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                 time64_t secs64 = rtc_tm_to_time64(tm);
  77                 err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
  78         } else
  79                 err = -EINVAL;
  80
  81         pm_stay_awake(rtc->dev.parent);
  82         mutex_unlock(&rtc->ops_lock);
  83         /* A timer might have just expired */
  84         schedule_work(&rtc->irqwork);
  85         return err;
  86 }
  87 EXPORT_SYMBOL_GPL(rtc_set_time);
  88
  89 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  90 {
  91         int err;
  92
  93         err = mutex_lock_interruptible(&rtc->ops_lock);
  94         if (err)
  95                 return err;
  96
  97         if (!rtc->ops)
  98                 err = -ENODEV;
  99         else if (rtc->ops->set_mmss)
 100                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 101         else if (rtc->ops->read_time && rtc->ops->set_time) {
 102                 struct rtc_time new, old;
 103
 104                 err = rtc->ops->read_time(rtc->dev.parent, &old);
 105                 if (err == 0) {
 106                         rtc_time64_to_tm(secs, &new);
 107
 108                         /*
 109                          * avoid writing when we're going to change the day of
 110                          * the month. We will retry in the next minute. This
 111                          * basically means that if the RTC must not drift
 112                          * by more than 1 minute in 11 minutes.
 113                          */
 114                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 115                                 (new.tm_hour == 23 && new.tm_min == 59)))
 116                                 err = rtc->ops->set_time(rtc->dev.parent,
 117                                                 &new);
 118                 }
 119         } else {
 120                 err = -EINVAL;
 121         }
 122
 123         pm_stay_awake(rtc->dev.parent);
 124         mutex_unlock(&rtc->ops_lock);
 125         /* A timer might have just expired */
 126         schedule_work(&rtc->irqwork);
 127
 128         return err;
 129 }
 130 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 131
 132 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 133 {
 134         int err;
 135
 136         err = mutex_lock_interruptible(&rtc->ops_lock);
 137         if (err)
 138                 return err;
 139
 140         if (rtc->ops == NULL)
 141                 err = -ENODEV;
 142         else if (!rtc->ops->read_alarm)
 143                 err = -EINVAL;
 144         else {
 145                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 146                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 147         }
 148
 149         mutex_unlock(&rtc->ops_lock);
 150         return err;
 151 }
 152
 153 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 154 {
 155         int err;
 156         struct rtc_time before, now;
 157         int first_time = 1;
 158         time64_t t_now, t_alm;
 159         enum { none, day, month, year } missing = none;
 160         unsigned days;
 161
 162         /* The lower level RTC driver may return -1 in some fields,
 163          * creating invalid alarm->time values, for reasons like:
 164          *
 165          *   - The hardware may not be capable of filling them in;
 166          *     many alarms match only on time-of-day fields, not
 167          *     day/month/year calendar data.
 168          *
 169          *   - Some hardware uses illegal values as "wildcard" match
 170          *     values, which non-Linux firmware (like a BIOS) may try
 171          *     to set up as e.g. "alarm 15 minutes after each hour".
 172          *     Linux uses only oneshot alarms.
 173          *
 174          * When we see that here, we deal with it by using values from
 175          * a current RTC timestamp for any missing (-1) values.  The
 176          * RTC driver prevents "periodic alarm" modes.
 177          *
 178          * But this can be racey, because some fields of the RTC timestamp
 179          * may have wrapped in the interval since we read the RTC alarm,
 180          * which would lead to us inserting inconsistent values in place
 181          * of the -1 fields.
 182          *
 183          * Reading the alarm and timestamp in the reverse sequence
 184          * would have the same race condition, and not solve the issue.
 185          *
 186          * So, we must first read the RTC timestamp,
 187          * then read the RTC alarm value,
 188          * and then read a second RTC timestamp.
