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/module.h>
  17 #include <linux/log2.h>
  18 #include <linux/workqueue.h>
  19
  20 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22
  23 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  24 {
  25         int err;
  26         if (!rtc->ops)
  27                 err = -ENODEV;
  28         else if (!rtc->ops->read_time)
  29                 err = -EINVAL;
  30         else {
  31                 memset(tm, 0, sizeof(struct rtc_time));
  32                 err = rtc->ops->read_time(rtc->dev.parent, tm);
  33         }
  34         return err;
  35 }
  36
  37 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  38 {
  39         int err;
  40
  41         err = mutex_lock_interruptible(&rtc->ops_lock);
  42         if (err)
  43                 return err;
  44
  45         err = __rtc_read_time(rtc, tm);
  46         mutex_unlock(&rtc->ops_lock);
  47         return err;
  48 }
  49 EXPORT_SYMBOL_GPL(rtc_read_time);
  50
  51 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  52 {
  53         int err;
  54
  55         err = rtc_valid_tm(tm);
  56         if (err != 0)
  57                 return err;
  58
  59         err = mutex_lock_interruptible(&rtc->ops_lock);
  60         if (err)
  61                 return err;
  62
  63         if (!rtc->ops)
  64                 err = -ENODEV;
  65         else if (rtc->ops->set_time)
  66                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  67         else if (rtc->ops->set_mmss) {
  68                 unsigned long secs;
  69                 err = rtc_tm_to_time(tm, &secs);
  70                 if (err == 0)
  71                         err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  72         } else
  73                 err = -EINVAL;
  74
  75         pm_stay_awake(rtc->dev.parent);
  76         mutex_unlock(&rtc->ops_lock);
  77         /* A timer might have just expired */
  78         schedule_work(&rtc->irqwork);
  79         return err;
  80 }
  81 EXPORT_SYMBOL_GPL(rtc_set_time);
  82
  83 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  84 {
  85         int err;
  86
  87         err = mutex_lock_interruptible(&rtc->ops_lock);
  88         if (err)
  89                 return err;
  90
  91         if (!rtc->ops)
  92                 err = -ENODEV;
  93         else if (rtc->ops->set_mmss)
  94                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  95         else if (rtc->ops->read_time && rtc->ops->set_time) {
  96                 struct rtc_time new, old;
  97
  98                 err = rtc->ops->read_time(rtc->dev.parent, &old);
  99                 if (err == 0) {
 100                         rtc_time_to_tm(secs, &new);
 101
 102                         /*
 103                          * avoid writing when we're going to change the day of
 104                          * the month. We will retry in the next minute. This
 105                          * basically means that if the RTC must not drift
 106                          * by more than 1 minute in 11 minutes.
 107                          */
 108                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 109                                 (new.tm_hour == 23 && new.tm_min == 59)))
 110                                 err = rtc->ops->set_time(rtc->dev.parent,
 111                                                 &new);
 112                 }
 113         } else {
 114                 err = -EINVAL;
 115         }
 116
 117         pm_stay_awake(rtc->dev.parent);
 118         mutex_unlock(&rtc->ops_lock);
 119         /* A timer might have just expired */
 120         schedule_work(&rtc->irqwork);
 121
 122         return err;
 123 }
 124 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 125
 126 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 127 {
 128         int err;
 129
 130         err = mutex_lock_interruptible(&rtc->ops_lock);
 131         if (err)
 132                 return err;
 133
 134         if (rtc->ops == NULL)
 135                 err = -ENODEV;
 136         else if (!rtc->ops->read_alarm)
 137                 err = -EINVAL;
 138         else {
 139                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 140                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 141         }
 142
 143         mutex_unlock(&rtc->ops_lock);
 144         return err;
 145 }
 146
 147 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 148 {
 149         int err;
 150         struct rtc_time before, now;
 151         int first_time = 1;
 152         unsigned long t_now, t_alm;
 153         enum { none, day, month, year } missing = none;
 154         unsigned days;
 155
 156         /* The lower level RTC driver may return -1 in some fields,
 157          * creating invalid alarm->time values, for reasons like:
 158          *
 159          *   - The hardware may not be capable of filling them in;
 160          *     many alarms match only on time-of-day fields, not
 161          *     day/month/year calendar data.
