// SPDX-License-Identifier: GPL-2.0-or-later /* * 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 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 */ #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 #include #include #include #include #include #include #include #include #include #include /* powerpc clocksource/clockevent code */ #include #include static u64 rtc_read(struct clocksource *); static struct clocksource clocksource_rtc = { .name = "rtc", .rating = 400, .flags = CLOCK_SOURCE_IS_CONTINUOUS, .mask = CLOCKSOURCE_MASK(64), .read = rtc_read, }; static u64 timebase_read(struct clocksource *); static struct clocksource clocksource_timebase = { .name = "timebase", .rating = 400, .flags = CLOCK_SOURCE_IS_CONTINUOUS, .mask = CLOCKSOURCE_MASK(64), .read = timebase_read, }; #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF u64 decrementer_max = DECREMENTER_DEFAULT_MAX; static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev); static int decrementer_shutdown(struct clock_event_device *evt); struct clock_event_device decrementer_clockevent = { .name = "decrementer", .rating = 200, .irq = 0, .set_next_event = decrementer_set_next_event, .set_state_oneshot_stopped = decrementer_shutdown, .set_state_shutdown = decrementer_shutdown, .tick_resume = decrementer_shutdown, .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP, }; EXPORT_SYMBOL(decrementer_clockevent); DEFINE_PER_CPU(u64, decrementers_next_tb); static DEFINE_PER_CPU(struct clock_event_device, decrementers); #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 */ DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL_GPL(rtc_lock); static u64 tb_to_ns_scale __read_mostly; static unsigned tb_to_ns_shift __read_mostly; static u64 boot_tb __read_mostly; extern struct timezone sys_tz; static long timezone_offset; unsigned long ppc_proc_freq; EXPORT_SYMBOL_GPL(ppc_proc_freq); unsigned long ppc_tb_freq; EXPORT_SYMBOL_GPL(ppc_tb_freq); bool tb_invalid; #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE /* * Factor for converting from cputime_t (timebase ticks) to * microseconds. This is stored as 0.64 fixed-point binary fraction. */ u64 __cputime_usec_factor; EXPORT_SYMBOL(__cputime_usec_factor); #ifdef CONFIG_PPC_SPLPAR void (*dtl_consumer)(struct dtl_entry *, u64); #endif static void calc_cputime_factors(void) { struct div_result res; div128_by_32(1000000, 0, tb_ticks_per_sec, &res); __cputime_usec_factor = res.result_low; } /* * Read the SPURR on systems that have it, otherwise the PURR, * or if that doesn't exist return the timebase value passed in. */ static inline unsigned long read_spurr(unsigned long tb) { if (cpu_has_feature(CPU_FTR_SPURR)) return mfspr(SPRN_SPURR); if (cpu_has_feature(CPU_FTR_PURR)) return mfspr(SPRN_PURR); return tb; } #ifdef CONFIG_PPC_SPLPAR /* * Scan the dispatch trace log and count up the stolen time. * Should be called with interrupts disabled. */ static u64 scan_dispatch_log(u64 stop_tb) { 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 (!dtl) return 0; if (i == be64_to_cpu(vpa->dtl_idx)) return 0; while (i < be64_to_cpu(vpa->dtl_idx)) { dtb = be64_to_cpu(dtl->timebase); tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) + be32_to_cpu(dtl->ready_to_enqueue_time); barrier(); if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) { /* buffer has overflowed */ i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG; dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG); continue; } if (dtb > stop_tb) break; if (dtl_consumer) dtl_consumer(dtl, i); 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 notrace accumulate_stolen_time(void) { u64 sst, ust; unsigned long save_irq_soft_mask = irq_soft_mask_return(); struct cpu_accounting_data *acct = &local_paca->accounting; /* We are called early in the exception entry, before * soft/hard_enabled are sync'ed to the expected state * for the exception. We are hard disabled but the PACA * needs to reflect that so various debug stuff doesn't * complain */ irq_soft_mask_set(IRQS_DISABLED); sst = scan_dispatch_log(acct->starttime_user); ust = scan_dispatch_log(acct->starttime); acct->stime -= sst; acct->utime -= ust; acct->steal_time += ust + sst; irq_soft_mask_set(save_irq_soft_mask); } static inline u64 calculate_stolen_time(u64 stop_tb) { if (!firmware_has_feature(FW_FEATURE_SPLPAR)) return 0; if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) return scan_dispatch_log(stop_tb); return 0; } #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. */ static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct, unsigned long now, unsigned long stime) { unsigned long stime_scaled = 0; #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long nowscaled, deltascaled; unsigned long utime, utime_scaled; nowscaled = read_spurr(now); deltascaled = nowscaled - acct->startspurr; acct->startspurr = nowscaled; utime = acct->utime - acct->utime_sspurr; acct->utime_sspurr = acct->utime; /* * 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. */ stime_scaled = stime; utime_scaled = utime; if (deltascaled != stime + utime) { if (utime) { stime_scaled = deltascaled * stime / (stime + utime); utime_scaled = deltascaled - stime_scaled; } else { stime_scaled = deltascaled; } } acct->utime_scaled += utime_scaled; #endif return stime_scaled; } static unsigned long vtime_delta(struct task_struct *tsk, unsigned long *stime_scaled, unsigned long *steal_time) { unsigned long now, stime; struct cpu_accounting_data *acct = get_accounting(tsk); WARN_ON_ONCE(!irqs_disabled()); now = mftb(); stime = now - acct->starttime; acct->starttime = now; *stime_scaled = vtime_delta_scaled(acct, now, stime); *steal_time = calculate_stolen_time(now); return stime; } void vtime_account_system(struct task_struct *tsk) { unsigned long stime, stime_scaled, steal_time; struct cpu_accounting_data *acct = get_accounting(tsk); stime = vtime_delta(tsk, &stime_scaled, &steal_time); stime -= min(stime, steal_time); acct->steal_time += steal_time; if ((tsk->flags & PF_VCPU) && !irq_count()) { acct->gtime += stime; #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME acct->utime_scaled += stime_scaled; #endif } else { if (hardirq_count()) acct->hardirq_time += stime; else if (in_serving_softirq()) acct->softirq_time += stime; else acct->stime += stime; #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME acct->stime_scaled += stime_scaled; #endif } } EXPORT_SYMBOL_GPL(vtime_account_system); void vtime_account_idle(struct task_struct *tsk) { unsigned long stime, stime_scaled, steal_time; struct cpu_accounting_data *acct = get_accounting(tsk); stime = vtime_delta(tsk, &stime_scaled, &steal_time); acct->idle_time += stime + steal_time; } static void vtime_flush_scaled(struct task_struct *tsk, struct cpu_accounting_data *acct) { #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME if (acct->utime_scaled) tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled); if (acct->stime_scaled) tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled); acct->utime_scaled = 0; acct->utime_sspurr = 0; acct->stime_scaled = 0; #endif } /* * Account the whole cputime accumulated in the paca * Must be called with interrupts disabled. * Assumes that vtime_account_system/idle() has been called * recently (i.e. since the last entry from usermode) so that * get_paca()->user_time_scaled is up to date. */ void vtime_flush(struct task_struct *tsk) { struct cpu_accounting_data *acct = get_accounting(tsk); if (acct->utime) account_user_time(tsk, cputime_to_nsecs(acct->utime)); if (acct->gtime) account_guest_time(tsk, cputime_to_nsecs(acct->gtime)); if (IS_ENABLED(CONFIG_PPC_SPLPAR) && acct->steal_time) { account_steal_time(cputime_to_nsecs(acct->steal_time)); acct->steal_time = 0; } if (acct->idle_time) account_idle_time(cputime_to_nsecs(acct->idle_time)); if (acct->stime) account_system_index_time(tsk, cputime_to_nsecs(acct->stime), CPUTIME_SYSTEM); if (acct->hardirq_time) account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time), CPUTIME_IRQ); if (acct->softirq_time) account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time), CPUTIME_SOFTIRQ); vtime_flush_scaled(tsk, acct); acct->utime = 0; acct->gtime = 0; acct->idle_time = 0; acct->stime = 0; acct->hardirq_time = 0; acct->softirq_time = 0; } #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ #define calc_cputime_factors() #endif void __delay(unsigned long loops) { unsigned long start; int diff; spin_begin(); if (__USE_RTC()) { start = get_rtcl(); do { /* the RTCL register wraps at 1000000000 */ diff = get_rtcl() - start; if (diff < 0) diff += 1000000000; spin_cpu_relax(); } while (diff < loops); } else if (tb_invalid) { /* * TB is in error state and isn't ticking anymore. * HMI handler was unable to recover from TB error. * Return immediately, so that kernel won't get stuck here. */ spin_cpu_relax(); } else { start = get_tbl(); while (get_tbl() - start < loops) spin_cpu_relax(); } spin_end(); } EXPORT_SYMBOL(__delay); void udelay(unsigned long usecs) { __delay(tb_ticks_per_usec * usecs); } EXPORT_SYMBOL(udelay); #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_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_irq_work_pending(void) { unsigned long x; asm volatile("lbz %0,%1(13)" : "=r" (x) : "i" (offsetof(struct paca_struct, irq_work_pending))); return x; } static inline void set_irq_work_pending_flag(void) { asm volatile("stb %0,%1(13)" : : "r" (1), "i" (offsetof(struct paca_struct, irq_work_pending))); } static inline void clear_irq_work_pending(void) { asm volatile("stb %0,%1(13)" : : "r" (0), "i" (offsetof(struct paca_struct, irq_work_pending))); } void arch_irq_work_raise(void) { preempt_disable(); set_irq_work_pending_flag(); /* * Non-nmi code running with interrupts disabled will replay * irq_happened before it re-enables interrupts, so setthe * decrementer there instead of causing a hardware exception * which would immediately hit the masked interrupt handler * and have the net effect of setting the decrementer in * irq_happened. * * NMI interrupts can not check this when they return, so the * decrementer hardware exception is raised, which will fire * when interrupts are next enabled. * * BookE does not support this yet, it must audit all NMI * interrupt handlers to ensure they call nmi_enter() so this * check would be correct. */ if (IS_ENABLED(CONFIG_BOOKE) || !irqs_disabled() || in_nmi()) { set_dec(1); } else { hard_irq_disable(); local_paca->irq_happened |= PACA_IRQ_DEC; } preempt_enable(); } #else /* 32-bit */ DEFINE_PER_CPU(u8, irq_work_pending); #define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1) #define test_irq_work_pending() __this_cpu_read(irq_work_pending) #define clear_irq_work_pending() __this_cpu_write(irq_work_pending, 0) void arch_irq_work_raise(void) { preempt_disable(); set_irq_work_pending_flag(); set_dec(1); preempt_enable(); } #endif /* 32 vs 64 bit */ #else /* CONFIG_IRQ_WORK */ #define test_irq_work_pending() 0 #define clear_irq_work_pending() #endif /* CONFIG_IRQ_WORK */ /* * timer_interrupt - gets called when the decrementer overflows, * with interrupts disabled. */ void timer_interrupt(struct pt_regs *regs) { struct clock_event_device *evt = this_cpu_ptr(&decrementers); u64 *next_tb = this_cpu_ptr(&decrementers_next_tb); struct pt_regs *old_regs; u64 now; /* Some implementations of hotplug will get timer interrupts while * offline, just ignore these and we also need to set * decrementers_next_tb as MAX to make sure __check_irq_replay * don't replay timer interrupt when return, otherwise we'll trap * here infinitely :( */ if (unlikely(!cpu_online(smp_processor_id()))) { *next_tb = ~(u64)0; set_dec(decrementer_max); return; } /* Ensure a positive value is written to the decrementer, or else * some CPUs will continue to take decrementer exceptions. When the * PPC_WATCHDOG (decrementer based) is configured, keep this at most * 31 bits, which is about 4 seconds on most systems, which gives * the watchdog a chance of catching timer interrupt hard lockups. */ if (IS_ENABLED(CONFIG_PPC_WATCHDOG)) set_dec(0x7fffffff); else set_dec(decrementer_max); /* Conditionally hard-enable interrupts now that the DEC has been * bumped to its maximum value */ may_hard_irq_enable(); #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC) if (atomic_read(&ppc_n_lost_interrupts) != 0) do_IRQ(regs); #endif old_regs = set_irq_regs(regs); irq_enter(); trace_timer_interrupt_entry(regs); if (test_irq_work_pending()) { clear_irq_work_pending(); irq_work_run(); } now = get_tb_or_rtc(); if (now >= *next_tb) { *next_tb = ~(u64)0; if (evt->event_handler) evt->event_handler(evt); __this_cpu_inc(irq_stat.timer_irqs_event); } else { now = *next_tb - now; if (now <= decrementer_max) set_dec(now); /* We may have raced with new irq work */ if (test_irq_work_pending()) set_dec(1); __this_cpu_inc(irq_stat.timer_irqs_others); } trace_timer_interrupt_exit(regs); irq_exit(); set_irq_regs(old_regs); } EXPORT_SYMBOL(timer_interrupt); #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST void timer_broadcast_interrupt(void) { u64 *next_tb = this_cpu_ptr(&decrementers_next_tb); *next_tb = ~(u64)0; tick_receive_broadcast(); __this_cpu_inc(irq_stat.broadcast_irqs_event); } #endif /* * Hypervisor decrementer interrupts shouldn't occur but are sometimes * left pending on exit from a KVM guest. We don't need to do anything * to clear them, as they are edge-triggered. */ void hdec_interrupt(struct pt_regs *regs) { } #ifdef CONFIG_SUSPEND static void generic_suspend_disable_irqs(void) { /* Disable the decrementer, so that it doesn't interfere * with suspending. */ set_dec(decrementer_max); local_irq_disable(); set_dec(decrementer_max); } static void generic_suspend_enable_irqs(void) { local_irq_enable(); } /* Overrides the weak version in kernel/power/main.c */ void arch_suspend_disable_irqs(void) { if (ppc_md.suspend_disable_irqs) ppc_md.suspend_disable_irqs(); generic_suspend_disable_irqs(); } /* Overrides the weak version in kernel/power/main.c */ void arch_suspend_enable_irqs(void) { generic_suspend_enable_irqs(); if (ppc_md.suspend_enable_irqs) ppc_md.suspend_enable_irqs(); } #endif unsigned long long tb_to_ns(unsigned long long ticks) { return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift; } EXPORT_SYMBOL_GPL(tb_to_ns); /* * 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. */ notrace unsigned long long sched_clock(void) { if (__USE_RTC()) return get_rtc(); return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift; } #ifdef CONFIG_PPC_PSERIES /* * Running clock - attempts to give a view of time passing for a virtualised * kernels. * Uses the VTB register if available otherwise a next best guess. */ unsigned long long running_clock(void) { /* * Don't read the VTB as a host since KVM does not switch in host * timebase into the VTB when it takes a guest off the CPU, reading the * VTB would result in reading 'last switched out' guest VTB. * * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it * would be unsafe to rely only on the #ifdef above. */ if (firmware_has_feature(FW_FEATURE_LPAR) && cpu_has_feature(CPU_FTR_ARCH_207S)) return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift; /* * This is a next best approximation without a VTB. * On a host which is running bare metal there should never be any stolen * time and on a host which doesn't do any virtualisation TB *should* equal * VTB so it makes no difference anyway. */ return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL]; } #endif static int __init get_freq(char *name, int cells, unsigned long *val) { struct device_node *cpu; const __be32 *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 = of_get_property(cpu, name, NULL); if (fp) { found = 1; *val = of_read_ulong(fp, cells); } of_node_put(cpu); } return found; } static void start_cpu_decrementer(void) { #if defined(CONFIG_BOOKE) || defined(CONFIG_40x) unsigned int tcr; /* Clear any pending timer interrupts */ mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS); tcr = mfspr(SPRN_TCR); /* * The watchdog may have already been enabled by u-boot. So leave * TRC[WP] (Watchdog Period) alone. */ tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */ tcr |= TCR_DIE; /* Enable decrementer */ mtspr(SPRN_TCR, tcr); #endif } 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"); } } int update_persistent_clock64(struct timespec64 now) { struct rtc_time tm; if (!ppc_md.set_rtc_time) return -ENODEV; rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm); return ppc_md.set_rtc_time(&tm); } static void __read_persistent_clock(struct timespec64 *ts) { struct rtc_time tm; static int first = 1; ts->tv_nsec = 0; /* XXX this is a litle fragile but will