net: ethernet: mtk-star-emac: add clock pad selection for RMII

This patch add a new dts property named "mediatek,rmii-rxc" parsing
in driver, which will configure MAC to select which pin the RMII reference
clock is connected to, TXC or RXC.

TXC pad is the default reference clock pin. If user wants to use RXC pad
instead, add "mediatek,rmii-rxc" to corresponding device node.
Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Signed-off-by: Yinghua Pan <ot_yinghua.pan@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_star_emac.c

@@ -188,6 +188,8 @@ static const char *const mtk_star_clk_names[] = { "core", "reg", "trans" };
 #define MTK_PERICFG_REG_NIC_CFG_CON_V2		0x0c10
 #define MTK_PERICFG_REG_NIC_CFG_CON_CFG_INTF	GENMASK(3, 0)
 #define MTK_PERICFG_BIT_NIC_CFG_CON_RMII	1
+#define MTK_PERICFG_BIT_NIC_CFG_CON_CLK		BIT(0)
+#define MTK_PERICFG_BIT_NIC_CFG_CON_CLK_V2	BIT(8)
 
 /* Represents the actual structure of descriptors used by the MAC. We can
  * reuse the same structure for both TX and RX - the layout is the same, only
@@ -264,6 +266,7 @@ struct mtk_star_priv {
 	int speed;
 	int duplex;
 	int pause;
+	bool rmii_rxc;
 
 	const struct mtk_star_compat *compat_data;
 
@@ -1527,6 +1530,8 @@ static int mtk_star_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	priv->rmii_rxc = of_property_read_bool(of_node, "mediatek,rmii-rxc");
+
 	if (priv->compat_data->set_interface_mode) {
 		ret = priv->compat_data->set_interface_mode(ndev);
 		if (ret) {
@@ -1571,17 +1576,25 @@ static int mt8516_set_interface_mode(struct net_device *ndev)
 {
 	struct mtk_star_priv *priv = netdev_priv(ndev);
 	struct device *dev = mtk_star_get_dev(priv);
-	unsigned int intf_val;
+	unsigned int intf_val, ret, rmii_rxc;
 
 	switch (priv->phy_intf) {
 	case PHY_INTERFACE_MODE_RMII:
 		intf_val = MTK_PERICFG_BIT_NIC_CFG_CON_RMII;
+		rmii_rxc = priv->rmii_rxc ? 0 : MTK_PERICFG_BIT_NIC_CFG_CON_CLK;
 		break;
 	default:
 		dev_err(dev, "This interface not supported\n");
 		return -EINVAL;
 	}
 
+	ret = regmap_update_bits(priv->pericfg,
+				 MTK_PERICFG_REG_NIC_CFG1_CON,
+				 MTK_PERICFG_BIT_NIC_CFG_CON_CLK,
+				 rmii_rxc);
+	if (ret)
+		return ret;
+
 	return regmap_update_bits(priv->pericfg,
 				  MTK_PERICFG_REG_NIC_CFG0_CON,
 				  MTK_PERICFG_REG_NIC_CFG_CON_CFG_INTF,
@@ -1597,6 +1610,7 @@ static int mt8365_set_interface_mode(struct net_device *ndev)
 	switch (priv->phy_intf) {
 	case PHY_INTERFACE_MODE_RMII:
 		intf_val = MTK_PERICFG_BIT_NIC_CFG_CON_RMII;
+		intf_val |= priv->rmii_rxc ? 0 : MTK_PERICFG_BIT_NIC_CFG_CON_CLK_V2;
 		break;
 	default:
 		dev_err(dev, "This interface not supported\n");
@@ -1605,7 +1619,8 @@ static int mt8365_set_interface_mode(struct net_device *ndev)
 
 	return regmap_update_bits(priv->pericfg,
 				  MTK_PERICFG_REG_NIC_CFG_CON_V2,
-				  MTK_PERICFG_REG_NIC_CFG_CON_CFG_INTF,
+				  MTK_PERICFG_REG_NIC_CFG_CON_CFG_INTF |
+				  MTK_PERICFG_BIT_NIC_CFG_CON_CLK_V2,
 				  intf_val);
 }