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ff3ead96 JS |
1 | /* |
2 | * Alarmtimer interface | |
3 | * | |
4 | * This interface provides a timer which is similarto hrtimers, | |
5 | * but triggers a RTC alarm if the box is suspend. | |
6 | * | |
7 | * This interface is influenced by the Android RTC Alarm timer | |
8 | * interface. | |
9 | * | |
10 | * Copyright (C) 2010 IBM Corperation | |
11 | * | |
12 | * Author: John Stultz <john.stultz@linaro.org> | |
13 | * | |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License version 2 as | |
16 | * published by the Free Software Foundation. | |
17 | */ | |
18 | #include <linux/time.h> | |
19 | #include <linux/hrtimer.h> | |
20 | #include <linux/timerqueue.h> | |
21 | #include <linux/rtc.h> | |
22 | #include <linux/alarmtimer.h> | |
23 | #include <linux/mutex.h> | |
24 | #include <linux/platform_device.h> | |
25 | #include <linux/posix-timers.h> | |
26 | #include <linux/workqueue.h> | |
27 | #include <linux/freezer.h> | |
28 | ||
29 | ||
30 | static struct alarm_base { | |
31 | spinlock_t lock; | |
32 | struct timerqueue_head timerqueue; | |
33 | struct hrtimer timer; | |
34 | ktime_t (*gettime)(void); | |
35 | clockid_t base_clockid; | |
36 | struct work_struct irqwork; | |
37 | } alarm_bases[ALARM_NUMTYPE]; | |
38 | ||
39 | static struct rtc_timer rtctimer; | |
40 | static struct rtc_device *rtcdev; | |
41 | ||
42 | static ktime_t freezer_delta; | |
43 | static DEFINE_SPINLOCK(freezer_delta_lock); | |
44 | ||
45 | ||
46 | /************************************************************************** | |
47 | * alarmtimer management code | |
48 | */ | |
49 | ||
50 | /* | |
51 | * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue | |
52 | * @base: pointer to the base where the timer is being run | |
53 | * @alarm: pointer to alarm being enqueued. | |
54 | * | |
55 | * Adds alarm to a alarm_base timerqueue and if necessary sets | |
56 | * an hrtimer to run. | |
57 | * | |
58 | * Must hold base->lock when calling. | |
59 | */ | |
60 | static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) | |
61 | { | |
62 | timerqueue_add(&base->timerqueue, &alarm->node); | |
63 | if (&alarm->node == timerqueue_getnext(&base->timerqueue)) { | |
64 | hrtimer_try_to_cancel(&base->timer); | |
65 | hrtimer_start(&base->timer, alarm->node.expires, | |
66 | HRTIMER_MODE_ABS); | |
67 | } | |
68 | } | |
69 | ||
70 | /* | |
71 | * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue | |
72 | * @base: pointer to the base where the timer is running | |
73 | * @alarm: pointer to alarm being removed | |
74 | * | |
75 | * Removes alarm to a alarm_base timerqueue and if necessary sets | |
76 | * a new timer to run. | |
77 | * | |
78 | * Must hold base->lock when calling. | |
79 | */ | |
80 | static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) | |
81 | { | |
82 | struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue); | |
83 | ||
84 | timerqueue_del(&base->timerqueue, &alarm->node); | |
85 | if (next == &alarm->node) { | |
86 | hrtimer_try_to_cancel(&base->timer); | |
87 | next = timerqueue_getnext(&base->timerqueue); | |
88 | if (!next) | |
89 | return; | |
90 | hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS); | |
91 | } | |
92 | } | |
93 | ||
94 | /* | |
95 | * alarmtimer_do_work - Handles alarm being fired. | |
96 | * @work: pointer to workqueue being run | |
97 | * | |
98 | * When a timer fires, this runs through the timerqueue to see | |
99 | * which alarm timers, and run those that expired. If there are | |
100 | * more alarm timers queued, we set the hrtimer to fire in the | |
101 | * future. | |
102 | */ | |
103 | void alarmtimer_do_work(struct work_struct *work) | |
104 | { | |
105 | struct alarm_base *base = container_of(work, struct alarm_base, | |
106 | irqwork); | |
107 | struct timerqueue_node *next; | |
108 | unsigned long flags; | |
109 | ktime_t now; | |
110 | ||
111 | spin_lock_irqsave(&base->lock, flags); | |
112 | now = base->gettime(); | |
113 | while ((next = timerqueue_getnext(&base->timerqueue))) { | |
114 | struct alarm *alarm; | |
115 | ktime_t expired = next->expires; | |
116 | ||
117 | if (expired.tv64 >= now.tv64) | |
118 | break; | |
119 | ||
120 | alarm = container_of(next, struct alarm, node); | |
121 | ||
122 | timerqueue_del(&base->timerqueue, &alarm->node); | |
