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         mutex_unlock(&rtc->ops_lock);
  76         /* A timer might have just expired */
  77         schedule_work(&rtc->irqwork);
  78         return err;
  79 }
  80 EXPORT_SYMBOL_GPL(rtc_set_time);
  81
  82 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  83 {
  84         int err;
  85
  86         err = mutex_lock_interruptible(&rtc->ops_lock);
  87         if (err)
  88                 return err;
  89
  90         if (!rtc->ops)
  91                 err = -ENODEV;
  92         else if (rtc->ops->set_mmss)
  93                 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  94         else if (rtc->ops->read_time && rtc->ops->set_time) {
  95                 struct rtc_time new, old;
  96
  97                 err = rtc->ops->read_time(rtc->dev.parent, &old);
  98                 if (err == 0) {
  99                         rtc_time_to_tm(secs, &new);
 100
 101                         /*
 102                          * avoid writing when we're going to change the day of
 103                          * the month. We will retry in the next minute. This
 104                          * basically means that if the RTC must not drift
 105                          * by more than 1 minute in 11 minutes.
 106                          */
 107                         if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 108                                 (new.tm_hour == 23 && new.tm_min == 59)))
 109                                 err = rtc->ops->set_time(rtc->dev.parent,
 110                                                 &new);
 111                 }
 112         }
 113         else
 114                 err = -EINVAL;
 115
 116         mutex_unlock(&rtc->ops_lock);
 117         /* A timer might have just expired */
 118         schedule_work(&rtc->irqwork);
 119
 120         return err;
 121 }
 122 EXPORT_SYMBOL_GPL(rtc_set_mmss);
 123
 124 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 125 {
 126         int err;
 127
 128         err = mutex_lock_interruptible(&rtc->ops_lock);
 129         if (err)
 130                 return err;
 131
 132         if (rtc->ops == NULL)
 133                 err = -ENODEV;
 134         else if (!rtc->ops->read_alarm)
 135                 err = -EINVAL;
 136         else {
 137                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 138                 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 139         }
 140
 141         mutex_unlock(&rtc->ops_lock);
 142         return err;
 143 }
 144
 145 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 146 {
 147         int err;
 148         struct rtc_time before, now;
 149         int first_time = 1;
 150         unsigned long t_now, t_alm;
 151         enum { none, day, month, year } missing = none;
 152         unsigned days;
 153
 154         /* The lower level RTC driver may return -1 in some fields,
 155          * creating invalid alarm->time values, for reasons like:
 156          *
 157          *   - The hardware may not be capable of filling them in;
 158          *     many alarms match only on time-of-day fields, not
 159          *     day/month/year calendar data.
 160          *
 161          *   - Some hardware uses illegal values as "wildcard" match
 162          *     values, which non-Linux firmware (like a BIOS) may try
 163          *     to set up as e.g. "alarm 15 minutes after each hour".
 164          *     Linux uses only oneshot alarms.
 165          *
 166          * When we see that here, we deal with it by using values from
 167          * a current RTC timestamp for any missing (-1) values.  The
 168          * RTC driver prevents "periodic alarm" modes.
 169          *
 170          * But this can be racey, because some fields of the RTC timestamp
 171          * may have wrapped in the interval since we read the RTC alarm,
 172          * which would lead to us inserting inconsistent values in place
 173          * of the -1 fields.
 174          *
 175          * Reading the alarm and timestamp in the reverse sequence
 176          * would have the same race condition, and not solve the issue.
 177          *
 178          * So, we must first read the RTC timestamp,
 179          * then read the RTC alarm value,
 180          * and then read a second RTC timestamp.
 181          *
 182          * If any fields of the second timestamp have changed
 183          * when compared with the first timestamp, then we know
 184          * our timestamp may be inconsistent with that used by
 185          * the low-level rtc_read_alarm_internal() function.
 186          *
 187          * So, when the two timestamps disagree, we just loop and do
 188          * the process again to get a fully consistent set of values.
 189          *
 190          * This could all instead be done in the lower level driver,
 191          * but since more than one lower level RTC implementation needs it,
 192          * then it's probably best best to do it here instead of there..
