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, 1611 insertions, 0 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
new file mode 100644
index 000000000000..ecb3d67c0e14
--- /dev/null
+++ b/kernel/timer.c
@@ -0,0 +1,1611 @@
+/*
+ *  linux/kernel/timer.c
+ *
+ *  Kernel internal timers, kernel timekeeping, basic process system calls
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  1997-01-28  Modified by Finn Arne Gangstad to make timers scale better.
+ *
+ *  1997-09-10  Updated NTP code according to technical memorandum Jan '96
+ *              "A Kernel Model for Precision Timekeeping" by Dave Mills
+ *  1998-12-24  Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
+ *              serialize accesses to xtime/lost_ticks).
+ *                              Copyright (C) 1998  Andrea Arcangeli
+ *  1999-03-10  Improved NTP compatibility by Ulrich Windl
+ *  2002-05-31  Move sys_sysinfo here and make its locking sane, Robert Love
+ *  2000-10-05  Implemented scalable SMP per-CPU timer handling.
+ *                              Copyright (C) 2000, 2001, 2002  Ingo Molnar
+ *              Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/notifier.h>
+#include <linux/thread_info.h>
+#include <linux/time.h>
+#include <linux/jiffies.h>
+#include <linux/posix-timers.h>
+#include <linux/cpu.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/div64.h>
+#include <asm/timex.h>
+#include <asm/io.h>
+
+#ifdef CONFIG_TIME_INTERPOLATION
+static void time_interpolator_update(long delta_nsec);
+#else
+#define time_interpolator_update(x)
+#endif
+
+/*
+ * per-CPU timer vector definitions:
+ */
+
+#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
+#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
+#define TVN_SIZE (1 << TVN_BITS)
+#define TVR_SIZE (1 << TVR_BITS)
+#define TVN_MASK (TVN_SIZE - 1)
+#define TVR_MASK (TVR_SIZE - 1)
+
+typedef struct tvec_s {
+        struct list_head vec[TVN_SIZE];
+} tvec_t;
+
+typedef struct tvec_root_s {
+        struct list_head vec[TVR_SIZE];
+} tvec_root_t;
+
+struct tvec_t_base_s {
+        spinlock_t lock;
+        unsigned long timer_jiffies;
+        struct timer_list *running_timer;
+        tvec_root_t tv1;
+        tvec_t tv2;
+        tvec_t tv3;
+        tvec_t tv4;
+        tvec_t tv5;
+} ____cacheline_aligned_in_smp;
+
+typedef struct tvec_t_base_s tvec_base_t;
+
+static inline void set_running_timer(tvec_base_t *base,
+                                        struct timer_list *timer)
+{
+#ifdef CONFIG_SMP
+        base->running_timer = timer;
+#endif
+}
+
+/* Fake initialization */
+static DEFINE_PER_CPU(tvec_base_t, tvec_bases) = { SPIN_LOCK_UNLOCKED };
+
+static void check_timer_failed(struct timer_list *timer)
+{
+        static int whine_count;
+        if (whine_count < 16) {
+                whine_count++;
+                printk("Uninitialised timer!\n");
+                printk("This is just a warning.  Your computer is OK\n");
+                printk("function=0x%p, data=0x%lx\n",
+                        timer->function, timer->data);
+                dump_stack();
+        }
+        /*
+         * Now fix it up
+         */
+        spin_lock_init(&timer->lock);
+        timer->magic = TIMER_MAGIC;
+}
+
+static inline void check_timer(struct timer_list *timer)
+{
+        if (timer->magic != TIMER_MAGIC)
+                check_timer_failed(timer);
+}
+
+
+static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
+{
+        unsigned long expires = timer->expires;
+        unsigned long idx = expires - base->timer_jiffies;
+        struct list_head *vec;
+
+        if (idx < TVR_SIZE) {
+                int i = expires & TVR_MASK;
+                vec = base->tv1.vec + i;
+        } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
+                int i = (expires >> TVR_BITS) & TVN_MASK;
+                vec = base->tv2.vec + i;
+        } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
+                int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
+                vec = base->tv3.vec + i;
+        } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
+                int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
+                vec = base->tv4.vec + i;
+        } else if ((signed long) idx < 0) {
+                /*
+                 * Can happen if you add a timer with expires == jiffies,
+                 * or you set a timer to go off in the past
+                 */
+                vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
+        } else {
+                int i;
+                /* If the timeout is larger than 0xffffffff on 64-bit
+                 * architectures then we use the maximum timeout:
+                 */
+                if (idx > 0xffffffffUL) {
+                        idx = 0xffffffffUL;
+                        expires = idx + base->timer_jiffies;
+                }
+                i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
+                vec = base->tv5.vec + i;
+        }
+        /*
+         * Timers are FIFO:
+         */
+        list_add_tail(&timer->entry, vec);
+}
+
+int __mod_timer(struct timer_list *timer, unsigned long expires)
+{
+        tvec_base_t *old_base, *new_base;
+        unsigned long flags;
+        int ret = 0;
+
+        BUG_ON(!timer->function);
+
+        check_timer(timer);
+
+        spin_lock_irqsave(&timer->lock, flags);
+        new_base = &__get_cpu_var(tvec_bases);
+repeat:
+        old_base = timer->base;
+
+        /*
+         * Prevent deadlocks via ordering by old_base < new_base.
+         */
+        if (old_base && (new_base != old_base)) {
+                if (old_base < new_base) {
+                        spin_lock(&new_base->lock);
+                        spin_lock(&old_base->lock);
+                } else {
+                        spin_lock(&old_base->lock);
+                        spin_lock(&new_base->lock);
+                }
+                /*
+                 * The timer base might have been cancelled while we were
+                 * trying to take the lock(s):
+                 */
+                if (timer->base != old_base) {
+                        spin_unlock(&new_base->lock);
+                        spin_unlock(&old_base->lock);
+                        goto repeat;
+                }
+        } else {
+                spin_lock(&new_base->lock);
+                if (timer->base != old_base) {
+                        spin_unlock(&new_base->lock);
+                        goto repeat;
+                }
+        }
+
+        /*
+         * Delete the previous timeout (if there was any), and install
+         * the new one:
+         */
+        if (old_base) {
+                list_del(&timer->entry);
+                ret = 1;
+        }
+        timer->expires = expires;
+        internal_add_timer(new_base, timer);
+        timer->base = new_base;
+
+        if (old_base && (new_base != old_base))
+                spin_unlock(&old_base->lock);
+        spin_unlock(&new_base->lock);
+        spin_unlock_irqrestore(&timer->lock, flags);
+
+        return ret;
+}
+
+EXPORT_SYMBOL(__mod_timer);
+
+/***
+ * add_timer_on - start a timer on a particular CPU
+ * @timer: the timer to be added
+ * @cpu: the CPU to start it on
+ *
+ * This is not very scalable on SMP. Double adds are not possible.
