/* * Common time routines among all ppc machines. * * Written by Cort Dougan (cort@cs.nmt.edu) to merge * Paul Mackerras' version and mine for PReP and Pmac. * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net). * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com) * * First round of bugfixes by Gabriel Paubert (paubert@iram.es) * to make clock more stable (2.4.0-test5). The only thing * that this code assumes is that the timebases have been synchronized * by firmware on SMP and are never stopped (never do sleep * on SMP then, nap and doze are OK). * * Speeded up do_gettimeofday by getting rid of references to * xtime (which required locks for consistency). (mikejc@us.ibm.com) * * TODO (not necessarily in this file): * - improve precision and reproducibility of timebase frequency * measurement at boot time. (for iSeries, we calibrate the timebase * against the Titan chip's clock.) * - for astronomical applications: add a new function to get * non ambiguous timestamps even around leap seconds. This needs * a new timestamp format and a good name. * * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 * "A Kernel Model for Precision Timekeeping" by Dave Mills * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_PPC64 #include #endif #ifdef CONFIG_PPC_ISERIES #include #include #endif #include /* keep track of when we need to update the rtc */ time_t last_rtc_update; #ifdef CONFIG_PPC_ISERIES unsigned long iSeries_recal_titan = 0; unsigned long iSeries_recal_tb = 0; static unsigned long first_settimeofday = 1; #endif /* The decrementer counts down by 128 every 128ns on a 601. */ #define DECREMENTER_COUNT_601 (1000000000 / HZ) #define XSEC_PER_SEC (1024*1024) #ifdef CONFIG_PPC64 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC) #else /* compute ((xsec << 12) * max) >> 32 */ #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max) #endif unsigned long tb_ticks_per_jiffy; 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 TICK_LENGTH_SHIFT u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */ 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); u64 tb_to_ns_scale; unsigned tb_to_ns_shift; struct gettimeofday_struct do_gtod; extern unsigned long wall_jiffies; extern struct timezone sys_tz; static long timezone_offset; unsigned long ppc_proc_freq; unsigned long ppc_tb_freq; static u64 tb_last_jiffy __cacheline_aligned_in_smp; static DEFINE_PER_CPU(u64, last_jiffy); #ifdef CONFIG_VIRT_CPU_ACCOUNTING /* * Factors for converting from cputime_t (timebase ticks) to * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds). * These are all stored as 0.64 fixed-point binary fractions. */ u64 __cputime_jiffies_factor; EXPORT_SYMBOL(__cputime_jiffies_factor); u64 __cputime_msec_factor; EXPORT_SYMBOL(__cputime_msec_factor); u64 __cputime_sec_factor; EXPORT_SYMBOL(__cputime_sec_factor); u64 __cputime_clockt_factor; EXPORT_SYMBOL(__cputime_clockt_factor); static void calc_cputime_factors(void) { struct div_result res; div128_by_32(HZ, 0, tb_ticks_per_sec, &res); __cputime_jiffies_factor = res.result_low; div128_by_32(1000, 0, tb_ticks_per_sec, &res); __cputime_msec_factor = res.result_low; div128_by_32(1, 0, tb_ticks_per_sec, &res); __cputime_sec_factor = res.result_low; div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res); __cputime_clockt_factor = res.result_low; } /* * Read the PURR on systems that have it, otherwise the timebase. */ static u64 read_purr(void) { if (cpu_has_feature(CPU_FTR_PURR)) return mfspr(SPRN_PURR); return mftb(); } /* * Account time for a transition between system, hard irq * or soft irq state. */ void account_system_vtime(struct task_struct *tsk) { u64 now, delta; unsigned long flags; local_irq_save(flags); now = read_purr(); delta = now - get_paca()->startpurr; get_paca()->startpurr = now; if (!in_interrupt()) { delta += get_paca()->system_time; get_paca()->system_time = 0; } account_system_time(tsk, 0, delta); local_irq_restore(flags); } /* * Transfer the user and system times accumulated in the paca * by the exception entry and exit code to the generic process * user and system time records. * Must be called with interrupts disabled. */ void account_process_vtime(struct task_struct *tsk) { cputime_t utime; utime = get_paca()->user_time; get_paca()->user_time = 0; account_user_time(tsk, utime); } static void account_process_time(struct pt_regs *regs) { int cpu = smp_processor_id(); account_process_vtime(current); run_local_timers(); if (rcu_pending(cpu)) rcu_check_callbacks(cpu, user_mode(regs)); scheduler_tick(); run_posix_cpu_timers(current); } #ifdef CONFIG_PPC_SPLPAR /* * Stuff for accounting stolen time. */ struct cpu_purr_data { int initialized; /* thread is running */ u64 tb0; /* timebase at origin time */ u64 purr0; /* PURR at origin time */ u64 tb; /* last TB value read */ u64 purr; /* last PURR value read */ u64 stolen; /* stolen time so far */ spinlock_t lock; }; static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data); static void snapshot_tb_and_purr(void *data) { struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data); p->tb0 = mftb(); p->purr0 = mfspr(SPRN_PURR); p->tb = p->tb0; p->purr = 0; wmb(); p->initialized = 1; } /* * Called during boot when all cpus have come up. */ void snapshot_timebases(void) { int cpu; if (!cpu_has_feature(CPU_FTR_PURR)) return; for_each_possible_cpu(cpu) spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock); on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1); } void calculate_steal_time(void) { u64 tb, purr, t0; s64 stolen; struct cpu_purr_data *p0, *pme, *phim; int cpu; if (!cpu_has_feature(CPU_FTR_PURR)) return; cpu = smp_processor_id(); pme = &per_cpu(cpu_purr_data, cpu); if (!pme->initialized) return; /* this can happen in early boot */ p0 = &per_cpu(cpu_purr_data, cpu & ~1); phim = &per_cpu(cpu_purr_data, cpu ^ 1); spin_lock(&p0->lock); tb = mftb(); purr = mfspr(SPRN_PURR) - pme->purr0; if (!phim->initialized || !cpu_online(cpu ^ 1)) { stolen = (tb - pme->tb) - (purr - pme->purr); } else { t0 = pme->tb0; if (phim->tb0 < t0) t0 = phim->tb0; stolen = phim->tb - t0 - phim->purr - purr - p0->stolen; } if (stolen > 0) { account_steal_time(current, stolen); p0->stolen += stolen; } pme->tb = tb; pme->purr = purr; spin_unlock(&p0->lock); } /* * 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) { int cpu; u64 purr; struct cpu_purr_data *p0, *pme, *phim; unsigned long flags; if (!cpu_has_feature(CPU_FTR_PURR)) return; cpu = smp_processor_id(); pme = &per_cpu(cpu_purr_data, cpu); p0 = &per_cpu(cpu_purr_data, cpu & ~1); phim = &per_cpu(cpu_purr_data, cpu ^ 1); spin_lock_irqsave(&p0->lock, flags); pme->tb = pme->tb0 = mftb(); purr = mfspr(SPRN_PURR); if (!phim->initialized) { pme->purr = 0; pme->purr0 = purr; } else { /* set p->purr and p->purr0 for no change in p0->stolen */ pme->purr = phim->tb - phim->tb0 - phim->purr - p0->stolen; pme->purr0 = purr - pme->purr; } pme->initialized = 1; spin_unlock_irqrestore(&p0->lock, flags); } #endif /* CONFIG_PPC_SPLPAR */ #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */ #define calc_cputime_factors() #define account_process_time(regs) update_process_times(user_mode(regs)) #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(); snapshot_purr(); } void __delay(unsigned long loops) { unsigned long start; int diff; if (__USE_RTC()) { start = get_rtcl(); do { /* the RTCL register wraps at 1000000000 */ diff = get_rtcl() - start; if (diff < 0) diff += 1000000000; } while (diff < loops); } else { start = get_tbl(); while (get_tbl() - start < loops) HMT_low(); HMT_medium(); } } EXPORT_SYMBOL(__delay); void udelay(unsigned long usecs) { __delay(tb_ticks_per_usec * usecs); } EXPORT_SYMBOL(udelay); static __inline__ void timer_check_rtc(void) { /* * update the rtc when needed, this should be performed on the * right fraction of a second. Half or full second ? * Full second works on mk48t59 clocks, others need testing. * Note that this update is basically only used through * the adjtimex system calls. Setting the HW clock in * any other way is a /dev/rtc and userland business. * This is still wrong by -0.5/+1.5 jiffies because of the * timer interrupt resolution and possible delay, but here we * hit a quantization limit which can only be solved by higher * resolution timers and decoupling time management from timer * interrupts. This is also wrong on the clocks * which require being written at the half second boundary. * We should have an rtc call that only sets the minutes and * seconds like on Intel to avoid