kernel/time/clockevents.c - LeafOS-Devices/android_kernel_samsung_universal7904 - Gitiles

 /*
  * 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/smp.h>
 #include <linux/device.h>
 #include <linux/exynos-ss.h>

 #include "tick-internal.h"

 /* The registered clock event devices */
 static LIST_HEAD(clockevent_devices);
 static LIST_HEAD(clockevents_released);
 /* Protection for the above */
 static DEFINE_RAW_SPINLOCK(clockevents_lock);
 /* Protection for unbind operations */
 static DEFINE_MUTEX(clockevents_mutex);

 struct ce_unbind {
 	struct clock_event_device *ce;
 	int res;
 };

 static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
 			bool ismax)
 {
 	u64 clc = (u64) latch << evt->shift;
 	u64 rnd;

 	if (unlikely(!evt->mult)) {
 		evt->mult = 1;
 		WARN_ON(1);
 	}
 	rnd = (u64) evt->mult - 1;

 	/*
 	 * Upper bound sanity check. If the backwards conversion is
 	 * not equal latch, we know that the above shift overflowed.
 	 */
 	if ((clc >> evt->shift) != (u64)latch)
 		clc = ~0ULL;

 	/*
 	 * Scaled math oddities:
 	 *
 	 * For mult <= (1 << shift) we can safely add mult - 1 to
 	 * prevent integer rounding loss. So the backwards conversion
 	 * from nsec to device ticks will be correct.
 	 *
 	 * For mult > (1 << shift), i.e. device frequency is > 1GHz we
 	 * need to be careful. Adding mult - 1 will result in a value
 	 * which when converted back to device ticks can be larger
 	 * than latch by up to (mult - 1) >> shift. For the min_delta
 	 * calculation we still want to apply this in order to stay
 	 * above the minimum device ticks limit. For the upper limit
 	 * we would end up with a latch value larger than the upper
 	 * limit of the device, so we omit the add to stay below the
 	 * device upper boundary.
 	 *
 	 * Also omit the add if it would overflow the u64 boundary.
 	 */
 	if ((~0ULL - clc > rnd) &&
 	    (!ismax || evt->mult <= (1ULL << evt->shift)))
 		clc += rnd;

 	do_div(clc, evt->mult);

 	/* Deltas less than 1usec are pointless noise */
 	return clc > 1000 ? clc : 1000;
 }

 /**
  * 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)
  */
 u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
 {
 	return cev_delta2ns(latch, evt, false);
 }
 EXPORT_SYMBOL_GPL(clockevent_delta2ns);

 static int __clockevents_switch_state(struct clock_event_device *dev,
 				      enum clock_event_state state)
 {
 	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
 		return 0;

 	/* Transition with new state-specific callbacks */
 	switch (state) {
 	case CLOCK_EVT_STATE_DETACHED:
 		/* The clockevent device is getting replaced. Shut it down. */

 	case CLOCK_EVT_STATE_SHUTDOWN:
 		if (dev->set_state_shutdown)
 			return dev->set_state_shutdown(dev);
 		return 0;

 	case CLOCK_EVT_STATE_PERIODIC:
 		/* Core internal bug */
 		if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
 			return -ENOSYS;
 		if (dev->set_state_periodic)
 			return dev->set_state_periodic(dev);
 		return 0;

 	case CLOCK_EVT_STATE_ONESHOT:
 		/* Core internal bug */
 		if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
 			return -ENOSYS;
 		if (dev->set_state_oneshot)
 			return dev->set_state_oneshot(dev);
 		return 0;

 	case CLOCK_EVT_STATE_ONESHOT_STOPPED:
 		/* Core internal bug */
 		if (WARN_ONCE(!clockevent_state_oneshot(dev),
 			      "Current state: %d\n",
 			      clockevent_get_state(dev)))
 			return -EINVAL;

 		if (dev->set_state_oneshot_stopped)
 			return dev->set_state_oneshot_stopped(dev);
 		else
 			return -ENOSYS;

 	default:
 		return -ENOSYS;
 	}
 }

 /**
  * clockevents_switch_state - set the operating state of a clock event device
  * @dev:	device to modify
  * @state:	new state
  *
  * Must be called with interrupts disabled !
  */
 void clockevents_switch_state(struct clock_event_device *dev,
 			      enum clock_event_state state)
 {
 	if (clockevent_get_state(dev) != state) {
 		if (__clockevents_switch_state(dev, state))
 			return;

 		clockevent_set_state(dev, state);

 		/*
 		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
 		 * on it, so fix it up and emit a warning:
 		 */
 		if (clockevent_state_oneshot(dev)) {
 			if (unlikely(!dev->mult)) {
 				dev->mult = 1;
 				WARN_ON(1);
 			}
 		}
 	}
 }

