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                 if (err < 0) {
  34                         dev_err(&rtc->dev, "read_time: fail to read\n");
  35                         return err;
  36                 }
  37
  38                 err = rtc_valid_tm(tm);
  39                 if (err < 0)
  40                         dev_err(&rtc->dev, "read_time: rtc_time isn't valid\n");
  41         }
  42         return err;
  43 }
  44
  45 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  46 {
  47         int err;
  48
  49         err = mutex_lock_interruptible(&rtc->ops_lock);
  50         if (err)
  51                 return err;
  52
  53         err = __rtc_read_time(rtc, tm);
  54         mutex_unlock(&rtc->ops_lock);
  55         return err;
  56 }
  57 EXPORT_SYMBOL_GPL(rtc_read_time);
  58
  59 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  60 {
  61         int err;
  62
  63         err = rtc_valid_tm(tm);
  64         if (err != 0)
  65                 return err;
  66
  67         err = mutex_lock_interruptible(&rtc->ops_lock);
  68         if (err)
  69                 return err;
  70
  71         if (!rtc->ops)
  72                 err = -ENODEV;
  73         else if (rtc->ops->set_time)
  74                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  75         else if (rtc->ops->set_mmss) {
  76                 unsigned long secs;
  77                 err = rtc_tm_to_time(tm, &secs);
  78                 if (err == 0)
  79                         err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  80         } else
  81                 err = -EINVAL;
  82
  83         pm_stay_awake(rtc->dev.parent);
  84         mutex_unlock(&rtc->ops_lock);
  85         /* A timer might have just expired */
  86         schedule_work(&rtc->irqwork);
  87         return err;
  88 }
  89 EXPORT_SYMBOL_GPL(rtc_set_time);
  90
  91 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  92 {
  93         int err;
  94
  95         err = mutex_lock_interruptible(&rtc->ops_lock);
  96         if (err)
  97                 return err;
  98
  99         if (!rtc->ops)
 100                 err = -ENODEV;
 101         else if (rtc->ops->set_mmss)
 102                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 103         else if (rtc->ops->read_time && rtc->ops->set_time) {
 104                 struct rtc_time new, old;
 105
 106                 err = rtc->ops->read_time(rtc->dev.parent, &old);
 107                 if (err == 0) {
 108                         rtc_time_to_tm(secs, &new);
 109
 110                         /*
 111                          * avoid writing when we're going to change the day of
 112                          * the month. We will retry in the next minute. This
 113                          * basically means that if the RTC must not drift
 114                          * by more than 1 minute in 11 minutes.
 115                          */
 116                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 117                                 (new.tm_hour == 23 && new.tm_min == 59)))
 118                                 err = rtc->ops->set_time(rtc->dev.parent,
 119                                                 &new);
 120                 }
 121         } else {
 122                 err = -EINVAL;
 123         }
 124
 125         pm_stay_awake(rtc->dev.parent);
 126         mutex_unlock(&rtc->ops_lock);
 127         /* A timer might have just expired */
 128         schedule_work(&rtc->irqwork);
 129
 130         return err;
 131 }
 132 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 133
 134 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 135 {
 136         int err;
 137
 138         err = mutex_lock_interruptible(&rtc->ops_lock);
 139         if (err)
 140                 return err;
 141
 142         if (rtc->ops == NULL)
 143                 err = -ENODEV;
 144         else if (!rtc->ops->read_alarm)
 145                 err = -EINVAL;
 146         else {
 147                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 148                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 149         }
 150
 151         mutex_unlock(&rtc->ops_lock);
 152         return err;
 153 }
 154
 155 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 156 {
 157         int err;
 158         struct rtc_time before, now;
 159         int first_time = 1;
 160         unsigned long t_now, t_alm;
 161         enum { none, day, month, year } missing = none;
 162         unsigned days;
 163
 164         /* The lower level RTC driver may return -1 in some fields,
 165          * creating invalid alarm->time values, for reasons like:
 166          *
 167          *   - The hardware may not be capable of filling them in;
 168          *     many alarms match only on time-of-day fields, not
 169          *     day/month/year calendar data.
