diff options
Diffstat (limited to 'drivers/rtc/interface.c')
| -rw-r--r-- | drivers/rtc/interface.c | 329 |
1 files changed, 294 insertions, 35 deletions
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index cb2f0728fd70..72c5cdbe0791 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -13,6 +13,7 @@ #include <linux/rtc.h> #include <linux/sched.h> +#include <linux/module.h> #include <linux/log2.h> #include <linux/workqueue.h> @@ -72,6 +73,8 @@ int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm) err = -EINVAL; mutex_unlock(&rtc->ops_lock); + /* A timer might have just expired */ + schedule_work(&rtc->irqwork); return err; } EXPORT_SYMBOL_GPL(rtc_set_time); @@ -106,16 +109,198 @@ int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs) err = rtc->ops->set_time(rtc->dev.parent, &new); } - } - else + } else { err = -EINVAL; + } mutex_unlock(&rtc->ops_lock); + /* A timer might have just expired */ + schedule_work(&rtc->irqwork); return err; } EXPORT_SYMBOL_GPL(rtc_set_mmss); +static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm) +{ + int err; + + err = mutex_lock_interruptible(&rtc->ops_lock); + if (err) + return err; + + if (rtc->ops == NULL) + err = -ENODEV; + else if (!rtc->ops->read_alarm) + err = -EINVAL; + else { + memset(alarm, 0, sizeof(struct rtc_wkalrm)); + err = rtc->ops->read_alarm(rtc->dev.parent, alarm); + } + + mutex_unlock(&rtc->ops_lock); + return err; +} + +int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) +{ + int err; + struct rtc_time before, now; + int first_time = 1; + unsigned long t_now, t_alm; + enum { none, day, month, year } missing = none; + unsigned days; + + /* The lower level RTC driver may return -1 in some fields, + * creating invalid alarm->time values, for reasons like: + * + * - The hardware may not be capable of filling them in; + * many alarms match only on time-of-day fields, not + * day/month/year calendar data. + * + * - Some hardware uses illegal values as "wildcard" match + * values, which non-Linux firmware (like a BIOS) may try + * to set up as e.g. "alarm 15 minutes after each hour". + * Linux uses only oneshot alarms. + * + * When we see that here, we deal with it by using values from + * a current RTC timestamp for any missing (-1) values. The + * RTC driver prevents "periodic alarm" modes. + * + * But this can be racey, because some fields of the RTC timestamp + * may have wrapped in the interval since we read the RTC alarm, + * which would lead to us inserting inconsistent values in place + * of the -1 fields. + * + * Reading the alarm and timestamp in the reverse sequence + * would have the same race condition, and not solve the issue. + * + * So, we must first read the RTC timestamp, + * then read the RTC alarm value, + * and then read a second RTC timestamp. + * + * If any fields of the second timestamp have changed + * when compared with the first timestamp, then we know + * our timestamp may be inconsistent with that used by + * the low-level rtc_read_alarm_internal() function. + * + * So, when the two timestamps disagree, we just loop and do + * the process again to get a fully consistent set of values. + * + * This could all instead be done in the lower level driver, + * but since more than one lower level RTC implementation needs it, + * then it's probably best best to do it here instead of there.. + */ + + /* Get the "before" timestamp */ + err = rtc_read_time(rtc, &before); + if (err < 0) + return err; + do { + if (!first_time) + memcpy(&before, &now, sizeof(struct rtc_time)); + first_time = 0; + + /* get the RTC alarm values, which may be incomplete */ + err = rtc_read_alarm_internal(rtc, alarm); + if (err) + return err; + + /* full-function RTCs won't have such missing fields */ + if (rtc_valid_tm(&alarm->time) == 0) + return 0; + + /* get the "after" timestamp, to detect wrapped fields */ + err = rtc_read_time(rtc, &now); + if (err < 0) + return err; + + /* note that tm_sec is a "don't care" value here: */ + } while ( before.tm_min != now.tm_min + || before.tm_hour != now.tm_hour + || before.tm_mon != now.tm_mon + || before.tm_year != now.tm_year); + + /* Fill in the missing alarm fields using the timestamp; we + * know there's at least one since alarm->time is invalid. + */ + if (alarm->time.tm_sec == -1) + alarm->time.tm_sec = now.tm_sec; + if (alarm->time.tm_min == -1) + alarm->time.tm_min = now.tm_min; + if (alarm->time.tm_hour == -1) + alarm->time.tm_hour = now.tm_hour; + + /* For simplicity, only support date rollover for now */ + if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) { + alarm->time.tm_mday = now.tm_mday; + missing = day; + } + if ((unsigned)alarm->time.tm_mon >= 12) { + alarm->time.tm_mon = now.tm_mon; + if (missing == none) + missing = month; + } + if (alarm->time.tm_year == -1) { + alarm->time.tm_year = now.tm_year; + if (missing == none) + missing = year; + } + + /* with luck, no rollover is needed */ + rtc_tm_to_time(&now, &t_now); + rtc_tm_to_time(&alarm->time, &t_alm); + if (t_now < t_alm) + goto done; + + switch (missing) { + + /* 24 hour rollover ... if it's now 10am Monday, an alarm that + * that will trigger at 5am will do so at 5am Tuesday, which + * could also be in the next month or year. This is a common + * case, especially for PCs. + */ + case day: + dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day"); + t_alm += 24 * 60 * 60; + rtc_time_to_tm(t_alm, &alarm->time); + break; + + /* Month rollover ... if it's the 31th, an alarm on the 3rd will + * be next month. An alarm matching on the 30th, 29th, or 28th + * may end up in the month after that! Many newer PCs support + * this type of alarm. + */ + case month: + dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month"); + do { + if (alarm->time.tm_mon < 11) + alarm->time.tm_mon++; + else { + alarm->time.tm_mon = 0; + alarm->time.tm_year++; + } + days = rtc_month_days(alarm->time.tm_mon, + alarm->time.tm_year); + } while (days < alarm->time.tm_mday); + break; + + /* Year rollover ... easy except for leap years! */ + case year: + dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year"); + do { + alarm->time.tm_year++; + } while (rtc_valid_tm(&alarm->time) != 0); + break; + + default: + dev_warn(&rtc->dev, "alarm rollover not handled\n"); + } + +done: + return 0; +} + int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) { int err; @@ -138,7 +323,7 @@ int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) } EXPORT_SYMBOL_GPL(rtc_read_alarm); -int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) +static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) { struct rtc_time tm; long now, scheduled; @@ -182,19 +367,54 @@ int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return err; - if (rtc->aie_timer.enabled) { + if (rtc->aie_timer.enabled) rtc_timer_remove(rtc, &rtc->aie_timer); - } + rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time); rtc->aie_timer.period = ktime_set(0, 0); - if (alarm->enabled) { + if (alarm->enabled) err = rtc_timer_enqueue(rtc, &rtc->aie_timer); - } + mutex_unlock(&rtc->ops_lock); return err; } EXPORT_SYMBOL_GPL(rtc_set_alarm); +/* Called once per device from rtc_device_register */ +int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) +{ + int err; + struct rtc_time now; + + err = rtc_valid_tm(&alarm->time); + if (err != 0) + return err; + + err = rtc_read_time(rtc, &now); + if (err) + return err; + + err = mutex_lock_interruptible(&rtc->ops_lock); + if (err) + return err; + + rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time); + rtc->aie_timer.period = ktime_set(0, 0); + + /* Alarm has to be enabled & in the futrure for us to enqueue it */ + if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 < + rtc->aie_timer.node.expires.tv64)) { + + rtc->aie_timer.enabled = 1; + timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node); + } + mutex_unlock(&rtc->ops_lock); + return err; +} +EXPORT_SYMBOL_GPL(rtc_initialize_alarm); + + + int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled) { int err = mutex_lock_interruptible(&rtc->ops_lock); @@ -238,6 +458,11 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled) if (rtc->uie_rtctimer.enabled == enabled) goto out; + if (rtc->uie_unsupported) { + err = -EINVAL; + goto out; + } + if (enabled) { struct rtc_time tm; ktime_t now, onesec; @@ -274,7 +499,7 @@ EXPORT_SYMBOL_GPL(rtc_update_irq_enable); * @rtc: pointer to the rtc device * * This function is called when an AIE, UIE or PIE mode interrupt - * has occured (or been emulated). + * has occurred (or been emulated). * * Triggers the registered irq_task function callback. */ @@ -357,20 +582,21 @@ enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer) void rtc_update_irq(struct rtc_device *rtc, unsigned long num, unsigned long events) { + pm_stay_awake(rtc->dev.parent); schedule_work(&rtc->irqwork); } EXPORT_SYMBOL_GPL(rtc_update_irq); -static int __rtc_match(struct device *dev, void *data) +static int __rtc_match(struct device *dev, const void *data) { - char *name = (char *)data; + const char *name = data; if (strcmp(dev_name(dev), name) == 0) return 1; return 0; } -struct rtc_device *rtc_class_open(char *name) +struct rtc_device *rtc_class_open(const char *name) { struct device *dev; struct rtc_device *rtc = NULL; @@ -430,6 +656,29 @@ void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task) } EXPORT_SYMBOL_GPL(rtc_irq_unregister); +static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled) +{ + /* + * We always cancel the timer here first, because otherwise + * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK); + * when we manage to start the timer before the callback + * returns HRTIMER_RESTART. + * + * We cannot use hrtimer_cancel() here as a running callback + * could be blocked on rtc->irq_task_lock and hrtimer_cancel() + * would spin forever. + */ + if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0) + return -1; + + if (enabled) { + ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq); + + hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL); + } + return 0; +} + /** * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs * @rtc: the rtc device @@ -445,21 +694,21 @@ int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled int err = 0; unsigned long flags; +retry: spin_lock_irqsave(&rtc->irq_task_lock, flags); if (rtc->irq_task != NULL && task == NULL) err = -EBUSY; - if (rtc->irq_task != task) + else if (rtc->irq_task != task) err = -EACCES; - - if (enabled) { - ktime_t period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq); - hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL); - } else { - hrtimer_cancel(&rtc->pie_timer); + else { + if (rtc_update_hrtimer(rtc, enabled) < 0) { + spin_unlock_irqrestore(&rtc->irq_task_lock, flags); + cpu_relax(); + goto retry; + } + rtc->pie_enabled = enabled; } - rtc->pie_enabled = enabled; spin_unlock_irqrestore(&rtc->irq_task_lock, flags); - return err; } EXPORT_SYMBOL_GPL(rtc_irq_set_state); @@ -479,22 +728,20 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq) int err = 0; unsigned long flags; - if (freq <= 0) + if (freq <= 0 || freq > RTC_MAX_FREQ) return -EINVAL; - +retry: spin_lock_irqsave(&rtc->irq_task_lock, flags); if (rtc->irq_task != NULL && task == NULL) err = -EBUSY; - if (rtc->irq_task != task) + else if (rtc->irq_task != task) err = -EACCES; - if (err == 0) { + else { rtc->irq_freq = freq; - if (rtc->pie_enabled) { - ktime_t period; - hrtimer_cancel(&rtc->pie_timer); - period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq); - hrtimer_start(&rtc->pie_timer, period, - HRTIMER_MODE_REL); + if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) { + spin_unlock_irqrestore(&rtc->irq_task_lock, flags); + cpu_relax(); + goto retry; } } spin_unlock_irqrestore(&rtc->irq_task_lock, flags); @@ -535,6 +782,14 @@ static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer) return 0; } +static void rtc_alarm_disable(struct rtc_device *rtc) +{ + if (!rtc->ops || !rtc->ops->alarm_irq_enable) + return; + + rtc->ops->alarm_irq_enable(rtc->dev.parent, false); +} + /** * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue * @rtc rtc device @@ -556,8 +811,10 @@ static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer) struct rtc_wkalrm alarm; int err; next = timerqueue_getnext(&rtc->timerqueue); - if (!next) + if (!next) { + rtc_alarm_disable(rtc); return; + } alarm.time = rtc_ktime_to_tm(next->expires); alarm.enabled = 1; err = __rtc_set_alarm(rtc, &alarm); @@ -588,6 +845,7 @@ void rtc_timer_do_work(struct work_struct *work) mutex_lock(&rtc->ops_lock); again: + pm_relax(rtc->dev.parent); __rtc_read_time(rtc, &tm); now = rtc_tm_to_ktime(tm); while ((next = timerqueue_getnext(&rtc->timerqueue))) { @@ -619,7 +877,8 @@ again: err = __rtc_set_alarm(rtc, &alarm); if (err == -ETIME) goto again; - } + } else + rtc_alarm_disable(rtc); mutex_unlock(&rtc->ops_lock); } @@ -632,7 +891,7 @@ again: * * Kernel interface to initializing an rtc_timer. */ -void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data) +void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data) { timerqueue_init(&timer->node); timer->enabled = 0; @@ -648,7 +907,7 @@ void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data) * * Kernel interface to set an rtc_timer */ -int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer, +int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer, ktime_t expires, ktime_t period) { int ret = 0; @@ -671,7 +930,7 @@ int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer, * * Kernel interface to cancel an rtc_timer */ -int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer) +int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer) { int ret = 0; mutex_lock(&rtc->ops_lock); |