[RFC][PATCH 2/3][Resend] PM / runtime: Routine for checking device status during system suspend

["Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>]

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Add a new helper routine, pm_runtime_enabled_and_suspended(), to
allow subsystems (or PM domains) to check the runtime PM status of
devices during system suspend (possibly to avoid resuming those
devices upfront at that time).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/base/power/runtime.c |   28 ++++++++++++++++++++++++++++
 include/linux/pm_runtime.h   |    2 ++
 2 files changed, 30 insertions(+)

Index: linux-pm/include/linux/pm_runtime.h
===================================================================
--- linux-pm.orig/include/linux/pm_runtime.h
+++ linux-pm/include/linux/pm_runtime.h
@@ -57,6 +57,7 @@ extern unsigned long pm_runtime_autosusp
 extern void pm_runtime_update_max_time_suspended(struct device *dev,
 						 s64 delta_ns);
 extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable);
+extern bool pm_runtime_enabled_and_suspended(struct device *dev);
 
 static inline bool pm_children_suspended(struct device *dev)
 {
@@ -165,6 +166,7 @@ static inline unsigned long pm_runtime_a
 				struct device *dev) { return 0; }
 static inline void pm_runtime_set_memalloc_noio(struct device *dev,
 						bool enable){}
+static inline bool pm_runtime_enabled_and_suspended(struct device *dev) { return false; }
 
 #endif /* !CONFIG_PM_RUNTIME */
 
Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -1195,6 +1195,34 @@ void pm_runtime_enable(struct device *de
 EXPORT_SYMBOL_GPL(pm_runtime_enable);
 
 /**
+ * pm_runtime_enabled_and_suspended - Check runtime PM status of a device.
+ * @dev: Device to handle.
+ *
+ * This routine is to be executed during system suspend only, after
+ * device_prepare() has been executed for @dev.
+ *
+ * Return false if runtime PM is disabled for the device.  Otherwise, wait
+ * for pending transitions to complete and check the runtime PM status of the
+ * device after that.  Return true if it is RPM_SUSPENDED.
+ */
+bool pm_runtime_enabled_and_suspended(struct device *dev)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(&dev->power.lock, flags);
+	if (dev->power.disable_depth) {
+		ret = false;
+	} else {
+		__pm_runtime_barrier(dev);
+		ret = pm_runtime_status_suspended(dev);
+	}
+	spin_unlock_irqrestore(&dev->power.lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pm_runtime_enabled_and_suspended);
+
+/**
  * pm_runtime_forbid - Block runtime PM of a device.
  * @dev: Device to handle.
  *
--
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