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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 | ||
22 | /* The registered clock event devices */ | |
23 | static LIST_HEAD(clockevent_devices); | |
24 | static LIST_HEAD(clockevents_released); | |
25 | ||
26 | /* Notification for clock events */ | |
27 | static RAW_NOTIFIER_HEAD(clockevents_chain); | |
28 | ||
29 | /* Protection for the above */ | |
30 | static DEFINE_SPINLOCK(clockevents_lock); | |
31 | ||
32 | /** | |
33 | * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds | |
34 | * @latch: value to convert | |
35 | * @evt: pointer to clock event device descriptor | |
36 | * | |
37 | * Math helper, returns latch value converted to nanoseconds (bound checked) | |
38 | */ | |
39 | unsigned long clockevent_delta2ns(unsigned long latch, | |
40 | struct clock_event_device *evt) | |
41 | { | |
42 | u64 clc = ((u64) latch << evt->shift); | |
43 | ||
45fe4fe1 IM |
44 | if (unlikely(!evt->mult)) { |
45 | evt->mult = 1; | |
46 | WARN_ON(1); | |
47 | } | |
48 | ||
d316c57f TG |
49 | do_div(clc, evt->mult); |
50 | if (clc < 1000) | |
51 | clc = 1000; | |
52 | if (clc > LONG_MAX) | |
53 | clc = LONG_MAX; | |
54 | ||
55 | return (unsigned long) clc; | |
56 | } | |
57 | ||
58 | /** | |
59 | * clockevents_set_mode - set the operating mode of a clock event device | |
60 | * @dev: device to modify | |
61 | * @mode: new mode | |
62 | * | |
63 | * Must be called with interrupts disabled ! | |
64 | */ | |
65 | void clockevents_set_mode(struct clock_event_device *dev, | |
66 | enum clock_event_mode mode) | |
67 | { | |
68 | if (dev->mode != mode) { | |
69 | dev->set_mode(mode, dev); | |
70 | dev->mode = mode; | |
71 | } | |
72 | } | |
73 | ||
2344abbc TG |
74 | /** |
75 | * clockevents_shutdown - shutdown the device and clear next_event | |
76 | * @dev: device to shutdown | |
77 | */ | |
78 | void clockevents_shutdown(struct clock_event_device *dev) | |
79 | { | |
80 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); | |
81 | dev->next_event.tv64 = KTIME_MAX; | |
82 | } | |
83 | ||
d316c57f TG |
84 | /** |
85 | * clockevents_program_event - Reprogram the clock event device. | |
86 | * @expires: absolute expiry time (monotonic clock) | |
87 | * | |
88 | * Returns 0 on success, -ETIME when the event is in the past. | |
89 | */ | |
90 | int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, | |
91 | ktime_t now) | |
92 | { | |
93 | unsigned long long clc; | |
94 | int64_t delta; | |
95 | ||
167b1de3 TG |
96 | if (unlikely(expires.tv64 < 0)) { |
97 | WARN_ON_ONCE(1); | |
98 | return -ETIME; | |
99 | } | |
100 | ||
d316c57f TG |
101 | delta = ktime_to_ns(ktime_sub(expires, now)); |
102 | ||
103 | if (delta <= 0) | |
104 | return -ETIME; | |
105 | ||
106 | dev->next_event = expires; | |
107 | ||
108 | if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN) | |
109 | return 0; | |
110 | ||
111 | if (delta > dev->max_delta_ns) | |
112 | delta = dev->max_delta_ns; | |
113 | if (delta < dev->min_delta_ns) | |
114 | delta = dev->min_delta_ns; | |
115 | ||
116 | clc = delta * dev->mult; | |
117 | clc >>= dev->shift; | |
118 | ||
119 | return dev->set_next_event((unsigned long) clc, dev); | |
120 | } | |
121 | ||
122 | /** | |
123 | * clockevents_register_notifier - register a clock events change listener | |
124 | */ | |
125 | int clockevents_register_notifier(struct notifier_block *nb) | |
126 | { | |
127 | int ret; | |
128 | ||
129 | spin_lock(&clockevents_lock); | |
130 | ret = raw_notifier_chain_register(&clockevents_chain, nb); | |
131 | spin_unlock(&clockevents_lock); | |
132 | ||
133 | return ret; | |
134 | } | |
135 | ||
d316c57f TG |
136 | /* |
137 | * Notify about a clock event change. Called with clockevents_lock | |
138 | * held. | |
139 | */ | |
140 | static void clockevents_do_notify(unsigned long reason, void *dev) | |
