The SJA1105 'PMA' code is actually PCS code to adapt to a custom PMA as
present in NXP SJA1105, that wants opposite differential lane polarity
in the TX direction, to account for an internal quirk.

We should write to the DW_VR_MII_DIG_CTRL2 PCS register from PCS code,
especially since the XPCS is about to gain more freeform support to
alter the lane polarity in the RX and TX directions.

The compat->pma_config() interface is kept for SJA1110, but is now
wrapped around a xpcs_pma_config() that handles SJA1105 as a quirk
implemented in common code.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 drivers/net/pcs/pcs-xpcs-nxp.c | 11 ----------
 drivers/net/pcs/pcs-xpcs.c     | 37 ++++++++++++++++++++++++++--------
 drivers/net/pcs/pcs-xpcs.h     |  2 +-
 3 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/drivers/net/pcs/pcs-xpcs-nxp.c b/drivers/net/pcs/pcs-xpcs-nxp.c
index e8efe94cf4ec..37708b28a7aa 100644
--- a/drivers/net/pcs/pcs-xpcs-nxp.c
+++ b/drivers/net/pcs/pcs-xpcs-nxp.c
@@ -64,17 +64,6 @@
 /* RX_CDR_CTLE register */
 #define SJA1110_RX_CDR_CTLE		0x8042
 
-/* In NXP SJA1105, the PCS is integrated with a PMA that has the TX lane
- * polarity inverted by default (PLUS is MINUS, MINUS is PLUS). To obtain
- * normal non-inverted behavior, the TX lane polarity must be inverted in the
- * PCS, via the DIGITAL_CONTROL_2 register.
- */
-int nxp_sja1105_sgmii_pma_config(struct dw_xpcs *xpcs)
-{
-	return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL2,
-			  DW_VR_MII_DIG_CTRL2_TX_POL_INV);
-}
-
 static int nxp_sja1110_pma_config(struct dw_xpcs *xpcs,
 				  u16 txpll_fbdiv, u16 txpll_refdiv,
 				  u16 rxpll_fbdiv, u16 rxpll_refdiv,
diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
index 3d1bd5aac093..670441186cc6 100644
--- a/drivers/net/pcs/pcs-xpcs.c
+++ b/drivers/net/pcs/pcs-xpcs.c
@@ -808,6 +808,26 @@ static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
 			   BMCR_SPEED1000);
 }
 
+static int xpcs_pma_config(struct dw_xpcs *xpcs, const struct dw_xpcs_compat *compat)
+{
+	int ret;
+
+	if (xpcs->need_opposite_tx_polarity) {
+		ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL2,
+				 DW_VR_MII_DIG_CTRL2_TX_POL_INV);
+		if (ret)
+			return ret;
+	}
+
+	if (compat->pma_config) {
+		ret = compat->pma_config(xpcs);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
 			  const unsigned long *advertising,
 			  unsigned int neg_mode)
@@ -859,13 +879,7 @@ static int xpcs_do_config(struct dw_xpcs *xpcs, phy_interface_t interface,
 		return -EINVAL;
 	}
 
-	if (compat->pma_config) {
-		ret = compat->pma_config(xpcs);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return xpcs_pma_config(xpcs, compat);
 }
 
 static int xpcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
@@ -1341,7 +1355,6 @@ static const struct dw_xpcs_compat nxp_sja1105_xpcs_compat[] = {
 		.interface = PHY_INTERFACE_MODE_SGMII,
 		.supported = xpcs_sgmii_features,
 		.an_mode = DW_AN_C37_SGMII,
-		.pma_config = nxp_sja1105_sgmii_pma_config,
 	}, {
 	}
 };
@@ -1500,6 +1513,14 @@ static struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev)
 	else
 		xpcs->need_reset = true;
 
+	/* In NXP SJA1105, the PCS is integrated with a PMA that has the TX
+	 * lane polarity inverted by default (PLUS is MINUS, MINUS is PLUS).
+	 * To obtain normal non-inverted behavior, the TX lane polarity must be
+	 * inverted in the PCS, via the DIGITAL_CONTROL_2 register.
+	 */
+	if (xpcs->desc->compat == nxp_sja1105_xpcs_compat)
+		xpcs->need_opposite_tx_polarity = true;
+
 	return xpcs;
 
 out_clear_clks:
diff --git a/drivers/net/pcs/pcs-xpcs.h b/drivers/net/pcs/pcs-xpcs.h
index 929fa238445e..2a92e101da1b 100644
--- a/drivers/net/pcs/pcs-xpcs.h
+++ b/drivers/net/pcs/pcs-xpcs.h
@@ -113,6 +113,7 @@ struct dw_xpcs {
 	struct phylink_pcs pcs;
 	phy_interface_t interface;
 	bool need_reset;
+	bool need_opposite_tx_polarity;
 	u8 eee_mult_fact;
 };
 
@@ -121,7 +122,6 @@ int xpcs_write(struct dw_xpcs *xpcs, int dev, u32 reg, u16 val);
 int xpcs_modify(struct dw_xpcs *xpcs, int dev, u32 reg, u16 mask, u16 set);
 int xpcs_read_vpcs(struct dw_xpcs *xpcs, int reg);
 int xpcs_write_vpcs(struct dw_xpcs *xpcs, int reg, u16 val);
-int nxp_sja1105_sgmii_pma_config(struct dw_xpcs *xpcs);
 int nxp_sja1110_sgmii_pma_config(struct dw_xpcs *xpcs);
 int nxp_sja1110_2500basex_pma_config(struct dw_xpcs *xpcs);
 int txgbe_xpcs_switch_mode(struct dw_xpcs *xpcs, phy_interface_t interface);
-- 
2.34.1