drivers/rtc/interface.c

   1 /*
   2  * RTC subsystem, interface functions
   3  *
   4  * Copyright (C) 2005 Tower Technologies
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   6  *
   7  * based on arch/arm/common/rtctime.c
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12 */
  13
  14 #include <linux/rtc.h>
  15 #include <linux/sched.h>
  16 #include <linux/log2.h>
  17 #include <linux/workqueue.h>
  18
  19 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  20 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  21
  22 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  23 {
  24         int err;
  25         if (!rtc->ops)
  26                 err = -ENODEV;
  27         else if (!rtc->ops->read_time)
  28                 err = -EINVAL;
  29         else {
  30                 memset(tm, 0, sizeof(struct rtc_time));
  31                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  32         }
  33         return err;
  34 }
  35
  36 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  37 {
  38         int err;
  39
  40         err = mutex_lock_interruptible(&rtc->ops_lock);
  41         if (err)
  42                 return err;
  43
  44         err = __rtc_read_time(rtc, tm);
  45         mutex_unlock(&rtc->ops_lock);
  46         return err;
  47 }
  48 EXPORT_SYMBOL_GPL(rtc_read_time);
  49
  50 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  51 {
  52         int err;
  53
  54         err = rtc_valid_tm(tm);
  55         if (err != 0)
  56                 return err;
  57
  58         err = mutex_lock_interruptible(&rtc->ops_lock);
  59         if (err)
  60                 return err;
  61
  62         if (!rtc->ops)
  63                 err = -ENODEV;
  64         else if (rtc->ops->set_time)
  65                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  66         else if (rtc->ops->set_mmss) {
  67                 unsigned long secs;
  68                 err = rtc_tm_to_time(tm, &secs);
  69                 if (err == 0)
  70                         err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  71         } else
  72                 err = -EINVAL;
  73
  74         mutex_unlock(&rtc->ops_lock);
  75         return err;
  76 }
  77 EXPORT_SYMBOL_GPL(rtc_set_time);
  78
  79 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  80 {
  81         int err;
  82
  83         err = mutex_lock_interruptible(&rtc->ops_lock);
  84         if (err)
  85                 return err;
  86
  87         if (!rtc->ops)
  88                 err = -ENODEV;
  89         else if (rtc->ops->set_mmss)
  90                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  91         else if (rtc->ops->read_time && rtc->ops->set_time) {
  92                 struct rtc_time new, old;
  93
  94                 err = rtc->ops->read_time(rtc->dev.parent, &old);
  95                 if (err == 0) {
  96                         rtc_time_to_tm(secs, &new);
  97
  98                         /*
  99                          * avoid writing when we're going to change the day of
 100                          * the month. We will retry in the next minute. This
 101                          * basically means that if the RTC must not drift
 102                          * by more than 1 minute in 11 minutes.
 103                          */
 104                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 105                                 (new.tm_hour == 23 && new.tm_min == 59)))
 106                                 err = rtc->ops->set_time(rtc->dev.parent,
 107                                                 &new);
 108                 }
 109         }
 110         else
 111                 err = -EINVAL;
 112
 113         mutex_unlock(&rtc->ops_lock);
 114
 115         return err;
 116 }
 117 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 118
 119 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 120 {
 121         int err;
 122
 123         err = mutex_lock_interruptible(&rtc->ops_lock);
 124         if (err)
 125                 return err;
 126         if (rtc->ops == NULL)
 127                 err = -ENODEV;
 128         else if (!rtc->ops->read_alarm)
 129                 err = -EINVAL;
 130         else {
 131                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 132                 alarm->enabled = rtc->aie_timer.enabled;
 133                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 134         }
 135         mutex_unlock(&rtc->ops_lock);
 136
 137         return err;
 138 }
 139 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 140
 141 int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 142 {
 143         struct rtc_time tm;
 144         long now, scheduled;
 145         int err;
 146
 147         err = rtc_valid_tm(&alarm->time);
 148         if (err)
 149                 return err;
 150         rtc_tm_to_time(&alarm->time, &scheduled);
 151
 152         /* Make sure we're not setting alarms in the past */
 153         err = __rtc_read_time(rtc, &tm);
 154         rtc_tm_to_time(&tm, &now);
 155         if (scheduled <= now)
 156                 return -ETIME;
 157         /*
 158          * XXX - We just checked to make sure the alarm time is not
 159          * in the past, but there is still a race window where if
 160          * the is alarm set for the next second and the second ticks
 161          * over right here, before we set the alarm.