 162          *
 163          *   - Some hardware uses illegal values as "wildcard" match
 164          *     values, which non-Linux firmware (like a BIOS) may try
 165          *     to set up as e.g. "alarm 15 minutes after each hour".
 166          *     Linux uses only oneshot alarms.
 167          *
 168          * When we see that here, we deal with it by using values from
 169          * a current RTC timestamp for any missing (-1) values.  The
 170          * RTC driver prevents "periodic alarm" modes.
 171          *
 172          * But this can be racey, because some fields of the RTC timestamp
 173          * may have wrapped in the interval since we read the RTC alarm,
 174          * which would lead to us inserting inconsistent values in place
 175          * of the -1 fields.
 176          *
 177          * Reading the alarm and timestamp in the reverse sequence
 178          * would have the same race condition, and not solve the issue.
 179          *
 180          * So, we must first read the RTC timestamp,
 181          * then read the RTC alarm value,
 182          * and then read a second RTC timestamp.
 183          *
 184          * If any fields of the second timestamp have changed
 185          * when compared with the first timestamp, then we know
 186          * our timestamp may be inconsistent with that used by
 187          * the low-level rtc_read_alarm_internal() function.
 188          *
 189          * So, when the two timestamps disagree, we just loop and do
 190          * the process again to get a fully consistent set of values.
 191          *
 192          * This could all instead be done in the lower level driver,
 193          * but since more than one lower level RTC implementation needs it,
 194          * then it's probably best best to do it here instead of there..
 195          */
 196
 197         /* Get the "before" timestamp */
 198         err = rtc_read_time(rtc, &before);
 199         if (err < 0)
 200                 return err;
 201         do {
 202                 if (!first_time)
 203                         memcpy(&before, &now, sizeof(struct rtc_time));
 204                 first_time = 0;
 205
 206                 /* get the RTC alarm values, which may be incomplete */
 207                 err = rtc_read_alarm_internal(rtc, alarm);
 208                 if (err)
 209                         return err;
 210
 211                 /* full-function RTCs won't have such missing fields */
 212                 if (rtc_valid_tm(&alarm->time) == 0)
 213                         return 0;
 214
 215                 /* get the "after" timestamp, to detect wrapped fields */
 216                 err = rtc_read_time(rtc, &now);
 217                 if (err < 0)
 218                         return err;
 219
 220                 /* note that tm_sec is a "don't care" value here: */
 221         } while (   before.tm_min   != now.tm_min
 222                  || before.tm_hour  != now.tm_hour
 223                  || before.tm_mon   != now.tm_mon
 224                  || before.tm_year  != now.tm_year);
 225
 226         /* Fill in the missing alarm fields using the timestamp; we
 227          * know there's at least one since alarm->time is invalid.
 228          */
 229         if (alarm->time.tm_sec == -1)
 230                 alarm->time.tm_sec = now.tm_sec;
 231         if (alarm->time.tm_min == -1)
 232                 alarm->time.tm_min = now.tm_min;
 233         if (alarm->time.tm_hour == -1)
 234                 alarm->time.tm_hour = now.tm_hour;
 235
 236         /* For simplicity, only support date rollover for now */
 237         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 238                 alarm->time.tm_mday = now.tm_mday;
 239                 missing = day;
 240         }
 241         if ((unsigned)alarm->time.tm_mon >= 12) {
 242                 alarm->time.tm_mon = now.tm_mon;
 243                 if (missing == none)
 244                         missing = month;
 245         }
 246         if (alarm->time.tm_year == -1) {
 247                 alarm->time.tm_year = now.tm_year;
 248                 if (missing == none)
 249                         missing = year;
 250         }
 251
 252         /* with luck, no rollover is needed */
 253         rtc_tm_to_time(&now, &t_now);
 254         rtc_tm_to_time(&alarm->time, &t_alm);
 255         if (t_now < t_alm)
 256                 goto done;
 257
 258         switch (missing) {
 259
 260         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 261          * that will trigger at 5am will do so at 5am Tuesday, which
 262          * could also be in the next month or year.  This is a common
 263          * case, especially for PCs.
