net: phy: re-design phy_modes to be self-contained

of_get_phy_mode() uses a local array to map phy_interface_t values from
include/linux/net/phy.h to a string which is read from the 'phy-mode' or
'phy-connection-type' property. In preparation for exposing the PHY
interface mode through sysfs, perform the following:

- mode phy_modes from drivers/of/of_net.c to include/linux/phy.h such
  that it is right below the phy_interface_t enum
- make it a static inline function returning the string such that we can
  use it by just including include/linux/net/phy.h
- add a PHY_INTERFACE_MODE_MAX enum value to guard the iteration in
  of_get_phy_mode()

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/phy.h

@@ -74,8 +74,50 @@ typedef enum {
 	PHY_INTERFACE_MODE_RTBI,
 	PHY_INTERFACE_MODE_SMII,
 	PHY_INTERFACE_MODE_XGMII,
+	PHY_INTERFACE_MODE_MAX,
 } phy_interface_t;
 
+/**
+ * It maps 'enum phy_interface_t' found in include/linux/phy.h
+ * into the device tree binding of 'phy-mode', so that Ethernet
+ * device driver can get phy interface from device tree.
+ */
+static inline const char *phy_modes(phy_interface_t interface)
+{
+	switch (interface) {
+	case PHY_INTERFACE_MODE_NA:
+		return "";
+	case PHY_INTERFACE_MODE_MII:
+		return "mii";
+	case PHY_INTERFACE_MODE_GMII:
+		return "gmii";
+	case PHY_INTERFACE_MODE_SGMII:
+		return "sgmii";
+	case PHY_INTERFACE_MODE_TBI:
+		return "tbi";
+	case PHY_INTERFACE_MODE_REVMII:
+		return "rev-mii";
+	case PHY_INTERFACE_MODE_RMII:
+		return "rmii";
+	case PHY_INTERFACE_MODE_RGMII:
+		return "rgmii";
+	case PHY_INTERFACE_MODE_RGMII_ID:
+		return "rgmii-id";
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+		return "rgmii-rxid";
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+		return "rgmii-txid";
+	case PHY_INTERFACE_MODE_RTBI:
+		return "rtbi";
+	case PHY_INTERFACE_MODE_SMII:
+		return "smii";
+	case PHY_INTERFACE_MODE_XGMII:
+		return "xgmii";
+	default:
+		return "unknown";
+	}
+}
+
 
 #define PHY_INIT_TIMEOUT	100000
 #define PHY_STATE_TIME		1