 189          *
 190          * If any fields of the second timestamp have changed
 191          * when compared with the first timestamp, then we know
 192          * our timestamp may be inconsistent with that used by
 193          * the low-level rtc_read_alarm_internal() function.
 194          *
 195          * So, when the two timestamps disagree, we just loop and do
 196          * the process again to get a fully consistent set of values.
 197          *
 198          * This could all instead be done in the lower level driver,
 199          * but since more than one lower level RTC implementation needs it,
 200          * then it's probably best best to do it here instead of there..
 201          */
 202
 203         /* Get the "before" timestamp */
 204         err = rtc_read_time(rtc, &before);
 205         if (err < 0)
 206                 return err;
 207         do {
 208                 if (!first_time)
 209                         memcpy(&before, &now, sizeof(struct rtc_time));
 210                 first_time = 0;
 211
 212                 /* get the RTC alarm values, which may be incomplete */
 213                 err = rtc_read_alarm_internal(rtc, alarm);
 214                 if (err)
 215                         return err;
 216
 217                 /* full-function RTCs won't have such missing fields */
 218                 if (rtc_valid_tm(&alarm->time) == 0)
 219                         return 0;
 220
 221                 /* get the "after" timestamp, to detect wrapped fields */
 222                 err = rtc_read_time(rtc, &now);
 223                 if (err < 0)
 224                         return err;
 225
 226                 /* note that tm_sec is a "don't care" value here: */
 227         } while (   before.tm_min   != now.tm_min
 228                  || before.tm_hour  != now.tm_hour
 229                  || before.tm_mon   != now.tm_mon
 230                  || before.tm_year  != now.tm_year);
 231
 232         /* Fill in the missing alarm fields using the timestamp; we
 233          * know there's at least one since alarm->time is invalid.
 234          */
 235         if (alarm->time.tm_sec == -1)
 236                 alarm->time.tm_sec = now.tm_sec;
 237         if (alarm->time.tm_min == -1)
 238                 alarm->time.tm_min = now.tm_min;
 239         if (alarm->time.tm_hour == -1)
 240                 alarm->time.tm_hour = now.tm_hour;
 241
 242         /* For simplicity, only support date rollover for now */
 243         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 244                 alarm->time.tm_mday = now.tm_mday;
 245                 missing = day;
 246         }
 247         if ((unsigned)alarm->time.tm_mon >= 12) {
 248                 alarm->time.tm_mon = now.tm_mon;
 249                 if (missing == none)
 250                         missing = month;
 251         }
 252         if (alarm->time.tm_year == -1) {
 253                 alarm->time.tm_year = now.tm_year;
 254                 if (missing == none)
 255                         missing = year;
 256         }
 257
 258         /* with luck, no rollover is needed */
 259         t_now = rtc_tm_to_time64(&now);
 260         t_alm = rtc_tm_to_time64(&alarm->time);
 261         if (t_now < t_alm)
 262                 goto done;
 263
 264         switch (missing) {
 265
 266         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 267          * that will trigger at 5am will do so at 5am Tuesday, which
 268          * could also be in the next month or year.  This is a common
 269          * case, especially for PCs.
 270          */
 271         case day:
 272                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 273                 t_alm += 24 * 60 * 60;
 274                 rtc_time64_to_tm(t_alm, &alarm->time);
 275                 break;
 276
 277         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 278          * be next month.  An alarm matching on the 30th, 29th, or 28th
 279          * may end up in the month after that!  Many newer PCs support
 280          * this type of alarm.