 193          */
 194
 195         /* Get the "before" timestamp */
 196         err = rtc_read_time(rtc, &before);
 197         if (err < 0)
 198                 return err;
 199         do {
 200                 if (!first_time)
 201                         memcpy(&before, &now, sizeof(struct rtc_time));
 202                 first_time = 0;
 203
 204                 /* get the RTC alarm values, which may be incomplete */
 205                 err = rtc_read_alarm_internal(rtc, alarm);
 206                 if (err)
 207                         return err;
 208
 209                 /* full-function RTCs won't have such missing fields */
 210                 if (rtc_valid_tm(&alarm->time) == 0)
 211                         return 0;
 212
 213                 /* get the "after" timestamp, to detect wrapped fields */
 214                 err = rtc_read_time(rtc, &now);
 215                 if (err < 0)
 216                         return err;
 217
 218                 /* note that tm_sec is a "don't care" value here: */
 219         } while (   before.tm_min   != now.tm_min
 220                  || before.tm_hour  != now.tm_hour
 221                  || before.tm_mon   != now.tm_mon
 222                  || before.tm_year  != now.tm_year);
 223
 224         /* Fill in the missing alarm fields using the timestamp; we
 225          * know there's at least one since alarm->time is invalid.
 226          */
 227         if (alarm->time.tm_sec == -1)
 228                 alarm->time.tm_sec = now.tm_sec;
 229         if (alarm->time.tm_min == -1)
 230                 alarm->time.tm_min = now.tm_min;
 231         if (alarm->time.tm_hour == -1)
 232                 alarm->time.tm_hour = now.tm_hour;
 233
 234         /* For simplicity, only support date rollover for now */
 235         if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 236                 alarm->time.tm_mday = now.tm_mday;
 237                 missing = day;
 238         }
 239         if ((unsigned)alarm->time.tm_mon >= 12) {
 240                 alarm->time.tm_mon = now.tm_mon;
 241                 if (missing == none)
 242                         missing = month;
 243         }
 244         if (alarm->time.tm_year == -1) {
 245                 alarm->time.tm_year = now.tm_year;
 246                 if (missing == none)
 247                         missing = year;
 248         }
 249
 250         /* with luck, no rollover is needed */
 251         rtc_tm_to_time(&now, &t_now);
 252         rtc_tm_to_time(&alarm->time, &t_alm);
 253         if (t_now < t_alm)
 254                 goto done;
 255
 256         switch (missing) {
 257
 258         /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 259          * that will trigger at 5am will do so at 5am Tuesday, which
 260          * could also be in the next month or year.  This is a common
 261          * case, especially for PCs.
 262          */
 263         case day:
 264                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 265                 t_alm += 24 * 60 * 60;
 266                 rtc_time_to_tm(t_alm, &alarm->time);
 267                 break;
 268
 269         /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 270          * be next month.  An alarm matching on the 30th, 29th, or 28th
 271          * may end up in the month after that!  Many newer PCs support
 272          * this type of alarm.
