net: add comments to phy APIs

Added a comment on the limitations of phy_find_by_mask API when scanning
MDIO buses with multiple PHYs present.  Added short descriptions to the
other APIs in phy.h for consistency.

Signed-off-by: Alex Marginean <alexm.osslist@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/phy.h

@@ -246,15 +246,71 @@ static inline int is_10g_interface(phy_interface_t interface)
 
 #endif
 
+/**
+ * phy_init() - Initializes the PHY drivers
+ *
+ * This function registers all available PHY drivers
+ *
+ * @return 0 if OK, -ve on error
+ */
 int phy_init(void);
+
+/**
+ * phy_reset() - Resets the specified PHY
+ *
+ * Issues a reset of the PHY and waits for it to complete
+ *
+ * @phydev:	PHY to reset
+ * @return 0 if OK, -ve on error
+ */
 int phy_reset(struct phy_device *phydev);
+
+/**
+ * phy_find_by_mask() - Searches for a PHY on the specified MDIO bus
+ *
+ * The function checks the PHY addresses flagged in phy_mask and returns a
+ * phy_device pointer if it detects a PHY.
+ * This function should only be called if just one PHY is expected to be present
+ * in the set of addresses flagged in phy_mask.  If multiple PHYs are present,
+ * it is undefined which of these PHYs is returned.
+ *
+ * @bus:	MII/MDIO bus to scan
+ * @phy_mask:	bitmap of PYH addresses to scan
+ * @interface:	type of MAC-PHY interface
+ * @return pointer to phy_device if a PHY is found, or NULL otherwise
+ */
 struct phy_device *phy_find_by_mask(struct mii_dev *bus, unsigned phy_mask,
 		phy_interface_t interface);
+
 #ifdef CONFIG_DM_ETH
+
+/**
+ * phy_connect_dev() - Associates the given pair of PHY and Ethernet devices
+ * @phydev:	PHY device
+ * @dev:	Ethernet device
+ */
 void phy_connect_dev(struct phy_device *phydev, struct udevice *dev);
+
+/**
+ * phy_connect() - Creates a PHY device for the Ethernet interface
+ *
+ * Creates a PHY device for the PHY at the given address, if one doesn't exist
+ * already, and associates it with the Ethernet device.
+ * The function may be called with addr <= 0, in this case addr value is ignored
+ * and the bus is scanned to detect a PHY.  Scanning should only be used if only
+ * one PHY is expected to be present on the MDIO bus, otherwise it is undefined
+ * which PHY is returned.
+ *
+ * @bus:	MII/MDIO bus that hosts the PHY
+ * @addr:	PHY address on MDIO bus
+ * @dev:	Ethernet device to associate to the PHY
+ * @interface:	type of MAC-PHY interface
+ * @return pointer to phy_device if a PHY is found, or NULL otherwise
+ */
 struct phy_device *phy_connect(struct mii_dev *bus, int addr,
 				struct udevice *dev,
 				phy_interface_t interface);
+
 static inline ofnode phy_get_ofnode(struct phy_device *phydev)
 {
 	if (ofnode_valid(phydev->node))
@@ -263,10 +319,34 @@ static inline ofnode phy_get_ofnode(struct phy_device *phydev)
 		return dev_ofnode(phydev->dev);
 }
 #else
+
+/**
+ * phy_connect_dev() - Associates the given pair of PHY and Ethernet devices
+ * @phydev:	PHY device
+ * @dev:	Ethernet device
+ */
 void phy_connect_dev(struct phy_device *phydev, struct eth_device *dev);
+
+/**
+ * phy_connect() - Creates a PHY device for the Ethernet interface
+ *
+ * Creates a PHY device for the PHY at the given address, if one doesn't exist
+ * already, and associates it with the Ethernet device.
+ * The function may be called with addr <= 0, in this case addr value is ignored
+ * and the bus is scanned to detect a PHY.  Scanning should only be used if only
+ * one PHY is expected to be present on the MDIO bus, otherwise it is undefined
+ * which PHY is returned.
+ *
+ * @bus:	MII/MDIO bus that hosts the PHY
+ * @addr:	PHY address on MDIO bus
+ * @dev:	Ethernet device to associate to the PHY
+ * @interface:	type of MAC-PHY interface
+ * @return pointer to phy_device if a PHY is found, or NULL otherwise
+ */
 struct phy_device *phy_connect(struct mii_dev *bus, int addr,
 				struct eth_device *dev,
 				phy_interface_t interface);
+
 static inline ofnode phy_get_ofnode(struct phy_device *phydev)
 {
 	return ofnode_null();