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 23d316c57fSThomas Gleixner /* The registered clock event devices */ 24d316c57fSThomas Gleixner static LIST_HEAD(clockevent_devices); 25d316c57fSThomas Gleixner static LIST_HEAD(clockevents_released); 26d316c57fSThomas Gleixner 27d316c57fSThomas Gleixner /* Notification for clock events */ 28d316c57fSThomas Gleixner static RAW_NOTIFIER_HEAD(clockevents_chain); 29d316c57fSThomas Gleixner 30d316c57fSThomas Gleixner /* Protection for the above */ 31d316c57fSThomas Gleixner static DEFINE_SPINLOCK(clockevents_lock); 32d316c57fSThomas Gleixner 33d316c57fSThomas Gleixner /** 34d316c57fSThomas Gleixner * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds 35d316c57fSThomas Gleixner * @latch: value to convert 36d316c57fSThomas Gleixner * @evt: pointer to clock event device descriptor 37d316c57fSThomas Gleixner * 38d316c57fSThomas Gleixner * Math helper, returns latch value converted to nanoseconds (bound checked) 39d316c57fSThomas Gleixner */ 40d316c57fSThomas Gleixner unsigned long clockevent_delta2ns(unsigned long latch, 41d316c57fSThomas Gleixner struct clock_event_device *evt) 42d316c57fSThomas Gleixner { 43d316c57fSThomas Gleixner u64 clc = ((u64) latch << evt->shift); 44d316c57fSThomas Gleixner 4545fe4fe1SIngo Molnar if (unlikely(!evt->mult)) { 4645fe4fe1SIngo Molnar evt->mult = 1; 4745fe4fe1SIngo Molnar WARN_ON(1); 4845fe4fe1SIngo Molnar } 4945fe4fe1SIngo Molnar 50d316c57fSThomas Gleixner do_div(clc, evt->mult); 51d316c57fSThomas Gleixner if (clc < 1000) 52d316c57fSThomas Gleixner clc = 1000; 53d316c57fSThomas Gleixner if (clc > LONG_MAX) 54d316c57fSThomas Gleixner clc = LONG_MAX; 55d316c57fSThomas Gleixner 56d316c57fSThomas Gleixner return (unsigned long) clc; 57d316c57fSThomas Gleixner } 58c81fc2c3SMagnus Damm EXPORT_SYMBOL_GPL(clockevent_delta2ns); 59d316c57fSThomas Gleixner 60d316c57fSThomas Gleixner /** 61d316c57fSThomas Gleixner * clockevents_set_mode - set the operating mode of a clock event device 62d316c57fSThomas Gleixner * @dev: device to modify 63d316c57fSThomas Gleixner * @mode: new mode 64d316c57fSThomas Gleixner * 65d316c57fSThomas Gleixner * Must be called with interrupts disabled ! 66d316c57fSThomas Gleixner */ 67d316c57fSThomas Gleixner void clockevents_set_mode(struct clock_event_device *dev, 68d316c57fSThomas Gleixner enum clock_event_mode mode) 69d316c57fSThomas Gleixner { 70d316c57fSThomas Gleixner if (dev->mode != mode) { 71d316c57fSThomas Gleixner dev->set_mode(mode, dev); 72d316c57fSThomas Gleixner dev->mode = mode; 732d68259dSMagnus Damm 742d68259dSMagnus Damm /* 752d68259dSMagnus Damm * A nsec2cyc multiplicator of 0 is invalid and we'd crash 762d68259dSMagnus Damm * on it, so fix it up and emit a warning: 772d68259dSMagnus Damm */ 782d68259dSMagnus Damm if (mode == CLOCK_EVT_MODE_ONESHOT) { 792d68259dSMagnus Damm if (unlikely(!dev->mult)) { 802d68259dSMagnus Damm dev->mult = 1; 812d68259dSMagnus Damm WARN_ON(1); 822d68259dSMagnus Damm } 832d68259dSMagnus Damm } 84d316c57fSThomas Gleixner } 85d316c57fSThomas Gleixner } 86d316c57fSThomas Gleixner 87d316c57fSThomas Gleixner /** 882344abbcSThomas Gleixner * clockevents_shutdown - shutdown the device and clear next_event 892344abbcSThomas Gleixner * @dev: device to shutdown 902344abbcSThomas Gleixner */ 912344abbcSThomas Gleixner void clockevents_shutdown(struct clock_event_device *dev) 922344abbcSThomas Gleixner { 932344abbcSThomas Gleixner clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); 942344abbcSThomas Gleixner dev->next_event.tv64 = KTIME_MAX; 952344abbcSThomas Gleixner } 962344abbcSThomas Gleixner 972344abbcSThomas Gleixner /** 98d316c57fSThomas Gleixner * clockevents_program_event - Reprogram the clock event device. 