linux/drivers/rtc/interface.c
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   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
  20static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
  21static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
  22
  23static 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
  37int 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}
  49EXPORT_SYMBOL_GPL(rtc_read_time);
  50
  51int 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        return err;
  77}
  78EXPORT_SYMBOL_GPL(rtc_set_time);
  79
  80int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
  81{
  82        int err;
  83
  84        err = mutex_lock_interruptible(&rtc->ops_lock);
  85        if (err)
  86                return err;
  87
  88        if (!rtc->ops)
  89                err = -ENODEV;
  90        else if (rtc->ops->set_mmss)
  91                err = rtc->ops->set_mmss(rtc->dev.parent, secs);
  92        else if (rtc->ops->read_time && rtc->ops->set_time) {
  93                struct rtc_time new, old;
  94
  95                err = rtc->ops->read_time(rtc->dev.parent, &old);
  96                if (err == 0) {
  97                        rtc_time_to_tm(secs, &new);
  98
  99                        /*
 100                         * avoid writing when we're going to change the day of
 101                         * the month. We will retry in the next minute. This
 102                         * basically means that if the RTC must not drift
 103                         * by more than 1 minute in 11 minutes.
 104                         */
 105                        if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 106                                (new.tm_hour == 23 && new.tm_min == 59)))
 107                                err = rtc->ops->set_time(rtc->dev.parent,
 108                                                &new);
 109                }
 110        }
 111        else
 112                err = -EINVAL;
 113
 114        mutex_unlock(&rtc->ops_lock);
 115
 116        return err;
 117}
 118EXPORT_SYMBOL_GPL(rtc_set_mmss);
 119
 120static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 121{
 122        int err;
 123
 124        err = mutex_lock_interruptible(&rtc->ops_lock);
 125        if (err)
 126                return err;
 127
 128        if (rtc->ops == NULL)
 129                err = -ENODEV;
 130        else if (!rtc->ops->read_alarm)
 131                err = -EINVAL;
 132        else {
 133                memset(alarm, 0, sizeof(struct rtc_wkalrm));
 134                err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 135        }
 136
 137        mutex_unlock(&rtc->ops_lock);
 138        return err;
 139}
 140
 141int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 142{
 143        int err;
 144        struct rtc_time before, now;
 145        int first_time = 1;
 146        unsigned long t_now, t_alm;
 147        enum { none, day, month, year } missing = none;
 148        unsigned days;
 149
 150        /* The lower level RTC driver may return -1 in some fields,
 151         * creating invalid alarm->time values, for reasons like:
 152         *
 153         *   - The hardware may not be capable of filling them in;
 154         *     many alarms match only on time-of-day fields, not
 155         *     day/month/year calendar data.
 156         *
 157         *   - Some hardware uses illegal values as "wildcard" match
 158         *     values, which non-Linux firmware (like a BIOS) may try
 159         *     to set up as e.g. "alarm 15 minutes after each hour".
 160         *     Linux uses only oneshot alarms.
 161         *
 162         * When we see that here, we deal with it by using values from
 163         * a current RTC timestamp for any missing (-1) values.  The
 164         * RTC driver prevents "periodic alarm" modes.
 165         *
 166         * But this can be racey, because some fields of the RTC timestamp
 167         * may have wrapped in the interval since we read the RTC alarm,
 168         * which would lead to us inserting inconsistent values in place
 169         * of the -1 fields.
 170         *
 171         * Reading the alarm and timestamp in the reverse sequence
 172         * would have the same race condition, and not solve the issue.
 173         *
 174         * So, we must first read the RTC timestamp,
 175         * then read the RTC alarm value,
 176         * and then read a second RTC timestamp.
 177         *
 178         * If any fields of the second timestamp have changed
 179         * when compared with the first timestamp, then we know
 180         * our timestamp may be inconsistent with that used by
 181         * the low-level rtc_read_alarm_internal() function.
 182         *
 183         * So, when the two timestamps disagree, we just loop and do
 184         * the process again to get a fully consistent set of values.
 185         *
 186         * This could all instead be done in the lower level driver,
 187         * but since more than one lower level RTC implementation needs it,
 188         * then it's probably best best to do it here instead of there..
