[net-next PATCH v4 07/13] net: dsa: qca8k: add explicit SGMII PLL enable

[Ansuel Smith <ansuelsmth@gmail.com>]

Support enabling PLL on the SGMII CPU port. Some device require this
special configuration or no traffic is transmitted and the switch
doesn't work at all. A dedicated binding is added to the CPU node
port to apply the correct reg on mac config.
Fail to correctly configure sgmii with qca8327 switch and warn if pll is
used on qca8337 with a revision greater than 1.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 drivers/net/dsa/qca8k.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 126f20b0b94c..afdfbcbbdb52 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -1245,8 +1245,20 @@ qca8k_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
 		if (ret)
 			return;
 
-		val |= QCA8K_SGMII_EN_PLL | QCA8K_SGMII_EN_RX |
-			QCA8K_SGMII_EN_TX | QCA8K_SGMII_EN_SD;
+		val |= QCA8K_SGMII_EN_SD;
+
+		if (of_property_read_bool(dp->dn, "qca,sgmii-enable-pll")) {
+			if (priv->switch_id == QCA8K_ID_QCA8327) {
+				dev_err(priv->dev, "SGMII PLL should NOT be enabled for qca8327. Aborting enabling");
+				return;
+			}
+
+			if (priv->switch_revision < 2)
+				dev_warn(priv->dev, "SGMII PLL should NOT be enabled for qca8337 with revision 2 or more.");
+
+			val |= QCA8K_SGMII_EN_PLL | QCA8K_SGMII_EN_RX |
+			       QCA8K_SGMII_EN_TX;
+		}
 
 		if (dsa_is_cpu_port(ds, port)) {
 			/* CPU port, we're talking to the CPU MAC, be a PHY */
-- 
2.32.0