6 files changed, 148 insertions, 120 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index bfe8f72..6781765 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -217,7 +217,7 @@ static void hpet_reserve_platform_timers(unsigned int id) { }
 /*
  * Common hpet info
  */
-static unsigned long hpet_period;
+static unsigned long hpet_freq;
 
 static void hpet_legacy_set_mode(enum clock_event_mode mode,
 			  struct clock_event_device *evt);
@@ -232,7 +232,6 @@ static struct clock_event_device hpet_clockevent = {
 	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.set_mode	= hpet_legacy_set_mode,
 	.set_next_event = hpet_legacy_next_event,
-	.shift		= 32,
 	.irq		= 0,
 	.rating		= 50,
 };
@@ -290,28 +289,12 @@ static void hpet_legacy_clockevent_register(void)
 	hpet_enable_legacy_int();
 
 	/*
-	 * The mult factor is defined as (include/linux/clockchips.h)
-	 *  mult/2^shift = cyc/ns (in contrast to ns/cyc in clocksource.h)
-	 * hpet_period is in units of femtoseconds (per cycle), so
-	 *  mult/2^shift = cyc/ns = 10^6/hpet_period
-	 *  mult = (10^6 * 2^shift)/hpet_period
-	 *  mult = (FSEC_PER_NSEC << hpet_clockevent.shift)/hpet_period
-	 */
-	hpet_clockevent.mult = div_sc((unsigned long) FSEC_PER_NSEC,
-				      hpet_period, hpet_clockevent.shift);
-	/* Calculate the min / max delta */
-	hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
-							   &hpet_clockevent);
-	/* Setup minimum reprogramming delta. */
-	hpet_clockevent.min_delta_ns = clockevent_delta2ns(HPET_MIN_PROG_DELTA,
-							   &hpet_clockevent);
-
-	/*
 	 * Start hpet with the boot cpu mask and make it
 	 * global after the IO_APIC has been initialized.
 	 */
 	hpet_clockevent.cpumask = cpumask_of(smp_processor_id());
-	clockevents_register_device(&hpet_clockevent);
+	clockevents_config_and_register(&hpet_clockevent, hpet_freq,
+					HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
 	global_clock_event = &hpet_clockevent;
 	printk(KERN_DEBUG "hpet clockevent registered\n");
 }
@@ -549,7 +532,6 @@ static int hpet_setup_irq(struct hpet_dev *dev)
 static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
 {
 	struct clock_event_device *evt = &hdev->evt;
-	uint64_t hpet_freq;
 
 	WARN_ON(cpu != smp_processor_id());
 	if (!(hdev->flags & HPET_DEV_VALID))
@@ -571,24 +553,10 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
 
 	evt->set_mode = hpet_msi_set_mode;
 	evt->set_next_event = hpet_msi_next_event;
-	evt->shift = 32;
-
-	/*
-	 * The period is a femto seconds value. We need to calculate the
-	 * scaled math multiplication factor for nanosecond to hpet tick
-	 * conversion.
-	 */
-	hpet_freq = FSEC_PER_SEC;
-	do_div(hpet_freq, hpet_period);
-	evt->mult = div_sc((unsigned long) hpet_freq,
-				      NSEC_PER_SEC, evt->shift);
-	/* Calculate the max delta */
-	evt->max_delta_ns = clockevent_delta2ns(0x7FFFFFFF, evt);
-	/* 5 usec minimum reprogramming delta. */
-	evt->min_delta_ns = 5000;
-
 	evt->cpumask = cpumask_of(hdev->cpu);
-	clockevents_register_device(evt);
+
+	clockevents_config_and_register(evt, hpet_freq, HPET_MIN_PROG_DELTA,
+					0x7FFFFFFF);
 }
 
 #ifdef CONFIG_HPET
@@ -792,7 +760,6 @@ static struct clocksource clocksource_hpet = {
 static int hpet_clocksource_register(void)
 {
 	u64 start, now;
-	u64 hpet_freq;
 	cycle_t t1;
 
 	/* Start the counter */
@@ -819,24 +786,7 @@ static int hpet_clocksource_register(void)
 		return -ENODEV;
 	}
 