 189         */
 190
 191        /* Get the "before" timestamp */
 192        err = rtc_read_time(rtc, &before);
 193        if (err < 0)
 194                return err;
 195        do {
 196                if (!first_time)
 197                        memcpy(&before, &now, sizeof(struct rtc_time));
 198                first_time = 0;
 199
 200                /* get the RTC alarm values, which may be incomplete */
 201                err = rtc_read_alarm_internal(rtc, alarm);
 202                if (err)
 203                        return err;
 204
 205                /* full-function RTCs won't have such missing fields */
 206                if (rtc_valid_tm(&alarm->time) == 0)
 207                        return 0;
 208
 209                /* get the "after" timestamp, to detect wrapped fields */
 210                err = rtc_read_time(rtc, &now);
 211                if (err < 0)
 212                        return err;
 213
 214                /* note that tm_sec is a "don't care" value here: */
 215        } while (   before.tm_min   != now.tm_min
 216                 || before.tm_hour  != now.tm_hour
 217                 || before.tm_mon   != now.tm_mon
 218                 || before.tm_year  != now.tm_year);
 219
 220        /* Fill in the missing alarm fields using the timestamp; we
 221         * know there's at least one since alarm->time is invalid.
 222         */
 223        if (alarm->time.tm_sec == -1)
 224                alarm->time.tm_sec = now.tm_sec;
 225        if (alarm->time.tm_min == -1)
 226                alarm->time.tm_min = now.tm_min;
 227        if (alarm->time.tm_hour == -1)
 228                alarm->time.tm_hour = now.tm_hour;
 229
 230        /* For simplicity, only support date rollover for now */
 231        if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
 232                alarm->time.tm_mday = now.tm_mday;
 233                missing = day;
 234        }
 235        if ((unsigned)alarm->time.tm_mon >= 12) {
 236                alarm->time.tm_mon = now.tm_mon;
 237                if (missing == none)
 238                        missing = month;
 239        }
 240        if (alarm->time.tm_year == -1) {
 241                alarm->time.tm_year = now.tm_year;
 242                if (missing == none)
 243                        missing = year;
 244        }
 245
 246        /* with luck, no rollover is needed */
 247        rtc_tm_to_time(&now, &t_now);
 248        rtc_tm_to_time(&alarm->time, &t_alm);
 249        if (t_now < t_alm)
 250                goto done;
 251
 252        switch (missing) {
 253
 254        /* 24 hour rollover ... if it's now 10am Monday, an alarm that
 255         * that will trigger at 5am will do so at 5am Tuesday, which
 256         * could also be in the next month or year.  This is a common
 257         * case, especially for PCs.
 258         */
 259        case day:
 260                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 261                t_alm += 24 * 60 * 60;
 262                rtc_time_to_tm(t_alm, &alarm->time);
 263                break;
 264
 265        /* Month rollover ... if it's the 31th, an alarm on the 3rd will
 266         * be next month.  An alarm matching on the 30th, 29th, or 28th
 267         * may end up in the month after that!  Many newer PCs support
 268         * this type of alarm.
 269         */
 270        case month:
 271                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 272                do {
 273                        if (alarm->time.tm_mon < 11)
 274                                alarm->time.tm_mon++;
 275                        else {
 276                                alarm->time.tm_mon = 0;
 277                                alarm->time.tm_year++;
 278                        }
 279                        days = rtc_month_days(alarm->time.tm_mon,
 280                                        alarm->time.tm_year);
 281                } while (days < alarm->time.tm_mday);
 282                break;
 283
 284        /* Year rollover ... easy except for leap years! */
 285        case year:
 286                dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 287                do {
 288                        alarm->time.tm_year++;
 289                } while (rtc_valid_tm(&alarm->time) != 0);
 290                break;
 291
 292        default:
 293                dev_warn(&rtc->dev, "alarm rollover not handled\n");
 294        }
 295
 296done:
 297        return 0;
 298}
 299
 300int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 301{
 302        int err;
 303
 304        err = mutex_lock_interruptible(&rtc->ops_lock);
 305        if (err)
 306                return err;
 307        if (rtc->ops == NULL)
 308                err = -ENODEV;
 309        else if (!rtc->ops->read_alarm)
 310                err = -EINVAL;
 311        else {
 312                memset(alarm, 0, sizeof(struct rtc_wkalrm));
 313                alarm->enabled = rtc->aie_timer.enabled;
 314                alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
 315        }
 316        mutex_unlock(&rtc->ops_lock);
 317
 318        return err;
 319}
 320EXPORT_SYMBOL_GPL(rtc_read_alarm);
 321
 322static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 323{
 324        struct rtc_time tm;
 325        long now, scheduled;
 326        int err;
 327
 328        err = rtc_valid_tm(&alarm->time);
 329        if (err)
 330                return err;
 331        rtc_tm_to_time(&alarm->time, &scheduled);
 332
 333        /* Make sure we're not setting alarms in the past */
 334        err = __rtc_read_time(rtc, &tm);
 335        rtc_tm_to_time(&tm, &now);
 336        if (scheduled <= now)
 337                return -ETIME;
 338        /*
 339         * XXX - We just checked to make sure the alarm time is not
 340         * in the past, but there is still a race window where if
 341         * the is alarm set for the next second and the second ticks
 342         * over right here, before we set the alarm.