 162          */
 163
 164         if (!rtc->ops)
 165                 err = -ENODEV;
 166         else if (!rtc->ops->set_alarm)
 167                 err = -EINVAL;
 168         else
 169                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 170
 171         return err;
 172 }
 173
 174 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 175 {
 176         int err;
 177
 178         err = rtc_valid_tm(&alarm->time);
 179         if (err != 0)
 180                 return err;
 181
 182         err = mutex_lock_interruptible(&rtc->ops_lock);
 183         if (err)
 184                 return err;
 185         if (rtc->aie_timer.enabled) {
 186                 rtc_timer_remove(rtc, &rtc->aie_timer);
 187         }
 188         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 189         rtc->aie_timer.period = ktime_set(0, 0);
 190         if (alarm->enabled) {
 191                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 192         }
 193         mutex_unlock(&rtc->ops_lock);
 194         return err;
 195 }
 196 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 197
 198 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 199 {
 200         int err = mutex_lock_interruptible(&rtc->ops_lock);
 201         if (err)
 202                 return err;
 203
 204         if (rtc->aie_timer.enabled != enabled) {
 205                 if (enabled)
 206                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 207                 else
 208                         rtc_timer_remove(rtc, &rtc->aie_timer);
 209         }
 210
 211         if (err)
 212                 return err;
 213
 214         if (!rtc->ops)
 215                 err = -ENODEV;
 216         else if (!rtc->ops->alarm_irq_enable)
 217                 err = -EINVAL;
 218         else
 219                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 220
 221         mutex_unlock(&rtc->ops_lock);
 222         return err;
 223 }
 224 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 225
 226 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 227 {
 228         int err = mutex_lock_interruptible(&rtc->ops_lock);
 229         if (err)
 230                 return err;
 231
 232         /* make sure we're changing state */
 233         if (rtc->uie_rtctimer.enabled == enabled)
 234                 goto out;
 235
 236         if (enabled) {
 237                 struct rtc_time tm;
 238                 ktime_t now, onesec;
 239
 240                 __rtc_read_time(rtc, &tm);
 241                 onesec = ktime_set(1, 0);
 242                 now = rtc_tm_to_ktime(tm);
 243                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 244                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 245                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 246         } else
 247                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 248
 249 out:
 250         mutex_unlock(&rtc->ops_lock);
 251         return err;
 252
 253 }
 254 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 255
 256
 257 /**
 258  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 259  * @rtc: pointer to the rtc device
 260  *
 261  * This function is called when an AIE, UIE or PIE mode interrupt
 262  * has occured (or been emulated).
 263  *
 264  * Triggers the registered irq_task function callback.
 265  */
 266 static void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 267 {
 268         unsigned long flags;
 269
 270         /* mark one irq of the appropriate mode */
 271         spin_lock_irqsave(&rtc->irq_lock, flags);
 272         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 273         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 274
 275         /* call the task func */
 276         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 277         if (rtc->irq_task)
 278                 rtc->irq_task->func(rtc->irq_task->private_data);
 279         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 280
 281         wake_up_interruptible(&rtc->irq_queue);
 282         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 283 }
 284
 285
 286 /**
 287  * rtc_aie_update_irq - AIE mode rtctimer hook
 288  * @private: pointer to the rtc_device
 289  *
 290  * This functions is called when the aie_timer expires.
