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author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
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committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /kernel/time/tick-common.c | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
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Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'kernel/time/tick-common.c')
-rw-r--r-- | kernel/time/tick-common.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c new file mode 100644 index 00000000..da6c9eca --- /dev/null +++ b/kernel/time/tick-common.c @@ -0,0 +1,419 @@ +/* + * linux/kernel/time/tick-common.c + * + * This file contains the base functions to manage periodic tick + * related events. + * + * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> + * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar + * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner + * + * This code is licenced under the GPL version 2. For details see + * kernel-base/COPYING. + */ +#include <linux/cpu.h> +#include <linux/err.h> +#include <linux/hrtimer.h> +#include <linux/interrupt.h> +#include <linux/percpu.h> +#include <linux/profile.h> +#include <linux/sched.h> + +#include <asm/irq_regs.h> + +#include "tick-internal.h" + +/* + * Tick devices + */ +DEFINE_PER_CPU(struct tick_device, tick_cpu_device); +/* + * Tick next event: keeps track of the tick time + */ +ktime_t tick_next_period; +ktime_t tick_period; +int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT; +static DEFINE_RAW_SPINLOCK(tick_device_lock); + +/* + * Debugging: see timer_list.c + */ +struct tick_device *tick_get_device(int cpu) +{ + return &per_cpu(tick_cpu_device, cpu); +} + +/** + * tick_is_oneshot_available - check for a oneshot capable event device + */ +int tick_is_oneshot_available(void) +{ + struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); + + if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT)) + return 0; + if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) + return 1; + return tick_broadcast_oneshot_available(); +} + +/* + * Periodic tick + */ +static void tick_periodic(int cpu) +{ + if (tick_do_timer_cpu == cpu) { + write_seqlock(&xtime_lock); + + /* Keep track of the next tick event */ + tick_next_period = ktime_add(tick_next_period, tick_period); + + do_timer(1); + write_sequnlock(&xtime_lock); + } + + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); +} + +/* + * Event handler for periodic ticks + */ +void tick_handle_periodic(struct clock_event_device *dev) +{ + int cpu = smp_processor_id(); + ktime_t next; + + tick_periodic(cpu); + + if (dev->mode != CLOCK_EVT_MODE_ONESHOT) + return; + /* + * Setup the next period for devices, which do not have + * periodic mode: + */ + next = ktime_add(dev->next_event, tick_period); + for (;;) { + if (!clockevents_program_event(dev, next, false)) + return; + /* + * Have to be careful here. If we're in oneshot mode, + * before we call tick_periodic() in a loop, we need + * to be sure we're using a real hardware clocksource. + * Otherwise we could get trapped in an infinite + * loop, as the tick_periodic() increments jiffies, + * when then will increment time, posibly causing + * the loop to trigger again and again. + */ + if (timekeeping_valid_for_hres()) + tick_periodic(cpu); + next = ktime_add(next, tick_period); + } +} + +/* + * Setup the device for a periodic tick + */ +void tick_setup_periodic(struct clock_event_device *dev, int broadcast) +{ + tick_set_periodic_handler(dev, broadcast); + + /* Broadcast setup ? */ + if (!tick_device_is_functional(dev)) + return; + + if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && + !tick_broadcast_oneshot_active()) { + clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); + } else { + unsigned long seq; + ktime_t next; + + do { + seq = read_seqbegin(&xtime_lock); + next = tick_next_period; + } while (read_seqretry(&xtime_lock, seq)); + + clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); + + for (;;) { + if (!clockevents_program_event(dev, next, false)) + return; + next = ktime_add(next, tick_period); + } + } +} + +/* + * Setup the tick device + */ +static void tick_setup_device(struct tick_device *td, + struct clock_event_device *newdev, int cpu, + const struct cpumask *cpumask) +{ + ktime_t next_event; + void (*handler)(struct clock_event_device *) = NULL; + + /* + * First device setup ? + */ + if (!td->evtdev) { + /* + * If no cpu took the do_timer update, assign it to + * this cpu: + */ + if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { + tick_do_timer_cpu = cpu; + tick_next_period = ktime_get(); + tick_period = ktime_set(0, NSEC_PER_SEC / HZ); + } + + /* + * Startup in periodic mode first. + */ + td->mode = TICKDEV_MODE_PERIODIC; + } else { + handler = td->evtdev->event_handler; + next_event = td->evtdev->next_event; + td->evtdev->event_handler = clockevents_handle_noop; + } + + td->evtdev = newdev; + + /* + * When the device is not per cpu, pin the interrupt to the + * current cpu: + */ + if (!cpumask_equal(newdev->cpumask, cpumask)) + irq_set_affinity(newdev->irq, cpumask); + + /* + * When global broadcasting is active, check if the current + * device is registered as a placeholder for broadcast mode. + * This allows us to handle this x86 