 343         */
 344
 345        if (!rtc->ops)
 346                err = -ENODEV;
 347        else if (!rtc->ops->set_alarm)
 348                err = -EINVAL;
 349        else
 350                err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
 351
 352        return err;
 353}
 354
 355int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 356{
 357        int err;
 358
 359        err = rtc_valid_tm(&alarm->time);
 360        if (err != 0)
 361                return err;
 362
 363        err = mutex_lock_interruptible(&rtc->ops_lock);
 364        if (err)
 365                return err;
 366        if (rtc->aie_timer.enabled) {
 367                rtc_timer_remove(rtc, &rtc->aie_timer);
 368        }
 369        rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 370        rtc->aie_timer.period = ktime_set(0, 0);
 371        if (alarm->enabled) {
 372                err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 373        }
 374        mutex_unlock(&rtc->ops_lock);
 375        return err;
 376}
 377EXPORT_SYMBOL_GPL(rtc_set_alarm);
 378
 379/* Called once per device from rtc_device_register */
 380int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 381{
 382        int err;
 383
 384        err = rtc_valid_tm(&alarm->time);
 385        if (err != 0)
 386                return err;
 387
 388        err = mutex_lock_interruptible(&rtc->ops_lock);
 389        if (err)
 390                return err;
 391
 392        rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
 393        rtc->aie_timer.period = ktime_set(0, 0);
 394        if (alarm->enabled) {
 395                rtc->aie_timer.enabled = 1;
 396                timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
 397        }
 398        mutex_unlock(&rtc->ops_lock);
 399        return err;
 400}
 401EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
 402
 403
 404
 405int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 406{
 407        int err = mutex_lock_interruptible(&rtc->ops_lock);
 408        if (err)
 409                return err;
 410
 411        if (rtc->aie_timer.enabled != enabled) {
 412                if (enabled)
 413                        err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
 414                else
 415                        rtc_timer_remove(rtc, &rtc->aie_timer);
 416        }
 417
 418        if (err)
 419                /* nothing */;
 420        else if (!rtc->ops)
 421                err = -ENODEV;
 422        else if (!rtc->ops->alarm_irq_enable)
 423                err = -EINVAL;
 424        else
 425                err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
 426
 427        mutex_unlock(&rtc->ops_lock);
 428        return err;
 429}
 430EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
 431
 432int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 433{
 434        int err = mutex_lock_interruptible(&rtc->ops_lock);
 435        if (err)
 436                return err;
 437
 438#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 439        if (enabled == 0 && rtc->uie_irq_active) {
 440                mutex_unlock(&rtc->ops_lock);
 441                return rtc_dev_update_irq_enable_emul(rtc, 0);
 442        }
 443#endif
 444        /* make sure we're changing state */
 445        if (rtc->uie_rtctimer.enabled == enabled)
 446                goto out;
 447
 448        if (rtc->uie_unsupported) {
 449                err = -EINVAL;
 450                goto out;
 451        }
 452
 453        if (enabled) {
 454                struct rtc_time tm;
 455                ktime_t now, onesec;
 456
 457                __rtc_read_time(rtc, &tm);
 458                onesec = ktime_set(1, 0);
 459                now = rtc_tm_to_ktime(tm);
 460                rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
 461                rtc->uie_rtctimer.period = ktime_set(1, 0);
 462                err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
 463        } else
 464                rtc_timer_remove(rtc, &rtc->uie_rtctimer);
 465
 466out:
 467        mutex_unlock(&rtc->ops_lock);
 468#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 469        /*
 470         * Enable emulation if the driver did not provide
 471         * the update_irq_enable function pointer or if returned
 472         * -EINVAL to signal that it has been configured without
 473         * interrupts or that are not available at the moment.
 474         */
 475        if (err == -EINVAL)
 476                err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 477#endif
 478        return err;
 479
 480}
 481EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
 482
 483
 484/**
 485 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
 486 * @rtc: pointer to the rtc device
 487 *
 488 * This function is called when an AIE, UIE or PIE mode interrupt
 489 * has occurred (or been emulated).
