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stm32l5: Put a timeout on waiting for LSE 

Do not run into an infinite loop if the LSE does not start up.

Signed-off-by: Michael Jung <mijung@gmx.net>
This commit is contained in:
Michael Jung 2021-03-15 21:19:45 +01:00 committed by Xiang Xiao
parent c031e4d2ee
commit 3581289661
1 changed files with 18 additions and 6 deletions
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24
arch/arm/src/stm32l5/stm32l5_lse.c
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@ -54,6 +54,8 @@
* Pre-processor Definitions
****************************************************************************/
#define LSERDY_TIMEOUT (500 * CONFIG_BOARD_LOOPSPERMSEC)
#ifdef CONFIG_STM32L5_RTC_LSECLOCK_START_DRV_CAPABILITY
# if CONFIG_STM32L5_RTC_LSECLOCK_START_DRV_CAPABILITY < 0 || \
CONFIG_STM32L5_RTC_LSECLOCK_START_DRV_CAPABILITY > 3
@ -84,6 +86,7 @@ void stm32l5_rcc_enablelse(void)
{
bool writable;
uint32_t regval;
volatile int32_t timeout;
/* Check if both the External Low-Speed (LSE) oscillator and the LSE system
* clock are already running.
@ -119,16 +122,25 @@ void stm32l5_rcc_enablelse(void)
putreg32(regval, STM32L5_RCC_BDCR);
/* Wait for the LSE clock to be ready */
/* Wait for the LSE clock to be ready (or until a timeout elapsed)
*/
while (((regval = getreg32(STM32L5_RCC_BDCR)) & RCC_BDCR_LSERDY) == 0)
for (timeout = LSERDY_TIMEOUT; timeout > 0; timeout--)
{
up_waste();
/* Check if the LSERDY flag is the set in the BDCR */
regval = getreg32(STM32L5_RCC_BDCR);
if (regval & RCC_BDCR_LSERDY)
{
/* If so, then break-out with timeout > 0 */
break;
}
}
/* Enable LSE system clock. The LSE system clock has been introduced
* first by the STM32L5 family of MCUs. It seems to provide a means
* to gate the LSE clock distribution to peripherals. It must be
/* Enable LSE system clock. The LSE system clock seems to provide a
* means to gate the LSE clock distribution to peripherals. It must be
* enabled for MSI PLL mode (syncing the MSI to the LSE).
*/