 170          *
 171          *   - Some hardware uses illegal values as "wildcard" match
 172          *     values, which non-Linux firmware (like a BIOS) may try
 173          *     to set up as e.g. "alarm 15 minutes after each hour".
 174          *     Linux uses only oneshot alarms.
 175          *
 176          * When we see that here, we deal with it by using values from
 177          * a current RTC timestamp for any missing (-1) values.  The
 178          * RTC driver prevents "periodic alarm" modes.
 179          *
 180          * But this can be racey, because some fields of the RTC timestamp
 181          * may have wrapped in the interval since we read the RTC alarm,
 182          * which would lead to us inserting inconsistent values in place
 183          * of the -1 fields.
 184          *
 185          * Reading the alarm and timestamp in the reverse sequence
 186          * would have the same race condition, and not solve the issue.
 187          *
 188          * So, we must first read the RTC timestamp,
 189          * then read the RTC alarm value,
 190          * and then read a second RTC timestamp.
 191          *
 192          * If any fields of the second timestamp have changed
 193          * when compared with the first timestamp, then we know
 194          * our timestamp may be inconsistent with that used by
 195          * the low-level rtc_read_alarm_internal() function.
 196          *
 197          * So, when the two timestamps disagree, we just loop and do
 198          * the process again to get a fully consistent set of values.
 199          *
 200          * This could all instead be done in the lower level driver,
 201          * but since more than one lower level RTC implementation needs it,
 202          * then it's probably best best to do it here instead of there..
 203          */
 204
 205         /* Get the "before" timestamp */
 206         err = rtc_read_time(rtc, &before);
 207         if (err < 0)
 208                 return err;
 209         do {
 210                 if (!first_time)
 211                         memcpy(&before, &now, sizeof(struct rtc_time));
 212                 first_time = 0;
 213
 214                 /* get the RTC alarm values, which may be incomplete */
 215                 err = rtc_read_alarm_internal(rtc, alarm);
 216                 if (err)
 217                         return err;
 218
 219                 /* full-function RTCs won't have such missing fields */
 220                 if (rtc_valid_tm(&alarm->time) == 0)
 221                         return 0;
 222
 223                 /* get the "after" timestamp, to detect wrapped fields */
 224                 err = rtc_read_time(rtc, &now);
 225                 if (err < 0)
 226                         return err;
 227
 228                 /* note that tm_sec is a "don't care" value here: */
 229         } while (   before.tm_min   != now.tm_min
 230                  || before.tm_hour  != now.tm_hour
 231                  || before.tm_mon   != now.tm_mon
 232                  || before.tm_year  != now.tm_year);
 233
 234         /* Fill in the missing alarm fields using the timestamp; we
 235          * know there's at least one since alarm->time is invalid.
 236          */
 237         if (alarm->time.tm_sec == -1)
 238                 alarm->time.tm_sec = now.tm_sec;
 239         if (alarm->time.tm_min == -1)
 240                 alarm->time.tm_min = now.tm_min;
 241         if (alarm->time.tm_hour == -1)
 242                 alarm->time.tm_hour = now.tm_hour;
 243
 244         /* For simplicity, only support date rollover for now */
 245         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 246                 alarm->time.tm_mday = now.tm_mday;
 247                 missing = day;
 248         }
 249         if ((unsigned)alarm->time.tm_mon >= 12) {
 250                 alarm->time.tm_mon = now.tm_mon;
 251                 if (missing == none)
 252                         missing = month;
 253         }
 254         if (alarm->time.tm_year == -1) {
 255                 alarm->time.tm_year = now.tm_year;
 256                 if (missing == none)
 257                         missing = year;
 258         }
 259
 260         /* with luck, no rollover is needed */
 261         rtc_tm_to_time(&now, &t_now);
 262         rtc_tm_to_time(&alarm->time, &t_alm);
 263         if (t_now < t_alm)
 264                 goto done;
 265
 266         switch (missing) {
 267
 268         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 269          * that will trigger at 5am will do so at 5am Tuesday, which
 270          * could also be in the next month or year.  This is a common
 271          * case, especially for PCs.
