igb: Fix for DH89xxCC near end loopback test

On this chipset it is required to configure the MPHY block for loopback tests. If MPHY is not configured then all loopback tests will report failures.

Signed-off-by: Robert Healy <robert.healy@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/igb/igb_ethtool.c b/drivers/net/igb/igb_ethtool.c
index ed63ff4..ff244ce 100644
--- a/drivers/net/igb/igb_ethtool.c
+++ b/drivers/net/igb/igb_ethtool.c
@@ -1461,6 +1461,22 @@
 
 	/* use CTRL_EXT to identify link type as SGMII can appear as copper */
 	if (reg & E1000_CTRL_EXT_LINK_MODE_MASK) {
+		if ((hw->device_id == E1000_DEV_ID_DH89XXCC_SGMII) ||
+		(hw->device_id == E1000_DEV_ID_DH89XXCC_SERDES) ||
+		(hw->device_id == E1000_DEV_ID_DH89XXCC_BACKPLANE) ||
+		(hw->device_id == E1000_DEV_ID_DH89XXCC_SFP)) {
+
+			/* Enable DH89xxCC MPHY for near end loopback */
+			reg = rd32(E1000_MPHY_ADDR_CTL);
+			reg = (reg & E1000_MPHY_ADDR_CTL_OFFSET_MASK) |
+			E1000_MPHY_PCS_CLK_REG_OFFSET;
+			wr32(E1000_MPHY_ADDR_CTL, reg);
+
+			reg = rd32(E1000_MPHY_DATA);
+			reg |= E1000_MPHY_PCS_CLK_REG_DIGINELBEN;
+			wr32(E1000_MPHY_DATA, reg);
+		}
+
 		reg = rd32(E1000_RCTL);
 		reg |= E1000_RCTL_LBM_TCVR;
 		wr32(E1000_RCTL, reg);
@@ -1502,6 +1518,23 @@
 	u32 rctl;
 	u16 phy_reg;
 
+	if ((hw->device_id == E1000_DEV_ID_DH89XXCC_SGMII) ||
+	(hw->device_id == E1000_DEV_ID_DH89XXCC_SERDES) ||
+	(hw->device_id == E1000_DEV_ID_DH89XXCC_BACKPLANE) ||
+	(hw->device_id == E1000_DEV_ID_DH89XXCC_SFP)) {
+		u32 reg;
+
+		/* Disable near end loopback on DH89xxCC */
+		reg = rd32(E1000_MPHY_ADDR_CTL);
+		reg = (reg & E1000_MPHY_ADDR_CTL_OFFSET_MASK) |
+		E1000_MPHY_PCS_CLK_REG_OFFSET;
+		wr32(E1000_MPHY_ADDR_CTL, reg);
+
+		reg = rd32(E1000_MPHY_DATA);
+		reg &= ~E1000_MPHY_PCS_CLK_REG_DIGINELBEN;
+		wr32(E1000_MPHY_DATA, reg);
+	}
+
 	rctl = rd32(E1000_RCTL);
 	rctl &= ~(E1000_RCTL_LBM_TCVR | E1000_RCTL_LBM_MAC);
 	wr32(E1000_RCTL, rctl);