[PATCH net-next v3 2/2] net: pcs: configure xpcs 2.5G speed mode

[Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>]

From: Voon Weifeng <weifeng.voon@intel.com>

Besides setting 2.5G configuration, this patch will also disable
automatic speed mode change. This is due to the 2.5G mode is
using the same functionality as 1G mode except the clock rate is
2.5 times the original rate. Hence, auto-negotiation is disabled
to make sure it will only be in 2.5G mode.

Signed-off-by: Voon Weifeng <weifeng.voon@intel.com>
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
---
 drivers/net/pcs/pcs-xpcs.c   | 23 +++++++++++++++++++++++
 drivers/net/phy/phylink.c    |  2 ++
 include/linux/pcs/pcs-xpcs.h |  1 +
 3 files changed, 26 insertions(+)

diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 944ba105cac1..e52bcb9a9199 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -60,10 +60,14 @@
 
 /* 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)
+
 /* VR_MII_DIG_CTRL1 */
 #define DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW		BIT(9)
 
@@ -86,6 +90,11 @@
 #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 */
+
 static const int xpcs_usxgmii_features[] = {
 	ETHTOOL_LINK_MODE_Pause_BIT,
 	ETHTOOL_LINK_MODE_Asym_Pause_BIT,
@@ -141,6 +150,7 @@ static const int xpcs_sgmii_features[] = {
 	ETHTOOL_LINK_MODE_100baseT_Full_BIT,
 	ETHTOOL_LINK_MODE_1000baseT_Half_BIT,
 	ETHTOOL_LINK_MODE_1000baseT_Full_BIT,
+	ETHTOOL_LINK_MODE_2500baseT_Full_BIT,
 	__ETHTOOL_LINK_MODE_MASK_NBITS,
 };
 
@@ -654,6 +664,19 @@ static int xpcs_config_aneg_c37_sgmii(struct mdio_xpcs_args *xpcs)
 {
 	int ret;
 
+	if (xpcs->speed_2500_en) {
+		ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1);
+		ret |= DW_VR_MII_DIG_CTRL1_2G5_EN;
+		ret &= ~DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
+		xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
+
+		ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL);
+		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);
+	}
+
 	/* For AN for C37 SGMII mode, the settings are :-
 	 * 1) VR_MII_AN_CTRL Bit(2:1)[PCS_MODE] = 10b (SGMII AN)
 	 * 2) VR_MII_AN_CTRL Bit(3) [TX_CONFIG] = 0b (MAC side SGMII)
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 12a047d47dec..c95dfe4e5310 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -290,6 +290,8 @@ static int phylink_parse_mode(struct phylink *pl, struct fwnode_handle *fwnode)
 
 		switch (pl->link_config.interface) {
 		case PHY_INTERFACE_MODE_SGMII:
+			phylink_set(pl->supported, 2500baseT_Full);
+			fallthrough;
 		case PHY_INTERFACE_MODE_QSGMII:
 			phylink_set(pl->supported, 10baseT_Half);
 			phylink_set(pl->supported, 10baseT_Full);
diff --git a/include/linux/pcs/pcs-xpcs.h b/include/linux/pcs/pcs-xpcs.h
index 2cb5188a7ef1..6b94b2a48e0c 100644
--- a/include/linux/pcs/pcs-xpcs.h
+++ b/include/linux/pcs/pcs-xpcs.h
@@ -19,6 +19,7 @@ struct mdio_xpcs_args {
 	struct mii_bus *bus;
 	int addr;
 	int an_mode;
+	bool speed_2500_en;
 };
 
 struct mdio_xpcs_ops {
-- 
2.17.1