 264          */
 265         case day:
 266                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 267                 t_alm += 24 * 60 * 60;
 268                 rtc_time_to_tm(t_alm, &alarm->time);
 269                 break;
 270
 271         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 272          * be next month.  An alarm matching on the 30th, 29th, or 28th
 273          * may end up in the month after that!  Many newer PCs support
 274          * this type of alarm.
 275          */
 276         case month:
 277                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 278                 do {
 279                         if (alarm->time.tm_mon < 11)
 280                                 alarm->time.tm_mon++;
 281                         else {
 282                                 alarm->time.tm_mon = 0;
 283                                 alarm->time.tm_year++;
 284                         }
 285                         days = rtc_month_days(alarm->time.tm_mon,
 286                                         alarm->time.tm_year);
 287                 } while (days < alarm->time.tm_mday);
 288                 break;
 289
 290         /* Year rollover ... easy except for leap years! */
 291         case year:
 292                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 293                 do {
 294                         alarm->time.tm_year++;
 295                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 296                         && rtc_valid_tm(&alarm->time) != 0);
 297                 break;
 298
 299         default:
 300                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 301         }
 302
 303 done:
 304         err = rtc_valid_tm(&alarm->time);
 305
 306         if (err) {
 307                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 308                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 309                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 310                         alarm->time.tm_sec);
 311         }
 312
 313         return err;
 314 }
 315
 316 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 317 {
 318         int err;
 319
 320         err = mutex_lock_interruptible(&rtc->ops_lock);
 321         if (err)
 322                 return err;
 323         if (rtc->ops == NULL)
 324                 err = -ENODEV;
 325         else if (!rtc->ops->read_alarm)
 326                 err = -EINVAL;
 327         else {
 328                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 329                 alarm->enabled = rtc->aie_timer.enabled;
 330                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 331         }
 332         mutex_unlock(&rtc->ops_lock);
 333
 334         return err;
 335 }
 336 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 337
 338 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 339 {
 340         struct rtc_time tm;
 341         long now, scheduled;
 342         int err;
 343
 344         err = rtc_valid_tm(&alarm->time);
 345         if (err)
 346                 return err;
 347         rtc_tm_to_time(&alarm->time, &scheduled);
 348
 349         /* Make sure we're not setting alarms in the past */
 350         err = __rtc_read_time(rtc, &tm);
 351         if (err)
 352                 return err;
 353         rtc_tm_to_time(&tm, &now);
 354         if (scheduled <= now)
 355                 return -ETIME;
 356         /*
 357          * XXX - We just checked to make sure the alarm time is not
 358          * in the past, but there is still a race window where if
 359          * the is alarm set for the next second and the second ticks
 360          * over right here, before we set the alarm.