141 | { | |
142 | raw_notifier_call_chain(&clockevents_chain, reason, dev); | |
143 | } | |
144 | ||
145 | /* | |
3eb05676 | 146 | * Called after a notify add to make devices available which were |
d316c57f TG |
147 | * released from the notifier call. |
148 | */ | |
149 | static void clockevents_notify_released(void) | |
150 | { | |
151 | struct clock_event_device *dev; | |
152 | ||
153 | while (!list_empty(&clockevents_released)) { | |
154 | dev = list_entry(clockevents_released.next, | |
155 | struct clock_event_device, list); | |
156 | list_del(&dev->list); | |
157 | list_add(&dev->list, &clockevent_devices); | |
158 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
159 | } | |
160 | } | |
161 | ||
162 | /** | |
163 | * clockevents_register_device - register a clock event device | |
164 | * @dev: device to register | |
165 | */ | |
166 | void clockevents_register_device(struct clock_event_device *dev) | |
167 | { | |
168 | BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); | |
45fe4fe1 IM |
169 | /* |
170 | * A nsec2cyc multiplicator of 0 is invalid and we'd crash | |
171 | * on it, so fix it up and emit a warning: | |
172 | */ | |
173 | if (unlikely(!dev->mult)) { | |
174 | dev->mult = 1; | |
175 | WARN_ON(1); | |
176 | } | |
d316c57f TG |
177 | |
178 | spin_lock(&clockevents_lock); | |
179 | ||
180 | list_add(&dev->list, &clockevent_devices); | |
181 | clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev); | |
182 | clockevents_notify_released(); | |
183 | ||
184 | spin_unlock(&clockevents_lock); | |
185 | } | |
186 | ||
187 | /* | |
188 | * Noop handler when we shut down an event device | |
189 | */ | |
7c1e7689 | 190 | void clockevents_handle_noop(struct clock_event_device *dev) |
d316c57f TG |
191 | { |
192 | } | |
193 | ||
194 | /** | |
195 | * clockevents_exchange_device - release and request clock devices | |
196 | * @old: device to release (can be NULL) | |
197 | * @new: device to request (can be NULL) | |
198 | * | |
199 | * Called from the notifier chain. clockevents_lock is held already | |
200 | */ | |
201 | void clockevents_exchange_device(struct clock_event_device *old, | |
202 | struct clock_event_device *new) | |
203 | { | |
204 | unsigned long flags; | |
205 | ||
206 | local_irq_save(flags); | |
207 | /* | |
208 | * Caller releases a clock event device. We queue it into the | |
209 | * released list and do a notify add later. | |
210 | */ | |
211 | if (old) { | |
d316c57f TG |
212 | clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED); |
213 | list_del(&old->list); | |
214 | list_add(&old->list, &clockevents_released); | |
215 | } | |
216 | ||
217 | if (new) { | |
218 | BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED); | |
2344abbc | 219 | clockevents_shutdown(new); |
d316c57f TG |
220 | } |
221 | local_irq_restore(flags); | |
222 | } | |
223 | ||
de68d9b1 | 224 | #ifdef CONFIG_GENERIC_CLOCKEVENTS |
d316c57f TG |
225 | /** |
226 | * clockevents_notify - notification about relevant events | |
227 | */ | |
228 | void clockevents_notify(unsigned long reason, void *arg) | |
229 | { | |
0b858e6f LZ |
230 | struct list_head *node, *tmp; |
231 | ||
d316c57f TG |
232 | spin_lock(&clockevents_lock); |
233 | clockevents_do_notify(reason, arg); | |
234 | ||
235 | switch (reason) { | |
236 | case CLOCK_EVT_NOTIFY_CPU_DEAD: | |
237 | /* | |
238 | * Unregister the clock event devices which were | |
239 | * released from the users in the notify chain. | |
240 | */ | |
0b858e6f LZ |
241 | list_for_each_safe(node, tmp, &clockevents_released) |
242 | list_del(node); | |
d316c57f TG |
243 | break; |
244 | default: | |
245 | break; | |
246 | } | |
247 | spin_unlock(&clockevents_lock); | |
248 | } | |
249 | EXPORT_SYMBOL_GPL(clockevents_notify); | |
de68d9b1 | 250 | #endif |