mimxrt/machine_rtc: Improve the RTC init at boot.

By clearing the tamper bits and enabling access to the registers for all
code, just in case that this was set.  It keeps the clock running on
battery and the calibration setting.

Signed-off-by: robert-hh <robert@hammelrath.com>

ports/mimxrt/Makefile

@@ -137,6 +137,7 @@ SRC_HAL_IMX_C += \
 	$(MCU_DIR)/drivers/fsl_pit.c \
 	$(MCU_DIR)/drivers/fsl_pwm.c \
 	$(MCU_DIR)/drivers/fsl_sai.c \
+	$(MCU_DIR)/drivers/fsl_snvs_hp.c \
 	$(MCU_DIR)/drivers/fsl_snvs_lp.c \
 	$(MCU_DIR)/drivers/fsl_wdog.c \
 	$(MCU_DIR)/system_$(MCU_SERIES)$(MCU_CORE).c \

ports/mimxrt/machine_rtc.c

@@ -30,6 +30,7 @@
 #include "modmachine.h"
 #include "ticks.h"
 #include "fsl_snvs_lp.h"
+#include "fsl_snvs_hp.h"
 
 typedef struct _machine_rtc_obj_t {
     mp_obj_base_t base;
@@ -41,6 +42,12 @@ STATIC const machine_rtc_obj_t machine_rtc_obj = {{&machine_rtc_type}};
 
 // Start the RTC Timer.
 void machine_rtc_start(void) {
+    // Enable Non-Privileged Software Access
+    SNVS->HPCOMR |= SNVS_HPCOMR_NPSWA_EN_MASK;
+    // Do a basic init.
+    SNVS_LP_Init(SNVS);
+    // Disable all external Tamper
+    SNVS_LP_DisableAllExternalTamper(SNVS);
 
     SNVS_LP_SRTC_StartTimer(SNVS);
     // If the date is not set, set it to a more recent start date,