 361          */
 362
 363         if (!rtc->ops)
 364                 err = -ENODEV;
 365         else if (!rtc->ops->set_alarm)
 366                 err = -EINVAL;
 367         else
 368                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 369
 370         return err;
 371 }
 372
 373 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 374 {
 375         int err;
 376
 377         err = rtc_valid_tm(&alarm->time);
 378         if (err != 0)
 379                 return err;
 380
 381         err = mutex_lock_interruptible(&rtc->ops_lock);
 382         if (err)
 383                 return err;
 384         if (rtc->aie_timer.enabled)
 385                 rtc_timer_remove(rtc, &rtc->aie_timer);
 386
 387         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 388         rtc->aie_timer.period = ktime_set(0, 0);
 389         if (alarm->enabled)
 390                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 391
 392         mutex_unlock(&rtc->ops_lock);
 393         return err;
 394 }
 395 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 396
 397 /* Called once per device from rtc_device_register */
 398 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 399 {
 400         int err;
 401         struct rtc_time now;
 402
 403         err = rtc_valid_tm(&alarm->time);
 404         if (err != 0)
 405                 return err;
 406
 407         err = rtc_read_time(rtc, &now);
 408         if (err)
 409                 return err;
 410
 411         err = mutex_lock_interruptible(&rtc->ops_lock);
 412         if (err)
 413                 return err;
 414
 415         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 416         rtc->aie_timer.period = ktime_set(0, 0);
 417
 418         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 419         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 420                          rtc->aie_timer.node.expires.tv64)) {
 421
 422                 rtc->aie_timer.enabled = 1;
 423                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 424         }
 425         mutex_unlock(&rtc->ops_lock);
 426         return err;
 427 }
 428 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 429
 430
 431
 432 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 433 {
 434         int err = mutex_lock_interruptible(&rtc->ops_lock);
 435         if (err)
 436                 return err;
 437
 438         if (rtc->aie_timer.enabled != enabled) {
 439                 if (enabled)
 440                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 441                 else
 442                         rtc_timer_remove(rtc, &rtc->aie_timer);
 443         }
 444
 445         if (err)
 446                 /* nothing */;
 447         else if (!rtc->ops)
 448                 err = -ENODEV;
 449         else if (!rtc->ops->alarm_irq_enable)
 450                 err = -EINVAL;
 451         else
 452                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 453
 454         mutex_unlock(&rtc->ops_lock);
 455         return err;
 456 }
 457 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 458
 459 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 460 {
 461         int err = mutex_lock_interruptible(&rtc->ops_lock);
 462         if (err)
 463                 return err;
 464
 465 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 466         if (enabled == 0 && rtc->uie_irq_active) {
 467                 mutex_unlock(&rtc->ops_lock);
 468                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 469         }
 470 #endif
 471         /* make sure we're changing state */
 472         if (rtc->uie_rtctimer.enabled == enabled)
 473                 goto out;
 474
 475         if (rtc->uie_unsupported) {
 476                 err = -EINVAL;
 477                 goto out;
 478         }
 479
 480         if (enabled) {
 481                 struct rtc_time tm;
 482                 ktime_t now, onesec;
 483
 484                 __rtc_read_time(rtc, &tm);
 485                 onesec = ktime_set(1, 0);
 486                 now = rtc_tm_to_ktime(tm);
 487                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 488                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 489                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 490         } else
 491                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 492
 493 out:
 494         mutex_unlock(&rtc->ops_lock);
 495 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 496         /*
 497          * Enable emulation if the driver did not provide
 498          * the update_irq_enable function pointer or if returned
 499          * -EINVAL to signal that it has been configured without
 500          * interrupts or that are not available at the moment.
 501          */
 502         if (err == -EINVAL)
 503                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 504 #endif
 505         return err;
 506
 507 }
 508 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 509
 510
 511 /**
 512  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 513  * @rtc: pointer to the rtc device
 514  *
 515  * This function is called when an AIE, UIE or PIE mode interrupt
 516  * has occurred (or been emulated).
 517  *
 518  * Triggers the registered irq_task function callback.
 519  */
 520 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 521 {
 522         unsigned long flags;
 523
 524         /* mark one irq of the appropriate mode */
 525         spin_lock_irqsave(&rtc->irq_lock, flags);
 526         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 527         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 528
 529         /* call the task func */
 530         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 531         if (rtc->irq_task)
 532                 rtc->irq_task->func(rtc->irq_task->private_data);
 533         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 534
 535         wake_up_interruptible(&rtc->irq_queue);
 536         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 537 }
 538
 539
 540 /**
 541  * rtc_aie_update_irq - AIE mode rtctimer hook
 542  * @private: pointer to the rtc_device
 543  *
 544  * This functions is called when the aie_timer expires.
 545  */
 546 void rtc_aie_update_irq(void *private)
 547 {
 548         struct rtc_device *rtc = (struct rtc_device *)private;
 549         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 550 }
 551
 552
 553 /**
 554  * rtc_uie_update_irq - UIE mode rtctimer hook
 555  * @private: pointer to the rtc_device
 556  *
 557  * This functions is called when the uie_timer expires.
