1 files changed, 237 insertions, 26 deletions

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 90384b9f6b2c..8ec6b069a7f5 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -16,6 +16,9 @@
 #include <linux/log2.h>
 #include <linux/workqueue.h>
 
+static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
+static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
+
 static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
 {
         int err;
@@ -113,6 +116,186 @@ int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
 }
 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 = 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;
+}
+
 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
         int err;
@@ -120,12 +303,18 @@ int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
         err = mutex_lock_interruptible(&rtc->ops_lock);
         if (err)
                 return err;
-        alarm->enabled = rtc->aie_timer.enabled;
-        if (alarm->enabled)
+        if (rtc->ops == NULL)
+                err = -ENODEV;
+        else if (!rtc->ops->read_alarm)
+                err = -EINVAL;
+        else {
+                memset(alarm, 0, sizeof(struct rtc_wkalrm));
+                alarm->enabled = rtc->aie_timer.enabled;
                 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
+        }
         mutex_unlock(&rtc->ops_lock);
 
-        return 0;
+        return err;
 }
 EXPORT_SYMBOL_GPL(rtc_read_alarm);
 
@@ -175,16 +364,14 @@ int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
                 return err;
         if (rtc->aie_timer.enabled) {
                 rtc_timer_remove(rtc, &rtc->aie_timer);
-                rtc->aie_timer.enabled = 0;
         }
         rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
         rtc->aie_timer.period = ktime_set(0, 0);
         if (alarm->enabled) {
-                rtc->aie_timer.enabled = 1;
-                rtc_timer_enqueue(rtc, &rtc->aie_timer);
+                err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
         }
         mutex_unlock(&rtc->ops_lock);
-        return 0;
+        return err;
 }
 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 
@@ -195,16 +382,15 @@ int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
                 return err;
 
         if (rtc->aie_timer.enabled != enabled) {
-                if (enabled) {
-                        rtc->aie_timer.enabled = 1;
-                        rtc_timer_enqueue(rtc, &rtc->aie_timer);
-                } else {
+                if (enabled)
+                        err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
+                else
                         rtc_timer_remove(rtc, &rtc->aie_timer);
-                        rtc->aie_timer.enabled = 0;
-                }
         }
 
-        if (!rtc->ops)
+        if (err)
+                /* nothing */;
+        else if (!rtc->ops)
                 err = -ENODEV;
         else if (!rtc->ops->alarm_irq_enable)
                 err = -EINVAL;
@@ -222,6 +408,12 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
         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, 0);
+        }
+#endif
         /* make sure we're changing state */
         if (rtc->uie_rtctimer.enabled == enabled)
                 goto out;
@@ -235,15 +427,22 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
                 now = rtc_tm_to_ktime(tm);
                 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
                 rtc->uie_rtctimer.period = ktime_set(1, 0);
-                rtc->uie_rtctimer.enabled = 1;
-                rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
-        } else {
+                err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
+        } else
                 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
-                rtc->uie_rtctimer.enabled = 0;
-        }
 
 out:
         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;
 
 }
@@ -259,7 +458,7 @@ EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
  *
  * Triggers the registered irq_task function callback.
  */
-static void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
+void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
 {
         unsigned long flags;
 
@@ -460,6 +659,9 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
         int err = 0;
         unsigned long flags;
 
+        if (freq <= 0)
+                return -EINVAL;
+
         spin_lock_irqsave(&rtc->irq_task_lock, flags);
         if (rtc->irq_task != NULL && task == NULL)
                 err = -EBUSY;
@@ -488,10 +690,13 @@ EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
  * Enqueues a timer onto the rtc devices timerqueue and sets
  * the next alarm event appropriately.
  *
+ * Sets the enabled bit on the added timer.
+ *
  * Must hold ops_lock for proper serialization of timerqueue
  */
-void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
+static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
 {
+        timer->enabled = 1;
         timerqueue_add(&rtc->timerqueue, &timer->node);
         if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
                 struct rtc_wkalrm alarm;
@@ -501,7 +706,13 @@ void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
                 err = __rtc_set_alarm(rtc, &alarm);
                 if (err == -ETIME)
                         schedule_work(&rtc->irqwork);
+                else if (err) {
+                        timerqueue_del(&rtc->timerqueue, &timer->node);
+                        timer->enabled = 0;
+                        return err;
+                }
         }
+        return 0;
 }
 
 /**
@@ -512,13 +723,15 @@ void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
  * Removes a timer onto the rtc devices timerqueue and sets
  * the next alarm event appropriately.
  *
+ * Clears the enabled bit on the removed timer.
+ *
  * Must hold ops_lock for proper serialization of timerqueue
  */
-void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
+static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
 {
         struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
         timerqueue_del(&rtc->timerqueue, &timer->node);
-
+        timer->enabled = 0;
         if (next == &timer->node) {
                 struct rtc_wkalrm alarm;
                 int err;
@@ -626,8 +839,7 @@ int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
         timer->node.expires = expires;
         timer->period = period;
 
-        timer->enabled = 1;
-        rtc_timer_enqueue(rtc, timer);
+        ret = rtc_timer_enqueue(rtc, timer);
 
         mutex_unlock(&rtc->ops_lock);
         return ret;
@@ -645,7 +857,6 @@ int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
         mutex_lock(&rtc->ops_lock);
         if (timer->enabled)
                 rtc_timer_remove(rtc, timer);
-        timer->enabled = 0;
         mutex_unlock(&rtc->ops_lock);
         return ret;
 }