 273          */
 274         case month:
 275                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 276                 do {
 277                         if (alarm->time.tm_mon < 11)
 278                                 alarm->time.tm_mon++;
 279                         else {
 280                                 alarm->time.tm_mon = 0;
 281                                 alarm->time.tm_year++;
 282                         }
 283                         days = rtc_month_days(alarm->time.tm_mon,
 284                                         alarm->time.tm_year);
 285                 } while (days < alarm->time.tm_mday);
 286                 break;
 287
 288         /* Year rollover ... easy except for leap years! */
 289         case year:
 290                 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 291                 do {
 292                         alarm->time.tm_year++;
 293                 } while (rtc_valid_tm(&alarm->time) != 0);
 294                 break;
 295
 296         default:
 297                 dev_warn(&rtc->dev, "alarm rollover not handled\n");
 298         }
 299
 300 done:
 301         return 0;
 302 }
 303
 304 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 305 {
 306 #ifdef RTC_LEGACY_ALARM_IMPL
 307         return __rtc_read_alarm(rtc, alarm);
 308 #else
 309         int err;
 310
 311         err = mutex_lock_interruptible(&rtc->ops_lock);
 312         if (err)
 313                 return err;
 314         if (rtc->ops == NULL)
 315                 err = -ENODEV;
 316         else if (!rtc->ops->read_alarm)
 317                 err = -EINVAL;
 318         else {
 319                 memset(alarm, 0, sizeof(struct rtc_wkalrm));
 320                 alarm->enabled = rtc->aie_timer.enabled;
 321                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 322         }
 323         mutex_unlock(&rtc->ops_lock);
 324
 325         return err;
 326 #endif
 327 }
 328 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 329
 330 static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 331 {
 332 #ifdef RTC_LEGACY_ALARM_IMPL
 333         WARN(1, "__rtc_set_alarm() is not supported!!\n");
 334         return -EPERM;
 335 #else
 336         struct rtc_time tm;
 337         long now, scheduled;
 338         int err;
 339
 340         err = rtc_valid_tm(&alarm->time);
 341         if (err)
 342                 return err;
 343         rtc_tm_to_time(&alarm->time, &scheduled);
 344
 345         /* Make sure we're not setting alarms in the past */
 346         err = __rtc_read_time(rtc, &tm);
 347         rtc_tm_to_time(&tm, &now);
 348         if (scheduled <= now)
 349                 return -ETIME;
 350         /*
 351          * XXX - We just checked to make sure the alarm time is not
 352          * in the past, but there is still a race window where if
 353          * the is alarm set for the next second and the second ticks
 354          * over right here, before we set the alarm.
 355          */
 356
 357         if (!rtc->ops)
 358                 err = -ENODEV;
 359         else if (!rtc->ops->set_alarm)
 360                 err = -EINVAL;
 361         else
 362                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 363
 364         return err;
 365 #endif
 366 }
 367
 368 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 369 {
 370         int err;
 371
 372         err = rtc_valid_tm(&alarm->time);
 373         if (err != 0)
 374                 return err;
 375
 376         err = mutex_lock_interruptible(&rtc->ops_lock);
 377         if (err)
 378                 return err;
 379 #ifdef RTC_LEGACY_ALARM_IMPL
 380         if (!rtc->ops)
 381                 err = -ENODEV;
 382         else if (!rtc->ops->set_alarm)
 383                 err = -EINVAL;
 384         else
 385                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 386 #else
 387
 388         if (rtc->aie_timer.enabled) {
 389                 rtc_timer_remove(rtc, &rtc->aie_timer);
 390         }
 391         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 392         rtc->aie_timer.period = ktime_set(0, 0);
 393         if (alarm->enabled) {
 394                 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 395         }
 396 #endif
 397         mutex_unlock(&rtc->ops_lock);
 398         return err;
 399 }
 400 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 401
 402 int rtc_set_alarm_poweron(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 403 {
 404         int err;
 405
 406         err = rtc_valid_tm(&alarm->time);
 407         if (err != 0)
 408                 return err;
 409
 410         err = mutex_lock_interruptible(&rtc->ops_lock);
 411         if (err)
 412                 return err;
 413
 414         if (!rtc->ops)
 415                 err = -ENODEV;
 416         else if (!rtc->ops->set_alarm)
 417                 err = -EINVAL;
 418         else
 419                 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 420
 421         mutex_unlock(&rtc->ops_lock);
 422         return err;
 423 }
 424 EXPORT_SYMBOL_GPL(rtc_set_alarm_poweron);
 425
 426 /* Called once per device from rtc_device_register */
 427 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 428 {
 429 #ifdef RTC_LEGACY_ALARM_IMPL
 430                         return 0;
 431 #else
 432         int err;
 433         struct rtc_time now;
 434
 435         err = rtc_valid_tm(&alarm->time);
 436         if (err != 0)
 437                 return err;
 438
 439         err = rtc_read_time(rtc, &now);
 440         if (err)
 441                 return err;
