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         rtc_tm_to_time(&tm, &now);
 352         if (scheduled <= now)
 353                 return -ETIME;
 354         /*
 355          * XXX - We just checked to make sure the alarm time is not
 356          * in the past, but there is still a race window where if
 357          * the is alarm set for the next second and the second ticks
 358          * over right here, before we set the alarm.
 359          */
 360
 361         if (!rtc->ops)
 362                 err = -ENODEV;
 363         else if (!rtc->ops->set_alarm)
 364                 err = -EINVAL;
 365         else
 366                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 367
 368         return err;
 369 }
 370
 371 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 372 {
 373         int err;
 374
 375         err = rtc_valid_tm(&alarm->time);
 376         if (err != 0)
 377                 return err;
 378
 379         err = mutex_lock_interruptible(&rtc->ops_lock);
 380         if (err)
 381                 return err;
 382         if (rtc->aie_timer.enabled)
 383                 rtc_timer_remove(rtc, &rtc->aie_timer);
 384
 385         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 386         rtc->aie_timer.period = ktime_set(0, 0);
 387         if (alarm->enabled)
 388                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 389
 390         mutex_unlock(&rtc->ops_lock);
 391         return err;
 392 }
 393 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 394
 395 /* Called once per device from rtc_device_register */
 396 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 397 {
 398         int err;
 399         struct rtc_time now;
 400
 401         err = rtc_valid_tm(&alarm->time);
 402         if (err != 0)
 403                 return err;
 404
 405         err = rtc_read_time(rtc, &now);
 406         if (err)
 407                 return err;
 408
 409         err = mutex_lock_interruptible(&rtc->ops_lock);
 410         if (err)
 411                 return err;
 412
 413         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 414         rtc->aie_timer.period = ktime_set(0, 0);
 415
 416         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 417         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 418                          rtc->aie_timer.node.expires.tv64)) {
 419
 420                 rtc->aie_timer.enabled = 1;
 421                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 422         }
 423         mutex_unlock(&rtc->ops_lock);
 424         return err;
 425 }
 426 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 427
 428
 429
 430 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 431 {
 432         int err = mutex_lock_interruptible(&rtc->ops_lock);
 433         if (err)
 434                 return err;
 435
 436         if (rtc->aie_timer.enabled != enabled) {
 437                 if (enabled)
 438                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 439                 else
 440                         rtc_timer_remove(rtc, &rtc->aie_timer);
 441         }
 442
 443         if (err)
 444                 /* nothing */;
 445         else if (!rtc->ops)
 446                 err = -ENODEV;
 447         else if (!rtc->ops->alarm_irq_enable)
 448                 err = -EINVAL;
 449         else
 450                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 451
 452         mutex_unlock(&rtc->ops_lock);
 453         return err;
 454 }
 455 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 456
 457 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 458 {
 459         int err = mutex_lock_interruptible(&rtc->ops_lock);
 460         if (err)
 461                 return err;
 462
 463 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 464         if (enabled == 0 && rtc->uie_irq_active) {
 465                 mutex_unlock(&rtc->ops_lock);
 466                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 467         }
 468 #endif
 469         /* make sure we're changing state */
 470         if (rtc->uie_rtctimer.enabled == enabled)
 471                 goto out;
 472
 473         if (rtc->uie_unsupported) {
 474                 err = -EINVAL;
 475                 goto out;
 476         }
 477
 478         if (enabled) {
 479                 struct rtc_time tm;
 480                 ktime_t now, onesec;
 481
 482                 __rtc_read_time(rtc, &tm);
 483                 onesec = ktime_set(1, 0);
 484                 now = rtc_tm_to_ktime(tm);
 485                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 486                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 487                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 488         } else
 489                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 490
 491 out:
 492         mutex_unlock(&rtc->ops_lock);
 493 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 494         /*
 495          * Enable emulation if the driver did not provide
 496          * the update_irq_enable function pointer or if returned
 497          * -EINVAL to signal that it has been configured without
 498          * interrupts or that are not available at the moment.
 499          */
 500         if (err == -EINVAL)
 501                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 502 #endif
 503         return err;
 504
 505 }
 506 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 507
 508
 509 /**
 510  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 511  * @rtc: pointer to the rtc device
 512  *
 513  * This function is called when an AIE, UIE or PIE mode interrupt
 514  * has occurred (or been emulated).
 515  *
 516  * Triggers the registered irq_task function callback.
