diff options
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r-- | arch/powerpc/kernel/time.c | 541 |
1 files changed, 201 insertions, 340 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 0441bbdadbd1..010406958d97 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -53,7 +53,7 @@ #include <linux/posix-timers.h> #include <linux/irq.h> #include <linux/delay.h> -#include <linux/perf_event.h> +#include <linux/irq_work.h> #include <asm/trace.h> #include <asm/io.h> @@ -149,16 +149,6 @@ unsigned long tb_ticks_per_usec = 100; /* sane default */ EXPORT_SYMBOL(tb_ticks_per_usec); unsigned long tb_ticks_per_sec; EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */ -u64 tb_to_xs; -unsigned tb_to_us; - -#define TICKLEN_SCALE NTP_SCALE_SHIFT -static u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */ -static u64 ticklen_to_xs; /* 0.64 fraction */ - -/* If last_tick_len corresponds to about 1/HZ seconds, then - last_tick_len << TICKLEN_SHIFT will be about 2^63. */ -#define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ) DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL_GPL(rtc_lock); @@ -171,11 +161,9 @@ extern struct timezone sys_tz; static long timezone_offset; unsigned long ppc_proc_freq; -EXPORT_SYMBOL(ppc_proc_freq); +EXPORT_SYMBOL_GPL(ppc_proc_freq); unsigned long ppc_tb_freq; - -static u64 tb_last_jiffy __cacheline_aligned_in_smp; -static DEFINE_PER_CPU(u64, last_jiffy); +EXPORT_SYMBOL_GPL(ppc_tb_freq); #ifdef CONFIG_VIRT_CPU_ACCOUNTING /* @@ -196,6 +184,8 @@ DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta); cputime_t cputime_one_jiffy; +void (*dtl_consumer)(struct dtl_entry *, u64); + static void calc_cputime_factors(void) { struct div_result res; @@ -211,62 +201,153 @@ static void calc_cputime_factors(void) } /* - * Read the PURR on systems that have it, otherwise the timebase. + * Read the SPURR on systems that have it, otherwise the PURR, + * or if that doesn't exist return the timebase value passed in. */ -static u64 read_purr(void) +static u64 read_spurr(u64 tb) { + if (cpu_has_feature(CPU_FTR_SPURR)) + return mfspr(SPRN_SPURR); if (cpu_has_feature(CPU_FTR_PURR)) return mfspr(SPRN_PURR); - return mftb(); + return tb; } +#ifdef CONFIG_PPC_SPLPAR + /* - * Read the SPURR on systems that have it, otherwise the purr + * Scan the dispatch trace log and count up the stolen time. + * Should be called with interrupts disabled. */ -static u64 read_spurr(u64 purr) +static u64 scan_dispatch_log(u64 stop_tb) { - /* - * cpus without PURR won't have a SPURR - * We already know the former when we use this, so tell gcc - */ - if (cpu_has_feature(CPU_FTR_PURR) && cpu_has_feature(CPU_FTR_SPURR)) - return mfspr(SPRN_SPURR); - return purr; + u64 i = local_paca->dtl_ridx; + struct dtl_entry *dtl = local_paca->dtl_curr; + struct dtl_entry *dtl_end = local_paca->dispatch_log_end; + struct lppaca *vpa = local_paca->lppaca_ptr; + u64 tb_delta; + u64 stolen = 0; + u64 dtb; + + if (i == vpa->dtl_idx) + return 0; + while (i < vpa->dtl_idx) { + if (dtl_consumer) + dtl_consumer(dtl, i); + dtb = dtl->timebase; + tb_delta = dtl->enqueue_to_dispatch_time + + dtl->ready_to_enqueue_time; + barrier(); + if (i + N_DISPATCH_LOG < vpa->dtl_idx) { + /* buffer has overflowed */ + i = vpa->dtl_idx - N_DISPATCH_LOG; + dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG); + continue; + } + if (dtb > stop_tb) + break; + stolen += tb_delta; + ++i; + ++dtl; + if (dtl == dtl_end) + dtl = local_paca->dispatch_log; + } + local_paca->dtl_ridx = i; + local_paca->dtl_curr = dtl; + return stolen; +} + +/* + * Accumulate stolen time by scanning the dispatch trace log. + * Called on entry from user mode. + */ +void accumulate_stolen_time(void) +{ + u64 sst, ust; + + sst = scan_dispatch_log(get_paca()->starttime_user); + ust = scan_dispatch_log(get_paca()->starttime); + get_paca()->system_time -= sst; + get_paca()->user_time -= ust; + get_paca()->stolen_time += ust + sst; +} + +static inline u64 calculate_stolen_time(u64 stop_tb) +{ + u64 stolen = 0; + + if (get_paca()->dtl_ridx != get_paca()->lppaca_ptr->dtl_idx) { + stolen = scan_dispatch_log(stop_tb); + get_paca()->system_time -= stolen; + } + + stolen += get_paca()->stolen_time; + get_paca()->stolen_time = 0; + return stolen; } +#else /* CONFIG_PPC_SPLPAR */ +static inline u64 calculate_stolen_time(u64 stop_tb) +{ + return 0; +} + +#endif /* CONFIG_PPC_SPLPAR */ + /* * Account time for a transition between system, hard irq * or soft irq state. */ void account_system_vtime(struct task_struct *tsk) { - u64 now, nowscaled, delta, deltascaled, sys_time; + u64 now, nowscaled, delta, deltascaled; unsigned long flags; + u64 stolen, udelta, sys_scaled, user_scaled; local_irq_save(flags); - now = read_purr(); + now = mftb(); nowscaled = read_spurr(now); - delta = now - get_paca()->startpurr; + get_paca()->system_time += now - get_paca()->starttime; + get_paca()->starttime = now; deltascaled = nowscaled - get_paca()->startspurr; - get_paca()->startpurr = now; get_paca()->startspurr = nowscaled; - if (!in_interrupt()) { - /* deltascaled includes both user and system time. - * Hence scale it based on the purr ratio to estimate - * the system time */ - sys_time = get_paca()->system_time; - if (get_paca()->user_time) - deltascaled = deltascaled * sys_time / - (sys_time + get_paca()->user_time); - delta += sys_time; - get_paca()->system_time = 0; + + stolen = calculate_stolen_time(now); + + delta = get_paca()->system_time; + get_paca()->system_time = 0; + udelta = get_paca()->user_time - get_paca()->utime_sspurr; + get_paca()->utime_sspurr = get_paca()->user_time; + + /* + * Because we don't read the SPURR on every kernel entry/exit, + * deltascaled includes both user and system SPURR ticks. + * Apportion these ticks to system SPURR ticks and user + * SPURR ticks in the same ratio as the system time (delta) + * and user time (udelta) values obtained from the timebase + * over the same interval. The system ticks get accounted here; + * the user ticks get saved up in paca->user_time_scaled to be + * used by account_process_tick. + */ + sys_scaled = delta; + user_scaled = udelta; + if (deltascaled != delta + udelta) { + if (udelta) { + sys_scaled = deltascaled * delta / (delta + udelta); + user_scaled = deltascaled - sys_scaled; + } else { + sys_scaled = deltascaled; + } + } + get_paca()->user_time_scaled += user_scaled; + + if (in_irq() || idle_task(smp_processor_id()) != tsk) { + account_system_time(tsk, 0, delta, sys_scaled); + if (stolen) + account_steal_time(stolen); + } else { + account_idle_time(delta + stolen); } - if (in_irq() || idle_task(smp_processor_id()) != tsk) - account_system_time(tsk, 0, delta, deltascaled); - else - account_idle_time(delta); - __get_cpu_var(cputime_last_delta) = delta; - __get_cpu_var(cputime_scaled_last_delta) = deltascaled; local_irq_restore(flags); } EXPORT_SYMBOL_GPL(account_system_vtime); @@ -276,125 +357,26 @@ EXPORT_SYMBOL_GPL(account_system_vtime); * by the exception entry and exit code to the generic process * user and system time records. * Must be called with interrupts disabled. + * Assumes that account_system_vtime() has been called recently + * (i.e. since the last entry from usermode) so that + * get_paca()->user_time_scaled is up to date. */ void account_process_tick(struct task_struct *tsk, int user_tick) { cputime_t utime, utimescaled; utime = get_paca()->user_time; + utimescaled = get_paca()->user_time_scaled; get_paca()->user_time = 0; - utimescaled = cputime_to_scaled(utime); + get_paca()->user_time_scaled = 0; + get_paca()->utime_sspurr = 0; account_user_time(tsk, utime, utimescaled); } -/* - * Stuff for accounting stolen time. - */ -struct cpu_purr_data { - int initialized; /* thread is running */ - u64 tb; /* last TB value read */ - u64 purr; /* last PURR value read */ - u64 spurr; /* last SPURR value read */ -}; - -/* - * Each entry in the cpu_purr_data array is manipulated only by its - * "owner" cpu -- usually in the timer interrupt but also occasionally - * in process context for cpu online. As long as cpus do not touch - * each others' cpu_purr_data, disabling local interrupts is - * sufficient to serialize accesses. - */ -static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data); - -static void snapshot_tb_and_purr(void *data) -{ - unsigned long flags; - struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data); - - local_irq_save(flags); - p->tb = get_tb_or_rtc(); - p->purr = mfspr(SPRN_PURR); - wmb(); - p->initialized = 1; - local_irq_restore(flags); -} - -/* - * Called during boot when all cpus have come up. - */ -void snapshot_timebases(void) -{ - if (!cpu_has_feature(CPU_FTR_PURR)) - return; - on_each_cpu(snapshot_tb_and_purr, NULL, 1); -} - -/* - * Must be called with interrupts disabled. - */ -void calculate_steal_time(void) -{ - u64 tb, purr; - s64 stolen; - struct cpu_purr_data *pme; - - pme = &__get_cpu_var(cpu_purr_data); - if (!pme->initialized) - return; /* !CPU_FTR_PURR or early in early boot */ - tb = mftb(); - purr = mfspr(SPRN_PURR); - stolen = (tb - pme->tb) - (purr - pme->purr); - if (stolen > 0) { - if (idle_task(smp_processor_id()) != current) - account_steal_time(stolen); - else - account_idle_time(stolen); - } - pme->tb = tb; - pme->purr = purr; -} - -#ifdef CONFIG_PPC_SPLPAR -/* - * Must be called before the cpu is added to the online map when - * a cpu is being brought up at runtime. - */ -static void snapshot_purr(void) -{ - struct cpu_purr_data *pme; - unsigned long flags; - - if (!cpu_has_feature(CPU_FTR_PURR)) - return; - local_irq_save(flags); - pme = &__get_cpu_var(cpu_purr_data); - pme->tb = mftb(); - pme->purr = mfspr(SPRN_PURR); - pme->initialized = 1; - local_irq_restore(flags); -} - -#endif /* CONFIG_PPC_SPLPAR */ - #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */ #define calc_cputime_factors() -#define calculate_steal_time() do { } while (0) #endif -#if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR)) -#define snapshot_purr() do { } while (0) -#endif - -/* - * Called when a cpu comes up after the system has finished booting, - * i.e. as a result of a hotplug cpu action. - */ -void snapshot_timebase(void) -{ - __get_cpu_var(last_jiffy) = get_tb_or_rtc(); - snapshot_purr(); -} - void __delay(unsigned long loops) { unsigned long start; @@ -423,30 +405,6 @@ void udelay(unsigned long usecs) } EXPORT_SYMBOL(udelay); -static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec, - u64 new_tb_to_xs) -{ - /* - * tb_update_count is used to allow the userspace gettimeofday code - * to assure itself that it sees a consistent view of the tb_to_xs and - * stamp_xsec variables. It reads the tb_update_count, then reads - * tb_to_xs and stamp_xsec and then reads tb_update_count again. If - * the two values of tb_update_count match and are even then the - * tb_to_xs and stamp_xsec values are consistent. If not, then it - * loops back and reads them again until this criteria is met. - * We expect the caller to have done the first increment of - * vdso_data->tb_update_count already. - */ - vdso_data->tb_orig_stamp = new_tb_stamp; - vdso_data->stamp_xsec = new_stamp_xsec; - vdso_data->tb_to_xs = new_tb_to_xs; - vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec; - vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec; - vdso_data->stamp_xtime = xtime; - smp_wmb(); - ++(vdso_data->tb_update_count); -} - #ifdef CONFIG_SMP unsigned long profile_pc(struct pt_regs *regs) { @@ -470,7 +428,6 @@ EXPORT_SYMBOL(profile_pc); static int __init iSeries_tb_recal(void) { - struct div_result divres; unsigned long titan, tb; /* Make sure we only run on iSeries */ @@ -501,10 +458,7 @@ static int __init iSeries_tb_recal(void) tb_ticks_per_jiffy = new_tb_ticks_per_jiffy; tb_ticks_per_sec = new_tb_ticks_per_sec; calc_cputime_factors(); - div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres ); - tb_to_xs = divres.result_low; vdso_data->tb_ticks_per_sec = tb_ticks_per_sec; - vdso_data->tb_to_xs = tb_to_xs; setup_cputime_one_jiffy(); } else { @@ -532,60 +486,60 @@ void __init iSeries_time_init_early(void) } #endif /* CONFIG_PPC_ISERIES */ -#ifdef CONFIG_PERF_EVENTS +#ifdef CONFIG_IRQ_WORK /* * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable... */ #ifdef CONFIG_PPC64 -static inline unsigned long test_perf_event_pending(void) +static inline unsigned long test_irq_work_pending(void) { unsigned long x; asm volatile("lbz %0,%1(13)" : "=r" (x) - : "i" (offsetof(struct paca_struct, perf_event_pending))); + : "i" (offsetof(struct paca_struct, irq_work_pending))); return x; } -static inline void set_perf_event_pending_flag(void) +static inline void set_irq_work_pending_flag(void) { asm volatile("stb %0,%1(13)" : : "r" (1), - "i" (offsetof(struct paca_struct, perf_event_pending))); + "i" (offsetof(struct paca_struct, irq_work_pending))); } -static inline void clear_perf_event_pending(void) +static inline void clear_irq_work_pending(void) { asm volatile("stb %0,%1(13)" : : "r" (0), - "i" (offsetof(struct paca_struct, perf_event_pending))); + "i" (offsetof(struct paca_struct, irq_work_pending))); } #else /* 32-bit */ -DEFINE_PER_CPU(u8, perf_event_pending); +DEFINE_PER_CPU(u8, irq_work_pending); -#define set_perf_event_pending_flag() __get_cpu_var(perf_event_pending) = 1 -#define test_perf_event_pending() __get_cpu_var(perf_event_pending) -#define clear_perf_event_pending() __get_cpu_var(perf_event_pending) = 0 +#define set_irq_work_pending_flag() __get_cpu_var(irq_work_pending) = 1 +#define test_irq_work_pending() __get_cpu_var(irq_work_pending) +#define clear_irq_work_pending() __get_cpu_var(irq_work_pending) = 0 #endif /* 32 vs 64 bit */ -void set_perf_event_pending(void) +void set_irq_work_pending(void) { preempt_disable(); - set_perf_event_pending_flag(); + set_irq_work_pending_flag(); set_dec(1); preempt_enable(); } -#else /* CONFIG_PERF_EVENTS */ +#else /* CONFIG_IRQ_WORK */ -#define test_perf_event_pending() 0 -#define clear_perf_event_pending() +#define test_irq_work_pending() 0 +#define clear_irq_work_pending() -#endif /* CONFIG_PERF_EVENTS */ +#endif /* CONFIG_IRQ_WORK */ /* * For iSeries shared processors, we have to let the hypervisor @@ -616,28 +570,17 @@ void timer_interrupt(struct pt_regs * regs) * some CPUs will continuue to take decrementer exceptions */ set_dec(DECREMENTER_MAX); -#ifdef CONFIG_PPC32 +#if defined(CONFIG_PPC32) && defined(CONFIG_PMAC) if (atomic_read(&ppc_n_lost_interrupts) != 0) do_IRQ(regs); #endif - now = get_tb_or_rtc(); - if (now < decrementer->next_tb) { - /* not time for this event yet */ - now = decrementer->next_tb - now; - if (now <= DECREMENTER_MAX) - set_dec((int)now); - trace_timer_interrupt_exit(regs); - return; - } old_regs = set_irq_regs(regs); irq_enter(); - calculate_steal_time(); - - if (test_perf_event_pending()) { - clear_perf_event_pending(); - perf_event_do_pending(); + if (test_irq_work_pending()) { + clear_irq_work_pending(); + irq_work_run(); } #ifdef CONFIG_PPC_ISERIES @@ -645,8 +588,16 @@ void timer_interrupt(struct pt_regs * regs) get_lppaca()->int_dword.fields.decr_int = 0; #endif - if (evt->event_handler) - evt->event_handler(evt); + now = get_tb_or_rtc(); + if (now >= decrementer->next_tb) { + decrementer->next_tb = ~(u64)0; + if (evt->event_handler) + evt->event_handler(evt); + } else { + now = decrementer->next_tb - now; + if (now <= DECREMENTER_MAX) + set_dec((int)now); + } #ifdef CONFIG_PPC_ISERIES if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending()) @@ -667,27 +618,9 @@ void timer_interrupt(struct pt_regs * regs) trace_timer_interrupt_exit(regs); } -void wakeup_decrementer(void) -{ - unsigned