 442
 443         err = mutex_lock_interruptible(&rtc->ops_lock);
 444         if (err)
 445                 return err;
 446
 447         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 448         rtc->aie_timer.period = ktime_set(0, 0);
 449
 450         /* Alarm has to be enabled & in the futrure for us to enqueue it */
 451         if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
 452                          rtc->aie_timer.node.expires.tv64)) {
 453
 454                 rtc->aie_timer.enabled = 1;
 455                 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 456         }
 457         mutex_unlock(&rtc->ops_lock);
 458         return err;
 459 #endif
 460 }
 461 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 462
 463
 464
 465 int rtc_alarm_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         if (rtc->aie_timer.enabled != enabled) {
 472                 if (enabled)
 473                         err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 474                 else
 475                         rtc_timer_remove(rtc, &rtc->aie_timer);
 476         }
 477
 478         if (err)
 479                 /* nothing */;
 480         else if (!rtc->ops)
 481                 err = -ENODEV;
 482         else if (!rtc->ops->alarm_irq_enable)
 483                 err = -EINVAL;
 484         else
 485                 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 486
 487         mutex_unlock(&rtc->ops_lock);
 488         return err;
 489 }
 490 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 491
 492 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 493 {
 494         int err = mutex_lock_interruptible(&rtc->ops_lock);
 495         if (err)
 496                 return err;
 497
 498 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 499         if (enabled == 0 && rtc->uie_irq_active) {
 500                 mutex_unlock(&rtc->ops_lock);
 501                 return rtc_dev_update_irq_enable_emul(rtc, 0);
 502         }
 503 #endif
 504         /* make sure we're changing state */
 505         if (rtc->uie_rtctimer.enabled == enabled)
 506                 goto out;
 507
 508         if (rtc->uie_unsupported) {
 509                 err = -EINVAL;
 510                 goto out;
 511         }
 512
 513         if (enabled) {
 514                 struct rtc_time tm;
 515                 ktime_t now, onesec;
 516
 517                 __rtc_read_time(rtc, &tm);
 518                 onesec = ktime_set(1, 0);
 519                 now = rtc_tm_to_ktime(tm);
 520                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 521                 rtc->uie_rtctimer.period = ktime_set(1, 0);
 522                 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 523         } else
 524                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 525
 526 out:
 527         mutex_unlock(&rtc->ops_lock);
 528 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 529         /*
 530          * Enable emulation if the driver did not provide
 531          * the update_irq_enable function pointer or if returned
 532          * -EINVAL to signal that it has been configured without
 533          * interrupts or that are not available at the moment.
 534          */
 535         if (err == -EINVAL)
 536                 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 537 #endif
 538         return err;
 539
 540 }
 541 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 542
 543
 544 /**
 545  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 546  * @rtc: pointer to the rtc device
 547  *
 548  * This function is called when an AIE, UIE or PIE mode interrupt
 549  * has occurred (or been emulated).
 550  *
 551  * Triggers the registered irq_task function callback.
 552  */
 553 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 554 {
 555         unsigned long flags;
 556
 557         /* mark one irq of the appropriate mode */
 558         spin_lock_irqsave(&rtc->irq_lock, flags);
 559         rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 560         spin_unlock_irqrestore(&rtc->irq_lock, flags);
 561
 562         /* call the task func */
 563         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 564         if (rtc->irq_task)
 565                 rtc->irq_task->func(rtc->irq_task->private_data);
 566         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 567
 568         wake_up_interruptible(&rtc->irq_queue);
 569         kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 570 }
 571
 572
 573 /**
 574  * rtc_aie_update_irq - AIE mode rtctimer hook
 575  * @private: pointer to the rtc_device
 576  *
 577  * This functions is called when the aie_timer expires.
 578  */
 579 void rtc_aie_update_irq(void *private)
 580 {
 581         struct rtc_device *rtc = (struct rtc_device *)private;
 582         rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 583 }
 584
 585
 586 /**
 587  * rtc_uie_update_irq - UIE mode rtctimer hook
 588  * @private: pointer to the rtc_device
 589  *
 590  * This functions is called when the uie_timer expires.
 591  */
 592 void rtc_uie_update_irq(void *private)
 593 {
 594         struct rtc_device *rtc = (struct rtc_device *)private;
 595         rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 596 }
 597
 598
 599 /**
 600  * rtc_pie_update_irq - PIE mode hrtimer hook
 601  * @timer: pointer to the pie mode hrtimer
 602  *
 603  * This function is used to emulate PIE mode interrupts
 604  * using an hrtimer. This function is called when the periodic
 605  * hrtimer expires.