problems with non UTC clocks. */ if (ppc_md.set_rtc_time && ntp_synced() && xtime.tv_sec - last_rtc_update >= 659 && abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ) { struct rtc_time tm; to_tm(xtime.tv_sec + 1 + timezone_offset, &tm); tm.tm_year -= 1900; tm.tm_mon -= 1; if (ppc_md.set_rtc_time(&tm) == 0) last_rtc_update = xtime.tv_sec + 1; else /* Try again one minute later */ last_rtc_update += 60; } } /* * This version of gettimeofday has microsecond resolution. */ static inline void __do_gettimeofday(struct timeval *tv) { unsigned long sec, usec; u64 tb_ticks, xsec; struct gettimeofday_vars *temp_varp; u64 temp_tb_to_xs, temp_stamp_xsec; /* * These calculations are faster (gets rid of divides) * if done in units of 1/2^20 rather than microseconds. * The conversion to microseconds at the end is done * without a divide (and in fact, without a multiply) */ temp_varp = do_gtod.varp; /* Sampling the time base must be done after loading * do_gtod.varp in order to avoid racing with update_gtod. */ data_barrier(temp_varp); tb_ticks = get_tb() - temp_varp->tb_orig_stamp; temp_tb_to_xs = temp_varp->tb_to_xs; temp_stamp_xsec = temp_varp->stamp_xsec; xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs); sec = xsec / XSEC_PER_SEC; usec = (unsigned long)xsec & (XSEC_PER_SEC - 1); usec = SCALE_XSEC(usec, 1000000); tv->tv_sec = sec; tv->tv_usec = usec; } void do_gettimeofday(struct timeval *tv) { if (__USE_RTC()) { /* do this the old way */ unsigned long flags, seq; unsigned int sec, nsec, usec; do { seq = read_seqbegin_irqsave(&xtime_lock, flags); sec = xtime.tv_sec; nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy); } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); usec = nsec / 1000; while (usec >= 1000000) { usec -= 1000000; ++sec; } tv->tv_sec = sec; tv->tv_usec = usec; return; } __do_gettimeofday(tv); } EXPORT_SYMBOL(do_gettimeofday); /* * There are two copies of tb_to_xs and stamp_xsec so that no * lock is needed to access and use these values in * do_gettimeofday. We alternate the copies and as long as a * reasonable time elapses between changes, there will never * be inconsistent values. ntpd has a minimum of one minute * between updates. */ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec, u64 new_tb_to_xs) { unsigned temp_idx; struct gettimeofday_vars *temp_varp; temp_idx = (do_gtod.var_idx == 0); temp_varp = &do_gtod.vars[temp_idx]; temp_varp->tb_to_xs = new_tb_to_xs; temp_varp->tb_orig_stamp = new_tb_stamp; temp_varp->stamp_xsec = new_stamp_xsec; smp_mb(); do_gtod.varp = temp_varp; do_gtod.var_idx = temp_idx; /* * 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; smp_wmb(); ++(vdso_data->tb_update_count); } /* * When the timebase - tb_orig_stamp gets too big, we do a manipulation * between tb_orig_stamp and stamp_xsec. The goal here is to keep the * difference tb - tb_orig_stamp small enough to always fit inside a * 32 bits number. This is a requirement of our fast 32 bits userland * implementation in the vdso. If we "miss" a call to this function * (interrupt latency, CPU locked in a spinlock, ...) and we end up * with a too big difference, then the vdso will fallback to calling * the syscall */ static __inline__ void timer_recalc_offset(u64 cur_tb) { unsigned long offset; u64 new_stamp_xsec; u64 tlen, t2x; u64 tb, xsec_old, xsec_new; struct gettimeofday_vars *varp; if (__USE_RTC()) return; tlen = current_tick_length(); offset = cur_tb - do_gtod.varp->tb_orig_stamp; if (tlen == last_tick_len && offset < 0x80000000u) return; if (tlen != last_tick_len) { t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs); last_tick_len = tlen; } else t2x = do_gtod.varp->tb_to_xs; new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC; do_div(new_stamp_xsec, 1000000000); new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC; ++vdso_data->tb_update_count; smp_mb(); /* * Make sure time doesn't go backwards for userspace gettimeofday. */ tb = get_tb(); varp = do_gtod.varp; xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs) + varp->stamp_xsec; xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec; if (xsec_new < xsec_old) new_stamp_xsec += xsec_old - xsec_new; update_gtod(cur_tb, new_stamp_xsec, t2x); } #ifdef CONFIG_SMP unsigned long profile_pc(struct