 272          */
 273         case day:
 274                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 275                 t_alm += 24 * 60 * 60;
 276                 rtc_time_to_tm(t_alm, &alarm->time);
 277                 break;
 278
 279         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 280          * be next month.  An alarm matching on the 30th, 29th, or 28th
 281          * may end up in the month after that!  Many newer PCs support
 282          * this type of alarm.
 283          */
 284         case month:
 285                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 286                 do {
 287                         if (alarm->time.tm_mon < 11)
 288                                 alarm->time.tm_mon++;
 289                         else {
 290                                 alarm->time.tm_mon = 0;
 291                                 alarm->time.tm_year++;
 292                         }
 293                         days = rtc_month_days(alarm->time.tm_mon,
 294                                         alarm->time.tm_year);
 295                 } while (days < alarm->time.tm_mday);
 296                 break;
 297
 298         /* Year rollover ... easy except for leap years! */
 299         case year:
 300                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 301                 do {
 302                         alarm->time.tm_year++;
 303                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 304                         && rtc_valid_tm(&alarm->time) != 0);
 305                 break;
 306
 307         default:
 308                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 309         }
 310
 311 done:
 312         err = rtc_valid_tm(&alarm->time);
 313
 314         if (err) {
 315                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 316                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 317                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 318                         alarm->time.tm_sec);
 319         }
 320
 321         return err;
 322 }
 323
 324 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 325 {
 326         int err;
 327
 328         err = mutex_lock_interruptible(&rtc->ops_lock);
 329         if (err)
 330                 return err;
 331         if (rtc->ops == NULL)
 332                 err = -ENODEV;
 333         else if (!rtc->ops->read_alarm)
 334                 err = -EINVAL;
 335         else {
 336                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 337                 alarm->enabled = rtc->aie_timer.enabled;
 338                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 339         }
 340         mutex_unlock(&rtc->ops_lock);
 341
 342         return err;
 343 }
 344 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 345
 346 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 347 {
 348         struct rtc_time tm;
 349         long now, scheduled;
 350         int err;
 351
 352         err = rtc_valid_tm(&alarm->time);
 353         if (err)
 354                 return err;
 355         rtc_tm_to_time(&alarm->time, &scheduled);
 356
 357         /* Make sure we're not setting alarms in the past */
 358         err = __rtc_read_time(rtc, &tm);
 359         if (err)
 360                 return err;
 361         rtc_tm_to_time(&tm, &now);
 362         if (scheduled <= now)
 363                 return -ETIME;
 364         /*
 365          * XXX - We just checked to make sure the alarm time is not
 366          * in the past, but there is still a race window where if
 367          * the is alarm set for the next second and the second ticks
 368          * over right here, before we set the alarm.
 369          */
 370
 371         if (!rtc->ops)
 372                 err = -ENODEV;
 373         else if (!rtc->ops->set_alarm)
 374                 err = -EINVAL;
 375         else
 376                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 377
 378         return err;
 379 }
 380
 381 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 382 {
 383         int err;
 384
 385         err = rtc_valid_tm(&alarm->time);
 386         if (err != 0)
 387                 return err;
 388
 389         err = mutex_lock_interruptible(&rtc->ops_lock);
 390         if (err)
 391                 return err;
 392         if (rtc->aie_timer.enabled)
 393                 rtc_timer_remove(rtc, &rtc->aie_timer);
 394
 395         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 396         rtc->aie_timer.period = ktime_set(0, 0);
 397         if (alarm->enabled)
 398                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 399
 400         mutex_unlock(&rtc->ops_lock);
 401         return err;
 402 }
 403 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 404
 405 /* Called once per device from rtc_device_register */
 406 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 407 {
 408         int err;
 409         struct rtc_time now;
 410
 411         err = rtc_valid_tm(&alarm->time);
 412         if (err != 0)
 413                 return err;
 414
 415         err = rtc_read_time(rtc, &now);
 416         if (err)
 417                 return err;