 517  */
 518 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 519 {
 520         unsigned long flags;
 521
 522         /* mark one irq of the appropriate mode */
 523         spin_lock_irqsave(&rtc->irq_lock, flags);
 524         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 525         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 526
 527         /* call the task func */
 528         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 529         if (rtc->irq_task)
 530                 rtc->irq_task->func(rtc->irq_task->private_data);
 531         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 532
 533         wake_up_interruptible(&rtc->irq_queue);
 534         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 535 }
 536
 537
 538 /**
 539  * rtc_aie_update_irq - AIE mode rtctimer hook
 540  * @private: pointer to the rtc_device
 541  *
 542  * This functions is called when the aie_timer expires.
 543  */
 544 void rtc_aie_update_irq(void *private)
 545 {
 546         struct rtc_device *rtc = (struct rtc_device *)private;
 547         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 548 }
 549
 550
 551 /**
 552  * rtc_uie_update_irq - UIE mode rtctimer hook
 553  * @private: pointer to the rtc_device
 554  *
 555  * This functions is called when the uie_timer expires.
 556  */
 557 void rtc_uie_update_irq(void *private)
 558 {
 559         struct rtc_device *rtc = (struct rtc_device *)private;
 560         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 561 }
 562
 563
 564 /**
 565  * rtc_pie_update_irq - PIE mode hrtimer hook
 566  * @timer: pointer to the pie mode hrtimer
 567  *
 568  * This function is used to emulate PIE mode interrupts
 569  * using an hrtimer. This function is called when the periodic
 570  * hrtimer expires.
 571  */
 572 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 573 {
 574         struct rtc_device *rtc;
 575         ktime_t period;
 576         int count;
 577         rtc = container_of(timer, struct rtc_device, pie_timer);
 578
 579         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 580         count = hrtimer_forward_now(timer, period);
 581
 582         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 583
 584         return HRTIMER_RESTART;
 585 }
 586
 587 /**
 588  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 589  * @rtc: the rtc device
 590  * @num: how many irqs are being reported (usually one)
 591  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 592  * Context: any
 593  */
 594 void rtc_update_irq(struct rtc_device *rtc,
 595                 unsigned long num, unsigned long events)
 596 {
 597         if (unlikely(IS_ERR_OR_NULL(rtc)))
 598                 return;
 599
 600         pm_stay_awake(rtc->dev.parent);
 601         schedule_work(&rtc->irqwork);
 602 }
 603 EXPORT_SYMBOL_GPL(rtc_update_irq);
 604
 605 static int __rtc_match(struct device *dev, const void *data)
 606 {
 607         const char *name = data;
 608
 609         if (strcmp(dev_name(dev), name) == 0)
 610                 return 1;
 611         return 0;
 612 }
 613
 614 struct rtc_device *rtc_class_open(const char *name)
 615 {
 616         struct device *dev;
 617         struct rtc_device *rtc = NULL;
 618
 619         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 620         if (dev)
 621                 rtc = to_rtc_device(dev);
 622
 623         if (rtc) {
 624                 if (!try_module_get(rtc->owner)) {
 625                         put_device(dev);
 626                         rtc = NULL;
 627                 }
 628         }
 629
 630         return rtc;
 631 }
 632 EXPORT_SYMBOL_GPL(rtc_class_open);
 633
 634 void rtc_class_close(struct rtc_device *rtc)
 635 {
 636         module_put(rtc->owner);
 637         put_device(&rtc->dev);
 638 }
 639 EXPORT_SYMBOL_GPL(rtc_class_close);
 640
 641 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 642 {
 643         int retval = -EBUSY;
 644
 645         if (task == NULL || task->func == NULL)
 646                 return -EINVAL;
 647
 648         /* Cannot register while the char dev is in use */
 649         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 650                 return -EBUSY;
 651
 652         spin_lock_irq(&rtc->irq_task_lock);
 653         if (rtc->irq_task == NULL) {
 654                 rtc->irq_task = task;
 655                 retval = 0;
 656         }
 657         spin_unlock_irq(&rtc->irq_task_lock);
 658
 659         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 660
 661         return retval;
 662 }
 663 EXPORT_SYMBOL_GPL(rtc_irq_register);
 664
 665 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 666 {
 667         spin_lock_irq(&rtc->irq_task_lock);
 668         if (rtc->irq_task == task)
 669                 rtc->irq_task = NULL;
 670         spin_unlock_irq(&rtc->irq_task_lock);
 671 }
 672 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 673
 674 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 675 {
 676         /*
 677          * We always cancel the timer here first, because otherwise
 678          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 679          * when we manage to start the timer before the callback
 680          * returns HRTIMER_RESTART.
