fix(core): fix power manager rtc event scheduling.

diff --git a/core/embed/sys/power_manager/stm32u5/power_manager.c b/core/embed/sys/power_manager/stm32u5/power_manager.c
index 39df59e0c..4e601867c 100644
--- a/core/embed/sys/power_manager/stm32u5/power_manager.c
+++ b/core/embed/sys/power_manager/stm32u5/power_manager.c
@@ -29,6 +29,7 @@
 
 #ifdef USE_RTC
 #include <sys/rtc.h>
+#include <sys/rtc_scheduler.h>
 #endif
 
 #include "../fuel_gauge/battery_model.h"
@@ -237,14 +238,12 @@ pm_status_t pm_get_state(pm_state_t* state) {
 
 // This callback is called from inside the system_suspend() function
 // when the rtc wake-up timer expires.
-// - The callback can schedule the next wake-up by calling
-// rtc_wakeup_timer_start().
-// - If the callback return with wakeup_flags set, system_suspend() returns.
 #ifdef USE_RTC
 void pm_rtc_wakeup_callback(void* context) {
-  // No need to do anything here, but left as a placeholder for potential
-  // future use. This is an optimal place where to set a wakeup flag from RTC
-  // wakeup_flags_set(WAKEUP_FLAG_RTC);
+  pm_driver_t* drv = &g_pm;
+
+  // Clear autohibernate event reference
+  drv->autohibernate_event_id = 0;
 }
 #endif
 
@@ -282,6 +281,14 @@ pm_status_t pm_suspend(wakeup_flags_t* wakeup_reason) {
 
   wakeup_flags_t wakeup_flags = system_suspend();
 
+#ifdef USE_RTC
+  // Cancel autohibernate event if scheduled
+  if (drv->autohibernate_event_id != 0) {
+    rtc_cancel_wakeup_event(drv->autohibernate_event_id);
+    drv->autohibernate_event_id = 0;
+  }
+#endif
+
   // Wait for pmic measurements to stabilize the fuel gauge estimation.
   pm_status_t status = pm_wait_to_stabilize(drv, PM_STABILIZATION_TIMEOUT_MS);
   if (status != PM_OK) {
@@ -559,9 +566,11 @@ bool pm_driver_suspend(void) {
     // Driver just woke up from suspend and have no data available yet.
     // Request the suspend but wait for the next pmic_meausrement
     drv->suspending = true;
-
   } else {
+#ifdef USE_RTC
+    // Schedule auto-hibernation rtc event
     pm_schedule_rtc_wakeup();
+#endif
     drv->suspended = true;
   }
 
@@ -573,6 +582,8 @@ bool pm_driver_suspend(void) {
   return true;
 }
 
+#ifdef USE_RTC
+
 bool pm_schedule_rtc_wakeup(void) {
   pm_driver_t* drv = &g_pm;
 
@@ -580,8 +591,6 @@ bool pm_schedule_rtc_wakeup(void) {
     return false;
   }
 
-#ifdef USE_RTC
-
   // Capture the timestamp when device was active for the last time.
   if (!rtc_get_timestamp(&drv->last_active_timestamp)) {
     return false;
@@ -594,20 +603,17 @@ bool pm_schedule_rtc_wakeup(void) {
     pm_hibernate();
   }
 
-  uint32_t time_to_hibernate =
-      PM_AUTO_HIBERNATE_TIMEOUT_S -
-      (drv->last_active_timestamp - drv->suspend_timestamp);
-
-  rtc_wakeup_timer_start(time_to_hibernate, pm_rtc_wakeup_callback, NULL);
-
-#endif
-
-  systimer_delete(drv->monitoring_timer);
+  if (drv->autohibernate_event_id == 0) {
+    rtc_schedule_wakeup_event(
+        drv->suspend_timestamp + PM_AUTO_HIBERNATE_TIMEOUT_S,
+        pm_rtc_wakeup_callback, NULL, &drv->autohibernate_event_id);
+  }
 
-  drv->suspended = true;
   return true;
 }
 
+#endif
+
 bool pm_is_charging(void) {
   pm_driver_t* drv = &g_pm;
 
@@ -661,7 +667,6 @@ bool pm_driver_resume(void) {
   drv->state_machine_stabilized = false;
 
 #ifdef USE_RTC
-  rtc_wakeup_timer_stop();
 
   uint32_t rtc_timestamp;
   rtc_get_timestamp(&rtc_timestamp);
diff --git a/core/embed/sys/power_manager/stm32u5/power_manager_internal.h b/core/embed/sys/power_manager/stm32u5/power_manager_internal.h
index 9cb6afd34..e079a7c34 100644
--- a/core/embed/sys/power_manager/stm32u5/power_manager_internal.h
+++ b/core/embed/sys/power_manager/stm32u5/power_manager_internal.h
@@ -19,10 +19,12 @@
 
 #pragma once
 
+#include <trezor_types.h>
+
 #include <sys/pmic.h>
 #include <sys/power_manager.h>
+#include <sys/rtc_scheduler.h>
 #include <sys/systimer.h>
-#include <trezor_types.h>
 
 #include "../fuel_gauge/fuel_gauge.h"
 #include "../stwlc38/stwlc38.h"
@@ -135,6 +137,7 @@ typedef struct {
   uint32_t suspend_timestamp;
   uint32_t last_active_timestamp;
   uint32_t time_in_suspend_s;
+  rtc_event_id_t autohibernate_event_id;
 
 } pm_driver_t;
 
diff --git a/core/embed/sys/power_manager/stm32u5/power_monitoring.c b/core/embed/sys/power_manager/stm32u5/power_monitoring.c
index 24ab5dee3..f708c80e6 100644
--- a/core/embed/sys/power_manager/stm32u5/power_monitoring.c
+++ b/core/embed/sys/power_manager/stm32u5/power_monitoring.c
@@ -90,6 +90,8 @@ void pm_pmic_data_ready(void* context, pmic_report_t* report) {
 
   } else {
     if (drv->woke_up_from_suspend) {
+#ifdef USE_RTC
+
       // Use known battery self-discharge rate to compensate the fuel gauge
       // estimation during the suspend period. Since this period may be very
       // long and the battery temperature may vary, use the average ambient
@@ -98,15 +100,17 @@ void pm_pmic_data_ready(void* context, pmic_report_t* report) {
                                PM_SELF_DISG_RATE_SUSPEND_MA, 25.0f);
 
       // TODO: Currently in suspend mode we use single self-discharge rate
-      // but in practive the discharge rate may change in case the BLE chip
+      // but in practive the discharge rate may change in case some components
       // remains active. Since the device is very likely to stay in suspend
       // mode for limited time, for now we decided to neglect this. but in
-      // the future we may want to distinguish between suspend mode
-      // with/without BLE and use different self-discharge rates.
+      // the future we may want to distinguish between different suspend modes
+      // and use different self-discharge rates.
 
       fuel_gauge_set_soc(&drv->fuel_gauge, drv->fuel_gauge.soc,
                          drv->fuel_gauge.P);
 
+#endif  // USE_RTC
+
       // clear the flag
       drv->woke_up_from_suspend = false;
 
@@ -142,7 +146,10 @@ void pm_pmic_data_ready(void* context, pmic_report_t* report) {
     pm_store_data_to_backup_ram();
 
     if (drv->suspending) {
+#ifdef USE_RTC
+      // Schedule auto-hibernation rtc event
       pm_schedule_rtc_wakeup();
+#endif
       drv->suspending = false;
       drv->suspended = true;
     }