 /**
  * clockevents_shutdown - shutdown the device and clear next_event
  * @dev:	device to shutdown
  */
 void clockevents_shutdown(struct clock_event_device *dev)
 {
 	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
 	dev->next_event.tv64 = KTIME_MAX;
 }

 /**
  * clockevents_tick_resume -	Resume the tick device before using it again
  * @dev:			device to resume
  */
 int clockevents_tick_resume(struct clock_event_device *dev)
 {
 	int ret = 0;

 	if (dev->tick_resume)
 		ret = dev->tick_resume(dev);

 	return ret;
 }

 #ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST

 /* Limit min_delta to a jiffie */
 #define MIN_DELTA_LIMIT		(NSEC_PER_SEC / HZ)

 /**
  * clockevents_increase_min_delta - raise minimum delta of a clock event device
  * @dev:       device to increase the minimum delta
  *
  * Returns 0 on success, -ETIME when the minimum delta reached the limit.
  */
 static int clockevents_increase_min_delta(struct clock_event_device *dev)
 {
 	/* Nothing to do if we already reached the limit */
 	if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
 		printk_deferred(KERN_WARNING
 				"CE: Reprogramming failure. Giving up\n");
 		dev->next_event.tv64 = KTIME_MAX;
 		return -ETIME;
 	}

 	if (dev->min_delta_ns < 5000)
 		dev->min_delta_ns = 5000;
 	else
 		dev->min_delta_ns += dev->min_delta_ns >> 1;

 	if (dev->min_delta_ns > MIN_DELTA_LIMIT)
 		dev->min_delta_ns = MIN_DELTA_LIMIT;

 	printk_deferred(KERN_WARNING
 			"CE: %s increased min_delta_ns to %llu nsec\n",
 			dev->name ? dev->name : "?",
 			(unsigned long long) dev->min_delta_ns);
 	return 0;
 }

 /**
  * clockevents_program_min_delta - Set clock event device to the minimum delay.
  * @dev:	device to program
  *
  * Returns 0 on success, -ETIME when the retry loop failed.
  */
 static int clockevents_program_min_delta(struct clock_event_device *dev)
 {
 	unsigned long long clc;
 	int64_t delta;
 	int i;

 	for (i = 0;;) {
 		delta = dev->min_delta_ns;
 		dev->next_event = ktime_add_ns(ktime_get(), delta);

 		if (clockevent_state_shutdown(dev))
 			return 0;

 		dev->retries++;
 		clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 		exynos_ss_clockevent(clc, delta, &dev->next_event);
 		if (dev->set_next_event((unsigned long) clc, dev) == 0)
 			return 0;

 		if (++i > 2) {
 			/*
 			 * We tried 3 times to program the device with the
 			 * given min_delta_ns. Try to increase the minimum
 			 * delta, if that fails as well get out of here.
 			 */
 			if (clockevents_increase_min_delta(dev))
 				return -ETIME;
 			i = 0;
 		}
 	}
 }

 #else  /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */

 /**
  * clockevents_program_min_delta - Set clock event device to the minimum delay.
  * @dev:	device to program
  *
  * Returns 0 on success, -ETIME when the retry loop failed.
  */
 static int clockevents_program_min_delta(struct clock_event_device *dev)
 {
 	unsigned long long clc;
 	int64_t delta;

 	delta = dev->min_delta_ns;
 	dev->next_event = ktime_add_ns(ktime_get(), delta);

 	if (clockevent_state_shutdown(dev))
 		return 0;

 	dev->retries++;
 	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 	exynos_ss_clockevent(clc, delta, &dev->next_event);
 	return dev->set_next_event((unsigned long) clc, dev);
 }

 #endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */

 /**
  * clockevents_program_event - Reprogram the clock event device.
  * @dev:	device to program
  * @expires:	absolute expiry time (monotonic clock)
  * @force:	program minimum delay if expires can not be set
  *
  * Returns 0 on success, -ETIME when the event is in the past.
  */
 int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
 			      bool force)
 {
 	unsigned long long clc;
 	int64_t delta;
 	int rc;

 	if (unlikely(expires.tv64 < 0)) {
 		WARN_ON_ONCE(1);
 		return -ETIME;
 	}

 	dev->next_event = expires;

 	if (clockevent_state_shutdown(dev))
 		return 0;

 	/* We must be in ONESHOT state here */
 	WARN_ONCE(!clockevent_state_oneshot(dev), "Current state: %d\n",
 		  clockevent_get_state(dev));

 	/* Shortcut for clockevent devices that can deal with ktime. */
 	if (dev->features & CLOCK_EVT_FEAT_KTIME)
 		return dev->set_next_ktime(expires, dev);

 	delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
 	if (delta <= 0)
 		return force ? clockevents_program_min_delta(dev) : -ETIME;

 	delta = min(delta, (int64_t) dev->max_delta_ns);
 	delta = max(delta, (int64_t) dev->min_delta_ns);