 281          */
 282         case month:
 283                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 284                 do {
 285                         if (alarm->time.tm_mon < 11)
 286                                 alarm->time.tm_mon++;
 287                         else {
 288                                 alarm->time.tm_mon = 0;
 289                                 alarm->time.tm_year++;
 290                         }
 291                         days = rtc_month_days(alarm->time.tm_mon,
 292                                         alarm->time.tm_year);
 293                 } while (days < alarm->time.tm_mday);
 294                 break;
 295
 296         /* Year rollover ... easy except for leap years! */
 297         case year:
 298                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 299                 do {
 300                         alarm->time.tm_year++;
 301                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 302                         && rtc_valid_tm(&alarm->time) != 0);
 303                 break;
 304
 305         default:
 306                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 307         }
 308
 309 done:
 310         err = rtc_valid_tm(&alarm->time);
 311
 312         if (err) {
 313                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 314                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 315                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 316                         alarm->time.tm_sec);
 317         }
 318
 319         return err;
 320 }
 321
 322 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 323 {
 324         int err;
 325
 326         err = mutex_lock_interruptible(&rtc->ops_lock);
 327         if (err)
 328                 return err;
 329         if (rtc->ops == NULL)
 330                 err = -ENODEV;
 331         else if (!rtc->ops->read_alarm)
 332                 err = -EINVAL;
 333         else {
 334                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 335                 alarm->enabled = rtc->aie_timer.enabled;
 336                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 337         }
 338         mutex_unlock(&rtc->ops_lock);
 339
 340         return err;
 341 }
 342 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 343
 344 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 345 {
 346         struct rtc_time tm;
 347         time64_t now, scheduled;
 348         int err;
 349
 350         err = rtc_valid_tm(&alarm->time);
 351         if (err)
 352                 return err;
 353         scheduled = rtc_tm_to_time64(&alarm->time);
 354
 355         /* Make sure we're not setting alarms in the past */
 356         err = __rtc_read_time(rtc, &tm);
 357         if (err)
 358                 return err;
 359         now = rtc_tm_to_time64(&tm);
 360         if (scheduled <= now)
 361                 return -ETIME;
 362         /*
 363          * XXX - We just checked to make sure the alarm time is not
 364          * in the past, but there is still a race window where if
 365          * the is alarm set for the next second and the second ticks
 366          * over right here, before we set the alarm.
 367          */
 368
 369         if (!rtc->ops)
 370                 err = -ENODEV;
 371         else if (!rtc->ops->set_alarm)
 372                 err = -EINVAL;
 373         else
 374                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 375
 376         return err;
 377 }
 378
 379 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 380 {
 381         int err;
 382
 383         err = rtc_valid_tm(&alarm->time);
 384         if (err != 0)
 385                 return err;
 386
 387         err = mutex_lock_interruptible(&rtc->ops_lock);
 388         if (err)
 389                 return err;
 390         if (rtc->aie_timer.enabled)
 391                 rtc_timer_remove(rtc, &rtc->aie_timer);
 392
 393         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 394         rtc->aie_timer.period = ktime_set(0, 0);
 395         if (alarm->enabled)
 396                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 397
 398         mutex_unlock(&rtc->ops_lock);
 399         return err;
 400 }
 401 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 402
 403 /* Called once per device from rtc_device_register */
 404 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 405 {
 406         int err;
 407         struct rtc_time now;
 408
 409         err = rtc_valid_tm(&alarm->time);
 410         if (err != 0)
 411                 return err;
 412
 413         err = rtc_read_time(rtc, &now);
 414         if (err)
 415                 return err;
 416
 417         err = mutex_lock_interruptible(&rtc->ops_lock);
 418         if (err)
 419                 return err;
 420
 421         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 422         rtc->aie_timer.period = ktime_set(0, 0);
 423
 424         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 425         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 426                          rtc->aie_timer.node.expires.tv64)) {
 427