 490 *
 491 * Triggers the registered irq_task function callback.
 492 */
 493void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 494{
 495        unsigned long flags;
 496
 497        /* mark one irq of the appropriate mode */
 498        spin_lock_irqsave(&rtc->irq_lock, flags);
 499        rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
 500        spin_unlock_irqrestore(&rtc->irq_lock, flags);
 501
 502        /* call the task func */
 503        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 504        if (rtc->irq_task)
 505                rtc->irq_task->func(rtc->irq_task->private_data);
 506        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 507
 508        wake_up_interruptible(&rtc->irq_queue);
 509        kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 510}
 511
 512
 513/**
 514 * rtc_aie_update_irq - AIE mode rtctimer hook
 515 * @private: pointer to the rtc_device
 516 *
 517 * This functions is called when the aie_timer expires.
 518 */
 519void rtc_aie_update_irq(void *private)
 520{
 521        struct rtc_device *rtc = (struct rtc_device *)private;
 522        rtc_handle_legacy_irq(rtc, 1, RTC_AF);
 523}
 524
 525
 526/**
 527 * rtc_uie_update_irq - UIE mode rtctimer hook
 528 * @private: pointer to the rtc_device
 529 *
 530 * This functions is called when the uie_timer expires.
 531 */
 532void rtc_uie_update_irq(void *private)
 533{
 534        struct rtc_device *rtc = (struct rtc_device *)private;
 535        rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
 536}
 537
 538
 539/**
 540 * rtc_pie_update_irq - PIE mode hrtimer hook
 541 * @timer: pointer to the pie mode hrtimer
 542 *
 543 * This function is used to emulate PIE mode interrupts
 544 * using an hrtimer. This function is called when the periodic
 545 * hrtimer expires.
 546 */
 547enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
 548{
 549        struct rtc_device *rtc;
 550        ktime_t period;
 551        int count;
 552        rtc = container_of(timer, struct rtc_device, pie_timer);
 553
 554        period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
 555        count = hrtimer_forward_now(timer, period);
 556
 557        rtc_handle_legacy_irq(rtc, count, RTC_PF);
 558
 559        return HRTIMER_RESTART;
 560}
 561
 562/**
 563 * rtc_update_irq - Triggered when a RTC interrupt occurs.
 564 * @rtc: the rtc device
 565 * @num: how many irqs are being reported (usually one)
 566 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
 567 * Context: any
 568 */
 569void rtc_update_irq(struct rtc_device *rtc,
 570                unsigned long num, unsigned long events)
 571{
 572        schedule_work(&rtc->irqwork);
 573}
 574EXPORT_SYMBOL_GPL(rtc_update_irq);
 575
 576static int __rtc_match(struct device *dev, void *data)
 577{
 578        char *name = (char *)data;
 579
 580        if (strcmp(dev_name(dev), name) == 0)
 581                return 1;
 582        return 0;
 583}
 584
 585struct rtc_device *rtc_class_open(char *name)
 586{
 587        struct device *dev;
 588        struct rtc_device *rtc = NULL;
 589
 590        dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 591        if (dev)
 592                rtc = to_rtc_device(dev);
 593
 594        if (rtc) {
 595                if (!try_module_get(rtc->owner)) {
 596                        put_device(dev);
 597                        rtc = NULL;
 598                }
 599        }
 600
 601        return rtc;
 602}
 603EXPORT_SYMBOL_GPL(rtc_class_open);
 604
 605void rtc_class_close(struct rtc_device *rtc)
 606{
 607        module_put(rtc->owner);
 608        put_device(&rtc->dev);
 609}
 610EXPORT_SYMBOL_GPL(rtc_class_close);
 611
 612int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 613{
 614        int retval = -EBUSY;
 615
 616        if (task == NULL || task->func == NULL)
 617                return -EINVAL;
 618
 619        /* Cannot register while the char dev is in use */
 620        if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 621                return -EBUSY;
 622
 623        spin_lock_irq(&rtc->irq_task_lock);
 624        if (rtc->irq_task == NULL) {
 625                rtc->irq_task = task;
 626                retval = 0;
 627        }
 628        spin_unlock_irq(&rtc->irq_task_lock);
 629
 630        clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
 631
 632        return retval;
 633}
 634EXPORT_SYMBOL_GPL(rtc_irq_register);
 635
 636void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 637{
 638        spin_lock_irq(&rtc->irq_task_lock);
 639        if (rtc->irq_task == task)
 640                rtc->irq_task = NULL;
 641        spin_unlock_irq(&rtc->irq_task_lock);
 642}
 643EXPORT_SYMBOL_GPL(rtc_irq_unregister);
 644
 645static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
 646{
 647        /*
 648         * We always cancel the timer here first, because otherwise
 649         * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
 650         * when we manage to start the timer before the callback
 651         * returns HRTIMER_RESTART.
