net: dsa: mt7530: add support for in-band link status

Read link status from SGMII PCS for in-band managed 2500Base-X and
1000Base-X connection on a MAC port of the MT7531. This is needed to
get the SFP cage working which is connected to SGMII interface of
port 5 of the MT7531 switch IC on the Bananapi BPi-R3 board.
While at it also handle an_complete for both the autoneg and the
non-autoneg codepath.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mt7530.c

@@ -2699,9 +2699,6 @@ mt7531_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
 	case PHY_INTERFACE_MODE_NA:
 	case PHY_INTERFACE_MODE_1000BASEX:
 	case PHY_INTERFACE_MODE_2500BASEX:
-		if (phylink_autoneg_inband(mode))
-			return -EINVAL;
-
 		return mt7531_sgmii_setup_mode_force(priv, port, interface);
 	default:
 		return -EINVAL;
@@ -2777,13 +2774,6 @@ mt753x_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
 		return;
 	}
 
-	if (phylink_autoneg_inband(mode) &&
-	    state->interface != PHY_INTERFACE_MODE_SGMII) {
-		dev_err(ds->dev, "%s: in-band negotiation unsupported\n",
-			__func__);
-		return;
-	}
-
 	mcr_cur = mt7530_read(priv, MT7530_PMCR_P(port));
 	mcr_new = mcr_cur;
 	mcr_new &= ~PMCR_LINK_SETTINGS_MASK;
@@ -2922,6 +2912,9 @@ static void mt753x_phylink_get_caps(struct dsa_switch *ds, int port,
 	config->mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE |
 				   MAC_10 | MAC_100 | MAC_1000FD;
 
+	if ((priv->id == ID_MT7531) && mt753x_is_mac_port(port))
+		config->mac_capabilities |= MAC_2500FD;
+
 	/* This driver does not make use of the speed, duplex, pause or the
 	 * advertisement in its mac_config, so it is safe to mark this driver
 	 * as non-legacy.
@@ -2987,6 +2980,7 @@ mt7531_sgmii_pcs_get_state_an(struct mt7530_priv *priv, int port,
 
 	status = mt7530_read(priv, MT7531_PCS_CONTROL_1(port));
 	state->link = !!(status & MT7531_SGMII_LINK_STATUS);
+	state->an_complete = !!(status & MT7531_SGMII_AN_COMPLETE);
 	if (state->interface == PHY_INTERFACE_MODE_SGMII &&
 	    (status & MT7531_SGMII_AN_ENABLE)) {
 		val = mt7530_read(priv, MT7531_PCS_SPEED_ABILITY(port));
@@ -3017,16 +3011,44 @@ mt7531_sgmii_pcs_get_state_an(struct mt7530_priv *priv, int port,
 	return 0;
 }
 
+static void
+mt7531_sgmii_pcs_get_state_inband(struct mt7530_priv *priv, int port,
+				  struct phylink_link_state *state)
+{
+	unsigned int val;
+
+	val = mt7530_read(priv, MT7531_PCS_CONTROL_1(port));
+	state->link = !!(val & MT7531_SGMII_LINK_STATUS);
+	if (!state->link)
+		return;
+
+	state->an_complete = state->link;
+
+	if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
+		state->speed = SPEED_2500;
+	else
+		state->speed = SPEED_1000;
+
+	state->duplex = DUPLEX_FULL;
+	state->pause = MLO_PAUSE_NONE;
+}
+
 static void mt7531_pcs_get_state(struct phylink_pcs *pcs,
 				 struct phylink_link_state *state)
 {
 	struct mt7530_priv *priv = pcs_to_mt753x_pcs(pcs)->priv;
 	int port = pcs_to_mt753x_pcs(pcs)->port;
 
-	if (state->interface == PHY_INTERFACE_MODE_SGMII)
+	if (state->interface == PHY_INTERFACE_MODE_SGMII) {
 		mt7531_sgmii_pcs_get_state_an(priv, port, state);
-	else
-		state->link = false;
+		return;
+	} else if ((state->interface == PHY_INTERFACE_MODE_1000BASEX) ||
+		   (state->interface == PHY_INTERFACE_MODE_2500BASEX)) {
+		mt7531_sgmii_pcs_get_state_inband(priv, port, state);
+		return;
+	}
+
+	state->link = false;
 }
 
 static int mt753x_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
@@ -3067,6 +3089,8 @@ mt753x_setup(struct dsa_switch *ds)
 		priv->pcs[i].pcs.ops = priv->info->pcs_ops;
 		priv->pcs[i].priv = priv;
 		priv->pcs[i].port = i;
+		if (mt753x_is_mac_port(i))
+			priv->pcs[i].pcs.poll = 1;
 	}
 
 	ret = priv->info->sw_setup(ds);

drivers/net/dsa/mt7530.h

@@ -373,6 +373,7 @@ enum mt7530_vlan_port_acc_frm {
 #define  MT7531_SGMII_LINK_STATUS	BIT(18)
 #define  MT7531_SGMII_AN_ENABLE		BIT(12)
 #define  MT7531_SGMII_AN_RESTART	BIT(9)
+#define  MT7531_SGMII_AN_COMPLETE	BIT(21)
 
 /* Register for SGMII PCS_SPPED_ABILITY */
 #define MT7531_PCS_SPEED_ABILITY(p)	MT7531_SGMII_REG(p, 0x08)