 	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 	exynos_ss_clockevent(clc, delta, &dev->next_event);
 	rc = dev->set_next_event((unsigned long) clc, dev);

 	return (rc && force) ? clockevents_program_min_delta(dev) : rc;
 }

 /*
  * 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);
 		tick_check_new_device(dev);
 	}
 }

 /*
  * Try to install a replacement clock event device
  */
 static int clockevents_replace(struct clock_event_device *ced)
 {
 	struct clock_event_device *dev, *newdev = NULL;

 	list_for_each_entry(dev, &clockevent_devices, list) {
 		if (dev == ced || !clockevent_state_detached(dev))
 			continue;

 		if (!tick_check_replacement(newdev, dev))
 			continue;

 		if (!try_module_get(dev->owner))
 			continue;

 		if (newdev)
 			module_put(newdev->owner);
 		newdev = dev;
 	}
 	if (newdev) {
 		tick_install_replacement(newdev);
 		list_del_init(&ced->list);
 	}
 	return newdev ? 0 : -EBUSY;
 }

 /*
  * Called with clockevents_mutex and clockevents_lock held
  */
 static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
 {
 	/* Fast track. Device is unused */
 	if (clockevent_state_detached(ced)) {
 		list_del_init(&ced->list);
 		return 0;
 	}

 	return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
 }

 /*
  * SMP function call to unbind a device
  */
 static void __clockevents_unbind(void *arg)
 {
 	struct ce_unbind *cu = arg;
 	int res;

 	raw_spin_lock(&clockevents_lock);
 	res = __clockevents_try_unbind(cu->ce, smp_processor_id());
 	if (res == -EAGAIN)
 		res = clockevents_replace(cu->ce);
 	cu->res = res;
 	raw_spin_unlock(&clockevents_lock);
 }

 /*
  * Issues smp function call to unbind a per cpu device. Called with
  * clockevents_mutex held.
  */
 static int clockevents_unbind(struct clock_event_device *ced, int cpu)
 {
 	struct ce_unbind cu = { .ce = ced, .res = -ENODEV };

 	smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
 	return cu.res;
 }

 /*
  * Unbind a clockevents device.
  */
 int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
 {
 	int ret;

 	mutex_lock(&clockevents_mutex);
 	ret = clockevents_unbind(ced, cpu);
 	mutex_unlock(&clockevents_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clockevents_unbind_device);

 /**
  * clockevents_register_device - register a clock event device
  * @dev:	device to register
  */
 void clockevents_register_device(struct clock_event_device *dev)
 {
 	unsigned long flags;

 	/* Initialize state to DETACHED */
 	clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);

 	if (!dev->cpumask) {
 		WARN_ON(num_possible_cpus() > 1);
 		dev->cpumask = cpumask_of(smp_processor_id());
 	}

 	raw_spin_lock_irqsave(&clockevents_lock, flags);

 	list_add(&dev->list, &clockevent_devices);
 	tick_check_new_device(dev);
 	clockevents_notify_released();

 	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
 }
 EXPORT_SYMBOL_GPL(clockevents_register_device);

 void clockevents_config(struct clock_event_device *dev, u32 freq)
 {
 	u64 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 = cev_delta2ns(dev->min_delta_ticks, dev, false);
 	dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
 }

 /**
  * 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);
 }
 EXPORT_SYMBOL_GPL(clockevents_config_and_register);

 int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
 	clockevents_config(dev, freq);

 	if (clockevent_state_oneshot(dev))
 		return clockevents_program_event(dev, dev->next_event, false);

 	if (clockevent_state_periodic(dev))
 		return __clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);

 	return 0;
 }

 /**
  * 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. If called for the broadcast device the core takes
  * care of serialization.
  *
  * Returns 0 on success, -ETIME when the event is in the past.
  */
 int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 {
 	unsigned long flags;
 	int ret;

 	local_irq_save(flags);
 	ret = tick_broadcast_update_freq(dev, freq);
 	if (ret == -ENODEV)
 		ret = __clockevents_update_freq(dev, freq);
 	local_irq_restore(flags);
 	return ret;
 }

 /*
  * 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 various tick functions with clockevents_lock held and
  * interrupts disabled.
  */
 void clockevents_exchange_device(struct clock_event_device *old,
 				 struct clock_event_device *new)
 {
 	/*
 	 * Caller releases a clock event device. We queue it into the
 	 * released list and do a notify add later.
 	 */
 	if (old) {
 		module_put(old->owner);
 		clockevents_switch_state(old, CLOCK_EVT_STATE_DETACHED);
 		list_del(&old->list);
 		list_add(&old->list, &clockevents_released);
 	}

 	if (new) {
 		BUG_ON(!clockevent_state_detached(new));
 		clockevents_shutdown(new);
 	}
 }

