| /* |
| * 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). |
| * |
| * 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). |
| * |
| * TODO (not necessarily in this file): |
| * - improve precision and reproducibility of timebase frequency |
| * measurement at boot time. |
| * - get rid of xtime_lock for gettimeofday (generic kernel problem |
| * to be implemented on all architectures for SMP scalability and |
| * eventually implementing gettimeofday without entering the kernel). |
| * - put all time/clock related variables in a single structure |
| * to minimize number of cache lines touched by gettimeofday() |
| * - 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. |
| * |
| * |
| * The following comment is partially obsolete (at least the long wait |
| * is no more a valid reason): |
| * Since the MPC8xx has a programmable interrupt timer, I decided to |
| * use that rather than the decrementer. Two reasons: 1.) the clock |
| * frequency is low, causing 2.) a long wait in the timer interrupt |
| * while ((d = get_dec()) == dval) |
| * loop. The MPC8xx can be driven from a variety of input clocks, |
| * so a number of assumptions have been made here because the kernel |
| * parameter HZ is a constant. We assume (correctly, today :-) that |
| * the MPC8xx on the MBX board is driven from a 32.768 kHz crystal. |
| * This is then divided by 4, providing a 8192 Hz clock into the PIT. |
| * Since it is not possible to get a nice 100 Hz clock out of this, without |
| * creating a software PLL, I have set HZ to 128. -- Dan |
| * |
| * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 |
| * "A Kernel Model for Precision Timekeeping" by Dave Mills |
| */ |
| |
| #include <linux/config.h> |
| #include <linux/errno.h> |
| #include <linux/sched.h> |
| #include <linux/kernel.h> |
| #include <linux/param.h> |
| #include <linux/string.h> |
| #include <linux/mm.h> |
| #include <linux/module.h> |
| #include <linux/interrupt.h> |
| #include <linux/timex.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/mc146818rtc.h> |
| #include <linux/time.h> |
| #include <linux/init.h> |
| |
| #include <asm/segment.h> |
| #include <asm/io.h> |
| #include <asm/processor.h> |
| #include <asm/nvram.h> |
| #include <asm/cache.h> |
| #include <asm/8xx_immap.h> |
| #include <asm/machdep.h> |
| |
| #include <asm/time.h> |
| |
| unsigned long disarm_decr[NR_CPUS]; |
| |
| extern int do_sys_settimeofday(struct timeval *tv, struct timezone *tz); |
| |
| /* keep track of when we need to update the rtc */ |
| time_t last_rtc_update; |
| extern rwlock_t xtime_lock; |
| |
| /* The decrementer counts down by 128 every 128ns on a 601. */ |
| #define DECREMENTER_COUNT_601 (1000000000 / HZ) |
| |
| unsigned tb_ticks_per_jiffy; |
| unsigned tb_to_us; |
| unsigned tb_last_stamp; |
| |
| extern unsigned long wall_jiffies; |
| |
| static long timezone_offset; |
| |
| spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED; |
| |
| EXPORT_SYMBOL(rtc_lock); |
| |
| /* Timer interrupt helper function */ |
| static inline int tb_delta(unsigned *jiffy_stamp) { |
| int delta; |
| if (__USE_RTC()) { |
| delta = get_rtcl(); |
| if (delta < *jiffy_stamp) *jiffy_stamp -= 1000000000; |
| delta -= *jiffy_stamp; |
| } else { |
| delta = get_tbl() - *jiffy_stamp; |
| } |
| return delta; |
| } |
| |
| extern unsigned long prof_cpu_mask; |
| extern unsigned int * prof_buffer; |
| extern unsigned long prof_len; |
| extern unsigned long prof_shift; |
| extern char _stext; |
| |
| static inline void ppc_do_profile (unsigned long nip) |
| { |
| if (!prof_buffer) |
| return; |
| |
| /* |
