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d316c57f TG |
1 | /* |
2 | * linux/kernel/time/clockevents.c | |
3 | * | |
4 | * This file contains functions which manage clock event devices. | |
5 | * | |
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 | |
9 | * | |
10 | * This code is licenced under the GPL version 2. For details see | |
11 | * kernel-base/COPYING. | |
12 | */ | |
13 | ||
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 | ||
8e1a928a HS |
22 | #include "tick-internal.h" |
23 | ||
d316c57f TG |
24 | /* The registered clock event devices */ |
25 | static LIST_HEAD(clockevent_devices); | |
26 | static LIST_HEAD(clockevents_released); | |
27 | ||
28 | /* Notification for clock events */ | |
29 | static RAW_NOTIFIER_HEAD(clockevents_chain); | |
30 | ||
31 | /* Protection for the above */ | |
b5f91da0 | 32 | static DEFINE_RAW_SPINLOCK(clockevents_lock); |
d316c57f TG |
33 | |
34 | /** | |
35 | * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds | |
36 | * @latch: value to convert | |
37 | * @evt: pointer to clock event device descriptor | |
38 | * | |
39 | * Math helper, returns latch value converted to nanoseconds (bound checked) | |
40 | */ | |
97813f2f | 41 | u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt) |
d316c57f | 42 | { |
97813f2f | 43 | u64 clc = (u64) latch << evt->shift; |
d316c57f | 44 | |
45fe4fe1 IM |
45 | if (unlikely(!evt->mult)) { |
46 | evt->mult = 1; | |
47 | WARN_ON(1); | |
48 | } | |
49 | ||
d316c57f TG |
50 | do_div(clc, evt->mult); |
51 | if (clc < 1000) | |
52 | clc = 1000; | |
97813f2f JH |
53 | if (clc > KTIME_MAX) |
54 | clc = KTIME_MAX; | |
d316c57f | 55 | |
97813f2f | 56 | return clc; |
d316c57f | 57 | } |
c81fc2c3 | 58 | EXPORT_SYMBOL_GPL(clockevent_delta2ns); |
d316c57f TG |
59 | |
60 | /** | |
61 | * clockevents_set_mode - set the operating mode of a clock event device | |
62 | * @dev: device to modify | |
63 | * @mode: new mode | |
64 | * | |
65 | * Must be called with interrupts disabled ! | |
66 | */ | |
67 | void clockevents_set_mode(struct clock_event_device *dev, | |
68 | enum clock_event_mode mode) | |
69 | { | |
70 | if (dev->mode != mode) { | |
71 | dev->set_mode(mode, dev); | |
72 | dev->mode = mode; | |
2d68259d MD |
73 | |
74 | /* | |
75 | * A nsec2cyc multiplicator of 0 is invalid and we'd crash | |
76 | * on it, so fix it up and emit a warning: | |
77 | */ | |
78 | if (mode == CLOCK_EVT_MODE_ONESHOT) { | |
79 | if (unlikely(!dev->mult)) { | |
80 | dev->mult = 1; | |
81 | WARN_ON(1); | |
82 | } | |
83 | } | |
d316c57f TG |
84 | } |
85 | } | |
86 | ||
2344abbc TG |
87 | /** |
88 | * clockevents_shutdown - shutdown the device and clear next_event | |
89 | * @dev: device to shutdown | |
90 | */ | |
91 | void clockevents_shutdown(struct clock_event_device *dev) | |
92 | { | |
93 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); | |
94 | dev->next_event.tv64 = KTIME_MAX; | |
95 | } | |
96 | ||
d316c57f TG |
97 | /** |
98 | * clockevents_program_event - Reprogram the clock event device. | |
99 | * @expires: absolute expiry time (monotonic clock) | |
100 | * | |
101 | * Returns 0 on success, -ETIME when the event is in the past. | |
102 | */ | |
103 | int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, | |
104 | ktime_t now) | |
105 | { | |
106 | unsigned long long clc; | |
107 | int64_t delta; | |
108 | ||
167b1de3 TG |
109 | if (unlikely(expires.tv64 < 0)) { |
110 | WARN_ON_ONCE(1); | |
111 | return -ETIME; | |
112 | } | |
113 | ||
d316c57f TG |
114 | delta = ktime_to_ns(ktime_sub(expires, now)); |
115 | ||
116 | if (delta <= 0) | |
117 | return -ETIME; | |
118 | ||
119 | dev->next_event = expires; | |
120 | ||
121 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
122 | return 0; | |
123 | ||
124 | if (delta > dev->max_delta_ns) | |
125 | delta = dev->max_delta_ns; | |
126 | if (delta < dev->min_delta_ns) | |
127 | delta = dev->min_delta_ns; | |
128 | ||
