1d316c57fSThomas Gleixner /* 2d316c57fSThomas Gleixner * linux/kernel/time/clockevents.c 3d316c57fSThomas Gleixner * 4d316c57fSThomas Gleixner * This file contains functions which manage clock event devices. 5d316c57fSThomas Gleixner * 6d316c57fSThomas Gleixner * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> 7d316c57fSThomas Gleixner * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar 8d316c57fSThomas Gleixner * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner 9d316c57fSThomas Gleixner * 10d316c57fSThomas Gleixner * This code is licenced under the GPL version 2. For details see 11d316c57fSThomas Gleixner * kernel-base/COPYING. 12d316c57fSThomas Gleixner */ 13d316c57fSThomas Gleixner 14d316c57fSThomas Gleixner #include <linux/clockchips.h> 15d316c57fSThomas Gleixner #include <linux/hrtimer.h> 16d316c57fSThomas Gleixner #include <linux/init.h> 17d316c57fSThomas Gleixner #include <linux/module.h> 18d316c57fSThomas Gleixner #include <linux/notifier.h> 19d316c57fSThomas Gleixner #include <linux/smp.h> 20d316c57fSThomas Gleixner #include <linux/sysdev.h> 21eea08f32SArun R Bharadwaj #include <linux/tick.h> 22d316c57fSThomas Gleixner 238e1a928aSH Hartley Sweeten #include "tick-internal.h" 248e1a928aSH Hartley Sweeten 25d316c57fSThomas Gleixner /* The registered clock event devices */ 26d316c57fSThomas Gleixner static LIST_HEAD(clockevent_devices); 27d316c57fSThomas Gleixner static LIST_HEAD(clockevents_released); 28d316c57fSThomas Gleixner 29d316c57fSThomas Gleixner /* Notification for clock events */ 30d316c57fSThomas Gleixner static RAW_NOTIFIER_HEAD(clockevents_chain); 31d316c57fSThomas Gleixner 32d316c57fSThomas Gleixner /* Protection for the above */ 33b5f91da0SThomas Gleixner static DEFINE_RAW_SPINLOCK(clockevents_lock); 34d316c57fSThomas Gleixner 35d316c57fSThomas Gleixner /** 36d316c57fSThomas Gleixner * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds 37d316c57fSThomas Gleixner * @latch: value to convert 38d316c57fSThomas Gleixner * @evt: pointer to clock event device descriptor 39d316c57fSThomas Gleixner * 40d316c57fSThomas Gleixner * Math helper, returns latch value converted to nanoseconds (bound checked) 41d316c57fSThomas Gleixner */ 4297813f2fSJon Hunter u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt) 43d316c57fSThomas Gleixner { 4497813f2fSJon Hunter u64 clc = (u64) latch << evt->shift; 45d316c57fSThomas Gleixner 4645fe4fe1SIngo Molnar if (unlikely(!evt->mult)) { 4745fe4fe1SIngo Molnar evt->mult = 1; 4845fe4fe1SIngo Molnar WARN_ON(1); 4945fe4fe1SIngo Molnar } 5045fe4fe1SIngo Molnar 51d316c57fSThomas Gleixner do_div(clc, evt->mult); 52d316c57fSThomas Gleixner if (clc < 1000) 53d316c57fSThomas Gleixner clc = 1000; 5497813f2fSJon Hunter if (clc > KTIME_MAX) 5597813f2fSJon Hunter clc = KTIME_MAX; 56d316c57fSThomas Gleixner 5797813f2fSJon Hunter return clc; 58d316c57fSThomas Gleixner } 59c81fc2c3SMagnus Damm EXPORT_SYMBOL_GPL(clockevent_delta2ns); 60d316c57fSThomas Gleixner 61d316c57fSThomas Gleixner /** 62d316c57fSThomas Gleixner * clockevents_set_mode - set the operating mode of a clock event device 63d316c57fSThomas Gleixner * @dev: device to modify 64d316c57fSThomas Gleixner * @mode: new mode 65d316c57fSThomas Gleixner * 66d316c57fSThomas Gleixner * Must be called with interrupts disabled ! 