pt_regs *regs) { unsigned long pc = instruction_pointer(regs); if (in_lock_functions(pc)) return regs->link; return pc; } EXPORT_SYMBOL(profile_pc); #endif #ifdef CONFIG_PPC_ISERIES /* * This function recalibrates the timebase based on the 49-bit time-of-day * value in the Titan chip. The Titan is much more accurate than the value * returned by the service processor for the timebase frequency. */ static void iSeries_tb_recal(void) { struct div_result divres; unsigned long titan, tb; tb = get_tb(); titan = HvCallXm_loadTod(); if ( iSeries_recal_titan ) { unsigned long tb_ticks = tb - iSeries_recal_tb; unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12; unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec; unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ; long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy; char sign = '+'; /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */ new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ; if ( tick_diff < 0 ) { tick_diff = -tick_diff; sign = '-'; } if ( tick_diff ) { if ( tick_diff < tb_ticks_per_jiffy/25 ) { printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n", new_tb_ticks_per_jiffy, sign, tick_diff ); 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 ); do_gtod.tb_ticks_per_sec = tb_ticks_per_sec; tb_to_xs = divres.result_low; do_gtod.varp->tb_to_xs = tb_to_xs; vdso_data->tb_ticks_per_sec = tb_ticks_per_sec; vdso_data->tb_to_xs = tb_to_xs; } else { printk( "Titan recalibrate: FAILED (difference > 4 percent)\n" " new tb_ticks_per_jiffy = %lu\n" " old tb_ticks_per_jiffy = %lu\n", new_tb_ticks_per_jiffy, tb_ticks_per_jiffy ); } } } iSeries_recal_titan = titan; iSeries_recal_tb = tb; } #endif /* * For iSeries shared processors, we have to let the hypervisor * set the hardware decrementer. We set a virtual decrementer * in the lppaca and call the hypervisor if the virtual * decrementer is less than the current value in the hardware * decrementer. (almost always the new decrementer value will * be greater than the current hardware decementer so the hypervisor * call will not be needed) */ /* * timer_interrupt - gets called when the decrementer overflows, * with interrupts disabled. */ void timer_interrupt(struct pt_regs * regs) { int next_dec; int cpu = smp_processor_id(); unsigned long ticks; u64 tb_next_jiffy; #ifdef CONFIG_PPC32 if (atomic_read(&ppc_n_lost_interrupts) != 0) do_IRQ(regs); #endif irq_enter(); profile_tick(CPU_PROFILING, regs); calculate_steal_time(); #ifdef CONFIG_PPC_ISERIES get_lppaca()->int_dword.fields.decr_int = 0; #endif while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu))) >= tb_ticks_per_jiffy) { /* Update last_jiffy */ per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy; /* Handle RTCL overflow on 601 */ if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000) per_cpu(last_jiffy, cpu) -= 1000000000; /* * We cannot disable the decrementer, so in the period * between this cpu's being marked offline in cpu_online_map * and calling stop-self, it is taking timer interrupts. * Avoid calling into the scheduler rebalancing code if this * is the case. */ if (!cpu_is_offline(cpu)) account_process_time(regs); /* * No need to check whether cpu is offline here; boot_cpuid * should have been fixed up by now. */ if (cpu != boot_cpuid) continue; write_seqlock(&xtime_lock); tb_next_jiffy = tb_last_jiffy + tb_ticks_per_jiffy; if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) { tb_last_jiffy = tb_next_jiffy; do_timer(regs); timer_recalc_offset(tb_last_jiffy); timer_check_rtc(); } write_sequnlock(&xtime_lock); } next_dec = tb_ticks_per_jiffy - ticks; set_dec(next_dec); #ifdef CONFIG_PPC_ISERIES if (hvlpevent_is_pending()) process_hvlpevents(regs); #endif #ifdef CONFIG_PPC64 /* collect purr register values often, for accurate calculations */ if (firmware_has_feature(FW_FEATURE_SPLPAR)) { struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array); cu->current_tb = mfspr(SPRN_PURR); } #endif irq_exit(); } 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_SMP void __init smp_space_timers(unsigned int max_cpus) { int i; unsigned long half = tb_ticks_per_jiffy / 2; unsigned long offset = tb_ticks_per_jiffy / max_cpus; 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; /* * The