 291  */
 292 void rtc_aie_update_irq(void *private)
 293 {
 294         struct rtc_device *rtc = (struct rtc_device *)private;
 295         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 296 }
 297
 298
 299 /**
 300  * rtc_uie_update_irq - UIE mode rtctimer hook
 301  * @private: pointer to the rtc_device
 302  *
 303  * This functions is called when the uie_timer expires.
 304  */
 305 void rtc_uie_update_irq(void *private)
 306 {
 307         struct rtc_device *rtc = (struct rtc_device *)private;
 308         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 309 }
 310
 311
 312 /**
 313  * rtc_pie_update_irq - PIE mode hrtimer hook
 314  * @timer: pointer to the pie mode hrtimer
 315  *
 316  * This function is used to emulate PIE mode interrupts
 317  * using an hrtimer. This function is called when the periodic
 318  * hrtimer expires.
 319  */
 320 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 321 {
 322         struct rtc_device *rtc;
 323         ktime_t period;
 324         int count;
 325         rtc = container_of(timer, struct rtc_device, pie_timer);
 326
 327         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 328         count = hrtimer_forward_now(timer, period);
 329
 330         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 331
 332         return HRTIMER_RESTART;
 333 }
 334
 335 /**
 336  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 337  * @rtc: the rtc device
 338  * @num: how many irqs are being reported (usually one)
 339  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 340  * Context: any
 341  */
 342 void rtc_update_irq(struct rtc_device *rtc,
 343                 unsigned long num, unsigned long events)
 344 {
 345         schedule_work(&rtc->irqwork);
 346 }
 347 EXPORT_SYMBOL_GPL(rtc_update_irq);
 348
 349 static int __rtc_match(struct device *dev, void *data)
 350 {
 351         char *name = (char *)data;
 352
 353         if (strcmp(dev_name(dev), name) == 0)
 354                 return 1;
 355         return 0;
 356 }
 357
 358 struct rtc_device *rtc_class_open(char *name)
 359 {
 360         struct device *dev;
 361         struct rtc_device *rtc = NULL;
 362
 363         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 364         if (dev)
 365                 rtc = to_rtc_device(dev);
 366
 367         if (rtc) {
 368                 if (!try_module_get(rtc->owner)) {
 369                         put_device(dev);
 370                         rtc = NULL;
 371                 }
 372         }
 373
 374         return rtc;
 375 }
 376 EXPORT_SYMBOL_GPL(rtc_class_open);
 377
 378 void rtc_class_close(struct rtc_device *rtc)
 379 {
 380         module_put(rtc->owner);
 381         put_device(&rtc->dev);
 382 }
 383 EXPORT_SYMBOL_GPL(rtc_class_close);
 384
 385 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 386 {
 387         int retval = -EBUSY;
 388
 389         if (task == NULL || task->func == NULL)
 390                 return -EINVAL;
 391
 392         /* Cannot register while the char dev is in use */
 393         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 394                 return -EBUSY;
 395
 396         spin_lock_irq(&rtc->irq_task_lock);
 397         if (rtc->irq_task == NULL) {
 398                 rtc->irq_task = task;
 399                 retval = 0;
 400         }
 401         spin_unlock_irq(&rtc->irq_task_lock);
 402
 403         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 404
 405         return retval;
 406 }
 407 EXPORT_SYMBOL_GPL(rtc_irq_register);
 408
 409 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 410 {
 411         spin_lock_irq(&rtc->irq_task_lock);
 412         if (rtc->irq_task == task)
 413                 rtc->irq_task = NULL;
 414         spin_unlock_irq(&rtc->irq_task_lock);
 415 }
 416 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 417
 418 /**
 419  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 420  * @rtc: the rtc device
 421  * @task: currently registered with rtc_irq_register()
 422  * @enabled: true to enable periodic IRQs
 423  * Context: any
 424  *
 425  * Note that rtc_irq_set_freq() should previously have been used to
 426  * specify the desired frequency of periodic IRQ task->func() callbacks.
