phy: core: Allow phy_pm_runtime_xxx API calls with NULL phy

phy_init() and phy_exit() calls, and phy_power_on() and
phy_power_off() already accept NULL as valid PHY reference
and act as NOP. Extend same concept to phy runtime_pm APIs
to keep drivers (e.g. dwc3) code simple while dealing with
optional PHYs.
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/phy-core.c

@@ -153,6 +153,9 @@ int phy_pm_runtime_get(struct phy *phy)
 {
 	int ret;
 
+	if (!phy)
+		return 0;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return -ENOTSUPP;
 
@@ -168,6 +171,9 @@ int phy_pm_runtime_get_sync(struct phy *phy)
 {
 	int ret;
 
+	if (!phy)
+		return 0;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return -ENOTSUPP;
 
@@ -181,6 +187,9 @@ EXPORT_SYMBOL_GPL(phy_pm_runtime_get_sync);
 
 int phy_pm_runtime_put(struct phy *phy)
 {
+	if (!phy)
+		return 0;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return -ENOTSUPP;
 
@@ -190,6 +199,9 @@ EXPORT_SYMBOL_GPL(phy_pm_runtime_put);
 
 int phy_pm_runtime_put_sync(struct phy *phy)
 {
+	if (!phy)
+		return 0;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return -ENOTSUPP;
 
@@ -199,6 +211,9 @@ EXPORT_SYMBOL_GPL(phy_pm_runtime_put_sync);
 
 void phy_pm_runtime_allow(struct phy *phy)
 {
+	if (!phy)
+		return;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return;
 
@@ -208,6 +223,9 @@ EXPORT_SYMBOL_GPL(phy_pm_runtime_allow);
 
 void phy_pm_runtime_forbid(struct phy *phy)
 {
+	if (!phy)
+		return;
+
 	if (!pm_runtime_enabled(&phy->dev))
 		return;