 606  */
 607 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 608 {
 609         struct rtc_device *rtc;
 610         ktime_t period;
 611         int count;
 612         rtc = container_of(timer, struct rtc_device, pie_timer);
 613
 614         period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 615         count = hrtimer_forward_now(timer, period);
 616
 617         rtc_handle_legacy_irq(rtc, count, RTC_PF);
 618
 619         return HRTIMER_RESTART;
 620 }
 621
 622 /**
 623  * rtc_update_irq - Triggered when a RTC interrupt occurs.
 624  * @rtc: the rtc device
 625  * @num: how many irqs are being reported (usually one)
 626  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 627  * Context: any
 628  */
 629 void rtc_update_irq(struct rtc_device *rtc,
 630                 unsigned long num, unsigned long events)
 631 {
 632         pm_stay_awake(rtc->dev.parent);
 633         schedule_work(&rtc->irqwork);
 634 }
 635 EXPORT_SYMBOL_GPL(rtc_update_irq);
 636
 637 static int __rtc_match(struct device *dev, const void *data)
 638 {
 639         const char *name = data;
 640
 641         if (strcmp(dev_name(dev), name) == 0)
 642                 return 1;
 643         return 0;
 644 }
 645
 646 struct rtc_device *rtc_class_open(const char *name)
 647 {
 648         struct device *dev;
 649         struct rtc_device *rtc = NULL;
 650
 651         dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 652         if (dev)
 653                 rtc = to_rtc_device(dev);
 654
 655         if (rtc) {
 656                 if (!try_module_get(rtc->owner)) {
 657                         put_device(dev);
 658                         rtc = NULL;
 659                 }
 660         }
 661
 662         return rtc;
 663 }
 664 EXPORT_SYMBOL_GPL(rtc_class_open);
 665
 666 void rtc_class_close(struct rtc_device *rtc)
 667 {
 668         module_put(rtc->owner);
 669         put_device(&rtc->dev);
 670 }
 671 EXPORT_SYMBOL_GPL(rtc_class_close);
 672
 673 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 674 {
 675         int retval = -EBUSY;
 676
 677         if (task == NULL || task->func == NULL)
 678                 return -EINVAL;
 679
 680         /* Cannot register while the char dev is in use */
 681         if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 682                 return -EBUSY;
 683
 684         spin_lock_irq(&rtc->irq_task_lock);
 685         if (rtc->irq_task == NULL) {
 686                 rtc->irq_task = task;
 687                 retval = 0;
 688         }
 689         spin_unlock_irq(&rtc->irq_task_lock);
 690
 691         clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 692
 693         return retval;
 694 }
 695 EXPORT_SYMBOL_GPL(rtc_irq_register);
 696
 697 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 698 {
 699         spin_lock_irq(&rtc->irq_task_lock);
 700         if (rtc->irq_task == task)
 701                 rtc->irq_task = NULL;
 702         spin_unlock_irq(&rtc->irq_task_lock);
 703 }
 704 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 705
 706 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 707 {
 708         /*
 709          * We always cancel the timer here first, because otherwise
 710          * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 711          * when we manage to start the timer before the callback
 712          * returns HRTIMER_RESTART.
 713          *
 714          * We cannot use hrtimer_cancel() here as a running callback
 715          * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 716          * would spin forever.
 717          */
 718         if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 719                 return -1;
 720
 721         if (enabled) {
 722                 ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 723
 724                 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 725         }
 726         return 0;
 727 }
 728
 729 /**
 730  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 731  * @rtc: the rtc device
 732  * @task: currently registered with rtc_irq_register()
 733  * @enabled: true to enable periodic IRQs
 734  * Context: any
 735  *
 736  * Note that rtc_irq_set_freq() should previously have been used to
 737  * specify the desired frequency of periodic IRQ task->func() callbacks.