 558  */
 559 void rtc_uie_update_irq(void *private)
 560 {
 561         struct rtc_device *rtc = (struct rtc_device *)private;
 562         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 563 }
 564
 565
 566 /**
 567  * rtc_pie_update_irq - PIE mode hrtimer hook
 568  * @timer: pointer to the pie mode hrtimer
 569  *
 570  * This function is used to emulate PIE mode interrupts
 571  * using an hrtimer. This function is called when the periodic
 572  * hrtimer expires.
 573  */
 574 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 575 {
 576         struct rtc_device *rtc;
 577         ktime_t period;
 578         int count;
 579         rtc = container_of(timer, struct rtc_device, pie_timer);
 580
 581         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 582         count = hrtimer_forward_now(timer, period);
 583
 584         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 585
 586         return HRTIMER_RESTART;
 587 }
 588
 589 /**
 590  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 591  * @rtc: the rtc device
 592  * @num: how many irqs are being reported (usually one)
 593  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 594  * Context: any
 595  */
 596 void rtc_update_irq(struct rtc_device *rtc,
 597                 unsigned long num, unsigned long events)
 598 {
 599         if (unlikely(IS_ERR_OR_NULL(rtc)))
 600                 return;
 601
 602         pm_stay_awake(rtc->dev.parent);
 603         schedule_work(&rtc->irqwork);
 604 }
 605 EXPORT_SYMBOL_GPL(rtc_update_irq);
 606
 607 static int __rtc_match(struct device *dev, const void *data)
 608 {
 609         const char *name = data;
 610
 611         if (strcmp(dev_name(dev), name) == 0)
 612                 return 1;
 613         return 0;
 614 }
 615
 616 struct rtc_device *rtc_class_open(const char *name)
 617 {
 618         struct device *dev;
 619         struct rtc_device *rtc = NULL;
 620
 621         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 622         if (dev)
 623                 rtc = to_rtc_device(dev);
 624
 625         if (rtc) {
 626                 if (!try_module_get(rtc->owner)) {
 627                         put_device(dev);
 628                         rtc = NULL;
 629                 }
 630         }
 631
 632         return rtc;
 633 }
 634 EXPORT_SYMBOL_GPL(rtc_class_open);
 635
 636 void rtc_class_close(struct rtc_device *rtc)
 637 {
 638         module_put(rtc->owner);
 639         put_device(&rtc->dev);
 640 }
 641 EXPORT_SYMBOL_GPL(rtc_class_close);
 642
 643 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 644 {
 645         int retval = -EBUSY;
 646
 647         if (task == NULL || task->func == NULL)
 648                 return -EINVAL;
 649
 650         /* Cannot register while the char dev is in use */
 651         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 652                 return -EBUSY;
 653
 654         spin_lock_irq(&rtc->irq_task_lock);
 655         if (rtc->irq_task == NULL) {
 656                 rtc->irq_task = task;
 657                 retval = 0;
 658         }
 659         spin_unlock_irq(&rtc->irq_task_lock);
 660
 661         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 662
 663         return retval;
 664 }
 665 EXPORT_SYMBOL_GPL(rtc_irq_register);
 666
 667 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 668 {
 669         spin_lock_irq(&rtc->irq_task_lock);
 670         if (rtc->irq_task == task)
 671                 rtc->irq_task = NULL;
 672         spin_unlock_irq(&rtc->irq_task_lock);
 673 }
 674 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 675
 676 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 677 {
 678         /*
 679          * We always cancel the timer here first, because otherwise
 680          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 681          * when we manage to start the timer before the callback
 682          * returns HRTIMER_RESTART.
 683          *
 684          * We cannot use hrtimer_cancel() here as a running callback
 685          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 686          * would spin forever.
 687          */
 688         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 689                 return -1;
 690
 691         if (enabled) {
 692                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 693
 694                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 695         }
 696         return 0;
 697 }
 698
 699 /**
 700  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 701  * @rtc: the rtc device
 702  * @task: currently registered with rtc_irq_register()
 703  * @enabled: true to enable periodic IRQs
 704  * Context: any
 705  *
 706  * Note that rtc_irq_set_freq() should previously have been used to
 707  * specify the desired frequency of periodic IRQ task->func() callbacks.
