net: pcs: add 2500BASEX support for Intel mGbE controller

XPCS IP supports 2500BASEX as PHY interface. It is configured as
autonegotiation disable to cater for PHYs that does not supports 2500BASEX
autonegotiation.

v2: Add supported link speed masking.
v3: Restructure to introduce xpcs_config_2500basex() used to configure the
    xpcs for 2.5G speeds. Added 2500BASEX specific information for
    configuration.
v4: Fix indentation error

Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/pcs/pcs-xpcs.c

@@ -57,9 +57,12 @@
 
 /* Clause 37 Defines */
 /* VR MII MMD registers offsets */
+#define DW_VR_MII_MMD_CTRL		0x0000
 #define DW_VR_MII_DIG_CTRL1		0x8000
 #define DW_VR_MII_AN_CTRL		0x8001
 #define DW_VR_MII_AN_INTR_STS		0x8002
+/* Enable 2.5G Mode */
+#define DW_VR_MII_DIG_CTRL1_2G5_EN	BIT(2)
 /* EEE Mode Control Register */
 #define DW_VR_MII_EEE_MCTRL0		0x8006
 #define DW_VR_MII_EEE_MCTRL1		0x800b
@@ -86,6 +89,11 @@
 #define DW_VR_MII_C37_ANSGM_SP_1000		0x2
 #define DW_VR_MII_C37_ANSGM_SP_LNKSTS		BIT(4)
 
+/* SR MII MMD Control defines */
+#define AN_CL37_EN		BIT(12)	/* Enable Clause 37 auto-nego */
+#define SGMII_SPEED_SS13	BIT(13)	/* SGMII speed along with SS6 */
+#define SGMII_SPEED_SS6		BIT(6)	/* SGMII speed along with SS13 */
+
 /* VR MII EEE Control 0 defines */
 #define DW_VR_MII_EEE_LTX_EN		BIT(0)  /* LPI Tx Enable */
 #define DW_VR_MII_EEE_LRX_EN		BIT(1)  /* LPI Rx Enable */
@@ -161,6 +169,14 @@ static const int xpcs_sgmii_features[] = {
 	__ETHTOOL_LINK_MODE_MASK_NBITS,
 };
 
+static const int xpcs_2500basex_features[] = {
+	ETHTOOL_LINK_MODE_Asym_Pause_BIT,
+	ETHTOOL_LINK_MODE_Autoneg_BIT,
+	ETHTOOL_LINK_MODE_2500baseX_Full_BIT,
+	ETHTOOL_LINK_MODE_2500baseT_Full_BIT,
+	__ETHTOOL_LINK_MODE_MASK_NBITS,
+};
+
 static const phy_interface_t xpcs_usxgmii_interfaces[] = {
 	PHY_INTERFACE_MODE_USXGMII,
 };
@@ -177,11 +193,17 @@ static const phy_interface_t xpcs_sgmii_interfaces[] = {
 	PHY_INTERFACE_MODE_SGMII,
 };
 
+static const phy_interface_t xpcs_2500basex_interfaces[] = {
+	PHY_INTERFACE_MODE_2500BASEX,
+	PHY_INTERFACE_MODE_MAX,
+};
+
 enum {
 	DW_XPCS_USXGMII,
 	DW_XPCS_10GKR,
 	DW_XPCS_XLGMII,
 	DW_XPCS_SGMII,
+	DW_XPCS_2500BASEX,
 	DW_XPCS_INTERFACE_MAX,
 };
 
@@ -306,6 +328,7 @@ static int xpcs_soft_reset(struct mdio_xpcs_args *xpcs,
 		dev = MDIO_MMD_PCS;
 		break;
 	case DW_AN_C37_SGMII:
+	case DW_2500BASEX:
 		dev = MDIO_MMD_VEND2;
 		break;
 	default:
@@ -804,6 +827,28 @@ static int xpcs_config_aneg_c37_sgmii(struct mdio_xpcs_args *xpcs)
 	return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
 }
 
+static int xpcs_config_2500basex(struct mdio_xpcs_args *xpcs)
+{
+	int ret;
+
+	ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1);
+	if (ret < 0)
+		return ret;
+	ret |= DW_VR_MII_DIG_CTRL1_2G5_EN;
+	ret &= ~DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
+	ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
+	if (ret < 0)
+		return ret;
+
+	ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL);
+	if (ret < 0)
+		return ret;
+	ret &= ~AN_CL37_EN;
+	ret |= SGMII_SPEED_SS6;
+	ret &= ~SGMII_SPEED_SS13;
+	return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL, ret);
+}
+
 static int xpcs_do_config(struct mdio_xpcs_args *xpcs,
 			  phy_interface_t interface, unsigned int mode)
 {
@@ -827,6 +872,11 @@ static int xpcs_do_config(struct mdio_xpcs_args *xpcs,
 		if (ret)
 			return ret;
 		break;
+	case DW_2500BASEX:
+		ret = xpcs_config_2500basex(xpcs);
+		if (ret)
+			return ret;
+		break;
 	default:
 		return -1;
 	}
@@ -1023,6 +1073,12 @@ static const struct xpcs_compat synopsys_xpcs_compat[DW_XPCS_INTERFACE_MAX] = {
 		.num_interfaces = ARRAY_SIZE(xpcs_sgmii_interfaces),
 		.an_mode = DW_AN_C37_SGMII,
 	},
+	[DW_XPCS_2500BASEX] = {
+		.supported = xpcs_2500basex_features,
+		.interface = xpcs_2500basex_interfaces,
+		.num_interfaces = ARRAY_SIZE(xpcs_2500basex_features),
+		.an_mode = DW_2500BASEX,
+	},
 };
 
 static const struct xpcs_id xpcs_id_list[] = {

include/linux/pcs/pcs-xpcs.h

@@ -13,6 +13,7 @@
 /* AN mode */
 #define DW_AN_C73			1
 #define DW_AN_C37_SGMII			2
+#define DW_2500BASEX			3
 
 struct xpcs_id;