From da3c3bfa98e7cf81010a476b0b6ceba4c936f417 Mon Sep 17 00:00:00 2001
From: Gabe Black <gblack@eecs.umich.edu>
Date: Thu, 20 Aug 2009 00:42:43 -0700
Subject: X86: Make the real time clock actually keep track of time.

---
 src/dev/mc146818.cc | 96 ++++++++++++++++++++++++++++++++++++++++++-----------
 src/dev/mc146818.hh | 26 +++++++++++++++
 2 files changed, 103 insertions(+), 19 deletions(-)

(limited to 'src')

diff --git a/src/dev/mc146818.cc b/src/dev/mc146818.cc
index 2ee5dbaaa..8d289a416 100644
--- a/src/dev/mc146818.cc
+++ b/src/dev/mc146818.cc
@@ -43,28 +43,20 @@
 
 using namespace std;
 
-MC146818::MC146818(EventManager *em, const string &n, const struct tm time,
-                   bool bcd, Tick frequency)
-    : EventManager(em), _name(n), event(this, frequency)
+static uint8_t
+bcdize(uint8_t val)
 {
-    memset(clock_data, 0, sizeof(clock_data));
-    stat_regA = RTCA_32768HZ | RTCA_1024HZ;
-    stat_regB = RTCB_PRDC_IE | RTCB_24HR;
-    if (!bcd)
-        stat_regB |= RTCB_BIN;
+    uint8_t result;
+    result = val % 10;
+    result += (val / 10) << 4;
+    return result;
+}
 
+void
+MC146818::setTime(const struct tm time)
+{
+    curTime = time;
     year = time.tm_year;
-
-    if (bcd) {
-        // The datasheet says that the year field can be either BCD or
-        // years since 1900.  Linux seems to be happy with years since
-        // 1900.
-        year = year % 100;
-        int tens = year / 10;
-        int ones = year % 10;
-        year = (tens << 4) + ones;
-    }
-
     // Unix is 0-11 for month, data seet says start at 1
     mon = time.tm_mon + 1;
     mday = time.tm_mday;
@@ -75,6 +67,30 @@ MC146818::MC146818(EventManager *em, const string &n, const struct tm time,
     // Datasheet says 1 is sunday
     wday = time.tm_wday + 1;
 
+    if (!(stat_regB & RTCB_BIN)) {
+        // The datasheet says that the year field can be either BCD or
+        // years since 1900.  Linux seems to be happy with years since
+        // 1900.
+        year = bcdize(year % 100);
+        mon = bcdize(mon);
+        mday = bcdize(mday);
+        hour = bcdize(hour);
+        min = bcdize(min);
+        sec = bcdize(sec);
+    }
+}
+
+MC146818::MC146818(EventManager *em, const string &n, const struct tm time,
+                   bool bcd, Tick frequency)
+    : EventManager(em), _name(n), event(this, frequency), tickEvent(this)
+{
+    memset(clock_data, 0, sizeof(clock_data));
+    stat_regA = RTCA_32768HZ | RTCA_1024HZ;
+    stat_regB = RTCB_PRDC_IE | RTCB_24HR;
+    if (!bcd)
+        stat_regB |= RTCB_BIN;
+
+    setTime(time);
     DPRINTFN("Real-time clock set to %s", asctime(&time));
 }
 
@@ -141,6 +157,34 @@ MC146818::readData(uint8_t addr)
     }
 }
 
+static time_t
+mkutctime(struct tm *time)
+{
+    time_t ret;
+    char *tz;
+
+    tz = getenv("TZ");
+    setenv("TZ", "", 1);
+    tzset();
+    ret = mktime(time);
+    if (tz)
+        setenv("TZ", tz, 1);
+    else
+        unsetenv("TZ");
+    tzset();
+    return ret;
+}
+
+void
+MC146818::tickClock()
+{
+    if (stat_regB & RTCB_NO_UPDT)
+        return;
+    time_t calTime = mkutctime(&curTime);
+    calTime++;
+    setTime(*gmtime(&calTime));
+}
+
 void
 MC146818::serialize(const string &base, ostream &os)
 {
@@ -190,3 +234,17 @@ MC146818::RTCEvent::description() const
 {
     return "RTC interrupt";
 }
+
+void
+MC146818::RTCTickEvent::process()
+{
+    DPRINTF(MC146818, "RTC clock tick\n");
+    parent->schedule(this, curTick + Clock::Int::s);
+    parent->tickClock();
+}
+
+const char *
+MC146818::RTCTickEvent::description() const
+{
+    return "RTC clock tick";
+}
diff --git a/src/dev/mc146818.hh b/src/dev/mc146818.hh
index e145ad3fd..e33658903 100644
--- a/src/dev/mc146818.hh
+++ b/src/dev/mc146818.hh
@@ -64,6 +64,23 @@ class MC146818 : public EventManager
         virtual const char *description() const;
     };
 
+    /** Event for RTC periodic interrupt */
+    struct RTCTickEvent : public Event
+    {
+        MC146818 * parent;
+
+        RTCTickEvent(MC146818 * _parent) : parent(_parent)
+        {
+            parent->schedule(this, curTick + Clock::Int::s);
+        }
+
+        /** Event process to occur at interrupt*/
+        void process();
+
+        /** Event description */
+        const char *description() const;
+    };
+
   private:
     std::string _name;
     const std::string &name() const { return _name; }
@@ -71,6 +88,9 @@ class MC146818 : public EventManager
     /** RTC periodic interrupt event */
     RTCEvent event;
 
+    /** RTC tick event */
+    RTCTickEvent tickEvent;
+
     /** Data for real-time clock function */
     union {
         uint8_t clock_data[10];
@@ -89,6 +109,10 @@ class MC146818 : public EventManager
         };
     };
 
+    struct tm curTime;
+
+    void setTime(const struct tm time);
+
     /** RTC status register A */
     uint8_t stat_regA;
 
@@ -106,6 +130,8 @@ class MC146818 : public EventManager
     /** RTC read data */
     uint8_t readData(const uint8_t addr);
 
+    void tickClock();
+
     /**
       * Serialize this object to the given output stream.
       * @param base The base name of the counter object.
-- 
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