diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index bfe8f729e0861a9edf636e2acfddcaec46261ca5..6781765b3a0df0317fc67a0051fb459aa3c15d01 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, }; @@ -289,29 +288,13 @@ static void hpet_legacy_clockevent_register(void) /* Start HPET legacy interrupts */ 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()) @@ -883,6 +835,14 @@ int __init hpet_enable(void) if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD) 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 577e90cadaebbd4acb68d7b3065f9f5f6d9eb7e6..fb66dc9e36cba31bb190a0a47fb120eaf4cc863e 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 fc53492b6ad7fb67e904e88d2f02d184771a326e..d6733e27af349349bdcf97f1a7674a530bc99e2f 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 0fb0b7e793947d2b2255119b54fea0662cb6b5c6..c918fbd33ee58e33f9560adbcc61c9901048ca78 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 0d74b9ba90c84e0474b28a71ea9d43b76e4263f9..22a9da9a9c96918861caea99521285e53572bab0 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 0e17c10f8a9daae8fdd8c665d69788670549b1c0..d9d5f8c885f65d6ac1c942412c74cacfbabe8626 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);