diff options
Diffstat (limited to 'kernel/time/clockevents.c')
| -rw-r--r-- | kernel/time/clockevents.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c new file mode 100644 index 0000000..f8d9680 --- /dev/null +++ b/kernel/time/clockevents.c @@ -0,0 +1,250 @@ +/* + * linux/kernel/time/clockevents.c + * + * This file contains functions which manage clock event devices. + * + * 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/clockchips.h> +#include <linux/hrtimer.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/notifier.h> +#include <linux/smp.h> +#include <linux/sysdev.h> + +/* The registered clock event devices */ +static LIST_HEAD(clockevent_devices); +static LIST_HEAD(clockevents_released); + +/* Notification for clock events */ +static RAW_NOTIFIER_HEAD(clockevents_chain); + +/* Protection for the above */ +static DEFINE_SPINLOCK(clockevents_lock); + +/** + * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds + * @latch: value to convert + * @evt: pointer to clock event device descriptor + * + * Math helper, returns latch value converted to nanoseconds (bound checked) + */ +unsigned long clockevent_delta2ns(unsigned long latch, + struct clock_event_device *evt) +{ + u64 clc = ((u64) latch << evt->shift); + + if (unlikely(!evt->mult)) { + evt->mult = 1; + WARN_ON(1); + } + + do_div(clc, evt->mult); + if (clc < 1000) + clc = 1000; + if (clc > LONG_MAX) + clc = LONG_MAX; + + return (unsigned long) clc; +} + +/** + * clockevents_set_mode - set the operating mode of a clock event device + * @dev: device to modify + * @mode: new mode + * + * Must be called with interrupts disabled ! + */ +void clockevents_set_mode(struct clock_event_device *dev, + enum clock_event_mode mode) +{ + if (dev->mode != mode) { + dev->set_mode(mode, dev); + dev->mode = mode; + } +} + +/** + * clockevents_shutdown - shutdown the device and clear next_event + * @dev: device to shutdown + */ +void clockevents_shutdown(struct clock_event_device *dev) +{ + clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); + dev->next_event.tv64 = KTIME_MAX; +} + +/** + * clockevents_program_event - Reprogram the clock event device. + * @expires: absolute expiry time (monotonic clock) + * + * Returns 0 on success, -ETIME when the event is in the past. + */ +int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, + ktime_t now) +{ + unsigned long long clc; + int64_t delta; + + if (unlikely(expires.tv64 < 0)) { + WARN_ON_ONCE(1); + return -ETIME; + } + + delta = ktime_to_ns(ktime_sub(expires, now)); + + if (delta <= 0) + return -ETIME; + + dev->next_event = expires; + + if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) + return 0; + + if (delta > dev->max_delta_ns) + delta = dev->max_delta_ns; + if (delta < dev->min_delta_ns) + delta = dev->min_delta_ns; + + clc = delta * dev->mult; + clc >>= dev->shift; + + return dev->set_next_event((unsigned long) clc, dev); +} + +/** + * clockevents_register_notifier - register a clock events change listener + */ +int clockevents_register_notifier(struct notifier_block *nb) +{ + int ret; + + spin_lock(&clockevents_lock); + ret = raw_notifier_chain_register(&clockevents_chain, nb); + spin_unlock(&clockevents_lock); + + return ret; +} + +/* + * Notify about a clock event change. Called with clockevents_lock + * held. + */ +static void clockevents_do_notify(unsigned long reason, void *dev) +{ + raw_notifier_call_chain(&clockevents_chain, reason, dev); +} + +/* + * Called after a notify add to make devices available which were + * released from the notifier call. + */ +static void clockevents_notify_released(void) +{ + struct clock_event_device *dev; + + while (!list_empty(&clockevents_released)) { + dev = list_entry(clockevents_released.next, + struct clock_event_device, list); + list_del(&dev->list); + list_add(&dev->list, &clockevent_devices); + clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); + } +} + +/** + * clockevents_register_device - register a clock event device + * @dev: device to register + */ +void clockevents_register_device(struct clock_event_device *dev) +{ + BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); + /* + * A nsec2cyc multiplicator of 0 is invalid and we'd crash + * on it, so fix it up and emit a warning: + */ + if (unlikely(!dev->mult)) { + dev->mult = 1; + WARN_ON(1); + } + + spin_lock(&clockevents_lock); + + list_add(&dev->list, &clockevent_devices); + clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); + clockevents_notify_released(); + + spin_unlock(&clockevents_lock); +} + +/* + * Noop handler when we shut down an event device + */ +void clockevents_handle_noop(struct clock_event_device *dev) +{ +} + +/** + * clockevents_exchange_device - release and request clock devices + * @old: device to release (can be NULL) + * @new: device to request (can be NULL) + * + * Called from the notifier chain. clockevents_lock is held already + */ +void clockevents_exchange_device(struct clock_event_device *old, + struct clock_event_device *new) +{ + unsigned long flags; + + local_irq_save(flags); + /* + * Caller releases a clock event device. We queue it into the + * released list and do a notify add later. + */ + if (old) { + clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); + list_del(&old->list); + list_add(&old->list, &clockevents_released); + } + + if (new) { + BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); + clockevents_shutdown(new); + } + local_irq_restore(flags); +} + +#ifdef CONFIG_GENERIC_CLOCKEVENTS +/** + * clockevents_notify - notification about relevant events + */ +void clockevents_notify(unsigned long reason, void *arg) +{ + struct list_head *node, *tmp; + + spin_lock(&clockevents_lock); + clockevents_do_notify(reason, arg); + + switch (reason) { + case CLOCK_EVT_NOTIFY_CPU_DEAD: + /* + * Unregister the clock event devices which were + * released from the users in the notify chain. + */ + list_for_each_safe(node, tmp, &clockevents_released) + list_del(node); + break; + default: + break; + } + spin_unlock(&clockevents_lock); +} +EXPORT_SYMBOL_GPL(clockevents_notify); +#endif |