stolen time calculation for POWER5 shared-processor LPAR * systems works better if the two threads' timebase interrupts * are staggered by half a jiffy with respect to each other. */ for_each_possible_cpu(i) { if (i == boot_cpuid) continue; if (i == (boot_cpuid ^ 1)) per_cpu(last_jiffy, i) = per_cpu(last_jiffy, boot_cpuid) - half; else if (i & 1) per_cpu(last_jiffy, i) = per_cpu(last_jiffy, i ^ 1) + half; else { previous_tb += offset; per_cpu(last_jiffy, i) = previous_tb; } } } #endif /* * Scheduler clock - returns current time in nanosec units. * * Note: mulhdu(a, b) (multiply high double unsigned) returns * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b * are 64-bit unsigned numbers. */ unsigned long long sched_clock(void) { if (__USE_RTC()) return get_rtc(); return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift; } int do_settimeofday(struct timespec *tv) { time_t wtm_sec, new_sec = tv->tv_sec; long wtm_nsec, new_nsec = tv->tv_nsec; unsigned long flags; u64 new_xsec; unsigned long tb_delta; if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) return -EINVAL; write_seqlock_irqsave(&xtime_lock, flags); /* * Updating the RTC is not the job of this code. If the time is * stepped under NTP, the RTC will be updated after STA_UNSYNC * is cleared. Tools like clock/hwclock either copy the RTC * to the system time, in which case there is no point in writing * to the RTC again, or write to the RTC but then they don't call * settimeofday to perform this operation. */ #ifdef CONFIG_PPC_ISERIES if (first_settimeofday) { iSeries_tb_recal(); first_settimeofday = 0; } #endif /* Make userspace gettimeofday spin until we're done. */ ++vdso_data->tb_update_count; smp_mb(); /* * Subtract off the number of nanoseconds since the * beginning of the last tick. * Note that since we don't increment jiffies_64 anywhere other * than in do_timer (since we don't have a lost tick problem), * wall_jiffies will always be the same as jiffies, * and therefore the (jiffies - wall_jiffies) computation * has been removed. */ tb_delta = tb_ticks_since(tb_last_jiffy); tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */ new_nsec -= SCALE_XSEC(tb_delta, 1000000000); wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec); wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec); set_normalized_timespec(&xtime, new_sec, new_nsec); set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); /* In case of a large backwards jump in time with NTP, we want the * clock to be updated as soon as the PLL is again in lock. */ last_rtc_update = new_sec - 658; ntp_clear(); new_xsec = xtime.tv_nsec; if (new_xsec != 0) { new_xsec *= XSEC_PER_SEC; do_div(new_xsec, NSEC_PER_SEC); } new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC; update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs); vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; vdso_data->tz_dsttime = sys_tz.tz_dsttime; write_sequnlock_irqrestore(&xtime_lock, flags); clock_was_set(); return 0; } EXPORT_SYMBOL(do_settimeofday); static int __init get_freq(char *name, int cells, unsigned long *val) { struct device_node *cpu; const unsigned int *fp; int found = 0; /* The cpu node should have timebase and clock frequency properties */ cpu = of_find_node_by_type(NULL, "cpu"); if (cpu) { fp = get_property(cpu, name, NULL); if (fp) { found = 1; *val = of_read_ulong(fp, cells); } of_node_put(cpu); } return found; } void __init generic_calibrate_decr(void) { ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */ if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) && !get_freq("timebase-frequency", 1, &ppc_tb_freq)) { printk(KERN_ERR "WARNING: Estimating decrementer frequency " "(not found)\n"); } ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */ if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) && !get_freq("clock-frequency", 1, &ppc_proc_freq)) { printk(KERN_ERR "WARNING: Estimating processor frequency " "(not found)\n"); } #ifdef CONFIG_BOOKE /* Set the time base to zero */ mtspr(SPRN_TBWL, 0); mtspr(SPRN_TBWU, 0); /* Clear any pending timer interrupts */ mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS); /* Enable decrementer interrupt */ mtspr(SPRN_TCR, TCR_DIE); #endif } unsigned long get_boot_time(void) { struct