 /**
  * clockevents_suspend - suspend clock devices
  */
 void clockevents_suspend(void)
 {
 	struct clock_event_device *dev;

 	list_for_each_entry_reverse(dev, &clockevent_devices, list)
 		if (dev->suspend && !clockevent_state_detached(dev))
 			dev->suspend(dev);
 }

 /**
  * clockevents_resume - resume clock devices
  */
 void clockevents_resume(void)
 {
 	struct clock_event_device *dev;

 	list_for_each_entry(dev, &clockevent_devices, list)
 		if (dev->resume && !clockevent_state_detached(dev))
 			dev->resume(dev);
 }

 #ifdef CONFIG_HOTPLUG_CPU
 /**
  * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
  */
 void tick_cleanup_dead_cpu(int cpu)
 {
 	struct clock_event_device *dev, *tmp;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&clockevents_lock, flags);

 	tick_shutdown_broadcast_oneshot(cpu);
 	tick_shutdown_broadcast(cpu);
 	tick_shutdown(cpu);
 	/*
 	 * Unregister the clock event devices which were
 	 * released from the users in the notify chain.
 	 */
 	list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
 		list_del(&dev->list);
 	/*
 	 * Now check whether the CPU has left unused per cpu devices
 	 */
 	list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
 		if (cpumask_test_cpu(cpu, dev->cpumask) &&
 		    cpumask_weight(dev->cpumask) == 1 &&
 		    !tick_is_broadcast_device(dev)) {
 			BUG_ON(!clockevent_state_detached(dev));
 			list_del(&dev->list);
 		}
 	}
 	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
 }
 #endif

 #ifdef CONFIG_SYSFS
 struct bus_type clockevents_subsys = {
 	.name		= "clockevents",
 	.dev_name       = "clockevent",
 };

 static DEFINE_PER_CPU(struct device, tick_percpu_dev);
 static struct tick_device *tick_get_tick_dev(struct device *dev);

 static ssize_t sysfs_show_current_tick_dev(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
 	struct tick_device *td;
 	ssize_t count = 0;

 	raw_spin_lock_irq(&clockevents_lock);
 	td = tick_get_tick_dev(dev);
 	if (td && td->evtdev)
 		count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
 	raw_spin_unlock_irq(&clockevents_lock);
 	return count;
 }
 static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);

 /* We don't support the abomination of removable broadcast devices */
 static ssize_t sysfs_unbind_tick_dev(struct device *dev,
 				     struct device_attribute *attr,
 				     const char *buf, size_t count)
 {
 	char name[CS_NAME_LEN];
 	ssize_t ret = sysfs_get_uname(buf, name, count);
 	struct clock_event_device *ce;

 	if (ret < 0)
 		return ret;

 	ret = -ENODEV;
 	mutex_lock(&clockevents_mutex);
 	raw_spin_lock_irq(&clockevents_lock);
 	list_for_each_entry(ce, &clockevent_devices, list) {
 		if (!strcmp(ce->name, name)) {
 			ret = __clockevents_try_unbind(ce, dev->id);
 			break;
 		}
 	}
 	raw_spin_unlock_irq(&clockevents_lock);
 	/*
 	 * We hold clockevents_mutex, so ce can't go away
 	 */
 	if (ret == -EAGAIN)
 		ret = clockevents_unbind(ce, dev->id);
 	mutex_unlock(&clockevents_mutex);
 	return ret ? ret : count;
 }
 static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);

 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 static struct device tick_bc_dev = {
 	.init_name	= "broadcast",
 	.id		= 0,
 	.bus		= &clockevents_subsys,
 };

 static struct tick_device *tick_get_tick_dev(struct device *dev)
 {
 	return dev == &tick_bc_dev ? tick_get_broadcast_device() :
 		&per_cpu(tick_cpu_device, dev->id);
 }

 static __init int tick_broadcast_init_sysfs(void)
 {
 	int err = device_register(&tick_bc_dev);

 	if (!err)
 		err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
 	return err;
 }
 #else
 static struct tick_device *tick_get_tick_dev(struct device *dev)
 {
 	return &per_cpu(tick_cpu_device, dev->id);
 }
 static inline int tick_broadcast_init_sysfs(void) { return 0; }
 #endif

 static int __init tick_init_sysfs(void)
 {
 	int cpu;

 	for_each_possible_cpu(cpu) {
 		struct device *dev = &per_cpu(tick_percpu_dev, cpu);
 		int err;

 		dev->id = cpu;
 		dev->bus = &clockevents_subsys;
 		err = device_register(dev);
 		if (!err)
 			err = device_create_file(dev, &dev_attr_current_device);
 		if (!err)
 			err = device_create_file(dev, &dev_attr_unbind_device);
 		if (err)
 			return err;
 	}
 	return tick_broadcast_init_sysfs();
 }

 static int __init clockevents_init_sysfs(void)
 {
 	int err = subsys_system_register(&clockevents_subsys, NULL);

 	if (!err)
 		err = tick_init_sysfs();
 	return err;
 }
 device_initcall(clockevents_init_sysfs);
 #endif /* SYSFS */
	/*
	* 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/smp.h>
	#include <linux/device.h>
	#include <linux/exynos-ss.h>