99d316c57fSThomas Gleixner * @expires: absolute expiry time (monotonic clock) 100d316c57fSThomas Gleixner * 101d316c57fSThomas Gleixner * Returns 0 on success, -ETIME when the event is in the past. 102d316c57fSThomas Gleixner */ 103d316c57fSThomas Gleixner int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, 104d316c57fSThomas Gleixner ktime_t now) 105d316c57fSThomas Gleixner { 106d316c57fSThomas Gleixner unsigned long long clc; 107d316c57fSThomas Gleixner int64_t delta; 108d316c57fSThomas Gleixner 109167b1de3SThomas Gleixner if (unlikely(expires.tv64 < 0)) { 110167b1de3SThomas Gleixner WARN_ON_ONCE(1); 111167b1de3SThomas Gleixner return -ETIME; 112167b1de3SThomas Gleixner } 113167b1de3SThomas Gleixner 114d316c57fSThomas Gleixner delta = ktime_to_ns(ktime_sub(expires, now)); 115d316c57fSThomas Gleixner 116d316c57fSThomas Gleixner if (delta <= 0) 117d316c57fSThomas Gleixner return -ETIME; 118d316c57fSThomas Gleixner 119d316c57fSThomas Gleixner dev->next_event = expires; 120d316c57fSThomas Gleixner 121d316c57fSThomas Gleixner if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) 122d316c57fSThomas Gleixner return 0; 123d316c57fSThomas Gleixner 124d316c57fSThomas Gleixner if (delta > dev->max_delta_ns) 125d316c57fSThomas Gleixner delta = dev->max_delta_ns; 126d316c57fSThomas Gleixner if (delta < dev->min_delta_ns) 127d316c57fSThomas Gleixner delta = dev->min_delta_ns; 128d316c57fSThomas Gleixner 129d316c57fSThomas Gleixner clc = delta * dev->mult; 130d316c57fSThomas Gleixner clc >>= dev->shift; 131d316c57fSThomas Gleixner 132d316c57fSThomas Gleixner return dev->set_next_event((unsigned long) clc, dev); 133d316c57fSThomas Gleixner } 134d316c57fSThomas Gleixner 135d316c57fSThomas Gleixner /** 136d316c57fSThomas Gleixner * clockevents_register_notifier - register a clock events change listener 137d316c57fSThomas Gleixner */ 138d316c57fSThomas Gleixner int clockevents_register_notifier(struct notifier_block *nb) 139d316c57fSThomas Gleixner { 140f833bab8SSuresh Siddha unsigned long flags; 141d316c57fSThomas Gleixner int ret; 142d316c57fSThomas Gleixner 143f833bab8SSuresh Siddha spin_lock_irqsave(&clockevents_lock, flags); 144d316c57fSThomas Gleixner ret = raw_notifier_chain_register(&clockevents_chain, nb); 145f833bab8SSuresh Siddha spin_unlock_irqrestore(&clockevents_lock, flags); 146d316c57fSThomas Gleixner 147d316c57fSThomas Gleixner return ret; 148d316c57fSThomas Gleixner } 149d316c57fSThomas Gleixner 150d316c57fSThomas Gleixner /* 151d316c57fSThomas Gleixner * Notify about a clock event change. Called with clockevents_lock 152d316c57fSThomas Gleixner * held. 153d316c57fSThomas Gleixner */ 154d316c57fSThomas Gleixner static void clockevents_do_notify(unsigned long reason, void *dev) 155d316c57fSThomas Gleixner { 156d316c57fSThomas Gleixner raw_notifier_call_chain(&clockevents_chain, reason, dev); 157d316c57fSThomas Gleixner } 158d316c57fSThomas Gleixner 159d316c57fSThomas Gleixner /* 1603eb05676SLi Zefan * Called after a notify add to make devices available which were 161d316c57fSThomas Gleixner * released from the notifier call. 162d316c57fSThomas Gleixner */ 163d316c57fSThomas Gleixner static void clockevents_notify_released(void) 164d316c57fSThomas Gleixner { 165d316c57fSThomas Gleixner struct clock_event_device *dev; 166d316c57fSThomas Gleixner 167d316c57fSThomas Gleixner while (!list_empty(&clockevents_released)) { 168d316c57fSThomas Gleixner dev = list_entry(clockevents_released.next, 169d316c57fSThomas Gleixner struct clock_event_device, list); 170d316c57fSThomas Gleixner list_del(&dev->list); 171d316c57fSThomas Gleixner list_add(&dev->list, &clockevent_devices); 172d316c57fSThomas Gleixner clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); 173d316c57fSThomas Gleixner } 174d316c57fSThomas Gleixner } 175d316c57fSThomas Gleixner 176d316c57fSThomas Gleixner /** 177d316c57fSThomas Gleixner * clockevents_register_device - register a clock event device 178d316c57fSThomas Gleixner * @dev: device to register 179d316c57fSThomas Gleixner */ 180d316c57fSThomas Gleixner void clockevents_register_device(struct clock_event_device *dev) 181d316c57fSThomas Gleixner { 182f833bab8SSuresh Siddha unsigned long flags; 183f833bab8SSuresh Siddha 184d316c57fSThomas Gleixner BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); 185320ab2b0SRusty Russell BUG_ON(!dev->cpumask); 186320ab2b0SRusty Russell 187f833bab8SSuresh Siddha spin_lock_irqsave(&clockevents_lock, flags); 188d316c57fSThomas Gleixner 189d316c57fSThomas Gleixner list_add(&dev->list, &clockevent_devices); 190d316c57fSThomas Gleixner clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); 191d316c57fSThomas Gleixner clockevents_notify_released(); 192d316c57fSThomas Gleixner 193f833bab8SSuresh Siddha spin_unlock_irqrestore(&clockevents_lock, flags); 194d316c57fSThomas Gleixner } 195c81fc2c3SMagnus Damm EXPORT_SYMBOL_GPL(clockevents_register_device); 196d316c57fSThomas Gleixner 197d316c57fSThomas Gleixner /* 198d316c57fSThomas Gleixner * Noop handler when we shut down an event device 199d316c57fSThomas Gleixner */ 2007c1e7689SVenkatesh Pallipadi void clockevents_handle_noop(struct clock_event_device *dev) 201d316c57fSThomas Gleixner { 202d316c57fSThomas Gleixner } 203d316c57fSThomas Gleixner 204d316c57fSThomas Gleixner /** 205d316c57fSThomas Gleixner * clockevents_exchange_device - release and request clock devices 206d316c57fSThomas Gleixner * @old: device to release (can be NULL) 207d316c57fSThomas Gleixner * @new: device to request (can be NULL) 208d316c57fSThomas Gleixner * 209d316c57fSThomas Gleixner * Called from the notifier chain. clockevents_lock is held already 210d316c57fSThomas Gleixner */ 211d316c57fSThomas Gleixner void clockevents_exchange_device(struct clock_event_device *old, 212d316c57fSThomas Gleixner struct clock_event_device *new) 213d316c57fSThomas Gleixner { 214d316c57fSThomas Gleixner unsigned long flags; 215d316c57fSThomas Gleixner 216d316c57fSThomas Gleixner local_irq_save(flags); 217d316c57fSThomas Gleixner /* 218d316c57fSThomas Gleixner * Caller releases a clock event device. We queue it into the 219d316c57fSThomas Gleixner * released list and do a notify add later. 220d316c57fSThomas Gleixner */ 221d316c57fSThomas Gleixner if (old) { 222d316c57fSThomas Gleixner clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); 223d316c57fSThomas Gleixner list_del(&old->list); 224d316c57fSThomas Gleixner list_add(&old->list, &clockevents_released); 225d316c57fSThomas Gleixner } 226d316c57fSThomas Gleixner 227d316c57fSThomas Gleixner if (new) { 228d316c57fSThomas Gleixner BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); 2292344abbcSThomas Gleixner clockevents_shutdown(new); 230d316c57fSThomas Gleixner } 231d316c57fSThomas Gleixner local_irq_restore(flags); 232d316c57fSThomas Gleixner } 233d316c57fSThomas Gleixner 234de68d9b1SThomas Gleixner #ifdef CONFIG_GENERIC_CLOCKEVENTS 235d316c57fSThomas Gleixner /** 236d316c57fSThomas Gleixner * clockevents_notify - notification about relevant events 237d316c57fSThomas Gleixner */ 238d316c57fSThomas Gleixner void clockevents_notify(unsigned long reason, void *arg) 239d316c57fSThomas Gleixner { 2400b858e6fSLi Zefan struct list_head *node, *tmp; 241f833bab8SSuresh Siddha unsigned long flags; 2420b858e6fSLi Zefan 243f833bab8SSuresh Siddha spin_lock_irqsave(&clockevents_lock, flags); 244d316c57fSThomas Gleixner clockevents_do_notify(reason, arg); 245d316c57fSThomas Gleixner 246d316c57fSThomas Gleixner switch (reason) { 247d316c57fSThomas Gleixner case CLOCK_EVT_NOTIFY_CPU_DEAD: 248d316c57fSThomas Gleixner /* 249d316c57fSThomas Gleixner * Unregister the clock event devices which were 250d316c57fSThomas Gleixner * released from the users in the notify chain. 251d316c57fSThomas Gleixner */ 2520b858e6fSLi Zefan list_for_each_safe(node, tmp, &clockevents_released) 2530b858e6fSLi Zefan list_del(node); 254d316c57fSThomas Gleixner break; 255d316c57fSThomas Gleixner default: 256d316c57fSThomas Gleixner break; 257d316c57fSThomas Gleixner } 258f833bab8SSuresh Siddha spin_unlock_irqrestore(&clockevents_lock, flags); 259d316c57fSThomas Gleixner } 260d316c57fSThomas Gleixner EXPORT_SYMBOL_GPL(clockevents_notify); 261de68d9b1SThomas Gleixner #endif 262