 418
 419         err = mutex_lock_interruptible(&rtc->ops_lock);
 420         if (err)
 421                 return err;
 422
 423         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 424         rtc->aie_timer.period = ktime_set(0, 0);
 425
 426         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 427         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 428                          rtc->aie_timer.node.expires.tv64)) {
 429
 430                 rtc->aie_timer.enabled = 1;
 431                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 432         }
 433         mutex_unlock(&rtc->ops_lock);
 434         return err;
 435 }
 436 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 437
 438
 439
 440 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 441 {
 442         int err = mutex_lock_interruptible(&rtc->ops_lock);
 443         if (err)
 444                 return err;
 445
 446         if (rtc->aie_timer.enabled != enabled) {
 447                 if (enabled)
 448                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 449                 else
 450                         rtc_timer_remove(rtc, &rtc->aie_timer);
 451         }
 452
 453         if (err)
 454                 /* nothing */;
 455         else if (!rtc->ops)
 456                 err = -ENODEV;
 457         else if (!rtc->ops->alarm_irq_enable)
 458                 err = -EINVAL;
 459         else
 460                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 461
 462         mutex_unlock(&rtc->ops_lock);
 463         return err;
 464 }
 465 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 466
 467 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 468 {
 469         int err = mutex_lock_interruptible(&rtc->ops_lock);
 470         if (err)
 471                 return err;
 472
 473 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 474         if (enabled == 0 && rtc->uie_irq_active) {
 475                 mutex_unlock(&rtc->ops_lock);
 476                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 477         }
 478 #endif
 479         /* make sure we're changing state */
 480         if (rtc->uie_rtctimer.enabled == enabled)
 481                 goto out;
 482
 483         if (rtc->uie_unsupported) {
 484                 err = -EINVAL;
 485                 goto out;
 486         }
 487
 488         if (enabled) {
 489                 struct rtc_time tm;
 490                 ktime_t now, onesec;
 491
 492                 __rtc_read_time(rtc, &tm);
 493                 onesec = ktime_set(1, 0);
 494                 now = rtc_tm_to_ktime(tm);
 495                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 496                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 497                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 498         } else
 499                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 500
 501 out:
 502         mutex_unlock(&rtc->ops_lock);
 503 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 504         /*
 505          * Enable emulation if the driver did not provide
 506          * the update_irq_enable function pointer or if returned
 507          * -EINVAL to signal that it has been configured without
 508          * interrupts or that are not available at the moment.
 509          */
 510         if (err == -EINVAL)
 511                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 512 #endif
 513         return err;
 514
 515 }
 516 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 517
 518
 519 /**
 520  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 521  * @rtc: pointer to the rtc device
 522  *
 523  * This function is called when an AIE, UIE or PIE mode interrupt
 524  * has occurred (or been emulated).
 525  *
 526  * Triggers the registered irq_task function callback.
 527  */
 528 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 529 {
 530         unsigned long flags;
 531
 532         /* mark one irq of the appropriate mode */
 533         spin_lock_irqsave(&rtc->irq_lock, flags);
 534         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 535         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 536
 537         /* call the task func */
 538         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 539         if (rtc->irq_task)
 540                 rtc->irq_task->func(rtc->irq_task->private_data);
 541         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 542
 543         wake_up_interruptible(&rtc->irq_queue);
 544         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 545 }
 546
 547
 548 /**
 549  * rtc_aie_update_irq - AIE mode rtctimer hook
 550  * @private: pointer to the rtc_device
 551  *
 552  * This functions is called when the aie_timer expires.
 553  */
 554 void rtc_aie_update_irq(void *private)
 555 {
 556         struct rtc_device *rtc = (struct rtc_device *)private;
 557         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 558 }
 559
 560
 561 /**
 562  * rtc_uie_update_irq - UIE mode rtctimer hook
 563  * @private: pointer to the rtc_device
 564  *
 565  * This functions is called when the uie_timer expires.
