Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 827 insertions, 0 deletions

diff --git a/arch/ppc64/kernel/time.c b/arch/ppc64/kernel/time.c
new file mode 100644
index 00000000000..77ded5a363b
--- /dev/null
+++ b/arch/ppc64/kernel/time.c
@@ -0,0 +1,827 @@
+/*
+ * 
+ * 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 iSeries, we calibrate the timebase
+ * against the Titan chip's clock.)
+ * - 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
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#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/timex.h>
+#include <linux/kernel_stat.h>
+#include <linux/mc146818rtc.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/profile.h>
+#include <linux/cpu.h>
+#include <linux/security.h>
+
+#include <asm/segment.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/nvram.h>
+#include <asm/cache.h>
+#include <asm/machdep.h>
+#ifdef CONFIG_PPC_ISERIES
+#include <asm/iSeries/ItLpQueue.h>
+#include <asm/iSeries/HvCallXm.h>
+#endif
+#include <asm/uaccess.h>
+#include <asm/time.h>
+#include <asm/ppcdebug.h>
+#include <asm/prom.h>
+#include <asm/sections.h>
+#include <asm/systemcfg.h>
+
+u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
+
+EXPORT_SYMBOL(jiffies_64);
+
+/* keep track of when we need to update the rtc */
+time_t last_rtc_update;
+extern int piranha_simulator;
+#ifdef CONFIG_PPC_ISERIES
+unsigned long iSeries_recal_titan = 0;
+unsigned long iSeries_recal_tb = 0; 
+static unsigned long first_settimeofday = 1;
+#endif
+
+#define XSEC_PER_SEC (1024*1024)
+
+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;
+unsigned long tb_to_xs;
+unsigned      tb_to_us;
+unsigned long processor_freq;
+DEFINE_SPINLOCK(rtc_lock);
+
+unsigned long tb_to_ns_scale;
+unsigned long tb_to_ns_shift;
+
+struct gettimeofday_struct do_gtod;
+
+extern unsigned long wall_jiffies;
+extern unsigned long lpevent_count;
+extern int smp_tb_synchronized;
+
+extern struct timezone sys_tz;
+
+void ppc_adjtimex(void);
+
+static unsigned adjusting_time = 0;
+
+static __inline__ void timer_check_rtc(void)
+{
+        /*
+         * 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 ( (time_status & STA_UNSYNC) == 0 &&
+             xtime.tv_sec - last_rtc_update >= 659 &&
+             abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ &&
+             jiffies - wall_jiffies == 1) {
+	    struct rtc_time tm;
+	    to_tm(xtime.tv_sec+1, &tm);
+	    tm.tm_year -= 1900;
+	    tm.tm_mon -= 1;
+            if (ppc_md.set_rtc_time(&tm) == 0)
+                last_rtc_update = xtime.tv_sec+1;
+            else
+                /* Try again one minute later */
+                last_rtc_update += 60;
+        }
+}
+
+/*
+ * This version of gettimeofday has microsecond resolution.
+ */
+static inline void __do_gettimeofday(struct timeval *tv, unsigned long tb_val)
+{
+	unsigned long sec, usec, tb_ticks;
+	unsigned long xsec, tb_xsec;
+	struct gettimeofday_vars * temp_varp;
+	unsigned long temp_tb_to_xs, temp_stamp_xsec;
+
+	/*
+	 * These calculations are faster (gets rid of divides)
+	 * if done in units of 1/2^20 rather than microseconds.
