/* * RTC subsystem, interface functions * * Copyright (C) 2005 Tower Technologies * Author: Alessandro Zummo <a.zummo@towertech.it> * * based on arch/arm/common/rtctime.c * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/rtc.h> #include <linux/log2.h> int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm) { int err; err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return -EBUSY; if (!rtc->ops) err = -ENODEV; else if (!rtc->ops->read_time) err = -EINVAL; else { memset(tm, 0, sizeof(struct rtc_time)); err = rtc->ops->read_time(rtc->dev.parent, tm); } mutex_unlock(&rtc->ops_lock); return err; } EXPORT_SYMBOL_GPL(rtc_read_time); int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm) { int err; err = rtc_valid_tm(tm); if (err != 0) return err; err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return -EBUSY; if (!rtc->ops) err = -ENODEV; else if (!rtc->ops->set_time) err = -EINVAL; else err = rtc->ops->set_time(rtc->dev.parent, tm); mutex_unlock(&rtc->ops_lock); return err; } EXPORT_SYMBOL_GPL(rtc_set_time); int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs) { int err; err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return -EBUSY; if (!rtc->ops) err = -ENODEV; else if (rtc->ops->set_mmss) err = rtc->ops->set_mmss(rtc->dev.parent, secs); else if (rtc->ops->read_time && rtc->ops->set_time) { struct rtc_time new, old; err = rtc->ops->read_time(rtc->dev.parent, &old); if (err == 0) { rtc_time_to_tm(secs, &new); /* * avoid writing when we're going to change the day of * the month. We will retry in the next minute. This * basically means that if the RTC must not drift * by more than 1 minute in 11 minutes. */ if (!((old.tm_hour == 23 && old.tm_min == 59) || (new.tm_hour == 23 && new.tm_min == 59))) err = rtc->ops->set_time(rtc->dev.parent, &new); } } else err = -EINVAL; mutex_unlock(&rtc->ops_lock); 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 -EBUSY; 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; /* The lower level RTC driver may not be capable of filling * in all fields of the rtc_time struct (eg. rtc-cmos), * and so might instead return -1 in some fields. * We deal with that here by grabbing a current RTC timestamp * and using values from that for any missing (-1) values. * * 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; if (!alarm->enabled) 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 || before.tm_isdst != now.tm_isdst); /* Fill in any missing alarm fields using the timestamp */ 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; if (alarm->time.tm_mday == -1) alarm->time.tm_mday = now.tm_mday; if (alarm->time.tm_mon == -1) alarm->time.tm_mon = now.tm_mon; if (alarm->time.tm_year == -1) alarm->time.tm_year = now.tm_year; return 0; } EXPORT_SYMBOL_GPL(rtc_read_alarm); int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) { int err; err = rtc_valid_tm(&alarm->time); if (err != 0) return err; err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return -EBUSY; if (!rtc->ops) err = -ENODEV; else if (!rtc->ops->set_alarm) err = -EINVAL; else err = rtc->ops->set_alarm(rtc->dev.parent, alarm); mutex_unlock(&rtc->ops_lock); return err; } EXPORT_SYMBOL_GPL(rtc_set_alarm); /** * rtc_update_irq - report RTC periodic, alarm, and/or update irqs * @rtc: the rtc device * @num: how many irqs are being reported (usually one) * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF * Context: in_interrupt(), irqs blocked */ void rtc_update_irq(struct rtc_device *rtc, unsigned long num, unsigned long events) { spin_lock(&rtc->irq_lock); rtc->irq_data = (rtc->irq_data + (num << 8)) | events; spin_unlock(&rtc->irq_lock); spin_lock(&rtc->irq_task_lock); if (rtc->irq_task) rtc->irq_task->func(rtc->irq_task->private_data); spin_unlock(&rtc->irq_task_lock); wake_up_interruptible(&rtc->irq_queue); kill_fasync(&rtc->async_queue, SIGIO, POLL_IN); } EXPORT_SYMBOL_GPL(rtc_update_irq); struct rtc_device *rtc_class_open(char *name) { struct device *dev; struct rtc_device *rtc = NULL; down(&rtc_class->sem); list_for_each_entry(dev, &rtc_class->devices, node) { if (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 0) { dev = get_device(dev); if (dev) rtc = to_rtc_device(dev); break; } } if (rtc) { if (!try_module_get(rtc->owner)) { put_device(dev); rtc = NULL; } } up(&rtc_class->sem); return rtc; } EXPORT_SYMBOL_GPL(rtc_class_open); void rtc_class_close(struct rtc_device *rtc) { module_put(rtc->owner); put_device(&rtc->dev); } EXPORT_SYMBOL_GPL(rtc_class_close); int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) { int retval = -EBUSY; if (task == NULL || task->func == NULL) return -EINVAL; /* Cannot register while the char dev is in use */ if (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags)) return -EBUSY; spin_lock_irq(&rtc->irq_task_lock); if (rtc->irq_task == NULL) { rtc->irq_task = task; retval = 0; } spin_unlock_irq(&rtc->irq_task_lock); clear_bit(RTC_DEV_BUSY, &rtc->flags); return retval; } EXPORT_SYMBOL_GPL(rtc_irq_register); void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task) { spin_lock_irq(&rtc->irq_task_lock); if (rtc->irq_task == task) rtc->irq_task = NULL; spin_unlock_irq(&rtc->irq_task_lock); } EXPORT_SYMBOL_GPL(rtc_irq_unregister); /** * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs * @rtc: the rtc device * @task: currently registered with rtc_irq_register() * @enabled: true to enable periodic IRQs * Context: any * * Note that rtc_irq_set_freq() should previously have been used to * specify the desired frequency of periodic IRQ task->func() callbacks. */ int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled) { int err = 0; unsigned long flags; if (rtc->ops->irq_set_state == NULL) return -ENXIO; spin_lock_irqsave(&rtc->irq_task_lock, flags); if (rtc->irq_task != NULL && task == NULL) err = -EBUSY; if (rtc->irq_task != task) err = -EACCES; spin_unlock_irqrestore(&rtc->irq_task_lock, flags); if (err == 0) err = rtc->ops->irq_set_state(rtc->dev.parent, enabled); return err; } EXPORT_SYMBOL_GPL(rtc_irq_set_state); /** * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ * @rtc: the rtc device * @task: currently registered with rtc_irq_register() * @freq: positive frequency with which task->func() will be called * Context: any * * Note that rtc_irq_set_state() is used to enable or disable the * periodic IRQs. */ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq) { int err = 0; unsigned long flags; if (rtc->ops->irq_set_freq == NULL) return -ENXIO; if (!is_power_of_2(freq)) return -EINVAL; spin_lock_irqsave(&rtc->irq_task_lock, flags); if (rtc->irq_task != NULL && task == NULL) err = -EBUSY; if (rtc->irq_task != task) err = -EACCES; spin_unlock_irqrestore(&rtc->irq_task_lock, flags); if (err == 0) { err = rtc->ops->irq_set_freq(rtc->dev.parent, freq); if (err == 0) rtc->irq_freq = freq; } return err; } EXPORT_SYMBOL_GPL(rtc_irq_set_freq);