phy: core: Add devm_of_phy_get_by_index to phy-core

Some generic drivers, such as ehci, may use multiple phys and for such
drivers referencing phy(s) by name(s) does not make sense. Instead of
inventing new naming schemes and using custom code to iterate through them,
such drivers are better of using nameless phy bindings and using this newly
introduced API to iterate through them.

Signed-off-by: Arun Ramamurthy <arun.ramamurthy@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
[kishon@ti.com: fix compilation errors]
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
diff --git a/Documentation/phy.txt b/Documentation/phy.txt
index 371361c..b388c5a 100644
--- a/Documentation/phy.txt
+++ b/Documentation/phy.txt
@@ -76,6 +76,8 @@
 struct phy *phy_optional_get(struct device *dev, const char *string);
 struct phy *devm_phy_get(struct device *dev, const char *string);
 struct phy *devm_phy_optional_get(struct device *dev, const char *string);
+struct phy *devm_of_phy_get_by_index(struct device *dev, struct device_node *np,
+				     int index);
 
 phy_get, phy_optional_get, devm_phy_get and devm_phy_optional_get can
 be used to get the PHY. In the case of dt boot, the string arguments
@@ -86,7 +88,10 @@
 the the devres data and devres data is freed. phy_optional_get and
 devm_phy_optional_get should be used when the phy is optional. These
 two functions will never return -ENODEV, but instead returns NULL when
-the phy cannot be found.
+the phy cannot be found.Some generic drivers, such as ehci, may use multiple
+phys and for such drivers referencing phy(s) by name(s) does not make sense. In
+this case, devm_of_phy_get_by_index can be used to get a phy reference based on
+the index.
 
 It should be noted that NULL is a valid phy reference. All phy
 consumer calls on the NULL phy become NOPs. That is the release calls,