From 7e1edd8d16ef8552da032804e91a7730caa2c0de Mon Sep 17 00:00:00 2001
From: barthess <barthess@35acf78f-673a-0410-8e92-d51de3d6d3f4>
Date: Sat, 8 Dec 2012 18:24:20 +0000
Subject: STM32. RTCv1. Fixed wasting of BKP registers in RTCv1 driver (bug
 3594005)

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@4890 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/hal/platforms/STM32/RTCv1/rtc_lld.c | 40 +++++++++++++++-------------------
 os/hal/platforms/STM32/RTCv1/rtc_lld.h |  1 +
 os/hal/platforms/STM32F1xx/hal_lld.c   |  3 +++
 3 files changed, 22 insertions(+), 22 deletions(-)

(limited to 'os/hal')

diff --git a/os/hal/platforms/STM32/RTCv1/rtc_lld.c b/os/hal/platforms/STM32/RTCv1/rtc_lld.c
index 0fb538c2d..72b91a28c 100644
--- a/os/hal/platforms/STM32/RTCv1/rtc_lld.c
+++ b/os/hal/platforms/STM32/RTCv1/rtc_lld.c
@@ -126,10 +126,24 @@ CH_IRQ_HANDLER(RTC_IRQHandler) {
 /*===========================================================================*/
 
 /**
- * @brief   Enable access to registers and initialize RTC if BKP domain
- *          was previously reseted.
- * @note:   Cold start time of LSE oscillator on STM32 platform 
- *          takes about 3 seconds.
+ * @brief   Load value of RTCCLK to prescaler registers.
+ * @note    The pre-scaler must not be set on every reset as RTC clock
+ *          counts are lost when it is set.
+ * @note    This function designed to be called from
+ *          hal_lld_backup_domain_init(). Because there is only place
+ *          where possible to detect BKP domain reset event reliably.
+ *
+ * @notapi
+ */
+void rtc_lld_set_prescaler(void){
+  rtc_lld_acquire();
+  RTC->PRLH = (uint16_t)((STM32_RTCCLK - 1) >> 16) & 0x000F;
+  RTC->PRLL = (uint16_t)(((STM32_RTCCLK - 1))      & 0xFFFF);
+  rtc_lld_release();
+}
+
+/**
+ * @brief   Initialize RTC.
  *
  * @notapi
  */
@@ -142,24 +156,6 @@ void rtc_lld_init(void){
   /* Required because access to PRL.*/
   rtc_lld_apb1_sync();
 
-  /*
-   * Writes preload register only if its value is not equal to desired value.
-   *
-   * Ref CD00171190: RM0008 Reference manual Cls 18.4.3 The RTC->PRL registers
-   * are write only. We must store the value for the pre-scaler in BKP->DR1
-   * and BKP->DR1 so we know it has been set.
-   * The pre-scaler must not be set on every reset as RTC clock counts are
-   * lost when it is set.
-   */
-  if ((STM32_RTCCLK - 1) != ((((uint32_t)BKP->DR1) << 16) | BKP->DR2)){
-    rtc_lld_acquire();
-    RTC->PRLH = (uint16_t)((STM32_RTCCLK - 1) >> 16) & 0x000F;
-    BKP->DR1  = (uint16_t)((STM32_RTCCLK - 1) >> 16) & 0x000F;
-    RTC->PRLL = (uint16_t)(((STM32_RTCCLK - 1)) & 0xFFFF);
-    BKP->DR2  = (uint16_t)(((STM32_RTCCLK - 1)) & 0xFFFF);
-    rtc_lld_release();
-  }
-
   /* All interrupts initially disabled.*/
   rtc_lld_wait_write();
   RTC->CRH = 0;
diff --git a/os/hal/platforms/STM32/RTCv1/rtc_lld.h b/os/hal/platforms/STM32/RTCv1/rtc_lld.h
index c0ad92525..050f66d5e 100644
--- a/os/hal/platforms/STM32/RTCv1/rtc_lld.h
+++ b/os/hal/platforms/STM32/RTCv1/rtc_lld.h
@@ -168,6 +168,7 @@ extern RTCDriver RTCD1;
 #ifdef __cplusplus
 extern "C" {
 #endif
+  void rtc_lld_set_prescaler(void);
   void rtc_lld_init(void);
   void rtc_lld_set_time(RTCDriver *rtcp, const RTCTime *timespec);
   void rtc_lld_get_time(RTCDriver *rtcp, RTCTime *timespec);
diff --git a/os/hal/platforms/STM32F1xx/hal_lld.c b/os/hal/platforms/STM32F1xx/hal_lld.c
index 9fda0b3e7..bcb7d3f47 100644
--- a/os/hal/platforms/STM32F1xx/hal_lld.c
+++ b/os/hal/platforms/STM32F1xx/hal_lld.c
@@ -74,6 +74,9 @@ static void hal_lld_backup_domain_init(void) {
 
     /* RTC clock enabled.*/
     RCC->BDCR |= RCC_BDCR_RTCEN;
+
+    /* Prescaler value loaded in registers.*/
+    rtc_lld_set_prescaler();
   }
 #endif /* STM32_RTCSEL != STM32_RTCSEL_NOCLOCK */
 }
-- 
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