 566  */
 567 void rtc_uie_update_irq(void *private)
 568 {
 569         struct rtc_device *rtc = (struct rtc_device *)private;
 570         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 571 }
 572
 573
 574 /**
 575  * rtc_pie_update_irq - PIE mode hrtimer hook
 576  * @timer: pointer to the pie mode hrtimer
 577  *
 578  * This function is used to emulate PIE mode interrupts
 579  * using an hrtimer. This function is called when the periodic
 580  * hrtimer expires.
 581  */
 582 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 583 {
 584         struct rtc_device *rtc;
 585         ktime_t period;
 586         int count;
 587         rtc = container_of(timer, struct rtc_device, pie_timer);
 588
 589         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 590         count = hrtimer_forward_now(timer, period);
 591
 592         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 593
 594         return HRTIMER_RESTART;
 595 }
 596
 597 /**
 598  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 599  * @rtc: the rtc device
 600  * @num: how many irqs are being reported (usually one)
 601  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 602  * Context: any
 603  */
 604 void rtc_update_irq(struct rtc_device *rtc,
 605                 unsigned long num, unsigned long events)
 606 {
 607         if (unlikely(IS_ERR_OR_NULL(rtc)))
 608                 return;
 609
 610         pm_stay_awake(rtc->dev.parent);
 611         schedule_work(&rtc->irqwork);
 612 }
 613 EXPORT_SYMBOL_GPL(rtc_update_irq);
 614
 615 static int __rtc_match(struct device *dev, const void *data)
 616 {
 617         const char *name = data;
 618
 619         if (strcmp(dev_name(dev), name) == 0)
 620                 return 1;
 621         return 0;
 622 }
 623
 624 struct rtc_device *rtc_class_open(const char *name)
 625 {
 626         struct device *dev;
 627         struct rtc_device *rtc = NULL;
 628
 629         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 630         if (dev)
 631                 rtc = to_rtc_device(dev);
 632
 633         if (rtc) {
 634                 if (!try_module_get(rtc->owner)) {
 635                         put_device(dev);
 636                         rtc = NULL;
 637                 }
 638         }
 639
 640         return rtc;
 641 }
 642 EXPORT_SYMBOL_GPL(rtc_class_open);
 643
 644 void rtc_class_close(struct rtc_device *rtc)
 645 {
 646         module_put(rtc->owner);
 647         put_device(&rtc->dev);
 648 }
 649 EXPORT_SYMBOL_GPL(rtc_class_close);
 650
 651 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 652 {
 653         int retval = -EBUSY;
 654
 655         if (task == NULL || task->func == NULL)
 656                 return -EINVAL;
 657
 658         /* Cannot register while the char dev is in use */
 659         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 660                 return -EBUSY;
 661
 662         spin_lock_irq(&rtc->irq_task_lock);
 663         if (rtc->irq_task == NULL) {
 664                 rtc->irq_task = task;
 665                 retval = 0;
 666         }
 667         spin_unlock_irq(&rtc->irq_task_lock);
 668
 669         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 670
 671         return retval;
 672 }
 673 EXPORT_SYMBOL_GPL(rtc_irq_register);
 674
 675 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 676 {
 677         spin_lock_irq(&rtc->irq_task_lock);
 678         if (rtc->irq_task == task)
 679                 rtc->irq_task = NULL;
 680         spin_unlock_irq(&rtc->irq_task_lock);
 681 }
 682 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 683
 684 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 685 {
 686         /*
 687          * We always cancel the timer here first, because otherwise
 688          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 689          * when we manage to start the timer before the callback
 690          * returns HRTIMER_RESTART.
 691          *
 692          * We cannot use hrtimer_cancel() here as a running callback
 693          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 694          * would spin forever.
 695          */
 696         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 697                 return -1;
 698
 699         if (enabled) {
 700                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 701
 702                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 703         }
 704         return 0;
 705 }
 706
 707 /**
 708  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 709  * @rtc: the rtc device
 710  * @task: currently registered with rtc_irq_register()
 711  * @enabled: true to enable periodic IRQs
 712  * Context: any
 713  *
 714  * Note that rtc_irq_set_freq() should previously have been used to
 715  * specify the desired frequency of periodic IRQ task->func() callbacks.
