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_dbg(&rtc->dev, "read_time: fail to read: %d\n",
  35                                 err);
  36                         return err;
  37                 }
  38
  39                 err = rtc_valid_tm(tm);
  40                 if (err < 0)
  41                         dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
  42         }
  43         return err;
  44 }
  45
  46 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
  47 {
  48         int err;
  49
  50         err = mutex_lock_interruptible(&rtc->ops_lock);
  51         if (err)
  52                 return err;
  53
  54         err = __rtc_read_time(rtc, tm);
  55         mutex_unlock(&rtc->ops_lock);
  56         return err;
  57 }
  58 EXPORT_SYMBOL_GPL(rtc_read_time);
  59
  60 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
  61 {
  62         int err;
  63
  64         err = rtc_valid_tm(tm);
  65         if (err != 0)
  66                 return err;
  67
  68         err = mutex_lock_interruptible(&rtc->ops_lock);
  69         if (err)
  70                 return err;
  71
  72         if (!rtc->ops)
  73                 err = -ENODEV;
  74         else if (rtc->ops->set_time)
  75                 err = rtc->ops->set_time(rtc->dev.parent, tm);
  76         else if (rtc->ops->set_mmss64) {
  77                 time64_t secs64 = rtc_tm_to_time64(tm);
  78
  79                 err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
  80         } else if (rtc->ops->set_mmss) {
  81                 time64_t secs64 = rtc_tm_to_time64(tm);
  82                 err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
  83         } else
  84                 err = -EINVAL;
  85
  86         pm_stay_awake(rtc->dev.parent);
  87         mutex_unlock(&rtc->ops_lock);
  88         /* A timer might have just expired */
  89         schedule_work(&rtc->irqwork);
  90         return err;
  91 }
  92 EXPORT_SYMBOL_GPL(rtc_set_time);
  93
  94 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  95 {
  96         int err;
  97
  98         err = mutex_lock_interruptible(&rtc->ops_lock);
  99         if (err)
 100                 return err;
 101
 102         if (!rtc->ops)
 103                 err = -ENODEV;
 104         else if (rtc->ops->set_mmss64)
 105                 err = rtc->ops->set_mmss64(rtc->dev.parent, secs);
 106         else if (rtc->ops->set_mmss)
 107                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 108         else if (rtc->ops->read_time && rtc->ops->set_time) {
 109                 struct rtc_time new, old;
 110
 111                 err = rtc->ops->read_time(rtc->dev.parent, &old);
 112                 if (err == 0) {
 113                         rtc_time64_to_tm(secs, &new);
 114
 115                         /*
 116                          * avoid writing when we're going to change the day of
 117                          * the month. We will retry in the next minute. This
 118                          * basically means that if the RTC must not drift
 119                          * by more than 1 minute in 11 minutes.
 120                          */
 121                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 122                                 (new.tm_hour == 23 && new.tm_min == 59)))
 123                                 err = rtc->ops->set_time(rtc->dev.parent,
 124                                                 &new);
 125                 }
 126         } else {
 127                 err = -EINVAL;
 128         }
 129
 130         pm_stay_awake(rtc->dev.parent);
 131         mutex_unlock(&rtc->ops_lock);
 132         /* A timer might have just expired */
 133         schedule_work(&rtc->irqwork);
 134
 135         return err;
 136 }
 137 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 138
 139 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 140 {
 141         int err;
 142
 143         err = mutex_lock_interruptible(&rtc->ops_lock);
 144         if (err)
 145                 return err;
 146
 147         if (rtc->ops == NULL)
 148                 err = -ENODEV;
 149         else if (!rtc->ops->read_alarm)
 150                 err = -EINVAL;
 151         else {
 152                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 153                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 154         }
 155
 156         mutex_unlock(&rtc->ops_lock);
 157         return err;
 158 }
 159
 160 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 161 {
 162         int err;
 163         struct rtc_time before, now;
 164         int first_time = 1;
 165         time64_t t_now, t_alm;
 166         enum { none, day, month, year } missing = none;
 167         unsigned days;
 168
 169         /* The lower level RTC driver may return -1 in some fields,
 170          * creating invalid alarm->time values, for reasons like:
 171          *
 172          *   - The hardware may not be capable of filling them in;
 173          *     many alarms match only on time-of-day fields, not
 174          *     day/month/year calendar data.
