pm: Disable device pm per power state

Make it possible to disble device power management individually per
power state.  This allows targets tuning which states should
(and which should not) trigger device power management.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

dts/bindings/power/zephyr,power-state.yaml

@@ -31,3 +31,9 @@ properties:
     type: int
     description: |
         Worst case latency in microseconds required to exit the idle state.
+  zephyr,pm-device-disabled:
+    type: boolean
+    description: |
+       Disable system managed device power management for this state. When set,
+       the power management subsystem will not suspend devices before entering
+       this state.

include/zephyr/pm/state.h

@@ -134,12 +134,22 @@ struct pm_state_info {
 	 *			substate-id = <2>;
 	 *			min-residency-us = <20000>;
 	 *			exit-latency-us = <200>;
+	 *			zephyr,pm-device-disabled;
 	 *		};
 	 *	};
 	 * @endcode
 	 */
 	uint8_t substate_id;
 
+	/**
+	 * Whether or not this state triggers device power management.
+	 *
+	 * When this property is false the power management subsystem
+	 * will suspend devices before entering this state and will
+	 * properly resume them when leaving it.
+	 */
+	bool pm_device_disabled;
+
 	/**
 	 * Minimum residency duration in microseconds. It is the minimum
 	 * time for a given idle state to be worthwhile energywise.
@@ -209,6 +219,7 @@ struct pm_state_info {
 		.substate_id = DT_PROP_OR(node_id, substate_id, 0),	       \
 		.min_residency_us = DT_PROP_OR(node_id, min_residency_us, 0),  \
 		.exit_latency_us = DT_PROP_OR(node_id, exit_latency_us, 0),    \
+		.pm_device_disabled = DT_PROP(node_id, zephyr_pm_device_disabled),    \
 	}
 
 /**
@@ -260,6 +271,7 @@ struct pm_state_info {
  *				power-state-name = "suspend-to-ram";
  *				min-residency-us = <50000>;
  *				exit-latency-us = <500>;
+ *				zephyr,pm-device-disabled;
  *			};
  *		};
  *	};

subsys/pm/pm.c

@@ -205,7 +205,8 @@ bool pm_system_suspend(int32_t ticks)
 
 #if defined(CONFIG_PM_DEVICE) && !defined(CONFIG_PM_DEVICE_RUNTIME_EXCLUSIVE)
 	if (atomic_sub(&_cpus_active, 1) == 1) {
-		if (z_cpus_pm_state[id].state != PM_STATE_RUNTIME_IDLE) {
+		if ((z_cpus_pm_state[id].state != PM_STATE_RUNTIME_IDLE) &&
+		    !z_cpus_pm_state[id].pm_device_disabled) {
 			if (pm_suspend_devices()) {
 				pm_resume_devices();
 				z_cpus_pm_state[id].state = PM_STATE_ACTIVE;

tests/subsys/pm/device_wakeup_api/src/main.c

@@ -61,7 +61,7 @@ void pm_state_exit_post_ops(enum pm_state state, uint8_t substate_id)
 const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
 {
 	static const struct pm_state_info state = {
-		.state = PM_STATE_SUSPEND_TO_RAM
+		.state = PM_STATE_SUSPEND_TO_RAM,
 	};
 
 	ARG_UNUSED(cpu);

tests/subsys/pm/power_states_api/src/main.c

@@ -11,8 +11,8 @@
 /* Last state has not declared a minimum residency, so it should be
  * set the default 0 value
  */
-static struct pm_state_info infos[] = {{PM_STATE_SUSPEND_TO_IDLE, 0, 10000, 100},
+static struct pm_state_info infos[] = {{PM_STATE_SUSPEND_TO_IDLE, 0, false, 10000, 100},
-	       {PM_STATE_SUSPEND_TO_RAM, 0, 50000, 500}, {PM_STATE_STANDBY, 0, 0}};
+	{PM_STATE_SUSPEND_TO_RAM, 0, false, 50000, 500}, {PM_STATE_STANDBY, 0, false, 0}};
 static enum pm_state states[] = {PM_STATE_SUSPEND_TO_IDLE,
 			PM_STATE_SUSPEND_TO_RAM, PM_STATE_STANDBY};
 static enum pm_state wrong_states[] = {PM_STATE_SUSPEND_TO_DISK,