 427  */
 428 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 429 {
 430         int err = 0;
 431         unsigned long flags;
 432
 433         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 434         if (rtc->irq_task != NULL && task == NULL)
 435                 err = -EBUSY;
 436         if (rtc->irq_task != task)
 437                 err = -EACCES;
 438
 439         if (enabled) {
 440                 ktime_t period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 441                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 442         } else {
 443                 hrtimer_cancel(&rtc->pie_timer);
 444         }
 445         rtc->pie_enabled = enabled;
 446         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 447
 448         return err;
 449 }
 450 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 451
 452 /**
 453  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 454  * @rtc: the rtc device
 455  * @task: currently registered with rtc_irq_register()
 456  * @freq: positive frequency with which task->func() will be called
 457  * Context: any
 458  *
 459  * Note that rtc_irq_set_state() is used to enable or disable the
 460  * periodic IRQs.
 461  */
 462 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 463 {
 464         int err = 0;
 465         unsigned long flags;
 466
 467         if (freq <= 0)
 468                 return -EINVAL;
 469
 470         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 471         if (rtc->irq_task != NULL && task == NULL)
 472                 err = -EBUSY;
 473         if (rtc->irq_task != task)
 474                 err = -EACCES;
 475         if (err == 0) {
 476                 rtc->irq_freq = freq;
 477                 if (rtc->pie_enabled) {
 478                         ktime_t period;
 479                         hrtimer_cancel(&rtc->pie_timer);
 480                         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 481                         hrtimer_start(&rtc->pie_timer, period,
 482                                         HRTIMER_MODE_REL);
 483                 }
 484         }
 485         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 486         return err;
 487 }
 488 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 489
 490 /**
 491  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 492  * @rtc rtc device
 493  * @timer timer being added.
 494  *
 495  * Enqueues a timer onto the rtc devices timerqueue and sets
 496  * the next alarm event appropriately.
 497  *
 498  * Sets the enabled bit on the added timer.
 499  *
 500  * Must hold ops_lock for proper serialization of timerqueue
 501  */
 502 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 503 {
 504         timer->enabled = 1;
 505         timerqueue_add(&rtc->timerqueue, &timer->node);
 506         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 507                 struct rtc_wkalrm alarm;
 508                 int err;
 509                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 510                 alarm.enabled = 1;
 511                 err = __rtc_set_alarm(rtc, &alarm);
 512                 if (err == -ETIME)
 513                         schedule_work(&rtc->irqwork);
 514                 else if (err) {
 515                         timerqueue_del(&rtc->timerqueue, &timer->node);
 516                         timer->enabled = 0;
 517                         return err;
 518                 }
 519         }
 520         return 0;
 521 }
 522
 523 /**
 524  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 525  * @rtc rtc device
 526  * @timer timer being removed.
 527  *
 528  * Removes a timer onto the rtc devices timerqueue and sets
 529  * the next alarm event appropriately.
 530  *
 531  * Clears the enabled bit on the removed timer.
 532  *
 533  * Must hold ops_lock for proper serialization of timerqueue
 534  */
 535 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 536 {
 537         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 538         timerqueue_del(&rtc->timerqueue, &timer->node);
 539         timer->enabled = 0;
 540         if (next == &timer->node) {
 541                 struct rtc_wkalrm alarm;
 542                 int err;
 543                 next = timerqueue_getnext(&rtc->timerqueue);
 544                 if (!next)
 545                         return;
 546                 alarm.time = rtc_ktime_to_tm(next->expires);
 547                 alarm.enabled = 1;
 548                 err = __rtc_set_alarm(rtc, &alarm);
 549                 if (err == -ETIME)
 550                         schedule_work(&rtc->irqwork);
 551         }
 552 }
 553
 554 /**
 555  * rtc_timer_do_work - Expires rtc timers
 556  * @rtc rtc device
 557  * @timer timer being removed.