 175          *
 176          *   - Some hardware uses illegal values as "wildcard" match
 177          *     values, which non-Linux firmware (like a BIOS) may try
 178          *     to set up as e.g. "alarm 15 minutes after each hour".
 179          *     Linux uses only oneshot alarms.
 180          *
 181          * When we see that here, we deal with it by using values from
 182          * a current RTC timestamp for any missing (-1) values.  The
 183          * RTC driver prevents "periodic alarm" modes.
 184          *
 185          * But this can be racey, because some fields of the RTC timestamp
 186          * may have wrapped in the interval since we read the RTC alarm,
 187          * which would lead to us inserting inconsistent values in place
 188          * of the -1 fields.
 189          *
 190          * Reading the alarm and timestamp in the reverse sequence
 191          * would have the same race condition, and not solve the issue.
 192          *
 193          * So, we must first read the RTC timestamp,
 194          * then read the RTC alarm value,
 195          * and then read a second RTC timestamp.
 196          *
 197          * If any fields of the second timestamp have changed
 198          * when compared with the first timestamp, then we know
 199          * our timestamp may be inconsistent with that used by
 200          * the low-level rtc_read_alarm_internal() function.
 201          *
 202          * So, when the two timestamps disagree, we just loop and do
 203          * the process again to get a fully consistent set of values.
 204          *
 205          * This could all instead be done in the lower level driver,
 206          * but since more than one lower level RTC implementation needs it,
 207          * then it's probably best best to do it here instead of there..
 208          */
 209
 210         /* Get the "before" timestamp */
 211         err = rtc_read_time(rtc, &before);
 212         if (err < 0)
 213                 return err;
 214         do {
 215                 if (!first_time)
 216                         memcpy(&before, &now, sizeof(struct rtc_time));
 217                 first_time = 0;
 218
 219                 /* get the RTC alarm values, which may be incomplete */
 220                 err = rtc_read_alarm_internal(rtc, alarm);
 221                 if (err)
 222                         return err;
 223
 224                 /* full-function RTCs won't have such missing fields */
 225                 if (rtc_valid_tm(&alarm->time) == 0)
 226                         return 0;
 227
 228                 /* get the "after" timestamp, to detect wrapped fields */
 229                 err = rtc_read_time(rtc, &now);
 230                 if (err < 0)
 231                         return err;
 232
 233                 /* note that tm_sec is a "don't care" value here: */
 234         } while (   before.tm_min   != now.tm_min
 235                  || before.tm_hour  != now.tm_hour
 236                  || before.tm_mon   != now.tm_mon
 237                  || before.tm_year  != now.tm_year);
 238
 239         /* Fill in the missing alarm fields using the timestamp; we
 240          * know there's at least one since alarm->time is invalid.
 241          */
 242         if (alarm->time.tm_sec == -1)
 243                 alarm->time.tm_sec = now.tm_sec;
 244         if (alarm->time.tm_min == -1)
 245                 alarm->time.tm_min = now.tm_min;
 246         if (alarm->time.tm_hour == -1)
 247                 alarm->time.tm_hour = now.tm_hour;
 248
 249         /* For simplicity, only support date rollover for now */
 250         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 251                 alarm->time.tm_mday = now.tm_mday;
 252                 missing = day;
 253         }
 254         if ((unsigned)alarm->time.tm_mon >= 12) {
 255                 alarm->time.tm_mon = now.tm_mon;
 256                 if (missing == none)
 257                         missing = month;
 258         }
 259         if (alarm->time.tm_year == -1) {
 260                 alarm->time.tm_year = now.tm_year;
 261                 if (missing == none)
 262                         missing = year;
 263         }
 264
 265         /* with luck, no rollover is needed */
 266         t_now = rtc_tm_to_time64(&now);
 267         t_alm = rtc_tm_to_time64(&alarm->time);
 268         if (t_now < t_alm)
 269                 goto done;
 270
 271         switch (missing) {
 272
 273         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 274          * that will trigger at 5am will do so at 5am Tuesday, which
 275          * could also be in the next month or year.  This is a common
 276          * case, especially for PCs.