+ */
+void add_timer_on(struct timer_list *timer, int cpu)
+{
+        tvec_base_t *base = &per_cpu(tvec_bases, cpu);
+        unsigned long flags;
+  
+        BUG_ON(timer_pending(timer) || !timer->function);
+
+        check_timer(timer);
+
+        spin_lock_irqsave(&base->lock, flags);
+        internal_add_timer(base, timer);
+        timer->base = base;
+        spin_unlock_irqrestore(&base->lock, flags);
+}
+
+
+/***
+ * mod_timer - modify a timer's timeout
+ * @timer: the timer to be modified
+ *
+ * mod_timer is a more efficient way to update the expire field of an
+ * active timer (if the timer is inactive it will be activated)
+ *
+ * mod_timer(timer, expires) is equivalent to:
+ *
+ *     del_timer(timer); timer->expires = expires; add_timer(timer);
+ *
+ * Note that if there are multiple unserialized concurrent users of the
+ * same timer, then mod_timer() is the only safe way to modify the timeout,
+ * since add_timer() cannot modify an already running timer.
+ *
+ * The function returns whether it has modified a pending timer or not.
+ * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
+ * active timer returns 1.)
+ */
+int mod_timer(struct timer_list *timer, unsigned long expires)
+{
+        BUG_ON(!timer->function);
+
+        check_timer(timer);
+
+        /*
+         * This is a common optimization triggered by the
+         * networking code - if the timer is re-modified
+         * to be the same thing then just return:
+         */
+        if (timer->expires == expires && timer_pending(timer))
+                return 1;
+
+        return __mod_timer(timer, expires);
+}
+
+EXPORT_SYMBOL(mod_timer);
+
+/***
+ * del_timer - deactive a timer.
+ * @timer: the timer to be deactivated
+ *
+ * del_timer() deactivates a timer - this works on both active and inactive
+ * timers.
+ *
+ * The function returns whether it has deactivated a pending timer or not.
+ * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
+ * active timer returns 1.)
+ */
+int del_timer(struct timer_list *timer)
+{
+        unsigned long flags;
+        tvec_base_t *base;
+
+        check_timer(timer);
+
+repeat:
+        base = timer->base;
+        if (!base)
+                return 0;
+        spin_lock_irqsave(&base->lock, flags);
+        if (base != timer->base) {
+                spin_unlock_irqrestore(&base->lock, flags);
+                goto repeat;
+        }
+        list_del(&timer->entry);
+        /* Need to make sure that anybody who sees a NULL base also sees the list ops */
+        smp_wmb();
+        timer->base = NULL;
+        spin_unlock_irqrestore(&base->lock, flags);
+
+        return 1;
+}
+
+EXPORT_SYMBOL(del_timer);
+
+#ifdef CONFIG_SMP
+/***
+ * del_timer_sync - deactivate a timer and wait for the handler to finish.
+ * @timer: the timer to be deactivated
+ *
+ * This function only differs from del_timer() on SMP: besides deactivating
+ * the timer it also makes sure the handler has finished executing on other
+ * CPUs.
+ *
+ * Synchronization rules: callers must prevent restarting of the timer,
+ * otherwise this function is meaningless. It must not be called from
+ * interrupt contexts. The caller must not hold locks which would prevent
+ * completion of the timer's handler.  Upon exit the timer is not queued and
+ * the handler is not running on any CPU.
+ *
+ * The function returns whether it has deactivated a pending timer or not.
+ *
+ * del_timer_sync() is slow and complicated because it copes with timer
+ * handlers which re-arm the timer (periodic timers).  If the timer handler
+ * is known to not do this (a single shot timer) then use
+ * del_singleshot_timer_sync() instead.
+ */
+int del_timer_sync(struct timer_list *timer)
+{
+        tvec_base_t *base;
+        int i, ret = 0;
+
+        check_timer(timer);
+
+del_again:
+        ret += del_timer(timer);
+
+        for_each_online_cpu(i) {
+                base = &per_cpu(tvec_bases, i);
+                if (base->running_timer == timer) {
+                        while (base->running_timer == timer) {
+                                cpu_relax();
+                                preempt_check_resched();
+                        }
+                        break;
+                }
+        }
+        smp_rmb();
+        if (timer_pending(timer))
+                goto del_again;
+
+        return ret;
+}
+EXPORT_SYMBOL(del_timer_sync);
+
+/***
+ * del_singleshot_timer_sync - deactivate a non-recursive timer
+ * @timer: the timer to be deactivated
+ *
+ * This function is an optimization of del_timer_sync for the case where the
+ * caller can guarantee the timer does not reschedule itself in its timer
+ * function.
+ *
+ * Synchronization rules: callers must prevent restarting of the timer,
+ * otherwise this function is meaningless. It must not be called from
+ * interrupt contexts. The caller must not hold locks which wold prevent
+ * completion of the timer's handler.  Upon exit the timer is not queued and
+ * the handler is not running on any CPU.
+ *
+ * The function returns whether it has deactivated a pending timer or not.
+ */
+int del_singleshot_timer_sync(struct timer_list *timer)
+{
+        int ret = del_timer(timer);
+
+        if (!ret) {
+                ret = del_timer_sync(timer);
+                BUG_ON(ret);
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL(del_singleshot_timer_sync);
+#endif
+
+static int cascade(tvec_base_t *base, tvec_t *tv, int index)
+{
+        /* cascade all the timers from tv up one level */
+        struct list_head *head, *curr;
+
+        head = tv->vec + index;
+        curr = head->next;
+        /*
+         * We are removing _all_ timers from the list, so we don't  have to
+         * detach them individually, just clear the list afterwards.