123 | alarm->enabled = 0; | |
124 | /* Re-add periodic timers */ | |
125 | if (alarm->period.tv64) { | |
126 | alarm->node.expires = ktime_add(expired, alarm->period); | |
127 | timerqueue_add(&base->timerqueue, &alarm->node); | |
128 | alarm->enabled = 1; | |
129 | } | |
130 | spin_unlock_irqrestore(&base->lock, flags); | |
131 | if (alarm->function) | |
132 | alarm->function(alarm); | |
133 | spin_lock_irqsave(&base->lock, flags); | |
134 | } | |
135 | ||
136 | if (next) { | |
137 | hrtimer_start(&base->timer, next->expires, | |
138 | HRTIMER_MODE_ABS); | |
139 | } | |
140 | spin_unlock_irqrestore(&base->lock, flags); | |
141 | } | |
142 | ||
143 | ||
144 | /* | |
145 | * alarmtimer_fired - Handles alarm hrtimer being fired. | |
146 | * @timer: pointer to hrtimer being run | |
147 | * | |
148 | * When a timer fires, this schedules the do_work function to | |
149 | * be run. | |
150 | */ | |
151 | static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer) | |
152 | { | |
153 | struct alarm_base *base = container_of(timer, struct alarm_base, timer); | |
154 | schedule_work(&base->irqwork); | |
155 | return HRTIMER_NORESTART; | |
156 | } | |
157 | ||
158 | ||
159 | /* | |
160 | * alarmtimer_suspend - Suspend time callback | |
161 | * @dev: unused | |
162 | * @state: unused | |
163 | * | |
164 | * When we are going into suspend, we look through the bases | |
165 | * to see which is the soonest timer to expire. We then | |
166 | * set an rtc timer to fire that far into the future, which | |
167 | * will wake us from suspend. | |
168 | */ | |
169 | static int alarmtimer_suspend(struct device *dev) | |
170 | { | |
171 | struct rtc_time tm; | |
172 | ktime_t min, now; | |
173 | unsigned long flags; | |
174 | int i; | |
175 | ||
176 | spin_lock_irqsave(&freezer_delta_lock, flags); | |
177 | min = freezer_delta; | |
178 | freezer_delta = ktime_set(0, 0); | |
179 | spin_unlock_irqrestore(&freezer_delta_lock, flags); | |
180 | ||
181 | /* If we have no rtcdev, just return */ | |
182 | if (!rtcdev) | |
183 | return 0; | |
184 | ||
185 | /* Find the soonest timer to expire*/ | |
186 | for (i = 0; i < ALARM_NUMTYPE; i++) { | |
187 | struct alarm_base *base = &alarm_bases[i]; | |
188 | struct timerqueue_node *next; | |
189 | ktime_t delta; | |
190 | ||
191 | spin_lock_irqsave(&base->lock, flags); | |
192 | next = timerqueue_getnext(&base->timerqueue); | |
193 | spin_unlock_irqrestore(&base->lock, flags); | |
194 | if (!next) | |
195 | continue; | |
196 | delta = ktime_sub(next->expires, base->gettime()); | |
197 | if (!min.tv64 || (delta.tv64 < min.tv64)) | |
198 | min = delta; | |
199 | } | |
200 | if (min.tv64 == 0) | |
201 | return 0; | |
202 | ||
203 | /* XXX - Should we enforce a minimum sleep time? */ | |
204 | WARN_ON(min.tv64 < NSEC_PER_SEC); | |
205 | ||
206 | /* Setup an rtc timer to fire that far in the future */ | |
207 | rtc_timer_cancel(rtcdev, &rtctimer); | |
208 | rtc_read_time(rtcdev, &tm); | |
209 | now = rtc_tm_to_ktime(tm); | |
210 | now = ktime_add(now, min); | |
211 | ||
212 | rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0)); | |
213 | ||
214 | return 0; | |
215 | } | |
216 | ||
217 | ||
218 | /************************************************************************** | |
219 | * alarm kernel interface code | |
220 | */ | |
221 | ||
222 | /* | |
223 | * alarm_init - Initialize an alarm structure | |
224 | * @alarm: ptr to alarm to be initialized | |
225 | * @type: the type of the alarm | |
226 | * @function: callback that is run when the alarm fires | |
227 | * | |
228 | * In-kernel interface to initializes the alarm structure. | |
229 | */ | |
230 | void alarm_init(struct alarm *alarm, enum alarmtimer_type type, | |
231 | void (*function)(struct alarm *)) | |
232 | { | |
233 | timerqueue_init(&alarm->node); | |
234 | alarm->period = ktime_set(0, 0); | |
235 | alarm->function = function; | |
236 | alarm->type = type; | |
237 | alarm->enabled = 0; | |
238 | } | |
239 | ||
240 | /* | |
241 | * alarm_start - Sets an alarm to fire | |
242 | * @alarm: ptr to alarm to set | |
243 | * @start: time to run the alarm | |
244 | * @period: period at which the alarm will recur | |
245 | * | |
246 | * In-kernel interface set an alarm timer. | |
247 | */ | |
248 | void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period) | |
249 | { | |