| * Only measure the CPUs specified by /proc/irq/prof_cpu_mask. |
| * (default is all CPUs.) |
| */ |
| if (!((1<<smp_processor_id()) & prof_cpu_mask)) |
| return; |
| |
| nip -= (unsigned long) &_stext; |
| nip >>= prof_shift; |
| /* |
| * Don't ignore out-of-bounds EIP values silently, |
| * put them into the last histogram slot, so if |
| * present, they will show up as a sharp peak. |
| */ |
| if (nip > prof_len-1) |
| nip = prof_len-1; |
| atomic_inc((atomic_t *)&prof_buffer[nip]); |
| } |
| |
| /* |
| * timer_interrupt - gets called when the decrementer overflows, |
| * with interrupts disabled. |
| * We set it up to overflow again in 1/HZ seconds. |
| */ |
| int timer_interrupt(struct pt_regs * regs) |
| { |
| int next_dec; |
| unsigned long cpu = smp_processor_id(); |
| unsigned jiffy_stamp = last_jiffy_stamp(cpu); |
| extern void do_IRQ(struct pt_regs *); |
| |
| if (atomic_read(&ppc_n_lost_interrupts) != 0) |
| do_IRQ(regs); |
| |
| hardirq_enter(cpu); |
| |
| while ((next_dec = tb_ticks_per_jiffy - tb_delta(&jiffy_stamp)) <= 0) { |
| jiffy_stamp += tb_ticks_per_jiffy; |
| if (!user_mode(regs)) |
| ppc_do_profile(instruction_pointer(regs)); |
| if (unlikely(!heartbeat_count(cpu)--) |
| && heartbeat_reset(cpu)) { |
| ppc_md.heartbeat(); |
| heartbeat_count(cpu) = heartbeat_reset(cpu); |
| } |
| if (cpu) |
| continue; |
| |
| /* We are in an interrupt, no need to save/restore flags */ |
| write_lock(&xtime_lock); |
| tb_last_stamp = jiffy_stamp; |
| do_timer(regs); |
| |
| /* |
| * 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 && (time_status & STA_UNSYNC) == 0 && |
| xtime.tv_sec - last_rtc_update >= 659 && |
| abs(xtime.tv_usec - (1000000-1000000/HZ)) < 500000/HZ && |
| jiffies - wall_jiffies == 1) { |
| if (ppc_md.set_rtc_time(xtime.tv_sec+1 + timezone_offset) == 0) |
| last_rtc_update = xtime.tv_sec+1; |
| else |
| /* Try again one minute later */ |
| last_rtc_update += 60; |
| } |
| write_unlock(&xtime_lock); |
| } |
| if (!disarm_decr[cpu]) |
| set_dec(next_dec); |
| last_jiffy_stamp(cpu) = jiffy_stamp; |
| |
| #ifdef CONFIG_SMP |
| smp_local_timer_interrupt(regs); |
| #endif /* CONFIG_SMP */ |
| |
| hardirq_exit(cpu); |
| |
| if (softirq_pending(cpu)) |
| do_softirq(); |
| |
| return 1; /* lets ret_from_int know we can do checks */ |
| } |
| |
| /* |
| * This version of gettimeofday has microsecond resolution. |
| */ |
| void do_gettimeofday(struct timeval *tv) |
| { |
| unsigned long flags; |
| unsigned delta, lost_ticks, usec, sec; |
| |
| read_lock_irqsave(&xtime_lock, flags); |
| sec = xtime.tv_sec; |
| usec = xtime.tv_usec; |
| delta = tb_ticks_since(tb_last_stamp); |
| #ifdef CONFIG_SMP |
| /* As long as timebases are not in sync, gettimeofday can only |
| * have jiffy resolution on SMP. |
| */ |
| if (!smp_tb_synchronized) |
| delta = 0; |
| #endif /* CONFIG_SMP */ |
| lost_ticks = jiffies - wall_jiffies; |
| read_unlock_irqrestore(&xtime_lock, flags); |
| |
| usec += mulhwu(tb_to_us, tb_ticks_per_jiffy * lost_ticks + delta); |
| while (usec >= 1000000) { |
| sec++; |
| usec -= 1000000; |
| } |
| tv->tv_sec = sec; |
| tv->tv_usec = usec; |
| } |
| |
| void do_settimeofday(struct timeval *tv) |
| { |
| unsigned long flags; |
| int tb_delta, new_usec, new_sec; |
| |
| write_lock_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 update after STA_UNSYNC |
| * is cleared. Tool 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. Note also that |
| * we don't touch the decrementer since: |
| * a) it would lose timer interrupt synchronization on SMP |
| * (if it is working one day) |
| * b) it could make one jiffy spuriously shorter or longer |