+         */
+        while (curr != head) {
+                struct timer_list *tmp;
+
+                tmp = list_entry(curr, struct timer_list, entry);
+                BUG_ON(tmp->base != base);
+                curr = curr->next;
+                internal_add_timer(base, tmp);
+        }
+        INIT_LIST_HEAD(head);
+
+        return index;
+}
+
+/***
+ * __run_timers - run all expired timers (if any) on this CPU.
+ * @base: the timer vector to be processed.
+ *
+ * This function cascades all vectors and executes all expired timer
+ * vectors.
+ */
+#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
+
+static inline void __run_timers(tvec_base_t *base)
+{
+        struct timer_list *timer;
+
+        spin_lock_irq(&base->lock);
+        while (time_after_eq(jiffies, base->timer_jiffies)) {
+                struct list_head work_list = LIST_HEAD_INIT(work_list);
+                struct list_head *head = &work_list;
+                int index = base->timer_jiffies & TVR_MASK;
+ 
+                /*
+                 * Cascade timers:
+                 */
+                if (!index &&
+                        (!cascade(base, &base->tv2, INDEX(0))) &&
+                                (!cascade(base, &base->tv3, INDEX(1))) &&
+                                        !cascade(base, &base->tv4, INDEX(2)))
+                        cascade(base, &base->tv5, INDEX(3));
+                ++base->timer_jiffies; 
+                list_splice_init(base->tv1.vec + index, &work_list);
+repeat:
+                if (!list_empty(head)) {
+                        void (*fn)(unsigned long);
+                        unsigned long data;
+
+                        timer = list_entry(head->next,struct timer_list,entry);
+                        fn = timer->function;
+                        data = timer->data;
+
+                        list_del(&timer->entry);
+                        set_running_timer(base, timer);
+                        smp_wmb();
+                        timer->base = NULL;
+                        spin_unlock_irq(&base->lock);
+                        {
+                                u32 preempt_count = preempt_count();
+                                fn(data);
+                                if (preempt_count != preempt_count()) {
+                                        printk("huh, entered %p with %08x, exited with %08x?\n", fn, preempt_count, preempt_count());
+                                        BUG();
+                                }
+                        }
+                        spin_lock_irq(&base->lock);
+                        goto repeat;
+                }
+        }
+        set_running_timer(base, NULL);
+        spin_unlock_irq(&base->lock);
+}
+
+#ifdef CONFIG_NO_IDLE_HZ
+/*
+ * Find out when the next timer event is due to happen. This
+ * is used on S/390 to stop all activity when a cpus is idle.
+ * This functions needs to be called disabled.
+ */
+unsigned long next_timer_interrupt(void)
+{
+        tvec_base_t *base;
+        struct list_head *list;
+        struct timer_list *nte;
+        unsigned long expires;
+        tvec_t *varray[4];
+        int i, j;
+
+        base = &__get_cpu_var(tvec_bases);
+        spin_lock(&base->lock);
+        expires = base->timer_jiffies + (LONG_MAX >> 1);
+        list = 0;
+
+        /* Look for timer events in tv1. */
+        j = base->timer_jiffies & TVR_MASK;
+        do {
+                list_for_each_entry(nte, base->tv1.vec + j, entry) {
+                        expires = nte->expires;
+                        if (j < (base->timer_jiffies & TVR_MASK))
+                                list = base->tv2.vec + (INDEX(0));
+                        goto found;
+                }
+                j = (j + 1) & TVR_MASK;
+        } while (j != (base->timer_jiffies & TVR_MASK));
+
+        /* Check tv2-tv5. */
+        varray[0] = &base->tv2;
+        varray[1] = &base->tv3;
+        varray[2] = &base->tv4;
+        varray[3] = &base->tv5;
+        for (i = 0; i < 4; i++) {
+                j = INDEX(i);
+                do {
+                        if (list_empty(varray[i]->vec + j)) {
+                                j = (j + 1) & TVN_MASK;
+                                continue;
+                        }
+                        list_for_each_entry(nte, varray[i]->vec + j, entry)
+                                if (time_before(nte->expires, expires))
+                                        expires = nte->expires;
+                        if (j < (INDEX(i)) && i < 3)
+                                list = varray[i + 1]->vec + (INDEX(i + 1));
+                        goto found;
+                } while (j != (INDEX(i)));
+        }
+found:
+        if (list) {
+                /*
+                 * The search wrapped. We need to look at the next list
+                 * from next tv element that would cascade into tv element
+                 * where we found the timer element.
+                 */
+                list_for_each_entry(nte, list, entry) {
+                        if (time_before(nte->expires, expires))
+                                expires = nte->expires;
+                }
+        }
+        spin_unlock(&base->lock);
+        return expires;
+}
+#endif
+
+/******************************************************************/
+
+/*
+ * Timekeeping variables
+ */
+unsigned long tick_usec = TICK_USEC;            /* USER_HZ period (usec) */
+unsigned long tick_nsec = TICK_NSEC;            /* ACTHZ period (nsec) */
+
+/* 
+ * The current time 
+ * wall_to_monotonic is what we need to add to xtime (or xtime corrected 
+ * for sub jiffie times) to get to monotonic time.  Monotonic is pegged
+ * at zero at system boot time, so wall_to_monotonic will be negative,
+ * however, we will ALWAYS keep the tv_nsec part positive so we can use
+ * the usual normalization.
+ */
+struct timespec xtime __attribute__ ((aligned (16)));
+struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
+
+EXPORT_SYMBOL(xtime);
+
+/* Don't completely fail for HZ > 500.  */
+int tickadj = 500/HZ ? : 1;             /* microsecs */
+
+
+/*
+ * phase-lock loop variables
+ */
+/* TIME_ERROR prevents overwriting the CMOS clock */
+int time_state = TIME_OK;               /* clock synchronization status */
+int time_status = STA_UNSYNC;           /* clock status bits            */
+long time_offset;                       /* time adjustment (us)         */
+long time_constant = 2;                 /* pll time constant            */
+long time_tolerance = MAXFREQ;          /* frequency tolerance (ppm)    */
+long time_precision = 1;                /* clock precision (us)         */
+long time_maxerror = NTP_PHASE_LIMIT;   /* maximum error (us)           */
+long time_esterror = NTP_PHASE_LIMIT;   /* estimated error (us)         */
+static long time_phase;                 /* phase offset (scaled us)     */
+long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
+                                        /* frequency offset (scaled ppm)*/
+static long time_adj;                   /* tick adjust (scaled 1 / HZ)  */
+long time_reftime;                      /* time at last adjustment (s)  */
+long time_adjust;
+long time_next_adjust;
+
+/*
+ * this routine handles the overflow of the microsecond field
+ *
+ * The tricky bits of code to handle the accurate clock support
+ * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
+ * They were originally developed for SUN and DEC kernels.
