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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-19 17:44:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-19 17:44:40 -0700
commit7e6628e4bcb3b3546c625ec63ca724f28ab14f0c (patch)
tree111a94cefa9d800ec5c5e59520f4b5d1880965d0
parent0f1bdc1815c4cb29b3cd71a7091b478e426faa0b (diff)
parentab0e08f15d23628dd8d50bf6ce1a935a8840c7dc (diff)
Merge branch 'timers-clockevents-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-clockevents-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: hpet: Cleanup the clockevents init and register code x86: Convert PIT to clockevents_config_and_register() clockevents: Provide interface to reconfigure an active clock event device clockevents: Provide combined configure and register function clockevents: Restructure clock_event_device members clocksource: Get rid of the hardcoded 5 seconds sleep time limit clocksource: Restructure clocksource struct members
-rw-r--r--arch/x86/kernel/hpet.c72
-rw-r--r--arch/x86/kernel/i8253.c6
-rw-r--r--include/linux/clockchips.h56
-rw-r--r--include/linux/clocksource.h32
-rw-r--r--kernel/time/clockevents.c64
-rw-r--r--kernel/time/clocksource.c38
6 files changed, 148 insertions, 120 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index bfe8f729e086..6781765b3a0d 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 577e90cadaeb..fb66dc9e36cb 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 fc53492b6ad7..d6733e27af34 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 0fb0b7e79394..c918fbd33ee5 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 0d74b9ba90c8..22a9da9a9c96 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 0e17c10f8a9d..d9d5f8c885f6 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);