stmmac: intel: Enable SERDES PHY rx clk for PSE

EHL PSE SGMII mode requires to ungate the SERDES PHY rx clk for power up
sequence and vice versa.
Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c

@@ -153,6 +153,11 @@ static int intel_serdes_powerup(struct net_device *ndev, void *priv_data)
 		return data;
 	}
 
+	/* PSE only - ungate SGMII PHY Rx Clock */
+	if (intel_priv->is_pse)
+		mdiobus_modify(priv->mii, serdes_phy_addr, SERDES_GCR0,
+			       0, SERDES_PHY_RX_CLK);
+
 	return 0;
 }
 
@@ -168,6 +173,11 @@ static void intel_serdes_powerdown(struct net_device *ndev, void *intel_data)
 
 	serdes_phy_addr = intel_priv->mdio_adhoc_addr;
 
+	/* PSE only - gate SGMII PHY Rx Clock */
+	if (intel_priv->is_pse)
+		mdiobus_modify(priv->mii, serdes_phy_addr, SERDES_GCR0,
+			       SERDES_PHY_RX_CLK, 0);
+
 	/*  move power state to P3 */
 	data = mdiobus_read(priv->mii, serdes_phy_addr, SERDES_GCR0);
 

drivers/net/ethernet/stmicro/stmmac/dwmac-intel.h

@@ -14,6 +14,7 @@
 
 /* SERDES defines */
 #define SERDES_PLL_CLK		BIT(0)		/* PLL clk valid signal */
+#define SERDES_PHY_RX_CLK	BIT(1)		/* PSE SGMII PHY rx clk */
 #define SERDES_RST		BIT(2)		/* Serdes Reset */
 #define SERDES_PWR_ST_MASK	GENMASK(6, 4)	/* Serdes Power state*/
 #define SERDES_PWR_ST_SHIFT	4