power: Add sys_pm_force_power_state() API

At the moment application which chosen policy based power
management does not have an option to override decision
taken by the policy (it could only disable some power
states).

This commit adds the sys_pm_force_power_state() method,
which allow the application to choose power state used
when OS decide to suspend the SoC.

Signed-off-by: Piotr Zięcik <[email protected]>

Author: pizi-nordic

include/power.h

@@ -28,6 +28,7 @@ extern unsigned char sys_pm_idle_exit_notify;
  * @brief Power Management states.
  */
 enum power_states {
+	SYS_POWER_STATE_AUTO	= (-2),
 	SYS_POWER_STATE_ACTIVE	= (-1),
 #ifdef CONFIG_SYS_POWER_LOW_POWER_STATE
 # ifdef CONFIG_SYS_POWER_STATE_CPU_LPS_SUPPORTED
@@ -200,6 +201,22 @@ void sys_resume(void);
  */
 extern enum power_states sys_suspend(s32_t ticks);
 
+/**
+ * @brief Force usage of given power state.
+ *
+ * This function overrides decision made by PM policy
+ * forcing usage of given power state in all subseqent
+ * suspend operations.
+ *
+ * Forcing the SYS_POWER_STATE_AUTO power state restores
+ * normal operation.
+ *
+ * @param state Power state which should be used in all
+ *		subsequent suspend operations or
+ *		SYS_POWER_STATE_AUTO.
+ */
+extern void sys_pm_force_power_state(enum power_states state);
+
 #ifdef CONFIG_PM_CONTROL_OS_DEBUG
 /**
  * @brief Dump Low Power states related debug info

subsys/power/power.c

@@ -16,6 +16,7 @@
 LOG_MODULE_REGISTER(power);
 
 static int post_ops_done = 1;
+static enum power_states forced_pm_state = SYS_POWER_STATE_AUTO;
 static enum power_states pm_state;
 
 #ifdef CONFIG_PM_CONTROL_OS_DEBUG
@@ -73,11 +74,22 @@ __weak void sys_pm_notify_lps_exit(enum power_states state)
 	/* This function can be overridden by the application. */
 }
 
+void sys_pm_force_power_state(enum power_states state)
+{
+	__ASSERT(state >= SYS_POWER_STATE_AUTO &&
+		 state <  SYS_POWER_STATE_MAX,
+		 "Invalid power state %d!", state);
+
+	forced_pm_state = state;
+}
+
 enum power_states sys_suspend(s32_t ticks)
 {
 	bool deep_sleep;
 
-	pm_state = sys_pm_policy_next_state(ticks);
+	pm_state = (forced_pm_state == SYS_POWER_STATE_AUTO) ?
+		   sys_pm_policy_next_state(ticks) : forced_pm_state;
+
 	if (pm_state == SYS_POWER_STATE_ACTIVE) {
 		LOG_DBG("No PM operations done.");
 		return pm_state;