kernel: mt7530: add support for in-band managed link

Add support for in-band managed link status to support SFP cage
connected to port 5 of the MT7531 switch on the Bananapi BPi-R3.

Signed-off-by: Daniel Golle <[email protected]>

target/linux/generic/pending-5.15/731-net-dsa-mt7530-add-support-for-in-band-link-status.patch

@@ -0,0 +1,123 @@
+From 8e18c5fef75debfae3531fbd6901f3bf317d91ed Mon Sep 17 00:00:00 2001
+From: Daniel Golle <[email protected]>
+Date: Fri, 9 Sep 2022 04:28:43 +0100
+Subject: [PATCH] net: dsa: mt7530: add support for in-band link status
+To: [email protected],
+    [email protected]
+Cc: Russell King <[email protected]>,
+    Sean Wang <[email protected]>,
+    Landen Chao <[email protected]>,
+    DENG Qingfang <[email protected]>,
+    Andrew Lunn <[email protected]>,
+    Vivien Didelot <[email protected]>,
+    Florian Fainelli <[email protected]>,
+    Vladimir Oltean <[email protected]>,
+    David S. Miller <[email protected]>,
+    Eric Dumazet <[email protected]>,
+    Jakub Kicinski <[email protected]>,
+    Paolo Abeni <[email protected]>,
+    Matthias Brugger <[email protected]>,
+    Philipp Zabel <[email protected]>
+
+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.
+
+Signed-off-by: Daniel Golle <[email protected]>
+---
+ drivers/net/dsa/mt7530.c | 48 +++++++++++++++++++++++++++++-----------
+ 1 file changed, 35 insertions(+), 13 deletions(-)
+
+--- a/drivers/net/dsa/mt7530.c
++++ b/drivers/net/dsa/mt7530.c
+@@ -2703,9 +2703,6 @@ mt7531_mac_config(struct dsa_switch *ds,
+ 	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;
+@@ -2781,13 +2778,6 @@ unsupported:
+ 		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;
+@@ -2924,6 +2914,9 @@ static void mt753x_phylink_get_caps(stru
+ 	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.
+@@ -3019,16 +3012,43 @@ mt7531_sgmii_pcs_get_state_an(struct mt7
+ 	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;
++
++	if (state->interface == PHY_INTERFACE_MODE_2500BASEX)
++		state->speed = SPEED_2500;
++	else
++		state->speed = SPEED_1000;
++
++	state->duplex = DUPLEX_FULL;
++	state->pause = 0;
++}
++
+ 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;
++	unsigned int val;
+ 
+-	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,
+@@ -3069,6 +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);