work okay in the short term */ if (first) { first = 0; if (ppc_md.time_init) timezone_offset = ppc_md.time_init(); /* get_boot_time() isn't guaranteed to be safe to call late */ if (ppc_md.get_boot_time) { ts->tv_sec = ppc_md.get_boot_time() - timezone_offset; return; } } if (!ppc_md.get_rtc_time) { ts->tv_sec = 0; return; } ppc_md.get_rtc_time(&tm); ts->tv_sec = rtc_tm_to_time64(&tm); } void read_persistent_clock64(struct timespec64 *ts) { __read_persistent_clock(ts); /* Sanitize it in case real time clock is set below EPOCH */ if (ts->tv_sec < 0) { ts->tv_sec = 0; ts->tv_nsec = 0; } } /* clocksource code */ static notrace u64 rtc_read(struct clocksource *cs) { return (u64)get_rtc(); } static notrace u64 timebase_read(struct clocksource *cs) { return (u64)get_tb(); } void update_vsyscall(struct timekeeper *tk) { struct timespec xt; struct clocksource *clock = tk->tkr_mono.clock; u32 mult = tk->tkr_mono.mult; u32 shift = tk->tkr_mono.shift; u64 cycle_last = tk->tkr_mono.cycle_last; u64 new_tb_to_xs, new_stamp_xsec; u64 frac_sec; if (clock != &clocksource_timebase) return; xt.tv_sec = tk->xtime_sec; xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); /* Make userspace gettimeofday spin until we're done. */ ++vdso_data->tb_update_count; smp_mb(); /* * This computes ((2^20 / 1e9) * mult) >> shift as a * 0.64 fixed-point fraction. * The computation in the else clause below won't overflow * (as long as the timebase frequency is >= 1.049 MHz) * but loses precision because we lose the low bits of the constant * in the shift. Note that 19342813113834067 ~= 2^(20+64) / 1e9. * For a shift of 24 the error is about 0.5e-9, or about 0.5ns * over a second. (Shift values are usually 22, 23 or 24.) * For high frequency clocks such as the 512MHz timebase clock * on POWER[6789], the mult value is small (e.g. 32768000) * and so we can shift the constant by 16 initially * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the * remaining shifts after the multiplication, which gives a * more accurate result (e.g. with mult = 32768000, shift = 24, * the error is only about 1.2e-12, or 0.7ns over 10 minutes). */ if (mult <= 62500000 && clock->shift >= 16) new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16); else new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift); /* * Compute the fractional second in units of 2^-32 seconds. * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift * in nanoseconds, so multiplying that by 2^32 / 1e9 gives * it in units of 2^-32 seconds. * We assume shift <= 32 because clocks_calc_mult_shift() * generates shift values in the range 0 - 32. */ frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift); do_div(frac_sec, NSEC_PER_SEC); /* * Work out new stamp_xsec value for any legacy users of systemcfg. * stamp_xsec is in units of 2^-20 seconds. */ new_stamp_xsec = frac_sec >> 12; new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC; /* * 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. */ vdso_data->tb_orig_stamp = cycle_last; vdso_data->stamp_xsec = new_stamp_xsec; vdso_data->tb_to_xs = new_tb_to_xs; vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec; vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec; vdso_data->stamp_xtime = xt; vdso_data->stamp_sec_fraction = frac_sec; vdso_data->hrtimer_res = hrtimer_resolution; smp_wmb(); ++(vdso_data->tb_update_count); } void update_vsyscall_tz(void) { vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; vdso_data->tz_dsttime = sys_tz.tz_dsttime; } static void __init clocksource_init(void) { struct clocksource *clock; if (__USE_RTC()) clock = &clocksource_rtc; else clock = &clocksource_timebase; if (clocksource_register_hz(clock, tb_ticks_per_sec)) { printk(KERN_ERR "clocksource: %s is already registered\n", clock->name); return; } printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n", clock->name, clock->mult, clock->shift); } static int decrementer_set_next_event(unsigned long evt, struct clock_event_device *dev) { __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt); set_dec(evt); /* We may have raced with new irq work */ if (test_irq_work_pending()) set_dec(1); return 0; } static int