/* * 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/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 <linux/profile.h> #include <asm/io.h>#include <asm/nvram.h>#include <asm/cache.h>#include <asm/8xx_immap.h>#include <asm/machdep.h>#include <asm/irq_regs.h> #include <asm/time.h> unsigned long disarm_decr[NR_CPUS]; extern struct timezone sys_tz; /* keep track of when we need to update the rtc */time_t last_rtc_update; /* 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;unsigned long tb_to_ns_scale; /* used for timezone offset */static long timezone_offset; DEFINE_SPINLOCK(rtc_lock); 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;} #ifdef CONFIG_SMPunsigned 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 void wakeup_decrementer(void){	set_dec(tb_ticks_per_jiffy);	/* No currently-supported powerbook has a 601,	 * so use get_tbl, not native	 */	last_jiffy_stamp(0) = tb_last_stamp = get_tbl();} /* * timer_interrupt - gets called when the decrementer overflows, * with interrupts disabled. * We set it up to overflow again in 1/HZ seconds. */void timer_interrupt(struct pt_regs * regs){	struct pt_regs *old_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); 	old_regs = set_irq_regs(regs);	irq_enter(); 	while ((next_dec = tb_ticks_per_jiffy - tb_delta(&jiffy_stamp)) <= 0) {		jiffy_stamp += tb_ticks_per_jiffy;				profile_tick(CPU_PROFILING);		update_process_times(user_mode(regs)); 	  	if (smp_processor_id())			continue; 		/* We are in an interrupt, no need to save/restore flags */		write_seqlock(&xtime_lock);		tb_last_stamp = jiffy_stamp;		do_timer(1); 		/*		 * 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) {		  	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_sequnlock(&xtime_lock);	}	if ( !disarm_decr[smp_processor_id()] )		set_dec(next_dec);	last_jiffy_stamp(cpu) = jiffy_stamp; 	if (ppc_md.heartbeat && !ppc_md.heartbeat_count--)		ppc_md.heartbeat(); 	irq_exit();	set_irq_regs(old_regs);} /* * This version of gettimeofday has microsecond resolution. */void do_gettimeofday(struct timeval *tv){	unsigned long flags;	unsigned long seq;	unsigned delta, usec, sec; 	do {		seq = read_seqbegin_irqsave(&xtime_lock, flags);		sec = xtime.tv_sec;		usec = (xtime.tv_nsec / 1000);		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 */	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 	usec += mulhwu(tb_to_us, delta);	while (usec >= 1000000) {	  	sec++;		usec -= 1000000;	}	tv->tv_sec = sec;	tv->tv_usec = usec;} EXPORT_SYMBOL(do_gettimeofday); 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;	int 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 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())); 	new_nsec -= 1000 * mulhwu(tb_to_us, tb_delta); 	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();	write_sequnlock_irqrestore(&xtime_lock, flags);	clock_was_set();	return 0;} EXPORT_SYMBOL(do_settimeofday); /* 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();		tb_to_ns_scale = mulhwu(tb_to_us, 1000 << 10);	} 	/* 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_nsec = 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 */        if (timezone_offset) {		sys_tz.tz_minuteswest = -timezone_offset / 60;		sys_tz.tz_dsttime = 0;		xtime.tv_sec -= timezone_offset;        }        set_normalized_timespec(&wall_to_monotonic,                                -xtime.tv_sec, -xtime.tv_nsec);} #define FEBRUARY		2#define	STARTOFTIME		1970#define SECDAY			86400L#define SECYR			(SECDAY * 365) /* * Note: this is wrong for 2100, but our signed 32-bit time_t will * have overflowed long before that, so who cares.  -- paulus */#define	leapyear(year)		((year) % 4 == 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}; 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;} unsigned long long sched_clock(void){	unsigned long lo, hi, hi2;	unsigned long long tb; 	if (!__USE_RTC()) {		do {			hi = get_tbu();			lo = get_tbl();			hi2 = get_tbu();		} while (hi2 != hi);		tb = ((unsigned long long) hi << 32) | lo;		tb = (tb * tb_to_ns_scale) >> 10;	} else {		do {			hi = get_rtcu();			lo = get_rtcl();			hi2 = get_rtcu();		} while (hi2 != hi);		tb = ((unsigned long long) hi) * 1000000000 + lo;	}	return tb;}