	#include "tick-internal.h"

	/* The registered clock event devices */
	static LIST_HEAD(clockevent_devices);
	static LIST_HEAD(clockevents_released);
	/* Protection for the above */
	static DEFINE_RAW_SPINLOCK(clockevents_lock);
	/* Protection for unbind operations */
	static DEFINE_MUTEX(clockevents_mutex);

	struct ce_unbind {
	struct clock_event_device *ce;
	int res;
	};

	static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
	bool ismax)
	{
	u64 clc = (u64) latch << evt->shift;
	u64 rnd;

	if (unlikely(!evt->mult)) {
	evt->mult = 1;
	WARN_ON(1);
	}
	rnd = (u64) evt->mult - 1;

	/*
	* Upper bound sanity check. If the backwards conversion is
	* not equal latch, we know that the above shift overflowed.
	*/
	if ((clc >> evt->shift) != (u64)latch)
	clc = ~0ULL;

	/*
	* Scaled math oddities:
	*
	* For mult <= (1 << shift) we can safely add mult - 1 to
	* prevent integer rounding loss. So the backwards conversion
	* from nsec to device ticks will be correct.
	*
	* For mult > (1 << shift), i.e. device frequency is > 1GHz we
	* need to be careful. Adding mult - 1 will result in a value
	* which when converted back to device ticks can be larger
	* than latch by up to (mult - 1) >> shift. For the min_delta
	* calculation we still want to apply this in order to stay
	* above the minimum device ticks limit. For the upper limit
	* we would end up with a latch value larger than the upper
	* limit of the device, so we omit the add to stay below the
	* device upper boundary.
	*
	* Also omit the add if it would overflow the u64 boundary.
	*/
	if ((~0ULL - clc > rnd) &&
	(!ismax \|\| evt->mult <= (1ULL << evt->shift)))
	clc += rnd;

	do_div(clc, evt->mult);

	/* Deltas less than 1usec are pointless noise */
	return clc > 1000 ? clc : 1000;
	}

	/**
	* 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)
	*/
	u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
	{
	return cev_delta2ns(latch, evt, false);
	}
	EXPORT_SYMBOL_GPL(clockevent_delta2ns);

	static int __clockevents_switch_state(struct clock_event_device *dev,
	enum clock_event_state state)
	{
	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
	return 0;

	/* Transition with new state-specific callbacks */
	switch (state) {
	case CLOCK_EVT_STATE_DETACHED:
	/* The clockevent device is getting replaced. Shut it down. */

	case CLOCK_EVT_STATE_SHUTDOWN:
	if (dev->set_state_shutdown)
	return dev->set_state_shutdown(dev);
	return 0;

	case CLOCK_EVT_STATE_PERIODIC:
	/* Core internal bug */
	if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
	return -ENOSYS;
	if (dev->set_state_periodic)
	return dev->set_state_periodic(dev);
	return 0;

	case CLOCK_EVT_STATE_ONESHOT:
	/* Core internal bug */
	if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
	return -ENOSYS;
	if (dev->set_state_oneshot)
	return dev->set_state_oneshot(dev);
	return 0;

	case CLOCK_EVT_STATE_ONESHOT_STOPPED:
	/* Core internal bug */
	if (WARN_ONCE(!clockevent_state_oneshot(dev),
	"Current state: %d\n",
	clockevent_get_state(dev)))
	return -EINVAL;

	if (dev->set_state_oneshot_stopped)
	return dev->set_state_oneshot_stopped(dev);
	else
	return -ENOSYS;

	default:
	return -ENOSYS;
	}
	}

	/**
	* clockevents_switch_state - set the operating state of a clock event device
	* @dev: device to modify
	* @state: new state
	*
	* Must be called with interrupts disabled !
	*/
	void clockevents_switch_state(struct clock_event_device *dev,
	enum clock_event_state state)
	{
	if (clockevent_get_state(dev) != state) {
	if (__clockevents_switch_state(dev, state))
	return;

	clockevent_set_state(dev, state);

	/*
	* A nsec2cyc multiplicator of 0 is invalid and we'd crash
	* on it, so fix it up and emit a warning:
	*/
	if (clockevent_state_oneshot(dev)) {
	if (unlikely(!dev->mult)) {
	dev->mult = 1;
	WARN_ON(1);
	}
	}
	}
	}