rtc_time tm; if (ppc_md.get_boot_time) return ppc_md.get_boot_time(); if (!ppc_md.get_rtc_time) return 0; ppc_md.get_rtc_time(&tm); return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); } /* This function is only called on the boot processor */ void __init time_init(void) { unsigned long flags; unsigned long tm = 0; struct div_result res; u64 scale, x; unsigned shift; if (ppc_md.time_init != NULL) timezone_offset = ppc_md.time_init(); 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(); printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n", 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(); /* * 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. * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret * the 128-bit result as a 64.64 fixed-point number. * We then shift that number right until it is less than 1.0, * giving us the scale factor and shift count to use in * sched_clock(). */ div128_by_32(1000000000, 0, tb_ticks_per_sec, &res); scale = res.result_low; for (shift = 0; res.result_high != 0; ++shift) { scale = (scale >> 1) | (res.result_high << 63); res.result_high >>= 1; } tb_to_ns_scale = scale; tb_to_ns_shift = shift; tm = get_boot_time(); 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; tm -= timezone_offset; } xtime.tv_sec = tm; xtime.tv_nsec = 0; do_gtod.varp = &do_gtod.vars[0]; do_gtod.var_idx = 0; do_gtod.varp->tb_orig_stamp = tb_last_jiffy; __get_cpu_var(last_jiffy) = tb_last_jiffy; do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC; do_gtod.tb_ticks_per_sec = tb_ticks_per_sec; do_gtod.varp->tb_to_xs = tb_to_xs; do_gtod.tb_to_us = tb_to_us; 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; time_freq = 0; last_rtc_update = xtime.tv_sec; set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); write_sequnlock_irqrestore(&xtime_lock, flags); /* Not exact, but the timer interrupt takes care of this */ set_dec(tb_ticks_per_jiffy); } #define FEBRUARY 2 #define STARTOFTIME 1970 #define SECDAY 86400L #define SECYR (SECDAY * 365) #define leapyear(year) ((year) % 4 == 0 && \ ((year) % 100 != 0 || (year) % 400 == 0)) #define days_in_year(a) (leapyear(a) ? 366 : 365) #define days_in_month(a) (month_days[(a) - 1]) static int month_days[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; /* * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) */ void GregorianDay(struct rtc_time * tm) { int leapsToDate; int lastYear; int day; int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 }; lastYear = tm->tm_year - 1; /* * Number of leap corrections to apply up to end of last year */ leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400; /* * This year is a leap year if it is divisible by 4 except when it is * divisible by 100 unless it is divisible by 400 * * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was */ day = tm->tm_mon > 2 && leapyear(tm->tm_year); day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday; tm->tm_wday = day % 7; } void to_tm(int tim, struct rtc_time * tm) { register int i; register long hms, day; day = tim / SECDAY; hms = tim % SECDAY; /* Hours, minutes, seconds are easy */ tm->tm_hour = hms / 3600; tm->tm_min = (hms % 3600) / 60; tm->tm_sec = (hms % 3600) % 60; /* Number of years in days */ for (i = STARTOFTIME; day >= days_in_year(i); i++) day -= days_in_year(i); tm->tm_year = i; /* Number of months in days left */ if (leapyear(tm->tm_year)) days_in_month(FEBRUARY) = 29; for (i = 1; day >= days_in_month(i); i++) day -= days_in_month(i); days_in_month(FEBRUARY) = 28; tm->tm_mon = i; /* Days are what is left over (+1) from all that. */ tm->tm_mday = day + 1; /* * Determine the day of week */ 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. */ void div128_by_32(u64 dividend_high, u64 dividend_low, unsigned divisor, struct div_result *dr) { unsigned long a, b, c, d; unsigned long w, x, y, z; u64 ra, rb, rc; a = dividend_high >> 32; b = dividend_high & 0xffffffff; c = dividend_low >> 32; d = dividend_low & 0xffffffff; w = a / divisor; ra = ((u64)(a - (w * divisor)) << 32) + b; rb = ((u64) do_div(ra, divisor) << 32) + c; x = ra; rc = ((u64) do_div(rb, divisor) << 32) + d; y = rb; do_div(rc, divisor); z = rc; dr->result_high = ((u64)w << 32) + x; dr->result_low = ((u64)y << 32) + z; }