 681          *
 682          * We cannot use hrtimer_cancel() here as a running callback
 683          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 684          * would spin forever.
 685          */
 686         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 687                 return -1;
 688
 689         if (enabled) {
 690                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 691
 692                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 693         }
 694         return 0;
 695 }
 696
 697 /**
 698  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 699  * @rtc: the rtc device
 700  * @task: currently registered with rtc_irq_register()
 701  * @enabled: true to enable periodic IRQs
 702  * Context: any
 703  *
 704  * Note that rtc_irq_set_freq() should previously have been used to
 705  * specify the desired frequency of periodic IRQ task->func() callbacks.
 706  */
 707 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 708 {
 709         int err = 0;
 710         unsigned long flags;
 711
 712 retry:
 713         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 714         if (rtc->irq_task != NULL && task == NULL)
 715                 err = -EBUSY;
 716         else if (rtc->irq_task != task)
 717                 err = -EACCES;
 718         else {
 719                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 720                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 721                         cpu_relax();
 722                         goto retry;
 723                 }
 724                 rtc->pie_enabled = enabled;
 725         }
 726         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 727         return err;
 728 }
 729 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 730
 731 /**
 732  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 733  * @rtc: the rtc device
 734  * @task: currently registered with rtc_irq_register()
 735  * @freq: positive frequency with which task->func() will be called
 736  * Context: any
 737  *
 738  * Note that rtc_irq_set_state() is used to enable or disable the
 739  * periodic IRQs.
 740  */
 741 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 742 {
 743         int err = 0;
 744         unsigned long flags;
 745
 746         if (freq <= 0 || freq > RTC_MAX_FREQ)
 747                 return -EINVAL;
 748 retry:
 749         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 750         if (rtc->irq_task != NULL && task == NULL)
 751                 err = -EBUSY;
 752         else if (rtc->irq_task != task)
 753                 err = -EACCES;
 754         else {
 755                 rtc->irq_freq = freq;
 756                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 757                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 758                         cpu_relax();
 759                         goto retry;
 760                 }
 761         }
 762         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 763         return err;
 764 }
 765 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 766
 767 /**
 768  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 769  * @rtc rtc device
 770  * @timer timer being added.
 771  *
 772  * Enqueues a timer onto the rtc devices timerqueue and sets
 773  * the next alarm event appropriately.
 774  *
 775  * Sets the enabled bit on the added timer.
 776  *
 777  * Must hold ops_lock for proper serialization of timerqueue
 778  */
 779 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 780 {
 781         timer->enabled = 1;
 782         timerqueue_add(&rtc->timerqueue, &timer->node);
 783         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 784                 struct rtc_wkalrm alarm;
 785                 int err;
 786                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 787                 alarm.enabled = 1;
 788                 err = __rtc_set_alarm(rtc, &alarm);
 789                 if (err == -ETIME) {
 790                         pm_stay_awake(rtc->dev.parent);
 791                         schedule_work(&rtc->irqwork);
 792                 } else if (err) {
 793                         timerqueue_del(&rtc->timerqueue, &timer->node);
 794                         timer->enabled = 0;
 795                         return err;
 796                 }
 797         }
 798         return 0;
 799 }
 800
 801 static void rtc_alarm_disable(struct rtc_device *rtc)
 802 {
 803         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 804                 return;
 805
 806         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 807 }
 808
 809 /**
 810  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 811  * @rtc rtc device
 812  * @timer timer being removed.
 813  *
 814  * Removes a timer onto the rtc devices timerqueue and sets
 815  * the next alarm event appropriately.
 816  *
 817  * Clears the enabled bit on the removed timer.
