rtc: improve WA for RTC incorrect read
- Improved WA for RTC read failure
- According to FE-3124064:
- Description:
The device supports CPU write and read access to the RTC Time register.
However, due to this erratum, Read from RTC TIME register may fail.
Workaround:
RTC TIME register should be read 100 times, return a the value which appears
most frequently as a proper value.
Change-Id: I05b20d633220bb8043f176fbb7d3c68c671b368a
Signed-off-by: Shaker Daibes <shaker@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/24986
Tested-by: Star_Automation <star@marvell.com>
Reviewed-by: Ofer Heifetz <oferh@marvell.com>
diff --git a/board/mv_ebu/common/USP/mv_rtc2.c b/board/mv_ebu/common/USP/mv_rtc2.c
index 53a321e..c61b405 100644
--- a/board/mv_ebu/common/USP/mv_rtc2.c
+++ b/board/mv_ebu/common/USP/mv_rtc2.c
@@ -70,9 +70,11 @@
#include "mv_rtc2.h"
#if defined(CONFIG_CMD_DATE)
-
+/* This define for WA in rtc read */
+#define SAMPLE_NR 100
static int rtc_ready = -1;
+
/*******************************************************/
void rtc_init(void)
{
@@ -97,38 +99,71 @@
rtc_ready = 1;
}
+#ifdef ERRATA_FE_3124064
+struct _strTime2Freq {
+ unsigned long nTime;
+ unsigned int nFreq;
+
+};
+#endif
+
/*******************************************************/
int rtc_get(struct rtc_time *tm)
{
- unsigned long time, time_check;
+#ifdef ERRATA_FE_3124064
+ /* Functional Errata Ref #: FE-3124064 - WA for failing time read attempts.
+ * Description:
+ * The device supports CPU write and read access to the RTC Time register.
+ * However, due to this erratum, Write to RTC TIME register may fail.
+ * Read from RTC TIME register may fail.
+ * Workaround:
+ * Before writing to RTC TIME register, issue a dummy write of 0x0 twice to
+ * RTC Status register.
+ * Configure maximum value (0x3FF) in write clock period in RTC Mbus Bridge
+ * Timing Control register.
+ * Before writing to RTC TIME register, issue a dummy write of 0x0 twice to
+ * RTC Status register.
+ * RTC TIME register should be read 100 times, then find the result
+ * that appear most frequently, use this result as the correct value.
+ */
+ unsigned long nTimeArray[SAMPLE_NR], i, j, nTime, nMax = 0, indexMax = SAMPLE_NR - 1;
+ struct _strTime2Freq sTimeToFreq[SAMPLE_NR];
+#endif
if (rtc_ready != 1)
rtc_init();
-
- time = RTC_READ_REG(RTC_TIME_REG_OFFS);
#ifdef ERRATA_FE_3124064
- /* Functional Errata Ref #: FE-3124064 - WA for failing time read attempts.
- * Description:
- * The device supports CPU write and read access to the RTC Time register.
- * However, due to this erratum, Write to RTC TIME register may fail.
- * Read from RTC TIME register may fail.
- * Workaround:
- * Before writing to RTC TIME register, issue a dummy write of 0x0 twice to RTC Status register.
- * RTC TIME register should be read twice, the second read will return a proper value.
- * Configure maximum value (0x3FF) in write clock period in RTC Mbus Bridge Timing Control register.
- * Functional Impact After Workaround is applied:
- * No functional impact after WA is applied
- */
- time_check = RTC_READ_REG(RTC_TIME_REG_OFFS);
- if ((time_check - time) > 1)
- time_check = RTC_READ_REG(RTC_TIME_REG_OFFS);
+ /* read RTC TIME register 100 times and save the values in array,
+ initialize the counters to zero */
+ for (i = 0; i < SAMPLE_NR; i++) {
+ sTimeToFreq[i].nFreq = 0;
+ nTimeArray[i] = RTC_READ_REG(RTC_TIME_REG_OFFS);
+ }
+ for (i = 0; i < SAMPLE_NR; i++) {
+ nTime = nTimeArray[i];
+ /* if nTime appears in sTimeToFreq array so add the counter of nTime value,
+ if didn't appear yet in counters array then allocate new member of
+ sTimeToFreq array with counter = 1 */
+ for (j = 0; j < SAMPLE_NR; j++) {
+ if (sTimeToFreq[j].nFreq == 0 || sTimeToFreq[j].nTime == nTime)
+ break;
+ }
+ if (sTimeToFreq[j].nFreq == 0)
+ sTimeToFreq[j].nTime = nTime;
+ sTimeToFreq[j].nFreq++;
+ /*find the most common result*/
+ if (nMax < sTimeToFreq[j].nFreq) {
+ indexMax = j;
+ nMax = sTimeToFreq[j].nFreq;
+ }
+ }
+
+ to_tm(sTimeToFreq[indexMax].nTime, tm);
+#else
+ to_tm(RTC_READ_REG(RTC_TIME_REG_OFFS), tm);
#endif
-
- to_tm(time_check, tm);
-
return 0;
}
-
/*******************************************************/
int rtc_set(struct rtc_time *tm)
{