 428                 rtc->aie_timer.enabled = 1;
 429                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 430         }
 431         mutex_unlock(&rtc->ops_lock);
 432         return err;
 433 }
 434 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 435
 436
 437
 438 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 439 {
 440         int err = mutex_lock_interruptible(&rtc->ops_lock);
 441         if (err)
 442                 return err;
 443
 444         if (rtc->aie_timer.enabled != enabled) {
 445                 if (enabled)
 446                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 447                 else
 448                         rtc_timer_remove(rtc, &rtc->aie_timer);
 449         }
 450
 451         if (err)
 452                 /* nothing */;
 453         else if (!rtc->ops)
 454                 err = -ENODEV;
 455         else if (!rtc->ops->alarm_irq_enable)
 456                 err = -EINVAL;
 457         else
 458                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 459
 460         mutex_unlock(&rtc->ops_lock);
 461         return err;
 462 }
 463 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 464
 465 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 466 {
 467         int err = mutex_lock_interruptible(&rtc->ops_lock);
 468         if (err)
 469                 return err;
 470
 471 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 472         if (enabled == 0 && rtc->uie_irq_active) {
 473                 mutex_unlock(&rtc->ops_lock);
 474                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 475         }
 476 #endif
 477         /* make sure we're changing state */
 478         if (rtc->uie_rtctimer.enabled == enabled)
 479                 goto out;
 480
 481         if (rtc->uie_unsupported) {
 482                 err = -EINVAL;
 483                 goto out;
 484         }
 485
 486         if (enabled) {
 487                 struct rtc_time tm;
 488                 ktime_t now, onesec;
 489
 490                 __rtc_read_time(rtc, &tm);
 491                 onesec = ktime_set(1, 0);
 492                 now = rtc_tm_to_ktime(tm);
 493                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 494                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 495                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 496         } else
 497                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 498
 499 out:
 500         mutex_unlock(&rtc->ops_lock);
 501 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 502         /*
 503          * Enable emulation if the driver did not provide
 504          * the update_irq_enable function pointer or if returned
 505          * -EINVAL to signal that it has been configured without
 506          * interrupts or that are not available at the moment.
 507          */
 508         if (err == -EINVAL)
 509                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 510 #endif
 511         return err;
 512
 513 }
 514 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 515
 516
 517 /**
 518  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 519  * @rtc: pointer to the rtc device
 520  *
 521  * This function is called when an AIE, UIE or PIE mode interrupt
 522  * has occurred (or been emulated).
 523  *
 524  * Triggers the registered irq_task function callback.
 525  */
 526 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 527 {
 528         unsigned long flags;
 529
 530         /* mark one irq of the appropriate mode */
 531         spin_lock_irqsave(&rtc->irq_lock, flags);
 532         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 533         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 534
 535         /* call the task func */
 536         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 537         if (rtc->irq_task)
 538                 rtc->irq_task->func(rtc->irq_task->private_data);
 539         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 540
 541         wake_up_interruptible(&rtc->irq_queue);
 542         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 543 }
 544
 545
 546 /**
 547  * rtc_aie_update_irq - AIE mode rtctimer hook
 548  * @private: pointer to the rtc_device
 549  *
 550  * This functions is called when the aie_timer expires.
 551  */
 552 void rtc_aie_update_irq(void *private)
 553 {
 554         struct rtc_device *rtc = (struct rtc_device *)private;
 555         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 556 }
 557
 558
 559 /**
 560  * rtc_uie_update_irq - UIE mode rtctimer hook
 561  * @private: pointer to the rtc_device
 562  *
 563  * This functions is called when the uie_timer expires.
 564  */
 565 void rtc_uie_update_irq(void *private)
 566 {
 567         struct rtc_device *rtc = (struct rtc_device *)private;
 568         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 569 }
 570
 571
 572 /**
 573  * rtc_pie_update_irq - PIE mode hrtimer hook
 574  * @timer: pointer to the pie mode hrtimer
 575  *
 576  * This function is used to emulate PIE mode interrupts
 577  * using an hrtimer. This function is called when the periodic
 578  * hrtimer expires.