 277          */
 278         case day:
 279                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 280                 t_alm += 24 * 60 * 60;
 281                 rtc_time64_to_tm(t_alm, &alarm->time);
 282                 break;
 283
 284         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 285          * be next month.  An alarm matching on the 30th, 29th, or 28th
 286          * may end up in the month after that!  Many newer PCs support
 287          * this type of alarm.
 288          */
 289         case month:
 290                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 291                 do {
 292                         if (alarm->time.tm_mon < 11)
 293                                 alarm->time.tm_mon++;
 294                         else {
 295                                 alarm->time.tm_mon = 0;
 296                                 alarm->time.tm_year++;
 297                         }
 298                         days = rtc_month_days(alarm->time.tm_mon,
 299                                         alarm->time.tm_year);
 300                 } while (days < alarm->time.tm_mday);
 301                 break;
 302
 303         /* Year rollover ... easy except for leap years! */
 304         case year:
 305                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 306                 do {
 307                         alarm->time.tm_year++;
 308                 } while (!is_leap_year(alarm->time.tm_year + 1900)
 309                         && rtc_valid_tm(&alarm->time) != 0);
 310                 break;
 311
 312         default:
 313                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 314         }
 315
 316 done:
 317         err = rtc_valid_tm(&alarm->time);
 318
 319         if (err) {
 320                 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
 321                         alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
 322                         alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
 323                         alarm->time.tm_sec);
 324         }
 325
 326         return err;
 327 }
 328
 329 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 330 {
 331         int err;
 332
 333         err = mutex_lock_interruptible(&rtc->ops_lock);
 334         if (err)
 335                 return err;
 336         if (rtc->ops == NULL)
 337                 err = -ENODEV;
 338         else if (!rtc->ops->read_alarm)
 339                 err = -EINVAL;
 340         else {
 341                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 342                 alarm->enabled = rtc->aie_timer.enabled;
 343                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 344         }
 345         mutex_unlock(&rtc->ops_lock);
 346
 347         return err;
 348 }
 349 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 350
 351 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 352 {
 353         struct rtc_time tm;
 354         time64_t now, scheduled;
 355         int err;
 356
 357         err = rtc_valid_tm(&alarm->time);
 358         if (err)
 359                 return err;
 360         scheduled = rtc_tm_to_time64(&alarm->time);
 361
 362         /* Make sure we're not setting alarms in the past */
 363         err = __rtc_read_time(rtc, &tm);
 364         if (err)
 365                 return err;
 366         now = rtc_tm_to_time64(&tm);
 367         if (scheduled <= now)
 368                 return -ETIME;
 369         /*
 370          * XXX - We just checked to make sure the alarm time is not
 371          * in the past, but there is still a race window where if
 372          * the is alarm set for the next second and the second ticks
 373          * over right here, before we set the alarm.