	/**
	* clockevents_shutdown - shutdown the device and clear next_event
	* @dev: device to shutdown
	*/
	void clockevents_shutdown(struct clock_event_device *dev)
	{
	clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
	dev->next_event.tv64 = KTIME_MAX;
	}

	/**
	* clockevents_tick_resume - Resume the tick device before using it again
	* @dev: device to resume
	*/
	int clockevents_tick_resume(struct clock_event_device *dev)
	{
	int ret = 0;

	if (dev->tick_resume)
	ret = dev->tick_resume(dev);

	return ret;
	}

	#ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST

	/* Limit min_delta to a jiffie */
	#define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ)

	/**
	* clockevents_increase_min_delta - raise minimum delta of a clock event device
	* @dev: device to increase the minimum delta
	*
	* Returns 0 on success, -ETIME when the minimum delta reached the limit.
	*/
	static int clockevents_increase_min_delta(struct clock_event_device *dev)
	{
	/* Nothing to do if we already reached the limit */
	if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
	printk_deferred(KERN_WARNING
	"CE: Reprogramming failure. Giving up\n");
	dev->next_event.tv64 = KTIME_MAX;
	return -ETIME;
	}

	if (dev->min_delta_ns < 5000)
	dev->min_delta_ns = 5000;
	else
	dev->min_delta_ns += dev->min_delta_ns >> 1;

	if (dev->min_delta_ns > MIN_DELTA_LIMIT)
	dev->min_delta_ns = MIN_DELTA_LIMIT;

	printk_deferred(KERN_WARNING
	"CE: %s increased min_delta_ns to %llu nsec\n",
	dev->name ? dev->name : "?",
	(unsigned long long) dev->min_delta_ns);
	return 0;
	}

	/**
	* clockevents_program_min_delta - Set clock event device to the minimum delay.
	* @dev: device to program
	*
	* Returns 0 on success, -ETIME when the retry loop failed.
	*/
	static int clockevents_program_min_delta(struct clock_event_device *dev)
	{
	unsigned long long clc;
	int64_t delta;
	int i;

	for (i = 0;;) {
	delta = dev->min_delta_ns;
	dev->next_event = ktime_add_ns(ktime_get(), delta);

	if (clockevent_state_shutdown(dev))
	return 0;

	dev->retries++;
	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
	exynos_ss_clockevent(clc, delta, &dev->next_event);
	if (dev->set_next_event((unsigned long) clc, dev) == 0)
	return 0;

	if (++i > 2) {
	/*
	* We tried 3 times to program the device with the
	* given min_delta_ns. Try to increase the minimum
	* delta, if that fails as well get out of here.
	*/
	if (clockevents_increase_min_delta(dev))
	return -ETIME;
	i = 0;
	}
	}
	}

	#else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */

	/**
	* clockevents_program_min_delta - Set clock event device to the minimum delay.
	* @dev: device to program
	*
	* Returns 0 on success, -ETIME when the retry loop failed.
	*/
	static int clockevents_program_min_delta(struct clock_event_device *dev)
	{
	unsigned long long clc;
	int64_t delta;

	delta = dev->min_delta_ns;
	dev->next_event = ktime_add_ns(ktime_get(), delta);

	if (clockevent_state_shutdown(dev))
	return 0;

	dev->retries++;
	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
	exynos_ss_clockevent(clc, delta, &dev->next_event);
	return dev->set_next_event((unsigned long) clc, dev);
	}

	#endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */

	/**
	* clockevents_program_event - Reprogram the clock event device.
	* @dev: device to program
	* @expires: absolute expiry time (monotonic clock)
	* @force: program minimum delay if expires can not be set
	*
	* Returns 0 on success, -ETIME when the event is in the past.
	*/
	int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
	bool force)
	{
	unsigned long long clc;
	int64_t delta;
	int rc;

	if (unlikely(expires.tv64 < 0)) {
	WARN_ON_ONCE(1);
	return -ETIME;
	}

	dev->next_event = expires;

	if (clockevent_state_shutdown(dev))
	return 0;

	/* We must be in ONESHOT state here */
	WARN_ONCE(!clockevent_state_oneshot(dev), "Current state: %d\n",
	clockevent_get_state(dev));

	/* Shortcut for clockevent devices that can deal with ktime. */
	if (dev->features & CLOCK_EVT_FEAT_KTIME)
	return dev->set_next_ktime(expires, dev);

	delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
	if (delta <= 0)
	return force ? clockevents_program_min_delta(dev) : -ETIME;

	delta = min(delta, (int64_t) dev->max_delta_ns);
	delta = max(delta, (int64_t) dev->min_delta_ns);

	clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
	exynos_ss_clockevent(clc, delta, &dev->next_event);
	rc = dev->set_next_event((unsigned long) clc, dev);

	return (rc && force) ? clockevents_program_min_delta(dev) : rc;
	}

	/*
	* 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);
	tick_check_new_device(dev);
	}
	}