 708  */
 709 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 710 {
 711         int err = 0;
 712         unsigned long flags;
 713
 714 retry:
 715         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 716         if (rtc->irq_task != NULL && task == NULL)
 717                 err = -EBUSY;
 718         else if (rtc->irq_task != task)
 719                 err = -EACCES;
 720         else {
 721                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 722                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 723                         cpu_relax();
 724                         goto retry;
 725                 }
 726                 rtc->pie_enabled = enabled;
 727         }
 728         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 729         return err;
 730 }
 731 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 732
 733 /**
 734  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 735  * @rtc: the rtc device
 736  * @task: currently registered with rtc_irq_register()
 737  * @freq: positive frequency with which task->func() will be called
 738  * Context: any
 739  *
 740  * Note that rtc_irq_set_state() is used to enable or disable the
 741  * periodic IRQs.
 742  */
 743 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 744 {
 745         int err = 0;
 746         unsigned long flags;
 747
 748         if (freq <= 0 || freq > RTC_MAX_FREQ)
 749                 return -EINVAL;
 750 retry:
 751         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 752         if (rtc->irq_task != NULL && task == NULL)
 753                 err = -EBUSY;
 754         else if (rtc->irq_task != task)
 755                 err = -EACCES;
 756         else {
 757                 rtc->irq_freq = freq;
 758                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 759                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 760                         cpu_relax();
 761                         goto retry;
 762                 }
 763         }
 764         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 765         return err;
 766 }
 767 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 768
 769 /**
 770  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 771  * @rtc rtc device
 772  * @timer timer being added.
 773  *
 774  * Enqueues a timer onto the rtc devices timerqueue and sets
 775  * the next alarm event appropriately.
 776  *
 777  * Sets the enabled bit on the added timer.
 778  *
 779  * Must hold ops_lock for proper serialization of timerqueue
 780  */
 781 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 782 {
 783         timer->enabled = 1;
 784         timerqueue_add(&rtc->timerqueue, &timer->node);
 785         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 786                 struct rtc_wkalrm alarm;
 787                 int err;
 788                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 789                 alarm.enabled = 1;
 790                 err = __rtc_set_alarm(rtc, &alarm);
 791                 if (err == -ETIME) {
 792                         pm_stay_awake(rtc->dev.parent);
 793                         schedule_work(&rtc->irqwork);
 794                 } else if (err) {
 795                         timerqueue_del(&rtc->timerqueue, &timer->node);
 796                         timer->enabled = 0;
 797                         return err;
 798                 }
 799         }
 800         return 0;
 801 }
 802
 803 static void rtc_alarm_disable(struct rtc_device *rtc)
 804 {
 805         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 806                 return;
 807
 808         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 809 }
 810
 811 /**
 812  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 813  * @rtc rtc device
 814  * @timer timer being removed.
 815  *
 816  * Removes a timer onto the rtc devices timerqueue and sets
 817  * the next alarm event appropriately.
 818  *
 819  * Clears the enabled bit on the removed timer.
 820  *
 821  * Must hold ops_lock for proper serialization of timerqueue
 822  */
 823 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 824 {
 825         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 826         timerqueue_del(&rtc->timerqueue, &timer->node);
 827         timer->enabled = 0;
 828         if (next == &timer->node) {
 829                 struct rtc_wkalrm alarm;
 830                 int err;
 831                 next = timerqueue_getnext(&rtc->timerqueue);
 832                 if (!next) {
 833                         rtc_alarm_disable(rtc);
 834                         return;
 835                 }
 836                 alarm.time = rtc_ktime_to_tm(next->expires);
 837                 alarm.enabled = 1;
 838                 err = __rtc_set_alarm(rtc, &alarm);
 839                 if (err == -ETIME) {
 840                         pm_stay_awake(rtc->dev.parent);
 841                         schedule_work(&rtc->irqwork);
 842                 }
 843         }
 844 }
 845
 846 /**
 847  * rtc_timer_do_work - Expires rtc timers
 848  * @rtc rtc device
 849  * @timer timer being removed.