+ * All the kudos should go to Dave for this stuff.
+ *
+ */
+static void second_overflow(void)
+{
+    long ltemp;
+
+    /* Bump the maxerror field */
+    time_maxerror += time_tolerance >> SHIFT_USEC;
+    if ( time_maxerror > NTP_PHASE_LIMIT ) {
+        time_maxerror = NTP_PHASE_LIMIT;
+        time_status |= STA_UNSYNC;
+    }
+
+    /*
+     * Leap second processing. If in leap-insert state at
+     * the end of the day, the system clock is set back one
+     * second; if in leap-delete state, the system clock is
+     * set ahead one second. The microtime() routine or
+     * external clock driver will insure that reported time
+     * is always monotonic. The ugly divides should be
+     * replaced.
+     */
+    switch (time_state) {
+
+    case TIME_OK:
+        if (time_status & STA_INS)
+            time_state = TIME_INS;
+        else if (time_status & STA_DEL)
+            time_state = TIME_DEL;
+        break;
+
+    case TIME_INS:
+        if (xtime.tv_sec % 86400 == 0) {
+            xtime.tv_sec--;
+            wall_to_monotonic.tv_sec++;
+            /* The timer interpolator will make time change gradually instead
+             * of an immediate jump by one second.
+             */
+            time_interpolator_update(-NSEC_PER_SEC);
+            time_state = TIME_OOP;
+            clock_was_set();
+            printk(KERN_NOTICE "Clock: inserting leap second 23:59:60 UTC\n");
+        }
+        break;
+
+    case TIME_DEL:
+        if ((xtime.tv_sec + 1) % 86400 == 0) {
+            xtime.tv_sec++;
+            wall_to_monotonic.tv_sec--;
+            /* Use of time interpolator for a gradual change of time */
+            time_interpolator_update(NSEC_PER_SEC);
+            time_state = TIME_WAIT;
+            clock_was_set();
+            printk(KERN_NOTICE "Clock: deleting leap second 23:59:59 UTC\n");
+        }
+        break;
+
+    case TIME_OOP:
+        time_state = TIME_WAIT;
+        break;
+
+    case TIME_WAIT:
+        if (!(time_status & (STA_INS | STA_DEL)))
+            time_state = TIME_OK;
+    }
+
+    /*
+     * Compute the phase adjustment for the next second. In
+     * PLL mode, the offset is reduced by a fixed factor
+     * times the time constant. In FLL mode the offset is
+     * used directly. In either mode, the maximum phase
+     * adjustment for each second is clamped so as to spread
+     * the adjustment over not more than the number of
+     * seconds between updates.
+     */
+    if (time_offset < 0) {
+        ltemp = -time_offset;
+        if (!(time_status & STA_FLL))
+            ltemp >>= SHIFT_KG + time_constant;
+        if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
+            ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE;
+        time_offset += ltemp;
+        time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
+    } else {
+        ltemp = time_offset;
+        if (!(time_status & STA_FLL))
+            ltemp >>= SHIFT_KG + time_constant;
+        if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
+            ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE;
+        time_offset -= ltemp;
+        time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
+    }
+
+    /*
+     * Compute the frequency estimate and additional phase
+     * adjustment due to frequency error for the next
+     * second. When the PPS signal is engaged, gnaw on the
+     * watchdog counter and update the frequency computed by
+     * the pll and the PPS signal.
+     */
+    pps_valid++;
+    if (pps_valid == PPS_VALID) {       /* PPS signal lost */
+        pps_jitter = MAXTIME;
+        pps_stabil = MAXFREQ;
+        time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
+                         STA_PPSWANDER | STA_PPSERROR);
+    }
+    ltemp = time_freq + pps_freq;
+    if (ltemp < 0)
+        time_adj -= -ltemp >>
+            (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
+    else
+        time_adj += ltemp >>
+            (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
+
+#if HZ == 100
+    /* Compensate for (HZ==100) != (1 << SHIFT_HZ).
+     * Add 25% and 3.125% to get 128.125; => only 0.125% error (p. 14)
+     */
+    if (time_adj < 0)
+        time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
+    else
+        time_adj += (time_adj >> 2) + (time_adj >> 5);
+#endif
+#if HZ == 1000
+    /* Compensate for (HZ==1000) != (1 << SHIFT_HZ).
+     * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
+     */
+    if (time_adj < 0)
+        time_adj -= (-time_adj >> 6) + (-time_adj >> 7);
+    else
+        time_adj += (time_adj >> 6) + (time_adj >> 7);
+#endif
+}
+
+/* in the NTP reference this is called "hardclock()" */
+static void update_wall_time_one_tick(void)
+{
+        long time_adjust_step, delta_nsec;
+
+        if ( (time_adjust_step = time_adjust) != 0 ) {
+            /* We are doing an adjtime thing. 
+             *
+             * Prepare time_adjust_step to be within bounds.
+             * Note that a positive time_adjust means we want the clock
+             * to run faster.
+             *
+             * Limit the amount of the step to be in the range
+             * -tickadj .. +tickadj
+             */
+             if (time_adjust > tickadj)
+                time_adjust_step = tickadj;
+             else if (time_adjust < -tickadj)
+                time_adjust_step = -tickadj;
+
+            /* Reduce by this step the amount of time left  */
+            time_adjust -= time_adjust_step;
+        }
+        delta_nsec = tick_nsec + time_adjust_step * 1000;
+        /*
+         * Advance the phase, once it gets to one microsecond, then
+         * advance the tick more.
