pm: Use fixed cpu id in single core case

When there are no multiple cores than fixing id to 0 saves few
cycles.

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

subsys/pm/pm.c

@@ -62,7 +62,7 @@ static inline void pm_state_notify(bool entering_state)
 		}
 
 		if (callback) {
-			callback(z_cpus_pm_state[_current_cpu->id].state);
+			callback(z_cpus_pm_state[CPU_ID].state);
 		}
 	}
 	k_spin_unlock(&pm_notifier_lock, pm_notifier_key);
@@ -93,7 +93,7 @@ static inline int32_t ticks_expiring_sooner(int32_t ticks1, int32_t ticks2)
 
 void pm_system_resume(void)
 {
-	uint8_t id = _current_cpu->id;
+	uint8_t id = CPU_ID;
 
 	/*
 	 * This notification is called from the ISR of the event
@@ -142,7 +142,7 @@ bool pm_state_force(uint8_t cpu, const struct pm_state_info *info)
 
 bool pm_system_suspend(int32_t kernel_ticks)
 {
-	uint8_t id = _current_cpu->id;
+	uint8_t id = CPU_ID;
 	k_spinlock_key_t key;
 	int32_t ticks, events_ticks;
 

subsys/pm/pm_stats.c

@@ -53,17 +53,17 @@ SYS_INIT(pm_stats_init, PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
 
 void pm_stats_start(void)
 {
-	time_start[_current_cpu->id] = k_cycle_get_32();
+	time_start[CPU_ID] = k_cycle_get_32();
 }
 
 void pm_stats_stop(void)
 {
-	time_stop[_current_cpu->id] = k_cycle_get_32();
+	time_stop[CPU_ID] = k_cycle_get_32();
 }
 
 void pm_stats_update(enum pm_state state)
 {
-	uint8_t cpu = _current_cpu->id;
+	uint8_t cpu = CPU_ID;
 	uint32_t time_total = time_stop[cpu] - time_start[cpu];
 
 	STATS_INC(stats[cpu][state], state_count);