 374          */
 375
 376         if (!rtc->ops)
 377                 err = -ENODEV;
 378         else if (!rtc->ops->set_alarm)
 379                 err = -EINVAL;
 380         else
 381                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 382
 383         return err;
 384 }
 385
 386 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 387 {
 388         int err;
 389
 390         err = rtc_valid_tm(&alarm->time);
 391         if (err != 0)
 392                 return err;
 393
 394         err = mutex_lock_interruptible(&rtc->ops_lock);
 395         if (err)
 396                 return err;
 397         if (rtc->aie_timer.enabled)
 398                 rtc_timer_remove(rtc, &rtc->aie_timer);
 399
 400         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 401         rtc->aie_timer.period = ktime_set(0, 0);
 402         if (alarm->enabled)
 403                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 404
 405         mutex_unlock(&rtc->ops_lock);
 406         return err;
 407 }
 408 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 409
 410 /* Called once per device from rtc_device_register */
 411 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 412 {
 413         int err;
 414         struct rtc_time now;
 415
 416         err = rtc_valid_tm(&alarm->time);
 417         if (err != 0)
 418                 return err;
 419
 420         err = rtc_read_time(rtc, &now);
 421         if (err)
 422                 return err;
 423
 424         err = mutex_lock_interruptible(&rtc->ops_lock);
 425         if (err)
 426                 return err;
 427
 428         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 429         rtc->aie_timer.period = ktime_set(0, 0);
 430
 431         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 432         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 433                          rtc->aie_timer.node.expires.tv64)) {
 434
 435                 rtc->aie_timer.enabled = 1;
 436                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 437         }
 438         mutex_unlock(&rtc->ops_lock);
 439         return err;
 440 }
 441 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 442
 443
 444
 445 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 446 {
 447         int err = mutex_lock_interruptible(&rtc->ops_lock);
 448         if (err)
 449                 return err;
 450
 451         if (rtc->aie_timer.enabled != enabled) {
 452                 if (enabled)
 453                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 454                 else
 455                         rtc_timer_remove(rtc, &rtc->aie_timer);
 456         }
 457
 458         if (err)
 459                 /* nothing */;
 460         else if (!rtc->ops)
 461                 err = -ENODEV;
 462         else if (!rtc->ops->alarm_irq_enable)
 463                 err = -EINVAL;
 464         else
 465                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 466
 467         mutex_unlock(&rtc->ops_lock);
 468         return err;
 469 }
 470 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 471
 472 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 473 {
 474         int err = mutex_lock_interruptible(&rtc->ops_lock);
 475         if (err)
 476                 return err;
 477
 478 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 479         if (enabled == 0 && rtc->uie_irq_active) {
 480                 mutex_unlock(&rtc->ops_lock);
 481                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 482         }
 483 #endif
 484         /* make sure we're changing state */
 485         if (rtc->uie_rtctimer.enabled == enabled)
 486                 goto out;
 487
 488         if (rtc->uie_unsupported) {
 489                 err = -EINVAL;
 490                 goto out;
 491         }
 492
 493         if (enabled) {
 494                 struct rtc_time tm;
 495                 ktime_t now, onesec;
 496
 497                 __rtc_read_time(rtc, &tm);
 498                 onesec = ktime_set(1, 0);
 499                 now = rtc_tm_to_ktime(tm);
 500                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 501                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 502                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 503         } else
 504                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 505
 506 out:
 507         mutex_unlock(&rtc->ops_lock);
 508 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 509         /*
 510          * Enable emulation if the driver did not provide
 511          * the update_irq_enable function pointer or if returned
 512          * -EINVAL to signal that it has been configured without
 513          * interrupts or that are not available at the moment.
 514          */
 515         if (err == -EINVAL)
 516                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 517 #endif
 518         return err;
 519
 520 }
 521 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 522
 523
 524 /**
 525  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 526  * @rtc: pointer to the rtc device
 527  *
 528  * This function is called when an AIE, UIE or PIE mode interrupt
 529  * has occurred (or been emulated).
 530  *
 531  * Triggers the registered irq_task function callback.
 532  */
 533 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 534 {
 535         unsigned long flags;
 536
 537         /* mark one irq of the appropriate mode */
 538         spin_lock_irqsave(&rtc->irq_lock, flags);
 539         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 540         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 541
 542         /* call the task func */
 543         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 544         if (rtc->irq_task)
 545                 rtc->irq_task->func(rtc->irq_task->private_data);
 546         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 547
 548         wake_up_interruptible(&rtc->irq_queue);
 549         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 550 }
 551
 552
 553 /**
 554  * rtc_aie_update_irq - AIE mode rtctimer hook
 555  * @private: pointer to the rtc_device
 556  *
 557  * This functions is called when the aie_timer expires.
 558  */
 559 void rtc_aie_update_irq(void *private)
 560 {
 561         struct rtc_device *rtc = (struct rtc_device *)private;
 562         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 563 }
 564
 565
 566 /**
 567  * rtc_uie_update_irq - UIE mode rtctimer hook
 568  * @private: pointer to the rtc_device
 569  *
 570  * This functions is called when the uie_timer expires.
