serial: Provide STM32Cube based serial driver on stm32f1, stm32f4

STM32Cube based implementation allows single driver file for
all stm32 based SoCs.
By maximizing code reuse, use of STM32Cube eases new SoCs
porting into Zephyr and provides better maintanability and
maturity.

Change-Id: Ief4b723add3dfc8b2a839683559c5a4c5d5eb837
Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

arch/arm/soc/st_stm32/stm32f1/soc.c

@@ -60,6 +60,9 @@ static int stm32f1_init(struct device *arg)
 
 	irq_unlock(key);
 
+	/* Update CMSIS SystemCoreClock variable (HCLK) */
+	SystemCoreClock = CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC;
+
 	return 0;
 }
 

arch/arm/soc/st_stm32/stm32f4/soc.c

@@ -61,6 +61,9 @@ static int st_stm32f4_init(struct device *arg)
 
 	irq_unlock(key);
 
+	/* Update CMSIS SystemCoreClock variable (HCLK) */
+	SystemCoreClock = CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC;
+
 	return 0;
 }