+         */
+        time_phase += time_adj;
+        if (time_phase <= -FINENSEC) {
+                long ltemp = -time_phase >> (SHIFT_SCALE - 10);
+                time_phase += ltemp << (SHIFT_SCALE - 10);
+                delta_nsec -= ltemp;
+        }
+        else if (time_phase >= FINENSEC) {
+                long ltemp = time_phase >> (SHIFT_SCALE - 10);
+                time_phase -= ltemp << (SHIFT_SCALE - 10);
+                delta_nsec += ltemp;
+        }
+        xtime.tv_nsec += delta_nsec;
+        time_interpolator_update(delta_nsec);
+
+        /* Changes by adjtime() do not take effect till next tick. */
+        if (time_next_adjust != 0) {
+                time_adjust = time_next_adjust;
+                time_next_adjust = 0;
+        }
+}
+
+/*
+ * Using a loop looks inefficient, but "ticks" is
+ * usually just one (we shouldn't be losing ticks,
+ * we're doing this this way mainly for interrupt
+ * latency reasons, not because we think we'll
+ * have lots of lost timer ticks
+ */
+static void update_wall_time(unsigned long ticks)
+{
+        do {
+                ticks--;
+                update_wall_time_one_tick();
+                if (xtime.tv_nsec >= 1000000000) {
+                        xtime.tv_nsec -= 1000000000;
+                        xtime.tv_sec++;
+                        second_overflow();
+                }
+        } while (ticks);
+}
+
+/*
+ * Called from the timer interrupt handler to charge one tick to the current 
+ * process.  user_tick is 1 if the tick is user time, 0 for system.
+ */
+void update_process_times(int user_tick)
+{
+        struct task_struct *p = current;
+        int cpu = smp_processor_id();
+
+        /* Note: this timer irq context must be accounted for as well. */
+        if (user_tick)
+                account_user_time(p, jiffies_to_cputime(1));
+        else
+                account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
+        run_local_timers();
+        if (rcu_pending(cpu))
+                rcu_check_callbacks(cpu, user_tick);
+        scheduler_tick();
+        run_posix_cpu_timers(p);
+}
+
+/*
+ * Nr of active tasks - counted in fixed-point numbers
+ */
+static unsigned long count_active_tasks(void)
+{
+        return (nr_running() + nr_uninterruptible()) * FIXED_1;
+}
+
+/*
+ * Hmm.. Changed this, as the GNU make sources (load.c) seems to
+ * imply that avenrun[] is the standard name for this kind of thing.
+ * Nothing else seems to be standardized: the fractional size etc
+ * all seem to differ on different machines.
+ *
+ * Requires xtime_lock to access.
+ */
+unsigned long avenrun[3];
+
+EXPORT_SYMBOL(avenrun);
+
+/*
+ * calc_load - given tick count, update the avenrun load estimates.
+ * This is called while holding a write_lock on xtime_lock.
+ */
+static inline void calc_load(unsigned long ticks)
+{
+        unsigned long active_tasks; /* fixed-point */
+        static int count = LOAD_FREQ;
+
+        count -= ticks;
+        if (count < 0) {
+                count += LOAD_FREQ;
+                active_tasks = count_active_tasks();
+                CALC_LOAD(avenrun[0], EXP_1, active_tasks);
+                CALC_LOAD(avenrun[1], EXP_5, active_tasks);
+                CALC_LOAD(avenrun[2], EXP_15, active_tasks);
+        }
+}
+
+/* jiffies at the most recent update of wall time */
+unsigned long wall_jiffies = INITIAL_JIFFIES;
+
+/*
+ * This read-write spinlock protects us from races in SMP while
+ * playing with xtime and avenrun.
+ */
+#ifndef ARCH_HAVE_XTIME_LOCK
+seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED;
+
+EXPORT_SYMBOL(xtime_lock);
+#endif
+
+/*
+ * This function runs timers and the timer-tq in bottom half context.
+ */
+static void run_timer_softirq(struct softirq_action *h)
+{
+        tvec_base_t *base = &__get_cpu_var(tvec_bases);
+
+        if (time_after_eq(jiffies, base->timer_jiffies))
+                __run_timers(base);
+}
+
+/*
+ * Called by the local, per-CPU timer interrupt on SMP.
+ */
+void run_local_timers(void)
+{
+        raise_softirq(TIMER_SOFTIRQ);
+}
+
+/*
+ * Called by the timer interrupt. xtime_lock must already be taken
+ * by the timer IRQ!
+ */
+static inline void update_times(void)
+{
+        unsigned long ticks;
+
+        ticks = jiffies - wall_jiffies;
+        if (ticks) {
+                wall_jiffies += ticks;
+                update_wall_time(ticks);
+        }
+        calc_load(ticks);
+}
+  
+/*
+ * The 64-bit jiffies value is not atomic - you MUST NOT read it
+ * without sampling the sequence number in xtime_lock.
+ * jiffies is defined in the linker script...
+ */
+
+void do_timer(struct pt_regs *regs)
+{
+        jiffies_64++;
+        update_times();
+}
+
+#ifdef __ARCH_WANT_SYS_ALARM
+
+/*
+ * For backwards compatibility?  This can be done in libc so Alpha
+ * and all newer ports shouldn't need it.
+ */
+asmlinkage unsigned long sys_alarm(unsigned int seconds)
+{
+        struct itimerval it_new, it_old;
+        unsigned int oldalarm;
+
+        it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
+        it_new.it_value.tv_sec = seconds;
+        it_new.it_value.tv_usec = 0;
+        do_setitimer(ITIMER_REAL, &it_new, &it_old);
+        oldalarm = it_old.it_value.tv_sec;
+        /* ehhh.. We can't return 0 if we have an alarm pending.. */
+        /* And we'd better return too much than too little anyway */
+        if ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000)
+                oldalarm++;
+        return oldalarm;
+}
+
+#endif
+
+#ifndef __alpha__
+
+/*
+ * The Alpha uses getxpid, getxuid, and getxgid instead.  Maybe this
+ * should be moved into arch/i386 instead?
+ */
+
+/**
+ * sys_getpid - return the thread group id of the current process
+ *
+ * Note, despite the name, this returns the tgid not the pid.  The tgid and
+ * the pid are identical unless CLONE_THREAD was specified on clone() in
+ * which case the tgid is the same in all threads of the same group.
+ *
+ * This is SMP safe as current->tgid does not change.
+ */
+asmlinkage long sys_getpid(void)
+{
+        return current->tgid;
+}
+
+/*
+ * Accessing ->group_leader->real_parent is not SMP-safe, it could
+ * change from under us. However, rather than getting any lock
+ * we can use an optimistic algorithm: get the parent
+ * pid, and go back and check that the parent is still
+ * the same. If it has changed (which is extremely unlikely
+ * indeed), we just try again..