 571  */
 572 void rtc_uie_update_irq(void *private)
 573 {
 574         struct rtc_device *rtc = (struct rtc_device *)private;
 575         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 576 }
 577
 578
 579 /**
 580  * rtc_pie_update_irq - PIE mode hrtimer hook
 581  * @timer: pointer to the pie mode hrtimer
 582  *
 583  * This function is used to emulate PIE mode interrupts
 584  * using an hrtimer. This function is called when the periodic
 585  * hrtimer expires.
 586  */
 587 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 588 {
 589         struct rtc_device *rtc;
 590         ktime_t period;
 591         int count;
 592         rtc = container_of(timer, struct rtc_device, pie_timer);
 593
 594         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 595         count = hrtimer_forward_now(timer, period);
 596
 597         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 598
 599         return HRTIMER_RESTART;
 600 }
 601
 602 /**
 603  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 604  * @rtc: the rtc device
 605  * @num: how many irqs are being reported (usually one)
 606  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 607  * Context: any
 608  */
 609 void rtc_update_irq(struct rtc_device *rtc,
 610                 unsigned long num, unsigned long events)
 611 {
 612         if (unlikely(IS_ERR_OR_NULL(rtc)))
 613                 return;
 614
 615         pm_stay_awake(rtc->dev.parent);
 616         schedule_work(&rtc->irqwork);
 617 }
 618 EXPORT_SYMBOL_GPL(rtc_update_irq);
 619
 620 static int __rtc_match(struct device *dev, const void *data)
 621 {
 622         const char *name = data;
 623
 624         if (strcmp(dev_name(dev), name) == 0)
 625                 return 1;
 626         return 0;
 627 }
 628
 629 struct rtc_device *rtc_class_open(const char *name)
 630 {
 631         struct device *dev;
 632         struct rtc_device *rtc = NULL;
 633
 634         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 635         if (dev)
 636                 rtc = to_rtc_device(dev);
 637
 638         if (rtc) {
 639                 if (!try_module_get(rtc->owner)) {
 640                         put_device(dev);
 641                         rtc = NULL;
 642                 }
 643         }
 644
 645         return rtc;
 646 }
 647 EXPORT_SYMBOL_GPL(rtc_class_open);
 648
 649 void rtc_class_close(struct rtc_device *rtc)
 650 {
 651         module_put(rtc->owner);
 652         put_device(&rtc->dev);
 653 }
 654 EXPORT_SYMBOL_GPL(rtc_class_close);
 655
 656 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 657 {
 658         int retval = -EBUSY;
 659
 660         if (task == NULL || task->func == NULL)
 661                 return -EINVAL;
 662
 663         /* Cannot register while the char dev is in use */
 664         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 665                 return -EBUSY;
 666
 667         spin_lock_irq(&rtc->irq_task_lock);
 668         if (rtc->irq_task == NULL) {
 669                 rtc->irq_task = task;
 670                 retval = 0;
 671         }
 672         spin_unlock_irq(&rtc->irq_task_lock);
 673
 674         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 675
 676         return retval;
 677 }
 678 EXPORT_SYMBOL_GPL(rtc_irq_register);
 679
 680 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 681 {
 682         spin_lock_irq(&rtc->irq_task_lock);
 683         if (rtc->irq_task == task)
 684                 rtc->irq_task = NULL;
 685         spin_unlock_irq(&rtc->irq_task_lock);
 686 }
 687 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 688
 689 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 690 {
 691         /*
 692          * We always cancel the timer here first, because otherwise
 693          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 694          * when we manage to start the timer before the callback
 695          * returns HRTIMER_RESTART.
 696          *
 697          * We cannot use hrtimer_cancel() here as a running callback
 698          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 699          * would spin forever.
 700          */
 701         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 702                 return -1;
 703
 704         if (enabled) {
 705                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 706
 707                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 708         }
 709         return 0;
 710 }
 711
 712 /**
 713  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 714  * @rtc: the rtc device
 715  * @task: currently registered with rtc_irq_register()
 716  * @enabled: true to enable periodic IRQs
 717  * Context: any
 718  *
 719  * Note that rtc_irq_set_freq() should previously have been used to
 720  * specify the desired frequency of periodic IRQ task->func() callbacks.