 579  */
 580 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 581 {
 582         struct rtc_device *rtc;
 583         ktime_t period;
 584         int count;
 585         rtc = container_of(timer, struct rtc_device, pie_timer);
 586
 587         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 588         count = hrtimer_forward_now(timer, period);
 589
 590         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 591
 592         return HRTIMER_RESTART;
 593 }
 594
 595 /**
 596  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 597  * @rtc: the rtc device
 598  * @num: how many irqs are being reported (usually one)
 599  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 600  * Context: any
 601  */
 602 void rtc_update_irq(struct rtc_device *rtc,
 603                 unsigned long num, unsigned long events)
 604 {
 605         if (unlikely(IS_ERR_OR_NULL(rtc)))
 606                 return;
 607
 608         pm_stay_awake(rtc->dev.parent);
 609         schedule_work(&rtc->irqwork);
 610 }
 611 EXPORT_SYMBOL_GPL(rtc_update_irq);
 612
 613 static int __rtc_match(struct device *dev, const void *data)
 614 {
 615         const char *name = data;
 616
 617         if (strcmp(dev_name(dev), name) == 0)
 618                 return 1;
 619         return 0;
 620 }
 621
 622 struct rtc_device *rtc_class_open(const char *name)
 623 {
 624         struct device *dev;
 625         struct rtc_device *rtc = NULL;
 626
 627         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 628         if (dev)
 629                 rtc = to_rtc_device(dev);
 630
 631         if (rtc) {
 632                 if (!try_module_get(rtc->owner)) {
 633                         put_device(dev);
 634                         rtc = NULL;
 635                 }
 636         }
 637
 638         return rtc;
 639 }
 640 EXPORT_SYMBOL_GPL(rtc_class_open);
 641
 642 void rtc_class_close(struct rtc_device *rtc)
 643 {
 644         module_put(rtc->owner);
 645         put_device(&rtc->dev);
 646 }
 647 EXPORT_SYMBOL_GPL(rtc_class_close);
 648
 649 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 650 {
 651         int retval = -EBUSY;
 652
 653         if (task == NULL || task->func == NULL)
 654                 return -EINVAL;
 655
 656         /* Cannot register while the char dev is in use */
 657         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 658                 return -EBUSY;
 659
 660         spin_lock_irq(&rtc->irq_task_lock);
 661         if (rtc->irq_task == NULL) {
 662                 rtc->irq_task = task;
 663                 retval = 0;
 664         }
 665         spin_unlock_irq(&rtc->irq_task_lock);
 666
 667         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 668
 669         return retval;
 670 }
 671 EXPORT_SYMBOL_GPL(rtc_irq_register);
 672
 673 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 674 {
 675         spin_lock_irq(&rtc->irq_task_lock);
 676         if (rtc->irq_task == task)
 677                 rtc->irq_task = NULL;
 678         spin_unlock_irq(&rtc->irq_task_lock);
 679 }
 680 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 681
 682 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 683 {
 684         /*
 685          * We always cancel the timer here first, because otherwise
 686          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 687          * when we manage to start the timer before the callback
 688          * returns HRTIMER_RESTART.
 689          *
 690          * We cannot use hrtimer_cancel() here as a running callback
 691          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 692          * would spin forever.
 693          */
 694         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 695                 return -1;
 696
 697         if (enabled) {
 698                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 699
 700                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 701         }
 702         return 0;
 703 }
 704
 705 /**
 706  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 707  * @rtc: the rtc device
 708  * @task: currently registered with rtc_irq_register()
 709  * @enabled: true to enable periodic IRQs
 710  * Context: any
 711  *
 712  * Note that rtc_irq_set_freq() should previously have been used to
 713  * specify the desired frequency of periodic IRQ task->func() callbacks.
 714  */
 715 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 716 {
 717         int err = 0;
 718         unsigned long flags;
 719
 720 retry:
 721         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 722         if (rtc->irq_task != NULL && task == NULL)
 723                 err = -EBUSY;
 724         else if (rtc->irq_task != task)
 725                 err = -EACCES;
 726         else {
 727                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 728                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 729                         cpu_relax();
 730                         goto retry;
 731                 }
 732                 rtc->pie_enabled = enabled;
 733         }
 734         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 735         return err;
 736 }
 737 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 738
 739 /**
 740  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 741  * @rtc: the rtc device
 742  * @task: currently registered with rtc_irq_register()
 743  * @freq: positive frequency with which task->func() will be called
 744  * Context: any
 745  *
 746  * Note that rtc_irq_set_state() is used to enable or disable the
 747  * periodic IRQs.