long ticks; - - /* - * The timebase gets saved on sleep and restored on wakeup, - * so all we need to do is to reset the decrementer. - */ - ticks = tb_ticks_since(__get_cpu_var(last_jiffy)); - if (ticks < tb_ticks_per_jiffy) - ticks = tb_ticks_per_jiffy - ticks; - else - ticks = 1; - set_dec(ticks); -} - #ifdef CONFIG_SUSPEND -void generic_suspend_disable_irqs(void) +static void generic_suspend_disable_irqs(void) { - preempt_disable(); - /* Disable the decrementer, so that it doesn't interfere * with suspending. */ @@ -697,12 +630,9 @@ void generic_suspend_disable_irqs(void) set_dec(0x7fffffff); } -void generic_suspend_enable_irqs(void) +static void generic_suspend_enable_irqs(void) { - wakeup_decrementer(); - local_irq_enable(); - preempt_enable(); } /* Overrides the weak version in kernel/power/main.c */ @@ -722,23 +652,6 @@ void arch_suspend_enable_irqs(void) } #endif -#ifdef CONFIG_SMP -void __init smp_space_timers(unsigned int max_cpus) -{ - int i; - u64 previous_tb = per_cpu(last_jiffy, boot_cpuid); - - /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */ - previous_tb -= tb_ticks_per_jiffy; - - for_each_possible_cpu(i) { - if (i == boot_cpuid) - continue; - per_cpu(last_jiffy, i) = previous_tb; - } -} -#endif - /* * Scheduler clock - returns current time in nanosec units. * @@ -873,10 +786,11 @@ static cycle_t timebase_read(struct clocksource *cs) return (cycle_t)get_tb(); } -void update_vsyscall(struct timespec *wall_time, struct clocksource *clock, - u32 mult) +void update_vsyscall(struct timespec *wall_time, struct timespec *wtm, + struct clocksource *clock, u32 mult) { - u64 t2x, stamp_xsec; + u64 new_tb_to_xs, new_stamp_xsec; + u32 frac_sec; if (clock != &clocksource_timebase) return; @@ -887,11 +801,35 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock, /* XXX this assumes clock->shift == 22 */ /* 4611686018 ~= 2^(20+64-22) / 1e9 */ - t2x = (u64) mult * 4611686018ULL; - stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC; - do_div(stamp_xsec, 1000000000); - stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC; - update_gtod(clock->cycle_last, stamp_xsec, t2x); + new_tb_to_xs = (u64) mult * 4611686018ULL; + new_stamp_xsec = (u64) wall_time->tv_nsec * XSEC_PER_SEC; + do_div(new_stamp_xsec, 1000000000); + new_stamp_xsec += (u64) wall_time->tv_sec * XSEC_PER_SEC; + + BUG_ON(wall_time->tv_nsec >= NSEC_PER_SEC); + /* this is tv_nsec / 1e9 as a 0.32 fraction */ + frac_sec = ((u64) wall_time->tv_nsec * 18446744073ULL) >> 32; + + /* + * tb_update_count is used to allow the userspace gettimeofday code + * to assure itself that it sees a consistent view of the tb_to_xs and + * stamp_xsec variables. It reads the tb_update_count, then reads + * tb_to_xs and stamp_xsec and then reads tb_update_count again. If + * the two values of tb_update_count match and are even then the + * tb_to_xs and stamp_xsec values are consistent. If not, then it + * loops back and reads them again until this criteria is met. + * We expect the caller to have done the first increment of + * vdso_data->tb_update_count already. + */ + vdso_data->tb_orig_stamp = clock->cycle_last; + vdso_data->stamp_xsec = new_stamp_xsec; + vdso_data->tb_to_xs = new_tb_to_xs; + vdso_data->wtom_clock_sec = wtm->tv_sec; + vdso_data->wtom_clock_nsec = wtm->tv_nsec; + vdso_data->stamp_xtime = *wall_time; + vdso_data->stamp_sec_fraction = frac_sec; + smp_wmb(); + ++(vdso_data->tb_update_count); } void update_vsyscall_tz(void) @@ -1007,15 +945,13 @@ void secondary_cpu_time_init(void) /* This function is only called on the boot processor */ void __init time_init(void) { - unsigned long flags; struct div_result res; - u64 scale, x; + u64 scale; unsigned shift; if (__USE_RTC()) { /* 601 processor: dec counts down by 128 every 128ns */ ppc_tb_freq = 1000000000; - tb_last_jiffy = get_rtcl(); } else { /* Normal PowerPC with timebase register */ ppc_md.calibrate_decr(); @@ -1023,50 +959,15 @@ void __init time_init(void) ppc_tb_freq / 1000000, ppc_tb_freq % 1000000); printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n", ppc_proc_freq / 1000000, ppc_proc_freq % 1000000); - tb_last_jiffy = get_tb(); } tb_ticks_per_jiffy = ppc_tb_freq / HZ; tb_ticks_per_sec = ppc_tb_freq; tb_ticks_per_usec = ppc_tb_freq / 1000000; - tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000); calc_cputime_factors(); setup_cputime_one_jiffy(); /* - * Calculate the length of each tick in ns. It will not be - * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ. - * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq, - * rounded up. - */ - x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1; - do_div(x, ppc_tb_freq); - tick_nsec = x; - last_tick_len = x << TICKLEN_SCALE; - - /* - * Compute ticklen_to_xs, which is a factor which gets multiplied - * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value. - * It is computed as: - * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9) - * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT - * which turns out to be N = 51 - SHIFT_HZ. - * This gives the result as a 0.64 fixed-point fraction. - * That value is reduced by an offset amounting to 1 xsec per - * 2^31 timebase ticks to avoid problems with time going backwards - * by 1 xsec when we do timer_recalc_offset due to losing the - * fractional xsec. That offset is equal to ppc_tb_freq/2^51 - * since there are 2^20 xsec in a second. - */ - div128_by_32((1ULL << 51) - ppc_tb_freq, 0, - tb_ticks_per_jiffy << SHIFT_HZ, &res); - div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res); - ticklen_to_xs = res.result_low; - - /* Compute tb_to_xs from tick_nsec */ - tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs); - - /* * Compute scale factor for sched_clock. * The calibrate_decr() function has set tb_ticks_per_sec, * which is the timebase frequency. @@ -1087,21 +988,14 @@ void __init time_init(void) /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */ boot_tb = get_tb_or_rtc(); - write_seqlock_irqsave(&xtime_lock, flags); - /* If platform provided a timezone (pmac), we correct the time */ if (timezone_offset) { sys_tz.tz_minuteswest = -timezone_offset / 60; sys_tz.tz_dsttime = 0; } - vdso_data->tb_orig_stamp = tb_last_jiffy; vdso_data->tb_update_count = 0; vdso_data->tb_ticks_per_sec = tb_ticks_per_sec; - vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC; - vdso_data->tb_to_xs = tb_to_xs; - - write_sequnlock_irqrestore(&xtime_lock, flags); /* Start the decrementer on CPUs that have manual control * such as BookE @@ -1195,39 +1089,6 @@ void to_tm(int tim, struct rtc_time * tm) GregorianDay(tm); } -/* Auxiliary function to compute scaling factors */ -/* Actually the choice of a timebase running at 1/4 the of the bus - * frequency giving resolution of a few tens of nanoseconds is quite nice. - * It makes this computation very precise (27-28 bits typically) which - * is optimistic considering the stability of most processor clock - * oscillators and the precision with which the timebase frequency - * is measured but does not harm. - */ -unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale) -{ - unsigned mlt=0, tmp, err; - /* No concern for performance, it's done once: use a stupid - * but safe and compact method to find the multiplier. - */ - - for (tmp = 1U<<31; tmp != 0; tmp >>= 1) { - if (mulhwu(inscale, mlt|tmp) < outscale) - mlt |= tmp; - } - - /* We might still be off by 1 for the best approximation. - * A side effect of this is that if outscale is too large - * the returned value will be zero. - * Many corner cases have been checked and seem to work, - * some might have been forgotten in the test however. - */ - - err = inscale * (mlt+1); - if (err <= inscale/2) - mlt++; - return mlt; -} - /* * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit * result. |