 721  */
 722 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 723 {
 724         int err = 0;
 725         unsigned long flags;
 726
 727 retry:
 728         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 729         if (rtc->irq_task != NULL && task == NULL)
 730                 err = -EBUSY;
 731         else if (rtc->irq_task != task)
 732                 err = -EACCES;
 733         else {
 734                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 735                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 736                         cpu_relax();
 737                         goto retry;
 738                 }
 739                 rtc->pie_enabled = enabled;
 740         }
 741         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 742         return err;
 743 }
 744 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 745
 746 /**
 747  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 748  * @rtc: the rtc device
 749  * @task: currently registered with rtc_irq_register()
 750  * @freq: positive frequency with which task->func() will be called
 751  * Context: any
 752  *
 753  * Note that rtc_irq_set_state() is used to enable or disable the
 754  * periodic IRQs.
 755  */
 756 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 757 {
 758         int err = 0;
 759         unsigned long flags;
 760
 761         if (freq <= 0 || freq > RTC_MAX_FREQ)
 762                 return -EINVAL;
 763 retry:
 764         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 765         if (rtc->irq_task != NULL && task == NULL)
 766                 err = -EBUSY;
 767         else if (rtc->irq_task != task)
 768                 err = -EACCES;
 769         else {
 770                 rtc->irq_freq = freq;
 771                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 772                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 773                         cpu_relax();
 774                         goto retry;
 775                 }
 776         }
 777         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 778         return err;
 779 }
 780 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 781
 782 /**
 783  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 784  * @rtc rtc device
 785  * @timer timer being added.
 786  *
 787  * Enqueues a timer onto the rtc devices timerqueue and sets
 788  * the next alarm event appropriately.
 789  *
 790  * Sets the enabled bit on the added timer.
 791  *
 792  * Must hold ops_lock for proper serialization of timerqueue
 793  */
 794 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 795 {
 796         timer->enabled = 1;
 797         timerqueue_add(&rtc->timerqueue, &timer->node);
 798         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 799                 struct rtc_wkalrm alarm;
 800                 int err;
 801                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 802                 alarm.enabled = 1;
 803                 err = __rtc_set_alarm(rtc, &alarm);
 804                 if (err == -ETIME) {
 805                         pm_stay_awake(rtc->dev.parent);
 806                         schedule_work(&rtc->irqwork);
 807                 } else if (err) {
 808                         timerqueue_del(&rtc->timerqueue, &timer->node);
 809                         timer->enabled = 0;
 810                         return err;
 811                 }
 812         }
 813         return 0;
 814 }
 815
 816 static void rtc_alarm_disable(struct rtc_device *rtc)
 817 {
 818         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 819                 return;
 820
 821         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 822 }
 823
 824 /**
 825  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 826  * @rtc rtc device
 827  * @timer timer being removed.
 828  *
 829  * Removes a timer onto the rtc devices timerqueue and sets
 830  * the next alarm event appropriately.
 831  *
 832  * Clears the enabled bit on the removed timer.
 833  *
 834  * Must hold ops_lock for proper serialization of timerqueue
 835  */
 836 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 837 {
 838         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 839         timerqueue_del(&rtc->timerqueue, &timer->node);
 840         timer->enabled = 0;
 841         if (next == &timer->node) {
 842                 struct rtc_wkalrm alarm;
 843                 int err;
 844                 next = timerqueue_getnext(&rtc->timerqueue);
 845                 if (!next) {
 846                         rtc_alarm_disable(rtc);
 847                         return;
 848                 }
 849                 alarm.time = rtc_ktime_to_tm(next->expires);
 850                 alarm.enabled = 1;
 851                 err = __rtc_set_alarm(rtc, &alarm);
 852                 if (err == -ETIME) {
 853                         pm_stay_awake(rtc->dev.parent);
 854                         schedule_work(&rtc->irqwork);
 855                 }
 856         }
 857 }
 858
 859 /**
 860  * rtc_timer_do_work - Expires rtc timers
 861  * @rtc rtc device
 862  * @timer timer being removed.
 863  *
 864  * Expires rtc timers. Reprograms next alarm event if needed.