 818  *
 819  * Must hold ops_lock for proper serialization of timerqueue
 820  */
 821 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 822 {
 823         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 824         timerqueue_del(&rtc->timerqueue, &timer->node);
 825         timer->enabled = 0;
 826         if (next == &timer->node) {
 827                 struct rtc_wkalrm alarm;
 828                 int err;
 829                 next = timerqueue_getnext(&rtc->timerqueue);
 830                 if (!next) {
 831                         rtc_alarm_disable(rtc);
 832                         return;
 833                 }
 834                 alarm.time = rtc_ktime_to_tm(next->expires);
 835                 alarm.enabled = 1;
 836                 err = __rtc_set_alarm(rtc, &alarm);
 837                 if (err == -ETIME) {
 838                         pm_stay_awake(rtc->dev.parent);
 839                         schedule_work(&rtc->irqwork);
 840                 }
 841         }
 842 }
 843
 844 /**
 845  * rtc_timer_do_work - Expires rtc timers
 846  * @rtc rtc device
 847  * @timer timer being removed.
 848  *
 849  * Expires rtc timers. Reprograms next alarm event if needed.
 850  * Called via worktask.
 851  *
 852  * Serializes access to timerqueue via ops_lock mutex
 853  */
 854 void rtc_timer_do_work(struct work_struct *work)
 855 {
 856         struct rtc_timer *timer;
 857         struct timerqueue_node *next;
 858         ktime_t now;
 859         struct rtc_time tm;
 860
 861         struct rtc_device *rtc =
 862                 container_of(work, struct rtc_device, irqwork);
 863
 864         mutex_lock(&rtc->ops_lock);
 865 again:
 866         __rtc_read_time(rtc, &tm);
 867         now = rtc_tm_to_ktime(tm);
 868         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 869                 if (next->expires.tv64 > now.tv64)
 870                         break;
 871
 872                 /* expire timer */
 873                 timer = container_of(next, struct rtc_timer, node);
 874                 timerqueue_del(&rtc->timerqueue, &timer->node);
 875                 timer->enabled = 0;
 876                 if (timer->task.func)
 877                         timer->task.func(timer->task.private_data);
 878
 879                 /* Re-add/fwd periodic timers */
 880                 if (ktime_to_ns(timer->period)) {
 881                         timer->node.expires = ktime_add(timer->node.expires,
 882                                                         timer->period);
 883                         timer->enabled = 1;
 884                         timerqueue_add(&rtc->timerqueue, &timer->node);
 885                 }
 886         }
 887
 888         /* Set next alarm */
 889         if (next) {
 890                 struct rtc_wkalrm alarm;
 891                 int err;
 892                 alarm.time = rtc_ktime_to_tm(next->expires);
 893                 alarm.enabled = 1;
 894                 err = __rtc_set_alarm(rtc, &alarm);
 895                 if (err == -ETIME)
 896                         goto again;
 897         } else
 898                 rtc_alarm_disable(rtc);
 899
 900         pm_relax(rtc->dev.parent);
 901         mutex_unlock(&rtc->ops_lock);
 902 }
 903
 904
 905 /* rtc_timer_init - Initializes an rtc_timer
 906  * @timer: timer to be intiialized
 907  * @f: function pointer to be called when timer fires
 908  * @data: private data passed to function pointer
 909  *
 910  * Kernel interface to initializing an rtc_timer.
 911  */
 912 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 913 {
 914         timerqueue_init(&timer->node);
 915         timer->enabled = 0;
 916         timer->task.func = f;
 917         timer->task.private_data = data;
 918 }
 919
 920 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 921  * @ rtc: rtc device to be used
 922  * @ timer: timer being set
 923  * @ expires: time at which to expire the timer
 924  * @ period: period that the timer will recur
 925  *
 926  * Kernel interface to set an rtc_timer
 927  */
 928 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 929                         ktime_t expires, ktime_t period)
 930 {
 931         int ret = 0;
 932         mutex_lock(&rtc->ops_lock);
 933         if (timer->enabled)
 934                 rtc_timer_remove(rtc, timer);
 935
 936         timer->node.expires = expires;
 937         timer->period = period;
 938
 939         ret = rtc_timer_enqueue(rtc, timer);
 940
 941         mutex_unlock(&rtc->ops_lock);
 942         return ret;
 943 }
 944
 945 /* rtc_timer_cancel - Stops an rtc_timer
 946  * @ rtc: rtc device to be used
 947  * @ timer: timer being set
 948  *
 949  * Kernel interface to cancel an rtc_timer
 950  */
 951 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 952 {
 953         int ret = 0;
 954         mutex_lock(&rtc->ops_lock);
 955         if (timer->enabled)
 956                 rtc_timer_remove(rtc, timer);
 957         mutex_unlock(&rtc->ops_lock);
 958         return ret;
 959 }
 960
 961