	/*
	* Try to install a replacement clock event device
	*/
	static int clockevents_replace(struct clock_event_device *ced)
	{
	struct clock_event_device dev, newdev = NULL;

	list_for_each_entry(dev, &clockevent_devices, list) {
	if (dev == ced \|\| !clockevent_state_detached(dev))
	continue;

	if (!tick_check_replacement(newdev, dev))
	continue;

	if (!try_module_get(dev->owner))
	continue;

	if (newdev)
	module_put(newdev->owner);
	newdev = dev;
	}
	if (newdev) {
	tick_install_replacement(newdev);
	list_del_init(&ced->list);
	}
	return newdev ? 0 : -EBUSY;
	}

	/*
	* Called with clockevents_mutex and clockevents_lock held
	*/
	static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
	{
	/* Fast track. Device is unused */
	if (clockevent_state_detached(ced)) {
	list_del_init(&ced->list);
	return 0;
	}

	return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
	}

	/*
	* SMP function call to unbind a device
	*/
	static void __clockevents_unbind(void *arg)
	{
	struct ce_unbind *cu = arg;
	int res;

	raw_spin_lock(&clockevents_lock);
	res = __clockevents_try_unbind(cu->ce, smp_processor_id());
	if (res == -EAGAIN)
	res = clockevents_replace(cu->ce);
	cu->res = res;
	raw_spin_unlock(&clockevents_lock);
	}

	/*
	* Issues smp function call to unbind a per cpu device. Called with
	* clockevents_mutex held.
	*/
	static int clockevents_unbind(struct clock_event_device *ced, int cpu)
	{
	struct ce_unbind cu = { .ce = ced, .res = -ENODEV };

	smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
	return cu.res;
	}

	/*
	* Unbind a clockevents device.
	*/
	int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
	{
	int ret;

	mutex_lock(&clockevents_mutex);
	ret = clockevents_unbind(ced, cpu);
	mutex_unlock(&clockevents_mutex);
	return ret;
	}
	EXPORT_SYMBOL_GPL(clockevents_unbind_device);

	/**
	* clockevents_register_device - register a clock event device
	* @dev: device to register
	*/
	void clockevents_register_device(struct clock_event_device *dev)
	{
	unsigned long flags;

	/* Initialize state to DETACHED */
	clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);

	if (!dev->cpumask) {
	WARN_ON(num_possible_cpus() > 1);
	dev->cpumask = cpumask_of(smp_processor_id());
	}

	raw_spin_lock_irqsave(&clockevents_lock, flags);

	list_add(&dev->list, &clockevent_devices);
	tick_check_new_device(dev);
	clockevents_notify_released();

	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
	}
	EXPORT_SYMBOL_GPL(clockevents_register_device);

	void clockevents_config(struct clock_event_device *dev, u32 freq)
	{
	u64 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 = cev_delta2ns(dev->min_delta_ticks, dev, false);
	dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
	}

	/**
	* 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);
	}
	EXPORT_SYMBOL_GPL(clockevents_config_and_register);

	int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
	{
	clockevents_config(dev, freq);

	if (clockevent_state_oneshot(dev))
	return clockevents_program_event(dev, dev->next_event, false);

	if (clockevent_state_periodic(dev))
	return __clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);

	return 0;
	}

	/**
	* 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. If called for the broadcast device the core takes
	* care of serialization.
	*
	* Returns 0 on success, -ETIME when the event is in the past.
	*/
	int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
	{
	unsigned long flags;
	int ret;

	local_irq_save(flags);
	ret = tick_broadcast_update_freq(dev, freq);
	if (ret == -ENODEV)
	ret = __clockevents_update_freq(dev, freq);
	local_irq_restore(flags);
	return ret;
	}

	/*
	* 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 various tick functions with clockevents_lock held and
	* interrupts disabled.
	*/
	void clockevents_exchange_device(struct clock_event_device *old,
	struct clock_event_device *new)
	{
	/*
	* Caller releases a clock event device. We queue it into the
	* released list and do a notify add later.
	*/
	if (old) {
	module_put(old->owner);
	clockevents_switch_state(old, CLOCK_EVT_STATE_DETACHED);
	list_del(&old->list);
	list_add(&old->list, &clockevents_released);
	}

	if (new) {
	BUG_ON(!clockevent_state_detached(new));
	clockevents_shutdown(new);
	}
	}