 738  */
 739 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 740 {
 741         int err = 0;
 742         unsigned long flags;
 743
 744 retry:
 745         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 746         if (rtc->irq_task != NULL && task == NULL)
 747                 err = -EBUSY;
 748         if (rtc->irq_task != task)
 749                 err = -EACCES;
 750         if (!err) {
 751                 if (rtc_update_hrtimer(rtc, enabled) < 0) {
 752                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 753                         cpu_relax();
 754                         goto retry;
 755                 }
 756                 rtc->pie_enabled = enabled;
 757         }
 758         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 759         return err;
 760 }
 761 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 762
 763 /**
 764  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 765  * @rtc: the rtc device
 766  * @task: currently registered with rtc_irq_register()
 767  * @freq: positive frequency with which task->func() will be called
 768  * Context: any
 769  *
 770  * Note that rtc_irq_set_state() is used to enable or disable the
 771  * periodic IRQs.
 772  */
 773 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 774 {
 775         int err = 0;
 776         unsigned long flags;
 777
 778         if (freq <= 0 || freq > RTC_MAX_FREQ)
 779                 return -EINVAL;
 780 retry:
 781         spin_lock_irqsave(&rtc->irq_task_lock, flags);
 782         if (rtc->irq_task != NULL && task == NULL)
 783                 err = -EBUSY;
 784         if (rtc->irq_task != task)
 785                 err = -EACCES;
 786         if (!err) {
 787                 rtc->irq_freq = freq;
 788                 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 789                         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 790                         cpu_relax();
 791                         goto retry;
 792                 }
 793         }
 794         spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 795         return err;
 796 }
 797 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 798
 799 /**
 800  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 801  * @rtc rtc device
 802  * @timer timer being added.
 803  *
 804  * Enqueues a timer onto the rtc devices timerqueue and sets
 805  * the next alarm event appropriately.
 806  *
 807  * Sets the enabled bit on the added timer.
 808  *
 809  * Must hold ops_lock for proper serialization of timerqueue
 810  */
 811 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 812 {
 813         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 814         struct rtc_time tm;
 815         ktime_t now;
 816
 817         timer->enabled = 1;
 818         __rtc_read_time(rtc, &tm);
 819         now = rtc_tm_to_ktime(tm);
 820
 821         /* Skip over expired timers */
 822         while (next) {
 823                 if (next->expires.tv64 >= now.tv64)
 824                         break;
 825                 next = timerqueue_iterate_next(next);
 826         }
 827
 828         timerqueue_add(&rtc->timerqueue, &timer->node);
 829         if (!next) {
 830                 struct rtc_wkalrm alarm;
 831                 int err;
 832                 alarm.time = rtc_ktime_to_tm(timer->node.expires);
 833                 alarm.enabled = 1;
 834                 err = __rtc_set_alarm(rtc, &alarm);
 835                 if (err == -ETIME)
 836                         schedule_work(&rtc->irqwork);
 837                 else if (err) {
 838                         timerqueue_del(&rtc->timerqueue, &timer->node);
 839                         timer->enabled = 0;
 840                         return err;
 841                 }
 842         }
 843         return 0;
 844 }
 845
 846 static void rtc_alarm_disable(struct rtc_device *rtc)
 847 {
 848         if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 849                 return;
 850
 851         rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 852 }
 853
 854 /**
 855  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 856  * @rtc rtc device
 857  * @timer timer being removed.
 858  *
 859  * Removes a timer onto the rtc devices timerqueue and sets
 860  * the next alarm event appropriately.
 861  *
 862  * Clears the enabled bit on the removed timer.
 863  *
 864  * Must hold ops_lock for proper serialization of timerqueue
 865  */
 866 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 867 {
 868         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 869         timerqueue_del(&rtc->timerqueue, &timer->node);
 870         timer->enabled = 0;
 871         if (next == &timer->node) {
 872                 struct rtc_wkalrm alarm;
 873                 int err;
 874                 next = timerqueue_getnext(&rtc->timerqueue);
 875                 if (!next) {
 876                         rtc_alarm_disable(rtc);
 877                         return;
 878                 }
 879                 alarm.time = rtc_ktime_to_tm(next->expires);
 880                 alarm.enabled = 1;
 881                 err = __rtc_set_alarm(rtc, &alarm);
 882                 if (err == -ETIME)
 883                         schedule_work(&rtc->irqwork);
 884         }
 885 }
 886
 887 /**
 888  * rtc_timer_do_work - Expires rtc timers
 889  * @rtc rtc device
 890  * @timer timer being removed.
