adjust the tick in MIX mode depending on the rtc clock

In Mix mode, the SSR is counting on a fqce APRE which is
RTCCLK freq / 'PREDIV_A + 1).
This value is 256Hz when RTC is clocked by LSE.
This frqe gives a tick of 3.9ms (= 1/256 * 1000)

Signed-off-by: Francois Ramu <francois.ramu@st.com>

Author: FRASTM

src/BSP/timer_if.c

@@ -318,11 +318,12 @@ uint32_t TIMER_IF_Convert_ms2Tick(uint32_t timeMilliSec)
   /* USER CODE BEGIN TIMER_IF_Convert_ms2Tick */
 
   /* USER CODE END TIMER_IF_Convert_ms2Tick */
-  ret = ((uint32_t)((((uint64_t) timeMilliSec) << RTC_N_PREDIV_S) / 1000));
+  ret = ((uint64_t)timeMilliSec * MS_TO_TICK) / 1000;
+
   /* USER CODE BEGIN TIMER_IF_Convert_ms2Tick_Last */
 
   /* USER CODE END TIMER_IF_Convert_ms2Tick_Last */
-  return ret;
+  return (uint32_t)ret;
 }
 
 uint32_t TIMER_IF_Convert_Tick2ms(uint32_t tick)
@@ -331,7 +332,7 @@ uint32_t TIMER_IF_Convert_Tick2ms(uint32_t tick)
   /* USER CODE BEGIN TIMER_IF_Convert_Tick2ms */
 
   /* USER CODE END TIMER_IF_Convert_Tick2ms */
-  ret = ((uint32_t)((((uint64_t)(tick)) * 1000) >> RTC_N_PREDIV_S));
+  ret = tick * TICK_TO_MS;
   /* USER CODE BEGIN TIMER_IF_Convert_Tick2ms_Last */
 
   /* USER CODE END TIMER_IF_Convert_Tick2ms_Last */
@@ -384,12 +385,8 @@ uint32_t TIMER_IF_GetTime(uint32_t *mSeconds)
 
   ticks = (((uint64_t) timerValueMSB) << 32) + timerValueLsb;
 
-  seconds = (uint32_t)(ticks >> RTC_N_PREDIV_S);
-
-  ticks = (uint32_t) ticks & RTC_PREDIV_S;
-
-  *mSeconds = TIMER_IF_Convert_Tick2ms(ticks);
-
+  seconds = ticks / MS_TO_TICK;
+  *mSeconds = (ticks * 1000) / MS_TO_TICK;
   /* USER CODE BEGIN TIMER_IF_GetTime_Last */
 
   /* USER CODE END TIMER_IF_GetTime_Last */

src/BSP/timer_if.h

@@ -39,6 +39,17 @@ extern "C" {
 #define UTIL_TIMER_IRQ_MAP_INIT()
 #endif /* UTIL_TIMER_IRQ_MAP_INIT */
 
+/*
+ * With RTC (RtcHandle.Instance) clocked by LSE, the APRE freq is 256Hz (default)
+ * (1 tick is 3.9ms (when APREDIV = 0x7F)
+ * for other RTC clock freq, the formula is ck_apre = RTC_clock / (prediv_A +1)
+ */
+#define MS_TO_TICK \
+  (uint32_t)(LL_RCC_GetRTCClockFreq() / (LL_RTC_GetAsynchPrescaler(RtcHandle.Instance) + 1))
+
+/* Give one more (to adjust to x3.9 factor) */
+#define TICK_TO_MS ((1000/MS_TO_TICK) + 1)
+
 void UTIL_TIMER_IRQ_MAP_PROCESS(void *data);
 
 /* USER CODE END Includes */