 850  *
 851  * Expires rtc timers. Reprograms next alarm event if needed.
 852  * Called via worktask.
 853  *
 854  * Serializes access to timerqueue via ops_lock mutex
 855  */
 856 void rtc_timer_do_work(struct work_struct *work)
 857 {
 858         struct rtc_timer *timer;
 859         struct timerqueue_node *next;
 860         ktime_t now;
 861         struct rtc_time tm;
 862
 863         struct rtc_device *rtc =
 864                 container_of(work, struct rtc_device, irqwork);
 865
 866         mutex_lock(&rtc->ops_lock);
 867 again:
 868         __rtc_read_time(rtc, &tm);
 869         now = rtc_tm_to_ktime(tm);
 870         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 871                 if (next->expires.tv64 > now.tv64)
 872                         break;
 873
 874                 /* expire timer */
 875                 timer = container_of(next, struct rtc_timer, node);
 876                 timerqueue_del(&rtc->timerqueue, &timer->node);
 877                 timer->enabled = 0;
 878                 if (timer->task.func)
 879                         timer->task.func(timer->task.private_data);
 880
 881                 /* Re-add/fwd periodic timers */
 882                 if (ktime_to_ns(timer->period)) {
 883                         timer->node.expires = ktime_add(timer->node.expires,
 884                                                         timer->period);
 885                         timer->enabled = 1;
 886                         timerqueue_add(&rtc->timerqueue, &timer->node);
 887                 }
 888         }
 889
 890         /* Set next alarm */
 891         if (next) {
 892                 struct rtc_wkalrm alarm;
 893                 int err;
 894                 alarm.time = rtc_ktime_to_tm(next->expires);
 895                 alarm.enabled = 1;
 896                 err = __rtc_set_alarm(rtc, &alarm);
 897                 if (err == -ETIME)
 898                         goto again;
 899         } else
 900                 rtc_alarm_disable(rtc);
 901
 902         pm_relax(rtc->dev.parent);
 903         mutex_unlock(&rtc->ops_lock);
 904 }
 905
 906
 907 /* rtc_timer_init - Initializes an rtc_timer
 908  * @timer: timer to be intiialized
 909  * @f: function pointer to be called when timer fires
 910  * @data: private data passed to function pointer
 911  *
 912  * Kernel interface to initializing an rtc_timer.
 913  */
 914 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 915 {
 916         timerqueue_init(&timer->node);
 917         timer->enabled = 0;
 918         timer->task.func = f;
 919         timer->task.private_data = data;
 920 }
 921
 922 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 923  * @ rtc: rtc device to be used
 924  * @ timer: timer being set
 925  * @ expires: time at which to expire the timer
 926  * @ period: period that the timer will recur
 927  *
 928  * Kernel interface to set an rtc_timer
 929  */
 930 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 931                         ktime_t expires, ktime_t period)
 932 {
 933         int ret = 0;
 934         mutex_lock(&rtc->ops_lock);
 935         if (timer->enabled)
 936                 rtc_timer_remove(rtc, timer);
 937
 938         timer->node.expires = expires;
 939         timer->period = period;
 940
 941         ret = rtc_timer_enqueue(rtc, timer);
 942
 943         mutex_unlock(&rtc->ops_lock);
 944         return ret;
 945 }
 946
 947 /* rtc_timer_cancel - Stops an rtc_timer
 948  * @ rtc: rtc device to be used
 949  * @ timer: timer being set
 950  *
 951  * Kernel interface to cancel an rtc_timer
 952  */
 953 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 954 {
 955         int ret = 0;
 956         mutex_lock(&rtc->ops_lock);
 957         if (timer->enabled)
 958                 rtc_timer_remove(rtc, timer);
 959         mutex_unlock(&rtc->ops_lock);
 960         return ret;
 961 }
 962
 963