[nrf fromtree] pm: Extend pm notifier to be able to report substate

I am surprised this notifier didn't already report the substate id, it
seems important since different substate obviously are defined for a
reason, they can be having a different effect on the system.

Signed-off-by: Declan Snyder <[email protected]>
(cherry picked from commit ae1f131)

Author: Declan Snyder

include/zephyr/pm/pm.h

@@ -55,16 +55,33 @@ extern "C" {
  */
 struct pm_notifier {
 	sys_snode_t _node;
-	/**
-	 * Application defined function for doing any target specific operations
-	 * for power state entry.
-	 */
-	void (*state_entry)(enum pm_state state);
-	/**
-	 * Application defined function for doing any target specific operations
-	 * for power state exit.
-	 */
-	void (*state_exit)(enum pm_state state);
+	union {
+		struct {
+			/**
+			 * Application defined function for doing any target specific operations
+			 * for power state entry.
+			 */
+			void (*state_entry)(enum pm_state state);
+			/**
+			 * Application defined function for doing any target specific operations
+			 * for power state exit.
+			 */
+			void (*state_exit)(enum pm_state state);
+		};
+		struct {
+			/**
+			 * Application defined function for doing any target specific operations
+			 * for power state entry. Reports the substate id additionally.
+			 */
+			void (*substate_entry)(enum pm_state state, uint8_t substate_id);
+			/**
+			 * Application defined function for doing any target specific operations
+			 * for power state exit. Reports the substate id additionally.
+			 */
+			void (*substate_exit)(enum pm_state state, uint8_t substate_id);
+		};
+	};
+	bool report_substate; /* 0 is for backwards compatibility that didn't report substates */
 };
 
 #if defined(CONFIG_PM) || defined(__DOXYGEN__)

subsys/pm/pm.c

@@ -47,19 +47,29 @@ static inline void pm_state_notify(bool entering_state)
 {
 	struct pm_notifier *notifier;
 	k_spinlock_key_t pm_notifier_key;
-	void (*callback)(enum pm_state state);
+	union {
+		void (*without_substate)(enum pm_state state);
+		void (*with_substate)(enum pm_state state, uint8_t substate_id);
+	} callback;
 
 	pm_notifier_key = k_spin_lock(&pm_notifier_lock);
 	SYS_SLIST_FOR_EACH_CONTAINER(&pm_notifiers, notifier, _node) {
 		if (entering_state) {
-			callback = notifier->state_entry;
+			/* should be equivalent to also setting the "with substate" */
+			callback.without_substate = notifier->state_entry;
 		} else {
-			callback = notifier->state_exit;
+			/* should be equivalent to also setting the "with substate" */
+			callback.without_substate = notifier->state_exit;
 		}
 
-		if (callback) {
-			callback(z_cpus_pm_state[CPU_ID]->state);
-		}
+		if (callback.with_substate && notifier->report_substate) {
+			callback.with_substate(z_cpus_pm_state[CPU_ID]->state,
+					       z_cpus_pm_state[CPU_ID]->substate_id);
+		} else if (callback.without_substate) {
+			callback.without_substate(z_cpus_pm_state[CPU_ID]->state);
+		} else {
+			/* intentionally empty */
+		};
 	}
 	k_spin_unlock(&pm_notifier_lock, pm_notifier_key);
 }