 716  */
 717 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 718 {
 719         int err = 0;
 720         unsigned long flags;
 721
 722 retry:
 723         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 724         if (rtc->irq_task != NULL && task == NULL)
 725                 err = -EBUSY;
 726         else if (rtc->irq_task != task)
 727                 err = -EACCES;
 728         else {
 729                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 730                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 731                         cpu_relax();
 732                         goto retry;
 733                 }
 734                 rtc->pie_enabled = enabled;
 735         }
 736         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 737         return err;
 738 }
 739 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 740
 741 /**
 742  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 743  * @rtc: the rtc device
 744  * @task: currently registered with rtc_irq_register()
 745  * @freq: positive frequency with which task->func() will be called
 746  * Context: any
 747  *
 748  * Note that rtc_irq_set_state() is used to enable or disable the
 749  * periodic IRQs.
 750  */
 751 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 752 {
 753         int err = 0;
 754         unsigned long flags;
 755
 756         if (freq <= 0 || freq > RTC_MAX_FREQ)
 757                 return -EINVAL;
 758 retry:
 759         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 760         if (rtc->irq_task != NULL && task == NULL)
 761                 err = -EBUSY;
 762         else if (rtc->irq_task != task)
 763                 err = -EACCES;
 764         else {
 765                 rtc->irq_freq = freq;
 766                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 767                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 768                         cpu_relax();
 769                         goto retry;
 770                 }
 771         }
 772         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 773         return err;
 774 }
 775 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 776
 777 /**
 778  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 779  * @rtc rtc device
 780  * @timer timer being added.
 781  *
 782  * Enqueues a timer onto the rtc devices timerqueue and sets
 783  * the next alarm event appropriately.
 784  *
 785  * Sets the enabled bit on the added timer.
 786  *
 787  * Must hold ops_lock for proper serialization of timerqueue
 788  */
 789 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 790 {
 791         timer->enabled = 1;
 792         timerqueue_add(&rtc->timerqueue, &timer->node);
 793         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 794                 struct rtc_wkalrm alarm;
 795                 int err;
 796                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 797                 alarm.enabled = 1;
 798                 err = __rtc_set_alarm(rtc, &alarm);
 799                 if (err == -ETIME) {
 800                         pm_stay_awake(rtc->dev.parent);
 801                         schedule_work(&rtc->irqwork);
 802                 } else if (err) {
 803                         timerqueue_del(&rtc->timerqueue, &timer->node);
 804                         timer->enabled = 0;
 805                         return err;
 806                 }
 807         }
 808         return 0;
 809 }
 810
 811 static void rtc_alarm_disable(struct rtc_device *rtc)
 812 {
 813         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 814                 return;
 815
 816         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 817 }
 818
 819 /**
 820  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 821  * @rtc rtc device
 822  * @timer timer being removed.
 823  *
 824  * Removes a timer onto the rtc devices timerqueue and sets
 825  * the next alarm event appropriately.
 826  *
 827  * Clears the enabled bit on the removed timer.
 828  *
 829  * Must hold ops_lock for proper serialization of timerqueue
 830  */
 831 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 832 {
 833         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 834         timerqueue_del(&rtc->timerqueue, &timer->node);
 835         timer->enabled = 0;
 836         if (next == &timer->node) {
 837                 struct rtc_wkalrm alarm;
 838                 int err;
 839                 next = timerqueue_getnext(&rtc->timerqueue);
 840                 if (!next) {
 841                         rtc_alarm_disable(rtc);
 842                         return;
 843                 }
 844                 alarm.time = rtc_ktime_to_tm(next->expires);
 845                 alarm.enabled = 1;
 846                 err = __rtc_set_alarm(rtc, &alarm);
 847                 if (err == -ETIME) {
 848                         pm_stay_awake(rtc->dev.parent);
 849                         schedule_work(&rtc->irqwork);
 850                 }
 851         }
 852 }
 853
 854 /**
 855  * rtc_timer_do_work - Expires rtc timers
 856  * @rtc rtc device
 857  * @timer timer being removed.
 858  *
 859  * Expires rtc timers. Reprograms next alarm event if needed.
 860  * Called via worktask.
