MT-150266: net: fec: add direct MDIO bus access via SIOCGMIIREG/SIOCSMIIREG

drivers/net/ethernet/freescale/fec_main.c

@@ -4024,6 +4024,62 @@ static int fec_hwtstamp_set(struct net_device *ndev,
 	return fec_ptp_set(ndev, config, extack);
 }
 
+/* Provide direct MDIO bus register access via SIOCGMIIREG/SIOCSMIIREG.
+ *
+ * The generic phy_do_ioctl_running() path only works when a phydev is
+ * attached to this net_device and routes register access through the PHY
+ * state machine (with side effects such as autoneg restarts). On boards
+ * where the FEC is wired to a DSA switch (e.g. SJA1105) over a fixed-link,
+ * there is no attached phydev, so the generic path returns -ENODEV and the
+ * MDIO bus is unreachable from userspace.
+ *
+ * Intercept the two MII register commands and service them directly against
+ * fep->mii_bus so bring-up/diagnostic tooling can reach any device address
+ * on the bus without side effects. A Clause-45-encoded phy_id (MII_ADDR_C45)
+ * is split into prtad/devad and routed through the C45 bus accessors, mirroring
+ * phy_mii_ioctl() so C45 PHYs on the FEC bus remain reachable. All other
+ * commands fall through to the standard handler. (Reworked from a patch shipped
+ * with the Audinate EVK.)
+ */
+static int fec_enet_ioctl(struct net_device *ndev, struct ifreq *rq, int cmd)
+{
+	struct fec_enet_private *fep = netdev_priv(ndev);
+	struct mii_ioctl_data *mii = if_mii(rq);
+	int prtad, devad, ret;
+	bool is_c45;
+
+	switch (cmd) {
+	case SIOCGMIIREG:
+		is_c45 = mdio_phy_id_is_c45(mii->phy_id);
+		if (is_c45) {
+			prtad = mdio_phy_id_prtad(mii->phy_id);
+			devad = mdio_phy_id_devad(mii->phy_id);
+			ret = mdiobus_c45_read_nested(fep->mii_bus, prtad, devad,
+						      mii->reg_num);
+		} else {
+			ret = mdiobus_read_nested(fep->mii_bus, mii->phy_id,
+						  mii->reg_num);
+		}
+		if (ret < 0)
+			return ret;
+		mii->val_out = ret;
+		return 0;
+	case SIOCSMIIREG:
+		is_c45 = mdio_phy_id_is_c45(mii->phy_id);
+		if (is_c45) {
+			prtad = mdio_phy_id_prtad(mii->phy_id);
+			devad = mdio_phy_id_devad(mii->phy_id);
+			return mdiobus_c45_write_nested(fep->mii_bus, prtad,
+							devad, mii->reg_num,
+							mii->val_in);
+		}
+		return mdiobus_write_nested(fep->mii_bus, mii->phy_id,
+					    mii->reg_num, mii->val_in);
+	default:
+		return phy_do_ioctl_running(ndev, rq, cmd);
+	}
+}
+
 static const struct net_device_ops fec_netdev_ops = {
 	.ndo_open		= fec_enet_open,
 	.ndo_stop		= fec_enet_close,
@@ -4033,7 +4089,7 @@ static const struct net_device_ops fec_netdev_ops = {
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_tx_timeout		= fec_timeout,
 	.ndo_set_mac_address	= fec_set_mac_address,
-	.ndo_eth_ioctl		= phy_do_ioctl_running,
+	.ndo_eth_ioctl		= fec_enet_ioctl,
 	.ndo_set_features	= fec_set_features,
 	.ndo_bpf		= fec_enet_bpf,
 	.ndo_xdp_xmit		= fec_enet_xdp_xmit,