129 | clc = delta * dev->mult; | |
130 | clc >>= dev->shift; | |
131 | ||
132 | return dev->set_next_event((unsigned long) clc, dev); | |
133 | } | |
134 | ||
135 | /** | |
136 | * clockevents_register_notifier - register a clock events change listener | |
137 | */ | |
138 | int clockevents_register_notifier(struct notifier_block *nb) | |
139 | { | |
f833bab8 | 140 | unsigned long flags; |
d316c57f TG |
141 | int ret; |
142 | ||
b5f91da0 | 143 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f | 144 | ret = raw_notifier_chain_register(&clockevents_chain, nb); |
b5f91da0 | 145 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f TG |
146 | |
147 | return ret; | |
148 | } | |
149 | ||
d316c57f TG |
150 | /* |
151 | * Notify about a clock event change. Called with clockevents_lock | |
152 | * held. | |
153 | */ | |
154 | static void clockevents_do_notify(unsigned long reason, void *dev) | |
155 | { | |
156 | raw_notifier_call_chain(&clockevents_chain, reason, dev); | |
157 | } | |
158 | ||
159 | /* | |
3eb05676 | 160 | * Called after a notify add to make devices available which were |
d316c57f TG |
161 | * released from the notifier call. |
162 | */ | |
163 | static void clockevents_notify_released(void) | |
164 | { | |
165 | struct clock_event_device *dev; | |
166 | ||
167 | while (!list_empty(&clockevents_released)) { | |
168 | dev = list_entry(clockevents_released.next, | |
169 | struct clock_event_device, list); | |
170 | list_del(&dev->list); | |
171 | list_add(&dev->list, &clockevent_devices); | |
172 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
173 | } | |
174 | } | |
175 | ||
176 | /** | |
177 | * clockevents_register_device - register a clock event device | |
178 | * @dev: device to register | |
179 | */ | |
180 | void clockevents_register_device(struct clock_event_device *dev) | |
181 | { | |
f833bab8 SS |
182 | unsigned long flags; |
183 | ||
d316c57f | 184 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); |
320ab2b0 RR |
185 | BUG_ON(!dev->cpumask); |
186 | ||
b5f91da0 | 187 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f TG |
188 | |
189 | list_add(&dev->list, &clockevent_devices); | |
190 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
191 | clockevents_notify_released(); | |
192 | ||
b5f91da0 | 193 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f | 194 | } |
c81fc2c3 | 195 | EXPORT_SYMBOL_GPL(clockevents_register_device); |
d316c57f | 196 | |
57f0fcbe TG |
197 | static void clockevents_config(struct clock_event_device *dev, |
198 | u32 freq) | |
199 | { | |
c0e299b1 | 200 | u64 sec; |
57f0fcbe TG |
201 | |
202 | if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
203 | return; | |
204 | ||
205 | /* | |
206 | * Calculate the maximum number of seconds we can sleep. Limit | |
207 | * to 10 minutes for hardware which can program more than | |
208 | * 32bit ticks so we still get reasonable conversion values. | |
209 | */ | |
210 | sec = dev->max_delta_ticks; | |
211 | do_div(sec, freq); | |
212 | if (!sec) | |
213 | sec = 1; | |
214 | else if (sec > 600 && dev->max_delta_ticks > UINT_MAX) | |
215 | sec = 600; | |
216 | ||
217 | clockevents_calc_mult_shift(dev, freq, sec); | |
218 | dev->min_delta_ns = clockevent_delta2ns(dev->min_delta_ticks, dev); | |
219 | dev->max_delta_ns = clockevent_delta2ns(dev->max_delta_ticks, dev); | |
220 | } | |
221 | ||
222 | /** | |
223 | * clockevents_config_and_register - Configure and register a clock event device | |
224 | * @dev: device to register | |
225 | * @freq: The clock frequency | |
226 | * @min_delta: The minimum clock ticks to program in oneshot mode | |
227 | * @max_delta: The maximum clock ticks to program in oneshot mode | |
228 | * | |
229 | * min/max_delta can be 0 for devices which do not support oneshot mode. | |
230 | */ | |
231 | void clockevents_config_and_register(struct clock_event_device *dev, | |
232 | u32 freq, unsigned long min_delta, | |