 748  */
 749 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 750 {
 751         int err = 0;
 752         unsigned long flags;
 753
 754         if (freq <= 0 || freq > RTC_MAX_FREQ)
 755                 return -EINVAL;
 756 retry:
 757         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 758         if (rtc->irq_task != NULL && task == NULL)
 759                 err = -EBUSY;
 760         else if (rtc->irq_task != task)
 761                 err = -EACCES;
 762         else {
 763                 rtc->irq_freq = freq;
 764                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 765                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 766                         cpu_relax();
 767                         goto retry;
 768                 }
 769         }
 770         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 771         return err;
 772 }
 773 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 774
 775 /**
 776  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 777  * @rtc rtc device
 778  * @timer timer being added.
 779  *
 780  * Enqueues a timer onto the rtc devices timerqueue and sets
 781  * the next alarm event appropriately.
 782  *
 783  * Sets the enabled bit on the added timer.
 784  *
 785  * Must hold ops_lock for proper serialization of timerqueue
 786  */
 787 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 788 {
 789         timer->enabled = 1;
 790         timerqueue_add(&rtc->timerqueue, &timer->node);
 791         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 792                 struct rtc_wkalrm alarm;
 793                 int err;
 794                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 795                 alarm.enabled = 1;
 796                 err = __rtc_set_alarm(rtc, &alarm);
 797                 if (err == -ETIME) {
 798                         pm_stay_awake(rtc->dev.parent);
 799                         schedule_work(&rtc->irqwork);
 800                 } else if (err) {
 801                         timerqueue_del(&rtc->timerqueue, &timer->node);
 802                         timer->enabled = 0;
 803                         return err;
 804                 }
 805         }
 806         return 0;
 807 }
 808
 809 static void rtc_alarm_disable(struct rtc_device *rtc)
 810 {
 811         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 812                 return;
 813
 814         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 815 }
 816
 817 /**
 818  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 819  * @rtc rtc device
 820  * @timer timer being removed.
 821  *
 822  * Removes a timer onto the rtc devices timerqueue and sets
 823  * the next alarm event appropriately.
 824  *
 825  * Clears the enabled bit on the removed timer.
 826  *
 827  * Must hold ops_lock for proper serialization of timerqueue
 828  */
 829 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 830 {
 831         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 832         timerqueue_del(&rtc->timerqueue, &timer->node);
 833         timer->enabled = 0;
 834         if (next == &timer->node) {
 835                 struct rtc_wkalrm alarm;
 836                 int err;
 837                 next = timerqueue_getnext(&rtc->timerqueue);
 838                 if (!next) {
 839                         rtc_alarm_disable(rtc);
 840                         return;
 841                 }
 842                 alarm.time = rtc_ktime_to_tm(next->expires);
 843                 alarm.enabled = 1;
 844                 err = __rtc_set_alarm(rtc, &alarm);
 845                 if (err == -ETIME) {
 846                         pm_stay_awake(rtc->dev.parent);
 847                         schedule_work(&rtc->irqwork);
 848                 }
 849         }
 850 }
 851
 852 /**
 853  * rtc_timer_do_work - Expires rtc timers
 854  * @rtc rtc device
 855  * @timer timer being removed.
 856  *
 857  * Expires rtc timers. Reprograms next alarm event if needed.
 858  * Called via worktask.
