Add rollover protection to the STM32 RTC sampling logic
git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@3963 7fd9a85b-ad96-42d3-883c-3090e2eb8679
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patacongo
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@ -83,7 +83,6 @@
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#define RTC_TIMEMSB_REG STM32_BKP_DR1
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/************************************************************************************
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* Private Data
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************************************************************************************/
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@ -93,8 +92,8 @@
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* - on start-up
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* - during operation, reported by LSE interrupt
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*/
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volatile bool g_rtc_enabled = false;
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volatile bool g_rtc_enabled = false;
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/************************************************************************************
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* Private Functions
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@ -109,13 +108,11 @@ static inline void stm32_rtc_beginwr(void)
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modifyreg16(STM32_RTC_CRL, 0, RTC_CRL_CNF);
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}
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static inline void stm32_rtc_endwr(void)
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{
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modifyreg16(STM32_RTC_CRL, RTC_CRL_CNF, 0);
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}
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/** Wait for registerred to synchronise with RTC module, call after power-up only */
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static inline void stm32_rtc_wait4rsf(void)
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{
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@ -123,8 +120,6 @@ static inline void stm32_rtc_wait4rsf(void)
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while( !(getreg16(STM32_RTC_CRL) & RTC_CRL_RSF) ) up_waste();
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}
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/************************************************************************************
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* Interrupt Service Routines
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************************************************************************************/
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@ -147,7 +142,6 @@ static int stm32_rtc_overflow_isr(int irq, void *context)
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return 0;
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}
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/************************************************************************************
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* Public Function - Initialization
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************************************************************************************/
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@ -175,13 +169,13 @@ int up_rtcinitialize(void)
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// \todo Get state from this function, if everything is
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// okay and whether it is already enabled (if it was disabled
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// reset upper time register
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// reset upper time register)
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g_rtc_enabled = true;
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// \todo Possible stall? should we set the timeout period? and return with -1
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stm32_rtc_wait4rsf();
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/* Configure prescaler, note that this are write-only registers */
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/* Configure prescaler, note that these are write-only registers */
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stm32_rtc_beginwr();
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putreg16(prescaler >> 16, STM32_RTC_PRLH);
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@ -206,17 +200,53 @@ int up_rtcinitialize(void)
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return OK;
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}
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/** Get time (counter) value
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*
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* \return time, where the unit depends on the prescaler value
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**/
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clock_t up_rtc_getclock(void)
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{
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return ( (uint32_t)getreg16(STM32_RTC_CNTH) << 16) |
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(uint32_t)getreg16(STM32_RTC_CNTL);
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}
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irqstate_t flags;
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uint16_t cnth;
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uint16_t cntl;
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uint16_t tmp;
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/* The RTC counter is read from two 16-bit registers to form one 32-bit
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* value. Because these are non-atomic operations, many things can happen
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* between the two reads: This thread could get suspended or interrrupted
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* or the lower 16-bit counter could rollover between reads. Disabling
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* interrupts will prevent suspensions and interruptions:
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*/
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flags = irqsave();
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/* And the following loop will handle any clock rollover events that may
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* happen between samples. Most of the time (like 99.9%), the following
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* loop will execute only once. In the rare rollover case, it should
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* execute no more than 2 times.
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*/
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do
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{
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tmp = getreg16(STM32_RTC_CNTL);
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cnth = getreg16(STM32_RTC_CNTH);
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cntl = getreg16(STM32_RTC_CNTL);
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}
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/* The second sample of CNTL could be less than the first sample of CNTL
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* only if rollover occurred. In that case, CNTH may or may not be out
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* of sync. The best thing to do is try again until we know that no
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* rollover occurred.
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*/
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while (cntl < tmp);
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irqrestore(flags);
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/* Then return the full 32-bit counter value */
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return ((uint32_t)cnth << 16) | (uint32_t)cntl;
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}
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/** Set time (counter) value
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*
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@ -231,7 +261,6 @@ void up_rtc_setclock(clock_t newclock)
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stm32_rtc_endwr();
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}
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time_t up_rtc_gettime(void)
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{
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/* Fetch time from LSB (hardware counter) and MSB (backup domain)
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@ -263,7 +292,6 @@ time_t up_rtc_gettime(void)
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return time_msb | time_lsb;
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}
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void up_rtc_settime(time_t newtime)
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{
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/* Do reverse compared to gettime above */
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@ -281,7 +309,6 @@ void up_rtc_settime(time_t newtime)
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irqrestore( irqs );
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}
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/** Set ALARM at which time ALARM callback is going to be generated
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*
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* The function sets the alarm and return present time at the time
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@ -304,12 +331,10 @@ clock_t up_rtc_setalarm(clock_t atclock)
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return up_rtc_getclock();
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}
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/** Set alarm output pin */
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void stm32_rtc_settalarmpin(bool activate)
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{
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}
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#endif // defined(CONFIG_STM32_BKP)
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/** \} */
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