John Stultz | ff3ead9 | 2011-01-11 09:42:13 -0800 | [diff] [blame^] | 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); |