	/**
	* clockevents_suspend - suspend clock devices
	*/
	void clockevents_suspend(void)
	{
	struct clock_event_device *dev;

	list_for_each_entry_reverse(dev, &clockevent_devices, list)
	if (dev->suspend && !clockevent_state_detached(dev))
	dev->suspend(dev);
	}

	/**
	* clockevents_resume - resume clock devices
	*/
	void clockevents_resume(void)
	{
	struct clock_event_device *dev;

	list_for_each_entry(dev, &clockevent_devices, list)
	if (dev->resume && !clockevent_state_detached(dev))
	dev->resume(dev);
	}

	#ifdef CONFIG_HOTPLUG_CPU
	/**
	* tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu
	*/
	void tick_cleanup_dead_cpu(int cpu)
	{
	struct clock_event_device dev, tmp;
	unsigned long flags;

	raw_spin_lock_irqsave(&clockevents_lock, flags);

	tick_shutdown_broadcast_oneshot(cpu);
	tick_shutdown_broadcast(cpu);
	tick_shutdown(cpu);
	/*
	* Unregister the clock event devices which were
	* released from the users in the notify chain.
	*/
	list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
	list_del(&dev->list);
	/*
	* Now check whether the CPU has left unused per cpu devices
	*/
	list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
	if (cpumask_test_cpu(cpu, dev->cpumask) &&
	cpumask_weight(dev->cpumask) == 1 &&
	!tick_is_broadcast_device(dev)) {
	BUG_ON(!clockevent_state_detached(dev));
	list_del(&dev->list);
	}
	}
	raw_spin_unlock_irqrestore(&clockevents_lock, flags);
	}
	#endif

	#ifdef CONFIG_SYSFS
	struct bus_type clockevents_subsys = {
	.name = "clockevents",
	.dev_name = "clockevent",
	};

	static DEFINE_PER_CPU(struct device, tick_percpu_dev);
	static struct tick_device tick_get_tick_dev(struct device dev);

	static ssize_t sysfs_show_current_tick_dev(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct tick_device *td;
	ssize_t count = 0;

	raw_spin_lock_irq(&clockevents_lock);
	td = tick_get_tick_dev(dev);
	if (td && td->evtdev)
	count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
	raw_spin_unlock_irq(&clockevents_lock);
	return count;
	}
	static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);

	/* We don't support the abomination of removable broadcast devices */
	static ssize_t sysfs_unbind_tick_dev(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	char name[CS_NAME_LEN];
	ssize_t ret = sysfs_get_uname(buf, name, count);
	struct clock_event_device *ce;

	if (ret < 0)
	return ret;

	ret = -ENODEV;
	mutex_lock(&clockevents_mutex);
	raw_spin_lock_irq(&clockevents_lock);
	list_for_each_entry(ce, &clockevent_devices, list) {
	if (!strcmp(ce->name, name)) {
	ret = __clockevents_try_unbind(ce, dev->id);
	break;
	}
	}
	raw_spin_unlock_irq(&clockevents_lock);
	/*
	* We hold clockevents_mutex, so ce can't go away
	*/
	if (ret == -EAGAIN)
	ret = clockevents_unbind(ce, dev->id);
	mutex_unlock(&clockevents_mutex);
	return ret ? ret : count;
	}
	static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);

	#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
	static struct device tick_bc_dev = {
	.init_name = "broadcast",
	.id = 0,
	.bus = &clockevents_subsys,
	};

	static struct tick_device tick_get_tick_dev(struct device dev)
	{
	return dev == &tick_bc_dev ? tick_get_broadcast_device() :
	&per_cpu(tick_cpu_device, dev->id);
	}

	static __init int tick_broadcast_init_sysfs(void)
	{
	int err = device_register(&tick_bc_dev);

	if (!err)
	err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
	return err;
	}
	#else
	static struct tick_device tick_get_tick_dev(struct device dev)
	{
	return &per_cpu(tick_cpu_device, dev->id);
	}
	static inline int tick_broadcast_init_sysfs(void) { return 0; }
	#endif

	static int __init tick_init_sysfs(void)
	{
	int cpu;

	for_each_possible_cpu(cpu) {
	struct device *dev = &per_cpu(tick_percpu_dev, cpu);
	int err;

	dev->id = cpu;
	dev->bus = &clockevents_subsys;
	err = device_register(dev);
	if (!err)
	err = device_create_file(dev, &dev_attr_current_device);
	if (!err)
	err = device_create_file(dev, &dev_attr_unbind_device);
	if (err)
	return err;
	}
	return tick_broadcast_init_sysfs();
	}

	static int __init clockevents_init_sysfs(void)
	{
	int err = subsys_system_register(&clockevents_subsys, NULL);

	if (!err)
	err = tick_init_sysfs();
	return err;
	}
	device_initcall(clockevents_init_sysfs);
	#endif /* SYSFS */