 891  *
 892  * Expires rtc timers. Reprograms next alarm event if needed.
 893  * Called via worktask.
 894  *
 895  * Serializes access to timerqueue via ops_lock mutex
 896  */
 897 void rtc_timer_do_work(struct work_struct *work)
 898 {
 899         struct rtc_timer *timer;
 900         struct timerqueue_node *next;
 901         ktime_t now;
 902         struct rtc_time tm;
 903
 904         struct rtc_device *rtc =
 905                 container_of(work, struct rtc_device, irqwork);
 906
 907         mutex_lock(&rtc->ops_lock);
 908 again:
 909         pm_relax(rtc->dev.parent);
 910         __rtc_read_time(rtc, &tm);
 911         now = rtc_tm_to_ktime(tm);
 912         while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 913                 if (next->expires.tv64 > now.tv64)
 914                         break;
 915
 916                 /* expire timer */
 917                 timer = container_of(next, struct rtc_timer, node);
 918                 timerqueue_del(&rtc->timerqueue, &timer->node);
 919                 timer->enabled = 0;
 920                 if (timer->task.func)
 921                         timer->task.func(timer->task.private_data);
 922
 923                 /* Re-add/fwd periodic timers */
 924                 if (ktime_to_ns(timer->period)) {
 925                         timer->node.expires = ktime_add(timer->node.expires,
 926                                                         timer->period);
 927                         timer->enabled = 1;
 928                         timerqueue_add(&rtc->timerqueue, &timer->node);
 929                 }
 930         }
 931
 932         /* Set next alarm */
 933         if (next) {
 934                 struct rtc_wkalrm alarm;
 935                 int err;
 936                 alarm.time = rtc_ktime_to_tm(next->expires);
 937                 alarm.enabled = 1;
 938                 err = __rtc_set_alarm(rtc, &alarm);
 939                 if (err == -ETIME)
 940                         goto again;
 941         } else
 942                 rtc_alarm_disable(rtc);
 943
 944         mutex_unlock(&rtc->ops_lock);
 945 }
 946
 947
 948 /* rtc_timer_init - Initializes an rtc_timer
 949  * @timer: timer to be intiialized
 950  * @f: function pointer to be called when timer fires
 951  * @data: private data passed to function pointer
 952  *
 953  * Kernel interface to initializing an rtc_timer.
 954  */
 955 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data)
 956 {
 957         timerqueue_init(&timer->node);
 958         timer->enabled = 0;
 959         timer->task.func = f;
 960         timer->task.private_data = data;
 961 }
 962
 963 /* rtc_timer_start - Sets an rtc_timer to fire in the future
 964  * @ rtc: rtc device to be used
 965  * @ timer: timer being set
 966  * @ expires: time at which to expire the timer
 967  * @ period: period that the timer will recur
 968  *
 969  * Kernel interface to set an rtc_timer
 970  */
 971 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
 972                         ktime_t expires, ktime_t period)
 973 {
 974         int ret = 0;
 975         mutex_lock(&rtc->ops_lock);
 976         if (timer->enabled)
 977                 rtc_timer_remove(rtc, timer);
 978
 979         timer->node.expires = expires;
 980         timer->period = period;
 981
 982         ret = rtc_timer_enqueue(rtc, timer);
 983
 984         mutex_unlock(&rtc->ops_lock);
 985         return ret;
 986 }
 987
 988 /* rtc_timer_cancel - Stops an rtc_timer
 989  * @ rtc: rtc device to be used
 990  * @ timer: timer being set
 991  *
 992  * Kernel interface to cancel an rtc_timer
 993  */
 994 int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
 995 {
 996         int ret = 0;
 997         mutex_lock(&rtc->ops_lock);
 998         if (timer->enabled)
 999                 rtc_timer_remove(rtc, timer);
1000         mutex_unlock(&rtc->ops_lock);
1001         return ret;
1002 }
1003
1004