250 | struct alarm_base *base = &alarm_bases[alarm->type]; | |
251 | unsigned long flags; | |
252 | ||
253 | spin_lock_irqsave(&base->lock, flags); | |
254 | if (alarm->enabled) | |
255 | alarmtimer_remove(base, alarm); | |
256 | alarm->node.expires = start; | |
257 | alarm->period = period; | |
258 | alarmtimer_enqueue(base, alarm); | |
259 | alarm->enabled = 1; | |
260 | spin_unlock_irqrestore(&base->lock, flags); | |
261 | } | |
262 | ||
263 | /* | |
264 | * alarm_cancel - Tries to cancel an alarm timer | |
265 | * @alarm: ptr to alarm to be canceled | |
266 | * | |
267 | * In-kernel interface to cancel an alarm timer. | |
268 | */ | |
269 | void alarm_cancel(struct alarm *alarm) | |
270 | { | |
271 | struct alarm_base *base = &alarm_bases[alarm->type]; | |
272 | unsigned long flags; | |
273 | ||
274 | spin_lock_irqsave(&base->lock, flags); | |
275 | if (alarm->enabled) | |
276 | alarmtimer_remove(base, alarm); | |
277 | alarm->enabled = 0; | |
278 | spin_unlock_irqrestore(&base->lock, flags); | |
279 | } | |
280 | ||
281 | ||
282 | ||
283 | /************************************************************************** | |
284 | * alarmtimer initialization code | |
285 | */ | |
286 | ||
287 | /* Suspend hook structures */ | |
288 | static const struct dev_pm_ops alarmtimer_pm_ops = { | |
289 | .suspend = alarmtimer_suspend, | |
290 | }; | |
291 | ||
292 | static struct platform_driver alarmtimer_driver = { | |
293 | .driver = { | |
294 | .name = "alarmtimer", | |
295 | .pm = &alarmtimer_pm_ops, | |
296 | } | |
297 | }; | |
298 | ||
299 | /** | |
300 | * alarmtimer_init - Initialize alarm timer code | |
301 | * | |
302 | * This function initializes the alarm bases and registers | |
303 | * the posix clock ids. | |
304 | */ | |
305 | static int __init alarmtimer_init(void) | |
306 | { | |
307 | int error = 0; | |
308 | int i; | |
309 | ||
310 | /* Initialize alarm bases */ | |
311 | alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME; | |
312 | alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real; | |
313 | alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME; | |
314 | alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime; | |
315 | for (i = 0; i < ALARM_NUMTYPE; i++) { | |
316 | timerqueue_init_head(&alarm_bases[i].timerqueue); | |
317 | spin_lock_init(&alarm_bases[i].lock); | |
318 | hrtimer_init(&alarm_bases[i].timer, | |
319 | alarm_bases[i].base_clockid, | |
320 | HRTIMER_MODE_ABS); | |
321 | alarm_bases[i].timer.function = alarmtimer_fired; | |
322 | INIT_WORK(&alarm_bases[i].irqwork, alarmtimer_do_work); | |
323 | } | |
324 | error = platform_driver_register(&alarmtimer_driver); | |
325 | platform_device_register_simple("alarmtimer", -1, NULL, 0); | |
326 | ||
327 | return error; | |
328 | } | |
329 | device_initcall(alarmtimer_init); | |
330 | ||
331 | /** | |
332 | * has_wakealarm - check rtc device has wakealarm ability | |
333 | * @dev: current device | |
334 | * @name_ptr: name to be returned | |
335 | * | |
336 | * This helper function checks to see if the rtc device can wake | |
337 | * from suspend. | |
338 | */ | |
339 | static int __init has_wakealarm(struct device *dev, void *name_ptr) | |
340 | { | |
341 | struct rtc_device *candidate = to_rtc_device(dev); | |
342 | ||
343 | if (!candidate->ops->set_alarm) | |
344 | return 0; | |
345 | if (!device_may_wakeup(candidate->dev.parent)) | |
346 | return 0; | |
347 | ||
348 | *(const char **)name_ptr = dev_name(dev); | |
349 | return 1; | |
350 | } | |
351 | ||
352 | /** | |
353 | * alarmtimer_init_late - Late initializing of alarmtimer code | |
354 | * | |
355 | * This function locates a rtc device to use for wakealarms. | |
356 | * Run as late_initcall to make sure rtc devices have been | |
357 | * registered. | |
358 | */ | |
359 | static int __init alarmtimer_init_late(void) | |
360 | { | |
361 | char *str; | |
362 | ||
363 | /* Find an rtc device and init the rtc_timer */ | |
364 | class_find_device(rtc_class, NULL, &str, has_wakealarm); | |
365 | if (str) | |
366 | rtcdev = rtc_class_open(str); | |
367 | if (!rtcdev) { | |
368 | printk(KERN_WARNING "No RTC device found, ALARM timers will" | |
369 | " not wake from suspend"); | |
370 | } | |
371 | rtc_timer_init(&rtctimer, NULL, NULL); | |
372 | ||
373 | return 0; | |
374 | } | |
375 | late_initcall(alarmtimer_init_late); |