 859  *
 860  * Serializes access to timerqueue via ops_lock mutex
 861  */
 862 void rtc_timer_do_work(struct work_struct *work)
 863 {
 864         struct rtc_timer *timer;
 865         struct timerqueue_node *next;
 866         ktime_t now;
 867         struct rtc_time tm;
 868
 869         struct rtc_device *rtc =
 870                 container_of(work, struct rtc_device, irqwork);
 871
 872         mutex_lock(&rtc->ops_lock);
 873 again:
 874         __rtc_read_time(rtc, &tm);
 875         now = rtc_tm_to_ktime(tm);
 876         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 877                 if (next->expires.tv64 > now.tv64)
 878                         break;
 879
 880                 /* expire timer */
 881                 timer = container_of(next, struct rtc_timer, node);
 882                 timerqueue_del(&rtc->timerqueue, &timer->node);
 883                 timer->enabled = 0;
 884                 if (timer->task.func)
 885                         timer->task.func(timer->task.private_data);
 886
 887                 /* Re-add/fwd periodic timers */
 888                 if (ktime_to_ns(timer->period)) {
 889                         timer->node.expires = ktime_add(timer->node.expires,
 890                                                         timer->period);
 891                         timer->enabled = 1;
 892                         timerqueue_add(&rtc->timerqueue, &timer->node);
 893                 }
 894         }
 895
 896         /* Set next alarm */
 897         if (next) {
 898                 struct rtc_wkalrm alarm;
 899                 int err;
 900                 int retry = 3;
 901
 902                 alarm.time = rtc_ktime_to_tm(next->expires);
 903                 alarm.enabled = 1;
 904 reprogram:
 905                 err = __rtc_set_alarm(rtc, &alarm);
 906                 if (err == -ETIME)
 907                         goto again;
 908                 else if (err) {
 909                         if (retry-- > 0)
 910                                 goto reprogram;
 911
 912                         timer = container_of(next, struct rtc_timer, node);
 913                         timerqueue_del(&rtc->timerqueue, &timer->node);
 914                         timer->enabled = 0;
 915                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 916                         goto again;
 917                 }
 918         } else
 919                 rtc_alarm_disable(rtc);
 920
 921         pm_relax(rtc->dev.parent);
 922         mutex_unlock(&rtc->ops_lock);
 923 }
 924
 925
 926 /* rtc_timer_init - Initializes an rtc_timer
 927  * @timer: timer to be intiialized
 928  * @f: function pointer to be called when timer fires
 929  * @data: private data passed to function pointer
 930  *
 931  * Kernel interface to initializing an rtc_timer.
 932  */
 933 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 934 {
 935         timerqueue_init(&timer->node);
 936         timer->enabled = 0;
 937         timer->task.func = f;
 938         timer->task.private_data = data;
 939 }
 940
 941 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 942  * @ rtc: rtc device to be used
 943  * @ timer: timer being set
 944  * @ expires: time at which to expire the timer
 945  * @ period: period that the timer will recur
 946  *
 947  * Kernel interface to set an rtc_timer
 948  */
 949 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 950                         ktime_t expires, ktime_t period)
 951 {
 952         int ret = 0;
 953         mutex_lock(&rtc->ops_lock);
 954         if (timer->enabled)
 955                 rtc_timer_remove(rtc, timer);
 956
 957         timer->node.expires = expires;
 958         timer->period = period;
 959
 960         ret = rtc_timer_enqueue(rtc, timer);
 961
 962         mutex_unlock(&rtc->ops_lock);
 963         return ret;
 964 }
 965
 966 /* rtc_timer_cancel - Stops an rtc_timer
 967  * @ rtc: rtc device to be used
 968  * @ timer: timer being set
 969  *
 970  * Kernel interface to cancel an rtc_timer
 971  */
 972 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 973 {
 974         int ret = 0;
 975         mutex_lock(&rtc->ops_lock);
 976         if (timer->enabled)
 977                 rtc_timer_remove(rtc, timer);
 978         mutex_unlock(&rtc->ops_lock);
 979         return ret;
 980 }
 981
 982