-	/*
-	 * The definition of mult is (include/linux/clocksource.h)
-	 * mult/2^shift = ns/cyc and hpet_period is in units of fsec/cyc
-	 * so we first need to convert hpet_period to ns/cyc units:
-	 *  mult/2^shift = ns/cyc = hpet_period/10^6
-	 *  mult = (hpet_period * 2^shift)/10^6
-	 *  mult = (hpet_period << shift)/FSEC_PER_NSEC
-	 */
-
-	/* Need to convert hpet_period (fsec/cyc) to cyc/sec:
-	 *
-	 * cyc/sec = FSEC_PER_SEC/hpet_period(fsec/cyc)
-	 * cyc/sec = (FSEC_PER_NSEC * NSEC_PER_SEC)/hpet_period
-	 */
-	hpet_freq = FSEC_PER_SEC;
-	do_div(hpet_freq, hpet_period);
 	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
-
 	return 0;
 }
 
@@ -845,7 +795,9 @@ static int hpet_clocksource_register(void)
  */
 int __init hpet_enable(void)
 {
+	unsigned long hpet_period;
 	unsigned int id;
+	u64 freq;
 	int i;
 
 	if (!is_hpet_capable())
@@ -884,6 +836,14 @@ int __init hpet_enable(void)
 		goto out_nohpet;
 
 	/*
+	 * The period is a femto seconds value. Convert it to a
+	 * frequency.
+	 */
+	freq = FSEC_PER_SEC;
+	do_div(freq, hpet_period);
+	hpet_freq = freq;
+
+	/*
 	 * Read the HPET ID register to retrieve the IRQ routing
 	 * information and the number of channels
 	 */
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c
index 577e90c..fb66dc9 100644
--- a/arch/x86/kernel/i8253.c
+++ b/arch/x86/kernel/i8253.c
@@ -93,7 +93,6 @@ static struct clock_event_device pit_ce = {
 	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.set_mode	= init_pit_timer,
 	.set_next_event = pit_next_event,
-	.shift		= 32,
 	.irq		= 0,
 };
 
@@ -108,11 +107,8 @@ void __init setup_pit_timer(void)
 	 * IO_APIC has been initialized.
 	 */
 	pit_ce.cpumask = cpumask_of(smp_processor_id());
-	pit_ce.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, pit_ce.shift);
-	pit_ce.max_delta_ns = clockevent_delta2ns(0x7FFF, &pit_ce);
-	pit_ce.min_delta_ns = clockevent_delta2ns(0xF, &pit_ce);
 
-	clockevents_register_device(&pit_ce);
+	clockevents_config_and_register(&pit_ce, CLOCK_TICK_RATE, 0xF, 0x7FFF);
 	global_clock_event = &pit_ce;
 }
 
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index fc53492..d6733e2 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -56,46 +56,52 @@ enum clock_event_nofitiers {
 
 /**
  * struct clock_event_device - clock event device descriptor
- * @name:		ptr to clock event name
- * @features:		features
+ * @event_handler:	Assigned by the framework to be called by the low
+ *			level handler of the event source
+ * @set_next_event:	set next event function
+ * @next_event:		local storage for the next event in oneshot mode
  * @max_delta_ns:	maximum delta value in ns
  * @min_delta_ns:	minimum delta value in ns
  * @mult:		nanosecond to cycles multiplier
  * @shift:		nanoseconds to cycles divisor (power of two)
+ * @mode:		operating mode assigned by the management code
+ * @features:		features
+ * @retries:		number of forced programming retries
+ * @set_mode:		set mode function
+ * @broadcast:		function to broadcast events
+ * @min_delta_ticks:	minimum delta value in ticks stored for reconfiguration
+ * @max_delta_ticks:	maximum delta value in ticks stored for reconfiguration
+ * @name:		ptr to clock event name
  * @rating:		variable to rate clock event devices
  * @irq:		IRQ number (only for non CPU local devices)
  * @cpumask:		cpumask to indicate for which CPUs this device works
- * @set_next_event:	set next event function
- * @set_mode:		set mode function
- * @event_handler:	Assigned by the framework to be called by the low
- *			level handler of the event source
- * @broadcast:		function to broadcast events
  * @list:		list head for the management code
- * @mode:		operating mode assigned by the management code
- * @next_event:		local storage for the next event in oneshot mode
- * @retries:		number of forced programming retries
  */
 struct clock_event_device {
-	const char		*name;
-	unsigned int		features;
+	void			(*event_handler)(struct clock_event_device *);
+	int			(*set_next_event)(unsigned long evt,
+						  struct clock_event_device *);
+	ktime_t			next_event;
 	u64			max_delta_ns;
 	u64			min_delta_ns;
 	u32			mult;
 	u32			shift;
+	enum clock_event_mode	mode;
+	unsigned int		features;
+	unsigned long		retries;
+
+	void			(*broadcast)(const struct cpumask *mask);
+	void			(*set_mode)(enum clock_event_mode mode,
+					    struct clock_event_device *);
+	unsigned long		min_delta_ticks;
+	unsigned long		max_delta_ticks;
+
+	const char		*name;
 	int			rating;
 	int			irq;
 	const struct cpumask	*cpumask;
-	int			(*set_next_event)(unsigned long evt,
-						  struct clock_event_device *);
-	void			(*set_mode)(enum clock_event_mode mode,
-					    struct clock_event_device *);
-	void			(*event_handler)(struct clock_event_device *);
-	void			(*broadcast)(const struct cpumask *mask);
 	struct list_head	list;
-	enum clock_event_mode	mode;
-	ktime_t			next_event;
-	unsigned long		retries;
-};
+} ____cacheline_aligned;
 