+	 * The conversion to microseconds at the end is done
+	 * without a divide (and in fact, without a multiply)
+	 */
+	temp_varp = do_gtod.varp;
+	tb_ticks = tb_val - temp_varp->tb_orig_stamp;
+	temp_tb_to_xs = temp_varp->tb_to_xs;
+	temp_stamp_xsec = temp_varp->stamp_xsec;
+	tb_xsec = mulhdu( tb_ticks, temp_tb_to_xs );
+	xsec = temp_stamp_xsec + tb_xsec;
+	sec = xsec / XSEC_PER_SEC;
+	xsec -= sec * XSEC_PER_SEC;
+	usec = (xsec * USEC_PER_SEC)/XSEC_PER_SEC;
+
+	tv->tv_sec = sec;
+	tv->tv_usec = usec;
+}
+
+void do_gettimeofday(struct timeval *tv)
+{
+	__do_gettimeofday(tv, get_tb());
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+/* Synchronize xtime with do_gettimeofday */ 
+
+static inline void timer_sync_xtime(unsigned long cur_tb)
+{
+	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;
+	}
+}
+
+/*
+ * When the timebase - tb_orig_stamp gets too big, we do a manipulation
+ * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
+ * difference tb - tb_orig_stamp small enough to always fit inside a
+ * 32 bits number. This is a requirement of our fast 32 bits userland
+ * implementation in the vdso. If we "miss" a call to this function
+ * (interrupt latency, CPU locked in a spinlock, ...) and we end up
+ * with a too big difference, then the vdso will fallback to calling
+ * the syscall
+ */
+static __inline__ void timer_recalc_offset(unsigned long cur_tb)
+{
+	struct gettimeofday_vars * temp_varp;
+	unsigned temp_idx;
+	unsigned long offset, new_stamp_xsec, new_tb_orig_stamp;
+
+	if (((cur_tb - do_gtod.varp->tb_orig_stamp) & 0x80000000u) == 0)
+		return;
+
+	temp_idx = (do_gtod.var_idx == 0);
+	temp_varp = &do_gtod.vars[temp_idx];
+
+	new_tb_orig_stamp = cur_tb;
+	offset = new_tb_orig_stamp - do_gtod.varp->tb_orig_stamp;
+	new_stamp_xsec = do_gtod.varp->stamp_xsec + mulhdu(offset, do_gtod.varp->tb_to_xs);
+
+	temp_varp->tb_to_xs = do_gtod.varp->tb_to_xs;
+	temp_varp->tb_orig_stamp = new_tb_orig_stamp;
+	temp_varp->stamp_xsec = new_stamp_xsec;
+	mb();
+	do_gtod.varp = temp_varp;
+	do_gtod.var_idx = temp_idx;
+
+	++(systemcfg->tb_update_count);
+	wmb();
+	systemcfg->tb_orig_stamp = new_tb_orig_stamp;
+	systemcfg->stamp_xsec = new_stamp_xsec;
+	wmb();
+	++(systemcfg->tb_update_count);
+}
+
+#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_PPC_ISERIES
+
+/* 
+ * This function recalibrates the timebase based on the 49-bit time-of-day
+ * value in the Titan chip.  The Titan is much more accurate than the value
+ * returned by the service processor for the timebase frequency.  
+ */
+
+static void iSeries_tb_recal(void)
+{
+	struct div_result divres;
+	unsigned long titan, tb;
+	tb = get_tb();
+	titan = HvCallXm_loadTod();
+	if ( iSeries_recal_titan ) {
+		unsigned long tb_ticks = tb - iSeries_recal_tb;
+		unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
+		unsigned long new_tb_ticks_per_sec   = (tb_ticks * USEC_PER_SEC)/titan_usec;
+		unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
+		long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
+		char sign = '+';		
+		/* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
+		new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
+
+		if ( tick_diff < 0 ) {
+			tick_diff = -tick_diff;
+			sign = '-';
+		}
+		if ( tick_diff ) {
+			if ( tick_diff < tb_ticks_per_jiffy/25 ) {
+				printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
+						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;
+				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;
+				do_gtod.varp->tb_to_xs = tb_to_xs;
+				systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
+				systemcfg->tb_to_xs = tb_to_xs;
+			}
+			else {
+				printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
+					"                   new tb_ticks_per_jiffy = %lu\n"
+					"                   old tb_ticks_per_jiffy = %lu\n",
+					new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
+			}
+		}
+	}
+	iSeries_recal_titan = titan;
+	iSeries_recal_tb = tb;
+}
+#endif
+
+/*
+ * For iSeries shared processors, we have to let the hypervisor
+ * set the hardware decrementer.  We set a virtual decrementer
+ * in the lppaca and call the hypervisor if the virtual
+ * decrementer is less than the current value in the hardware
+ * decrementer. (almost always the new decrementer value will
+ * be greater than the current hardware decementer so the hypervisor
+ * call will not be needed)
+ */
+
+unsigned long tb_last_stamp __cacheline_aligned_in_smp;
+
+/*
+ * timer_interrupt - gets called when the decrementer overflows,
+ * with interrupts disabled.
+ */
+int timer_interrupt(struct pt_regs * regs)
+{
+	int next_dec;
+	unsigned long cur_tb;
+	struct paca_struct *lpaca = get_paca();
+	unsigned long cpu = smp_processor_id();
+
+	irq_enter();
+
+#ifndef CONFIG_PPC_ISERIES
+	profile_tick(CPU_PROFILING, regs);
+#endif
+
+	lpaca->lppaca.int_dword.fields.decr_int = 0;
+
+	while (lpaca->next_jiffy_update_tb <= (cur_tb = get_tb())) {
+		/*
+		 * We cannot disable the decrementer, so in the period
+		 * between this cpu's being marked offline in cpu_online_map
+		 * and calling stop-self, it is taking timer interrupts.