67d316c57fSThomas Gleixner */ 68d316c57fSThomas Gleixner void clockevents_set_mode(struct clock_event_device *dev, 69d316c57fSThomas Gleixner enum clock_event_mode mode) 70d316c57fSThomas Gleixner { 71d316c57fSThomas Gleixner if (dev->mode != mode) { 72d316c57fSThomas Gleixner dev->set_mode(mode, dev); 73d316c57fSThomas Gleixner dev->mode = mode; 742d68259dSMagnus Damm 752d68259dSMagnus Damm /* 762d68259dSMagnus Damm * A nsec2cyc multiplicator of 0 is invalid and we'd crash 772d68259dSMagnus Damm * on it, so fix it up and emit a warning: 782d68259dSMagnus Damm */ 792d68259dSMagnus Damm if (mode == CLOCK_EVT_MODE_ONESHOT) { 802d68259dSMagnus Damm if (unlikely(!dev->mult)) { 812d68259dSMagnus Damm dev->mult = 1; 822d68259dSMagnus Damm WARN_ON(1); 832d68259dSMagnus Damm } 842d68259dSMagnus Damm } 85d316c57fSThomas Gleixner } 86d316c57fSThomas Gleixner } 87d316c57fSThomas Gleixner 88d316c57fSThomas Gleixner /** 892344abbcSThomas Gleixner * clockevents_shutdown - shutdown the device and clear next_event 902344abbcSThomas Gleixner * @dev: device to shutdown 912344abbcSThomas Gleixner */ 922344abbcSThomas Gleixner void clockevents_shutdown(struct clock_event_device *dev) 932344abbcSThomas Gleixner { 942344abbcSThomas Gleixner clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); 952344abbcSThomas Gleixner dev->next_event.tv64 = KTIME_MAX; 962344abbcSThomas Gleixner } 972344abbcSThomas Gleixner 982344abbcSThomas Gleixner /** 99d316c57fSThomas Gleixner * clockevents_program_event - Reprogram the clock event device. 100d316c57fSThomas Gleixner * @expires: absolute expiry time (monotonic clock) 101d316c57fSThomas Gleixner * 102d316c57fSThomas Gleixner * Returns 0 on success, -ETIME when the event is in the past. 103d316c57fSThomas Gleixner */ 104d316c57fSThomas Gleixner int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, 105d316c57fSThomas Gleixner ktime_t now) 106d316c57fSThomas Gleixner { 107d316c57fSThomas Gleixner unsigned long long clc; 108d316c57fSThomas Gleixner int64_t delta; 109d316c57fSThomas Gleixner 110167b1de3SThomas Gleixner if (unlikely(expires.tv64 < 0)) { 111167b1de3SThomas Gleixner WARN_ON_ONCE(1); 112167b1de3SThomas Gleixner return -ETIME; 113167b1de3SThomas Gleixner } 114167b1de3SThomas Gleixner 115d316c57fSThomas Gleixner delta = ktime_to_ns(ktime_sub(expires, now)); 116d316c57fSThomas Gleixner 117d316c57fSThomas Gleixner if (delta <= 0) 118d316c57fSThomas Gleixner return -ETIME; 119d316c57fSThomas Gleixner 120d316c57fSThomas Gleixner dev->next_event = expires; 121d316c57fSThomas Gleixner 122d316c57fSThomas Gleixner if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) 123d316c57fSThomas Gleixner return 0; 124d316c57fSThomas Gleixner 125d316c57fSThomas Gleixner if (delta > dev->max_delta_ns) 126d316c57fSThomas Gleixner delta = dev->max_delta_ns; 127d316c57fSThomas Gleixner if (delta < dev->min_delta_ns) 128d316c57fSThomas Gleixner delta = dev->min_delta_ns; 129d316c57fSThomas Gleixner 130d316c57fSThomas Gleixner clc = delta * dev->mult; 131d316c57fSThomas Gleixner clc >>= dev->shift; 132d316c57fSThomas Gleixner 133d316c57fSThomas Gleixner return dev->set_next_event((unsigned long) clc, dev); 134d316c57fSThomas Gleixner } 135d316c57fSThomas Gleixner 136d316c57fSThomas Gleixner /** 137d316c57fSThomas Gleixner * clockevents_register_notifier - register a clock events change listener 138d316c57fSThomas Gleixner */ 139d316c57fSThomas Gleixner int clockevents_register_notifier(struct notifier_block *nb) 140d316c57fSThomas Gleixner { 141f833bab8SSuresh Siddha unsigned long flags; 142d316c57fSThomas Gleixner int ret; 143d316c57fSThomas Gleixner 