 /*
  * Calculate a multiplication factor for scaled math, which is used to convert
@@ -122,6 +128,12 @@ extern u64 clockevent_delta2ns(unsigned long latch,
 			       struct clock_event_device *evt);
 extern void clockevents_register_device(struct clock_event_device *dev);
 
+extern void clockevents_config_and_register(struct clock_event_device *dev,
+					    u32 freq, unsigned long min_delta,
+					    unsigned long max_delta);
+
+extern int clockevents_update_freq(struct clock_event_device *ce, u32 freq);
+
 extern void clockevents_exchange_device(struct clock_event_device *old,
 					struct clock_event_device *new);
 extern void clockevents_set_mode(struct clock_event_device *dev,
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 0fb0b7e..c918fbd 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -159,42 +159,38 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
  */
 struct clocksource {
 	/*
-	 * First part of structure is read mostly
+	 * Hotpath data, fits in a single cache line when the
+	 * clocksource itself is cacheline aligned.
 	 */
-	const char *name;
-	struct list_head list;
-	int rating;
 	cycle_t (*read)(struct clocksource *cs);
-	int (*enable)(struct clocksource *cs);
-	void (*disable)(struct clocksource *cs);
+	cycle_t cycle_last;
 	cycle_t mask;
 	u32 mult;
 	u32 shift;
 	u64 max_idle_ns;
-	unsigned long flags;
-	cycle_t (*vread)(void);
-	void (*suspend)(struct clocksource *cs);
-	void (*resume)(struct clocksource *cs);
+
 #ifdef CONFIG_IA64
 	void *fsys_mmio;        /* used by fsyscall asm code */
 #define CLKSRC_FSYS_MMIO_SET(mmio, addr)      ((mmio) = (addr))
 #else
 #define CLKSRC_FSYS_MMIO_SET(mmio, addr)      do { } while (0)
 #endif
-
-	/*
-	 * Second part is written at each timer interrupt
-	 * Keep it in a different cache line to dirty no
-	 * more than one cache line.
-	 */
-	cycle_t cycle_last ____cacheline_aligned_in_smp;
+	const char *name;
+	struct list_head list;
+	int rating;
+	cycle_t (*vread)(void);
+	int (*enable)(struct clocksource *cs);
+	void (*disable)(struct clocksource *cs);
+	unsigned long flags;
+	void (*suspend)(struct clocksource *cs);
+	void (*resume)(struct clocksource *cs);
 
 #ifdef CONFIG_CLOCKSOURCE_WATCHDOG
 	/* Watchdog related data, used by the framework */
 	struct list_head wd_list;
 	cycle_t wd_last;
 #endif
-};
+} ____cacheline_aligned;
 
 /*
  * Clock source flags bits::
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 0d74b9b..22a9da9 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -194,6 +194,70 @@ void clockevents_register_device(struct clock_event_device *dev)
 }
 EXPORT_SYMBOL_GPL(clockevents_register_device);
 
