ethtool, mdio, mii: Specify MDIO information fields in struct ethtool_cmd

Add comments for ethtool_cmd::phy_address and
ethtool_cmd::mdio_support, and definitions of the flags currently
used in mdio_support.

In the mdio library, assert that its own flags continue to match those
in the ethtool interface.

In the mii library, use the ethtool flag definition and stop
including <linux/mdio.h>.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index da5b2de..e1d9e0e 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -30,10 +30,15 @@
 				 * access it */
 	__u8	duplex;		/* Duplex, half or full */
 	__u8	port;		/* Which connector port */
-	__u8	phy_address;
+	__u8	phy_address;	/* MDIO PHY address (PRTAD for clause 45).
+				 * May be read-only or read-write
+				 * depending on the driver.
+				 */
 	__u8	transceiver;	/* Which transceiver to use */
 	__u8	autoneg;	/* Enable or disable autonegotiation */
-	__u8	mdio_support;
+	__u8	mdio_support;	/* MDIO protocols supported.  Read-only.
+				 * Not set by all drivers.
+				 */
 	__u32	maxtxpkt;	/* Tx pkts before generating tx int */
 	__u32	maxrxpkt;	/* Rx pkts before generating rx int */
 	__u16	speed_hi;       /* The forced speed (upper
@@ -59,6 +64,20 @@
 	return (ep->speed_hi << 16) | ep->speed;
 }
 
+/* Device supports clause 22 register access to PHY or peripherals
+ * using the interface defined in <linux/mii.h>.  This should not be
+ * set if there are known to be no such peripherals present or if
+ * the driver only emulates clause 22 registers for compatibility.
+ */
+#define ETH_MDIO_SUPPORTS_C22	1
+
+/* Device supports clause 45 register access to PHY or peripherals
+ * using the interface defined in <linux/mii.h> and <linux/mdio.h>.
+ * This should not be set if there are known to be no such peripherals
+ * present.
+ */
+#define ETH_MDIO_SUPPORTS_C45	2
+
 #define ETHTOOL_FWVERS_LEN	32
 #define ETHTOOL_BUSINFO_LEN	32
 /* these strings are set to whatever the driver author decides... */