diff options
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r-- | arch/powerpc/kernel/time.c | 545 |
1 files changed, 359 insertions, 186 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 1886045a2fd..4a27218a086 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -50,6 +50,8 @@ #include <linux/security.h> #include <linux/percpu.h> #include <linux/rtc.h> +#include <linux/jiffies.h> +#include <linux/posix-timers.h> #include <asm/io.h> #include <asm/processor.h> @@ -97,9 +99,18 @@ 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; -unsigned long processor_freq; + +#define TICKLEN_SCALE (SHIFT_SCALE - 10) +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); @@ -113,10 +124,6 @@ extern unsigned long wall_jiffies; extern struct timezone sys_tz; static long timezone_offset; -void ppc_adjtimex(void); - -static unsigned adjusting_time = 0; - unsigned long ppc_proc_freq; unsigned long ppc_tb_freq; @@ -130,6 +137,224 @@ unsigned long tb_last_stamp; */ DEFINE_PER_CPU(unsigned long, 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_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; @@ -178,8 +403,7 @@ static __inline__ void timer_check_rtc(void) */ 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 && - jiffies - wall_jiffies == 1) { + 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; @@ -226,15 +450,14 @@ void do_gettimeofday(struct timeval *tv) if (__USE_RTC()) { /* do this the old way */ unsigned long flags, seq; - unsigned int sec, nsec, usec, lost; + 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_stamp); - lost = jiffies - wall_jiffies; } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); - usec = nsec / 1000 + lost * (1000000 / HZ); + usec = nsec / 1000; while (usec >= 1000000) { usec -= 1000000; ++sec; @@ -248,23 +471,6 @@ void do_gettimeofday(struct timeval *tv) EXPORT_SYMBOL(do_gettimeofday); -/* Synchronize xtime with do_gettimeofday */ - -static inline void timer_sync_xtime(unsigned long cur_tb) -{ -#ifdef CONFIG_PPC64 - /* why do we do this? */ - struct timeval my_tv; - - __do_gettimeofday(&my_tv, cur_tb); - - if (xtime.tv_sec <= my_tv.tv_sec) { - xtime.tv_sec = my_tv.tv_sec; - xtime.tv_nsec = my_tv.tv_usec * 1000; - } -#endif -} - /* * There are two copies of tb_to_xs and stamp_xsec so that no * lock is needed to access and use these values in @@ -297,9 +503,9 @@ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec, * 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_update_count); - smp_wmb(); vdso_data->tb_orig_stamp = new_tb_stamp; vdso_data->stamp_xsec = new_stamp_xsec; vdso_data->tb_to_xs = new_tb_to_xs; @@ -323,15 +529,40 @@ 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 ((offset & 0x80000000u) == 0) + if (tlen == last_tick_len && offset < 0x80000000u) return; - new_stamp_xsec = do_gtod.varp->stamp_xsec - + mulhdu(offset, do_gtod.varp->tb_to_xs); - update_gtod(cur_tb, new_stamp_xsec, do_gtod.varp->tb_to_xs); + 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 @@ -381,6 +612,7 @@ static void iSeries_tb_recal(void) 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; @@ -429,6 +661,7 @@ void timer_interrupt(struct pt_regs * regs) irq_enter(); profile_tick(CPU_PROFILING, regs); + calculate_steal_time(); #ifdef CONFIG_PPC_ISERIES get_lppaca()->int_dword.fields.decr_int = 0; @@ -450,7 +683,7 @@ void timer_interrupt(struct pt_regs * regs) * is the case. */ if (!cpu_is_offline(cpu)) - update_process_times(user_mode(regs)); + account_process_time(regs); /* * No need to check whether cpu is offline here; boot_cpuid @@ -462,13 +695,10 @@ void timer_interrupt(struct pt_regs * regs) write_seqlock(&xtime_lock); tb_last_jiffy += tb_ticks_per_jiffy; tb_last_stamp = per_cpu(last_jiffy, cpu); - timer_recalc_offset(tb_last_jiffy); do_timer(regs); - timer_sync_xtime(tb_last_jiffy); + timer_recalc_offset(tb_last_jiffy); timer_check_rtc(); write_sequnlock(&xtime_lock); - if (adjusting_time && (time_adjust == 0)) - ppc_adjtimex(); } next_dec = tb_ticks_per_jiffy - ticks; @@ -492,29 +722,45 @@ void timer_interrupt(struct pt_regs * regs) void wakeup_decrementer(void) { - int i; + unsigned long ticks; - set_dec(tb_ticks_per_jiffy); /* - * We don't expect this to be called on a machine with a 601, - * so using get_tbl is fine. + * The timebase gets saved on sleep and restored on wakeup, + * so all we need to do is to reset the decrementer. */ - tb_last_stamp = tb_last_jiffy = get_tb(); - for_each_cpu(i) - per_cpu(last_jiffy, i) = tb_last_stamp; + 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; unsigned long 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_cpu(i) { - if (i != boot_cpuid) { + 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; } @@ -541,8 +787,8 @@ 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; - long int tb_delta; - u64 new_xsec, tb_delta_xs; + u64 new_xsec; + unsigned long tb_delta; if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) return -EINVAL; @@ -563,9 +809,23 @@ int do_settimeofday(struct timespec *tv) 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_stamp); - tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy; - tb_delta_xs = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); + 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); @@ -580,12 +840,12 @@ int do_settimeofday(struct timespec *tv) ntp_clear(); - new_xsec = 0; - if (new_nsec != 0) { - new_xsec = (u64)new_nsec * XSEC_PER_SEC; + new_xsec = xtime.tv_nsec; + if (new_xsec != 0) { + new_xsec *= XSEC_PER_SEC; do_div(new_xsec, NSEC_PER_SEC); } - new_xsec += (u64)new_sec * XSEC_PER_SEC - tb_delta_xs; + 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; @@ -671,7 +931,7 @@ void __init time_init(void) unsigned long flags; unsigned long tm = 0; struct div_result res; - u64 scale; + u64 scale, x; unsigned shift; if (ppc_md.time_init != NULL) @@ -693,11 +953,43 @@ void __init time_init(void) } tb_ticks_per_jiffy = ppc_tb_freq / HZ; - tb_ticks_per_sec = tb_ticks_per_jiffy * 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); - div128_by_32(1024*1024, 0, tb_ticks_per_sec, &res); - tb_to_xs = res.result_low; + 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. @@ -724,6 +1016,14 @@ void __init time_init(void) 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]; @@ -738,18 +1038,11 @@ void __init time_init(void) 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 = xtime.tv_sec * XSEC_PER_SEC; + vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC; vdso_data->tb_to_xs = tb_to_xs; time_freq = 0; - /* 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; - xtime.tv_sec -= timezone_offset; - } - last_rtc_update = xtime.tv_sec; set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); @@ -759,126 +1052,6 @@ void __init time_init(void) set_dec(tb_ticks_per_jiffy); } -/* - * After adjtimex is called, adjust the conversion of tb ticks - * to microseconds to keep do_gettimeofday synchronized - * with ntpd. - * - * Use the time_adjust, time_freq and time_offset computed by adjtimex to - * adjust the frequency. - */ - -/* #define DEBUG_PPC_ADJTIMEX 1 */ - -void ppc_adjtimex(void) -{ -#ifdef CONFIG_PPC64 - unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec, - new_tb_to_xs, new_xsec, new_stamp_xsec; - unsigned long tb_ticks_per_sec_delta; - long delta_freq, ltemp; - struct div_result divres; - unsigned long flags; - long singleshot_ppm = 0; - - /* - * Compute parts per million frequency adjustment to - * accomplish the time adjustment implied by time_offset to be - * applied over the elapsed time indicated by time_constant. - * Use SHIFT_USEC to get it into the same units as - * time_freq. - */ - if ( time_offset < 0 ) { - ltemp = -time_offset; - ltemp <<= SHIFT_USEC - SHIFT_UPDATE; - ltemp >>= SHIFT_KG + time_constant; - ltemp = -ltemp; - } else { - ltemp = time_offset; - ltemp <<= SHIFT_USEC - SHIFT_UPDATE; - ltemp >>= SHIFT_KG + time_constant; - } - - /* If there is a single shot time adjustment in progress */ - if ( time_adjust ) { -#ifdef DEBUG_PPC_ADJTIMEX - printk("ppc_adjtimex: "); - if ( adjusting_time == 0 ) - printk("starting "); - printk("single shot time_adjust = %ld\n", time_adjust); -#endif - - adjusting_time = 1; - - /* - * Compute parts per million frequency adjustment - * to match time_adjust - */ - singleshot_ppm = tickadj * HZ; - /* - * The adjustment should be tickadj*HZ to match the code in - * linux/kernel/timer.c, but experiments show that this is too - * large. 3/4 of tickadj*HZ seems about right - */ - singleshot_ppm -= singleshot_ppm / 4; - /* Use SHIFT_USEC to get it into the same units as time_freq */ - singleshot_ppm <<= SHIFT_USEC; - if ( time_adjust < 0 ) - singleshot_ppm = -singleshot_ppm; - } - else { -#ifdef DEBUG_PPC_ADJTIMEX - if ( adjusting_time ) - printk("ppc_adjtimex: ending single shot time_adjust\n"); -#endif - adjusting_time = 0; - } - - /* Add up all of the frequency adjustments */ - delta_freq = time_freq + ltemp + singleshot_ppm; - - /* - * Compute a new value for tb_ticks_per_sec based on - * the frequency adjustment - */ - den = 1000000 * (1 << (SHIFT_USEC - 8)); - if ( delta_freq < 0 ) { - tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den; - new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta; - } - else { - tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den; - new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta; - } - -#ifdef DEBUG_PPC_ADJTIMEX - printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm); - printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec); -#endif - - /* - * Compute a new value of tb_to_xs (used to convert tb to - * microseconds) and a new value of stamp_xsec which is the - * time (in 1/2^20 second units) corresponding to - * tb_orig_stamp. This new value of stamp_xsec compensates - * for the change in frequency (implied by the new tb_to_xs) - * which guarantees that the current time remains the same. - */ - write_seqlock_irqsave( &xtime_lock, flags ); - tb_ticks = get_tb() - do_gtod.varp->tb_orig_stamp; - div128_by_32(1024*1024, 0, new_tb_ticks_per_sec, &divres); - new_tb_to_xs = divres.result_low; - new_xsec = mulhdu(tb_ticks, new_tb_to_xs); - - old_xsec = mulhdu(tb_ticks, do_gtod.varp->tb_to_xs); - new_stamp_xsec = do_gtod.varp->stamp_xsec + old_xsec - new_xsec; - - update_gtod(do_gtod.varp->tb_orig_stamp, new_stamp_xsec, new_tb_to_xs); - - write_sequnlock_irqrestore( &xtime_lock, flags ); -#endif /* CONFIG_PPC64 */ -} - #define FEBRUARY 2 #define STARTOFTIME 1970 |