net: phy: read MMD ID from all present MMDs

Expand the device_ids[] array to allow all MMD IDs to be read rather
than just the first 8 MMDs, but only read the ID if the MDIO_STAT2
register reports that a device really is present here for these new
devices to maintain compatibility with our current behaviour.  Note
that only a limited number of devices have MDIO_STAT2.

88X3310 PHY vendor MMDs do are marked as present in the
devices_in_package, but do not contain IEE 802.3 compatible register
sets in their lower space.  This avoids reading incorrect values as MMD
identifiers.
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -774,6 +774,19 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr,
 		if (!(devs_in_pkg & (1 << i)))
 			continue;
 
+		if (i == MDIO_MMD_VEND1 || i == MDIO_MMD_VEND2) {
+			/* Probe the "Device Present" bits for the vendor MMDs
+			 * to ignore these if they do not contain IEEE 802.3
+			 * registers.
+			 */
+			ret = phy_c45_probe_present(bus, addr, i);
+			if (ret < 0)
+				return ret;
+
+			if (!ret)
+				continue;
+		}
+
 		phy_reg = mdiobus_c45_read(bus, addr, i, MII_PHYSID1);
 		if (phy_reg < 0)
 			return -EIO;

include/linux/phy.h

@@ -399,7 +399,7 @@ enum phy_state {
 struct phy_c45_device_ids {
 	u32 devices_in_package;
 	u32 mmds_present;
-	u32 device_ids[8];
+	u32 device_ids[MDIO_MMD_NUM];
 };
 
 struct macsec_context;