233 | unsigned long max_delta) | |
234 | { | |
235 | dev->min_delta_ticks = min_delta; | |
236 | dev->max_delta_ticks = max_delta; | |
237 | clockevents_config(dev, freq); | |
238 | clockevents_register_device(dev); | |
239 | } | |
240 | ||
80b816b7 TG |
241 | /** |
242 | * clockevents_update_freq - Update frequency and reprogram a clock event device. | |
243 | * @dev: device to modify | |
244 | * @freq: new device frequency | |
245 | * | |
246 | * Reconfigure and reprogram a clock event device in oneshot | |
247 | * mode. Must be called on the cpu for which the device delivers per | |
248 | * cpu timer events with interrupts disabled! Returns 0 on success, | |
249 | * -ETIME when the event is in the past. | |
250 | */ | |
251 | int clockevents_update_freq(struct clock_event_device *dev, u32 freq) | |
252 | { | |
253 | clockevents_config(dev, freq); | |
254 | ||
255 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) | |
256 | return 0; | |
257 | ||
258 | return clockevents_program_event(dev, dev->next_event, ktime_get()); | |
259 | } | |
260 | ||
d316c57f TG |
261 | /* |
262 | * Noop handler when we shut down an event device | |
263 | */ | |
7c1e7689 | 264 | void clockevents_handle_noop(struct clock_event_device *dev) |
d316c57f TG |
265 | { |
266 | } | |
267 | ||
268 | /** | |
269 | * clockevents_exchange_device - release and request clock devices | |
270 | * @old: device to release (can be NULL) | |
271 | * @new: device to request (can be NULL) | |
272 | * | |
273 | * Called from the notifier chain. clockevents_lock is held already | |
274 | */ | |
275 | void clockevents_exchange_device(struct clock_event_device *old, | |
276 | struct clock_event_device *new) | |
277 | { | |
278 | unsigned long flags; | |
279 | ||
280 | local_irq_save(flags); | |
281 | /* | |
282 | * Caller releases a clock event device. We queue it into the | |
283 | * released list and do a notify add later. | |
284 | */ | |
285 | if (old) { | |
d316c57f TG |
286 | clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); |
287 | list_del(&old->list); | |
288 | list_add(&old->list, &clockevents_released); | |
289 | } | |
290 | ||
291 | if (new) { | |
292 | BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); | |
2344abbc | 293 | clockevents_shutdown(new); |
d316c57f TG |
294 | } |
295 | local_irq_restore(flags); | |
296 | } | |
297 | ||
de68d9b1 | 298 | #ifdef CONFIG_GENERIC_CLOCKEVENTS |
d316c57f TG |
299 | /** |
300 | * clockevents_notify - notification about relevant events | |
301 | */ | |
302 | void clockevents_notify(unsigned long reason, void *arg) | |
303 | { | |
bb6eddf7 | 304 | struct clock_event_device *dev, *tmp; |
f833bab8 | 305 | unsigned long flags; |
bb6eddf7 | 306 | int cpu; |
0b858e6f | 307 | |
b5f91da0 | 308 | raw_spin_lock_irqsave(&clockevents_lock, flags); |
d316c57f TG |
309 | clockevents_do_notify(reason, arg); |
310 | ||
311 | switch (reason) { | |
312 | case CLOCK_EVT_NOTIFY_CPU_DEAD: | |
313 | /* | |
314 | * Unregister the clock event devices which were | |
315 | * released from the users in the notify chain. | |
316 | */ | |
bb6eddf7 TG |
317 | list_for_each_entry_safe(dev, tmp, &clockevents_released, list) |
318 | list_del(&dev->list); | |
319 | /* | |
320 | * Now check whether the CPU has left unused per cpu devices | |
321 | */ | |
322 | cpu = *((int *)arg); | |
323 | list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) { | |
324 | if (cpumask_test_cpu(cpu, dev->cpumask) && | |
ea9d8e3f XF |
325 | cpumask_weight(dev->cpumask) == 1 && |
326 | !tick_is_broadcast_device(dev)) { | |
bb6eddf7 TG |
327 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); |
328 | list_del(&dev->list); | |
329 | } | |
330 | } | |
d316c57f TG |
331 | break; |
332 | default: | |
333 | break; | |
334 | } | |
b5f91da0 | 335 | raw_spin_unlock_irqrestore(&clockevents_lock, flags); |
d316c57f TG |
336 | } |
337 | EXPORT_SYMBOL_GPL(clockevents_notify); | |
de68d9b1 | 338 | #endif |