 861  *
 862  * Serializes access to timerqueue via ops_lock mutex
 863  */
 864 void rtc_timer_do_work(struct work_struct *work)
 865 {
 866         struct rtc_timer *timer;
 867         struct timerqueue_node *next;
 868         ktime_t now;
 869         struct rtc_time tm;
 870
 871         struct rtc_device *rtc =
 872                 container_of(work, struct rtc_device, irqwork);
 873
 874         mutex_lock(&rtc->ops_lock);
 875 again:
 876         __rtc_read_time(rtc, &tm);
 877         now = rtc_tm_to_ktime(tm);
 878         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 879                 if (next->expires.tv64 > now.tv64)
 880                         break;
 881
 882                 /* expire timer */
 883                 timer = container_of(next, struct rtc_timer, node);
 884                 timerqueue_del(&rtc->timerqueue, &timer->node);
 885                 timer->enabled = 0;
 886                 if (timer->task.func)
 887                         timer->task.func(timer->task.private_data);
 888
 889                 /* Re-add/fwd periodic timers */
 890                 if (ktime_to_ns(timer->period)) {
 891                         timer->node.expires = ktime_add(timer->node.expires,
 892                                                         timer->period);
 893                         timer->enabled = 1;
 894                         timerqueue_add(&rtc->timerqueue, &timer->node);
 895                 }
 896         }
 897
 898         /* Set next alarm */
 899         if (next) {
 900                 struct rtc_wkalrm alarm;
 901                 int err;
 902                 int retry = 3;
 903
 904                 alarm.time = rtc_ktime_to_tm(next->expires);
 905                 alarm.enabled = 1;
 906 reprogram:
 907                 err = __rtc_set_alarm(rtc, &alarm);
 908                 if (err == -ETIME)
 909                         goto again;
 910                 else if (err) {
 911                         if (retry-- > 0)
 912                                 goto reprogram;
 913
 914                         timer = container_of(next, struct rtc_timer, node);
 915                         timerqueue_del(&rtc->timerqueue, &timer->node);
 916                         timer->enabled = 0;
 917                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 918                         goto again;
 919                 }
 920         } else
 921                 rtc_alarm_disable(rtc);
 922
 923         pm_relax(rtc->dev.parent);
 924         mutex_unlock(&rtc->ops_lock);
 925 }
 926
 927
 928 /* rtc_timer_init - Initializes an rtc_timer
 929  * @timer: timer to be intiialized
 930  * @f: function pointer to be called when timer fires
 931  * @data: private data passed to function pointer
 932  *
 933  * Kernel interface to initializing an rtc_timer.
 934  */
 935 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 936 {
 937         timerqueue_init(&timer->node);
 938         timer->enabled = 0;
 939         timer->task.func = f;
 940         timer->task.private_data = data;
 941 }
 942
 943 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 944  * @ rtc: rtc device to be used
 945  * @ timer: timer being set
 946  * @ expires: time at which to expire the timer
 947  * @ period: period that the timer will recur
 948  *
 949  * Kernel interface to set an rtc_timer
 950  */
 951 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 952                         ktime_t expires, ktime_t period)
 953 {
 954         int ret = 0;
 955         mutex_lock(&rtc->ops_lock);
 956         if (timer->enabled)
 957                 rtc_timer_remove(rtc, timer);
 958
 959         timer->node.expires = expires;
 960         timer->period = period;
 961
 962         ret = rtc_timer_enqueue(rtc, timer);
 963
 964         mutex_unlock(&rtc->ops_lock);
 965         return ret;
 966 }
 967
 968 /* rtc_timer_cancel - Stops an rtc_timer
 969  * @ rtc: rtc device to be used
 970  * @ timer: timer being set
 971  *
 972  * Kernel interface to cancel an rtc_timer
 973  */
 974 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 975 {
 976         int ret = 0;
 977         mutex_lock(&rtc->ops_lock);
 978         if (timer->enabled)
 979                 rtc_timer_remove(rtc, timer);
 980         mutex_unlock(&rtc->ops_lock);
 981         return ret;
 982 }
 983
 984