misfeature in a generic + * way. + */ + if (tick_device_uses_broadcast(newdev, cpu)) + return; + + if (td->mode == TICKDEV_MODE_PERIODIC) + tick_setup_periodic(newdev, 0); + else + tick_setup_oneshot(newdev, handler, next_event); +} + +/* + * Check, if the new registered device should be used. + */ +static int tick_check_new_device(struct clock_event_device *newdev) +{ + struct clock_event_device *curdev; + struct tick_device *td; + int cpu, ret = NOTIFY_OK; + unsigned long flags; + + raw_spin_lock_irqsave(&tick_device_lock, flags); + + cpu = smp_processor_id(); + if (!cpumask_test_cpu(cpu, newdev->cpumask)) + goto out_bc; + + td = &per_cpu(tick_cpu_device, cpu); + curdev = td->evtdev; + + /* cpu local device ? */ + if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) { + + /* + * If the cpu affinity of the device interrupt can not + * be set, ignore it. + */ + if (!irq_can_set_affinity(newdev->irq)) + goto out_bc; + + /* + * If we have a cpu local device already, do not replace it + * by a non cpu local device + */ + if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) + goto out_bc; + } + + /* + * If we have an active device, then check the rating and the oneshot + * feature. + */ + if (curdev) { + /* + * Prefer one shot capable devices ! + */ + if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) && + !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) + goto out_bc; + /* + * Check the rating + */ + if (curdev->rating >= newdev->rating) + goto out_bc; + } + + /* + * Replace the eventually existing device by the new + * device. If the current device is the broadcast device, do + * not give it back to the clockevents layer ! + */ + if (tick_is_broadcast_device(curdev)) { + clockevents_shutdown(curdev); + curdev = NULL; + } + clockevents_exchange_device(curdev, newdev); + tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); + if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) + tick_oneshot_notify(); + + raw_spin_unlock_irqrestore(&tick_device_lock, flags); + return NOTIFY_STOP; + +out_bc: + /* + * Can the new device be used as a broadcast device ? + */ + if (tick_check_broadcast_device(newdev)) + ret = NOTIFY_STOP; + + raw_spin_unlock_irqrestore(&tick_device_lock, flags); + + return ret; +} + +/* + * Transfer the do_timer job away from a dying cpu. + * + * Called with interrupts disabled. + */ +static void tick_handover_do_timer(int *cpup) +{ + if (*cpup == tick_do_timer_cpu) { + int cpu = cpumask_first(cpu_online_mask); + + tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu : + TICK_DO_TIMER_NONE; + } +} + +/* + * Shutdown an event device on a given cpu: + * + * This is called on a life CPU, when a CPU is dead. So we cannot + * access the hardware device itself. + * We just set the mode and remove it from the lists. + */ +static void tick_shutdown(unsigned int *cpup) +{ + struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); + struct clock_event_device *dev = td->evtdev; + unsigned long flags; + + raw_spin_lock_irqsave(&tick_device_lock, flags); + td->mode = TICKDEV_MODE_PERIODIC; + if (dev) { + /* + * Prevent that the clock events layer tries to call + * the set mode function! + */ + dev->mode = CLOCK_EVT_MODE_UNUSED; + clockevents_exchange_device(dev, NULL); + td->evtdev = NULL; + } + raw_spin_unlock_irqrestore(&tick_device_lock, flags); +} + +static void tick_suspend(void) +{ + struct tick_device *td = &__get_cpu_var(tick_cpu_device); + unsigned long flags; + + raw_spin_lock_irqsave(&tick_device_lock, flags); + clockevents_shutdown(td->evtdev); + raw_spin_unlock_irqrestore(&tick_device_lock, flags); +} + +static void tick_resume(void) +{ + struct tick_device *td = &__get_cpu_var(tick_cpu_device); + unsigned long flags; + int broadcast = tick_resume_broadcast(); + + raw_spin_lock_irqsave(&tick_device_lock, flags); + clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME); + + if (!broadcast) { + if (td->mode == TICKDEV_MODE_PERIODIC) + tick_setup_periodic(td->evtdev, 0); + else + tick_resume_oneshot(); + } + raw_spin_unlock_irqrestore(&tick_device_lock, flags); +} + +/* + * Notification about clock event devices + */ +static int tick_notify(struct notifier_block *nb, unsigned long reason, + void *dev) +{ + switch (reason) { + + case CLOCK_EVT_NOTIFY_ADD: + return tick_check_new_device(dev); + + case CLOCK_EVT_NOTIFY_BROADCAST_ON: + case CLOCK_EVT_NOTIFY_BROADCAST_OFF: + case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: + tick_broadcast_on_off(reason, dev); + break; + + case CLOCK_EVT_NOTIFY_BROADCAST_ENTER: + case CLOCK_EVT_NOTIFY_BROADCAST_EXIT: + tick_broadcast_oneshot_control(reason); + break; + + case CLOCK_EVT_NOTIFY_CPU_DYING: + tick_handover_do_timer(dev); + break; + + case CLOCK_EVT_NOTIFY_CPU_DEAD: + tick_shutdown_broadcast_oneshot(dev); + tick_shutdown_broadcast(dev); + tick_shutdown(dev); + break; + + case CLOCK_EVT_NOTIFY_SUSPEND: + tick_suspend(); + tick_suspend_broadcast(); + break; + + case CLOCK_EVT_NOTIFY_RESUME: + tick_resume(); + break; + + default: + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block tick_notifier = { + .notifier_call = tick_notify, +}; + +/** + * tick_init - initialize the tick control + * + * Register the notifier with the clockevents framework + */ +void __init tick_init(void) +{ + clockevents_register_notifier(&tick_notifier); +} |