PM / wakeup: Add dev_wakeup_path() helper

[<patrice.chotard@st.com>]

From: Patrice Chotard <patrice.chotard@st.com>

Add dev_wakeup_path() helper to avoid to spread
dev->power.wakeup_path test in drivers.

In case CONFIG_PM_SLEEP is not set, wakeup_path is not defined,
dev_wakeup_path() is returning false.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
---

Currently, in mainline kernel, no drivers are testing dev->power.wakeup_path
for PM purpose. A stm32 serial driver patch will be submitted soon and will 
make usage of this helper.

 include/linux/pm_wakeup.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h
index aa3da6611533..d0bd13c19253 100644
--- a/include/linux/pm_wakeup.h
+++ b/include/linux/pm_wakeup.h
@@ -84,6 +84,11 @@ static inline bool device_may_wakeup(struct device *dev)
 	return dev->power.can_wakeup && !!dev->power.wakeup;
 }
 
+static inline bool device_wakeup_path(struct device *dev)
+{
+	return !!dev->power.wakeup_path;
+}
+
 static inline void device_set_wakeup_path(struct device *dev)
 {
 	dev->power.wakeup_path = true;
@@ -174,6 +179,11 @@ static inline bool device_may_wakeup(struct device *dev)
 	return dev->power.can_wakeup && dev->power.should_wakeup;
 }
 
+static inline bool device_wakeup_path(struct device *dev)
+{
+	return false;
+}
+
 static inline void device_set_wakeup_path(struct device *dev) {}
 
 static inline void __pm_stay_awake(struct wakeup_source *ws) {}
-- 
2.17.1