+ *
+ * NOTE! This depends on the fact that even if we _do_
+ * get an old value of "parent", we can happily dereference
+ * the pointer (it was and remains a dereferencable kernel pointer
+ * no matter what): we just can't necessarily trust the result
+ * until we know that the parent pointer is valid.
+ *
+ * NOTE2: ->group_leader never changes from under us.
+ */
+asmlinkage long sys_getppid(void)
+{
+        int pid;
+        struct task_struct *me = current;
+        struct task_struct *parent;
+
+        parent = me->group_leader->real_parent;
+        for (;;) {
+                pid = parent->tgid;
+#ifdef CONFIG_SMP
+{
+                struct task_struct *old = parent;
+
+                /*
+                 * Make sure we read the pid before re-reading the
+                 * parent pointer:
+                 */
+                rmb();
+                parent = me->group_leader->real_parent;
+                if (old != parent)
+                        continue;
+}
+#endif
+                break;
+        }
+        return pid;
+}
+
+asmlinkage long sys_getuid(void)
+{
+        /* Only we change this so SMP safe */
+        return current->uid;
+}
+
+asmlinkage long sys_geteuid(void)
+{
+        /* Only we change this so SMP safe */
+        return current->euid;
+}
+
+asmlinkage long sys_getgid(void)
+{
+        /* Only we change this so SMP safe */
+        return current->gid;
+}
+
+asmlinkage long sys_getegid(void)
+{
+        /* Only we change this so SMP safe */
+        return  current->egid;
+}
+
+#endif
+
+static void process_timeout(unsigned long __data)
+{
+        wake_up_process((task_t *)__data);
+}
+
+/**
+ * schedule_timeout - sleep until timeout
+ * @timeout: timeout value in jiffies
+ *
+ * Make the current task sleep until @timeout jiffies have
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
+ * pass before the routine returns. The routine will return 0
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task. In this case the remaining time
+ * in jiffies will be returned, or 0 if the timer expired in time
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
+ * the CPU away without a bound on the timeout. In this case the return
+ * value will be %MAX_SCHEDULE_TIMEOUT.
+ *
+ * In all cases the return value is guaranteed to be non-negative.
+ */
+fastcall signed long __sched schedule_timeout(signed long timeout)
+{
+        struct timer_list timer;
+        unsigned long expire;
+
+        switch (timeout)
+        {
+        case MAX_SCHEDULE_TIMEOUT:
+                /*
+                 * These two special cases are useful to be comfortable
+                 * in the caller. Nothing more. We could take
+                 * MAX_SCHEDULE_TIMEOUT from one of the negative value
+                 * but I' d like to return a valid offset (>=0) to allow
+                 * the caller to do everything it want with the retval.
+                 */
+                schedule();
+                goto out;
+        default:
+                /*
+                 * Another bit of PARANOID. Note that the retval will be
+                 * 0 since no piece of kernel is supposed to do a check
+                 * for a negative retval of schedule_timeout() (since it
+                 * should never happens anyway). You just have the printk()
+                 * that will tell you if something is gone wrong and where.
+                 */
+                if (timeout < 0)
+                {
+                        printk(KERN_ERR "schedule_timeout: wrong timeout "
+                               "value %lx from %p\n", timeout,
+                               __builtin_return_address(0));
+                        current->state = TASK_RUNNING;
+                        goto out;
+                }
+        }
+
+        expire = timeout + jiffies;
+
+        init_timer(&timer);
+        timer.expires = expire;
+        timer.data = (unsigned long) current;
+        timer.function = process_timeout;
+
+        add_timer(&timer);
+        schedule();
+        del_singleshot_timer_sync(&timer);
+
+        timeout = expire - jiffies;
+
+ out:
+        return timeout < 0 ? 0 : timeout;
+}
+
+EXPORT_SYMBOL(schedule_timeout);
+
+/* Thread ID - the internal kernel "pid" */
+asmlinkage long sys_gettid(void)
+{
+        return current->pid;
+}
+
+static long __sched nanosleep_restart(struct restart_block *restart)
+{
+        unsigned long expire = restart->arg0, now = jiffies;
+        struct timespec __user *rmtp = (struct timespec __user *) restart->arg1;
+        long ret;
+
+        /* Did it expire while we handled signals? */
+        if (!time_after(expire, now))
+                return 0;
+
+        current->state = TASK_INTERRUPTIBLE;
+        expire = schedule_timeout(expire - now);
+
+        ret = 0;
+        if (expire) {
+                struct timespec t;
+                jiffies_to_timespec(expire, &t);
+
+                ret = -ERESTART_RESTARTBLOCK;
+                if (rmtp && copy_to_user(rmtp, &t, sizeof(t)))
+                        ret = -EFAULT;
+                /* The 'restart' block is already filled in */
+        }
+        return ret;
+}
+
+asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
+{
+        struct timespec t;
+        unsigned long expire;
+        long ret;
+
+        if (copy_from_user(&t, rqtp, sizeof(t)))
+                return -EFAULT;
+
+        if ((t.tv_nsec >= 1000000000L) || (t.tv_nsec < 0) || (t.tv_sec < 0))
+                return -EINVAL;
+
+        expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
+        current->state = TASK_INTERRUPTIBLE;
+        expire = schedule_timeout(expire);
+
+        ret = 0;
+        if (expire) {
+                struct restart_block *restart;
+                jiffies_to_timespec(expire, &t);
+                if (rmtp && copy_to_user(rmtp, &t, sizeof(t)))
+                        return -EFAULT;
+
+                restart = &current_thread_info()->restart_block;
+                restart->fn = nanosleep_restart;
+                restart->arg0 = jiffies + expire;
+                restart->arg1 = (unsigned long) rmtp;
+                ret = -ERESTART_RESTARTBLOCK;
+        }
+        return ret;
+}
+
+/*
+ * sys_sysinfo - fill in sysinfo struct
+ */ 
+asmlinkage long sys_sysinfo(struct sysinfo __user *info)
+{
+        struct sysinfo val;
+        unsigned long mem_total, sav_total;
+        unsigned int mem_unit, bitcount;
+        unsigned long seq;
+
+        memset((char *)&val, 0, sizeof(struct sysinfo));
+
+        do {
+                struct timespec tp;
+                seq = read_seqbegin(&xtime_lock);
+
+                /*
+                 * This is annoying.  The below is the same thing
+                 * posix_get_clock_monotonic() does, but it wants to
+                 * take the lock which we want to cover the loads stuff
+                 * too.