+		 * Avoid calling into the scheduler rebalancing code if this
+		 * is the case.
+		 */
+		if (!cpu_is_offline(cpu))
+			update_process_times(user_mode(regs));
+		/*
+		 * No need to check whether cpu is offline here; boot_cpuid
+		 * should have been fixed up by now.
+		 */
+		if (cpu == boot_cpuid) {
+			write_seqlock(&xtime_lock);
+			tb_last_stamp = lpaca->next_jiffy_update_tb;
+			timer_recalc_offset(lpaca->next_jiffy_update_tb);
+			do_timer(regs);
+			timer_sync_xtime(lpaca->next_jiffy_update_tb);
+			timer_check_rtc();
+			write_sequnlock(&xtime_lock);
+			if ( adjusting_time && (time_adjust == 0) )
+				ppc_adjtimex();
+		}
+		lpaca->next_jiffy_update_tb += tb_ticks_per_jiffy;
+	}
+	
+	next_dec = lpaca->next_jiffy_update_tb - cur_tb;
+	if (next_dec > lpaca->default_decr)
+        	next_dec = lpaca->default_decr;
+	set_dec(next_dec);
+
+#ifdef CONFIG_PPC_ISERIES
+	{
+		struct ItLpQueue *lpq = lpaca->lpqueue_ptr;
+		if (lpq && ItLpQueue_isLpIntPending(lpq))
+			lpevent_count += ItLpQueue_process(lpq, regs);
+	}
+#endif
+
+/* collect purr register values often, for accurate calculations */
+#if defined(CONFIG_PPC_PSERIES)
+	if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
+		struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
+		cu->current_tb = mfspr(SPRN_PURR);
+	}
+#endif
+
+	irq_exit();
+
+	return 1;
+}
+
+/*
+ * 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.
+ */
+unsigned long long sched_clock(void)
+{
+	return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
+}
+
+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;
+	unsigned long delta_xsec;
+	long int tb_delta;
+	unsigned long new_xsec;
+
+	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.
+	 */
+#ifdef CONFIG_PPC_ISERIES
+	if ( first_settimeofday ) {
+		iSeries_tb_recal();
+		first_settimeofday = 0;
+	}
+#endif
+	tb_delta = tb_ticks_since(tb_last_stamp);
+	tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;
+
+	new_nsec -= tb_delta / tb_ticks_per_usec / 1000;
+
+	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;
+
+	time_adjust = 0;                /* stop active adjtime() */
+	time_status |= STA_UNSYNC;
+	time_maxerror = NTP_PHASE_LIMIT;
+	time_esterror = NTP_PHASE_LIMIT;
+
+	delta_xsec = mulhdu( (tb_last_stamp-do_gtod.varp->tb_orig_stamp),
+			     do_gtod.varp->tb_to_xs );
+
+	new_xsec = (new_nsec * XSEC_PER_SEC) / NSEC_PER_SEC;
+	new_xsec += new_sec * XSEC_PER_SEC;
+	if ( new_xsec > delta_xsec ) {
+		do_gtod.varp->stamp_xsec = new_xsec - delta_xsec;
+		systemcfg->stamp_xsec = new_xsec - delta_xsec;
+	}
+	else {
+		/* This is only for the case where the user is setting the time
+		 * way back to a time such that the boot time would have been
+		 * before 1970 ... eg. we booted ten days ago, and we are setting
+		 * the time to Jan 5, 1970 */
+		do_gtod.varp->stamp_xsec = new_xsec;
+		do_gtod.varp->tb_orig_stamp = tb_last_stamp;
+		systemcfg->stamp_xsec = new_xsec;
+		systemcfg->tb_orig_stamp = tb_last_stamp;
+	}
+
+	systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
+	systemcfg->tz_dsttime = sys_tz.tz_dsttime;
+
+	write_sequnlock_irqrestore(&xtime_lock, flags);
+	clock_was_set();
+	return 0;
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+void __init time_init(void)
+{
+	/* This function is only called on the boot processor */
+	unsigned long flags;
+	struct rtc_time tm;
+	struct div_result res;
+	unsigned long scale, shift;
+
+	ppc_md.calibrate_decr();
+
+	/*
+	 * 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;
+
+#ifdef CONFIG_PPC_ISERIES
+	if (!piranha_simulator)
+#endif
+		ppc_md.get_boot_time(&tm);
+
+	write_seqlock_irqsave(&xtime_lock, flags);
+	xtime.tv_sec = mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+			      tm.tm_hour, tm.tm_min, tm.tm_sec);
+	tb_last_stamp = get_tb();
+	do_gtod.varp = &do_gtod.vars[0];
+	do_gtod.var_idx = 0;
+	do_gtod.varp->tb_orig_stamp = tb_last_stamp;
