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linux
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drivers
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rtc
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interface.c
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526 lines (450 loc) · 13 KB
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linux
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drivers
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interface.c
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/* * 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 err; 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 err; if (!rtc->ops) err = -ENODEV; else if (rtc->ops->set_time) err = rtc->ops->set_time(rtc->dev.parent, tm); else if (rtc->ops->set_mmss) { unsigned long secs; err = rtc_tm_to_time(tm, &secs); if (err == 0) err = rtc->ops->set_mmss(rtc->dev.parent, secs); } else err = -EINVAL; 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 err; 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 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; if (!alarm->enabled) return 0; /* 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 = now.tm_mday; missing = day; } if (alarm->time.tm_mon == -1) { 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; } 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 err; 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); int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled) { int err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return err; if (!rtc->ops) err = -ENODEV; else if (!rtc->ops->alarm_irq_enable) err = -EINVAL; else err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled); mutex_unlock(&rtc->ops_lock); return err; } EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable); int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled) { int err = mutex_lock_interruptible(&rtc->ops_lock); if (err) return err; #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL if (enabled == 0 && rtc->uie_irq_active) { mutex_unlock(&rtc->ops_lock); return rtc_dev_update_irq_enable_emul(rtc, enabled); } #endif if (!rtc->ops) err = -ENODEV; else if (!rtc->ops->update_irq_enable) err = -EINVAL; else err = rtc->ops->update_irq_enable(rtc->dev.parent, enabled); mutex_unlock(&rtc->ops_lock); #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL /* * Enable emulation if the driver did not provide * the update_irq_enable function pointer or if returned * -EINVAL to signal that it has been configured without * interrupts or that are not available at the moment. */ if (err == -EINVAL) err = rtc_dev_update_irq_enable_emul(rtc, enabled); #endif return err; } EXPORT_SYMBOL_GPL(rtc_update_irq_enable); /** * 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); static int __rtc_match(struct device *dev, void *data) { char *name = (char *)data; if (strcmp(dev_name(dev), name) == 0) return 1; return 0; } struct rtc_device *rtc_class_open(char *name) { struct device *dev; struct rtc_device *rtc = NULL; dev = class_find_device(rtc_class, NULL, name, __rtc_match); if (dev) rtc = to_rtc_device(dev); if (rtc) { if (!try_module_get(rtc->owner)) { put_device(dev); rtc = NULL; } } 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_lock(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_unlock(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; 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);
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