Merged in ziggurat29/boards/stm32l4_lse (pull request #35)

minor; changes to clocking config to specify the activation of LSE

configs/stm32l476vg-disco/include/stm32l476vg-disco-clocking.h

@@ -134,6 +134,10 @@
 #define STM32L4_USE_CLK48
 #define STM32L4_CLK48_SEL         RCC_CCIPR_CLK48SEL_PLLSAI1
 
+/* enable the LSE oscillator, used automatically trim the MSI, and for RTC */
+
+#define STM32L4_USE_LSE
+
 /* AHB clock (HCLK) is SYSCLK (80MHz) */
 
 #define STM32L4_RCC_CFGR_HPRE     RCC_CFGR_HPRE_SYSCLK      /* HCLK  = SYSCLK / 1 */

configs/stm32l476vg-disco/src/stm32_clockconfig.c

@@ -210,14 +210,14 @@ void stm32l4_board_clockconfig(void)
    stm32l4_rcc_enablelsi();
 #endif
 
-#if defined(CONFIG_RTC_LSECLOCK)
+#if defined(STM32L4_USE_LSE)
 
   /* Low speed external clock source LSE
    *
    * TODO: There is another case where the LSE needs to
    * be enabled: if the MCO1 pin selects LSE as source.
    */
-
+  stm32l4_pwr_enableclk(true);
   stm32l4_rcc_enablelse();
 #endif