 652         *
 653         * We cannot use hrtimer_cancel() here as a running callback
 654         * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
 655         * would spin forever.
 656         */
 657        if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
 658                return -1;
 659
 660        if (enabled) {
 661                ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
 662
 663                hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
 664        }
 665        return 0;
 666}
 667
 668/**
 669 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
 670 * @rtc: the rtc device
 671 * @task: currently registered with rtc_irq_register()
 672 * @enabled: true to enable periodic IRQs
 673 * Context: any
 674 *
 675 * Note that rtc_irq_set_freq() should previously have been used to
 676 * specify the desired frequency of periodic IRQ task->func() callbacks.
 677 */
 678int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 679{
 680        int err = 0;
 681        unsigned long flags;
 682
 683retry:
 684        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 685        if (rtc->irq_task != NULL && task == NULL)
 686                err = -EBUSY;
 687        if (rtc->irq_task != task)
 688                err = -EACCES;
 689        if (!err) {
 690                if (rtc_update_hrtimer(rtc, enabled) < 0) {
 691                        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 692                        cpu_relax();
 693                        goto retry;
 694                }
 695                rtc->pie_enabled = enabled;
 696        }
 697        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 698        return err;
 699}
 700EXPORT_SYMBOL_GPL(rtc_irq_set_state);
 701
 702/**
 703 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
 704 * @rtc: the rtc device
 705 * @task: currently registered with rtc_irq_register()
 706 * @freq: positive frequency with which task->func() will be called
 707 * Context: any
 708 *
 709 * Note that rtc_irq_set_state() is used to enable or disable the
 710 * periodic IRQs.
 711 */
 712int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 713{
 714        int err = 0;
 715        unsigned long flags;
 716
 717        if (freq <= 0 || freq > RTC_MAX_FREQ)
 718                return -EINVAL;
 719retry:
 720        spin_lock_irqsave(&rtc->irq_task_lock, flags);
 721        if (rtc->irq_task != NULL && task == NULL)
 722                err = -EBUSY;
 723        if (rtc->irq_task != task)
 724                err = -EACCES;
 725        if (!err) {
 726                rtc->irq_freq = freq;
 727                if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
 728                        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 729                        cpu_relax();
 730                        goto retry;
 731                }
 732        }
 733        spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 734        return err;
 735}
 736EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
 737
 738/**
 739 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
 740 * @rtc rtc device
 741 * @timer timer being added.
 742 *
 743 * Enqueues a timer onto the rtc devices timerqueue and sets
 744 * the next alarm event appropriately.
 745 *
 746 * Sets the enabled bit on the added timer.
 747 *
 748 * Must hold ops_lock for proper serialization of timerqueue
 749 */
 750static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 751{
 752        timer->enabled = 1;
 753        timerqueue_add(&rtc->timerqueue, &timer->node);
 754        if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
 755                struct rtc_wkalrm alarm;
 756                int err;
 757                alarm.time = rtc_ktime_to_tm(timer->node.expires);
 758                alarm.enabled = 1;
 759                err = __rtc_set_alarm(rtc, &alarm);
 760                if (err == -ETIME)
 761                        schedule_work(&rtc->irqwork);
 762                else if (err) {
 763                        timerqueue_del(&rtc->timerqueue, &timer->node);
 764                        timer->enabled = 0;
 765                        return err;
 766                }
 767        }
 768        return 0;
 769}
 770
 771static void rtc_alarm_disable(struct rtc_device *rtc)
 772{
 773        if (!rtc->ops || !rtc->ops->alarm_irq_enable)
 774                return;
 775
 776        rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
 777}
 778
 779/**
 780 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
 781 * @rtc rtc device
 782 * @timer timer being removed.
 783 *
 784 * Removes a timer onto the rtc devices timerqueue and sets
 785 * the next alarm event appropriately.
 786 *
 787 * Clears the enabled bit on the removed timer.