+	do_gtod.varp->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
+	do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
+	do_gtod.varp->tb_to_xs = tb_to_xs;
+	do_gtod.tb_to_us = tb_to_us;
+	systemcfg->tb_orig_stamp = tb_last_stamp;
+	systemcfg->tb_update_count = 0;
+	systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
+	systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
+	systemcfg->tb_to_xs = tb_to_xs;
+
+	time_freq = 0;
+
+	xtime.tv_nsec = 0;
+	last_rtc_update = xtime.tv_sec;
+	set_normalized_timespec(&wall_to_monotonic,
+	                        -xtime.tv_sec, -xtime.tv_nsec);
+	write_sequnlock_irqrestore(&xtime_lock, flags);
+
+	/* Not exact, but the timer interrupt takes care of this */
+	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)
+{
+	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;
+	struct gettimeofday_vars * temp_varp;
+	unsigned temp_idx;
+	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;
+
+	/* There are two copies of tb_to_xs and stamp_xsec so that no lock is needed to access and use these
+	   values in do_gettimeofday.  We alternate the copies and as long as a reasonable time elapses between
+	   changes, there will never be inconsistent values.  ntpd has a minimum of one minute between updates */
+
+	temp_idx = (do_gtod.var_idx == 0);
+	temp_varp = &do_gtod.vars[temp_idx];
+
+	temp_varp->tb_to_xs = new_tb_to_xs;
+	temp_varp->stamp_xsec = new_stamp_xsec;
+	temp_varp->tb_orig_stamp = do_gtod.varp->tb_orig_stamp;
+	mb();
+	do_gtod.varp = temp_varp;
+	do_gtod.var_idx = temp_idx;
+
+	/*
+	 * tb_update_count is used to allow the problem state 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.
+	 */
+	++(systemcfg->tb_update_count);
+	wmb();
+	systemcfg->tb_to_xs = new_tb_to_xs;
+	systemcfg->stamp_xsec = new_stamp_xsec;
+	wmb();
+	++(systemcfg->tb_update_count);
+
+	write_sequnlock_irqrestore( &xtime_lock, flags );
+
+}
+
+
+#define TICK_SIZE tick
+#define FEBRUARY	2
+#define	STARTOFTIME	1970
+#define SECDAY		86400L
+#define SECYR		(SECDAY * 365)
+#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
+};
+
+/*
+ * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
+ */
+void GregorianDay(struct rtc_time * tm)
+{
+	int leapsToDate;
+	int lastYear;
+	int day;
+	int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
+
+	lastYear=tm->tm_year-1;
+
+	/*
+	 * Number of leap corrections to apply up to end of last year
+	 */
+	leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
+
+	/*
+	 * This year is a leap year if it is divisible by 4 except when it is
+	 * divisible by 100 unless it is divisible by 400
+	 *
+	 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
+	 */
+	if((tm->tm_year%4==0) &&
+	   ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
+	   (tm->tm_mon>2))
+	{
+		/*
+		 * We are past Feb. 29 in a leap year
+		 */
+		day=1;
+	}
+	else
+	{
+		day=0;
+	}
+
+	day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
+		   tm->tm_mday;
+
+	tm->tm_wday=day%7;
+}
+
+void to_tm(int tim, struct rtc_time * tm)
+{
+	register int    i;
+	register long   hms, day;
+
+	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
+	 */
+	GregorianDay(tm);
+}
+
+/* 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;
+  }
+
+/*
+ * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
+ * result.
+ */
+
+void div128_by_32( unsigned long dividend_high, unsigned long dividend_low,
+		   unsigned divisor, struct div_result *dr )
+{
+	unsigned long a,b,c,d, w,x,y,z, ra,rb,rc;
+
+	a = dividend_high >> 32;
+	b = dividend_high & 0xffffffff;
+	c = dividend_low >> 32;
+	d = dividend_low & 0xffffffff;
+
+	w = a/divisor;
+	ra = (a - (w * divisor)) << 32;
+
+	x = (ra + b)/divisor;
+	rb = ((ra + b) - (x * divisor)) << 32;
+
+	y = (rb + c)/divisor;
+	rc = ((rb + b) - (y * divisor)) << 32;
+
+	z = (rc + d)/divisor;
+
+	dr->result_high = (w << 32) + x;
+	dr->result_low  = (y << 32) + z;
+
+}
+