144b5f91da0SThomas Gleixner raw_spin_lock_irqsave(&clockevents_lock, flags); 145d316c57fSThomas Gleixner ret = raw_notifier_chain_register(&clockevents_chain, nb); 146b5f91da0SThomas Gleixner raw_spin_unlock_irqrestore(&clockevents_lock, flags); 147d316c57fSThomas Gleixner 148d316c57fSThomas Gleixner return ret; 149d316c57fSThomas Gleixner } 150d316c57fSThomas Gleixner 151d316c57fSThomas Gleixner /* 152d316c57fSThomas Gleixner * Notify about a clock event change. Called with clockevents_lock 153d316c57fSThomas Gleixner * held. 154d316c57fSThomas Gleixner */ 155d316c57fSThomas Gleixner static void clockevents_do_notify(unsigned long reason, void *dev) 156d316c57fSThomas Gleixner { 157d316c57fSThomas Gleixner raw_notifier_call_chain(&clockevents_chain, reason, dev); 158d316c57fSThomas Gleixner } 159d316c57fSThomas Gleixner 160d316c57fSThomas Gleixner /* 1613eb05676SLi Zefan * Called after a notify add to make devices available which were 162d316c57fSThomas Gleixner * released from the notifier call. 163d316c57fSThomas Gleixner */ 164d316c57fSThomas Gleixner static void clockevents_notify_released(void) 165d316c57fSThomas Gleixner { 166d316c57fSThomas Gleixner struct clock_event_device *dev; 167d316c57fSThomas Gleixner 168d316c57fSThomas Gleixner while (!list_empty(&clockevents_released)) { 169d316c57fSThomas Gleixner dev = list_entry(clockevents_released.next, 170d316c57fSThomas Gleixner struct clock_event_device, list); 171d316c57fSThomas Gleixner list_del(&dev->list); 172d316c57fSThomas Gleixner list_add(&dev->list, &clockevent_devices); 173d316c57fSThomas Gleixner clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); 174d316c57fSThomas Gleixner } 175d316c57fSThomas Gleixner } 176d316c57fSThomas Gleixner 177d316c57fSThomas Gleixner /** 178d316c57fSThomas Gleixner * clockevents_register_device - register a clock event device 179d316c57fSThomas Gleixner * @dev: device to register 180d316c57fSThomas Gleixner */ 181d316c57fSThomas Gleixner void clockevents_register_device(struct clock_event_device *dev) 182d316c57fSThomas Gleixner { 183f833bab8SSuresh Siddha unsigned long flags; 184f833bab8SSuresh Siddha 185d316c57fSThomas Gleixner BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); 186320ab2b0SRusty Russell BUG_ON(!dev->cpumask); 187320ab2b0SRusty Russell 188b5f91da0SThomas Gleixner raw_spin_lock_irqsave(&clockevents_lock, flags); 189d316c57fSThomas Gleixner 190d316c57fSThomas Gleixner list_add(&dev->list, &clockevent_devices); 191d316c57fSThomas Gleixner clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); 192d316c57fSThomas Gleixner clockevents_notify_released(); 193d316c57fSThomas Gleixner 194b5f91da0SThomas Gleixner raw_spin_unlock_irqrestore(&clockevents_lock, flags); 195d316c57fSThomas Gleixner } 196c81fc2c3SMagnus Damm EXPORT_SYMBOL_GPL(clockevents_register_device); 197d316c57fSThomas Gleixner 198d316c57fSThomas Gleixner /* 199d316c57fSThomas Gleixner * Noop handler when we shut down an event device 200d316c57fSThomas Gleixner */ 2017c1e7689SVenkatesh Pallipadi void clockevents_handle_noop(struct clock_event_device *dev) 202d316c57fSThomas Gleixner { 203d316c57fSThomas Gleixner } 204d316c57fSThomas Gleixner 205d316c57fSThomas Gleixner /** 206d316c57fSThomas Gleixner * clockevents_exchange_device - release and request clock devices 207d316c57fSThomas Gleixner * @old: device to release (can be NULL) 208d316c57fSThomas Gleixner * @new: device to request (can be NULL) 209d316c57fSThomas