/* *  linux/arch/parisc/kernel/time.c * *  Copyright (C) 1991, 1992, 1995  Linus Torvalds *  Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King *  Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org) * * 1994-07-02  Alan Modra *             fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime * 1998-12-20  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/module.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/param.h>#include <linux/string.h>#include <linux/mm.h>#include <linux/interrupt.h>#include <linux/time.h>#include <linux/init.h>#include <linux/smp.h>#include <linux/profile.h> #include <asm/uaccess.h>#include <asm/io.h>#include <asm/irq.h>#include <asm/param.h>#include <asm/pdc.h>#include <asm/led.h> #include <linux/timex.h> /* xtime and wall_jiffies keep wall-clock time */extern unsigned long wall_jiffies; static long clocktick __read_mostly;	/* timer cycles per tick */static long halftick __read_mostly; #ifdef CONFIG_SMPextern void smp_do_timer(struct pt_regs *regs);#endif irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs){	long now;	long next_tick;	int nticks;	int cpu = smp_processor_id(); 	profile_tick(CPU_PROFILING, regs); 	now = mfctl(16);	/* initialize next_tick to time at last clocktick */	next_tick = cpu_data[cpu].it_value; 	/* since time passes between the interrupt and the mfctl()	 * above, it is never true that last_tick + clocktick == now.  If we	 * never miss a clocktick, we could set next_tick = last_tick + clocktick	 * but maybe we'll miss ticks, hence the loop.	 *	 * Variables are *signed*.	 */ 	nticks = 0;	while((next_tick - now) < halftick) {		next_tick += clocktick;		nticks++;	}	mtctl(next_tick, 16);	cpu_data[cpu].it_value = next_tick; 	while (nticks--) {#ifdef CONFIG_SMP		smp_do_timer(regs);#else		update_process_times(user_mode(regs));#endif		if (cpu == 0) {			write_seqlock(&xtime_lock);			do_timer(regs);			write_sequnlock(&xtime_lock);		}	}    	/* check soft power switch status */	if (cpu == 0 && !atomic_read(&power_tasklet.count))		tasklet_schedule(&power_tasklet); 	return IRQ_HANDLED;}  unsigned long profile_pc(struct pt_regs *regs){	unsigned long pc = instruction_pointer(regs); 	if (regs->gr[0] & PSW_N)		pc -= 4; #ifdef CONFIG_SMP	if (in_lock_functions(pc))		pc = regs->gr[2];#endif 	return pc;}EXPORT_SYMBOL(profile_pc);  /*** converted from ia64 ***//* * Return the number of micro-seconds that elapsed since the last * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock * must be at least read-locked when calling this routine. */static inline unsigned longgettimeoffset (void){#ifndef CONFIG_SMP	/*	 * FIXME: This won't work on smp because jiffies are updated by cpu 0.	 *    Once parisc-linux learns the cr16 difference between processors,	 *    this could be made to work.	 */	long last_tick;	long elapsed_cycles; 	/* it_value is the intended time of the next tick */	last_tick = cpu_data[smp_processor_id()].it_value; 	/* Subtract one tick and account for possible difference between	 * when we expected the tick and when it actually arrived.	 * (aka wall vs real)	 */	last_tick -= clocktick * (jiffies - wall_jiffies + 1);	elapsed_cycles = mfctl(16) - last_tick; 	/* the precision of this math could be improved */	return elapsed_cycles / (PAGE0->mem_10msec / 10000);#else	return 0;#endif} voiddo_gettimeofday (struct timeval *tv){	unsigned long flags, seq, usec, sec; 	do {		seq = read_seqbegin_irqsave(&xtime_lock, flags);		usec = gettimeoffset();		sec = xtime.tv_sec;		usec += (xtime.tv_nsec / 1000);	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 	while (usec >= 1000000) {		usec -= 1000000;		++sec;	} 	tv->tv_sec = sec;	tv->tv_usec = usec;} EXPORT_SYMBOL(do_gettimeofday); intdo_settimeofday (struct timespec *tv){	time_t wtm_sec, sec = tv->tv_sec;	long wtm_nsec, nsec = tv->tv_nsec; 	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)		return -EINVAL; 	write_seqlock_irq(&xtime_lock);	{		/*		 * This is revolting. We need to set "xtime"		 * correctly. However, the value in this location is		 * the value at the most recent update of wall time.		 * Discover what correction gettimeofday would have		 * done, and then undo it!		 */		nsec -= gettimeoffset() * 1000; 		wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);		wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 		set_normalized_timespec(&xtime, sec, nsec);		set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); 		ntp_clear();	}	write_sequnlock_irq(&xtime_lock);	clock_was_set();	return 0;}EXPORT_SYMBOL(do_settimeofday); /* * XXX: We can do better than this. * Returns nanoseconds */ unsigned long long sched_clock(void){	return (unsigned long long)jiffies * (1000000000 / HZ);}  void __init time_init(void){	unsigned long next_tick;	static struct pdc_tod tod_data; 	clocktick = (100 * PAGE0->mem_10msec) / HZ;	halftick = clocktick / 2; 	/* Setup clock interrupt timing */ 	next_tick = mfctl(16);	next_tick += clocktick;	cpu_data[smp_processor_id()].it_value = next_tick; 	/* kick off Itimer (CR16) */	mtctl(next_tick, 16); 	if(pdc_tod_read(&tod_data) == 0) {		write_seqlock_irq(&xtime_lock);		xtime.tv_sec = tod_data.tod_sec;		xtime.tv_nsec = tod_data.tod_usec * 1000;		set_normalized_timespec(&wall_to_monotonic,		                        -xtime.tv_sec, -xtime.tv_nsec);		write_sequnlock_irq(&xtime_lock);	} else {		printk(KERN_ERR "Error reading tod clock\n");	        xtime.tv_sec = 0;		xtime.tv_nsec = 0;	}}