+                 */
+
+                getnstimeofday(&tp);
+                tp.tv_sec += wall_to_monotonic.tv_sec;
+                tp.tv_nsec += wall_to_monotonic.tv_nsec;
+                if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
+                        tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
+                        tp.tv_sec++;
+                }
+                val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
+
+                val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
+                val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
+                val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
+
+                val.procs = nr_threads;
+        } while (read_seqretry(&xtime_lock, seq));
+
+        si_meminfo(&val);
+        si_swapinfo(&val);
+
+        /*
+         * If the sum of all the available memory (i.e. ram + swap)
+         * is less than can be stored in a 32 bit unsigned long then
+         * we can be binary compatible with 2.2.x kernels.  If not,
+         * well, in that case 2.2.x was broken anyways...
+         *
+         *  -Erik Andersen <andersee@debian.org>
+         */
+
+        mem_total = val.totalram + val.totalswap;
+        if (mem_total < val.totalram || mem_total < val.totalswap)
+                goto out;
+        bitcount = 0;
+        mem_unit = val.mem_unit;
+        while (mem_unit > 1) {
+                bitcount++;
+                mem_unit >>= 1;
+                sav_total = mem_total;
+                mem_total <<= 1;
+                if (mem_total < sav_total)
+                        goto out;
+        }
+
+        /*
+         * If mem_total did not overflow, multiply all memory values by
+         * val.mem_unit and set it to 1.  This leaves things compatible
+         * with 2.2.x, and also retains compatibility with earlier 2.4.x
+         * kernels...
+         */
+
+        val.mem_unit = 1;
+        val.totalram <<= bitcount;
+        val.freeram <<= bitcount;
+        val.sharedram <<= bitcount;
+        val.bufferram <<= bitcount;
+        val.totalswap <<= bitcount;
+        val.freeswap <<= bitcount;
+        val.totalhigh <<= bitcount;
+        val.freehigh <<= bitcount;
+
+ out:
+        if (copy_to_user(info, &val, sizeof(struct sysinfo)))
+                return -EFAULT;
+
+        return 0;
+}
+
+static void __devinit init_timers_cpu(int cpu)
+{
+        int j;
+        tvec_base_t *base;
+       
+        base = &per_cpu(tvec_bases, cpu);
+        spin_lock_init(&base->lock);
+        for (j = 0; j < TVN_SIZE; j++) {
+                INIT_LIST_HEAD(base->tv5.vec + j);
+                INIT_LIST_HEAD(base->tv4.vec + j);
+                INIT_LIST_HEAD(base->tv3.vec + j);
+                INIT_LIST_HEAD(base->tv2.vec + j);
+        }
+        for (j = 0; j < TVR_SIZE; j++)
+                INIT_LIST_HEAD(base->tv1.vec + j);
+
+        base->timer_jiffies = jiffies;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
+{
+        struct timer_list *timer;
+
+        while (!list_empty(head)) {
+                timer = list_entry(head->next, struct timer_list, entry);
+                /* We're locking backwards from __mod_timer order here,
+                   beware deadlock. */
+                if (!spin_trylock(&timer->lock))
+                        return 0;
+                list_del(&timer->entry);
+                internal_add_timer(new_base, timer);
+                timer->base = new_base;
+                spin_unlock(&timer->lock);
+        }
+        return 1;
+}
+
+static void __devinit migrate_timers(int cpu)
+{
+        tvec_base_t *old_base;
+        tvec_base_t *new_base;
+        int i;
+
+        BUG_ON(cpu_online(cpu));
+        old_base = &per_cpu(tvec_bases, cpu);
+        new_base = &get_cpu_var(tvec_bases);
+
+        local_irq_disable();
+again:
+        /* Prevent deadlocks via ordering by old_base < new_base. */
+        if (old_base < new_base) {
+                spin_lock(&new_base->lock);
+                spin_lock(&old_base->lock);
+        } else {
+                spin_lock(&old_base->lock);
+                spin_lock(&new_base->lock);
+        }
+
+        if (old_base->running_timer)
+                BUG();
+        for (i = 0; i < TVR_SIZE; i++)
+                if (!migrate_timer_list(new_base, old_base->tv1.vec + i))
+                        goto unlock_again;
+        for (i = 0; i < TVN_SIZE; i++)
+                if (!migrate_timer_list(new_base, old_base->tv2.vec + i)
+                    || !migrate_timer_list(new_base, old_base->tv3.vec + i)
+                    || !migrate_timer_list(new_base, old_base->tv4.vec + i)
+                    || !migrate_timer_list(new_base, old_base->tv5.vec + i))
+                        goto unlock_again;
+        spin_unlock(&old_base->lock);
+        spin_unlock(&new_base->lock);
+        local_irq_enable();
+        put_cpu_var(tvec_bases);
+        return;
+
+unlock_again:
+        /* Avoid deadlock with __mod_timer, by backing off. */
+        spin_unlock(&old_base->lock);
+        spin_unlock(&new_base->lock);
+        cpu_relax();
+        goto again;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static int __devinit timer_cpu_notify(struct notifier_block *self, 
+                                unsigned long action, void *hcpu)
+{
+        long cpu = (long)hcpu;
+        switch(action) {
+        case CPU_UP_PREPARE:
+                init_timers_cpu(cpu);
+                break;
+#ifdef CONFIG_HOTPLUG_CPU
+        case CPU_DEAD:
+                migrate_timers(cpu);
+                break;
+#endif
+        default:
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __devinitdata timers_nb = {
+        .notifier_call  = timer_cpu_notify,
+};
+
+
+void __init init_timers(void)
+{
+        timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
+                                (void *)(long)smp_processor_id());
+        register_cpu_notifier(&timers_nb);
+        open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
+}
+
+#ifdef CONFIG_TIME_INTERPOLATION
+
+struct time_interpolator *time_interpolator;
+static struct time_interpolator *time_interpolator_list;
+static DEFINE_SPINLOCK(time_interpolator_lock);
+
+static inline u64 time_interpolator_get_cycles(unsigned int src)
+{
+        unsigned long (*x)(void);
+
+        switch (src)
+        {
+                case TIME_SOURCE_FUNCTION:
+                        x = time_interpolator->addr;
+                        return x();
+
+                case TIME_SOURCE_MMIO64 :
+                        return readq((void __iomem *) time_interpolator->addr);
+
+                case TIME_SOURCE_MMIO32 :
+                        return readl((void __iomem *) time_interpolator->addr);
+
+                default: return get_cycles();
+        }
+}
+
+static inline u64 time_interpolator_get_counter(void)
+{
+        unsigned int src = time_interpolator->source;
+
+        if (time_interpolator->jitter)
+        {
+                u64 lcycle;
+                u64 now;
+
+                do {
+                        lcycle = time_interpolator->last_cycle;
+                        now = time_interpolator_get_cycles(src);
+                        if (lcycle && time_after(lcycle, now))
+                                return lcycle;
+                        /* Keep track of the last timer value returned. The use of cmpxchg here
+                         * will cause contention in an SMP environment.