decrementer_shutdown(struct clock_event_device *dev) { decrementer_set_next_event(decrementer_max, dev); return 0; } static void register_decrementer_clockevent(int cpu) { struct clock_event_device *dec = &per_cpu(decrementers, cpu); *dec = decrementer_clockevent; dec->cpumask = cpumask_of(cpu); clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max); printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n", dec->name, dec->mult, dec->shift, cpu); /* Set values for KVM, see kvm_emulate_dec() */ decrementer_clockevent.mult = dec->mult; decrementer_clockevent.shift = dec->shift; } static void enable_large_decrementer(void) { if (!cpu_has_feature(CPU_FTR_ARCH_300)) return; if (decrementer_max <= DECREMENTER_DEFAULT_MAX) return; /* * If we're running as the hypervisor we need to enable the LD manually * otherwise firmware should have done it for us. */ if (cpu_has_feature(CPU_FTR_HVMODE)) mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD); } static void __init set_decrementer_max(void) { struct device_node *cpu; u32 bits = 32; /* Prior to ISAv3 the decrementer is always 32 bit */ if (!cpu_has_feature(CPU_FTR_ARCH_300)) return; cpu = of_find_node_by_type(NULL, "cpu"); if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) { if (bits > 64 || bits < 32) { pr_warn("time_init: firmware supplied invalid ibm,dec-bits"); bits = 32; } /* calculate the signed maximum given this many bits */ decrementer_max = (1ul << (bits - 1)) - 1; } of_node_put(cpu); pr_info("time_init: %u bit decrementer (max: %llx)\n", bits, decrementer_max); } static void __init init_decrementer_clockevent(void) { register_decrementer_clockevent(smp_processor_id()); } void secondary_cpu_time_init(void) { /* Enable and test the large decrementer for this cpu */ enable_large_decrementer(); /* Start the decrementer on CPUs that have manual control * such as BookE */ start_cpu_decrementer(); /* FIME: Should make unrelatred change to move snapshot_timebase * call here ! */ register_decrementer_clockevent(smp_processor_id()); } /* This function is only called on the boot processor */ void __init time_init(void) { struct div_result res; u64 scale; unsigned shift; if (__USE_RTC()) { /* 601 processor: dec counts down by 128 every 128ns */ ppc_tb_freq = 1000000000; } 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_ticks_per_jiffy = ppc_tb_freq / HZ; tb_ticks_per_sec = ppc_tb_freq; tb_ticks_per_usec = ppc_tb_freq / 1000000; calc_cputime_factors(); /* * 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; /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */ boot_tb = get_tb_or_rtc(); /* 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_update_count = 0; vdso_data->tb_ticks_per_sec = tb_ticks_per_sec; /* initialise and enable the large decrementer (if we have one) */ set_decrementer_max(); enable_large_decrementer(); /* Start the decrementer on CPUs that have manual control * such as BookE */ start_cpu_decrementer(); /* Register the clocksource */ clocksource_init(); init_decrementer_clockevent(); tick_setup_hrtimer_broadcast(); #ifdef CONFIG_COMMON_CLK of_clk_init(NULL); #endif } /* * 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; } /* We don't need to calibrate delay, we use the CPU timebase for that */ void calibrate_delay(void) { /* Some generic code (such as spinlock debug) use loops_per_jiffy * as the number of __delay(1) in a jiffy, so make it so */ loops_per_jiffy = tb_ticks_per_jiffy; } #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC) static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm) { ppc_md.get_rtc_time(tm); return 0; } static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm) { if (!ppc_md.set_rtc_time) return -EOPNOTSUPP; if (ppc_md.set_rtc_time(tm) < 0) return -EOPNOTSUPP; return 0; } static const struct rtc_class_ops rtc_generic_ops = { .read_time = rtc_generic_get_time, .set_time = rtc_generic_set_time, }; static int __init rtc_init(void) { struct platform_device *pdev; if (!ppc_md.get_rtc_time) return -ENODEV; pdev = platform_device_register_data(NULL, "rtc-generic", -1, &rtc_generic_ops, sizeof(rtc_generic_ops)); return PTR_ERR_OR_ZERO(pdev); } device_initcall(rtc_init); #endif