+static void clockevents_config(struct clock_event_device *dev,
+			       u32 freq)
+{
+	unsigned long sec;
+
+	if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
+		return;
+
+	/*
+	 * Calculate the maximum number of seconds we can sleep. Limit
+	 * to 10 minutes for hardware which can program more than
+	 * 32bit ticks so we still get reasonable conversion values.
+	 */
+	sec = dev->max_delta_ticks;
+	do_div(sec, freq);
+	if (!sec)
+		sec = 1;
+	else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
+		sec = 600;
+
+	clockevents_calc_mult_shift(dev, freq, sec);
+	dev->min_delta_ns = clockevent_delta2ns(dev->min_delta_ticks, dev);
+	dev->max_delta_ns = clockevent_delta2ns(dev->max_delta_ticks, dev);
+}
+
+/**
+ * clockevents_config_and_register - Configure and register a clock event device
+ * @dev:	device to register
+ * @freq:	The clock frequency
+ * @min_delta:	The minimum clock ticks to program in oneshot mode
+ * @max_delta:	The maximum clock ticks to program in oneshot mode
+ *
+ * min/max_delta can be 0 for devices which do not support oneshot mode.
+ */
+void clockevents_config_and_register(struct clock_event_device *dev,
+				     u32 freq, unsigned long min_delta,
+				     unsigned long max_delta)
+{
+	dev->min_delta_ticks = min_delta;
+	dev->max_delta_ticks = max_delta;
+	clockevents_config(dev, freq);
+	clockevents_register_device(dev);
+}
+
+/**
+ * clockevents_update_freq - Update frequency and reprogram a clock event device.
+ * @dev:	device to modify
+ * @freq:	new device frequency
+ *
+ * Reconfigure and reprogram a clock event device in oneshot
+ * mode. Must be called on the cpu for which the device delivers per
+ * cpu timer events with interrupts disabled!  Returns 0 on success,
+ * -ETIME when the event is in the past.
+ */
+int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
+{
+	clockevents_config(dev, freq);
+
+	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
+		return 0;
+
+	return clockevents_program_event(dev, dev->next_event, ktime_get());
+}
+
 /*
  * Noop handler when we shut down an event device
  */
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 0e17c10..d9d5f8c 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -626,19 +626,6 @@ static void clocksource_enqueue(struct clocksource *cs)
 	list_add(&cs->list, entry);
 }
 
-
-/*
- * Maximum time we expect to go between ticks. This includes idle
- * tickless time. It provides the trade off between selecting a
- * mult/shift pair that is very precise but can only handle a short
- * period of time, vs. a mult/shift pair that can handle long periods
- * of time but isn't as precise.
- *
- * This is a subsystem constant, and actual hardware limitations
- * may override it (ie: clocksources that wrap every 3 seconds).
- */
-#define MAX_UPDATE_LENGTH 5 /* Seconds */
-
 /**
  * __clocksource_updatefreq_scale - Used update clocksource with new freq
  * @t:		clocksource to be registered
@@ -652,15 +639,28 @@ static void clocksource_enqueue(struct clocksource *cs)
  */
 void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq)
 {
+	unsigned long sec;
+
 	/*
-	 * Ideally we want to use  some of the limits used in
-	 * clocksource_max_deferment, to provide a more informed
-	 * MAX_UPDATE_LENGTH. But for now this just gets the
-	 * register interface working properly.
+	 * Calc the maximum number of seconds which we can run before
+	 * wrapping around. For clocksources which have a mask > 32bit
+	 * we need to limit the max sleep time to have a good
+	 * conversion precision. 10 minutes is still a reasonable
+	 * amount. That results in a shift value of 24 for a
+	 * clocksource with mask >= 40bit and f >= 4GHz. That maps to
+	 * ~ 0.06ppm granularity for NTP. We apply the same 12.5%
+	 * margin as we do in clocksource_max_deferment()
 	 */
+	sec = (cs->mask - (cs->mask >> 5));
+	do_div(sec, freq);
+	do_div(sec, scale);
+	if (!sec)
+		sec = 1;
+	else if (sec > 600 && cs->mask > UINT_MAX)
+		sec = 600;
+
 	clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
-				      NSEC_PER_SEC/scale,
-				      MAX_UPDATE_LENGTH*scale);
+			       NSEC_PER_SEC / scale, sec * scale);
 	cs->max_idle_ns = clocksource_max_deferment(cs);
 }
 EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale);