Fix gcc 4.5.1 miscompiling drivers/char/i8k.c (again)
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / time / clockevents.c
blobd7395fdfb9f38f931761e29d14534143dbe3799c
1 /*
2 * linux/kernel/time/clockevents.c
4 * This file contains functions which manage clock event devices.
6 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
8 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
10 * This code is licenced under the GPL version 2. For details see
11 * kernel-base/COPYING.
14 #include <linux/clockchips.h>
15 #include <linux/hrtimer.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/notifier.h>
19 #include <linux/smp.h>
20 #include <linux/sysdev.h>
21 #include <linux/tick.h>
23 #include "tick-internal.h"
25 /* The registered clock event devices */
26 static LIST_HEAD(clockevent_devices);
27 static LIST_HEAD(clockevents_released);
29 /* Notification for clock events */
30 static RAW_NOTIFIER_HEAD(clockevents_chain);
32 /* Protection for the above */
33 static DEFINE_RAW_SPINLOCK(clockevents_lock);
35 /**
36 * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
37 * @latch: value to convert
38 * @evt: pointer to clock event device descriptor
40 * Math helper, returns latch value converted to nanoseconds (bound checked)
42 u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
44 u64 clc = (u64) latch << evt->shift;
46 if (unlikely(!evt->mult)) {
47 evt->mult = 1;
48 WARN_ON(1);
51 do_div(clc, evt->mult);
52 if (clc < 1000)
53 clc = 1000;
54 if (clc > KTIME_MAX)
55 clc = KTIME_MAX;
57 return clc;
59 EXPORT_SYMBOL_GPL(clockevent_delta2ns);
61 /**
62 * clockevents_set_mode - set the operating mode of a clock event device
63 * @dev: device to modify
64 * @mode: new mode
66 * Must be called with interrupts disabled !
68 void clockevents_set_mode(struct clock_event_device *dev,
69 enum clock_event_mode mode)
71 if (dev->mode != mode) {
72 dev->set_mode(mode, dev);
73 dev->mode = mode;
76 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
77 * on it, so fix it up and emit a warning:
79 if (mode == CLOCK_EVT_MODE_ONESHOT) {
80 if (unlikely(!dev->mult)) {
81 dev->mult = 1;
82 WARN_ON(1);
88 /**
89 * clockevents_shutdown - shutdown the device and clear next_event
90 * @dev: device to shutdown
92 void clockevents_shutdown(struct clock_event_device *dev)
94 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
95 dev->next_event.tv64 = KTIME_MAX;
98 /**
99 * clockevents_program_event - Reprogram the clock event device.
100 * @expires: absolute expiry time (monotonic clock)
102 * Returns 0 on success, -ETIME when the event is in the past.
104 int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
105 ktime_t now)
107 unsigned long long clc;
108 int64_t delta;
110 if (unlikely(expires.tv64 < 0)) {
111 WARN_ON_ONCE(1);
112 return -ETIME;
115 delta = ktime_to_ns(ktime_sub(expires, now));
117 if (delta <= 0)
118 return -ETIME;
120 dev->next_event = expires;
122 if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
123 return 0;
125 if (delta > dev->max_delta_ns)
126 delta = dev->max_delta_ns;
127 if (delta < dev->min_delta_ns)
128 delta = dev->min_delta_ns;
130 clc = delta * dev->mult;
131 clc >>= dev->shift;
133 return dev->set_next_event((unsigned long) clc, dev);
137 * clockevents_register_notifier - register a clock events change listener
139 int clockevents_register_notifier(struct notifier_block *nb)
141 unsigned long flags;
142 int ret;
144 raw_spin_lock_irqsave(&clockevents_lock, flags);
145 ret = raw_notifier_chain_register(&clockevents_chain, nb);
146 raw_spin_unlock_irqrestore(&clockevents_lock, flags);
148 return ret;
152 * Notify about a clock event change. Called with clockevents_lock
153 * held.
155 static void clockevents_do_notify(unsigned long reason, void *dev)
157 raw_notifier_call_chain(&clockevents_chain, reason, dev);
161 * Called after a notify add to make devices available which were
162 * released from the notifier call.
164 static void clockevents_notify_released(void)
166 struct clock_event_device *dev;
168 while (!list_empty(&clockevents_released)) {
169 dev = list_entry(clockevents_released.next,
170 struct clock_event_device, list);
171 list_del(&dev->list);
172 list_add(&dev->list, &clockevent_devices);
173 clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
178 * clockevents_register_device - register a clock event device
179 * @dev: device to register
181 void clockevents_register_device(struct clock_event_device *dev)
183 unsigned long flags;
185 BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
186 BUG_ON(!dev->cpumask);
188 raw_spin_lock_irqsave(&clockevents_lock, flags);
190 list_add(&dev->list, &clockevent_devices);
191 clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
192 clockevents_notify_released();
194 raw_spin_unlock_irqrestore(&clockevents_lock, flags);
196 EXPORT_SYMBOL_GPL(clockevents_register_device);
199 * Noop handler when we shut down an event device
201 void clockevents_handle_noop(struct clock_event_device *dev)
206 * clockevents_exchange_device - release and request clock devices
207 * @old: device to release (can be NULL)
208 * @new: device to request (can be NULL)
210 * Called from the notifier chain. clockevents_lock is held already
212 void clockevents_exchange_device(struct clock_event_device *old,
213 struct clock_event_device *new)
215 unsigned long flags;
217 local_irq_save(flags);
219 * Caller releases a clock event device. We queue it into the
220 * released list and do a notify add later.
222 if (old) {
223 clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
224 list_del(&old->list);
225 list_add(&old->list, &clockevents_released);
228 if (new) {
229 BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
230 clockevents_shutdown(new);
232 local_irq_restore(flags);
235 #ifdef CONFIG_GENERIC_CLOCKEVENTS
237 * clockevents_notify - notification about relevant events
239 void clockevents_notify(unsigned long reason, void *arg)
241 struct clock_event_device *dev, *tmp;
242 unsigned long flags;
243 int cpu;
245 raw_spin_lock_irqsave(&clockevents_lock, flags);
246 clockevents_do_notify(reason, arg);
248 switch (reason) {
249 case CLOCK_EVT_NOTIFY_CPU_DEAD:
251 * Unregister the clock event devices which were
252 * released from the users in the notify chain.
254 list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
255 list_del(&dev->list);
257 * Now check whether the CPU has left unused per cpu devices
259 cpu = *((int *)arg);
260 list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
261 if (cpumask_test_cpu(cpu, dev->cpumask) &&
262 cpumask_weight(dev->cpumask) == 1 &&
263 !tick_is_broadcast_device(dev)) {
264 BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
265 list_del(&dev->list);
268 break;
269 default:
270 break;
272 raw_spin_unlock_irqrestore(&clockevents_lock, flags);
274 EXPORT_SYMBOL_GPL(clockevents_notify);
275 #endif