net: stmmac: Add dedicated XPCS cleanup method

Currently the XPCS handler destruction is performed in the
stmmac_mdio_unregister() method. It doesn't look good because the handler
isn't originally created in the corresponding protagonist
stmmac_mdio_unregister(), but in the stmmac_xpcs_setup() function. In
order to have more coherent MDIO and XPCS setup/cleanup procedures,
let's move the DW XPCS destruction to the dedicated stmmac_pcs_clean()
method.

This method will also be used to cleanup PCS hardware using the
pcs_exit() callback that will be introduced to stmmac in a subsequent
patch.
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Co-developed-by: Romain Gantois <romain.gantois@bootlin.com>
Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Hariprasad Kelam <hkelam@marvell.com>
Link: https://lore.kernel.org/r/20240513-rzn1-gmac1-v7-2-6acf58b5440d@bootlin.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -361,6 +361,7 @@ int stmmac_mdio_unregister(struct net_device *ndev);
 int stmmac_mdio_register(struct net_device *ndev);
 int stmmac_mdio_reset(struct mii_bus *mii);
 int stmmac_xpcs_setup(struct mii_bus *mii);
+void stmmac_pcs_clean(struct net_device *ndev);
 void stmmac_set_ethtool_ops(struct net_device *netdev);
 
 int stmmac_init_tstamp_counter(struct stmmac_priv *priv, u32 systime_flags);

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -7789,8 +7789,9 @@ int stmmac_dvr_probe(struct device *device,
 
 error_netdev_register:
 	phylink_destroy(priv->phylink);
-error_xpcs_setup:
 error_phy_setup:
+	stmmac_pcs_clean(ndev);
+error_xpcs_setup:
 	if (priv->hw->pcs != STMMAC_PCS_TBI &&
 	    priv->hw->pcs != STMMAC_PCS_RTBI)
 		stmmac_mdio_unregister(ndev);
@@ -7832,6 +7833,9 @@ void stmmac_dvr_remove(struct device *dev)
 	if (priv->plat->stmmac_rst)
 		reset_control_assert(priv->plat->stmmac_rst);
 	reset_control_assert(priv->plat->stmmac_ahb_rst);
+
+	stmmac_pcs_clean(ndev);
+
 	if (priv->hw->pcs != STMMAC_PCS_TBI &&
 	    priv->hw->pcs != STMMAC_PCS_RTBI)
 		stmmac_mdio_unregister(ndev);

drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c

@@ -523,6 +523,17 @@ int stmmac_xpcs_setup(struct mii_bus *bus)
 	return 0;
 }
 
+void stmmac_pcs_clean(struct net_device *ndev)
+{
+	struct stmmac_priv *priv = netdev_priv(ndev);
+
+	if (!priv->hw->xpcs)
+		return;
+
+	xpcs_destroy(priv->hw->xpcs);
+	priv->hw->xpcs = NULL;
+}
+
 /**
  * stmmac_mdio_register
  * @ndev: net device structure
@@ -679,9 +690,6 @@ int stmmac_mdio_unregister(struct net_device *ndev)
 	if (!priv->mii)
 		return 0;
 
-	if (priv->hw->xpcs)
-		xpcs_destroy(priv->hw->xpcs);
-
 	mdiobus_unregister(priv->mii);
 	priv->mii->priv = NULL;
 	mdiobus_free(priv->mii);