structures */ + fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec; + fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec; + fsyscall_gtod_data.monotonic_time.tv_sec = wall_to_monotonic.tv_sec + + wall->tv_sec; + fsyscall_gtod_data.monotonic_time.tv_nsec = wall_to_monotonic.tv_nsec + + wall->tv_nsec; + + /* normalize */ + while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) { + fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC; + fsyscall_gtod_data.monotonic_time.tv_sec++; + } + + write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags); +} + |