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>

drivers/net/igb/e1000_defines.h

@@ -512,6 +512,16 @@
 #define E1000_GCR_CMPL_TMOUT_RESEND     0x00010000
 #define E1000_GCR_CAP_VER2              0x00040000
 
+/* mPHY Address Control and Data Registers */
+#define E1000_MPHY_ADDR_CTL          0x0024 /* mPHY Address Control Register */
+#define E1000_MPHY_ADDR_CTL_OFFSET_MASK 0xFFFF0000
+#define E1000_MPHY_DATA                 0x0E10 /* mPHY Data Register */
+
+/* mPHY PCS CLK Register */
+#define E1000_MPHY_PCS_CLK_REG_OFFSET  0x0004 /* mPHY PCS CLK AFE CSR Offset */
+/* mPHY Near End Digital Loopback Override Bit */
+#define E1000_MPHY_PCS_CLK_REG_DIGINELBEN 0x10
+
 /* PHY Control Register */
 #define MII_CR_FULL_DUPLEX      0x0100  /* FDX =1, half duplex =0 */
 #define MII_CR_RESTART_AUTO_NEG 0x0200  /* Restart auto negotiation */

drivers/net/igb/igb_ethtool.c

@@ -1461,6 +1461,22 @@ static int igb_setup_loopback_test(struct igb_adapter *adapter)
 
 	/* 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 @@ static void igb_loopback_cleanup(struct igb_adapter *adapter)
 	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);