From f4c42213062170ddfcc706b3c5ed19f47517c253 Mon Sep 17 00:00:00 2001
From: Michael Sevakis <jethead71@rockbox.org>
Date: Thu, 26 Jan 2017 21:08:55 -0500
Subject: Convert i.MX31 and AMS target to use RTC interrupt

Instead of checking ticks, set a sticky dirty flag that indicates
that the RTC needs to be read. This gives a timely update and more
accurate readout without actually reading the RTC until it changes.
The implementation should atomically read the flag and clear it.
Setting the flag would typically happen in an RTC tick ISR.

Change-Id: I6fd325f22845029a485c502c884812d3676026ea
---
 firmware/common/timefuncs.c | 45 +++++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 12 deletions(-)

(limited to 'firmware/common/timefuncs.c')

diff --git a/firmware/common/timefuncs.c b/firmware/common/timefuncs.c
index c8819ea76e..50addad27a 100644
--- a/firmware/common/timefuncs.c
+++ b/firmware/common/timefuncs.c
@@ -24,13 +24,21 @@
 
 #include "kernel.h"
 #include "rtc.h"
+#ifdef HAVE_RTC_IRQ
+#include "rtc-target.h"
+#endif
 #include "timefuncs.h"
 #include "debug.h"
 
 static struct tm tm;
 
 #if !CONFIG_RTC
-static void fill_default_tm(struct tm *tm)
+static inline bool rtc_dirty(void)
+{
+    return true;
+}
+
+static inline int rtc_read_datetime(struct tm *tm)
 {
     tm->tm_sec = 0;
     tm->tm_min = 0;
@@ -38,9 +46,9 @@ static void fill_default_tm(struct tm *tm)
     tm->tm_mday = 1;
     tm->tm_mon = 0;
     tm->tm_year = 70;
-    tm->tm_wday = 1;
-    tm->tm_yday = 0; /* Not implemented for now */
-    tm->tm_isdst = -1; /* Not implemented for now */
+    tm->tm_wday = 4;
+    tm->tm_yday = 0;
+    return 1;
 }
 #endif /* !CONFIG_RTC */
 
@@ -58,24 +66,37 @@ bool valid_time(const struct tm *tm)
     else
         return true;
 }
-#endif /* CONFIG_RTC */
 
-struct tm *get_time(void)
+/* Don't read the RTC more than once per second
+ * returns true if the rtc needs to be read
+ * targets may override with their own implementation
+ */
+#ifndef HAVE_RTC_IRQ
+static inline bool rtc_dirty(void)
 {
-#if CONFIG_RTC
     static long timeout = 0;
 
     /* Don't read the RTC more than once per second */
     if (TIME_AFTER(current_tick, timeout))
     {
-        /* Once per second, 1/10th of a second off */
-        timeout = HZ * (current_tick / HZ + 1) + HZ / 5;
+        /* Once per second, 1/5th of a second off */
+        timeout = current_tick / HZ * HZ + 6*HZ / 5;
+        return true;
+    }
+
+    return false;
+}
+#endif /* HAVE_RTC_IRQ */
+#endif /* CONFIG_RTC */
+
+struct tm *get_time(void)
+{
+    if (rtc_dirty())
+    {
         rtc_read_datetime(&tm);
         tm.tm_isdst = -1; /* Not implemented for now */
     }
-#else /* No RTC */
-    fill_default_tm(&tm);
-#endif /* RTC */
+
     return &tm;
 }
 
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