| * which would introduce another source of uncertainty potentially |
| * harmful to relatively short timers. |
| */ |
| |
| /* This works perfectly on SMP only if the tb are in sync but |
| * guarantees an error < 1 jiffy even if they are off by eons, |
| * still reasonable when gettimeofday resolution is 1 jiffy. |
| */ |
| tb_delta = tb_ticks_since(last_jiffy_stamp(smp_processor_id())); |
| tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy; |
| new_sec = tv->tv_sec; |
| new_usec = tv->tv_usec - mulhwu(tb_to_us, tb_delta); |
| while (new_usec <0) { |
| new_sec--; |
| new_usec += 1000000; |
| } |
| xtime.tv_usec = new_usec; |
| xtime.tv_sec = new_sec; |
| |
| /* 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; |
| |
| time_adjust = 0; /* stop active adjtime() */ |
| time_status |= STA_UNSYNC; |
| time_state = TIME_ERROR; /* p. 24, (a) */ |
| time_maxerror = NTP_PHASE_LIMIT; |
| time_esterror = NTP_PHASE_LIMIT; |
| write_unlock_irqrestore(&xtime_lock, flags); |
| } |
| |
| /* This function is only called on the boot processor */ |
| void __init time_init(void) |
| { |
| time_t sec, old_sec; |
| unsigned old_stamp, stamp, elapsed; |
| |
| if (ppc_md.time_init != NULL) |
| timezone_offset = ppc_md.time_init(); |
| |
| if (__USE_RTC()) { |
| /* 601 processor: dec counts down by 128 every 128ns */ |
| tb_ticks_per_jiffy = DECREMENTER_COUNT_601; |
| /* mulhwu_scale_factor(1000000000, 1000000) is 0x418937 */ |
| tb_to_us = 0x418937; |
| } else { |
| ppc_md.calibrate_decr(); |
| } |
| |
| /* Now that the decrementer is calibrated, it can be used in case the |
| * clock is stuck, but the fact that we have to handle the 601 |
| * makes things more complex. Repeatedly read the RTC until the |
| * next second boundary to try to achieve some precision. If there |
| * is no RTC, we still need to set tb_last_stamp and |
| * last_jiffy_stamp(cpu 0) to the current stamp. |
| */ |
| stamp = get_native_tbl(); |
| if (ppc_md.get_rtc_time) { |
| sec = ppc_md.get_rtc_time(); |
| elapsed = 0; |
| do { |
| old_stamp = stamp; |
| old_sec = sec; |
| stamp = get_native_tbl(); |
| if (__USE_RTC() && stamp < old_stamp) |
| old_stamp -= 1000000000; |
| elapsed += stamp - old_stamp; |
| sec = ppc_md.get_rtc_time(); |
| } while ( sec == old_sec && elapsed < 2*HZ*tb_ticks_per_jiffy); |
| if (sec == old_sec) |
| printk("Warning: real time clock seems stuck!\n"); |
| xtime.tv_sec = sec; |
| xtime.tv_usec = 0; |
| /* No update now, we just read the time from the RTC ! */ |
| last_rtc_update = xtime.tv_sec; |
| } |
| |
| last_jiffy_stamp(0) = tb_last_stamp = stamp; |
| |
| /* Not exact, but the timer interrupt takes care of this */ |
| set_dec(tb_ticks_per_jiffy); |
| |
| /* If platform provided a timezone (pmac), we correct the time |
| * using do_sys_settimeofday() which in turn calls warp_clock() |
| */ |
| if (timezone_offset) { |
| struct timezone tz; |
| tz.tz_minuteswest = -timezone_offset / 60; |
| tz.tz_dsttime = 0; |
| do_sys_settimeofday(NULL, &tz); |
| } |
| } |
| |
| #define FEBRUARY 2 |
| #define STARTOFTIME 1970 |
| #define SECDAY 86400L |
| #define SECYR (SECDAY * 365) |
| #define leapyear(y) ((!(y % 4) && (y % 100)) || !(y % 400)) |
| #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 |
| }; |
| |
| void to_tm(int tim, struct rtc_time * tm) |
| { |
| register int i; |
| register long hms, day, gday; |
| |
| gday = 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. Jan. 1, 1970 was a Thursday. |
| */ |
| tm->tm_wday = (gday + 4) % 7; |
| } |
| |
| /* 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; |
| } |
| |