+                         */
+                } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
+                return now;
+        }
+        else
+                return time_interpolator_get_cycles(src);
+}
+
+void time_interpolator_reset(void)
+{
+        time_interpolator->offset = 0;
+        time_interpolator->last_counter = time_interpolator_get_counter();
+}
+
+#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
+
+unsigned long time_interpolator_get_offset(void)
+{
+        /* If we do not have a time interpolator set up then just return zero */
+        if (!time_interpolator)
+                return 0;
+
+        return time_interpolator->offset +
+                GET_TI_NSECS(time_interpolator_get_counter(), time_interpolator);
+}
+
+#define INTERPOLATOR_ADJUST 65536
+#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
+
+static void time_interpolator_update(long delta_nsec)
+{
+        u64 counter;
+        unsigned long offset;
+
+        /* If there is no time interpolator set up then do nothing */
+        if (!time_interpolator)
+                return;
+
+        /* The interpolator compensates for late ticks by accumulating
+         * the late time in time_interpolator->offset. A tick earlier than
+         * expected will lead to a reset of the offset and a corresponding
+         * jump of the clock forward. Again this only works if the
+         * interpolator clock is running slightly slower than the regular clock
+         * and the tuning logic insures that.
+         */
+
+        counter = time_interpolator_get_counter();
+        offset = time_interpolator->offset + GET_TI_NSECS(counter, time_interpolator);
+
+        if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
+                time_interpolator->offset = offset - delta_nsec;
+        else {
+                time_interpolator->skips++;
+                time_interpolator->ns_skipped += delta_nsec - offset;
+                time_interpolator->offset = 0;
+        }
+        time_interpolator->last_counter = counter;
+
+        /* Tuning logic for time interpolator invoked every minute or so.
+         * Decrease interpolator clock speed if no skips occurred and an offset is carried.
+         * Increase interpolator clock speed if we skip too much time.
+         */
+        if (jiffies % INTERPOLATOR_ADJUST == 0)
+        {
+                if (time_interpolator->skips == 0 && time_interpolator->offset > TICK_NSEC)
+                        time_interpolator->nsec_per_cyc--;
+                if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
+                        time_interpolator->nsec_per_cyc++;
+                time_interpolator->skips = 0;
+                time_interpolator->ns_skipped = 0;
+        }
+}
+
+static inline int
+is_better_time_interpolator(struct time_interpolator *new)
+{
+        if (!time_interpolator)
+                return 1;
+        return new->frequency > 2*time_interpolator->frequency ||
+            (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
+}
+
+void
+register_time_interpolator(struct time_interpolator *ti)
+{
+        unsigned long flags;
+
+        /* Sanity check */
+        if (ti->frequency == 0 || ti->mask == 0)
+                BUG();
+
+        ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
+        spin_lock(&time_interpolator_lock);
+        write_seqlock_irqsave(&xtime_lock, flags);
+        if (is_better_time_interpolator(ti)) {
+                time_interpolator = ti;
+                time_interpolator_reset();
+        }
+        write_sequnlock_irqrestore(&xtime_lock, flags);
+
+        ti->next = time_interpolator_list;
+        time_interpolator_list = ti;
+        spin_unlock(&time_interpolator_lock);
+}
+
+void
+unregister_time_interpolator(struct time_interpolator *ti)
+{
+        struct time_interpolator *curr, **prev;
+        unsigned long flags;
+
+        spin_lock(&time_interpolator_lock);
+        prev = &time_interpolator_list;
+        for (curr = *prev; curr; curr = curr->next) {
+                if (curr == ti) {
+                        *prev = curr->next;
+                        break;
+                }
+                prev = &curr->next;
+        }
+
+        write_seqlock_irqsave(&xtime_lock, flags);
+        if (ti == time_interpolator) {
+                /* we lost the best time-interpolator: */
+                time_interpolator = NULL;
+                /* find the next-best interpolator */
+                for (curr = time_interpolator_list; curr; curr = curr->next)
+                        if (is_better_time_interpolator(curr))
+                                time_interpolator = curr;
+                time_interpolator_reset();
+        }
+        write_sequnlock_irqrestore(&xtime_lock, flags);
+        spin_unlock(&time_interpolator_lock);
+}
+#endif /* CONFIG_TIME_INTERPOLATION */
+
+/**
+ * msleep - sleep safely even with waitqueue interruptions
+ * @msecs: Time in milliseconds to sleep for
+ */
+void msleep(unsigned int msecs)
+{
+        unsigned long timeout = msecs_to_jiffies(msecs) + 1;
+
+        while (timeout) {
+                set_current_state(TASK_UNINTERRUPTIBLE);
+                timeout = schedule_timeout(timeout);
+        }
+}
+
+EXPORT_SYMBOL(msleep);
+
+/**
+ * msleep_interruptible - sleep waiting for waitqueue interruptions
+ * @msecs: Time in milliseconds to sleep for
+ */
+unsigned long msleep_interruptible(unsigned int msecs)
+{
+        unsigned long timeout = msecs_to_jiffies(msecs) + 1;
+
+        while (timeout && !signal_pending(current)) {
+                set_current_state(TASK_INTERRUPTIBLE);
+                timeout = schedule_timeout(timeout);
+        }
+        return jiffies_to_msecs(timeout);
+}
+
+EXPORT_SYMBOL(msleep_interruptible);