 558  *
 559  * Expires rtc timers. Reprograms next alarm event if needed.
 560  * Called via worktask.
 561  *
 562  * Serializes access to timerqueue via ops_lock mutex
 563  */
 564 void rtc_timer_do_work(struct work_struct *work)
 565 {
 566         struct rtc_timer *timer;
 567         struct timerqueue_node *next;
 568         ktime_t now;
 569         struct rtc_time tm;
 570
 571         struct rtc_device *rtc =
 572                 container_of(work, struct rtc_device, irqwork);
 573
 574         mutex_lock(&rtc->ops_lock);
 575 again:
 576         __rtc_read_time(rtc, &tm);
 577         now = rtc_tm_to_ktime(tm);
 578         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 579                 if (next->expires.tv64 > now.tv64)
 580                         break;
 581
 582                 /* expire timer */
 583                 timer = container_of(next, struct rtc_timer, node);
 584                 timerqueue_del(&rtc->timerqueue, &timer->node);
 585                 timer->enabled = 0;
 586                 if (timer->task.func)
 587                         timer->task.func(timer->task.private_data);
 588
 589                 /* Re-add/fwd periodic timers */
 590                 if (ktime_to_ns(timer->period)) {
 591                         timer->node.expires = ktime_add(timer->node.expires,
 592                                                         timer->period);
 593                         timer->enabled = 1;
 594                         timerqueue_add(&rtc->timerqueue, &timer->node);
 595                 }
 596         }
 597
 598         /* Set next alarm */
 599         if (next) {
 600                 struct rtc_wkalrm alarm;
 601                 int err;
 602                 alarm.time = rtc_ktime_to_tm(next->expires);
 603                 alarm.enabled = 1;
 604                 err = __rtc_set_alarm(rtc, &alarm);
 605                 if (err == -ETIME)
 606                         goto again;
 607         }
 608
 609         mutex_unlock(&rtc->ops_lock);
 610 }
 611
 612
 613 /* rtc_timer_init - Initializes an rtc_timer
 614  * @timer: timer to be intiialized
 615  * @f: function pointer to be called when timer fires
 616  * @data: private data passed to function pointer
 617  *
 618  * Kernel interface to initializing an rtc_timer.
 619  */
 620 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data)
 621 {
 622         timerqueue_init(&timer->node);
 623         timer->enabled = 0;
 624         timer->task.func = f;
 625         timer->task.private_data = data;
 626 }
 627
 628 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 629  * @ rtc: rtc device to be used
 630  * @ timer: timer being set
 631  * @ expires: time at which to expire the timer
 632  * @ period: period that the timer will recur
 633  *
 634  * Kernel interface to set an rtc_timer
 635  */
 636 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
 637                         ktime_t expires, ktime_t period)
 638 {
 639         int ret = 0;
 640         mutex_lock(&rtc->ops_lock);
 641         if (timer->enabled)
 642                 rtc_timer_remove(rtc, timer);
 643
 644         timer->node.expires = expires;
 645         timer->period = period;
 646
 647         ret = rtc_timer_enqueue(rtc, timer);
 648
 649         mutex_unlock(&rtc->ops_lock);
 650         return ret;
 651 }
 652
 653 /* rtc_timer_cancel - Stops an rtc_timer
 654  * @ rtc: rtc device to be used
 655  * @ timer: timer being set
 656  *
 657  * Kernel interface to cancel an rtc_timer
 658  */
 659 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
 660 {
 661         int ret = 0;
 662         mutex_lock(&rtc->ops_lock);
 663         if (timer->enabled)
 664                 rtc_timer_remove(rtc, timer);
 665         mutex_unlock(&rtc->ops_lock);
 666         return ret;
 667 }
 668
 669