 788 *
 789 * Must hold ops_lock for proper serialization of timerqueue
 790 */
 791static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 792{
 793        struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
 794        timerqueue_del(&rtc->timerqueue, &timer->node);
 795        timer->enabled = 0;
 796        if (next == &timer->node) {
 797                struct rtc_wkalrm alarm;
 798                int err;
 799                next = timerqueue_getnext(&rtc->timerqueue);
 800                if (!next) {
 801                        rtc_alarm_disable(rtc);
 802                        return;
 803                }
 804                alarm.time = rtc_ktime_to_tm(next->expires);
 805                alarm.enabled = 1;
 806                err = __rtc_set_alarm(rtc, &alarm);
 807                if (err == -ETIME)
 808                        schedule_work(&rtc->irqwork);
 809        }
 810}
 811
 812/**
 813 * rtc_timer_do_work - Expires rtc timers
 814 * @rtc rtc device
 815 * @timer timer being removed.
 816 *
 817 * Expires rtc timers. Reprograms next alarm event if needed.
 818 * Called via worktask.
 819 *
 820 * Serializes access to timerqueue via ops_lock mutex
 821 */
 822void rtc_timer_do_work(struct work_struct *work)
 823{
 824        struct rtc_timer *timer;
 825        struct timerqueue_node *next;
 826        ktime_t now;
 827        struct rtc_time tm;
 828
 829        struct rtc_device *rtc =
 830                container_of(work, struct rtc_device, irqwork);
 831
 832        mutex_lock(&rtc->ops_lock);
 833again:
 834        __rtc_read_time(rtc, &tm);
 835        now = rtc_tm_to_ktime(tm);
 836        while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 837                if (next->expires.tv64 > now.tv64)
 838                        break;
 839
 840                /* expire timer */
 841                timer = container_of(next, struct rtc_timer, node);
 842                timerqueue_del(&rtc->timerqueue, &timer->node);
 843                timer->enabled = 0;
 844                if (timer->task.func)
 845                        timer->task.func(timer->task.private_data);
 846
 847                /* Re-add/fwd periodic timers */
 848                if (ktime_to_ns(timer->period)) {
 849                        timer->node.expires = ktime_add(timer->node.expires,
 850                                                        timer->period);
 851                        timer->enabled = 1;
 852                        timerqueue_add(&rtc->timerqueue, &timer->node);
 853                }
 854        }
 855
 856        /* Set next alarm */
 857        if (next) {
 858                struct rtc_wkalrm alarm;
 859                int err;
 860                alarm.time = rtc_ktime_to_tm(next->expires);
 861                alarm.enabled = 1;
 862                err = __rtc_set_alarm(rtc, &alarm);
 863                if (err == -ETIME)
 864                        goto again;
 865        } else
 866                rtc_alarm_disable(rtc);
 867
 868        mutex_unlock(&rtc->ops_lock);
 869}
 870
 871
 872/* rtc_timer_init - Initializes an rtc_timer
 873 * @timer: timer to be intiialized
 874 * @f: function pointer to be called when timer fires
 875 * @data: private data passed to function pointer
 876 *
 877 * Kernel interface to initializing an rtc_timer.
 878 */
 879void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data)
 880{
 881        timerqueue_init(&timer->node);
 882        timer->enabled = 0;
 883        timer->task.func = f;
 884        timer->task.private_data = data;
 885}
 886
 887/* rtc_timer_start - Sets an rtc_timer to fire in the future
 888 * @ rtc: rtc device to be used
 889 * @ timer: timer being set
 890 * @ expires: time at which to expire the timer
 891 * @ period: period that the timer will recur
 892 *
 893 * Kernel interface to set an rtc_timer
 894 */
 895int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
 896                        ktime_t expires, ktime_t period)
 897{
 898        int ret = 0;
 899        mutex_lock(&rtc->ops_lock);
 900        if (timer->enabled)
 901                rtc_timer_remove(rtc, timer);
 902
 903        timer->node.expires = expires;
 904        timer->period = period;
 905
 906        ret = rtc_timer_enqueue(rtc, timer);
 907
 908        mutex_unlock(&rtc->ops_lock);
 909        return ret;
 910}
 911
 912/* rtc_timer_cancel - Stops an rtc_timer
 913 * @ rtc: rtc device to be used
 914 * @ timer: timer being set
 915 *
 916 * Kernel interface to cancel an rtc_timer
 917 */
 918int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
 919{
 920        int ret = 0;
 921        mutex_lock(&rtc->ops_lock);
 922        if (timer->enabled)
 923                rtc_timer_remove(rtc, timer);
 924        mutex_unlock(&rtc->ops_lock);
 925        return ret;
 926}
 927
 928
 929