Older Intel GSW150 chip doesn't have a SGMII/1000Base-X/2500Base-X PCS.
Prepare for supporting Intel GSW150 by skipping PCS reset and
initialization in case no .mac_select_pcs operation is defined.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
v2: new patch

 drivers/net/dsa/lantiq/mxl-gsw1xx.c | 37 ++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.c b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
index 718837bf1c1ef..d6258fe3afb8e 100644
--- a/drivers/net/dsa/lantiq/mxl-gsw1xx.c
+++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
@@ -578,6 +578,28 @@ static struct regmap *gsw1xx_regmap_init(struct gsw1xx_priv *priv,
 				priv, &config);
 }
 
+static int gsw1xx_serdes_pcs_init(struct gsw1xx_priv *priv)
+{
+	/* do nothing if the chip doesn't have a SerDes PCS */
+	if (!priv->gswip.hw_info->mac_select_pcs)
+		return 0;
+
+	priv->pcs.ops = &gsw1xx_pcs_ops;
+	priv->pcs.poll = true;
+	__set_bit(PHY_INTERFACE_MODE_SGMII,
+		  priv->pcs.supported_interfaces);
+	__set_bit(PHY_INTERFACE_MODE_1000BASEX,
+		  priv->pcs.supported_interfaces);
+	if (priv->gswip.hw_info->supports_2500m)
+		__set_bit(PHY_INTERFACE_MODE_2500BASEX,
+			  priv->pcs.supported_interfaces);
+	priv->tbi_interface = PHY_INTERFACE_MODE_NA;
+
+	/* assert SGMII reset to power down SGMII unit */
+	return regmap_set_bits(priv->shell, GSW1XX_SHELL_RST_REQ,
+			       GSW1XX_RST_REQ_SGMII_SHELL);
+}
+
 static int gsw1xx_probe(struct mdio_device *mdiodev)
 {
 	struct device *dev = &mdiodev->dev;
@@ -630,20 +652,7 @@ static int gsw1xx_probe(struct mdio_device *mdiodev)
 	if (IS_ERR(priv->shell))
 		return PTR_ERR(priv->shell);
 
-	priv->pcs.ops = &gsw1xx_pcs_ops;
-	priv->pcs.poll = true;
-	__set_bit(PHY_INTERFACE_MODE_SGMII,
-		  priv->pcs.supported_interfaces);
-	__set_bit(PHY_INTERFACE_MODE_1000BASEX,
-		  priv->pcs.supported_interfaces);
-	if (priv->gswip.hw_info->supports_2500m)
-		__set_bit(PHY_INTERFACE_MODE_2500BASEX,
-			  priv->pcs.supported_interfaces);
-	priv->tbi_interface = PHY_INTERFACE_MODE_NA;
-
-	/* assert SGMII reset to power down SGMII unit */
-	ret = regmap_set_bits(priv->shell, GSW1XX_SHELL_RST_REQ,
-			      GSW1XX_RST_REQ_SGMII_SHELL);
+	ret = gsw1xx_serdes_pcs_init(priv);
 	if (ret < 0)
 		return ret;
 
-- 
2.52.0