 865  * Called via worktask.
 866  *
 867  * Serializes access to timerqueue via ops_lock mutex
 868  */
 869 void rtc_timer_do_work(struct work_struct *work)
 870 {
 871         struct rtc_timer *timer;
 872         struct timerqueue_node *next;
 873         ktime_t now;
 874         struct rtc_time tm;
 875
 876         struct rtc_device *rtc =
 877                 container_of(work, struct rtc_device, irqwork);
 878
 879         mutex_lock(&rtc->ops_lock);
 880 again:
 881         __rtc_read_time(rtc, &tm);
 882         now = rtc_tm_to_ktime(tm);
 883         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 884                 if (next->expires.tv64 > now.tv64)
 885                         break;
 886
 887                 /* expire timer */
 888                 timer = container_of(next, struct rtc_timer, node);
 889                 timerqueue_del(&rtc->timerqueue, &timer->node);
 890                 timer->enabled = 0;
 891                 if (timer->task.func)
 892                         timer->task.func(timer->task.private_data);
 893
 894                 /* Re-add/fwd periodic timers */
 895                 if (ktime_to_ns(timer->period)) {
 896                         timer->node.expires = ktime_add(timer->node.expires,
 897                                                         timer->period);
 898                         timer->enabled = 1;
 899                         timerqueue_add(&rtc->timerqueue, &timer->node);
 900                 }
 901         }
 902
 903         /* Set next alarm */
 904         if (next) {
 905                 struct rtc_wkalrm alarm;
 906                 int err;
 907                 int retry = 3;
 908
 909                 alarm.time = rtc_ktime_to_tm(next->expires);
 910                 alarm.enabled = 1;
 911 reprogram:
 912                 err = __rtc_set_alarm(rtc, &alarm);
 913                 if (err == -ETIME)
 914                         goto again;
 915                 else if (err) {
 916                         if (retry-- > 0)
 917                                 goto reprogram;
 918
 919                         timer = container_of(next, struct rtc_timer, node);
 920                         timerqueue_del(&rtc->timerqueue, &timer->node);
 921                         timer->enabled = 0;
 922                         dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
 923                         goto again;
 924                 }
 925         } else
 926                 rtc_alarm_disable(rtc);
 927
 928         pm_relax(rtc->dev.parent);
 929         mutex_unlock(&rtc->ops_lock);
 930 }
 931
 932
 933 /* rtc_timer_init - Initializes an rtc_timer
 934  * @timer: timer to be intiialized
 935  * @f: function pointer to be called when timer fires
 936  * @data: private data passed to function pointer
 937  *
 938  * Kernel interface to initializing an rtc_timer.
 939  */
 940 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
 941 {
 942         timerqueue_init(&timer->node);
 943         timer->enabled = 0;
 944         timer->task.func = f;
 945         timer->task.private_data = data;
 946 }
 947
 948 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 949  * @ rtc: rtc device to be used
 950  * @ timer: timer being set
 951  * @ expires: time at which to expire the timer
 952  * @ period: period that the timer will recur
 953  *
 954  * Kernel interface to set an rtc_timer
 955  */
 956 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
 957                         ktime_t expires, ktime_t period)
 958 {
 959         int ret = 0;
 960         mutex_lock(&rtc->ops_lock);
 961         if (timer->enabled)
 962                 rtc_timer_remove(rtc, timer);
 963
 964         timer->node.expires = expires;
 965         timer->period = period;
 966
 967         ret = rtc_timer_enqueue(rtc, timer);
 968
 969         mutex_unlock(&rtc->ops_lock);
 970         return ret;
 971 }
 972
 973 /* rtc_timer_cancel - Stops an rtc_timer
 974  * @ rtc: rtc device to be used
 975  * @ timer: timer being set
 976  *
 977  * Kernel interface to cancel an rtc_timer
 978  */
 979 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
 980 {
 981         int ret = 0;
 982         mutex_lock(&rtc->ops_lock);
 983         if (timer->enabled)
 984                 rtc_timer_remove(rtc, timer);
 985         mutex_unlock(&rtc->ops_lock);
 986         return ret;
 987 }
 988
 989