net: phy: add minimal support for QSGMII PHY

This commit adds the necessary definitions for the PHY layer to
recognize "qsgmii" as a valid PHY interface. A QSMII interface, as
defined at
http://en.wikipedia.org/wiki/Media_Independent_Interface#Quad_Serial_Gigabit_Media_Independent_Interface,
is "is a method of combining four SGMII lines into a 5Gbit/s
interface. QSGMII, like SGMII, uses LVDS signalling for the TX and RX
data and a single LVDS clock signal. QSGMII uses significantly fewer
signal lines than four SGMII busses."

This type of MAC <-> PHY connection might require special handling on
the MAC driver side, so it should be possible to express this type of
MAC <-> PHY connection, for example in the Device Tree.

Change-Id: Ib4a62bf218548d84affe7787ce96468bf71b80af
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: b9d12085f2f531fdea67f0361564e0812696227c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
[athand@codeaurora.org: Trivial modification to compile in 3.10]
Signed-off-by: Arunkumar T <athand@codeaurora.org>
Signed-off-by: Kranthikumar Kurapati <kkurap@codeaurora.org>

Documentation/devicetree/bindings/net/ethernet.txt

@@ -0,0 +1,25 @@
+The following properties are common to the Ethernet controllers:
+
+- local-mac-address: array of 6 bytes, specifies the MAC address that was
+  assigned to the network device;
+- mac-address: array of 6 bytes, specifies the MAC address that was last used by
+  the boot program; should be used in cases where the MAC address assigned to
+  the device by the boot program is different from the "local-mac-address"
+  property;
+- max-speed: number, specifies maximum speed in Mbit/s supported by the device;
+- max-frame-size: number, maximum transfer unit (IEEE defined MTU), rather than
+  the maximum frame size (there's contradiction in ePAPR).
+- phy-mode: string, operation mode of the PHY interface; supported values are
+  "mii", "gmii", "sgmii", "qsgmii", "tbi", "rev-mii", "rmii", "rgmii", "rgmii-id",
+  "rgmii-rxid", "rgmii-txid", "rtbi", "smii", "xgmii"; this is now a de-facto
+  standard property;
+- phy-connection-type: the same as "phy-mode" property but described in ePAPR;
+- phy-handle: phandle, specifies a reference to a node representing a PHY
+  device; this property is described in ePAPR and so preferred;
+- phy: the same as "phy-handle" property, not recommended for new bindings.
+- phy-device: the same as "phy-handle" property, not recommended for new
+  bindings.
+
+Child nodes of the Ethernet controller are typically the individual PHY devices
+connected via the MDIO bus (sometimes the MDIO bus controller is separate).
+They are described in the phy.txt file in this same directory.

drivers/of/of_net.c

@@ -29,6 +29,7 @@ static const char *phy_modes[] = {
 	[PHY_INTERFACE_MODE_RGMII_TXID] = "rgmii-txid",
 	[PHY_INTERFACE_MODE_RTBI]	= "rtbi",
 	[PHY_INTERFACE_MODE_SMII]	= "smii",
+	[PHY_INTERFACE_MODE_QSGMII]	= "qsgmii",
 };
 
 /**

include/linux/phy.h

@@ -64,6 +64,7 @@ typedef enum {
 	PHY_INTERFACE_MODE_RGMII_TXID,
 	PHY_INTERFACE_MODE_RTBI,
 	PHY_INTERFACE_MODE_SMII,
+	PHY_INTERFACE_MODE_QSGMII,
 } phy_interface_t;