Gleixner * 210d316c57fSThomas Gleixner * Called from the notifier chain. clockevents_lock is held already 211d316c57fSThomas Gleixner */ 212d316c57fSThomas Gleixner void clockevents_exchange_device(struct clock_event_device *old, 213d316c57fSThomas Gleixner struct clock_event_device *new) 214d316c57fSThomas Gleixner { 215d316c57fSThomas Gleixner unsigned long flags; 216d316c57fSThomas Gleixner 217d316c57fSThomas Gleixner local_irq_save(flags); 218d316c57fSThomas Gleixner /* 219d316c57fSThomas Gleixner * Caller releases a clock event device. We queue it into the 220d316c57fSThomas Gleixner * released list and do a notify add later. 221d316c57fSThomas Gleixner */ 222d316c57fSThomas Gleixner if (old) { 223d316c57fSThomas Gleixner clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); 224d316c57fSThomas Gleixner list_del(&old->list); 225d316c57fSThomas Gleixner list_add(&old->list, &clockevents_released); 226d316c57fSThomas Gleixner } 227d316c57fSThomas Gleixner 228d316c57fSThomas Gleixner if (new) { 229d316c57fSThomas Gleixner BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); 2302344abbcSThomas Gleixner clockevents_shutdown(new); 231d316c57fSThomas Gleixner } 232d316c57fSThomas Gleixner local_irq_restore(flags); 233d316c57fSThomas Gleixner } 234d316c57fSThomas Gleixner 235de68d9b1SThomas Gleixner #ifdef CONFIG_GENERIC_CLOCKEVENTS 236d316c57fSThomas Gleixner /** 237d316c57fSThomas Gleixner * clockevents_notify - notification about relevant events 238d316c57fSThomas Gleixner */ 239d316c57fSThomas Gleixner void clockevents_notify(unsigned long reason, void *arg) 240d316c57fSThomas Gleixner { 241bb6eddf7SThomas Gleixner struct clock_event_device *dev, *tmp; 242f833bab8SSuresh Siddha unsigned long flags; 243bb6eddf7SThomas Gleixner int cpu; 2440b858e6fSLi Zefan 245b5f91da0SThomas Gleixner raw_spin_lock_irqsave(&clockevents_lock, flags); 246d316c57fSThomas Gleixner clockevents_do_notify(reason, arg); 247d316c57fSThomas Gleixner 248d316c57fSThomas Gleixner switch (reason) { 249d316c57fSThomas Gleixner case CLOCK_EVT_NOTIFY_CPU_DEAD: 250d316c57fSThomas Gleixner /* 251d316c57fSThomas Gleixner * Unregister the clock event devices which were 252d316c57fSThomas Gleixner * released from the users in the notify chain. 253d316c57fSThomas Gleixner */ 254bb6eddf7SThomas Gleixner list_for_each_entry_safe(dev, tmp, &clockevents_released, list) 255bb6eddf7SThomas Gleixner list_del(&dev->list); 256bb6eddf7SThomas Gleixner /* 257bb6eddf7SThomas Gleixner * Now check whether the CPU has left unused per cpu devices 258bb6eddf7SThomas Gleixner */ 259bb6eddf7SThomas Gleixner cpu = *((int *)arg); 260bb6eddf7SThomas Gleixner list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) { 261bb6eddf7SThomas Gleixner if (cpumask_test_cpu(cpu, dev->cpumask) && 262ea9d8e3fSXiaotian Feng cpumask_weight(dev->cpumask) == 1 && 263ea9d8e3fSXiaotian Feng !tick_is_broadcast_device(dev)) { 264bb6eddf7SThomas Gleixner BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); 265bb6eddf7SThomas Gleixner list_del(&dev->list); 266bb6eddf7SThomas Gleixner } 267bb6eddf7SThomas Gleixner } 268d316c57fSThomas Gleixner break; 269d316c57fSThomas Gleixner default: 270d316c57fSThomas Gleixner break; 271d316c57fSThomas Gleixner } 272b5f91da0SThomas Gleixner raw_spin_unlock_irqrestore(&clockevents_lock, flags); 273d316c57fSThomas Gleixner } 274d316c57fSThomas Gleixner EXPORT_SYMBOL_GPL(clockevents_notify); 275de68d9b1SThomas Gleixner #endif 276